diff --git a/adb/Android.bp b/adb/Android.bp
index 226e3eb..3dc70b5 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -629,6 +629,7 @@
         "libselinux",
     ],
     test_suites: ["device-tests"],
+    require_root: true,
 }
 
 python_test_host {
diff --git a/adb/client/adb_install.cpp b/adb/client/adb_install.cpp
index a6e8998..042a2d6 100644
--- a/adb/client/adb_install.cpp
+++ b/adb/client/adb_install.cpp
@@ -201,69 +201,68 @@
 #else
         error_exit("fastdeploy is disabled");
 #endif
-    } else {
-        struct stat sb;
-        if (stat(file, &sb) == -1) {
-            fprintf(stderr, "adb: failed to stat %s: %s\n", file, strerror(errno));
-            return 1;
-        }
+    }
 
-        unique_fd local_fd(adb_open(file, O_RDONLY | O_CLOEXEC));
-        if (local_fd < 0) {
-            fprintf(stderr, "adb: failed to open %s: %s\n", file, strerror(errno));
-            return 1;
-        }
-
-#ifdef __linux__
-        posix_fadvise(local_fd.get(), 0, 0, POSIX_FADV_SEQUENTIAL | POSIX_FADV_NOREUSE);
-#endif
-
-        const bool use_abb = can_use_feature(kFeatureAbb);
-        std::string error;
-        std::vector<std::string> cmd_args = {use_abb ? "package" : "exec:cmd package"};
-        cmd_args.reserve(argc + 3);
-
-        // don't copy the APK name, but, copy the rest of the arguments as-is
-        while (argc-- > 1) {
-            if (use_abb) {
-                cmd_args.push_back(*argv++);
-            } else {
-                cmd_args.push_back(escape_arg(*argv++));
-            }
-        }
-
-        // add size parameter [required for streaming installs]
-        // do last to override any user specified value
-        cmd_args.push_back("-S");
-        cmd_args.push_back(
-                android::base::StringPrintf("%" PRIu64, static_cast<uint64_t>(sb.st_size)));
-
-        if (is_apex) {
-            cmd_args.push_back("--apex");
-        }
-
-        unique_fd remote_fd;
-        if (use_abb) {
-            remote_fd = send_abb_exec_command(cmd_args, &error);
-        } else {
-            remote_fd.reset(adb_connect(android::base::Join(cmd_args, " "), &error));
-        }
-        if (remote_fd < 0) {
-            fprintf(stderr, "adb: connect error for write: %s\n", error.c_str());
-            return 1;
-        }
-
-        copy_to_file(local_fd.get(), remote_fd.get());
-
-        char buf[BUFSIZ];
-        read_status_line(remote_fd.get(), buf, sizeof(buf));
-        if (!strncmp("Success", buf, 7)) {
-            fputs(buf, stdout);
-            return 0;
-        }
-        fprintf(stderr, "adb: failed to install %s: %s", file, buf);
+    struct stat sb;
+    if (stat(file, &sb) == -1) {
+        fprintf(stderr, "adb: failed to stat %s: %s\n", file, strerror(errno));
         return 1;
     }
+
+    unique_fd local_fd(adb_open(file, O_RDONLY | O_CLOEXEC));
+    if (local_fd < 0) {
+        fprintf(stderr, "adb: failed to open %s: %s\n", file, strerror(errno));
+        return 1;
+    }
+
+#ifdef __linux__
+    posix_fadvise(local_fd.get(), 0, 0, POSIX_FADV_SEQUENTIAL | POSIX_FADV_NOREUSE);
+#endif
+
+    const bool use_abb = can_use_feature(kFeatureAbbExec);
+    std::string error;
+    std::vector<std::string> cmd_args = {use_abb ? "package" : "exec:cmd package"};
+    cmd_args.reserve(argc + 3);
+
+    // don't copy the APK name, but, copy the rest of the arguments as-is
+    while (argc-- > 1) {
+        if (use_abb) {
+            cmd_args.push_back(*argv++);
+        } else {
+            cmd_args.push_back(escape_arg(*argv++));
+        }
+    }
+
+    // add size parameter [required for streaming installs]
+    // do last to override any user specified value
+    cmd_args.push_back("-S");
+    cmd_args.push_back(android::base::StringPrintf("%" PRIu64, static_cast<uint64_t>(sb.st_size)));
+
+    if (is_apex) {
+        cmd_args.push_back("--apex");
+    }
+
+    unique_fd remote_fd;
+    if (use_abb) {
+        remote_fd = send_abb_exec_command(cmd_args, &error);
+    } else {
+        remote_fd.reset(adb_connect(android::base::Join(cmd_args, " "), &error));
+    }
+    if (remote_fd < 0) {
+        fprintf(stderr, "adb: connect error for write: %s\n", error.c_str());
+        return 1;
+    }
+
+    copy_to_file(local_fd.get(), remote_fd.get());
+
+    char buf[BUFSIZ];
+    read_status_line(remote_fd.get(), buf, sizeof(buf));
+    if (!strncmp("Success", buf, 7)) {
+        fputs(buf, stdout);
+        return 0;
+    }
+    fprintf(stderr, "adb: failed to install %s: %s", file, buf);
+    return 1;
 }
 
 static int install_app_legacy(int argc, const char** argv, bool use_fastdeploy,
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index fe2bdfe..a0818d3 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -1713,8 +1713,12 @@
         }
 
         if (CanUseFeature(features, kFeatureRemountShell)) {
-            const char* arg[2] = {"shell", "remount"};
-            return adb_shell(2, arg);
+            std::vector<const char*> args = {"shell"};
+            args.insert(args.cend(), argv, argv + argc);
+            return adb_shell(args.size(), args.data());
+        } else if (argc > 1) {
+            auto command = android::base::StringPrintf("%s:%s", argv[0], argv[1]);
+            return adb_connect_command(command);
         } else {
             return adb_connect_command("remount:");
         }
diff --git a/adb/client/file_sync_client.cpp b/adb/client/file_sync_client.cpp
index 5d10238..703eb2f 100644
--- a/adb/client/file_sync_client.cpp
+++ b/adb/client/file_sync_client.cpp
@@ -849,6 +849,16 @@
     return true;
 }
 
+// dirname("//foo") returns "//", so we can't do the obvious `path == "/"`.
+static bool is_root_dir(std::string_view path) {
+    for (char c : path) {
+        if (c != '/') {
+            return false;
+        }
+    }
+    return true;
+}
+
 static bool copy_local_dir_remote(SyncConnection& sc, std::string lpath,
                                   std::string rpath, bool check_timestamps,
                                   bool list_only) {
@@ -862,8 +872,8 @@
     std::vector<copyinfo> file_list;
     std::vector<std::string> directory_list;
 
-    for (std::string dirpath = rpath; dirpath != "/"; dirpath = android::base::Dirname(dirpath)) {
-        directory_list.push_back(dirpath);
+    for (std::string path = rpath; !is_root_dir(path); path = android::base::Dirname(path)) {
+        directory_list.push_back(path);
     }
     std::reverse(directory_list.begin(), directory_list.end());
 
diff --git a/adb/client/usb_linux.cpp b/adb/client/usb_linux.cpp
index 17b4db1..24e722e 100644
--- a/adb/client/usb_linux.cpp
+++ b/adb/client/usb_linux.cpp
@@ -406,25 +406,44 @@
     }
 }
 
-int usb_write(usb_handle *h, const void *_data, int len)
-{
+static int usb_write_split(usb_handle* h, unsigned char* data, int len) {
+    for (int i = 0; i < len; i += 16384) {
+        int chunk_size = (i + 16384 > len) ? len - i : 16384;
+        int n = usb_bulk_write(h, data + i, chunk_size);
+        if (n != chunk_size) {
+            D("ERROR: n = %d, errno = %d (%s)", n, errno, strerror(errno));
+            return -1;
+        }
+    }
+
+    return len;
+}
+
+int usb_write(usb_handle* h, const void* _data, int len) {
     D("++ usb_write ++");
 
-    unsigned char *data = (unsigned char*) _data;
+    unsigned char* data = (unsigned char*)_data;
+
+    // The kernel will attempt to allocate a contiguous buffer for each write we submit.
+    // This might fail due to heap fragmentation, so attempt a contiguous write once, and if that
+    // fails, retry after having split the data into 16kB chunks to avoid allocation failure.
     int n = usb_bulk_write(h, data, len);
-    if (n != len) {
-        D("ERROR: n = %d, errno = %d (%s)", n, errno, strerror(errno));
+    if (n == -1 && errno == ENOMEM) {
+        n = usb_write_split(h, data, len);
+    }
+
+    if (n == -1) {
         return -1;
     }
 
     if (h->zero_mask && !(len & h->zero_mask)) {
         // If we need 0-markers and our transfer is an even multiple of the packet size,
         // then send a zero marker.
-        return usb_bulk_write(h, _data, 0) == 0 ? n : -1;
+        return usb_bulk_write(h, _data, 0) == 0 ? len : -1;
     }
 
     D("-- usb_write --");
-    return n;
+    return len;
 }
 
 int usb_read(usb_handle *h, void *_data, int len)
diff --git a/adb/test_device.py b/adb/test_device.py
index dbd80ed..32d797e 100755
--- a/adb/test_device.py
+++ b/adb/test_device.py
@@ -903,6 +903,18 @@
             remote_path += '/filename'
             self.device.push(local=tmp_file.name, remote=remote_path)
 
+    def test_push_multiple_slash_root(self):
+        """Regression test for pushing to //data/local/tmp.
+
+        Bug: http://b/141311284
+        """
+        with tempfile.NamedTemporaryFile() as tmp_file:
+            tmp_file.write('\0' * 1024 * 1024)
+            tmp_file.flush()
+            remote_path = '/' + self.DEVICE_TEMP_DIR + '/test_push_multiple_slash_root'
+            self.device.shell(['rm', '-rf', remote_path])
+            self.device.push(local=tmp_file.name, remote=remote_path)
+
     def _test_pull(self, remote_file, checksum):
         tmp_write = tempfile.NamedTemporaryFile(mode='wb', delete=False)
         tmp_write.close()
diff --git a/adb/transport.h b/adb/transport.h
index 61a3d9a..c38cb1d 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -65,8 +65,10 @@
 extern const char* const kFeatureApex;
 // adbd has b/110953234 fixed.
 extern const char* const kFeatureFixedPushMkdir;
-// adbd supports android binder bridge (abb).
+// adbd supports android binder bridge (abb) in interactive mode using shell protocol.
 extern const char* const kFeatureAbb;
+// adbd supports abb using raw pipe.
+extern const char* const kFeatureAbbExec;
 // adbd properly updates symlink timestamps on push.
 extern const char* const kFeatureFixedPushSymlinkTimestamp;
 extern const char* const kFeatureRemountShell;
diff --git a/base/include/android-base/endian.h b/base/include/android-base/endian.h
index 2d0f614..8fa6365 100644
--- a/base/include/android-base/endian.h
+++ b/base/include/android-base/endian.h
@@ -51,8 +51,10 @@
 /* macOS has some of the basics. */
 #include <sys/_endian.h>
 #else
-/* Windows has even less. */
+/* Windows has some of the basics as well. */
 #include <sys/param.h>
+#include <winsock2.h>
+/* winsock2.h *must* be included before the following four macros. */
 #define htons(x) __builtin_bswap16(x)
 #define htonl(x) __builtin_bswap32(x)
 #define ntohs(x) __builtin_bswap16(x)
diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index dd24aac..d08a59f 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -311,6 +311,7 @@
     {"shutdown,userrequested,recovery", 182},
     {"reboot,unknown[0-9]*", 183},
     {"reboot,longkey,.*", 184},
+    {"reboot,boringssl-self-check-failed", 185},
 };
 
 // Converts a string value representing the reason the system booted to an
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index fbc8b97..c9a193c 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -176,7 +176,7 @@
   if (crasher_pid != -1) {
     kill(crasher_pid, SIGKILL);
     int status;
-    waitpid(crasher_pid, &status, WUNTRACED);
+    TEMP_FAILURE_RETRY(waitpid(crasher_pid, &status, WUNTRACED));
   }
 
   android::base::SetProperty(kWaitForGdbKey, previous_wait_for_gdb ? "1" : "0");
@@ -195,8 +195,7 @@
 void CrasherTest::FinishIntercept(int* result) {
   InterceptResponse response;
 
-  // Timeout for tombstoned intercept is 10 seconds.
-  ssize_t rc = TIMEOUT(20, read(intercept_fd.get(), &response, sizeof(response)));
+  ssize_t rc = TIMEOUT(30, read(intercept_fd.get(), &response, sizeof(response)));
   if (rc == -1) {
     FAIL() << "failed to read response from tombstoned: " << strerror(errno);
   } else if (rc == 0) {
@@ -233,7 +232,7 @@
     FAIL() << "crasher pipe uninitialized";
   }
 
-  ssize_t rc = write(crasher_pipe.get(), "\n", 1);
+  ssize_t rc = TEMP_FAILURE_RETRY(write(crasher_pipe.get(), "\n", 1));
   if (rc == -1) {
     FAIL() << "failed to write to crasher pipe: " << strerror(errno);
   } else if (rc == 0) {
@@ -243,7 +242,7 @@
 
 void CrasherTest::AssertDeath(int signo) {
   int status;
-  pid_t pid = TIMEOUT(10, waitpid(crasher_pid, &status, 0));
+  pid_t pid = TIMEOUT(30, waitpid(crasher_pid, &status, 0));
   if (pid != crasher_pid) {
     printf("failed to wait for crasher (expected pid %d, return value %d): %s\n", crasher_pid, pid,
            strerror(errno));
@@ -441,7 +440,7 @@
   FinishCrasher();
 
   int status;
-  ASSERT_EQ(crasher_pid, waitpid(crasher_pid, &status, WUNTRACED));
+  ASSERT_EQ(crasher_pid, TEMP_FAILURE_RETRY(waitpid(crasher_pid, &status, WUNTRACED)));
   ASSERT_TRUE(WIFSTOPPED(status));
   ASSERT_EQ(SIGSTOP, WSTOPSIG(status));
 
@@ -603,13 +602,15 @@
   policy += "\nclone: 1";
   policy += "\nsigaltstack: 1";
   policy += "\nnanosleep: 1";
+  policy += "\ngetrlimit: 1";
+  policy += "\nugetrlimit: 1";
 
   FILE* tmp_file = tmpfile();
   if (!tmp_file) {
     PLOG(FATAL) << "tmpfile failed";
   }
 
-  unique_fd tmp_fd(dup(fileno(tmp_file)));
+  unique_fd tmp_fd(TEMP_FAILURE_RETRY(dup(fileno(tmp_file))));
   if (!android::base::WriteStringToFd(policy, tmp_fd.get())) {
     PLOG(FATAL) << "failed to write policy to tmpfile";
   }
@@ -822,7 +823,7 @@
   FinishCrasher();
 
   int status;
-  ASSERT_EQ(crasher_pid, waitpid(crasher_pid, &status, 0));
+  ASSERT_EQ(crasher_pid, TEMP_FAILURE_RETRY(waitpid(crasher_pid, &status, 0)));
   ASSERT_TRUE(WIFSTOPPED(status));
   ASSERT_EQ(SIGABRT, WSTOPSIG(status));
 
@@ -837,7 +838,7 @@
   regex += R"( \(.+debuggerd_test)";
   ASSERT_MATCH(result, regex.c_str());
 
-  ASSERT_EQ(crasher_pid, waitpid(crasher_pid, &status, 0));
+  ASSERT_EQ(crasher_pid, TEMP_FAILURE_RETRY(waitpid(crasher_pid, &status, 0)));
   ASSERT_TRUE(WIFSTOPPED(status));
   ASSERT_EQ(SIGABRT, WSTOPSIG(status));
 
@@ -851,7 +852,7 @@
 
   StartProcess([]() {
     android_fdsan_set_error_level(ANDROID_FDSAN_ERROR_LEVEL_WARN_ONCE);
-    unique_fd fd(open("/dev/null", O_RDONLY | O_CLOEXEC));
+    unique_fd fd(TEMP_FAILURE_RETRY(open("/dev/null", O_RDONLY | O_CLOEXEC)));
     if (fd == -1) {
       abort();
     }
@@ -886,13 +887,13 @@
     raise(DEBUGGER_SIGNAL);
 
     errno = 0;
-    rc = waitpid(-1, &status, __WALL | __WNOTHREAD);
+    rc = TEMP_FAILURE_RETRY(waitpid(-1, &status, __WALL | __WNOTHREAD));
     if (rc != -1 || errno != ECHILD) {
       errx(2, "second waitpid returned %d (%s), expected failure with ECHILD", rc, strerror(errno));
     }
     _exit(0);
   } else {
-    rc = waitpid(forkpid, &status, 0);
+    rc = TEMP_FAILURE_RETRY(waitpid(forkpid, &status, 0));
     ASSERT_EQ(forkpid, rc);
     ASSERT_TRUE(WIFEXITED(status));
     ASSERT_EQ(0, WEXITSTATUS(status));
diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 546bce2..f452a64 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -189,7 +189,11 @@
     // will violate ODR.
     shared_libs: [],
 
-    header_libs: ["bootimg_headers"],
+    header_libs: [
+        "avb_headers",
+        "bootimg_headers",
+    ],
+
     static_libs: [
         "libziparchive",
         "libsparse",
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 4737ae4..2fe3b1a 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -51,6 +51,7 @@
 #include <utility>
 #include <vector>
 
+#include <android-base/endian.h>
 #include <android-base/file.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
@@ -59,6 +60,7 @@
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
 #include <build/version.h>
+#include <libavb/libavb.h>
 #include <liblp/liblp.h>
 #include <platform_tools_version.h>
 #include <sparse/sparse.h>
@@ -874,7 +876,7 @@
         return false;
     }
 
-    if (sparse_file* s = sparse_file_import_auto(fd, false, false)) {
+    if (sparse_file* s = sparse_file_import(fd, false, false)) {
         buf->image_size = sparse_file_len(s, false, false);
         sparse_file_destroy(s);
     } else {
@@ -919,33 +921,50 @@
     return load_buf_fd(fd.release(), buf);
 }
 
-static void rewrite_vbmeta_buffer(struct fastboot_buffer* buf) {
+static void rewrite_vbmeta_buffer(struct fastboot_buffer* buf, bool vbmeta_in_boot) {
     // Buffer needs to be at least the size of the VBMeta struct which
     // is 256 bytes.
     if (buf->sz < 256) {
         return;
     }
 
-    int fd = make_temporary_fd("vbmeta rewriting");
-
     std::string data;
     if (!android::base::ReadFdToString(buf->fd, &data)) {
         die("Failed reading from vbmeta");
     }
 
+    uint64_t vbmeta_offset = 0;
+    if (vbmeta_in_boot) {
+        // Tries to locate top-level vbmeta from boot.img footer.
+        uint64_t footer_offset = buf->sz - AVB_FOOTER_SIZE;
+        if (0 != data.compare(footer_offset, AVB_FOOTER_MAGIC_LEN, AVB_FOOTER_MAGIC)) {
+            die("Failed to find AVB_FOOTER at offset: %" PRId64, footer_offset);
+        }
+        const AvbFooter* footer = reinterpret_cast<const AvbFooter*>(data.c_str() + footer_offset);
+        vbmeta_offset = be64toh(footer->vbmeta_offset);
+    }
+    // Ensures there is AVB_MAGIC at vbmeta_offset.
+    if (0 != data.compare(vbmeta_offset, AVB_MAGIC_LEN, AVB_MAGIC)) {
+        die("Failed to find AVB_MAGIC at offset: %" PRId64, vbmeta_offset);
+    }
+
+    fprintf(stderr, "Rewriting vbmeta struct at offset: %" PRId64 "\n", vbmeta_offset);
+
     // There's a 32-bit big endian |flags| field at offset 120 where
     // bit 0 corresponds to disable-verity and bit 1 corresponds to
     // disable-verification.
     //
     // See external/avb/libavb/avb_vbmeta_image.h for the layout of
     // the VBMeta struct.
+    uint64_t flags_offset = 123 + vbmeta_offset;
     if (g_disable_verity) {
-        data[123] |= 0x01;
+        data[flags_offset] |= 0x01;
     }
     if (g_disable_verification) {
-        data[123] |= 0x02;
+        data[flags_offset] |= 0x02;
     }
 
+    int fd = make_temporary_fd("vbmeta rewriting");
     if (!android::base::WriteStringToFd(data, fd)) {
         die("Failed writing to modified vbmeta");
     }
@@ -954,14 +973,25 @@
     lseek(fd, 0, SEEK_SET);
 }
 
+static bool has_vbmeta_partition() {
+    std::string partition_type;
+    return fb->GetVar("partition-type:vbmeta", &partition_type) == fastboot::SUCCESS ||
+           fb->GetVar("partition-type:vbmeta_a", &partition_type) == fastboot::SUCCESS ||
+           fb->GetVar("partition-type:vbmeta_b", &partition_type) == fastboot::SUCCESS;
+}
+
 static void flash_buf(const std::string& partition, struct fastboot_buffer *buf)
 {
     sparse_file** s;
 
     // Rewrite vbmeta if that's what we're flashing and modification has been requested.
-    if ((g_disable_verity || g_disable_verification) &&
-        (partition == "vbmeta" || partition == "vbmeta_a" || partition == "vbmeta_b")) {
-        rewrite_vbmeta_buffer(buf);
+    if (g_disable_verity || g_disable_verification) {
+        if (partition == "vbmeta" || partition == "vbmeta_a" || partition == "vbmeta_b") {
+            rewrite_vbmeta_buffer(buf, false /* vbmeta_in_boot */);
+        } else if (!has_vbmeta_partition() &&
+                   (partition == "boot" || partition == "boot_a" || partition == "boot_b")) {
+            rewrite_vbmeta_buffer(buf, true /* vbmeta_in_boot */ );
+        }
     }
 
     switch (buf->type) {
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 4dbacd7..e50f7c3 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -36,6 +36,7 @@
 
 #include "fs_mgr_priv.h"
 
+using android::base::EndsWith;
 using android::base::ParseByteCount;
 using android::base::ParseInt;
 using android::base::ReadFileToString;
@@ -598,7 +599,7 @@
     return boot_devices;
 }
 
-FstabEntry BuildGsiUserdataFstabEntry() {
+FstabEntry BuildDsuUserdataFstabEntry() {
     constexpr uint32_t kFlags = MS_NOATIME | MS_NOSUID | MS_NODEV;
 
     FstabEntry userdata = {
@@ -627,7 +628,12 @@
     return false;
 }
 
-void TransformFstabForGsi(Fstab* fstab) {
+}  // namespace
+
+void TransformFstabForDsu(Fstab* fstab, const std::vector<std::string>& dsu_partitions) {
+    static constexpr char kGsiKeys[] =
+            "/avb/q-gsi.avbpubkey:/avb/r-gsi.avbpubkey:/avb/s-gsi.avbpubkey";
+    // Convert userdata
     // Inherit fstab properties for userdata.
     FstabEntry userdata;
     if (FstabEntry* entry = GetEntryForMountPoint(fstab, "/data")) {
@@ -639,19 +645,75 @@
             userdata.key_dir += "/gsi";
         }
     } else {
-        userdata = BuildGsiUserdataFstabEntry();
-    }
-
-    if (EraseFstabEntry(fstab, "/system")) {
-        fstab->emplace_back(BuildGsiSystemFstabEntry());
+        userdata = BuildDsuUserdataFstabEntry();
     }
 
     if (EraseFstabEntry(fstab, "/data")) {
         fstab->emplace_back(userdata);
     }
-}
 
-}  // namespace
+    // Convert others
+    for (auto&& partition : dsu_partitions) {
+        if (!EndsWith(partition, gsi::kDsuPostfix)) {
+            continue;
+        }
+        // userdata has been handled
+        if (StartsWith(partition, "user")) {
+            continue;
+        }
+        // dsu_partition_name = corresponding_partition_name + kDsuPostfix
+        // e.g.
+        //    system_gsi for system
+        //    product_gsi for product
+        //    vendor_gsi for vendor
+        std::string lp_name = partition.substr(0, partition.length() - strlen(gsi::kDsuPostfix));
+        std::string mount_point = "/" + lp_name;
+        std::vector<FstabEntry*> entries = GetEntriesForMountPoint(fstab, mount_point);
+        if (entries.empty()) {
+            FstabEntry entry = {
+                    .blk_device = partition,
+                    .mount_point = mount_point,
+                    .fs_type = "ext4",
+                    .flags = MS_RDONLY,
+                    .fs_options = "barrier=1",
+                    .avb_keys = kGsiKeys,
+                    // .logical_partition_name is required to look up AVB Hashtree descriptors.
+                    .logical_partition_name = "system"};
+            entry.fs_mgr_flags.wait = true;
+            entry.fs_mgr_flags.logical = true;
+            entry.fs_mgr_flags.first_stage_mount = true;
+            // Use the system key which may be in the vbmeta or vbmeta_system
+            // TODO: b/141284191
+            entry.vbmeta_partition = "vbmeta";
+            fstab->emplace_back(entry);
+            entry.vbmeta_partition = "vbmeta_system";
+            fstab->emplace_back(entry);
+        } else {
+            // If the corresponding partition exists, transform all its Fstab
+            // by pointing .blk_device to the DSU partition.
+            for (auto&& entry : entries) {
+                entry->blk_device = partition;
+                if (entry->avb_keys.size() > 0) {
+                    entry->avb_keys += ":";
+                }
+                // If the DSU is signed by OEM, the original Fstab already has the information
+                // required by avb, otherwise the DSU is GSI and will need the avb_keys as listed
+                // below.
+                entry->avb_keys += kGsiKeys;
+            }
+            // Make sure the ext4 is included to support GSI.
+            auto partition_ext4 =
+                    std::find_if(fstab->begin(), fstab->end(), [&](const auto& entry) {
+                        return entry.mount_point == mount_point && entry.fs_type == "ext4";
+                    });
+            if (partition_ext4 == fstab->end()) {
+                auto new_entry = *GetEntryForMountPoint(fstab, mount_point);
+                new_entry.fs_type = "ext4";
+                fstab->emplace_back(new_entry);
+            }
+        }
+    }
+}
 
 bool ReadFstabFromFile(const std::string& path, Fstab* fstab) {
     auto fstab_file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
@@ -667,7 +729,9 @@
         return false;
     }
     if (!is_proc_mounts && !access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
-        TransformFstabForGsi(fstab);
+        std::string lp_names;
+        ReadFileToString(gsi::kGsiLpNamesFile, &lp_names);
+        TransformFstabForDsu(fstab, Split(lp_names, ","));
     }
 
     SkipMountingPartitions(fstab);
@@ -779,6 +843,21 @@
     return nullptr;
 }
 
+std::vector<FstabEntry*> GetEntriesForMountPoint(Fstab* fstab, const std::string& path) {
+    std::vector<FstabEntry*> entries;
+    if (fstab == nullptr) {
+        return entries;
+    }
+
+    for (auto& entry : *fstab) {
+        if (entry.mount_point == path) {
+            entries.emplace_back(&entry);
+        }
+    }
+
+    return entries;
+}
+
 std::set<std::string> GetBootDevices() {
     // First check the kernel commandline, then try the device tree otherwise
     std::string dt_file_name = get_android_dt_dir() + "/boot_devices";
@@ -798,23 +877,6 @@
     return ExtraBootDevices(fstab);
 }
 
-FstabEntry BuildGsiSystemFstabEntry() {
-    // .logical_partition_name is required to look up AVB Hashtree descriptors.
-    FstabEntry system = {
-            .blk_device = "system_gsi",
-            .mount_point = "/system",
-            .fs_type = "ext4",
-            .flags = MS_RDONLY,
-            .fs_options = "barrier=1",
-            // could add more keys separated by ':'.
-            .avb_keys = "/avb/q-gsi.avbpubkey:/avb/r-gsi.avbpubkey:/avb/s-gsi.avbpubkey",
-            .logical_partition_name = "system"};
-    system.fs_mgr_flags.wait = true;
-    system.fs_mgr_flags.logical = true;
-    system.fs_mgr_flags.first_stage_mount = true;
-    return system;
-}
-
 std::string GetVerityDeviceName(const FstabEntry& entry) {
     std::string base_device;
     if (entry.mount_point == "/") {
diff --git a/fs_mgr/include_fstab/fstab/fstab.h b/fs_mgr/include_fstab/fstab/fstab.h
index c7193ab..d999ae1 100644
--- a/fs_mgr/include_fstab/fstab/fstab.h
+++ b/fs_mgr/include_fstab/fstab/fstab.h
@@ -101,9 +101,18 @@
 bool SkipMountingPartitions(Fstab* fstab);
 
 FstabEntry* GetEntryForMountPoint(Fstab* fstab, const std::string& path);
+// The Fstab can contain multiple entries for the same mount point with different configurations.
+std::vector<FstabEntry*> GetEntriesForMountPoint(Fstab* fstab, const std::string& path);
 
