diff --git a/adb/Android.bp b/adb/Android.bp
index 87e4adc..114eb2a 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -26,6 +26,7 @@
         "-Wvla",
         "-DADB_HOST=1",         // overridden by adbd_defaults
         "-DALLOW_ADBD_ROOT=0",  // overridden by adbd_defaults
+        "-DANDROID_BASE_UNIQUE_FD_DISABLE_IMPLICIT_CONVERSION=1",
     ],
     cpp_std: "experimental",
 
diff --git a/adb/adb_io.cpp b/adb/adb_io.cpp
index f5cdcb5..bdb8efa 100644
--- a/adb/adb_io.cpp
+++ b/adb/adb_io.cpp
@@ -34,7 +34,7 @@
 #include "adb_utils.h"
 #include "sysdeps.h"
 
-bool SendProtocolString(int fd, std::string_view s) {
+bool SendProtocolString(borrowed_fd fd, std::string_view s) {
     unsigned int length = s.size();
     if (length > MAX_PAYLOAD - 4) {
         errno = EMSGSIZE;
@@ -47,7 +47,7 @@
     return WriteFdExactly(fd, str);
 }
 
-bool ReadProtocolString(int fd, std::string* s, std::string* error) {
+bool ReadProtocolString(borrowed_fd fd, std::string* s, std::string* error) {
     char buf[5];
     if (!ReadFdExactly(fd, buf, 4)) {
         *error = perror_str("protocol fault (couldn't read status length)");
@@ -65,57 +65,57 @@
     return true;
 }
 
-bool SendOkay(int fd) {
+bool SendOkay(borrowed_fd fd) {
     return WriteFdExactly(fd, "OKAY", 4);
 }
 
-bool SendFail(int fd, std::string_view reason) {
+bool SendFail(borrowed_fd fd, std::string_view reason) {
     return WriteFdExactly(fd, "FAIL", 4) && SendProtocolString(fd, reason);
 }
 
-bool ReadFdExactly(int fd, void* buf, size_t len) {
+bool ReadFdExactly(borrowed_fd fd, void* buf, size_t len) {
     char* p = reinterpret_cast<char*>(buf);
 
     size_t len0 = len;
 
-    D("readx: fd=%d wanted=%zu", fd, len);
+    D("readx: fd=%d wanted=%zu", fd.get(), len);
     while (len > 0) {
         int r = adb_read(fd, p, len);
         if (r > 0) {
             len -= r;
             p += r;
         } else if (r == -1) {
-            D("readx: fd=%d error %d: %s", fd, errno, strerror(errno));
+            D("readx: fd=%d error %d: %s", fd.get(), errno, strerror(errno));
             return false;
         } else {
-            D("readx: fd=%d disconnected", fd);
+            D("readx: fd=%d disconnected", fd.get());
             errno = 0;
             return false;
         }
     }
 
-    VLOG(RWX) << "readx: fd=" << fd << " wanted=" << len0 << " got=" << (len0 - len)
-              << " " << dump_hex(reinterpret_cast<const unsigned char*>(buf), len0);
+    VLOG(RWX) << "readx: fd=" << fd.get() << " wanted=" << len0 << " got