-// Helper method to build a GSI fstab entry for mounting /system.
-FstabEntry BuildGsiSystemFstabEntry();
+// This method builds DSU fstab entries and transfer the fstab.
+//
+// fstab points to the unmodified fstab.
+//
+// dsu_partitions contains partition names, e.g.
+//     dsu_partitions[0] = "system_gsi"
+//     dsu_partitions[1] = "userdata_gsi"
+//     dsu_partitions[2] = ...
+void TransformFstabForDsu(Fstab* fstab, const std::vector<std::string>& dsu_partitions);
 
 std::set<std::string> GetBootDevices();
 
diff --git a/fs_mgr/libdm/Android.bp b/fs_mgr/libdm/Android.bp
index 4cdea71..449a170 100644
--- a/fs_mgr/libdm/Android.bp
+++ b/fs_mgr/libdm/Android.bp
@@ -44,9 +44,24 @@
     },
 }
 
-cc_test {
-    name: "libdm_test",
-    defaults: ["fs_mgr_defaults"],
+filegroup {
+    name: "libdm_test_srcs",
+    srcs: [
+        "dm_test.cpp",
+        "loop_control_test.cpp",
+        "test_util.cpp",
+    ],
+}
+
+cc_defaults {
+    name: "libdm_defaults",
+    sanitize: {
+        misc_undefined: ["integer"],
+    },
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     static_libs: [
         "libdm",
         "libbase",
@@ -54,9 +69,10 @@
         "libfs_mgr",
         "liblog",
     ],
-    srcs: [
-        "dm_test.cpp",
-        "loop_control_test.cpp",
-        "test_util.cpp",
-    ]
+    srcs: [":libdm_test_srcs"],
+}
+
+cc_test {
+    name: "libdm_test",
+    defaults: ["libdm_defaults"],
 }
diff --git a/fs_mgr/libdm/vts_core/Android.bp b/fs_mgr/libdm/vts_core/Android.bp
new file mode 100644
index 0000000..2eceb28
--- /dev/null
+++ b/fs_mgr/libdm/vts_core/Android.bp
@@ -0,0 +1,23 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+cc_test {
+    name: "vts_libdm_test",
+    defaults: ["libdm_defaults"],
+    test_suites: ["vts-core"],
+    require_root: true,
+    test_min_api_level: 29,
+}
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
index 13aaf00..178b343 100644
--- a/fs_mgr/liblp/Android.bp
+++ b/fs_mgr/liblp/Android.bp
@@ -56,9 +56,26 @@
     export_include_dirs: ["include"],
 }
 
+filegroup {
+    name: "liblp_test_srcs",
+    srcs: [
+        "builder_test.cpp",
+        "device_test.cpp",
+        "io_test.cpp",
+        "test_partition_opener.cpp",
+        "utility_test.cpp",
+    ],
+}
+
 cc_defaults {
     name: "liblp_test_defaults",
-    defaults: ["fs_mgr_defaults"],
+    sanitize: {
+        misc_undefined: ["integer"],
+    },
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     cppflags: [
         "-Wno-unused-parameter",
     ],
@@ -73,23 +90,14 @@
         "libstorage_literals_headers",
     ],
     stl: "libc++_static",
-    srcs: [
-        "builder_test.cpp",
-        "device_test.cpp",
-        "io_test.cpp",
-        "test_partition_opener.cpp",
-        "utility_test.cpp",
-    ],
+    srcs: [":liblp_test_srcs"],
 }
 
 cc_test {
     name: "liblp_test",
     defaults: ["liblp_test_defaults"],
     test_config: "liblp_test.xml",
-    test_suites: [
-        "device-tests",
-        "vts-core",
-    ],
+    test_suites: ["device-tests"],
 }
 
 cc_test {
diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index 96068b1..7405039 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -1136,7 +1136,7 @@
     return true;
 }
 
-std::vector<Partition*> MetadataBuilder::ListPartitionsInGroup(const std::string& group_name) {
+std::vector<Partition*> MetadataBuilder::ListPartitionsInGroup(std::string_view group_name) {
     std::vector<Partition*> partitions;
     for (const auto& partition : partitions_) {
         if (partition->group_name() == group_name) {
diff --git a/fs_mgr/liblp/include/liblp/builder.h b/fs_mgr/liblp/include/liblp/builder.h
index 4d7f81d..b43ccf0 100644
--- a/fs_mgr/liblp/include/liblp/builder.h
+++ b/fs_mgr/liblp/include/liblp/builder.h
@@ -289,7 +289,7 @@
                          const std::vector<Interval>& free_region_hint = {});
 
     // Return the list of partitions belonging to a group.
-    std::vector<Partition*> ListPartitionsInGroup(const std::string& group_name);
+    std::vector<Partition*> ListPartitionsInGroup(std::string_view group_name);
 
     // Changes a partition's group. Size constraints will not be checked until
     // the metadata is exported, to avoid errors during potential group and
diff --git a/fs_mgr/liblp/vts_core/Android.bp b/fs_mgr/liblp/vts_core/Android.bp
new file mode 100644
index 0000000..7af0b9e
--- /dev/null
+++ b/fs_mgr/liblp/vts_core/Android.bp
@@ -0,0 +1,22 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+cc_test {
+    name: "vts_core_liblp_test",
+    defaults: ["liblp_test_defaults"],
+    test_suites: ["vts-core"],
+    test_min_api_level: 29,
+}
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 181aafb..834bf3b 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -32,6 +32,7 @@
         "libfs_mgr",
         "libfstab",
         "liblp",
+        "update_metadata-protos",
     ],
     whole_static_libs: [
         "libext2_uuid",
@@ -41,6 +42,9 @@
     header_libs: [
         "libfiemap_headers",
     ],
+    export_static_lib_headers: [
+        "update_metadata-protos",
+    ],
     export_header_lib_headers: [
         "libfiemap_headers",
     ],
@@ -51,6 +55,7 @@
     name: "libsnapshot_sources",
     srcs: [
         "snapshot.cpp",
+        "snapshot_metadata_updater.cpp",
         "partition_cow_creator.cpp",
         "utility.cpp",
     ],
@@ -87,10 +92,12 @@
     srcs: [
         "snapshot_test.cpp",
         "partition_cow_creator_test.cpp",
+        "snapshot_metadata_updater_test.cpp",
         "test_helpers.cpp",
     ],
     shared_libs: [
         "libbinder",
+        "libprotobuf-cpp-lite",
         "libutils",
     ],
     static_libs: [
@@ -107,3 +114,29 @@
         "libstorage_literals_headers",
     ],
 }
+
+cc_binary {
+    name: "snapshotctl",
+    srcs: [
+        "snapshotctl.cpp",
+    ],
+    static_libs: [
+        "libdm",
+        "libext2_uuid",
+        "libfiemap_binder",
+        "libfstab",
+        "libsnapshot",
+    ],
+    shared_libs: [
+        "libbase",
+        "libbinder",
+        "libext4_utils",
+        "libfs_mgr",
+        "libutils",
+        "liblog",
+        "liblp",
+    ],
+    init_rc: [
+        "snapshotctl.rc",
+    ],
+}
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 6bc09a1..0dd275a 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -19,6 +19,7 @@
 #include <chrono>
 #include <map>
 #include <memory>
+#include <ostream>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -29,6 +30,7 @@
 #include <libfiemap/image_manager.h>
 #include <liblp/builder.h>
 #include <liblp/liblp.h>
+#include <update_engine/update_metadata.pb.h>
 
 #ifndef FRIEND_TEST
 #define FRIEND_TEST(test_set_name, individual_test) \
@@ -83,12 +85,14 @@
     // operation via fastboot. This state can only be returned by WaitForMerge.
     Cancelled
 };
+std::ostream& operator<<(std::ostream& os, UpdateState state);
 
 class SnapshotManager final {
     using CreateLogicalPartitionParams = android::fs_mgr::CreateLogicalPartitionParams;
     using IPartitionOpener = android::fs_mgr::IPartitionOpener;
     using LpMetadata = android::fs_mgr::LpMetadata;
     using MetadataBuilder = android::fs_mgr::MetadataBuilder;
+    using DeltaArchiveManifest = chromeos_update_engine::DeltaArchiveManifest;
 
   public:
     // Dependency injection for testing.
@@ -98,6 +102,7 @@
         virtual std::string GetGsidDir() const = 0;
         virtual std::string GetMetadataDir() const = 0;
         virtual std::string GetSlotSuffix() const = 0;
+        virtual std::string GetOtherSlotSuffix() const = 0;
         virtual std::string GetSuperDevice(uint32_t slot) const = 0;
         virtual const IPartitionOpener& GetPartitionOpener() const = 0;
         virtual bool IsOverlayfsSetup() const = 0;
@@ -122,8 +127,9 @@
     // will fail if GetUpdateState() != None.
     bool BeginUpdate();
 
-    // Cancel an update; any snapshots will be deleted. This will fail if the
-    // state != Initiated or None.
+    // Cancel an update; any snapshots will be deleted. This is allowed if the
+    // state == Initiated, None, or Unverified (before rebooting to the new
+    // slot).
     bool CancelUpdate();
 
     // Mark snapshot writes as having completed. After this, new snapshots cannot
@@ -169,9 +175,7 @@
     // Create necessary COW device / files for OTA clients. New logical partitions will be added to
     // group "cow" in target_metadata. Regions of partitions of current_metadata will be
     // "write-protected" and snapshotted.
-    bool CreateUpdateSnapshots(MetadataBuilder* target_metadata, const std::string& target_suffix,
-                               MetadataBuilder* current_metadata, const std::string& current_suffix,
-                               const std::map<std::string, uint64_t>& cow_sizes);
+    bool CreateUpdateSnapshots(const DeltaArchiveManifest& manifest);
 
     // Map a snapshotted partition for OTA clients to write to. Write-protected regions are
     // determined previously in CreateSnapshots.
@@ -188,6 +192,9 @@
     // call to CreateLogicalPartitions when snapshots are present.
     bool CreateLogicalAndSnapshotPartitions(const std::string& super_device);
 
+    // Dump debug information.
+    bool Dump(std::ostream& os);
+
   private:
     FRIEND_TEST(SnapshotTest, CleanFirstStageMount);
     FRIEND_TEST(SnapshotTest, CreateSnapshot);
@@ -392,6 +399,13 @@
     // The reverse of MapPartitionWithSnapshot.
     bool UnmapPartitionWithSnapshot(LockedFile* lock, const std::string& target_partition_name);
 
+    // If there isn't a previous update, return true. |needs_merge| is set to false.
+    // If there is a previous update but the device has not boot into it, tries to cancel the
+    //   update and delete any snapshots. Return true if successful. |needs_merge| is set to false.
+    // If there is a previous update and the device has boot into it, do nothing and return true.
+    //   |needs_merge| is set to true.
+    bool TryCancelUpdate(bool* needs_merge);
+
     std::string gsid_dir_;
     std::string metadata_dir_;
     std::unique_ptr<IDeviceInfo> device_;
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.cpp b/fs_mgr/libsnapshot/partition_cow_creator.cpp
index 3163e61..4250d23 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.cpp
+++ b/fs_mgr/libsnapshot/partition_cow_creator.cpp
@@ -25,6 +25,9 @@
 using android::fs_mgr::Interval;
 using android::fs_mgr::kDefaultBlockSize;
 using android::fs_mgr::Partition;
+using chromeos_update_engine::InstallOperation;
+template <typename T>
+using RepeatedPtrField = google::protobuf::RepeatedPtrField<T>;
 
 namespace android {
 namespace snapshot {
@@ -117,9 +120,15 @@
     return snapshot_size;
 }
 
-std::optional<PartitionCowCreator::Return> PartitionCowCreator::Run() {
+std::optional<uint64_t> PartitionCowCreator::GetCowSize(uint64_t snapshot_size) {
+    // TODO: Use |operations|. to determine a minimum COW size.
+    // kCowEstimateFactor is good for prototyping but we can't use that in production.
     static constexpr double kCowEstimateFactor = 1.05;
+    auto cow_size = RoundUp(snapshot_size * kCowEstimateFactor, kDefaultBlockSize);
+    return cow_size;
+}
 
+std::optional<PartitionCowCreator::Return> PartitionCowCreator::Run() {
     CHECK(current_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME &&
           target_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME);
 
@@ -135,13 +144,8 @@
 
     ret.snapshot_status.snapshot_size = *snapshot_size;
 
-    // TODO: always read from cow_size when the COW size is written in
-    // update package. kCowEstimateFactor is good for prototyping but
-    // we can't use that in production.
-    if (!cow_size.has_value()) {
-        cow_size =
-                RoundUp(ret.snapshot_status.snapshot_size * kCowEstimateFactor, kDefaultBlockSize);
-    }
+    auto cow_size = GetCowSize(*snapshot_size);
+    if (!cow_size.has_value()) return std::nullopt;
 
     // Compute regions that are free in both current and target metadata. These are the regions
     // we can use for COW partition.
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.h b/fs_mgr/libsnapshot/partition_cow_creator.h
index a235914..7c81418 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.h
+++ b/fs_mgr/libsnapshot/partition_cow_creator.h
@@ -32,20 +32,23 @@
     using Interval = android::fs_mgr::Interval;
     using MetadataBuilder = android::fs_mgr::MetadataBuilder;
     using Partition = android::fs_mgr::Partition;
+    using InstallOperation = chromeos_update_engine::InstallOperation;
+    template <typename T>
+    using RepeatedPtrField = google::protobuf::RepeatedPtrField<T>;
 
     // The metadata that will be written to target metadata slot.
-    MetadataBuilder* target_metadata;
+    MetadataBuilder* target_metadata = nullptr;
     // The suffix of the target slot.
     std::string target_suffix;
     // The partition in target_metadata that needs to be snapshotted.
-    Partition* target_partition;
+    Partition* target_partition = nullptr;
     // The metadata at the current slot (that would be used if the device boots
     // normally). This is used to determine which extents are being used.
-    MetadataBuilder* current_metadata;
+    MetadataBuilder* current_metadata = nullptr;
     // The suffix of the current slot.
     std::string current_suffix;
-    // The COW size given by client code.
-    std::optional<uint64_t> cow_size;
+    // List of operations to be applied on the partition.
+    const RepeatedPtrField<InstallOperation>* operations = nullptr;
 
     struct Return {
         SnapshotManager::SnapshotStatus snapshot_status;
@@ -57,6 +60,7 @@
   private:
     bool HasExtent(Partition* p, Extent* e);
     std::optional<uint64_t> GetSnapshotSize();
+    std::optional<uint64_t> GetCowSize(uint64_t snapshot_size);
 };
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/partition_cow_creator_test.cpp b/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
index e308943..4c9afff 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
+++ b/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
@@ -18,48 +18,20 @@
 #include <liblp/property_fetcher.h>
 
 #include "partition_cow_creator.h"
+#include "test_helpers.h"
 
 using ::android::fs_mgr::MetadataBuilder;
-using ::testing::_;
-using ::testing::AnyNumber;
-using ::testing::Return;
 
 namespace android {
 namespace snapshot {
 
-class MockPropertyFetcher : public fs_mgr::IPropertyFetcher {
+class PartitionCowCreatorTest : public ::testing::Test {
   public:
-    MOCK_METHOD2(GetProperty, std::string(const std::string&, const std::string&));
-    MOCK_METHOD2(GetBoolProperty, bool(const std::string&, bool));
+    void SetUp() override { SnapshotTestPropertyFetcher::SetUp(); }
+    void TearDown() override { SnapshotTestPropertyFetcher::TearDown(); }
 };
 
-class PartitionCowCreatorTest : ::testing::Test {
-  public:
-    void SetUp() override {
-        fs_mgr::IPropertyFetcher::OverrideForTesting(std::make_unique<MockPropertyFetcher>());
-
-        EXPECT_CALL(fetcher(), GetProperty("ro.boot.slot_suffix", _))
-                .Times(AnyNumber())
-                .WillRepeatedly(Return("_a"));
-        EXPECT_CALL(fetcher(), GetBoolProperty("ro.boot.dynamic_partitions", _))
-                .Times(AnyNumber())
-                .WillRepeatedly(Return(true));
-        EXPECT_CALL(fetcher(), GetBoolProperty("ro.boot.dynamic_partitions_retrofit", _))
-                .Times(AnyNumber())
-                .WillRepeatedly(Return(false));
-        EXPECT_CALL(fetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-                .Times(AnyNumber())
-                .WillRepeatedly(Return(true));
-    }
-    void TearDown() override {
-        fs_mgr::IPropertyFetcher::OverrideForTesting(std::make_unique<MockPropertyFetcher>());
-    }
-    MockPropertyFetcher& fetcher() {
-        return *static_cast<MockPropertyFetcher*>(fs_mgr::IPropertyFetcher::GetInstance());
-    }
-};
-
-TEST(PartitionCowCreator, IntersectSelf) {
+TEST_F(PartitionCowCreatorTest, IntersectSelf) {
     auto builder_a = MetadataBuilder::New(1024 * 1024, 1024, 2);
     ASSERT_NE(builder_a, nullptr);
     auto system_a = builder_a->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
@@ -76,14 +48,11 @@
                                 .target_suffix = "_b",
                                 .target_partition = system_b,
                                 .current_metadata = builder_a.get(),
-                                .current_suffix = "_a",
-                                .cow_size = 20 * 1024};
+                                .current_suffix = "_a"};
     auto ret = creator.Run();
     ASSERT_TRUE(ret.has_value());
     ASSERT_EQ(40 * 1024, ret->snapshot_status.device_size);
     ASSERT_EQ(40 * 1024, ret->snapshot_status.snapshot_size);
-    ASSERT_EQ(20 * 1024,
-              ret->snapshot_status.cow_file_size + ret->snapshot_status.cow_partition_size);
 }
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 15d52f1..2e689bd 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -39,6 +39,7 @@
 #include <liblp/liblp.h>
 
 #include "partition_cow_creator.h"
+#include "snapshot_metadata_updater.h"
 #include "utility.h"
 
 namespace android {
@@ -61,6 +62,10 @@
 using android::fs_mgr::LpMetadata;
 using android::fs_mgr::MetadataBuilder;
 using android::fs_mgr::SlotNumberForSlotSuffix;
+using chromeos_update_engine::DeltaArchiveManifest;
+using chromeos_update_engine::InstallOperation;
+template <typename T>
+using RepeatedPtrField = google::protobuf::RepeatedPtrField<T>;
 using std::chrono::duration_cast;
 using namespace std::chrono_literals;
 using namespace std::string_literals;
@@ -74,6 +79,7 @@
     std::string GetGsidDir() const override { return "ota"s; }
     std::string GetMetadataDir() const override { return "/metadata/ota"s; }
     std::string GetSlotSuffix() const override { return fs_mgr_get_slot_suffix(); }
+    std::string GetOtherSlotSuffix() const override { return fs_mgr_get_other_slot_suffix(); }
     const android::fs_mgr::IPartitionOpener& GetPartitionOpener() const { return opener_; }
     std::string GetSuperDevice(uint32_t slot) const override {
         return fs_mgr_get_super_partition_name(slot);
@@ -125,6 +131,16 @@
 }
 
 bool SnapshotManager::BeginUpdate() {
+    bool needs_merge = false;
+    if (!TryCancelUpdate(&needs_merge)) {
+        return false;
+    }
+    if (needs_merge) {
+        LOG(INFO) << "Wait for merge (if any) before beginning a new update.";
+        auto state = ProcessUpdateState();
+        LOG(INFO) << "Merged with state = " << state;
+    }
+
     auto file = LockExclusive();
     if (!file) return false;
 
@@ -137,6 +153,19 @@
 }
 
 bool SnapshotManager::CancelUpdate() {
+    bool needs_merge = false;
+    if (!TryCancelUpdate(&needs_merge)) {
+        return false;
+    }
+    if (needs_merge) {
+        LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
+    }
+    return !needs_merge;
+}
+
+bool SnapshotManager::TryCancelUpdate(bool* needs_merge) {
+    *needs_merge = false;
+
     auto file = LockExclusive();
     if (!file) return false;
 
@@ -161,8 +190,8 @@
             return RemoveAllUpdateState(file.get());
         }
     }
-    LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
-    return false;
+    *needs_merge = true;
+    return true;
 }
 
 bool SnapshotManager::RemoveAllUpdateState(LockedFile* lock) {
@@ -1453,7 +1482,7 @@
         PLOG(ERROR) << "Open failed: " << file;
         return nullptr;
     }
-    if (flock(fd, lock_flags) < 0) {
+    if (lock_flags != 0 && flock(fd, lock_flags) < 0) {
         PLOG(ERROR) << "Acquire flock failed: " << file;
         return nullptr;
     }
@@ -1520,34 +1549,33 @@
     }
 }
 
-bool SnapshotManager::WriteUpdateState(LockedFile* file, UpdateState state) {
-    std::string contents;
+std::ostream& operator<<(std::ostream& os, UpdateState state) {
     switch (state) {
         case UpdateState::None:
-            contents = "none";
-            break;
+            return os << "none";
         case UpdateState::Initiated:
-            contents = "initiated";
-            break;
+            return os << "initiated";
         case UpdateState::Unverified:
-            contents = "unverified";
-            break;
+            return os << "unverified";
         case UpdateState::Merging:
-            contents = "merging";
-            break;
+            return os << "merging";
         case UpdateState::MergeCompleted:
-            contents = "merge-completed";
-            break;
+            return os << "merge-completed";
         case UpdateState::MergeNeedsReboot:
-            contents = "merge-needs-reboot";
-            break;
+            return os << "merge-needs-reboot";
         case UpdateState::MergeFailed:
-            contents = "merge-failed";
-            break;
+            return os << "merge-failed";
         default:
             LOG(ERROR) << "Unknown update state";
-            return false;
+            return os;
     }
+}
+
+bool SnapshotManager::WriteUpdateState(LockedFile* file, UpdateState state) {
+    std::stringstream ss;
+    ss << state;
+    std::string contents = ss.str();
+    if (contents.empty()) return false;
 
     if (!Truncate(file)) return false;
     if (!android::base::WriteStringToFd(contents, file->fd())) {
@@ -1713,26 +1741,60 @@
     return true;
 }
 
-bool SnapshotManager::CreateUpdateSnapshots(MetadataBuilder* target_metadata,
-                                            const std::string& target_suffix,
-                                            MetadataBuilder* current_metadata,
-                                            const std::string& current_suffix,
-                                            const std::map<std::string, uint64_t>& cow_sizes) {
+static void UnmapAndDeleteCowPartition(MetadataBuilder* current_metadata) {
+    auto& dm = DeviceMapper::Instance();
+    std::vector<std::string> to_delete;
+    for (auto* existing_cow_partition : current_metadata->ListPartitionsInGroup(kCowGroupName)) {
+        if (!dm.DeleteDeviceIfExists(existing_cow_partition->name())) {
+            LOG(WARNING) << existing_cow_partition->name()
+                         << " cannot be unmapped and its space cannot be reclaimed";
+            continue;
+        }
+        to_delete.push_back(existing_cow_partition->name());
+    }
+    for (const auto& name : to_delete) {
+        current_metadata->RemovePartition(name);
+    }
+}
+
+bool SnapshotManager::CreateUpdateSnapshots(const DeltaArchiveManifest& manifest) {
     auto lock = LockExclusive();
     if (!lock) return false;
 
-    // Add _{target_suffix} to COW size map.
-    std::map<std::string, uint64_t> suffixed_cow_sizes;
-    for (const auto& [name, size] : cow_sizes) {
-        suffixed_cow_sizes[name + target_suffix] = size;
+    const auto& opener = device_->GetPartitionOpener();
+    auto current_suffix = device_->GetSlotSuffix();
+    uint32_t current_slot = SlotNumberForSlotSuffix(current_suffix);
+    auto target_suffix = device_->GetOtherSlotSuffix();
+    uint32_t target_slot = SlotNumberForSlotSuffix(target_suffix);
+    auto current_super = device_->GetSuperDevice(current_slot);
+
+    auto current_metadata = MetadataBuilder::New(opener, current_super, current_slot);
+    auto target_metadata =
+            MetadataBuilder::NewForUpdate(opener, current_super, current_slot, target_slot);
+
+    SnapshotMetadataUpdater metadata_updater(target_metadata.get(), target_slot, manifest);
+    if (!metadata_updater.Update()) {
+        LOG(ERROR) << "Cannot calculate new metadata.";
+        return false;
     }
 
-    target_metadata->RemoveGroupAndPartitions(kCowGroupName);
     if (!target_metadata->AddGroup(kCowGroupName, 0)) {
         LOG(ERROR) << "Cannot add group " << kCowGroupName;
         return false;
     }
 
+    std::map<std::string, const RepeatedPtrField<InstallOperation>*> install_operation_map;
+    for (const auto& partition_update : manifest.partitions()) {
+        auto suffixed_name = partition_update.partition_name() + target_suffix;
+        auto&& [it, inserted] = install_operation_map.emplace(std::move(suffixed_name),
+                                                              &partition_update.operations());
+        if (!inserted) {
+            LOG(ERROR) << "Duplicated partition " << partition_update.partition_name()
+                       << " in update manifest.";
+            return false;
+        }
+    }
+
     // TODO(b/134949511): remove this check. Right now, with overlayfs mounted, the scratch
     // partition takes up a big chunk of space in super, causing COW images to be created on
     // retrofit Virtual A/B devices.
@@ -1742,6 +1804,10 @@
         return false;
     }
 
+    // Delete previous COW partitions in current_metadata so that PartitionCowCreator marks those as
+    // free regions.
+    UnmapAndDeleteCowPartition(current_metadata.get());
+
     // Check that all these metadata is not retrofit dynamic partitions. Snapshots on
     // devices with retrofit dynamic partitions does not make sense.
     // This ensures that current_metadata->GetFreeRegions() uses the same device
@@ -1757,18 +1823,16 @@
     // these devices.
     AutoDeviceList created_devices;
 
-    for (auto* target_partition : ListPartitionsWithSuffix(target_metadata, target_suffix)) {
-        std::optional<uint64_t> cow_size = std::nullopt;
-        auto it = suffixed_cow_sizes.find(target_partition->name());
-        if (it != suffixed_cow_sizes.end()) {
-            cow_size = it->second;
-            LOG(INFO) << "Using provided COW size " << *cow_size << " for partition "
-                      << target_partition->name();
+    for (auto* target_partition : ListPartitionsWithSuffix(target_metadata.get(), target_suffix)) {
+        const RepeatedPtrField<InstallOperation>* operations = nullptr;
+        auto operations_it = install_operation_map.find(target_partition->name());
+        if (operations_it != install_operation_map.end()) {
+            operations = operations_it->second;
         }
 
         // Compute the device sizes for the partition.
-        PartitionCowCreator cow_creator{target_metadata,  target_suffix,  target_partition,
-                                        current_metadata, current_suffix, cow_size};
+        PartitionCowCreator cow_creator{target_metadata.get(),  target_suffix,  target_partition,
+                                        current_metadata.get(), current_suffix, operations};
         auto cow_creator_ret = cow_creator.Run();
         if (!cow_creator_ret.has_value()) {
             return false;
@@ -1846,13 +1910,17 @@
 
     auto& dm = DeviceMapper::Instance();
     auto exported_target_metadata = target_metadata->Export();
+    if (exported_target_metadata == nullptr) {
+        LOG(ERROR) << "Cannot export target metadata";
+        return false;
+    }
     CreateLogicalPartitionParams cow_params{
             .block_device = LP_METADATA_DEFAULT_PARTITION_NAME,
             .metadata = exported_target_metadata.get(),
             .timeout_ms = std::chrono::milliseconds::max(),
             .partition_opener = &device_->GetPartitionOpener(),
     };
-    for (auto* target_partition : ListPartitionsWithSuffix(target_metadata, target_suffix)) {
+    for (auto* target_partition : ListPartitionsWithSuffix(target_metadata.get(), target_suffix)) {
         AutoDeviceList created_devices_for_cow;
 
         if (!UnmapPartitionWithSnapshot(lock.get(), target_partition->name())) {
@@ -1884,6 +1952,12 @@
         // Let destructor of created_devices_for_cow to unmap the COW devices.
     };
 
+    if (!UpdatePartitionTable(opener, device_->GetSuperDevice(target_slot),
+                              *exported_target_metadata, target_slot)) {
+        LOG(ERROR) << "Cannot write target metadata";
+        return false;
+    }
+
     created_devices.Release();
     LOG(INFO) << "Successfully created all snapshots for target slot " << target_suffix;
 
@@ -1908,5 +1982,47 @@
     return UnmapPartitionWithSnapshot(lock.get(), target_partition_name);
 }
 
+bool SnapshotManager::Dump(std::ostream& os) {
+    // Don't actually lock. Dump() is for debugging purposes only, so it is okay
+    // if it is racy.
+    auto file = OpenStateFile(O_RDONLY, 0);
+    if (!file) return false;
+
+    std::stringstream ss;
+
+    ss << "Update state: " << ReadUpdateState(file.get()) << std::endl;
+
+    auto boot_file = GetSnapshotBootIndicatorPath();
+    std::string boot_indicator;
+    if (android::base::ReadFileToString(boot_file, &boot_indicator)) {
+        ss << "Boot indicator: old slot = " << boot_indicator << std::endl;
+    }
+
+    bool ok = true;
+    std::vector<std::string> snapshots;
+    if (!ListSnapshots(file.get(), &snapshots)) {
+        LOG(ERROR) << "Could not list snapshots";
+        snapshots.clear();
+        ok = false;
+    }
+    for (const auto& name : snapshots) {
+        ss << "Snapshot: " << name << std::endl;
+        SnapshotStatus status;
+        if (!ReadSnapshotStatus(file.get(), name, &status)) {
+            ok = false;
+            continue;
+        }
+        ss << "    state: " << to_string(status.state) << std::endl;
+        ss << "    device size (bytes): " << status.device_size << std::endl;
+        ss << "    snapshot size (bytes): " << status.snapshot_size << std::endl;
+        ss << "    cow partition size (bytes): " << status.cow_partition_size << std::endl;
+        ss << "    cow file size (bytes): " << status.cow_file_size << std::endl;
+        ss << "    allocated sectors: " << status.sectors_allocated << std::endl;
+        ss << "    metadata sectors: " << status.metadata_sectors << std::endl;
+    }
+    os << ss.rdbuf();
+    return ok;
+}
+
 }  // namespace snapshot
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/snapshot_metadata_updater.cpp b/fs_mgr/libsnapshot/snapshot_metadata_updater.cpp
new file mode 100644
index 0000000..60bf796
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshot_metadata_updater.cpp
@@ -0,0 +1,273 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "snapshot_metadata_updater.h"
+
+#include <algorithm>
+#include <map>
+#include <optional>
+#include <set>
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <android-base/strings.h>
+#include <fs_mgr.h>
+#include <libsnapshot/snapshot.h>
+
+using android::fs_mgr::MetadataBuilder;
+using android::fs_mgr::Partition;
+using android::fs_mgr::SlotSuffixForSlotNumber;
+using chromeos_update_engine::DeltaArchiveManifest;
+
+namespace android {
+namespace snapshot {
+SnapshotMetadataUpdater::SnapshotMetadataUpdater(MetadataBuilder* builder, uint32_t target_slot,
+                                                 const DeltaArchiveManifest& manifest)
+    : builder_(builder), target_suffix_(SlotSuffixForSlotNumber(target_slot)) {
+    if (!manifest.has_dynamic_partition_metadata()) {
+        return;
+    }
+
+    // Key: partition name ("system"). Value: group name ("group").
+    // No suffix.
+    std::map<std::string_view, std::string_view> partition_group_map;
+    const auto& metadata_groups = manifest.dynamic_partition_metadata().groups();
+    groups_.reserve(metadata_groups.size());
+    for (const auto& group : metadata_groups) {
+        groups_.emplace_back(Group{group.name() + target_suffix_, &group});
+        for (const auto& partition_name : group.partition_names()) {
+            partition_group_map[partition_name] = group.name();
+        }
+    }
+
+    for (const auto& p : manifest.partitions()) {
+        auto it = partition_group_map.find(p.partition_name());
+        if (it != partition_group_map.end()) {
+            partitions_.emplace_back(Partition{p.partition_name() + target_suffix_,
+                                               std::string(it->second) + target_suffix_, &p});
+        }
+    }
+}
+
+bool SnapshotMetadataUpdater::ShrinkPartitions() const {
+    for (const auto& partition_update : partitions_) {
+        auto* existing_partition = builder_->FindPartition(partition_update.name);
+        if (existing_partition == nullptr) {
+            continue;
+        }
+        auto new_size = partition_update->new_partition_info().size();
+        if (existing_partition->size() <= new_size) {
+            continue;
+        }
+        if (!builder_->ResizePartition(existing_partition, new_size)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::DeletePartitions() const {
+    std::vector<std::string> partitions_to_delete;
+    // Don't delete partitions in groups where the group name doesn't have target_suffix,
+    // e.g. default.
+    for (auto* existing_partition : ListPartitionsWithSuffix(builder_, target_suffix_)) {
+        auto iter = std::find_if(partitions_.begin(), partitions_.end(),
+                                 [existing_partition](auto&& partition_update) {
+                                     return partition_update.name == existing_partition->name();
+                                 });
+        // Update package metadata doesn't have this partition. Prepare to delete it.
+        // Not deleting from builder_ yet because it may break ListPartitionsWithSuffix if it were
+        // to return an iterable view of builder_.
+        if (iter == partitions_.end()) {
+            partitions_to_delete.push_back(existing_partition->name());
+        }
+    }
+
+    for (const auto& partition_name : partitions_to_delete) {
+        builder_->RemovePartition(partition_name);
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::MovePartitionsToDefault() const {
+    for (const auto& partition_update : partitions_) {
+        auto* existing_partition = builder_->FindPartition(partition_update.name);
+        if (existing_partition == nullptr) {
+            continue;
+        }
+        if (existing_partition->group_name() == partition_update.group_name) {
+            continue;
+        }
+        // Move to "default" group (which doesn't have maximum size constraint)
+        // temporarily.
+        if (!builder_->ChangePartitionGroup(existing_partition, android::fs_mgr::kDefaultGroup)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::ShrinkGroups() const {
+    for (const auto& group_update : groups_) {
+        auto* existing_group = builder_->FindGroup(group_update.name);
+        if (existing_group == nullptr) {
+            continue;
+        }
+        if (existing_group->maximum_size() <= group_update->size()) {
+            continue;
+        }
+        if (!builder_->ChangeGroupSize(existing_group->name(), group_update->size())) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::DeleteGroups() const {
+    std::vector<std::string> existing_groups = builder_->ListGroups();
+    for (const auto& existing_group_name : existing_groups) {
+        // Don't delete groups without target suffix, e.g. default.
+        if (!android::base::EndsWith(existing_group_name, target_suffix_)) {
+            continue;
+        }
+
+        auto iter = std::find_if(groups_.begin(), groups_.end(),
+                                 [&existing_group_name](auto&& group_update) {
+                                     return group_update.name == existing_group_name;
+                                 });
+        // Update package metadata has this group as well, so not deleting it.
+        if (iter != groups_.end()) {
+            continue;
+        }
+        // Update package metadata doesn't have this group. Before deleting it, sanity check that it
+        // doesn't have any partitions left. Update metadata shouldn't assign any partitions to this
+        // group, so all partitions that originally belong to this group should be moved by
+        // MovePartitionsToDefault at this point.
+        auto existing_partitions_in_group = builder_->ListPartitionsInGroup(existing_group_name);
+        if (!existing_partitions_in_group.empty()) {
+            std::vector<std::string> partition_names_in_group;
+            std::transform(existing_partitions_in_group.begin(), existing_partitions_in_group.end(),
+                           std::back_inserter(partition_names_in_group),
+                           [](auto* p) { return p->name(); });
+            LOG(ERROR)
+                    << "Group " << existing_group_name
+                    << " cannot be deleted because the following partitions are left unassigned: ["
+                    << android::base::Join(partition_names_in_group, ",") << "]";
+            return false;
+        }
+        builder_->RemoveGroupAndPartitions(existing_group_name);
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::AddGroups() const {
+    for (const auto& group_update : groups_) {
+        if (builder_->FindGroup(group_update.name) == nullptr) {
+            if (!builder_->AddGroup(group_update.name, group_update->size())) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::GrowGroups() const {
+    for (const auto& group_update : groups_) {
+        auto* existing_group = builder_->FindGroup(group_update.name);
+        if (existing_group == nullptr) {
+            continue;
+        }
+        if (existing_group->maximum_size() >= group_update->size()) {
+            continue;
+        }
+        if (!builder_->ChangeGroupSize(existing_group->name(), group_update->size())) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::AddPartitions() const {
+    for (const auto& partition_update : partitions_) {
+        if (builder_->FindPartition(partition_update.name) == nullptr) {
+            auto* p =
+                    builder_->AddPartition(partition_update.name, partition_update.group_name,
+                                           LP_PARTITION_ATTR_READONLY | LP_PARTITION_ATTR_UPDATED);
+            if (p == nullptr) {
+                return false;
+            }
+        }
+    }
+    // Will be resized in GrowPartitions.
+    return true;
+}
+
+bool SnapshotMetadataUpdater::GrowPartitions() const {
+    for (const auto& partition_update : partitions_) {
+        auto* existing_partition = builder_->FindPartition(partition_update.name);
+        if (existing_partition == nullptr) {
+            continue;
+        }
+        auto new_size = partition_update->new_partition_info().size();
+        if (existing_partition->size() >= new_size) {
+            continue;
+        }
+        if (!builder_->ResizePartition(existing_partition, new_size)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::MovePartitionsToCorrectGroup() const {
+    for (const auto& partition_update : partitions_) {
+        auto* existing_partition = builder_->FindPartition(partition_update.name);
+        if (existing_partition == nullptr) {
+            continue;
+        }
+        if (existing_partition->group_name() == partition_update.group_name) {
+            continue;
+        }
+        if (!builder_->ChangePartitionGroup(existing_partition, partition_update.group_name)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool SnapshotMetadataUpdater::Update() const {
+    // Remove extents used by COW devices by removing the COW group completely.
+    builder_->RemoveGroupAndPartitions(android::snapshot::kCowGroupName);
+
+    // The order of these operations are important so that we
+    // always have enough space to grow or add new partitions / groups.
+    // clang-format off
+    return ShrinkPartitions() &&
+           DeletePartitions() &&
+           MovePartitionsToDefault() &&
+           ShrinkGroups() &&
+           DeleteGroups() &&
+           AddGroups() &&
+           GrowGroups() &&
+           AddPartitions() &&
+           GrowPartitions() &&
+           MovePartitionsToCorrectGroup();
+    // clang-format on
+}
+}  // namespace snapshot
+}  // namespace android
diff --git a/fs_mgr/libsnapshot/snapshot_metadata_updater.h b/fs_mgr/libsnapshot/snapshot_metadata_updater.h
new file mode 100644
index 0000000..83c9460
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshot_metadata_updater.h
@@ -0,0 +1,85 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#pragma once
+
+#include <stdint.h>
+
+#include <string>
+#include <vector>
+
+#include <liblp/builder.h>
+#include <update_engine/update_metadata.pb.h>
+
+#include "utility.h"
+
+namespace android {
+namespace snapshot {
+
+// Helper class that modifies a super partition metadata for an update for
+// Virtual A/B devices.
+class SnapshotMetadataUpdater {
+    using DeltaArchiveManifest = chromeos_update_engine::DeltaArchiveManifest;
+    using DynamicPartitionMetadata = chromeos_update_engine::DynamicPartitionMetadata;
+    using DynamicPartitionGroup = chromeos_update_engine::DynamicPartitionGroup;
+    using PartitionUpdate = chromeos_update_engine::PartitionUpdate;
+
+  public:
+    // Caller is responsible for ensuring the lifetime of manifest to be longer
+    // than SnapshotMetadataUpdater.
+    SnapshotMetadataUpdater(android::fs_mgr::MetadataBuilder* builder, uint32_t target_slot,
+                            const DeltaArchiveManifest& manifest);
+    bool Update() const;
+
+  private:
+    bool RenameGroupSuffix() const;
+    bool ShrinkPartitions() const;
+    bool DeletePartitions() const;
+    bool MovePartitionsToDefault() const;
+    bool ShrinkGroups() const;
+    bool DeleteGroups() const;
+    bool AddGroups() const;
+    bool GrowGroups() const;
+    bool AddPartitions() const;
+    bool GrowPartitions() const;
+    bool MovePartitionsToCorrectGroup() const;
+
+    // Wraps a DynamicPartitionGroup with a slot-suffixed name. Always use
+    // .name instead of ->name() because .name has the slot suffix (e.g.
+    // .name is "group_b" and ->name() is "group".)
+    struct Group {
+        std::string name;
+        const DynamicPartitionGroup* group;
+        const DynamicPartitionGroup* operator->() const { return group; }
+    };
+    // Wraps a PartitionUpdate with a slot-suffixed name / group name. Always use
+    // .name instead of ->partition_name() because .name has the slot suffix (e.g.
+    // .name is "system_b" and ->partition_name() is "system".)
+    struct Partition {
+        std::string name;
+        std::string group_name;
+        const PartitionUpdate* partition;
+        const PartitionUpdate* operator->() const { return partition; }
+    };
+
+    android::fs_mgr::MetadataBuilder* const builder_;
+    const std::string target_suffix_;
+    std::vector<Group> groups_;
+    std::vector<Partition> partitions_;
+};
+
+}  // namespace snapshot
+}  // namespace android
diff --git a/fs_mgr/libsnapshot/snapshot_metadata_updater_test.cpp b/fs_mgr/libsnapshot/snapshot_metadata_updater_test.cpp
new file mode 100644
index 0000000..7d96a67
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshot_metadata_updater_test.cpp
@@ -0,0 +1,331 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "snapshot_metadata_updater.h"
+
+#include <memory>
+#include <string>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <liblp/builder.h>
+#include <storage_literals/storage_literals.h>
+
+#include "test_helpers.h"
+
+using namespace android::storage_literals;
+using android::fs_mgr::LpMetadata;
+using android::fs_mgr::MetadataBuilder;
+using android::fs_mgr::SlotSuffixForSlotNumber;
+using chromeos_update_engine::DeltaArchiveManifest;
+using chromeos_update_engine::DynamicPartitionGroup;
+using chromeos_update_engine::PartitionUpdate;
+using testing::AssertionFailure;
+using testing::AssertionResult;
+using testing::AssertionSuccess;
+
+namespace android {
+namespace snapshot {
+
+class SnapshotMetadataUpdaterTest : public ::testing::TestWithParam<uint32_t> {
+  public:
+    void SetUp() override {
+        target_slot_ = GetParam();
+        target_suffix_ = SlotSuffixForSlotNumber(target_slot_);
+        SnapshotTestPropertyFetcher::SetUp(SlotSuffixForSlotNumber(1 - target_slot_));
+        builder_ = MetadataBuilder::New(4_GiB + 1_MiB, 4_KiB, 2);
+
+        group_ = manifest_.mutable_dynamic_partition_metadata()->add_groups();
+        group_->set_name("group");
+        group_->set_size(4_GiB);
+        group_->add_partition_names("system");
+        group_->add_partition_names("vendor");
+        system_ = manifest_.add_partitions();
+        system_->set_partition_name("system");
+        SetSize(system_, 2_GiB);
+        vendor_ = manifest_.add_partitions();
+        vendor_->set_partition_name("vendor");
+        SetSize(vendor_, 1_GiB);
+
+        ASSERT_TRUE(FillFakeMetadata(builder_.get(), manifest_, target_suffix_));
+    }
+
+    void TearDown() override { SnapshotTestPropertyFetcher::TearDown(); }
+
+    // Append suffix to name.
+    std::string T(std::string_view name) { return std::string(name) + target_suffix_; }
+
+    AssertionResult UpdateAndExport() {
+        SnapshotMetadataUpdater updater(builder_.get(), target_slot_, manifest_);
+        if (!updater.Update()) {
+            return AssertionFailure() << "Update failed.";
+        }
+
+        exported_ = builder_->Export();
+        if (exported_ == nullptr) {
+            return AssertionFailure() << "Export failed.";
+        }
+        return AssertionSuccess();
+    }
+
+    // Check that in |builder_|, partition |name| + |target_suffix_| has the given |size|.
+    AssertionResult CheckSize(std::string_view name, uint64_t size) {
+        auto p = builder_->FindPartition(T(name));
+        if (p == nullptr) {
+            return AssertionFailure() << "Cannot find partition " << T(name);
+        }
+        if (p->size() != size) {
+            return AssertionFailure() << "Partition " << T(name) << " should be " << size
+                                      << " bytes, but is " << p->size() << " bytes.";
+        }
+        return AssertionSuccess() << "Partition" << T(name) << " is " << size << " bytes.";
+    }
+
+    // Check that in |builder_|, group |name| + |target_suffix_| has the given |size|.
+    AssertionResult CheckGroupSize(std::string_view name, uint64_t size) {
+        auto g = builder_->FindGroup(T(name));
+        if (g == nullptr) {
+            return AssertionFailure() << "Cannot find group " << T(name);
+        }
+        if (g->maximum_size() != size) {
+            return AssertionFailure() << "Group " << T(name) << " should be " << size
+                                      << " bytes, but is " << g->maximum_size() << " bytes.";
+        }
+        return AssertionSuccess() << "Group" << T(name) << " is " << size << " bytes.";
+    }
+
+    // Check that in |builder_|, partition |partition_name| + |target_suffix_| is in group
+    // |group_name| + |target_suffix_|;
+    AssertionResult CheckGroupName(std::string_view partition_name, std::string_view group_name) {
+        auto p = builder_->FindPartition(T(partition_name));
+        if (p == nullptr) {
+            return AssertionFailure() << "Cannot find partition " << T(partition_name);
+        }
+        if (p->group_name() != T(group_name)) {
+            return AssertionFailure() << "Partition " << T(partition_name) << " should be in "
+                                      << T(group_name) << ", but is in " << p->group_name() << ".";
+        }
+        return AssertionSuccess() << "Partition" << T(partition_name) << " is in " << T(group_name)
+                                  << ".";
+    }
+
+    std::unique_ptr<MetadataBuilder> builder_;
+    uint32_t target_slot_;
+    std::string target_suffix_;
+    DeltaArchiveManifest manifest_;
+    std::unique_ptr<LpMetadata> exported_;
+    DynamicPartitionGroup* group_ = nullptr;
+    PartitionUpdate* system_ = nullptr;
+    PartitionUpdate* vendor_ = nullptr;
+};
+
+TEST_P(SnapshotMetadataUpdaterTest, NoChange) {
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckGroupSize("group", 4_GiB));
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_TRUE(CheckGroupName("system", "group"));
+    EXPECT_TRUE(CheckSize("vendor", 1_GiB));
+    EXPECT_TRUE(CheckGroupName("vendor", "group"));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, GrowWithinBounds) {
+    SetSize(system_, 2_GiB + 512_MiB);
+    SetSize(vendor_, 1_GiB + 512_MiB);
+
+    ASSERT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB + 512_MiB));
+    EXPECT_TRUE(CheckSize("vendor", 1_GiB + 512_MiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, GrowOverSuper) {
+    SetSize(system_, 3_GiB);
+    SetSize(vendor_, 1_GiB + 512_MiB);
+
+    EXPECT_FALSE(UpdateAndExport());
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, GrowOverGroup) {
+    SetSize(system_, 3_GiB);
+    SetSize(vendor_, 1_GiB + 4_KiB);
+
+    EXPECT_FALSE(UpdateAndExport());
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, Add) {
+    group_->add_partition_names("product");
+    auto product = manifest_.add_partitions();
+    product->set_partition_name("product");
+    SetSize(product, 1_GiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_TRUE(CheckSize("vendor", 1_GiB));
+    EXPECT_TRUE(CheckSize("product", 1_GiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, AddTooBig) {
+    group_->add_partition_names("product");
+    auto product = manifest_.add_partitions();
+    product->set_partition_name("product");
+    SetSize(product, 1_GiB + 4_KiB);
+
+    EXPECT_FALSE(UpdateAndExport());
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, ShrinkAll) {
+    SetSize(system_, 1_GiB);
+    SetSize(vendor_, 512_MiB);
+
+    ASSERT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 1_GiB));
+    EXPECT_TRUE(CheckSize("vendor", 512_MiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, ShrinkAndGrow) {
+    SetSize(system_, 3_GiB + 512_MiB);
+    SetSize(vendor_, 512_MiB);
+
+    ASSERT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 3_GiB + 512_MiB));
+    EXPECT_TRUE(CheckSize("vendor", 512_MiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, ShrinkAndAdd) {
+    SetSize(system_, 2_GiB);
+    SetSize(vendor_, 512_MiB);
+    group_->add_partition_names("product");
+    auto product = manifest_.add_partitions();
+    product->set_partition_name("product");
+    SetSize(product, 1_GiB + 512_MiB);
+
+    ASSERT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_TRUE(CheckSize("vendor", 512_MiB));
+    EXPECT_TRUE(CheckSize("product", 1_GiB + 512_MiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, Delete) {
+    group_->mutable_partition_names()->RemoveLast();
+    // No need to delete it from manifest.partitions as SnapshotMetadataUpdater
+    // should ignore them (treat them as static partitions).
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_EQ(nullptr, builder_->FindPartition(T("vendor")));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, DeleteAndGrow) {
+    group_->mutable_partition_names()->RemoveLast();
+    SetSize(system_, 4_GiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 4_GiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, DeleteAndAdd) {
+    group_->mutable_partition_names()->RemoveLast();
+    group_->add_partition_names("product");
+    auto product = manifest_.add_partitions();
+    product->set_partition_name("product");
+    SetSize(product, 2_GiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_EQ(nullptr, builder_->FindPartition(T("vendor")));
+    EXPECT_TRUE(CheckSize("product", 2_GiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, GrowGroup) {
+    group_->set_size(4_GiB + 512_KiB);
+    SetSize(system_, 2_GiB + 256_KiB);
+    SetSize(vendor_, 2_GiB + 256_KiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 2_GiB + 256_KiB));
+    EXPECT_TRUE(CheckSize("vendor", 2_GiB + 256_KiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, ShrinkGroup) {
+    group_->set_size(1_GiB);
+    SetSize(system_, 512_MiB);
+    SetSize(vendor_, 512_MiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckSize("system", 512_MiB));
+    EXPECT_TRUE(CheckSize("vendor", 512_MiB));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, MoveToNewGroup) {
+    group_->mutable_partition_names()->RemoveLast();
+    group_->set_size(2_GiB);
+
+    auto another_group = manifest_.mutable_dynamic_partition_metadata()->add_groups();
+    another_group->set_name("another_group");
+    another_group->set_size(2_GiB);
+    another_group->add_partition_names("vendor");
+    SetSize(vendor_, 2_GiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_TRUE(CheckGroupSize("group", 2_GiB));
+    EXPECT_TRUE(CheckGroupSize("another_group", 2_GiB));
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_TRUE(CheckGroupName("system", "group"));
+    EXPECT_TRUE(CheckSize("vendor", 2_GiB));
+    EXPECT_TRUE(CheckGroupName("vendor", "another_group"));
+}
+
+TEST_P(SnapshotMetadataUpdaterTest, DeleteAndAddGroup) {
+    manifest_.mutable_dynamic_partition_metadata()->mutable_groups()->RemoveLast();
+    group_ = nullptr;
+
+    auto another_group = manifest_.mutable_dynamic_partition_metadata()->add_groups();
+    another_group->set_name("another_group");
+    another_group->set_size(4_GiB);
+    another_group->add_partition_names("system");
+    another_group->add_partition_names("vendor");
+    another_group->add_partition_names("product");
+    auto product = manifest_.add_partitions();
+    product->set_partition_name("product");
+    SetSize(product, 1_GiB);
+
+    EXPECT_TRUE(UpdateAndExport());
+
+    EXPECT_EQ(nullptr, builder_->FindGroup(T("group")));
+    EXPECT_TRUE(CheckGroupSize("another_group", 4_GiB));
+    EXPECT_TRUE(CheckSize("system", 2_GiB));
+    EXPECT_TRUE(CheckGroupName("system", "another_group"));
+    EXPECT_TRUE(CheckSize("vendor", 1_GiB));
+    EXPECT_TRUE(CheckGroupName("vendor", "another_group"));
+    EXPECT_TRUE(CheckSize("product", 1_GiB));
+    EXPECT_TRUE(CheckGroupName("product", "another_group"));
+}
+
+INSTANTIATE_TEST_SUITE_P(, SnapshotMetadataUpdaterTest, testing::Values(0, 1));
+
+}  // namespace snapshot
+}  // namespace android
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index e9835d0..c94fde5 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -31,7 +31,6 @@
 #include <libdm/dm.h>
 #include <libfiemap/image_manager.h>
 #include <liblp/builder.h>
-#include <liblp/mock_property_fetcher.h>
 #include <storage_literals/storage_literals.h>
 
 #include "test_helpers.h"
@@ -47,11 +46,14 @@
 using android::fs_mgr::BlockDeviceInfo;
 using android::fs_mgr::CreateLogicalPartitionParams;
 using android::fs_mgr::DestroyLogicalPartition;
+using android::fs_mgr::Extent;
 using android::fs_mgr::GetPartitionGroupName;
 using android::fs_mgr::GetPartitionName;
+using android::fs_mgr::Interval;
 using android::fs_mgr::MetadataBuilder;
+using chromeos_update_engine::DeltaArchiveManifest;
+using chromeos_update_engine::PartitionUpdate;
 using namespace ::testing;
-using namespace android::fs_mgr::testing;
 using namespace android::storage_literals;
 using namespace std::chrono_literals;
 using namespace std::string_literals;
@@ -62,7 +64,8 @@
 TestDeviceInfo* test_device = nullptr;
 std::string fake_super;
 
-static constexpr uint64_t kSuperSize = 16_MiB;
+static constexpr uint64_t kSuperSize = 16_MiB + 4_KiB;
+static constexpr uint64_t kGroupSize = 16_MiB;
 
 class SnapshotTest : public ::testing::Test {
   public:
@@ -76,7 +79,7 @@
 
   protected:
     void SetUp() override {
-        ResetMockPropertyFetcher();
+        SnapshotTestPropertyFetcher::SetUp();
         InitializeState();
         CleanupTestArtifacts();
         FormatFakeSuper();
@@ -88,7 +91,7 @@
         lock_ = nullptr;
 
         CleanupTestArtifacts();
-        ResetMockPropertyFetcher();
+        SnapshotTestPropertyFetcher::TearDown();
     }
 
     void InitializeState() {
@@ -370,9 +373,6 @@
 }
 
 TEST_F(SnapshotTest, Merge) {
-    ON_CALL(*GetMockedPropertyFetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-            .WillByDefault(Return(true));
-
     ASSERT_TRUE(AcquireLock());
 
     static const uint64_t kDeviceSize = 1024 * 1024;
@@ -490,9 +490,6 @@
 }
 
 TEST_F(SnapshotTest, FirstStageMountAndMerge) {
-    ON_CALL(*GetMockedPropertyFetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-            .WillByDefault(Return(true));
-
     ASSERT_TRUE(AcquireLock());
 
     static const uint64_t kDeviceSize = 1024 * 1024;
@@ -510,10 +507,7 @@
     ASSERT_TRUE(sm->FinishedSnapshotWrites());
     ASSERT_TRUE(DestroyLogicalPartition("test_partition_b-base"));
 
-    auto rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_b");
-
-    auto init = SnapshotManager::NewForFirstStageMount(rebooted);
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -532,9 +526,6 @@
 }
 
 TEST_F(SnapshotTest, FlashSuperDuringUpdate) {
-    ON_CALL(*GetMockedPropertyFetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-            .WillByDefault(Return(true));
-
     ASSERT_TRUE(AcquireLock());
 
     static const uint64_t kDeviceSize = 1024 * 1024;
@@ -556,10 +547,7 @@
     FormatFakeSuper();
     ASSERT_TRUE(CreatePartition("test_partition_b", kDeviceSize));
 
-    auto rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_b");
-
-    auto init = SnapshotManager::NewForFirstStageMount(rebooted);
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -580,9 +568,6 @@
 }
 
 TEST_F(SnapshotTest, FlashSuperDuringMerge) {
-    ON_CALL(*GetMockedPropertyFetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-            .WillByDefault(Return(true));
-
     ASSERT_TRUE(AcquireLock());
 
     static const uint64_t kDeviceSize = 1024 * 1024;
@@ -600,10 +585,7 @@
     ASSERT_TRUE(sm->FinishedSnapshotWrites());
     ASSERT_TRUE(DestroyLogicalPartition("test_partition_b-base"));
 
-    auto rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_b");
-
-    auto init = SnapshotManager::NewForFirstStageMount(rebooted);
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -633,31 +615,39 @@
         // Cleanup() changes slot suffix, so initialize it again.
         test_device->set_slot_suffix("_a");
 
-        ON_CALL(*GetMockedPropertyFetcher(), GetBoolProperty("ro.virtual_ab.enabled", _))
-                .WillByDefault(Return(true));
+        opener_ = std::make_unique<TestPartitionOpener>(fake_super);
 
-        opener = std::make_unique<TestPartitionOpener>(fake_super);
-
-        // Initialize source partition metadata. sys_b is similar to system_other.
+        // Create a fake update package metadata.
         // Not using full name "system", "vendor", "product" because these names collide with the
         // mapped partitions on the running device.
-        src = MetadataBuilder::New(*opener, "super", 0);
-        ASSERT_NE(nullptr, src);
-        auto partition = src->AddPartition("sys_a", 0);
+        // Each test modifies manifest_ slightly to indicate changes to the partition layout.
+        auto group = manifest_.mutable_dynamic_partition_metadata()->add_groups();
+        group->set_name("group");
+        group->set_size(kGroupSize);
+        group->add_partition_names("sys");
+        group->add_partition_names("vnd");
+        group->add_partition_names("prd");
+        sys_ = manifest_.add_partitions();
+        sys_->set_partition_name("sys");
+        SetSize(sys_, 3_MiB);
+        vnd_ = manifest_.add_partitions();
+        vnd_->set_partition_name("vnd");
+        SetSize(vnd_, 3_MiB);
+        prd_ = manifest_.add_partitions();
+        prd_->set_partition_name("prd");
+        SetSize(prd_, 3_MiB);
+
+        // Initialize source partition metadata using |manifest_|.
+        src_ = MetadataBuilder::New(*opener_, "super", 0);
+        ASSERT_TRUE(FillFakeMetadata(src_.get(), manifest_, "_a"));
+        ASSERT_NE(nullptr, src_);
+        // Add sys_b which is like system_other.
+        auto partition = src_->AddPartition("sys_b", 0);
         ASSERT_NE(nullptr, partition);
-        ASSERT_TRUE(src->ResizePartition(partition, 3_MiB));
-        partition = src->AddPartition("vnd_a", 0);
-        ASSERT_NE(nullptr, partition);
-        ASSERT_TRUE(src->ResizePartition(partition, 3_MiB));
-        partition = src->AddPartition("prd_a", 0);
-        ASSERT_NE(nullptr, partition);
-        ASSERT_TRUE(src->ResizePartition(partition, 3_MiB));
-        partition = src->AddPartition("sys_b", 0);
-        ASSERT_NE(nullptr, partition);
-        ASSERT_TRUE(src->ResizePartition(partition, 1_MiB));
-        auto metadata = src->Export();
+        ASSERT_TRUE(src_->ResizePartition(partition, 1_MiB));
+        auto metadata = src_->Export();
         ASSERT_NE(nullptr, metadata);
-        ASSERT_TRUE(UpdatePartitionTable(*opener, "super", *metadata.get(), 0));
+        ASSERT_TRUE(UpdatePartitionTable(*opener_, "super", *metadata.get(), 0));
 
         // Map source partitions. Additionally, map sys_b to simulate system_other after flashing.
         std::string path;
@@ -668,7 +658,7 @@
                             .metadata_slot = 0,
                             .partition_name = name,
                             .timeout_ms = 1s,
-                            .partition_opener = opener.get(),
+                            .partition_opener = opener_.get(),
                     },
                     &path));
             ASSERT_TRUE(WriteRandomData(path));
@@ -692,22 +682,6 @@
         EXPECT_TRUE(UnmapAll());
     }
 
-    static AssertionResult ResizePartitions(
-            MetadataBuilder* builder,
-            const std::vector<std::pair<std::string, uint64_t>>& partition_sizes) {
-        for (auto&& [name, size] : partition_sizes) {
-            auto partition = builder->FindPartition(name);
-            if (!partition) {
-                return AssertionFailure() << "Cannot find partition in metadata " << name;
-            }
-            if (!builder->ResizePartition(partition, size)) {
-                return AssertionFailure()
-                       << "Cannot resize partition " << name << " to " << size << " bytes";
-            }
-        }
-        return AssertionSuccess();
-    }
-
     AssertionResult IsPartitionUnchanged(const std::string& name) {
         std::string path;
         if (!dm_.GetDmDevicePathByName(name, &path)) {
@@ -748,9 +722,14 @@
         return AssertionSuccess();
     }
 
-    std::unique_ptr<TestPartitionOpener> opener;
-    std::unique_ptr<MetadataBuilder> src;
+    std::unique_ptr<TestPartitionOpener> opener_;
+    DeltaArchiveManifest manifest_;
+    std::unique_ptr<MetadataBuilder> src_;
     std::map<std::string, std::string> hashes_;
+
+    PartitionUpdate* sys_ = nullptr;
+    PartitionUpdate* vnd_ = nullptr;
+    PartitionUpdate* prd_ = nullptr;
 };
 
 // Test full update flow executed by update_engine. Some partitions uses super empty space,
@@ -758,38 +737,26 @@
 // Also test UnmapUpdateSnapshot unmaps everything.
 // Also test first stage mount and merge after this.
 TEST_F(SnapshotUpdateTest, FullUpdateFlow) {
-    // OTA client calls CancelUpdate then BeginUpdate before doing anything.
-    ASSERT_TRUE(sm->CancelUpdate());
-    ASSERT_TRUE(sm->BeginUpdate());
-
     // OTA client blindly unmaps all partitions that are possibly mapped.
     for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
         ASSERT_TRUE(sm->UnmapUpdateSnapshot(name));
     }
 
-    // OTA client adjusts the partition sizes before giving it to CreateUpdateSnapshots.
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    // clang-format off
-    ASSERT_TRUE(ResizePartitions(tgt.get(), {
-            {"sys_b", 4_MiB}, // grows
-            {"vnd_b", 4_MiB}, // grows
-            {"prd_b", 4_MiB}, // grows
-    }));
-    // clang-format on
+    // Grow all partitions.
+    SetSize(sys_, 4_MiB);
+    SetSize(vnd_, 4_MiB);
+    SetSize(prd_, 4_MiB);
 
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
+    // Execute the update.
+    ASSERT_TRUE(sm->BeginUpdate());
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
 
     // Test that partitions prioritize using space in super.
+    auto tgt = MetadataBuilder::New(*opener_, "super", 1);
     ASSERT_NE(nullptr, tgt->FindPartition("sys_b-cow"));
     ASSERT_NE(nullptr, tgt->FindPartition("vnd_b-cow"));
     ASSERT_EQ(nullptr, tgt->FindPartition("prd_b-cow"));
 
-    // The metadata slot 1 is now updated.
-    auto metadata = tgt->Export();
-    ASSERT_NE(nullptr, metadata);
-    ASSERT_TRUE(UpdatePartitionTable(*opener, "super", *metadata.get(), 1));
-
     // Write some data to target partitions.
     for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
         std::string path;
@@ -799,7 +766,7 @@
                         .metadata_slot = 1,
                         .partition_name = name,
                         .timeout_ms = 10s,
-                        .partition_opener = opener.get(),
+                        .partition_opener = opener_.get(),
                 },
                 &path))
                 << name;
@@ -820,9 +787,7 @@
     ASSERT_TRUE(UnmapAll());
 
     // After reboot, init does first stage mount.
-    auto rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_b");
-    auto init = SnapshotManager::NewForFirstStageMount(rebooted);
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -845,49 +810,31 @@
 
 // Test that if new system partitions uses empty space in super, that region is not snapshotted.
 TEST_F(SnapshotUpdateTest, DirectWriteEmptySpace) {
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    // clang-format off
-    ASSERT_TRUE(ResizePartitions(tgt.get(), {
-            {"sys_b", 4_MiB}, // grows
-            // vnd_b and prd_b are unchanged
-    }));
-    // clang-format on
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
-
+    SetSize(sys_, 4_MiB);
+    // vnd_b and prd_b are unchanged.
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
     ASSERT_EQ(3_MiB, GetSnapshotSize("sys_b").value_or(0));
 }
 
 // Test that if new system partitions uses space of old vendor partition, that region is
 // snapshotted.
 TEST_F(SnapshotUpdateTest, SnapshotOldPartitions) {
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    // clang-format off
-    ASSERT_TRUE(ResizePartitions(tgt.get(), {
-            {"vnd_b", 2_MiB}, // shrinks
-            {"sys_b", 4_MiB}, // grows
-            // prd_b is unchanged
-    }));
-    // clang-format on
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
-
+    SetSize(sys_, 4_MiB);  // grows
+    SetSize(vnd_, 2_MiB);  // shrinks
+    // prd_b is unchanged
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
     ASSERT_EQ(4_MiB, GetSnapshotSize("sys_b").value_or(0));
 }
 
 // Test that even if there seem to be empty space in target metadata, COW partition won't take
 // it because they are used by old partitions.
 TEST_F(SnapshotUpdateTest, CowPartitionDoNotTakeOldPartitions) {
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    // clang-format off
-    ASSERT_TRUE(ResizePartitions(tgt.get(), {
-            {"sys_b", 2_MiB}, // shrinks
-            // vnd_b and prd_b are unchanged
-    }));
-    // clang-format on
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
+    SetSize(sys_, 2_MiB);  // shrinks
+    // vnd_b and prd_b are unchanged.
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
 
+    auto tgt = MetadataBuilder::New(*opener_, "super", 1);
+    ASSERT_NE(nullptr, tgt);
     auto metadata = tgt->Export();
     ASSERT_NE(nullptr, metadata);
     std::vector<std::string> written;
@@ -903,7 +850,7 @@
                         .metadata = metadata.get(),
                         .partition = &p,
                         .timeout_ms = 1s,
-                        .partition_opener = opener.get(),
+                        .partition_opener = opener_.get(),
                 },
                 &path));
         ASSERT_TRUE(WriteRandomData(path));
@@ -934,14 +881,8 @@
     // Redo the update.
     ASSERT_TRUE(sm->BeginUpdate());
     ASSERT_TRUE(sm->UnmapUpdateSnapshot("sys_b"));
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
 
-    // The metadata slot 1 is now updated.
-    auto metadata = tgt->Export();
-    ASSERT_NE(nullptr, metadata);
-    ASSERT_TRUE(UpdatePartitionTable(*opener, "super", *metadata.get(), 1));
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
 
     // Check that target partitions can be mapped.
     for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
@@ -952,7 +893,7 @@
                         .metadata_slot = 1,
                         .partition_name = name,
                         .timeout_ms = 10s,
-                        .partition_opener = opener.get(),
+                        .partition_opener = opener_.get(),
                 },
                 &path))
                 << name;
@@ -964,14 +905,8 @@
     // Execute the update.
     ASSERT_TRUE(sm->BeginUpdate());
     ASSERT_TRUE(sm->UnmapUpdateSnapshot("sys_b"));
-    auto tgt = MetadataBuilder::NewForUpdate(*opener, "super", 0, 1);
-    ASSERT_NE(nullptr, tgt);
-    ASSERT_TRUE(sm->CreateUpdateSnapshots(tgt.get(), "_b", src.get(), "_a", {}));
 
-    // The metadata slot 1 is now updated.
-    auto metadata = tgt->Export();
-    ASSERT_NE(nullptr, metadata);
-    ASSERT_TRUE(UpdatePartitionTable(*opener, "super", *metadata.get(), 1));
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
 
     // Write some data to target partitions.
     for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
@@ -982,7 +917,7 @@
                         .metadata_slot = 1,
                         .partition_name = name,
                         .timeout_ms = 10s,
-                        .partition_opener = opener.get(),
+                        .partition_opener = opener_.get(),
                 },
                 &path))
                 << name;
@@ -1003,9 +938,7 @@
     ASSERT_TRUE(UnmapAll());
 
     // After reboot, init does first stage mount.
-    auto rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_b");
-    auto init = SnapshotManager::NewForFirstStageMount(rebooted);
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -1017,9 +950,7 @@
 
     // Simulate shutting down the device again.
     ASSERT_TRUE(UnmapAll());
-    rebooted = new TestDeviceInfo(fake_super);
-    rebooted->set_slot_suffix("_a");
-    init = SnapshotManager::NewForFirstStageMount(rebooted);
+    init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_a"));
     ASSERT_NE(init, nullptr);
     ASSERT_FALSE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
@@ -1037,6 +968,57 @@
     ASSERT_TRUE(sm->CancelUpdate());
 }
 
+static std::vector<Interval> ToIntervals(const std::vector<std::unique_ptr<Extent>>& extents) {
+    std::vector<Interval> ret;
+    std::transform(extents.begin(), extents.end(), std::back_inserter(ret),
+                   [](const auto& extent) { return extent->AsLinearExtent()->AsInterval(); });
+    return ret;
+}
+
+// Test that at the second update, old COW partition spaces are reclaimed.
+TEST_F(SnapshotUpdateTest, ReclaimCow) {
+    // Execute the first update.
+    ASSERT_TRUE(sm->BeginUpdate());
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
+    ASSERT_TRUE(sm->FinishedSnapshotWrites());
+
+    // Simulate shutting down the device.
+    ASSERT_TRUE(UnmapAll());
+
+    // After reboot, init does first stage mount.
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
+    ASSERT_NE(init, nullptr);
+    ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
+    ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super"));
+    init = nullptr;
+
+    // Initiate the merge and wait for it to be completed.
+    auto new_sm = SnapshotManager::New(new TestDeviceInfo(fake_super, "_b"));
+    ASSERT_TRUE(new_sm->InitiateMerge());
+    ASSERT_EQ(UpdateState::MergeCompleted, new_sm->ProcessUpdateState());
+
+    // Execute the second update.
+    ASSERT_TRUE(new_sm->BeginUpdate());
+    ASSERT_TRUE(new_sm->CreateUpdateSnapshots(manifest_));
+
+    // Check that the old COW space is reclaimed and does not occupy space of mapped partitions.
+    auto src = MetadataBuilder::New(*opener_, "super", 1);
+    auto tgt = MetadataBuilder::New(*opener_, "super", 0);
+    for (const auto& cow_part_name : {"sys_a-cow", "vnd_a-cow", "prd_a-cow"}) {
+        auto* cow_part = tgt->FindPartition(cow_part_name);
+        ASSERT_NE(nullptr, cow_part) << cow_part_name << " does not exist in target metadata";
+        auto cow_intervals = ToIntervals(cow_part->extents());
+        for (const auto& old_part_name : {"sys_b", "vnd_b", "prd_b"}) {
+            auto* old_part = src->FindPartition(old_part_name);
+            ASSERT_NE(nullptr, old_part) << old_part_name << " does not exist in source metadata";
+            auto old_intervals = ToIntervals(old_part->extents());
+
+            auto intersect = Interval::Intersect(cow_intervals, old_intervals);
+            ASSERT_TRUE(intersect.empty()) << "COW uses space of source partitions";
+        }
+    }
+}
+
 }  // namespace snapshot
 }  // namespace android
 
diff --git a/fs_mgr/libsnapshot/snapshotctl.cpp b/fs_mgr/libsnapshot/snapshotctl.cpp
new file mode 100644
index 0000000..d65320c
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshotctl.cpp
@@ -0,0 +1,115 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <sysexits.h>
+
+#include <chrono>
+#include <iostream>
+#include <map>
+
+#include <android-base/logging.h>
+#include <libsnapshot/snapshot.h>
+
+using namespace std::string_literals;
+
+int Usage() {
+    std::cerr << "snapshotctl: Control snapshots.\n"
+                 "Usage: snapshotctl [action] [flags]\n"
+                 "Actions:\n"
+                 "  dump\n"
+                 "    Print snapshot states.\n"
+                 "  merge [--logcat]\n"
+                 "    Initialize merge and wait for it to be completed.\n"
+                 "    If --logcat is specified, log to logcat. Otherwise, log to stdout.\n";
+    return EX_USAGE;
+}
+
+namespace android {
+namespace snapshot {
+
+bool DumpCmdHandler(int /*argc*/, char** argv) {
+    android::base::InitLogging(argv, &android::base::StderrLogger);
+    return SnapshotManager::New()->Dump(std::cout);
+}
+
+bool MergeCmdHandler(int argc, char** argv) {
+    auto begin = std::chrono::steady_clock::now();
+
+    bool log_to_logcat = false;
+    for (int i = 2; i < argc; ++i) {
+        if (argv[i] == "--logcat"s) {
+            log_to_logcat = true;
+        }
+    }
+    if (log_to_logcat) {
+        android::base::InitLogging(argv);
+    } else {
+        android::base::InitLogging(argv, &android::base::StdioLogger);
+    }
+
+    auto sm = SnapshotManager::New();
+
+    auto state = sm->GetUpdateState();
+    if (state == UpdateState::None) {
+        LOG(INFO) << "Can't find any snapshot to merge.";
+        return true;
+    }
+    if (state == UpdateState::Unverified) {
+        if (!sm->InitiateMerge()) {
+            LOG(ERROR) << "Failed to initiate merge.";
+            return false;
+        }
+    }
+
+    // All other states can be handled by ProcessUpdateState.
+    LOG(INFO) << "Waiting for any merge to complete. This can take up to 1 minute.";
+    state = SnapshotManager::New()->ProcessUpdateState();
+
+    if (state == UpdateState::MergeCompleted) {
+        auto end = std::chrono::steady_clock::now();
+        auto passed = std::chrono::duration_cast<std::chrono::milliseconds>(end - begin).count();
+        LOG(INFO) << "Snapshot merged in " << passed << " ms.";
+        return true;
+    }
+
+    LOG(ERROR) << "Snapshot failed to merge with state \"" << state << "\".";
+    return false;
+}
+
+static std::map<std::string, std::function<bool(int, char**)>> kCmdMap = {
+        // clang-format off
+        {"dump", DumpCmdHandler},
+        {"merge", MergeCmdHandler},
+        // clang-format on
+};
+
+}  // namespace snapshot
+}  // namespace android
+
+int main(int argc, char** argv) {
+    using namespace android::snapshot;
+    if (argc < 2) {
+        return Usage();
+    }
+
+    for (const auto& cmd : kCmdMap) {
+        if (cmd.first == argv[1]) {
+            return cmd.second(argc, argv) ? EX_OK : EX_SOFTWARE;
+        }
+    }
+
+    return Usage();
+}
diff --git a/fs_mgr/libsnapshot/snapshotctl.rc b/fs_mgr/libsnapshot/snapshotctl.rc
new file mode 100644
index 0000000..29707f1
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshotctl.rc
@@ -0,0 +1,2 @@
+on property:sys.boot_completed=1
+    exec - root root -- /system/bin/snapshotctl merge --logcat
diff --git a/fs_mgr/libsnapshot/test_helpers.cpp b/fs_mgr/libsnapshot/test_helpers.cpp
index e12ec77..1a6a593 100644
--- a/fs_mgr/libsnapshot/test_helpers.cpp
+++ b/fs_mgr/libsnapshot/test_helpers.cpp
@@ -27,6 +27,8 @@
 using android::base::unique_fd;
 using android::base::WriteFully;
 using android::fiemap::IImageManager;
+using testing::AssertionFailure;
+using testing::AssertionSuccess;
 
 void DeleteBackingImage(IImageManager* manager, const std::string& name) {
     if (manager->IsImageMapped(name)) {
@@ -110,5 +112,40 @@
     return ToHexString(out, sizeof(out));
 }
 
+AssertionResult FillFakeMetadata(MetadataBuilder* builder, const DeltaArchiveManifest& manifest,
+                                 const std::string& suffix) {
+    for (const auto& group : manifest.dynamic_partition_metadata().groups()) {
+        if (!builder->AddGroup(group.name() + suffix, group.size())) {
+            return AssertionFailure()
+                   << "Cannot add group " << group.name() << " with size " << group.size();
+        }
+        for (const auto& partition_name : group.partition_names()) {
+            auto p = builder->AddPartition(partition_name + suffix, group.name() + suffix,
+                                           0 /* attr */);
+            if (!p) {
+                return AssertionFailure() << "Cannot add partition " << partition_name + suffix
+                                          << " to group " << group.name() << suffix;
+            }
+        }
+    }
+    for (const auto& partition : manifest.partitions()) {
+        auto p = builder->FindPartition(partition.partition_name() + suffix);
+        if (!p) {
+            return AssertionFailure() << "Cannot resize partition " << partition.partition_name()
+                                      << suffix << "; it is not found.";
+        }
+        if (!builder->ResizePartition(p, partition.new_partition_info().size())) {
+            return AssertionFailure()
+                   << "Cannot resize partition " << partition.partition_name() << suffix
+                   << " to size " << partition.new_partition_info().size();
+        }
+    }
+    return AssertionSuccess();
+}
+
+void SetSize(PartitionUpdate* partition_update, uint64_t size) {
+    partition_update->mutable_new_partition_info()->set_size(size);
+}
+
 }  // namespace snapshot
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/test_helpers.h b/fs_mgr/libsnapshot/test_helpers.h
index d917e35..bb19adc 100644
--- a/fs_mgr/libsnapshot/test_helpers.h
+++ b/fs_mgr/libsnapshot/test_helpers.h
@@ -17,13 +17,27 @@
 #include <optional>
 #include <string>
 
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
 #include <libfiemap/image_manager.h>
+#include <liblp/mock_property_fetcher.h>
 #include <liblp/partition_opener.h>
 #include <libsnapshot/snapshot.h>
+#include <update_engine/update_metadata.pb.h>
 
 namespace android {
 namespace snapshot {
 
+using android::fs_mgr::IPropertyFetcher;
+using android::fs_mgr::MetadataBuilder;
+using android::fs_mgr::testing::MockPropertyFetcher;
+using chromeos_update_engine::DeltaArchiveManifest;
+using chromeos_update_engine::PartitionUpdate;
+using testing::_;
+using testing::AssertionResult;
+using testing::NiceMock;
+using testing::Return;
+
 using namespace std::string_literals;
 
 // Redirect requests for "super" to our fake super partition.
@@ -45,9 +59,14 @@
   public:
     TestDeviceInfo() {}
     explicit TestDeviceInfo(const std::string& fake_super) { set_fake_super(fake_super); }
+    TestDeviceInfo(const std::string& fake_super, const std::string& slot_suffix)
+        : TestDeviceInfo(fake_super) {
+        set_slot_suffix(slot_suffix);
+    }
     std::string GetGsidDir() const override { return "ota/test"s; }
     std::string GetMetadataDir() const override { return "/metadata/ota/test"s; }
     std::string GetSlotSuffix() const override { return slot_suffix_; }
+    std::string GetOtherSlotSuffix() const override { return slot_suffix_ == "_a" ? "_b" : "_a"; }
     std::string GetSuperDevice([[maybe_unused]] uint32_t slot) const override { return "super"; }
     const android::fs_mgr::IPartitionOpener& GetPartitionOpener() const override {
         return *opener_.get();
@@ -64,6 +83,28 @@
     std::unique_ptr<TestPartitionOpener> opener_;
 };
 
+class SnapshotTestPropertyFetcher : public android::fs_mgr::testing::MockPropertyFetcher {
+  public:
+    SnapshotTestPropertyFetcher(const std::string& slot_suffix) {
+        ON_CALL(*this, GetProperty("ro.boot.slot_suffix", _)).WillByDefault(Return(slot_suffix));
+        ON_CALL(*this, GetBoolProperty("ro.boot.dynamic_partitions", _))
+                .WillByDefault(Return(true));
+        ON_CALL(*this, GetBoolProperty("ro.boot.dynamic_partitions_retrofit", _))
+                .WillByDefault(Return(false));
+        ON_CALL(*this, GetBoolProperty("ro.virtual_ab.enabled", _)).WillByDefault(Return(true));
+    }
+
+    static void SetUp(const std::string& slot_suffix = "_a") { Reset(slot_suffix); }
+
+    static void TearDown() { Reset("_a"); }
+
+  private:
+    static void Reset(const std::string& slot_suffix) {
+        IPropertyFetcher::OverrideForTesting(
+                std::make_unique<NiceMock<SnapshotTestPropertyFetcher>>(slot_suffix));
+    }
+};
+
 // Helper for error-spam-free cleanup.
 void DeleteBackingImage(android::fiemap::IImageManager* manager, const std::string& name);
 
@@ -72,5 +113,12 @@
 
 std::optional<std::string> GetHash(const std::string& path);
 
+// Add partitions and groups described by |manifest|.
+AssertionResult FillFakeMetadata(MetadataBuilder* builder, const DeltaArchiveManifest& manifest,
+                                 const std::string& suffix);
+
+// In the update package metadata, set a partition with the given size.
+void SetSize(PartitionUpdate* partition_update, uint64_t size);
+
 }  // namespace snapshot
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/utility.h b/fs_mgr/libsnapshot/utility.h
index a700c46..75c694c 100644
--- a/fs_mgr/libsnapshot/utility.h
+++ b/fs_mgr/libsnapshot/utility.h
@@ -22,6 +22,7 @@
 #include <libfiemap/image_manager.h>
 #include <liblp/builder.h>
 #include <libsnapshot/snapshot.h>
+#include <update_engine/update_metadata.pb.h>
 
 namespace android {
 namespace snapshot {
diff --git a/fs_mgr/libvbmeta/Android.bp b/fs_mgr/libvbmeta/Android.bp
new file mode 100644
index 0000000..937e0f3
--- /dev/null
+++ b/fs_mgr/libvbmeta/Android.bp
@@ -0,0 +1,52 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+libvbmeta_lib_deps = [
+    "libbase",
+    "libcrypto",
+]
+
+cc_library {
+    name: "libvbmeta",
+    host_supported: true,
+    srcs: [
+        "builder.cpp",
+        "reader.cpp",
+        "utility.cpp",
+        "writer.cpp",
+    ],
+    shared_libs: [
+        "liblog",
+    ] + libvbmeta_lib_deps,
+    export_include_dirs: ["include"],
+}
+
+cc_test_host {
+    name: "libvbmeta_test",
+    static_libs: [
+        "libsparse",
+        "libvbmeta",
+        "libz",
+    ] + libvbmeta_lib_deps,
+    srcs: [
+        "builder_test.cpp",
+        "super_vbmeta_test.cpp",
+    ],
+    required: [
+        "avbtool",
+        "vbmake",
+    ],
+}
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/builder.cpp b/fs_mgr/libvbmeta/builder.cpp
new file mode 100644
index 0000000..a901a4f
--- /dev/null
+++ b/fs_mgr/libvbmeta/builder.cpp
@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "builder.h"
+
+#include <android-base/file.h>
+#include <openssl/sha.h>
+
+#include "reader.h"
+#include "utility.h"
+#include "writer.h"
+
+using android::base::ErrnoError;
+using android::base::Error;
+using android::base::Result;
+using android::base::unique_fd;
+
+namespace android {
+namespace fs_mgr {
+
+SuperVBMetaBuilder::SuperVBMetaBuilder() {}
+
+SuperVBMetaBuilder::SuperVBMetaBuilder(const int super_vbmeta_fd,
+                                       const std::map<std::string, std::string>& images_path)
+    : super_vbmeta_fd_(super_vbmeta_fd), images_path_(images_path) {}
+
+Result<void> SuperVBMetaBuilder::Build() {
+    for (const auto& [vbmeta_name, file_path] : images_path_) {
+        Result<std::string> content = ReadVBMetaImageFromFile(file_path);
+        if (!content) {
+            return content.error();
+        }
+
+        Result<uint8_t> vbmeta_index = AddVBMetaImage(vbmeta_name);
+        if (!vbmeta_index) {
+            return vbmeta_index.error();
+        }
+
+        Result<void> rv_export_vbmeta_image =
+                ExportVBMetaImageToFile(vbmeta_index.value(), content.value());
+        if (!rv_export_vbmeta_image) {
+            return rv_export_vbmeta_image;
+        }
+    }
+    return {};
+}
+
+Result<std::string> SuperVBMetaBuilder::ReadVBMetaImageFromFile(const std::string& file) {
+    unique_fd source_fd(TEMP_FAILURE_RETRY(open(file.c_str(), O_RDONLY | O_CLOEXEC)));
+    if (source_fd < 0) {
+        return ErrnoError() << "Couldn't open vbmeta image file " << file;
+    }
+
+    Result<uint64_t> file_size = GetFileSize(source_fd);
+    if (!file_size) {
+        return file_size.error();
+    }
+
+    if (file_size.value() > VBMETA_IMAGE_MAX_SIZE) {
+        return Error() << "vbmeta image file size " << file_size.value() << " is too large";
+    }
+
+    std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(VBMETA_IMAGE_MAX_SIZE);
+    if (!android::base::ReadFully(source_fd, buffer.get(), file_size.value())) {
+        return ErrnoError() << "Couldn't read vbmeta image file " << file;
+    }
+
+    return std::string(reinterpret_cast<const char*>(buffer.get()), VBMETA_IMAGE_MAX_SIZE);
+}
+
+Result<uint8_t> SuperVBMetaBuilder::GetEmptySlot() {
+    for (uint8_t i = 0; i < VBMETA_IMAGE_MAX_NUM; ++i) {
+        if ((table_.header.in_use & (1 << i)) == 0) return i;
+    }
+    return Error() << "There isn't empty slot in super vbmeta";
+}
+
+Result<uint8_t> SuperVBMetaBuilder::AddVBMetaImage(const std::string& vbmeta_name) {
+    auto desc = std::find_if(
+            table_.descriptors.begin(), table_.descriptors.end(),
+            [&vbmeta_name](const auto& entry) { return entry.vbmeta_name == vbmeta_name; });
+
+    uint8_t slot_number = 0;
+    if (desc != table_.descriptors.end()) {
+        slot_number = desc->vbmeta_index;
+    } else {
+        Result<uint8_t> new_slot = GetEmptySlot();
+        if (!new_slot) {
+            return new_slot;
+        }
+        slot_number = new_slot.value();
+
+        // insert new descriptor into table
+        InternalVBMetaDescriptor new_desc;
+        new_desc.vbmeta_index = slot_number;
+        new_desc.vbmeta_name_length = vbmeta_name.length();
+        new_desc.vbmeta_name = vbmeta_name;
+        memset(new_desc.reserved, 0, sizeof(new_desc.reserved));
+        table_.descriptors.emplace_back(std::move(new_desc));
+
+        // mark slot as in use
+        table_.header.in_use |= (1 << slot_number);
+    }
+
+    return slot_number;
+}
+
+void SuperVBMetaBuilder::DeleteVBMetaImage(const std::string& vbmeta_name) {
+    auto desc = std::find_if(
+            table_.descriptors.begin(), table_.descriptors.end(),
+            [&vbmeta_name](const auto& entry) { return entry.vbmeta_name == vbmeta_name; });
+
+    if (desc != table_.descriptors.end()) {
+        // mark slot as not in use
+        table_.header.in_use &= ~(1 << desc->vbmeta_index);
+
+        // erase descriptor in table
+        table_.descriptors.erase(desc);
+    }
+}
+
+std::unique_ptr<VBMetaTable> SuperVBMetaBuilder::ExportVBMetaTable() {
+    // calculate descriptors size
+    uint32_t descriptors_size = 0;
+    for (const auto& desc : table_.descriptors) {
+        descriptors_size += SUPER_VBMETA_DESCRIPTOR_SIZE + desc.vbmeta_name_length * sizeof(char);
+    }
+
+    // export header
+    table_.header.magic = SUPER_VBMETA_MAGIC;
+    table_.header.major_version = SUPER_VBMETA_MAJOR_VERSION;
+    table_.header.minor_version = SUPER_VBMETA_MINOR_VERSION;
+    table_.header.header_size = SUPER_VBMETA_HEADER_SIZE;
+    table_.header.total_size = SUPER_VBMETA_HEADER_SIZE + descriptors_size;
+    memset(table_.header.checksum, 0, sizeof(table_.header.checksum));
+    table_.header.descriptors_size = descriptors_size;
+    memset(table_.header.reserved, 0, sizeof(table_.header.reserved));
+    std::string serialized_table = SerializeVBMetaTable(table_);
+    ::SHA256(reinterpret_cast<const uint8_t*>(serialized_table.c_str()), table_.header.total_size,
+             &table_.header.checksum[0]);
+
+    return std::make_unique<VBMetaTable>(table_);
+}
+
+Result<void> SuperVBMetaBuilder::ExportVBMetaTableToFile() {
+    std::unique_ptr<VBMetaTable> table = ExportVBMetaTable();
+
+    std::string serialized_table = SerializeVBMetaTable(*table);
+
+    android::base::Result<void> rv_write_primary_vbmeta_table =
+            WritePrimaryVBMetaTable(super_vbmeta_fd_, serialized_table);
+    if (!rv_write_primary_vbmeta_table) {
+        return rv_write_primary_vbmeta_table;
+    }
+
+    android::base::Result<void> rv_write_backup_vbmeta_table =
+            WriteBackupVBMetaTable(super_vbmeta_fd_, serialized_table);
+    return rv_write_backup_vbmeta_table;
+}
+
+Result<void> SuperVBMetaBuilder::ExportVBMetaImageToFile(const uint8_t vbmeta_index,
+                                                         const std::string& vbmeta_image) {
+    Result<void> rv_write_vbmeta_image =
+            WriteVBMetaImage(super_vbmeta_fd_, vbmeta_index, vbmeta_image);
+    if (!rv_write_vbmeta_image) {
+        return rv_write_vbmeta_image;
+    }
+
+    Result<void> rv_validate_vbmeta_image =
+            ValidateVBMetaImage(super_vbmeta_fd_, vbmeta_index, vbmeta_image);
+    return rv_validate_vbmeta_image;
+}
+
+bool WriteToSuperVBMetaFile(const std::string& super_vbmeta_file,
+                            const std::map<std::string, std::string>& images_path) {
+    unique_fd super_vbmeta_fd(TEMP_FAILURE_RETRY(
+            open(super_vbmeta_file.c_str(), O_CREAT | O_RDWR | O_TRUNC | O_CLOEXEC, 0644)));
+    if (super_vbmeta_fd < 0) {
+        PERROR << "Couldn't open super vbmeta file " << super_vbmeta_file;
+        return false;
+    }
+
+    SuperVBMetaBuilder builder(super_vbmeta_fd, images_path);
+
+    Result<void> rv_build = builder.Build();
+    if (!rv_build) {
+        LERROR << rv_build.error();
+        return false;
+    }
+
+    Result<void> rv_export = builder.ExportVBMetaTableToFile();
+    if (!rv_export) {
+        LERROR << rv_export.error();
+        return false;
+    }
+
+    return true;
+}
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/builder.h b/fs_mgr/libvbmeta/builder.h
new file mode 100644
index 0000000..58ea36a
--- /dev/null
+++ b/fs_mgr/libvbmeta/builder.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <map>
+#include <string>
+
+#include <android-base/result.h>
+
+#include "super_vbmeta_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+class SuperVBMetaBuilder {
+  public:
+    SuperVBMetaBuilder();
+    SuperVBMetaBuilder(const int super_vbmeta_fd,
+                       const std::map<std::string, std::string>& images_path);
+    android::base::Result<void> Build();
+    android::base::Result<std::string> ReadVBMetaImageFromFile(const std::string& file);
+    // It adds the vbmeta image in super_vbmeta and returns the index
+    // (which has the same meaning with vbmeta_index of VBMetaDescriptor).
+    android::base::Result<uint8_t> AddVBMetaImage(const std::string& vbmeta_name);
+    void DeleteVBMetaImage(const std::string& vbmeta_name);
+    std::unique_ptr<VBMetaTable> ExportVBMetaTable();
+    android::base::Result<void> ExportVBMetaTableToFile();
+    android::base::Result<void> ExportVBMetaImageToFile(const uint8_t vbmeta_index,
+                                                        const std::string& vbmeta_image);
+
+  private:
+    android::base::Result<uint8_t> GetEmptySlot();
+
+    int super_vbmeta_fd_;
+    VBMetaTable table_;
+    // Maps vbmeta image name to vbmeta image file path.
+    std::map<std::string, std::string> images_path_;
+};
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/builder_test.cpp b/fs_mgr/libvbmeta/builder_test.cpp
new file mode 100644
index 0000000..9a015fd
--- /dev/null
+++ b/fs_mgr/libvbmeta/builder_test.cpp
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "builder.h"
+#include "super_vbmeta_format.h"
+
+using android::base::Result;
+using android::fs_mgr::SuperVBMetaBuilder;
+
+TEST(BuilderTest, VBMetaTableBasic) {
+    std::unique_ptr<SuperVBMetaBuilder> builder = std::make_unique<SuperVBMetaBuilder>();
+    ASSERT_NE(builder, nullptr);
+
+    Result<uint8_t> vbmeta_index = builder->AddVBMetaImage("vbmeta" /* vbmeta_name */
+    );
+    EXPECT_TRUE(vbmeta_index);
+
+    Result<uint8_t> vbmeta_system_slot = builder->AddVBMetaImage("vbmeta_system" /* vbmeta_name */
+    );
+    EXPECT_TRUE(vbmeta_system_slot);
+
+    Result<uint8_t> vbmeta_vendor_slot = builder->AddVBMetaImage("vbmeta_vendor" /* vbmeta_name */
+    );
+    EXPECT_TRUE(vbmeta_vendor_slot);
+
+    builder->DeleteVBMetaImage("vbmeta_system" /* vbmeta_name */
+    );
+
+    Result<uint8_t> vbmeta_product_slot = builder->AddVBMetaImage("vbmeta_product" /* vbmeta_name */
+    );
+    EXPECT_TRUE(vbmeta_product_slot);
+
+    std::unique_ptr<VBMetaTable> table = builder->ExportVBMetaTable();
+    ASSERT_NE(table, nullptr);
+
+    // check for vbmeta table header
+    EXPECT_EQ(table->header.magic, SUPER_VBMETA_MAGIC);
+    EXPECT_EQ(table->header.major_version, SUPER_VBMETA_MAJOR_VERSION);
+    EXPECT_EQ(table->header.minor_version, SUPER_VBMETA_MINOR_VERSION);
+    EXPECT_EQ(table->header.header_size, SUPER_VBMETA_HEADER_SIZE);
+    EXPECT_EQ(table->header.total_size,
+              SUPER_VBMETA_HEADER_SIZE + SUPER_VBMETA_DESCRIPTOR_SIZE * 3 + 33);
+    EXPECT_EQ(table->header.descriptors_size, SUPER_VBMETA_DESCRIPTOR_SIZE * 3 + 33);
+
+    // Test for vbmeta table descriptors
+    EXPECT_EQ(table->descriptors.size(), 3);
+
+    EXPECT_EQ(table->descriptors[0].vbmeta_index, 0);
+    EXPECT_EQ(table->descriptors[0].vbmeta_name_length, 6);
+    for (int i = 0; i < sizeof(table->descriptors[0].reserved); i++)
+        EXPECT_EQ(table->descriptors[0].reserved[i], 0);
+    EXPECT_EQ(table->descriptors[0].vbmeta_name, "vbmeta");
+
+    EXPECT_EQ(table->descriptors[1].vbmeta_index, 2);
+    EXPECT_EQ(table->descriptors[1].vbmeta_name_length, 13);
+    for (int i = 0; i < sizeof(table->descriptors[1].reserved); i++)
+        EXPECT_EQ(table->descriptors[1].reserved[i], 0);
+    EXPECT_EQ(table->descriptors[1].vbmeta_name, "vbmeta_vendor");
+
+    EXPECT_EQ(table->descriptors[2].vbmeta_index, 1);
+    EXPECT_EQ(table->descriptors[2].vbmeta_name_length, 14);
+    for (int i = 0; i < sizeof(table->descriptors[2].reserved); i++)
+        EXPECT_EQ(table->descriptors[2].reserved[i], 0);
+    EXPECT_EQ(table->descriptors[2].vbmeta_name, "vbmeta_product");
+}
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/include/libvbmeta/libvbmeta.h b/fs_mgr/libvbmeta/include/libvbmeta/libvbmeta.h
new file mode 100644
index 0000000..ab7ba73
--- /dev/null
+++ b/fs_mgr/libvbmeta/include/libvbmeta/libvbmeta.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <map>
+#include <string>
+
+namespace android {
+namespace fs_mgr {
+
+bool WriteToSuperVBMetaFile(const std::string& super_vbmeta_file,
+                            const std::map<std::string, std::string>& images_path);
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/reader.cpp b/fs_mgr/libvbmeta/reader.cpp
new file mode 100644
index 0000000..212d186
--- /dev/null
+++ b/fs_mgr/libvbmeta/reader.cpp
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "reader.h"
+
+#include <android-base/file.h>
+
+using android::base::ErrnoError;
+using android::base::Error;
+using android::base::Result;
+
+namespace android {
+namespace fs_mgr {
+
+Result<void> LoadAndVerifySuperVBMetaHeader(const void* buffer, SuperVBMetaHeader* header) {
+    memcpy(header, buffer, sizeof(*header));
+
+    // Do basic validation of super vbmeta.
+    if (header->magic != SUPER_VBMETA_MAGIC) {
+        return Error() << "Super VBMeta has invalid magic value";
+    }
+
+    // Check that the version is compatible.
+    if (header->major_version != SUPER_VBMETA_MAJOR_VERSION ||
+        header->minor_version > SUPER_VBMETA_MINOR_VERSION) {
+        return Error() << "Super VBMeta has incompatible version";
+    }
+    return {};
+}
+
+void LoadVBMetaDescriptors(const void* buffer, uint32_t size,
+                           std::vector<InternalVBMetaDescriptor>* descriptors) {
+    for (int p = 0; p < size;) {
+        InternalVBMetaDescriptor descriptor;
+        memcpy(&descriptor, (char*)buffer + p, SUPER_VBMETA_DESCRIPTOR_SIZE);
+        p += SUPER_VBMETA_DESCRIPTOR_SIZE;
+
+        descriptor.vbmeta_name = std::string((char*)buffer + p, descriptor.vbmeta_name_length);
+        p += descriptor.vbmeta_name_length;
+
+        descriptors->emplace_back(std::move(descriptor));
+    }
+}
+
+Result<void> ReadVBMetaTable(int fd, uint64_t offset, VBMetaTable* table) {
+    std::unique_ptr<uint8_t[]> header_buffer =
+            std::make_unique<uint8_t[]>(SUPER_VBMETA_HEADER_SIZE);
+    if (!android::base::ReadFullyAtOffset(fd, header_buffer.get(), SUPER_VBMETA_HEADER_SIZE,
+                                          offset)) {
+        return ErrnoError() << "Couldn't read super vbmeta header at offset " << offset;
+    }
+
+    Result<void> rv_header = LoadAndVerifySuperVBMetaHeader(header_buffer.get(), &table->header);
+    if (!rv_header) {
+        return rv_header;
+    }
+
+    const uint64_t descriptors_offset = offset + table->header.header_size;
+    std::unique_ptr<uint8_t[]> descriptors_buffer =
+            std::make_unique<uint8_t[]>(table->header.descriptors_size);
+    if (!android::base::ReadFullyAtOffset(fd, descriptors_buffer.get(),
+                                          table->header.descriptors_size, descriptors_offset)) {
+        return ErrnoError() << "Couldn't read super vbmeta descriptors at offset "
+                            << descriptors_offset;
+    }
+
+    LoadVBMetaDescriptors(descriptors_buffer.get(), table->header.descriptors_size,
+                          &table->descriptors);
+    return {};
+}
+
+Result<void> ReadPrimaryVBMetaTable(int fd, VBMetaTable* table) {
+    uint64_t offset = PRIMARY_SUPER_VBMETA_TABLE_OFFSET;
+    return ReadVBMetaTable(fd, offset, table);
+}
+
+Result<void> ReadBackupVBMetaTable(int fd, VBMetaTable* table) {
+    uint64_t offset = BACKUP_SUPER_VBMETA_TABLE_OFFSET;
+    return ReadVBMetaTable(fd, offset, table);
+}
+
+Result<std::string> ReadVBMetaImage(int fd, int slot) {
+    const uint64_t offset = 2 * SUPER_VBMETA_TABLE_MAX_SIZE + slot * VBMETA_IMAGE_MAX_SIZE;
+    std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(VBMETA_IMAGE_MAX_SIZE);
+    if (!android::base::ReadFullyAtOffset(fd, buffer.get(), VBMETA_IMAGE_MAX_SIZE, offset)) {
+        return ErrnoError() << "Couldn't read vbmeta image at offset " << offset;
+    }
+    return std::string(reinterpret_cast<char*>(buffer.get()), VBMETA_IMAGE_MAX_SIZE);
+}
+
+Result<void> ValidateVBMetaImage(int super_vbmeta_fd, int vbmeta_index,
+                                 const std::string& vbmeta_image) {
+    Result<std::string> content = ReadVBMetaImage(super_vbmeta_fd, vbmeta_index);
+    if (!content) {
+        return content.error();
+    }
+
+    if (vbmeta_image != content.value()) {
+        return Error() << "VBMeta Image in Super VBMeta differ from the original one.";
+    }
+    return {};
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/libvbmeta/reader.h b/fs_mgr/libvbmeta/reader.h
new file mode 100644
index 0000000..f0997ff
--- /dev/null
+++ b/fs_mgr/libvbmeta/reader.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <android-base/result.h>
+
+#include "super_vbmeta_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+android::base::Result<void> ReadPrimaryVBMetaTable(int fd, VBMetaTable* table);
+android::base::Result<void> ReadBackupVBMetaTable(int fd, VBMetaTable* table);
+android::base::Result<std::string> ReadVBMetaImage(int fd, int slot);
+
+android::base::Result<void> ValidateVBMetaImage(int super_vbmeta_fd, int vbmeta_index,
+                                                const std::string& vbmeta_image);
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/super_vbmeta_format.h b/fs_mgr/libvbmeta/super_vbmeta_format.h
new file mode 100644
index 0000000..c62a2dd
--- /dev/null
+++ b/fs_mgr/libvbmeta/super_vbmeta_format.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* This .h file is intended for CPP clients (usually fastbootd, recovery and update_engine)  */
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "super_vbmeta_format_c.h"
+
+struct InternalVBMetaDescriptor : VBMetaDescriptor {
+    /*  64: The vbmeta image's name */
+    std::string vbmeta_name;
+};
+
+struct VBMetaTable {
+    SuperVBMetaHeader header;
+    std::vector<InternalVBMetaDescriptor> descriptors;
+};
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/super_vbmeta_format_c.h b/fs_mgr/libvbmeta/super_vbmeta_format_c.h
new file mode 100644
index 0000000..6d79801
--- /dev/null
+++ b/fs_mgr/libvbmeta/super_vbmeta_format_c.h
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* This .h file is intended for C clients (usually bootloader).  */
+
+#pragma once
+
+#include <stdint.h>
+
+/* Magic signature for super vbmeta. */
+#define SUPER_VBMETA_MAGIC 0x5356424d
+
+/* Current super vbmeta version. */
+#define SUPER_VBMETA_MAJOR_VERSION 1
+#define SUPER_VBMETA_MINOR_VERSION 0
+
+/* super vbmeta size. */
+#define SUPER_VBMETA_HEADER_SIZE sizeof(SuperVBMetaHeader)
+#define SUPER_VBMETA_DESCRIPTOR_SIZE sizeof(VBMetaDescriptor)
+#define SUPER_VBMETA_TABLE_MAX_SIZE 2048
+
+/* super vbmeta offset. */
+#define PRIMARY_SUPER_VBMETA_TABLE_OFFSET 0
+#define BACKUP_SUPER_VBMETA_TABLE_OFFSET SUPER_VBMETA_TABLE_MAX_SIZE
+
+/* restriction of vbmeta image */
+#define VBMETA_IMAGE_MAX_NUM 32
+#define VBMETA_IMAGE_MAX_SIZE 64 * 1024
+
+/* Binary format of the super vbmeta image.
+ *
+ * The super vbmeta image consists of two blocks:
+ *
+ *  +------------------------------------------+
+ *  | Super VBMeta Table - fixed size          |
+ *  +------------------------------------------+
+ *  | Backup Super VBMeta Table - fixed size   |
+ *  +------------------------------------------+
+ *  | VBMeta Images - fixed size               |
+ *  +------------------------------------------+
+ *
+ *  The "Super VBMeta Table" records the offset
+ *  and the size of each vbmeta_partition within
+ *  /super_vbmeta.
+ *
+ *  The "VBMeta Image" is copied from each vbmeta_partition
+ *  and filled with 0 until 64K bytes.
+ *
+ * The super vbmeta table consists of two blocks:
+ *
+ *  +-----------------------------------------+
+ *  | Header data - fixed size                |
+ *  +-----------------------------------------+
+ *  | VBMeta descriptors - variable size      |
+ *  +-----------------------------------------+
+ *
+ * The "Header data" block is described by the following struct and
+ * is always 128 bytes long.
+ *
+ * The "VBMeta descriptor" is |descriptors_size| + |vbmeta_name_length|
+ * bytes long. It contains the offset and size for each vbmeta image
+ * and is followed by |vbmeta_name_length| bytes of the partition name
+ * (UTF-8 encoded).
+ */
+
+typedef struct SuperVBMetaHeader {
+    /*  0: Magic signature (SUPER_VBMETA_MAGIC). */
+    uint32_t magic;
+
+    /*  4: Major version. Version number required to read this super vbmeta. If the version is not
+     * equal to the library version, the super vbmeta should be considered incompatible.
+     */
+    uint16_t major_version;
+
+    /*  6: Minor version. A library supporting newer features should be able to
+     * read super vbmeta with an older minor version. However, an older library
+     * should not support reading super vbmeta if its minor version is higher.
+     */
+    uint16_t minor_version;
+
+    /*  8: The size of this header struct. */
+    uint32_t header_size;
+
+    /*  12: The size of this super vbmeta table. */
+    uint32_t total_size;
+
+    /*  16: SHA256 checksum of this super vbmeta table, with this field set to 0. */
+    uint8_t checksum[32];
+
+    /*  48: The size of the vbmeta table descriptors. */
+    uint32_t descriptors_size;
+
+    /*  52: mark which slot is in use. */
+    uint32_t in_use = 0;
+
+    /*  56: reserved for other usage, filled with 0. */
+    uint8_t reserved[72];
+} __attribute__((packed)) SuperVBMetaHeader;
+
+typedef struct VBMetaDescriptor {
+    /*  0: The slot number of the vbmeta image. */
+    uint8_t vbmeta_index;
+
+    /*  12: The length of the vbmeta image name. */
+    uint32_t vbmeta_name_length;
+
+    /*  16: Space reserved for other usage, filled with 0. */
+    uint8_t reserved[48];
+} __attribute__((packed)) VBMetaDescriptor;
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/super_vbmeta_test.cpp b/fs_mgr/libvbmeta/super_vbmeta_test.cpp
new file mode 100644
index 0000000..6b4fc5d
--- /dev/null
+++ b/fs_mgr/libvbmeta/super_vbmeta_test.cpp
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <android-base/file.h>
+#include <gtest/gtest.h>
+#include <openssl/sha.h>
+#include <sparse/sparse.h>
+
+#include "reader.h"
+#include "super_vbmeta_format.h"
+#include "utility.h"
+#include "writer.h"
+
+#define FAKE_DATA_SIZE 40960
+#define FAKE_PARTITION_SIZE FAKE_DATA_SIZE * 25
+
+using android::base::Result;
+using android::fs_mgr::GetFileSize;
+using android::fs_mgr::ReadVBMetaImage;
+using SparsePtr = std::unique_ptr<sparse_file, decltype(&sparse_file_destroy)>;
+
+void GeneratePartitionImage(int fd, const std::string& file_name,
+                            const std::string& partition_name) {
+    std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(FAKE_DATA_SIZE);
+    for (size_t c = 0; c < FAKE_DATA_SIZE; c++) {
+        buffer[c] = uint8_t(c);
+    }
+
+    SparsePtr file(sparse_file_new(512 /* block size */, FAKE_DATA_SIZE), sparse_file_destroy);
+    EXPECT_TRUE(file);
+    EXPECT_EQ(0, sparse_file_add_data(file.get(), buffer.get(), FAKE_DATA_SIZE,
+                                      0 /* offset in blocks */));
+    EXPECT_EQ(0, sparse_file_write(file.get(), fd, false /* gz */, true /* sparse */,
+                                   false /* crc */));
+
+    std::stringstream cmd;
+    cmd << "avbtool add_hashtree_footer"
+        << " --image " << file_name << " --partition_name " << partition_name
+        << " --partition_size " << FAKE_PARTITION_SIZE << " --algorithm SHA256_RSA2048"
+        << " --key external/avb/test/data/testkey_rsa2048.pem";
+
+    int rc = system(cmd.str().c_str());
+    EXPECT_TRUE(WIFEXITED(rc));
+    EXPECT_EQ(WEXITSTATUS(rc), 0);
+}
+
+void GenerateVBMetaImage(const std::string& vbmeta_file_name,
+                         const std::string& include_file_name) {
+    std::stringstream cmd;
+    cmd << "avbtool make_vbmeta_image"
+        << " --output " << vbmeta_file_name << " --include_descriptors_from_image "
+        << include_file_name;
+
+    int rc = system(cmd.str().c_str());
+    EXPECT_TRUE(WIFEXITED(rc));
+    EXPECT_EQ(WEXITSTATUS(rc), 0);
+}
+
+std::string ReadVBMetaImageFromFile(const std::string& file) {
+    android::base::unique_fd fd(open(file.c_str(), O_RDONLY | O_CLOEXEC));
+    EXPECT_GT(fd, 0);
+    Result<uint64_t> file_size = GetFileSize(fd);
+    EXPECT_TRUE(file_size);
+    std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(VBMETA_IMAGE_MAX_SIZE);
+    EXPECT_TRUE(android::base::ReadFully(fd, buffer.get(), file_size.value()));
+    return std::string(reinterpret_cast<char*>(buffer.get()), VBMETA_IMAGE_MAX_SIZE);
+}
+
+TEST(VBMetaTableTest, VBMetaTableBasic) {
+    TemporaryDir td;
+
+    // Generate Partition Image
+    TemporaryFile system_tf(std::string(td.path));
+    std::string system_path(system_tf.path);
+    GeneratePartitionImage(system_tf.fd, system_path, "system");
+    system_tf.release();
+
+    TemporaryFile vendor_tf(std::string(td.path));
+    std::string vendor_path(vendor_tf.path);
+    GeneratePartitionImage(vendor_tf.fd, vendor_path, "vendor");
+    vendor_tf.release();
+
+    TemporaryFile product_tf(std::string(td.path));
+    std::string product_path(product_tf.path);
+    GeneratePartitionImage(product_tf.fd, product_path, "product");
+    product_tf.release();
+
+    // Generate VBMeta Image
+    std::string vbmeta_system_path(td.path);
+    vbmeta_system_path.append("/vbmeta_system.img");
+    GenerateVBMetaImage(vbmeta_system_path, system_path);
+
+    std::string vbmeta_vendor_path(td.path);
+    vbmeta_vendor_path.append("/vbmeta_vendor.img");
+    GenerateVBMetaImage(vbmeta_vendor_path, vendor_path);
+
+    std::string vbmeta_product_path(td.path);
+    vbmeta_product_path.append("/vbmeta_product.img");
+    GenerateVBMetaImage(vbmeta_product_path, product_path);
+
+    // Generate Super VBMeta Image
+    std::string super_vbmeta_path(td.path);
+    super_vbmeta_path.append("/super_vbmeta.img");
+
+    std::stringstream cmd;
+    cmd << "vbmake"
+        << " --image "
+        << "vbmeta_system"
+        << "=" << vbmeta_system_path << " --image "
+        << "vbmeta_vendor"
+        << "=" << vbmeta_vendor_path << " --image "
+        << "vbmeta_product"
+        << "=" << vbmeta_product_path << " --output=" << super_vbmeta_path;
+
+    int rc = system(cmd.str().c_str());
+    ASSERT_TRUE(WIFEXITED(rc));
+    ASSERT_EQ(WEXITSTATUS(rc), 0);
+
+    android::base::unique_fd fd(open(super_vbmeta_path.c_str(), O_RDONLY | O_CLOEXEC));
+    EXPECT_GT(fd, 0);
+
+    // Check the size of vbmeta table
+    Result<uint64_t> super_vbmeta_size = GetFileSize(fd);
+    EXPECT_TRUE(super_vbmeta_size);
+    EXPECT_EQ(super_vbmeta_size.value(),
+              SUPER_VBMETA_TABLE_MAX_SIZE * 2 + VBMETA_IMAGE_MAX_SIZE * 3);
+
+    // Check Primary vbmeta table is equal to Backup one
+    VBMetaTable table;
+    EXPECT_TRUE(android::fs_mgr::ReadPrimaryVBMetaTable(fd, &table));
+    VBMetaTable table_backup;
+    EXPECT_TRUE(android::fs_mgr::ReadBackupVBMetaTable(fd, &table_backup));
+    EXPECT_EQ(android::fs_mgr::SerializeVBMetaTable(table),
+              android::fs_mgr::SerializeVBMetaTable(table_backup));
+
+    // Check vbmeta table Header Checksum
+    std::string serial_table = android::fs_mgr::SerializeVBMetaTable(table);
+    std::string serial_removed_checksum(serial_table);
+    // Replace checksum 32 bytes (starts at 16th byte) with 0
+    serial_removed_checksum.replace(16, 32, 32, 0);
+    uint8_t test_checksum[32];
+    ::SHA256(reinterpret_cast<const uint8_t*>(serial_removed_checksum.c_str()),
+             table.header.total_size, &test_checksum[0]);
+    EXPECT_EQ(memcmp(table.header.checksum, test_checksum, 32), 0);
+
+    // Check vbmeta table descriptors and vbmeta images
+    EXPECT_EQ(table.descriptors.size(), 3);
+
+    EXPECT_EQ(table.descriptors[0].vbmeta_index, 0);
+    EXPECT_EQ(table.descriptors[0].vbmeta_name_length, 14);
+    EXPECT_EQ(table.descriptors[0].vbmeta_name, "vbmeta_product");
+    Result<std::string> vbmeta_product_content = ReadVBMetaImage(fd, 0);
+    EXPECT_TRUE(vbmeta_product_content);
+    EXPECT_EQ(ReadVBMetaImageFromFile(vbmeta_product_path), vbmeta_product_content.value());
+
+    EXPECT_EQ(table.descriptors[1].vbmeta_index, 1);
+    EXPECT_EQ(table.descriptors[1].vbmeta_name_length, 13);
+    EXPECT_EQ(table.descriptors[1].vbmeta_name, "vbmeta_system");
+    Result<std::string> vbmeta_system_content = ReadVBMetaImage(fd, 1);
+    EXPECT_TRUE(vbmeta_system_content);
+    EXPECT_EQ(ReadVBMetaImageFromFile(vbmeta_system_path), vbmeta_system_content.value());
+
+    EXPECT_EQ(table.descriptors[2].vbmeta_index, 2);
+    EXPECT_EQ(table.descriptors[2].vbmeta_name_length, 13);
+    EXPECT_EQ(table.descriptors[2].vbmeta_name, "vbmeta_vendor");
+    Result<std::string> vbmeta_vendor_content = ReadVBMetaImage(fd, 2);
+    EXPECT_TRUE(vbmeta_vendor_content);
+    EXPECT_EQ(ReadVBMetaImageFromFile(vbmeta_vendor_path), vbmeta_vendor_content.value());
+}
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/utility.cpp b/fs_mgr/libvbmeta/utility.cpp
new file mode 100644
index 0000000..c184227
--- /dev/null
+++ b/fs_mgr/libvbmeta/utility.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "utility.h"
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "super_vbmeta_format.h"
+
+using android::base::ErrnoError;
+using android::base::Error;
+using android::base::Result;
+
+namespace android {
+namespace fs_mgr {
+
+Result<uint64_t> GetFileSize(int fd) {
+    struct stat sb;
+    if (fstat(fd, &sb) == -1) {
+        return ErrnoError() << "Couldn't get the file size";
+    }
+    return sb.st_size;
+}
+
+uint64_t IndexOffset(const uint8_t vbmeta_index) {
+    /* There are primary and backup vbmeta table in super_vbmeta,
+       so SUPER_VBMETA_TABLE_MAX_SIZE is counted twice. */
+    return 2 * SUPER_VBMETA_TABLE_MAX_SIZE + vbmeta_index * VBMETA_IMAGE_MAX_SIZE;
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/libvbmeta/utility.h b/fs_mgr/libvbmeta/utility.h
new file mode 100644
index 0000000..91db0ad
--- /dev/null
+++ b/fs_mgr/libvbmeta/utility.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <android-base/logging.h>
+#include <android-base/result.h>
+
+#define VBMETA_TAG "[libvbmeta]"
+#define LWARN LOG(WARNING) << VBMETA_TAG
+#define LINFO LOG(INFO) << VBMETA_TAG
+#define LERROR LOG(ERROR) << VBMETA_TAG
+#define PWARNING PLOG(WARNING) << VBMETA_TAG
+#define PERROR PLOG(ERROR) << VBMETA_TAG
+
+namespace android {
+namespace fs_mgr {
+
+android::base::Result<uint64_t> GetFileSize(int fd);
+
+uint64_t IndexOffset(const uint8_t vbmeta_index);
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/writer.cpp b/fs_mgr/libvbmeta/writer.cpp
new file mode 100644
index 0000000..fc0e0fb
--- /dev/null
+++ b/fs_mgr/libvbmeta/writer.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "writer.h"
+
+#include <android-base/file.h>
+
+#include "utility.h"
+
+using android::base::ErrnoError;
+using android::base::Result;
+
+namespace android {
+namespace fs_mgr {
+
+std::string SerializeVBMetaTable(const VBMetaTable& input) {
+    std::string table;
+    table.append(reinterpret_cast<const char*>(&input.header), SUPER_VBMETA_HEADER_SIZE);
+
+    for (const auto& desc : input.descriptors) {
+        table.append(reinterpret_cast<const char*>(&desc), SUPER_VBMETA_DESCRIPTOR_SIZE);
+        table.append(desc.vbmeta_name);
+    }
+
+    // Ensure the size of vbmeta table is SUPER_VBMETA_TABLE_MAX_SIZE
+    table.resize(SUPER_VBMETA_TABLE_MAX_SIZE, '\0');
+
+    return table;
+}
+
+Result<void> WritePrimaryVBMetaTable(int fd, const std::string& table) {
+    const uint64_t offset = PRIMARY_SUPER_VBMETA_TABLE_OFFSET;
+    if (lseek(fd, offset, SEEK_SET) < 0) {
+        return ErrnoError() << __PRETTY_FUNCTION__ << " lseek failed";
+    }
+
+    if (!android::base::WriteFully(fd, table.data(), table.size())) {
+        return ErrnoError() << "Failed to write primary vbmeta table at offset " << offset;
+    }
+    return {};
+}
+
+Result<void> WriteBackupVBMetaTable(int fd, const std::string& table) {
+    const uint64_t offset = BACKUP_SUPER_VBMETA_TABLE_OFFSET;
+    if (lseek(fd, offset, SEEK_SET) < 0) {
+        return ErrnoError() << __PRETTY_FUNCTION__ << " lseek failed";
+    }
+
+    if (!android::base::WriteFully(fd, table.data(), table.size())) {
+        return ErrnoError() << "Failed to write backup vbmeta table at offset " << offset;
+    }
+    return {};
+}
+
+Result<void> WriteVBMetaImage(int fd, const uint8_t slot_number, const std::string& vbmeta_image) {
+    const uint64_t offset = IndexOffset(slot_number);
+    if (lseek(fd, offset, SEEK_SET) < 0) {
+        return ErrnoError() << __PRETTY_FUNCTION__ << " lseek failed";
+    }
+
+    if (!android::base::WriteFully(fd, vbmeta_image.data(), vbmeta_image.size())) {
+        return ErrnoError() << "Failed to write vbmeta image at offset " << offset;
+    }
+    return {};
+}
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libvbmeta/writer.h b/fs_mgr/libvbmeta/writer.h
new file mode 100644
index 0000000..f8eed36
--- /dev/null
+++ b/fs_mgr/libvbmeta/writer.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <string>
+
+#include <android-base/result.h>
+
+#include "super_vbmeta_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+std::string SerializeVBMetaTable(const VBMetaTable& input);
+
+android::base::Result<void> WritePrimaryVBMetaTable(int fd, const std::string& table);
+android::base::Result<void> WriteBackupVBMetaTable(int fd, const std::string& table);
+android::base::Result<void> WriteVBMetaImage(int fd, const uint8_t slot_number,
+                                             const std::string& vbmeta_image);
+
+}  // namespace fs_mgr
+}  // namespace android
\ No newline at end of file
diff --git a/init/Android.mk b/init/Android.mk
index 359ebf8..62e452f 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -108,7 +108,7 @@
     libgsi \
     libcom.android.sysprop.apex \
     liblzma \
-    libdexfile_support \
+    libdexfile_support_static \
     libunwindstack \
     libbacktrace \
     libmodprobe \
diff --git a/init/README.md b/init/README.md
index 423c6d1..29b972d 100644
--- a/init/README.md
+++ b/init/README.md
@@ -170,6 +170,8 @@
   be changed by setting the "androidboot.console" kernel parameter. In
   all cases the leading "/dev/" should be omitted, so "/dev/tty0" would be
   specified as just "console tty0".
+  This option connects stdin, stdout, and stderr to the console. It is mutually exclusive with the
+  stdio_to_kmsg option, which only connects stdout and stderr to kmsg.
 
 `critical`
 > This is a device-critical service. If it exits more than four times in
@@ -313,6 +315,13 @@
   seclabel or computed based on the service executable file security context.
   For native executables see libcutils android\_get\_control\_socket().
 
+`stdio_to_kmsg`
+> Redirect stdout and stderr to /dev/kmsg_debug. This is useful for services that do not use native
+  Android logging during early boot and whose logs messages we want to capture. This is only enabled
+  when /dev/kmsg_debug is enabled, which is only enabled on userdebug and eng builds.
+  This is mutually exclusive with the console option, which additionally connects stdin to the
+  given console.
+
 `timeout_period <seconds>`
 > Provide a timeout after which point the service will be killed. The oneshot keyword is respected
   here, so oneshot services do not automatically restart, however all other services will.
diff --git a/init/action_parser.cpp b/init/action_parser.cpp
index ff20e43..9736824 100644
--- a/init/action_parser.cpp
+++ b/init/action_parser.cpp
@@ -121,13 +121,8 @@
     }
 
     Subcontext* action_subcontext = nullptr;
-    if (subcontexts_) {
-        for (auto& subcontext : *subcontexts_) {
-            if (StartsWith(filename, subcontext.path_prefix())) {
-                action_subcontext = &subcontext;
-                break;
-            }
-        }
+    if (subcontext_ && subcontext_->PathMatchesSubcontext(filename)) {
+        action_subcontext = subcontext_;
     }
 
     std::string event_trigger;
diff --git a/init/action_parser.h b/init/action_parser.h
index 2fe9983..3000132 100644
--- a/init/action_parser.h
+++ b/init/action_parser.h
@@ -30,8 +30,8 @@
 
 class ActionParser : public SectionParser {
   public:
-    ActionParser(ActionManager* action_manager, std::vector<Subcontext>* subcontexts)
-        : action_manager_(action_manager), subcontexts_(subcontexts), action_(nullptr) {}
+    ActionParser(ActionManager* action_manager, Subcontext* subcontext)
+        : action_manager_(action_manager), subcontext_(subcontext), action_(nullptr) {}
     Result<void> ParseSection(std::vector<std::string>&& args, const std::string& filename,
                               int line) override;
     Result<void> ParseLineSection(std::vector<std::string>&& args, int line) override;
@@ -39,7 +39,7 @@
 
   private:
     ActionManager* action_manager_;
-    std::vector<Subcontext>* subcontexts_;
+    Subcontext* subcontext_;
     std::unique_ptr<Action> action_;
 };
 
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 6b4216f..9121bac 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -50,12 +50,13 @@
 using android::fs_mgr::AvbHandleStatus;
 using android::fs_mgr::AvbHashtreeResult;
 using android::fs_mgr::AvbUniquePtr;
-using android::fs_mgr::BuildGsiSystemFstabEntry;
 using android::fs_mgr::Fstab;
 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::ReadDefaultFstab;
 using android::fs_mgr::ReadFstabFromDt;
 using android::fs_mgr::SkipMountingPartitions;
+using android::fs_mgr::TransformFstabForDsu;
+using android::init::WriteFile;
 using android::snapshot::SnapshotManager;
 
 using namespace std::literals;
@@ -77,8 +78,9 @@
     bool InitDevices();
 
   protected:
-    ListenerAction HandleBlockDevice(const std::string& name, const Uevent&);
-    bool InitRequiredDevices();
+    ListenerAction HandleBlockDevice(const std::string& name, const Uevent&,
+                                     std::set<std::string>* required_devices);
+    bool InitRequiredDevices(std::set<std::string> devices);
     bool InitMappedDevice(const std::string& verity_device);
     bool InitDeviceMapper();
     bool CreateLogicalPartitions();
@@ -89,14 +91,14 @@
     bool TrySwitchSystemAsRoot();
     bool TrySkipMountingPartitions();
     bool IsDmLinearEnabled();
-    bool GetDmLinearMetadataDevice();
+    void GetDmLinearMetadataDevice(std::set<std::string>* devices);
     bool InitDmLinearBackingDevices(const android::fs_mgr::LpMetadata& metadata);
     void UseGsiIfPresent();
 
-    ListenerAction UeventCallback(const Uevent& uevent);
+    ListenerAction UeventCallback(const Uevent& uevent, std::set<std::string>* required_devices);
 
     // Pure virtual functions.
-    virtual bool GetDmVerityDevices() = 0;
+    virtual bool GetDmVerityDevices(std::set<std::string>* devices) = 0;
     virtual bool SetUpDmVerity(FstabEntry* fstab_entry) = 0;
 
     bool need_dm_verity_;
@@ -104,7 +106,6 @@
 
     Fstab fstab_;
     std::string lp_metadata_partition_;
-    std::set<std::string> required_devices_partition_names_;
     std::string super_partition_name_;
     std::unique_ptr<DeviceHandler> device_handler_;
     UeventListener uevent_listener_;
@@ -116,7 +117,7 @@
     ~FirstStageMountVBootV1() override = default;
 
   protected:
-    bool GetDmVerityDevices() override;
+    bool GetDmVerityDevices(std::set<std::string>* devices) override;
     bool SetUpDmVerity(FstabEntry* fstab_entry) override;
 };
 
@@ -128,7 +129,7 @@
     ~FirstStageMountVBootV2() override = default;
 
   protected:
-    bool GetDmVerityDevices() override;
+    bool GetDmVerityDevices(std::set<std::string>* devices) override;
     bool SetUpDmVerity(FstabEntry* fstab_entry) override;
     bool InitAvbHandle();
 
@@ -252,7 +253,13 @@
 }
 
 bool FirstStageMount::InitDevices() {
-    return GetDmLinearMetadataDevice() && GetDmVerityDevices() && InitRequiredDevices();
+    std::set<std::string> devices;
+    GetDmLinearMetadataDevice(&devices);
+
+    if (!GetDmVerityDevices(&devices)) {
+        return false;
+    }
+    return InitRequiredDevices(std::move(devices));
 }
 
 bool FirstStageMount::IsDmLinearEnabled() {
@@ -262,45 +269,46 @@
     return false;
 }
 
-bool FirstStageMount::GetDmLinearMetadataDevice() {
+void FirstStageMount::GetDmLinearMetadataDevice(std::set<std::string>* devices) {
     // Add any additional devices required for dm-linear mappings.
     if (!IsDmLinearEnabled()) {
-        return true;
+        return;
     }
 
-    required_devices_partition_names_.emplace(super_partition_name_);
-    return true;
+    devices->emplace(super_partition_name_);
 }
 
-// Creates devices with uevent->partition_name matching one in the member variable
-// required_devices_partition_names_. Found partitions will then be removed from it
-// for the subsequent member function to check which devices are NOT created.
-bool FirstStageMount::InitRequiredDevices() {
+// Creates devices with uevent->partition_name matching ones in the given set.
+// Found partitions will then be removed from it for the subsequent member
+// function to check which devices are NOT created.
+bool FirstStageMount::InitRequiredDevices(std::set<std::string> devices) {
     if (!InitDeviceMapper()) {
         return false;
     }
 
-    if (required_devices_partition_names_.empty()) {
+    if (devices.empty()) {
         return true;
     }
 
-    auto uevent_callback = [this](const Uevent& uevent) { return UeventCallback(uevent); };
+    auto uevent_callback = [&, this](const Uevent& uevent) {
+        return UeventCallback(uevent, &devices);
+    };
     uevent_listener_.RegenerateUevents(uevent_callback);
 
-    // UeventCallback() will remove found partitions from required_devices_partition_names_.
-    // So if it isn't empty here, it means some partitions are not found.
-    if (!required_devices_partition_names_.empty()) {
+    // UeventCallback() will remove found partitions from |devices|. So if it
+    // isn't empty here, it means some partitions are not found.
+    if (!devices.empty()) {
         LOG(INFO) << __PRETTY_FUNCTION__
                   << ": partition(s) not found in /sys, waiting for their uevent(s): "
-                  << android::base::Join(required_devices_partition_names_, ", ");
+                  << android::base::Join(devices, ", ");
         Timer t;
         uevent_listener_.Poll(uevent_callback, 10s);
         LOG(INFO) << "Wait for partitions returned after " << t;
     }
 
-    if (!required_devices_partition_names_.empty()) {
+    if (!devices.empty()) {
         LOG(ERROR) << __PRETTY_FUNCTION__ << ": partition(s) not found after polling timeout: "
-                   << android::base::Join(required_devices_partition_names_, ", ");
+                   << android::base::Join(devices, ", ");
         return false;
     }
 
@@ -333,27 +341,20 @@
 }
 
 bool FirstStageMount::InitDmLinearBackingDevices(const android::fs_mgr::LpMetadata& metadata) {
+    std::set<std::string> devices;
+
     auto partition_names = android::fs_mgr::GetBlockDevicePartitionNames(metadata);
     for (const auto& partition_name : partition_names) {
         // The super partition was found in the earlier pass.
         if (partition_name == super_partition_name_) {
             continue;
         }
-        required_devices_partition_names_.emplace(partition_name);
+        devices.emplace(partition_name);
     }
-    if (required_devices_partition_names_.empty()) {
+    if (devices.empty()) {
         return true;
     }
-
-    auto uevent_callback = [this](const Uevent& uevent) { return UeventCallback(uevent); };
-    uevent_listener_.RegenerateUevents(uevent_callback);
-
-    if (!required_devices_partition_names_.empty()) {
-        LOG(ERROR) << __PRETTY_FUNCTION__ << ": partition(s) not found after polling timeout: "
-                   << android::base::Join(required_devices_partition_names_, ", ");
-        return false;
-    }
-    return true;
+    return InitRequiredDevices(std::move(devices));
 }
 
 bool FirstStageMount::CreateLogicalPartitions() {
@@ -372,6 +373,11 @@
             return false;
         }
         if (sm->NeedSnapshotsInFirstStageMount()) {
+            // When COW images are present for snapshots, they are stored on
+            // the data partition.
+            if (!InitRequiredDevices({"userdata"})) {
+                return false;
+            }
             return sm->CreateLogicalAndSnapshotPartitions(lp_metadata_partition_);
         }
     }
@@ -387,20 +393,21 @@
     return android::fs_mgr::CreateLogicalPartitions(*metadata.get(), lp_metadata_partition_);
 }
 
-ListenerAction FirstStageMount::HandleBlockDevice(const std::string& name, const Uevent& uevent) {
+ListenerAction FirstStageMount::HandleBlockDevice(const std::string& name, const Uevent& uevent,
+                                                  std::set<std::string>* required_devices) {
     // Matches partition name to create device nodes.
     // Both required_devices_partition_names_ and uevent->partition_name have A/B
     // suffix when A/B is used.
-    auto iter = required_devices_partition_names_.find(name);
-    if (iter != required_devices_partition_names_.end()) {
+    auto iter = required_devices->find(name);
+    if (iter != required_devices->end()) {
         LOG(VERBOSE) << __PRETTY_FUNCTION__ << ": found partition: " << *iter;
         if (IsDmLinearEnabled() && name == super_partition_name_) {
             std::vector<std::string> links = device_handler_->GetBlockDeviceSymlinks(uevent);
             lp_metadata_partition_ = links[0];
         }
-        required_devices_partition_names_.erase(iter);
+        required_devices->erase(iter);
         device_handler_->HandleUevent(uevent);
-        if (required_devices_partition_names_.empty()) {
+        if (required_devices->empty()) {
             return ListenerAction::kStop;
         } else {
             return ListenerAction::kContinue;
@@ -409,18 +416,19 @@
     return ListenerAction::kContinue;
 }
 
-ListenerAction FirstStageMount::UeventCallback(const Uevent& uevent) {
+ListenerAction FirstStageMount::UeventCallback(const Uevent& uevent,
+                                               std::set<std::string>* required_devices) {
     // Ignores everything that is not a block device.
     if (uevent.subsystem != "block") {
         return ListenerAction::kContinue;
     }
 
     if (!uevent.partition_name.empty()) {
-        return HandleBlockDevice(uevent.partition_name, uevent);
+        return HandleBlockDevice(uevent.partition_name, uevent, required_devices);
     } else {
         size_t base_idx = uevent.path.rfind('/');
         if (base_idx != std::string::npos) {
-            return HandleBlockDevice(uevent.path.substr(base_idx + 1), uevent);
+            return HandleBlockDevice(uevent.path.substr(base_idx + 1), uevent, required_devices);
         }
     }
     // Not found a partition or find an unneeded partition, continue to find others.
@@ -577,17 +585,7 @@
     const auto devices = fs_mgr_overlayfs_required_devices(&fstab_);
     for (auto const& device : devices) {
         if (android::base::StartsWith(device, "/dev/block/by-name/")) {
-            required_devices_partition_names_.emplace(basename(device.c_str()));
-            auto uevent_callback = [this](const Uevent& uevent) { return UeventCallback(uevent); };
-            uevent_listener_.RegenerateUevents(uevent_callback);
-            if (!required_devices_partition_names_.empty()) {
-                uevent_listener_.Poll(uevent_callback, 10s);
-                if (!required_devices_partition_names_.empty()) {
-                    LOG(ERROR) << __PRETTY_FUNCTION__
-                               << ": partition(s) not found after polling timeout: "
-                               << android::base::Join(required_devices_partition_names_, ", ");
-                }
-            }
+            InitRequiredDevices({basename(device.c_str())});
         } else {
             InitMappedDevice(device);
         }
@@ -599,14 +597,14 @@
 }
 
 void FirstStageMount::UseGsiIfPresent() {
-    std::string metadata_file, error;
+    std::string error;
 
-    if (!android::gsi::CanBootIntoGsi(&metadata_file, &error)) {
+    if (!android::gsi::CanBootIntoGsi(&error)) {
         LOG(INFO) << "GSI " << error << ", proceeding with normal boot";
         return;
     }
 
-    auto metadata = android::fs_mgr::ReadFromImageFile(metadata_file.c_str());
+    auto metadata = android::fs_mgr::ReadFromImageFile(gsi::kDsuLpMetadataFile);
     if (!metadata) {
         LOG(ERROR) << "GSI partition layout could not be read";
         return;
@@ -630,18 +628,20 @@
         return;
     }
 
-    // Replace the existing system fstab entry.
-    auto system_partition = std::find_if(fstab_.begin(), fstab_.end(), [](const auto& entry) {
-        return entry.mount_point == "/system";
-    });
-    if (system_partition != fstab_.end()) {
-        fstab_.erase(system_partition);
+    std::string lp_names = "";
+    std::vector<std::string> dsu_partitions;
+    for (auto&& partition : metadata->partitions) {
+        auto name = fs_mgr::GetPartitionName(partition);
+        dsu_partitions.push_back(name);
+        lp_names += name + ",";
     }
-    fstab_.emplace_back(BuildGsiSystemFstabEntry());
+    // Publish the logical partition names for TransformFstabForDsu
+    WriteFile(gsi::kGsiLpNamesFile, lp_names);
+    TransformFstabForDsu(&fstab_, dsu_partitions);
     gsi_not_on_userdata_ = (super_name != "userdata");
 }
 
-bool FirstStageMountVBootV1::GetDmVerityDevices() {
+bool FirstStageMountVBootV1::GetDmVerityDevices(std::set<std::string>* devices) {
     need_dm_verity_ = false;
 
     for (const auto& fstab_entry : fstab_) {
@@ -660,7 +660,7 @@
     // Notes that fstab_rec->blk_device has A/B suffix updated by fs_mgr when A/B is used.
     for (const auto& fstab_entry : fstab_) {
         if (!fstab_entry.fs_mgr_flags.logical) {
-            required_devices_partition_names_.emplace(basename(fstab_entry.blk_device.c_str()));
+            devices->emplace(basename(fstab_entry.blk_device.c_str()));
         }
     }
 
@@ -711,7 +711,7 @@
     }
 }
 
-bool FirstStageMountVBootV2::GetDmVerityDevices() {
+bool FirstStageMountVBootV2::GetDmVerityDevices(std::set<std::string>* devices) {
     need_dm_verity_ = false;
 
     std::set<std::string> logical_partitions;
@@ -725,7 +725,7 @@
             // Don't try to find logical partitions via uevent regeneration.
             logical_partitions.emplace(basename(fstab_entry.blk_device.c_str()));
         } else {
-            required_devices_partition_names_.emplace(basename(fstab_entry.blk_device.c_str()));
+            devices->emplace(basename(fstab_entry.blk_device.c_str()));
         }
     }
 
@@ -742,11 +742,11 @@
             if (logical_partitions.count(partition_name)) {
                 continue;
             }
-            // required_devices_partition_names_ is of type std::set so it's not an issue
-            // to emplace a partition twice. e.g., /vendor might be in both places:
+            // devices is of type std::set so it's not an issue to emplace a
+            // partition twice. e.g., /vendor might be in both places:
             //   - device_tree_vbmeta_parts_ = "vbmeta,boot,system,vendor"
             //   - mount_fstab_recs_: /vendor_a
-            required_devices_partition_names_.emplace(partition_name);
+            devices->emplace(partition_name);
         }
     }
     return true;
diff --git a/init/init.cpp b/init/init.cpp
index 8326466..ad31fa0 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -103,7 +103,7 @@
 static bool do_shutdown = false;
 static bool load_debug_prop = false;
 
-static std::vector<Subcontext>* subcontexts;
+static std::unique_ptr<Subcontext> subcontext;
 
 void DumpState() {
     ServiceList::GetInstance().DumpState();
@@ -113,9 +113,10 @@
 Parser CreateParser(ActionManager& action_manager, ServiceList& service_list) {
     Parser parser;
 
-    parser.AddSectionParser(
-            "service", std::make_unique<ServiceParser>(&service_list, subcontexts, std::nullopt));
-    parser.AddSectionParser("on", std::make_unique<ActionParser>(&action_manager, subcontexts));
+    parser.AddSectionParser("service", std::make_unique<ServiceParser>(
+                                               &service_list, subcontext.get(), std::nullopt));
+    parser.AddSectionParser("on",
+                            std::make_unique<ActionParser>(&action_manager, subcontext.get()));
     parser.AddSectionParser("import", std::make_unique<ImportParser>(&parser));
 
     return parser;
@@ -125,8 +126,8 @@
 Parser CreateServiceOnlyParser(ServiceList& service_list) {
     Parser parser;
 
-    parser.AddSectionParser(
-            "service", std::make_unique<ServiceParser>(&service_list, subcontexts, std::nullopt));
+    parser.AddSectionParser("service", std::make_unique<ServiceParser>(
+                                               &service_list, subcontext.get(), std::nullopt));
     return parser;
 }
 
@@ -749,7 +750,7 @@
         PLOG(FATAL) << "SetupMountNamespaces failed";
     }
 
-    subcontexts = InitializeSubcontexts();
+    subcontext = InitializeSubcontext();
 
     ActionManager& am = ActionManager::GetInstance();
     ServiceList& sm = ServiceList::GetInstance();
diff --git a/init/property_service.cpp b/init/property_service.cpp
index c18decc..f5d1143 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -530,7 +530,7 @@
     uint32_t result = 0;
     ucred cr = {.pid = 1, .uid = 0, .gid = 0};
     std::string error;
-    result = HandlePropertySet(name, value, kInitContext.c_str(), cr, nullptr, &error);
+    result = HandlePropertySet(name, value, kInitContext, cr, nullptr, &error);
     if (result != PROP_SUCCESS) {
         LOG(ERROR) << "Init cannot set '" << name << "' to '" << value << "': " << error;
     }
@@ -645,11 +645,16 @@
     char *key, *value, *eol, *sol, *tmp, *fn;
     size_t flen = 0;
 
-    const char* context = kInitContext.c_str();
+    static constexpr const char* const kVendorPathPrefixes[2] = {
+            "/vendor",
+            "/odm",
+    };
+
+    const char* context = kInitContext;
     if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_P__) {
-        for (const auto& [path_prefix, secontext] : paths_and_secontexts) {
-            if (StartsWith(filename, path_prefix)) {
-                context = secontext;
+        for (const auto& vendor_path_prefix : kVendorPathPrefixes) {
+            if (StartsWith(filename, vendor_path_prefix)) {
+                context = kVendorContext;
             }
         }
     }
diff --git a/init/reboot.cpp b/init/reboot.cpp
index 786a084..2cf0f5c 100644
--- a/init/reboot.cpp
+++ b/init/reboot.cpp
@@ -60,6 +60,8 @@
 
 #define PROC_SYSRQ "/proc/sysrq-trigger"
 
+using namespace std::literals;
+
 using android::base::GetBoolProperty;
 using android::base::Split;
 using android::base::Timer;
@@ -170,9 +172,23 @@
                  << stat;
 }
 
-/* Find all read+write block devices and emulated devices in /proc/mounts
- * and add them to correpsponding list.
- */
+static bool IsDataMounted() {
+    std::unique_ptr<std::FILE, int (*)(std::FILE*)> fp(setmntent("/proc/mounts", "re"), endmntent);
+    if (fp == nullptr) {
+        PLOG(ERROR) << "Failed to open /proc/mounts";
+        return false;
+    }
+    mntent* mentry;
+    while ((mentry = getmntent(fp.get())) != nullptr) {
+        if (mentry->mnt_dir == "/data"s) {
+            return true;
+        }
+    }
+    return false;
+}
+
+// Find all read+write block devices and emulated devices in /proc/mounts and add them to
+// the correpsponding list.
 static bool FindPartitionsToUmount(std::vector<MountEntry>* blockDevPartitions,
                                    std::vector<MountEntry>* emulatedPartitions, bool dump) {
     std::unique_ptr<std::FILE, int (*)(std::FILE*)> fp(setmntent("/proc/mounts", "re"), endmntent);
@@ -295,12 +311,15 @@
             LOG(ERROR) << "Reboot thread timed out";
 
             if (android::base::GetBoolProperty("ro.debuggable", false) == true) {
-                LOG(INFO) << "Try to dump init process call trace:";
-                const char* vdc_argv[] = {"/system/bin/debuggerd", "-b", "1"};
-                int status;
-                android_fork_execvp_ext(arraysize(vdc_argv), (char**)vdc_argv, &status, true,
-                                        LOG_KLOG, true, nullptr, nullptr, 0);
-
+                if (false) {
+                    // SEPolicy will block debuggerd from running and this is intentional.
+                    // But these lines are left to be enabled during debugging.
+                    LOG(INFO) << "Try to dump init process call trace:";
+                    const char* vdc_argv[] = {"/system/bin/debuggerd", "-b", "1"};
+                    int status;
+                    android_fork_execvp_ext(arraysize(vdc_argv), (char**)vdc_argv, &status, true,
+                                            LOG_KLOG, true, nullptr, nullptr, 0);
+                }
                 LOG(INFO) << "Show stack for all active CPU:";
                 WriteStringToFile("l", PROC_SYSRQ);
 
@@ -436,6 +455,14 @@
     Timer t;
     LOG(INFO) << "Reboot start, reason: " << reason << ", rebootTarget: " << rebootTarget;
 
+    // If /data isn't mounted then we can skip the extra reboot steps below, since we don't need to
+    // worry about unmounting it.
+    if (!IsDataMounted()) {
+        sync();
+        RebootSystem(cmd, rebootTarget);
+        abort();
+    }
+
     // Ensure last reboot reason is reduced to canonical
     // alias reported in bootloader or system boot reason.
     size_t skip = 0;
diff --git a/init/service.cpp b/init/service.cpp
index 793a2b2..e8b75d4 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -441,6 +441,23 @@
 
     LOG(INFO) << "starting service '" << name_ << "'...";
 
+    std::vector<Descriptor> descriptors;
+    for (const auto& socket : sockets_) {
+        if (auto result = socket.Create(scon)) {
+            descriptors.emplace_back(std::move(*result));
+        } else {
+            LOG(INFO) << "Could not create socket '" << socket.name << "': " << result.error();
+        }
+    }
+
+    for (const auto& file : files_) {
+        if (auto result = file.Create()) {
+            descriptors.emplace_back(std::move(*result));
+        } else {
+            LOG(INFO) << "Could not open file '" << file.name << "': " << result.error();
+        }
+    }
+
     pid_t pid = -1;
     if (namespaces_.flags) {
         pid = clone(nullptr, nullptr, namespaces_.flags | SIGCHLD, nullptr);
@@ -460,16 +477,8 @@
             setenv(key.c_str(), value.c_str(), 1);
         }
 
-        for (const auto& socket : sockets_) {
-            if (auto result = socket.CreateAndPublish(scon); !result) {
-                LOG(INFO) << "Could not create socket '" << socket.name << "': " << result.error();
-            }
-        }
-
-        for (const auto& file : files_) {
-            if (auto result = file.CreateAndPublish(); !result) {
-                LOG(INFO) << "Could not open file '" << file.name << "': " << result.error();
-            }
+        for (const auto& descriptor : descriptors) {
+            descriptor.Publish();
         }
 
         if (auto result = WritePidToFiles(&writepid_files_); !result) {
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index 4322dc7..e7808a9 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -83,6 +83,9 @@
 }
 
 Result<void> ServiceParser::ParseConsole(std::vector<std::string>&& args) {
+    if (service_->proc_attr_.stdio_to_kmsg) {
+        return Error() << "'console' and 'stdio_to_kmsg' are mutually exclusive";
+    }
     service_->flags_ |= SVC_CONSOLE;
     service_->proc_attr_.console = args.size() > 1 ? "/dev/" + args[1] : "";
     return {};
@@ -429,6 +432,14 @@
     return {};
 }
 
+Result<void> ServiceParser::ParseStdioToKmsg(std::vector<std::string>&& args) {
+    if (service_->flags_ & SVC_CONSOLE) {
+        return Error() << "'stdio_to_kmsg' and 'console' are mutually exclusive";
+    }
+    service_->proc_attr_.stdio_to_kmsg = true;
+    return {};
+}
+
 // name type
 Result<void> ServiceParser::ParseFile(std::vector<std::string>&& args) {
     if (args[2] != "r" && args[2] != "w" && args[2] != "rw") {
@@ -514,6 +525,7 @@
         {"shutdown",                {1,     1,    &ServiceParser::ParseShutdown}},
         {"sigstop",                 {0,     0,    &ServiceParser::ParseSigstop}},
         {"socket",                  {3,     6,    &ServiceParser::ParseSocket}},
+        {"stdio_to_kmsg",           {0,     0,    &ServiceParser::ParseStdioToKmsg}},
         {"timeout_period",          {1,     1,    &ServiceParser::ParseTimeoutPeriod}},
         {"updatable",               {0,     0,    &ServiceParser::ParseUpdatable}},
         {"user",                    {1,     1,    &ServiceParser::ParseUser}},
@@ -537,13 +549,8 @@
     filename_ = filename;
 
     Subcontext* restart_action_subcontext = nullptr;
-    if (subcontexts_) {
-        for (auto& subcontext : *subcontexts_) {
-            if (StartsWith(filename, subcontext.path_prefix())) {
-                restart_action_subcontext = &subcontext;
-                break;
-            }
-        }
+    if (subcontext_ && subcontext_->PathMatchesSubcontext(filename)) {
+        restart_action_subcontext = subcontext_;
     }
 
     std::vector<std::string> str_args(args.begin() + 2, args.end());
diff --git a/init/service_parser.h b/init/service_parser.h
index ace4d70..b1281f5 100644
--- a/init/service_parser.h
+++ b/init/service_parser.h
@@ -30,10 +30,10 @@
 class ServiceParser : public SectionParser {
   public:
     ServiceParser(
-            ServiceList* service_list, std::vector<Subcontext>* subcontexts,
+            ServiceList* service_list, Subcontext* subcontext,
             const std::optional<InterfaceInheritanceHierarchyMap>& interface_inheritance_hierarchy)
         : service_list_(service_list),
-          subcontexts_(subcontexts),
+          subcontext_(subcontext),
           interface_inheritance_hierarchy_(interface_inheritance_hierarchy),
           service_(nullptr) {}
     Result<void> ParseSection(std::vector<std::string>&& args, const std::string& filename,
@@ -75,6 +75,7 @@
     Result<void> ParseShutdown(std::vector<std::string>&& args);
     Result<void> ParseSigstop(std::vector<std::string>&& args);
     Result<void> ParseSocket(std::vector<std::string>&& args);
+    Result<void> ParseStdioToKmsg(std::vector<std::string>&& args);
     Result<void> ParseTimeoutPeriod(std::vector<std::string>&& args);
     Result<void> ParseFile(std::vector<std::string>&& args);
     Result<void> ParseUser(std::vector<std::string>&& args);
@@ -84,7 +85,7 @@
     bool IsValidName(const std::string& name) const;
 
     ServiceList* service_list_;
-    std::vector<Subcontext>* subcontexts_;
+    Subcontext* subcontext_;
     std::optional<InterfaceInheritanceHierarchyMap> interface_inheritance_hierarchy_;
     std::unique_ptr<Service> service_;
     std::string filename_;
diff --git a/init/service_utils.cpp b/init/service_utils.cpp
index 836145d..93cffd8 100644
--- a/init/service_utils.cpp
+++ b/init/service_utils.cpp
@@ -16,17 +16,18 @@
 
 #include "service_utils.h"
 
+#include <fcntl.h>
 #include <grp.h>
 #include <sys/mount.h>
 #include <sys/prctl.h>
 #include <sys/wait.h>
+#include <unistd.h>
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
-#include <android-base/unique_fd.h>
 #include <cutils/android_get_control_file.h>
 #include <cutils/sockets.h>
 #include <processgroup/processgroup.h>
@@ -122,11 +123,15 @@
     return {};
 }
 
-void ZapStdio() {
+void SetupStdio(bool stdio_to_kmsg) {
     auto fd = unique_fd{open("/dev/null", O_RDWR | O_CLOEXEC)};
-    dup2(fd, 0);
-    dup2(fd, 1);
-    dup2(fd, 2);
+    dup2(fd, STDIN_FILENO);
+    if (stdio_to_kmsg) {
+        fd.reset(open("/dev/kmsg_debug", O_WRONLY | O_CLOEXEC));
+        if (fd == -1) fd.reset(open("/dev/null", O_WRONLY | O_CLOEXEC));
+    }
+    dup2(fd, STDOUT_FILENO);
+    dup2(fd, STDERR_FILENO);
 }
 
 void OpenConsole(const std::string& console) {
@@ -138,37 +143,44 @@
     dup2(fd, 2);
 }
 
-void PublishDescriptor(const std::string& key, const std::string& name, int fd) {
-    std::string published_name = key + name;
+}  // namespace
+
+void Descriptor::Publish() const {
+    auto published_name = name_;
+
     for (auto& c : published_name) {
         c = isalnum(c) ? c : '_';
     }
 
+    int fd = fd_.get();
+    // For safety, the FD is created as CLOEXEC, so that must be removed before publishing.
+    auto fd_flags = fcntl(fd, F_GETFD);
+    fd_flags &= ~FD_CLOEXEC;
+    if (fcntl(fd, F_SETFD, fd_flags) != 0) {
+        PLOG(ERROR) << "Failed to remove CLOEXEC from '" << published_name << "'";
+    }
+
     std::string val = std::to_string(fd);
     setenv(published_name.c_str(), val.c_str(), 1);
 }
 
-}  // namespace
-
-Result<void> SocketDescriptor::CreateAndPublish(const std::string& global_context) const {
+Result<Descriptor> SocketDescriptor::Create(const std::string& global_context) const {
     const auto& socket_context = context.empty() ? global_context : context;
-    auto result = CreateSocket(name, type, passcred, perm, uid, gid, socket_context);
+    auto result = CreateSocket(name, type | SOCK_CLOEXEC, passcred, perm, uid, gid, socket_context);
     if (!result) {
         return result.error();
     }
 
-    PublishDescriptor(ANDROID_SOCKET_ENV_PREFIX, name, *result);
-
-    return {};
+    return Descriptor(ANDROID_SOCKET_ENV_PREFIX + name, unique_fd(*result));
 }
 
-Result<void> FileDescriptor::CreateAndPublish() const {
+Result<Descriptor> FileDescriptor::Create() const {
     int flags = (type == "r") ? O_RDONLY : (type == "w") ? O_WRONLY : O_RDWR;
 
     // Make sure we do not block on open (eg: devices can chose to block on carrier detect).  Our
     // intention is never to delay launch of a service for such a condition.  The service can
     // perform its own blocking on carrier detect.
-    android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(name.c_str(), flags | O_NONBLOCK)));
+    unique_fd fd(TEMP_FAILURE_RETRY(open(name.c_str(), flags | O_NONBLOCK | O_CLOEXEC)));
 
     if (fd < 0) {
         return ErrnoError() << "Failed to open file '" << name << "'";
@@ -179,9 +191,7 @@
 
     LOG(INFO) << "Opened file '" << name << "', flags " << flags;
 
-    PublishDescriptor(ANDROID_FILE_ENV_PREFIX, name, fd.release());
-
-    return {};
+    return Descriptor(ANDROID_FILE_ENV_PREFIX + name, std::move(fd));
 }
 
 Result<void> EnterNamespaces(const NamespaceInfo& info, const std::string& name, bool pre_apexd) {
@@ -234,7 +244,7 @@
         if (setpgid(0, getpid()) == -1) {
             return ErrnoError() << "setpgid failed";
         }
-        ZapStdio();
+        SetupStdio(attr.stdio_to_kmsg);
     }
 
     for (const auto& rlimit : attr.rlimits) {
diff --git a/init/service_utils.h b/init/service_utils.h
index befce25..3f1071e 100644
--- a/init/service_utils.h
+++ b/init/service_utils.h
@@ -22,6 +22,7 @@
 #include <string>
 #include <vector>
 
+#include <android-base/unique_fd.h>
 #include <cutils/iosched_policy.h>
 
 #include "result.h"
@@ -29,6 +30,18 @@
 namespace android {
 namespace init {
 
+class Descriptor {
+  public:
+    Descriptor(const std::string& name, android::base::unique_fd fd)
+        : name_(name), fd_(std::move(fd)){};
+
+    void Publish() const;
+
+  private:
+    std::string name_;
+    android::base::unique_fd fd_;
+};
+
 struct SocketDescriptor {
     std::string name;
     int type = 0;
@@ -38,14 +51,14 @@
     std::string context;
     bool passcred = false;
 
-    Result<void> CreateAndPublish(const std::string& global_context) const;
+    Result<Descriptor> Create(const std::string& global_context) const;
 };
 
 struct FileDescriptor {
     std::string name;
     std::string type;
 
-    Result<void> CreateAndPublish() const;
+    Result<Descriptor> Create() const;
 };
 
 struct NamespaceInfo {
@@ -64,6 +77,7 @@
     gid_t gid;
     std::vector<gid_t> supp_gids;
     int priority;
+    bool stdio_to_kmsg;
 };
 Result<void> SetProcessAttributes(const ProcessAttributes& attr);
 
diff --git a/init/subcontext.cpp b/init/subcontext.cpp
index ec93b58..79fc372 100644
--- a/init/subcontext.cpp
+++ b/init/subcontext.cpp
@@ -49,15 +49,6 @@
 
 namespace android {
 namespace init {
-
-const std::string kInitContext = "u:r:init:s0";
-const std::string kVendorContext = "u:r:vendor_init:s0";
-
-const char* const paths_and_secontexts[2][2] = {
-    {"/vendor", kVendorContext.c_str()},
-    {"/odm", kVendorContext.c_str()},
-};
-
 namespace {
 
 class SubcontextProcess {
@@ -237,6 +228,15 @@
     Fork();
 }
 
+bool Subcontext::PathMatchesSubcontext(const std::string& path) {
+    for (const auto& prefix : path_prefixes_) {
+        if (StartsWith(path, prefix)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 Result<SubcontextReply> Subcontext::TransmitMessage(const SubcontextCommand& subcontext_command) {
     if (auto result = SendMessage(socket_, subcontext_command); !result) {
         Restart();
@@ -313,13 +313,12 @@
 static std::vector<Subcontext> subcontexts;
 static bool shutting_down;
 
-std::vector<Subcontext>* InitializeSubcontexts() {
+std::unique_ptr<Subcontext> InitializeSubcontext() {
     if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_P__) {
-        for (const auto& [path_prefix, secontext] : paths_and_secontexts) {
-            subcontexts.emplace_back(path_prefix, secontext);
-        }
+        return std::make_unique<Subcontext>(std::vector<std::string>{"/vendor", "/odm"},
+                                            kVendorContext);
     }
-    return &subcontexts;
+    return nullptr;
 }
 
 bool SubcontextChildReap(pid_t pid) {
diff --git a/init/subcontext.h b/init/subcontext.h
index 591521f..bcaad29 100644
--- a/init/subcontext.h
+++ b/init/subcontext.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _INIT_SUBCONTEXT_H
-#define _INIT_SUBCONTEXT_H
+#pragma once
 
 #include <signal.h>
 
@@ -31,22 +30,21 @@
 namespace android {
 namespace init {
 
-extern const std::string kInitContext;
-extern const std::string kVendorContext;
-extern const char* const paths_and_secontexts[2][2];
+static constexpr const char kInitContext[] = "u:r:init:s0";
+static constexpr const char kVendorContext[] = "u:r:vendor_init:s0";
 
 class Subcontext {
   public:
-    Subcontext(std::string path_prefix, std::string context)
-        : path_prefix_(std::move(path_prefix)), context_(std::move(context)), pid_(0) {
+    Subcontext(std::vector<std::string> path_prefixes, std::string context)
+        : path_prefixes_(std::move(path_prefixes)), context_(std::move(context)), pid_(0) {
         Fork();
     }
 
     Result<void> Execute(const std::vector<std::string>& args);
     Result<std::vector<std::string>> ExpandArgs(const std::vector<std::string>& args);
     void Restart();
+    bool PathMatchesSubcontext(const std::string& path);
 
-    const std::string& path_prefix() const { return path_prefix_; }
     const std::string& context() const { return context_; }
     pid_t pid() const { return pid_; }
 
@@ -54,18 +52,16 @@
     void Fork();
     Result<SubcontextReply> TransmitMessage(const SubcontextCommand& subcontext_command);
 
-    std::string path_prefix_;
+    std::vector<std::string> path_prefixes_;
     std::string context_;
     pid_t pid_;
     android::base::unique_fd socket_;
 };
 
 int SubcontextMain(int argc, char** argv, const BuiltinFunctionMap* function_map);
-std::vector<Subcontext>* InitializeSubcontexts();
+std::unique_ptr<Subcontext> InitializeSubcontext();
 bool SubcontextChildReap(pid_t pid);
 void SubcontextTerminate();
 
 }  // namespace init
 }  // namespace android
-
-#endif
diff --git a/init/subcontext_benchmark.cpp b/init/subcontext_benchmark.cpp
index f6fee8a..ccef2f3 100644
--- a/init/subcontext_benchmark.cpp
+++ b/init/subcontext_benchmark.cpp
@@ -33,7 +33,7 @@
         return;
     }
 
-    auto subcontext = Subcontext("path", context);
+    auto subcontext = Subcontext({"path"}, context);
     free(context);
 
     while (state.KeepRunning()) {
diff --git a/init/subcontext_test.cpp b/init/subcontext_test.cpp
index 7565eb6..9cac35e 100644
--- a/init/subcontext_test.cpp
+++ b/init/subcontext_test.cpp
@@ -52,7 +52,7 @@
     auto context_string = std::string(context);
     free(context);
 
-    auto subcontext = Subcontext("dummy_path", context_string);
+    auto subcontext = Subcontext({"dummy_path"}, context_string);
     ASSERT_NE(0, subcontext.pid());
 
     test_function(subcontext, context_string);
diff --git a/init/uevent_listener.cpp b/init/uevent_listener.cpp
index ac633776..416d942 100644
--- a/init/uevent_listener.cpp
+++ b/init/uevent_listener.cpp
@@ -171,7 +171,7 @@
     return RegenerateUeventsForDir(d.get(), callback);
 }
 
-static const char* kRegenerationPaths[] = {"/sys/class", "/sys/block", "/sys/devices"};
+static const char* kRegenerationPaths[] = {"/sys/devices"};
 
 void UeventListener::RegenerateUevents(const ListenerCallback& callback) const {
     for (const auto path : kRegenerationPaths) {
diff --git a/libmeminfo/libmeminfo_test.cpp b/libmeminfo/libmeminfo_test.cpp
index 4c2be91..cf5341d 100644
--- a/libmeminfo/libmeminfo_test.cpp
+++ b/libmeminfo/libmeminfo_test.cpp
@@ -31,6 +31,7 @@
 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>
+#include <android-base/strings.h>
 
 using namespace std;
 using namespace android::meminfo;
@@ -334,7 +335,9 @@
     // Check for names
     EXPECT_EQ(vmas[0].name, "[anon:dalvik-zygote-jit-code-cache]");
     EXPECT_EQ(vmas[1].name, "/system/framework/x86_64/boot-framework.art");
-    EXPECT_EQ(vmas[2].name, "[anon:libc_malloc]");
+    EXPECT_TRUE(vmas[2].name == "[anon:libc_malloc]" ||
+                android::base::StartsWith(vmas[2].name, "[anon:scudo:"))
+            << "Unknown map name " << vmas[2].name;
     EXPECT_EQ(vmas[3].name, "/system/priv-app/SettingsProvider/oat/x86_64/SettingsProvider.odex");
     EXPECT_EQ(vmas[4].name, "/system/lib64/libhwui.so");
     EXPECT_EQ(vmas[5].name, "[vsyscall]");
@@ -432,7 +435,9 @@
     // Check for names
     EXPECT_EQ(vmas[0].name, "[anon:dalvik-zygote-jit-code-cache]");
     EXPECT_EQ(vmas[1].name, "/system/framework/x86_64/boot-framework.art");
-    EXPECT_EQ(vmas[2].name, "[anon:libc_malloc]");
+    EXPECT_TRUE(vmas[2].name == "[anon:libc_malloc]" ||
+                android::base::StartsWith(vmas[2].name, "[anon:scudo:"))
+            << "Unknown map name " << vmas[2].name;
     EXPECT_EQ(vmas[3].name, "/system/priv-app/SettingsProvider/oat/x86_64/SettingsProvider.odex");
     EXPECT_EQ(vmas[4].name, "/system/lib64/libhwui.so");
     EXPECT_EQ(vmas[5].name, "[vsyscall]");
diff --git a/libmemunreachable/MemUnreachable.cpp b/libmemunreachable/MemUnreachable.cpp
index ce937fd..c4add19 100644
--- a/libmemunreachable/MemUnreachable.cpp
+++ b/libmemunreachable/MemUnreachable.cpp
@@ -25,6 +25,7 @@
 #include <unordered_map>
 
 #include <android-base/macros.h>
+#include <android-base/strings.h>
 #include <backtrace.h>
 
 #include "Allocator.h"
@@ -250,7 +251,8 @@
     } else if (mapping_name == current_lib) {
       // .rodata or .data section
       globals_mappings.emplace_back(*it);
-    } else if (mapping_name == "[anon:libc_malloc]") {
+    } else if (mapping_name == "[anon:libc_malloc]" ||
+               android::base::StartsWith(mapping_name, "[anon:scudo:")) {
       // named malloc mapping
       heap_mappings.emplace_back(*it);
     } else if (has_prefix(mapping_name, "[anon:dalvik-")) {
diff --git a/libmemunreachable/ScopedDisableMalloc.h b/libmemunreachable/ScopedDisableMalloc.h
index 655e826..dc863c9 100644
--- a/libmemunreachable/ScopedDisableMalloc.h
+++ b/libmemunreachable/ScopedDisableMalloc.h
@@ -34,8 +34,8 @@
 
   void Disable() {
     if (!disabled_) {
-      malloc_disable();
       disabled_ = true;
+      malloc_disable();
     }
   }
 
@@ -71,8 +71,7 @@
 
 class ScopedDisableMallocTimeout {
  public:
-  explicit ScopedDisableMallocTimeout(
-      std::chrono::milliseconds timeout = std::chrono::milliseconds(2000))
+  explicit ScopedDisableMallocTimeout(std::chrono::milliseconds timeout = std::chrono::seconds(10))
       : timeout_(timeout), timed_out_(false), disable_malloc_() {
     Disable();
   }
diff --git a/libnativeloader/Android.bp b/libnativeloader/Android.bp
index b860db9..939bdd7 100644
--- a/libnativeloader/Android.bp
+++ b/libnativeloader/Android.bp
@@ -63,14 +63,6 @@
     export_include_dirs: ["include"],
 }
 
-// TODO(jiyong) Remove this when its use in the internal master is
-// switched to libnativeloader-headers
-cc_library_headers {
-    name: "libnativeloader-dummy-headers",
-    host_supported: true,
-    export_include_dirs: ["include"],
-}
-
 cc_test {
     name: "libnativeloader_test",
     srcs: [
diff --git a/libpackagelistparser/Android.bp b/libpackagelistparser/Android.bp
index 0740e7d..b56dcdb 100644
--- a/libpackagelistparser/Android.bp
+++ b/libpackagelistparser/Android.bp
@@ -19,4 +19,5 @@
         "libpackagelistparser",
     ],
     test_suites: ["device-tests"],
+    require_root: true,
 }
diff --git a/libsparse/Android.bp b/libsparse/Android.bp
index 2ec4754..88146e9 100644
--- a/libsparse/Android.bp
+++ b/libsparse/Android.bp
@@ -82,3 +82,15 @@
         },
     },
 }
+
+cc_fuzz {
+    name: "sparse_fuzzer",
+    host_supported: false,
+    srcs: [
+        "sparse_fuzzer.cpp",
+    ],
+    static_libs: [
+        "libsparse",
+        "liblog",
+    ],
+}
diff --git a/libsparse/sparse_fuzzer.cpp b/libsparse/sparse_fuzzer.cpp
new file mode 100644
index 0000000..42f331f
--- /dev/null
+++ b/libsparse/sparse_fuzzer.cpp
@@ -0,0 +1,16 @@
+#include "include/sparse/sparse.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size < 2 * sizeof(wchar_t)) return 0;
+
+  int64_t blocksize = 4096;
+  struct sparse_file* file = sparse_file_new(size, blocksize);
+  if (!file) {
+    return 0;
+  }
+
+  unsigned int block = 1;
+  sparse_file_add_data(file, &data, size, block);
+  sparse_file_destroy(file);
+  return 0;
+}
diff --git a/libutils/Looper_test.cpp b/libutils/Looper_test.cpp
index 6fdc0edc..37bdf05 100644
--- a/libutils/Looper_test.cpp
+++ b/libutils/Looper_test.cpp
@@ -11,8 +11,9 @@
 
 #include <utils/threads.h>
 
+// b/141212746 - increased for virtual platforms with higher volatility
 // # of milliseconds to fudge stopwatch measurements
-#define TIMING_TOLERANCE_MS 25
+#define TIMING_TOLERANCE_MS 100
 
 namespace android {
 
diff --git a/libutils/Timers.cpp b/libutils/Timers.cpp
index c3641ef..1172ae7 100644
--- a/libutils/Timers.cpp
+++ b/libutils/Timers.cpp
@@ -22,7 +22,8 @@
 #include <limits.h>
 #include <time.h>
 
-#if defined(__ANDROID__)
+// host linux support requires Linux 2.6.39+
+#if defined(__linux__)
 nsecs_t systemTime(int clock)
 {
     static const clockid_t clocks[] = {
@@ -41,8 +42,7 @@
 nsecs_t systemTime(int /*clock*/)
 {
     // Clock support varies widely across hosts. Mac OS doesn't support
-    // posix clocks, older glibcs don't support CLOCK_BOOTTIME and Windows
-    // is windows.
+    // CLOCK_BOOTTIME, and Windows is windows.
     struct timeval t;
     t.tv_sec = t.tv_usec = 0;
     gettimeofday(&t, nullptr);
diff --git a/libutils/include/utils/ByteOrder.h b/libutils/include/utils/ByteOrder.h
index 44ea13d..9b940e6 100644
--- a/libutils/include/utils/ByteOrder.h
+++ b/libutils/include/utils/ByteOrder.h
@@ -14,10 +14,17 @@
  * limitations under the License.
  */
 
-//
+#pragma once
 
-#ifndef _LIBS_UTILS_BYTE_ORDER_H
-#define _LIBS_UTILS_BYTE_ORDER_H
+/*
+ * If you're looking for a portable <endian.h> that's available on Android,
+ * Linux, macOS, and Windows, see <android-base/endian.h> instead.
+ *
+ * Nothing in this file is useful because all supported Android ABIs are
+ * little-endian and all our code that runs on the host assumes that the host is
+ * also little-endian. What pretense at big-endian support exists is completely
+ * untested and unlikely to actually work.
+ */
 
 #include <stdint.h>
 #include <sys/types.h>
@@ -27,55 +34,12 @@
 #include <netinet/in.h>
 #endif
 
-/*
- * These macros are like the hton/ntoh byte swapping macros,
- * except they allow you to swap to and from the "device" byte
- * order.  The device byte order is the endianness of the target
- * device -- for the ARM CPUs we use today, this is little endian.
- *
- * Note that the byte swapping functions have not been optimized
- * much; performance is currently not an issue for them since the
- * intent is to allow us to avoid byte swapping on the device.
- */
+/* TODO: move this cruft to frameworks/. */
 
-static inline uint32_t android_swap_long(uint32_t v)
-{
-    return (v<<24) | ((v<<8)&0x00FF0000) | ((v>>8)&0x0000FF00) | (v>>24);
-}
+#define dtohl(x) (x)
+#define dtohs(x) (x)
+#define htodl(x) (x)
+#define htods(x) (x)
 
-static inline uint16_t android_swap_short(uint16_t v)
-{
-    return (v<<8) | (v>>8);
-}
-
-#define DEVICE_BYTE_ORDER LITTLE_ENDIAN
-
-#if BYTE_ORDER == DEVICE_BYTE_ORDER
-
-#define	dtohl(x)	(x)
-#define	dtohs(x)	(x)
-#define	htodl(x)	(x)
-#define	htods(x)	(x)
-
-#else
-
-#define	dtohl(x)	(android_swap_long(x))
-#define	dtohs(x)	(android_swap_short(x))
-#define	htodl(x)	(android_swap_long(x))
-#define	htods(x)	(android_swap_short(x))
-
-#endif
-
-#if BYTE_ORDER == LITTLE_ENDIAN
 #define fromlel(x) (x)
-#define fromles(x) (x)
 #define tolel(x) (x)
-#define toles(x) (x)
-#else
-#define fromlel(x) (android_swap_long(x))
-#define fromles(x) (android_swap_short(x))
-#define tolel(x) (android_swap_long(x))
-#define toles(x) (android_swap_short(x))
-#endif
-
-#endif // _LIBS_UTILS_BYTE_ORDER_H
diff --git a/libutils/include/utils/Trace.h b/libutils/include/utils/Trace.h
index 4b9c91e..fec0ffa 100644
--- a/libutils/include/utils/Trace.h
+++ b/libutils/include/utils/Trace.h
@@ -17,7 +17,12 @@
 #ifndef ANDROID_TRACE_H
 #define ANDROID_TRACE_H
 
-#if defined(__ANDROID__)
+#if defined(_WIN32)
+
+#define ATRACE_NAME(...)
+#define ATRACE_CALL()
+
+#else  // !_WIN32
 
 #include <stdint.h>
 
@@ -51,11 +56,6 @@
 
 }  // namespace android
 
-#else // !__ANDROID__
-
-#define ATRACE_NAME(...)
-#define ATRACE_CALL()
-
-#endif // __ANDROID__
+#endif  // _WIN32
 
 #endif // ANDROID_TRACE_H
diff --git a/logd/LogAudit.cpp b/logd/LogAudit.cpp
index 5a375ec..665bd38 100644
--- a/logd/LogAudit.cpp
+++ b/logd/LogAudit.cpp
@@ -160,7 +160,7 @@
     }
     auto search = denial_to_bug.find(scontext + tcontext + tclass);
     if (search != denial_to_bug.end()) {
-        bug_num->assign(" b/" + search->second);
+        bug_num->assign(" " + search->second);
     } else {
         bug_num->assign("");
     }
diff --git a/logd/tests/logd_test.cpp b/logd/tests/logd_test.cpp
index b6c33d7..80625a7 100644
--- a/logd/tests/logd_test.cpp
+++ b/logd/tests/logd_test.cpp
@@ -349,86 +349,6 @@
 }
 #endif
 
-TEST(logd, both) {
-#ifdef __ANDROID__
-    log_msg msg;
-
-    // check if we can read any logs from logd
-    bool user_logger_available = false;
-    bool user_logger_content = false;
-
-    int fd = socket_local_client("logdr", ANDROID_SOCKET_NAMESPACE_RESERVED,
-                                 SOCK_SEQPACKET);
-    if (fd >= 0) {
-        struct sigaction ignore, old_sigaction;
-        memset(&ignore, 0, sizeof(ignore));
-        ignore.sa_handler = caught_signal;
-        sigemptyset(&ignore.sa_mask);
-        sigaction(SIGALRM, &ignore, &old_sigaction);
-        unsigned int old_alarm = alarm(10);
-
-        static const char ask[] = "dumpAndClose lids=0,1,2,3";
-        user_logger_available = write(fd, ask, sizeof(ask)) == sizeof(ask);
-
-        user_logger_content = recv(fd, msg.buf, sizeof(msg), 0) > 0;
-
-        if (user_logger_content) {
-            dump_log_msg("user", &msg, 3, -1);
-        }
-
-        alarm(old_alarm);
-        sigaction(SIGALRM, &old_sigaction, nullptr);
-
-        close(fd);
-    }
-
-    // check if we can read any logs from kernel logger
-    bool kernel_logger_available = false;
-    bool kernel_logger_content = false;
-
-    static const char* loggers[] = {
-        "/dev/log/main",   "/dev/log_main",   "/dev/log/radio",
-        "/dev/log_radio",  "/dev/log/events", "/dev/log_events",
-        "/dev/log/system", "/dev/log_system",
-    };
-
-    for (unsigned int i = 0; i < arraysize(loggers); ++i) {
-        fd = open(loggers[i], O_RDONLY);
-        if (fd < 0) {
-            continue;
-        }
-        kernel_logger_available = true;
-        fcntl(fd, F_SETFL, O_RDONLY | O_NONBLOCK);
-        int result = TEMP_FAILURE_RETRY(read(fd, msg.buf, sizeof(msg)));
-        if (result > 0) {
-            kernel_logger_content = true;
-            dump_log_msg("kernel", &msg, 0, i / 2);
-        }
-        close(fd);
-    }
-
-    static const char yes[] = "\xE2\x9C\x93";
-    static const char no[] = "\xE2\x9c\x98";
-    fprintf(stderr,
-            "LOGGER  Available  Content\n"
-            "user    %-13s%s\n"
-            "kernel  %-13s%s\n"
-            " status %-11s%s\n",
-            (user_logger_available) ? yes : no, (user_logger_content) ? yes : no,
-            (kernel_logger_available) ? yes : no,
-            (kernel_logger_content) ? yes : no,
-            (user_logger_available && kernel_logger_available) ? "ERROR" : "ok",
-            (user_logger_content && kernel_logger_content) ? "ERROR" : "ok");
-
-    EXPECT_EQ(0, user_logger_available && kernel_logger_available);
-    EXPECT_EQ(0, !user_logger_available && !kernel_logger_available);
-    EXPECT_EQ(0, user_logger_content && kernel_logger_content);
-    EXPECT_EQ(0, !user_logger_content && !kernel_logger_content);
-#else
-    GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif
-}
-
 #ifdef __ANDROID__
 // BAD ROBOT
 //   Benchmark threshold are generally considered bad form unless there is
diff --git a/logwrapper/include/logwrap/logwrap.h b/logwrapper/include/logwrap/logwrap.h
index d3538b3..b1f6410 100644
--- a/logwrapper/include/logwrap/logwrap.h
+++ b/logwrapper/include/logwrap/logwrap.h
@@ -15,8 +15,7 @@
  * limitations under the License.
  */
 
-#ifndef __LIBS_LOGWRAP_H
-#define __LIBS_LOGWRAP_H
+#pragma once
 
 #include <stdbool.h>
 #include <stdint.h>
@@ -26,12 +25,6 @@
 /*
  * Run a command while logging its stdout and stderr
  *
- * WARNING: while this function is running it will clear all SIGCHLD handlers
- * if you rely on SIGCHLD in the caller there is a chance zombies will be
- * created if you're not calling waitpid after calling this. This function will
- * log a warning when it clears SIGCHLD for processes other than the child it
- * created.
- *
  * Arguments:
  *   argc:   the number of elements in argv
  *   argv:   an array of strings containing the command to be executed and its
@@ -40,10 +33,10 @@
  *   status: the equivalent child status as populated by wait(status). This
  *           value is only valid when logwrap successfully completes. If NULL
  *           the return value of the child will be the function's return value.
- *   ignore_int_quit: set to true if you want to completely ignore SIGINT and
- *           SIGQUIT while logwrap is running. This may force the end-user to
- *           send a signal twice to signal the caller (once for the child, and
- *           once for the caller)
+ *   forward_signals: set to true if you want to forward SIGINT, SIGQUIT, and
+ *           SIGHUP to the child process, while it is running.  You likely do
+ *           not need to use this; it is primarily for the logwrapper
+ *           executable itself.
  *   log_target: Specify where to log the output of the child, either LOG_NONE,
  *           LOG_ALOG (for the Android system log), LOG_KLOG (for the kernel
  *           log), or LOG_FILE (and you need to specify a pathname in the
@@ -54,8 +47,6 @@
  *           the specified log until the child has exited.
  *   file_path: if log_target has the LOG_FILE bit set, then this parameter
  *           must be set to the pathname of the file to log to.
- *   unused_opts: currently unused.
- *   unused_opts_len: currently unused.
  *
  * Return value:
  *   0 when logwrap successfully run the child process and captured its status
@@ -71,10 +62,18 @@
 #define LOG_KLOG        2
 #define LOG_FILE        4
 
-// TODO: Remove unused_opts / unused_opts_len in a followup change.
-int android_fork_execvp_ext(int argc, char* argv[], int *status, bool ignore_int_quit,
-        int log_target, bool abbreviated, char *file_path, void* unused_opts,
-        int unused_opts_len);
+int android_fork_execvp_ext2(int argc, char* argv[], int* status, bool forward_signals,
+                             int log_target, bool abbreviated, char* file_path);
+
+// TODO: Actually deprecate this and the below.
+static inline int android_fork_execvp_ext(int argc, char* argv[], int* status, bool ignore_int_quit,
+                                          int log_target, bool abbreviated, char* file_path,
+                                          void* unused_opts, int unused_opts_len) {
+    (void)ignore_int_quit;
+    (void)unused_opts;
+    (void)unused_opts_len;
+    return android_fork_execvp_ext2(argc, argv, status, false, log_target, abbreviated, file_path);
+}
 
 /* Similar to above, except abbreviated logging is not available, and if logwrap
  * is true, logging is to the Android system log, and if false, there is no
@@ -89,5 +88,3 @@
 }
 
 __END_DECLS
-
-#endif /* __LIBS_LOGWRAP_H */
diff --git a/logwrapper/logwrap.c b/logwrapper/logwrap.c
index 8621993..0314f37 100644
--- a/logwrapper/logwrap.c
+++ b/logwrapper/logwrap.c
@@ -36,6 +36,11 @@
 #define MIN(a,b) (((a)<(b))?(a):(b))
 
 static pthread_mutex_t fd_mutex = PTHREAD_MUTEX_INITIALIZER;
+// Protected by fd_mutex.  These signals must be blocked while modifying as well.
+static pid_t child_pid;
+static struct sigaction old_int;
+static struct sigaction old_quit;
+static struct sigaction old_hup;
 
 #define ERROR(fmt, args...)                                                   \
 do {                                                                          \
@@ -289,8 +294,47 @@
     }
 }
 
-static int parent(const char *tag, int parent_read, pid_t pid,
-        int *chld_sts, int log_target, bool abbreviated, char *file_path) {
+static void signal_handler(int signal_num);
+
+static void block_signals(sigset_t* oldset) {
+    sigset_t blockset;
+
+    sigemptyset(&blockset);
+    sigaddset(&blockset, SIGINT);
+    sigaddset(&blockset, SIGQUIT);
+    sigaddset(&blockset, SIGHUP);
+    pthread_sigmask(SIG_BLOCK, &blockset, oldset);
+}
+
+static void unblock_signals(sigset_t* oldset) {
+    pthread_sigmask(SIG_SETMASK, oldset, NULL);
+}
+
+static void setup_signal_handlers(pid_t pid) {
+    struct sigaction handler = {.sa_handler = signal_handler};
+
+    child_pid = pid;
+    sigaction(SIGINT, &handler, &old_int);
+    sigaction(SIGQUIT, &handler, &old_quit);
+    sigaction(SIGHUP, &handler, &old_hup);
+}
+
+static void restore_signal_handlers() {
+    sigaction(SIGINT, &old_int, NULL);
+    sigaction(SIGQUIT, &old_quit, NULL);
+    sigaction(SIGHUP, &old_hup, NULL);
+    child_pid = 0;
+}
+
+static void signal_handler(int signal_num) {
+    if (child_pid == 0 || kill(child_pid, signal_num) != 0) {
+        restore_signal_handlers();
+        raise(signal_num);
+    }
+}
+
+static int parent(const char* tag, int parent_read, pid_t pid, int* chld_sts, int log_target,
+                  bool abbreviated, char* file_path, bool forward_signals) {
     int status = 0;
     char buffer[4096];
     struct pollfd poll_fds[] = {
@@ -308,6 +352,11 @@
     int b = 0;  // end index of unprocessed data
     int sz;
     bool found_child = false;
+    // There is a very small chance that opening child_ptty in the child will fail, but in this case
+    // POLLHUP will not be generated below.  Therefore, we use a 1 second timeout for poll() until
+    // we receive a message from child_ptty.  If this times out, we call waitpid() with WNOHANG to
+    // check the status of the child process and exit appropriately if it has terminated.
+    bool received_messages = false;
     char tmpbuf[256];
 
     log_info.btag = basename(tag);
@@ -347,13 +396,15 @@
     log_info.abbreviated = abbreviated;
 
     while (!found_child) {
-        if (TEMP_FAILURE_RETRY(poll(poll_fds, ARRAY_SIZE(poll_fds), -1)) < 0) {
+        int timeout = received_messages ? -1 : 1000;
+        if (TEMP_FAILURE_RETRY(poll(poll_fds, ARRAY_SIZE(poll_fds), timeout)) < 0) {
             ERROR("poll failed\n");
             rc = -1;
             goto err_poll;
         }
 
         if (poll_fds[0].revents & POLLIN) {
+            received_messages = true;
             sz = TEMP_FAILURE_RETRY(
                 read(parent_read, &buffer[b], sizeof(buffer) - 1 - b));
 
@@ -396,10 +447,20 @@
             }
         }
 
-        if (poll_fds[0].revents & POLLHUP) {
+        if (!received_messages || (poll_fds[0].revents & POLLHUP)) {
             int ret;
+            sigset_t oldset;
 
-            ret = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
+            if (forward_signals) {
+                // Our signal handlers forward these signals to 'child_pid', but waitpid() may reap
+                // the child, so we must block these signals until we either 1) conclude that the
+                // child is still running or 2) determine the child has been reaped and we have
+                // reset the signals to their original disposition.
+                block_signals(&oldset);
+            }
+
+            int flags = (poll_fds[0].revents & POLLHUP) ? 0 : WNOHANG;
+            ret = TEMP_FAILURE_RETRY(waitpid(pid, &status, flags));
             if (ret < 0) {
                 rc = errno;
                 ALOG(LOG_ERROR, "logwrap", "waitpid failed with %s\n", strerror(errno));
@@ -408,6 +469,13 @@
             if (ret > 0) {
                 found_child = true;
             }
+
+            if (forward_signals) {
+                if (found_child) {
+                    restore_signal_handlers();
+                }
+                unblock_signals(&oldset);
+            }
         }
     }
 
@@ -472,21 +540,14 @@
     }
 }
 
-int android_fork_execvp_ext(int argc, char* argv[], int *status, bool ignore_int_quit,
-        int log_target, bool abbreviated, char *file_path,
-        void *unused_opts, int unused_opts_len) {
+int android_fork_execvp_ext2(int argc, char* argv[], int* status, bool forward_signals,
+                             int log_target, bool abbreviated, char* file_path) {
     pid_t pid;
     int parent_ptty;
-    int child_ptty;
-    struct sigaction intact;
-    struct sigaction quitact;
     sigset_t blockset;
     sigset_t oldset;
     int rc = 0;
 
-    LOG_ALWAYS_FATAL_IF(unused_opts != NULL);
-    LOG_ALWAYS_FATAL_IF(unused_opts_len != 0);
-
     rc = pthread_mutex_lock(&fd_mutex);
     if (rc) {
         ERROR("failed to lock signal_fd mutex\n");
@@ -494,7 +555,7 @@
     }
 
     /* Use ptty instead of socketpair so that STDOUT is not buffered */
-    parent_ptty = TEMP_FAILURE_RETRY(open("/dev/ptmx", O_RDWR));
+    parent_ptty = TEMP_FAILURE_RETRY(posix_openpt(O_RDWR | O_CLOEXEC));
     if (parent_ptty < 0) {
         ERROR("Cannot create parent ptty\n");
         rc = -1;
@@ -509,27 +570,26 @@
         goto err_ptty;
     }
 
-    child_ptty = TEMP_FAILURE_RETRY(open(child_devname, O_RDWR));
-    if (child_ptty < 0) {
-        ERROR("Cannot open child_ptty\n");
-        rc = -1;
-        goto err_child_ptty;
+    if (forward_signals) {
+        // Block these signals until we have the child pid and our signal handlers set up.
+        block_signals(&oldset);
     }
 
-    sigemptyset(&blockset);
-    sigaddset(&blockset, SIGINT);
-    sigaddset(&blockset, SIGQUIT);
-    pthread_sigmask(SIG_BLOCK, &blockset, &oldset);
-
     pid = fork();
     if (pid < 0) {
-        close(child_ptty);
         ERROR("Failed to fork\n");
         rc = -1;
         goto err_fork;
     } else if (pid == 0) {
         pthread_mutex_unlock(&fd_mutex);
-        pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+        unblock_signals(&oldset);
+
+        setsid();
+
+        int child_ptty = TEMP_FAILURE_RETRY(open(child_devname, O_RDWR | O_CLOEXEC));
+        if (child_ptty < 0) {
+            FATAL_CHILD("Cannot open child_ptty: %s\n", strerror(errno));
+        }
         close(parent_ptty);
 
         dup2(child_ptty, 1);
@@ -538,27 +598,23 @@
 
         child(argc, argv);
     } else {
-        close(child_ptty);
-        if (ignore_int_quit) {
-            struct sigaction ignact;
-
-            memset(&ignact, 0, sizeof(ignact));
-            ignact.sa_handler = SIG_IGN;
-            sigaction(SIGINT, &ignact, &intact);
-            sigaction(SIGQUIT, &ignact, &quitact);
+        if (forward_signals) {
+            setup_signal_handlers(pid);
+            unblock_signals(&oldset);
         }
 
-        rc = parent(argv[0], parent_ptty, pid, status, log_target,
-                    abbreviated, file_path);
+        rc = parent(argv[0], parent_ptty, pid, status, log_target, abbreviated, file_path,
+                    forward_signals);
+
+        if (forward_signals) {
+            restore_signal_handlers();
+        }
     }
 
-    if (ignore_int_quit) {
-        sigaction(SIGINT, &intact, NULL);
-        sigaction(SIGQUIT, &quitact, NULL);
-    }
 err_fork:
-    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
-err_child_ptty:
+    if (forward_signals) {
+        unblock_signals(&oldset);
+    }
 err_ptty:
     close(parent_ptty);
 err_open:
diff --git a/logwrapper/logwrapper.c b/logwrapper/logwrapper.c
index 33454c6..e786609 100644
--- a/logwrapper/logwrapper.c
+++ b/logwrapper/logwrapper.c
@@ -79,8 +79,7 @@
         usage();
     }
 
-    rc = android_fork_execvp_ext(argc, &argv[0], &status, true,
-                                 log_target, abbreviated, NULL, NULL, 0);
+    rc = android_fork_execvp_ext2(argc, &argv[0], &status, true, log_target, abbreviated, NULL);
     if (!rc) {
         if (WIFEXITED(status))
             rc = WEXITSTATUS(status);
diff --git a/property_service/libpropertyinfoserializer/Android.bp b/property_service/libpropertyinfoserializer/Android.bp
index 51c1226..aa02a3a 100644
--- a/property_service/libpropertyinfoserializer/Android.bp
+++ b/property_service/libpropertyinfoserializer/Android.bp
@@ -1,7 +1,6 @@
 cc_defaults {
     name: "propertyinfoserializer_defaults",
     host_supported: true,
-    vendor_available: true,
     cpp_std: "experimental",
     cppflags: [
         "-Wall",
@@ -9,8 +8,8 @@
         "-Werror",
     ],
     static_libs: [
-        "libpropertyinfoparser",
         "libbase",
+        "libpropertyinfoparser",
     ],
 }
 
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index df1d929..7097a12 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -334,6 +334,15 @@
 LOCAL_MODULE_STEM := ld.config.txt
 include $(BUILD_PREBUILT)
 
+# Returns the unique installed basenames of a module, or module.so if there are
+# none.  The guess is to handle cases like libc, where the module itself is
+# marked uninstallable but a symlink is installed with the name libc.so.
+# $(1): list of libraries
+# $(2): suffix to to add to each library (not used for guess)
+define module-installed-files-or-guess
+$(foreach lib,$(1),$(or $(strip $(sort $(notdir $(call module-installed-files,$(lib)$(2))))),$(lib).so))
+endef
+
 #######################################
 # llndk.libraries.txt
 include $(CLEAR_VARS)
@@ -342,13 +351,13 @@
 LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)
 LOCAL_MODULE_STEM := $(call append_vndk_version,$(LOCAL_MODULE))
 include $(BUILD_SYSTEM)/base_rules.mk
-$(LOCAL_BUILT_MODULE): PRIVATE_LLNDK_LIBRARIES := $(LLNDK_LIBRARIES)
+$(LOCAL_BUILT_MODULE): PRIVATE_LLNDK_LIBRARIES := $(call module-installed-files-or-guess,$(LLNDK_LIBRARIES),)
 $(LOCAL_BUILT_MODULE):
 	@echo "Generate: $@"
 	@mkdir -p $(dir $@)
 	$(hide) echo -n > $@
 	$(hide) $(foreach lib,$(PRIVATE_LLNDK_LIBRARIES), \
-		echo $(lib).so >> $@;)
+		echo $(lib) >> $@;)
 
 #######################################
 # vndksp.libraries.txt
@@ -358,13 +367,13 @@
 LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)
 LOCAL_MODULE_STEM := $(call append_vndk_version,$(LOCAL_MODULE))
 include $(BUILD_SYSTEM)/base_rules.mk
-$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_SAMEPROCESS_LIBRARIES := $(VNDK_SAMEPROCESS_LIBRARIES)
+$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_SAMEPROCESS_LIBRARIES := $(call module-installed-files-or-guess,$(VNDK_SAMEPROCESS_LIBRARIES),.vendor)
 $(LOCAL_BUILT_MODULE):
 	@echo "Generate: $@"
 	@mkdir -p $(dir $@)
 	$(hide) echo -n > $@
 	$(hide) $(foreach lib,$(PRIVATE_VNDK_SAMEPROCESS_LIBRARIES), \
-		echo $(lib).so >> $@;)
+		echo $(lib) >> $@;)
 
 #######################################
 # vndkcore.libraries.txt
@@ -374,13 +383,13 @@
 LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)
 LOCAL_MODULE_STEM := $(call append_vndk_version,$(LOCAL_MODULE))
 include $(BUILD_SYSTEM)/base_rules.mk
-$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_CORE_LIBRARIES := $(VNDK_CORE_LIBRARIES)
+$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_CORE_LIBRARIES := $(call module-installed-files-or-guess,$(VNDK_CORE_LIBRARIES),.vendor)
 $(LOCAL_BUILT_MODULE):
 	@echo "Generate: $@"
 	@mkdir -p $(dir $@)
 	$(hide) echo -n > $@
 	$(hide) $(foreach lib,$(PRIVATE_VNDK_CORE_LIBRARIES), \
-		echo $(lib).so >> $@;)
+		echo $(lib) >> $@;)
 
 #######################################
 # vndkprivate.libraries.txt
@@ -390,13 +399,13 @@
 LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)
 LOCAL_MODULE_STEM := $(call append_vndk_version,$(LOCAL_MODULE))
 include $(BUILD_SYSTEM)/base_rules.mk
-$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_PRIVATE_LIBRARIES := $(VNDK_PRIVATE_LIBRARIES)
+$(LOCAL_BUILT_MODULE): PRIVATE_VNDK_PRIVATE_LIBRARIES := $(call module-installed-files-or-guess,$(VNDK_PRIVATE_LIBRARIES),.vendor)
 $(LOCAL_BUILT_MODULE):
 	@echo "Generate: $@"
 	@mkdir -p $(dir $@)
 	$(hide) echo -n > $@
 	$(hide) $(foreach lib,$(PRIVATE_VNDK_PRIVATE_LIBRARIES), \
-		echo $(lib).so >> $@;)
+		echo $(lib) >> $@;)
 
 #######################################
 # sanitizer.libraries.txt
diff --git a/rootdir/avb/Android.bp b/rootdir/avb/Android.bp
new file mode 100644
index 0000000..85d2786
--- /dev/null
+++ b/rootdir/avb/Android.bp
@@ -0,0 +1,20 @@
+filegroup {
+    name: "q-gsi_avbpubkey",
+    srcs: [
+        "q-gsi.avbpubkey",
+    ],
+}
+
+filegroup {
+    name: "r-gsi_avbpubkey",
+    srcs: [
+        "r-gsi.avbpubkey",
+    ],
+}
+
+filegroup {
+    name: "s-gsi_avbpubkey",
+    srcs: [
+        "s-gsi.avbpubkey",
+    ],
+}
diff --git a/rootdir/etc/ld.config.legacy.txt b/rootdir/etc/ld.config.legacy.txt
index e598f05..bb8d4d0 100644
--- a/rootdir/etc/ld.config.legacy.txt
+++ b/rootdir/etc/ld.config.legacy.txt
@@ -80,16 +80,14 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 # Visible to allow links to be created at runtime, e.g. through
 # android_link_namespaces in libnativeloader.
 namespace.runtime.visible = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # Need allow_all_shared_libs because libart.so can dlopen oat files in
 # /system/framework and /data.
@@ -181,6 +179,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
diff --git a/rootdir/etc/ld.config.txt b/rootdir/etc/ld.config.txt
index e1da587..60035aa 100644
--- a/rootdir/etc/ld.config.txt
+++ b/rootdir/etc/ld.config.txt
@@ -161,16 +161,14 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 # Visible to allow links to be created at runtime, e.g. through
 # android_link_namespaces in libnativeloader.
 namespace.runtime.visible = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # Need allow_all_shared_libs because libart.so can dlopen oat files in
 # /system/framework and /data.
@@ -422,6 +420,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
@@ -490,13 +489,11 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = system
 # TODO(b/130340935): Use a dynamically created linker namespace similar to
 # classloader-namespace for oat files, and tighten this up.
@@ -645,6 +642,7 @@
 namespace.neuralnetworks.link.system.shared_libs += liblog.so
 namespace.neuralnetworks.link.system.shared_libs += libm.so
 namespace.neuralnetworks.link.system.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.system.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.system.shared_libs += libsync.so
 namespace.neuralnetworks.link.system.shared_libs += libvndksupport.so
 
@@ -697,16 +695,14 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 # Visible to allow links to be created at runtime, e.g. through
 # android_link_namespaces in libnativeloader.
 namespace.runtime.visible = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # TODO(b/130340935): Use a dynamically created linker namespace similar to
 # classloader-namespace for oat files, and tighten this up.
@@ -788,6 +784,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
diff --git a/rootdir/etc/ld.config.vndk_lite.txt b/rootdir/etc/ld.config.vndk_lite.txt
index 4beabd6..b9b95a6 100644
--- a/rootdir/etc/ld.config.vndk_lite.txt
+++ b/rootdir/etc/ld.config.vndk_lite.txt
@@ -100,16 +100,14 @@
 # This namespace pulls in externally accessible libs from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 # Visible to allow links to be created at runtime, e.g. through
 # android_link_namespaces in libnativeloader.
 namespace.runtime.visible = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # Need allow_all_shared_libs because libart.so can dlopen oat files in
 # /system/framework and /data.
@@ -346,6 +344,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
@@ -420,13 +419,11 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # TODO(b/130340935): Use a dynamically created linker namespace similar to
 # classloader-namespace for oat files, and tighten this up.
@@ -449,6 +446,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
@@ -504,16 +502,14 @@
 # This namespace exposes externally accessible libraries from the Runtime APEX.
 # Keep in sync with the "runtime" namespace in art/build/apex/ld.config.txt.
 ###############################################################################
+# TODO(b/139408016): Rename this namespace to "art".
 namespace.runtime.isolated = true
 # Visible to allow links to be created at runtime, e.g. through
 # android_link_namespaces in libnativeloader.
 namespace.runtime.visible = true
 
-# TODO(b/139408016): Split the namespaces for the ART and Runtime APEXes
-namespace.runtime.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.search.paths += /apex/com.android.runtime/${LIB}
-namespace.runtime.asan.search.paths  = /apex/com.android.art/${LIB}
-namespace.runtime.asan.search.paths += /apex/com.android.runtime/${LIB}
+namespace.runtime.search.paths = /apex/com.android.art/${LIB}
+namespace.runtime.asan.search.paths = /apex/com.android.art/${LIB}
 namespace.runtime.links = default
 # TODO(b/130340935): Use a dynamically created linker namespace similar to
 # classloader-namespace for oat files, and tighten this up.
@@ -591,6 +587,7 @@
 namespace.neuralnetworks.link.default.shared_libs += liblog.so
 namespace.neuralnetworks.link.default.shared_libs += libm.so
 namespace.neuralnetworks.link.default.shared_libs += libnativewindow.so
+namespace.neuralnetworks.link.default.shared_libs += libneuralnetworks_packageinfo.so
 namespace.neuralnetworks.link.default.shared_libs += libsync.so
 namespace.neuralnetworks.link.default.shared_libs += libvndksupport.so
 
diff --git a/rootdir/init.environ.rc.in b/rootdir/init.environ.rc.in
index 17f6596..50005d9 100644
--- a/rootdir/init.environ.rc.in
+++ b/rootdir/init.environ.rc.in
@@ -5,7 +5,7 @@
     export ANDROID_ASSETS /system/app
     export ANDROID_DATA /data
     export ANDROID_STORAGE /storage
-    export ANDROID_RUNTIME_ROOT /apex/com.android.art
+    export ANDROID_ART_ROOT /apex/com.android.art
     export ANDROID_I18N_ROOT /apex/com.android.i18n
     export ANDROID_TZDATA_ROOT /apex/com.android.tzdata
     export EXTERNAL_STORAGE /sdcard
diff --git a/rootdir/init.rc b/rootdir/init.rc
index a15b501..c61fd90 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -68,19 +68,23 @@
 
 service boringssl_self_test32 /system/bin/boringssl_self_test32
     setenv BORINGSSL_SELF_TEST_CREATE_FLAG true # Any nonempty value counts as true
-    reboot_on_failure reboot,bootloader,boringssl-self-check-failed
+    reboot_on_failure reboot,boringssl-self-check-failed
+    stdio_to_kmsg
 
 service boringssl_self_test64 /system/bin/boringssl_self_test64
     setenv BORINGSSL_SELF_TEST_CREATE_FLAG true # Any nonempty value counts as true
-    reboot_on_failure reboot,bootloader,boringssl-self-check-failed
+    reboot_on_failure reboot,boringssl-self-check-failed
+    stdio_to_kmsg
 
 service boringssl_self_test_apex32 /apex/com.android.conscrypt/bin/boringssl_self_test32
     setenv BORINGSSL_SELF_TEST_CREATE_FLAG true # Any nonempty value counts as true
-    reboot_on_failure reboot,bootloader,boringssl-self-check-failed
+    reboot_on_failure reboot,boringssl-self-check-failed
+    stdio_to_kmsg
 
 service boringssl_self_test_apex64 /apex/com.android.conscrypt/bin/boringssl_self_test64
     setenv BORINGSSL_SELF_TEST_CREATE_FLAG true # Any nonempty value counts as true
-    reboot_on_failure reboot,bootloader,boringssl-self-check-failed
+    reboot_on_failure reboot,boringssl-self-check-failed
+    stdio_to_kmsg
 
 on init
     sysclktz 0
@@ -154,6 +158,14 @@
     mkdir /mnt/user/0/self 0755 root root
     mkdir /mnt/user/0/emulated 0755 root root
     mkdir /mnt/user/0/emulated/0 0755 root root
+
+    # Prepare directories for pass through processes
+    mkdir /mnt/pass_through 0755 root root
+    mkdir /mnt/pass_through/0 0755 root root
+    mkdir /mnt/pass_through/0/self 0755 root root
+    mkdir /mnt/pass_through/0/emulated 0755 root root
+    mkdir /mnt/pass_through/0/emulated/0 0755 root root
+
     mkdir /mnt/expand 0771 system system
     mkdir /mnt/appfuse 0711 root root
 
@@ -678,6 +690,8 @@
   # Mount default storage into root namespace
   mount none /mnt/user/0 /storage bind rec
   mount none none /storage slave rec
+  # Bootstrap the emulated volume for the pass_through directory for user 0
+  mount none /data/media /mnt/pass_through/0/emulated bind rec
 on zygote-start && property:persist.sys.fuse=false
   # Mount default storage into root namespace
   mount none /mnt/runtime/default /storage bind rec
diff --git a/rootdir/update_and_install_ld_config.mk b/rootdir/update_and_install_ld_config.mk
index 9d131dc..c4b8e4e 100644
--- a/rootdir/update_and_install_ld_config.mk
+++ b/rootdir/update_and_install_ld_config.mk
@@ -128,7 +128,7 @@
 deps := $(llndk_libraries_file) $(vndksp_libraries_file) $(vndkcore_libraries_file) \
   $(vndkprivate_libraries_file)
 ifeq ($(check_backward_compatibility),true)
-deps += $(compatibility_check_script)
+deps += $(compatibility_check_script) $(wildcard prebuilts/vndk/*/*/configs/ld.config.*.txt)
 endif
 ifeq ($(my_vndk_use_core_variant),true)
 $(LOCAL_BUILT_MODULE): PRIVATE_VNDK_USING_CORE_VARIANT_LIBRARIES_FILE := $(vndk_using_core_variant_libraries_file)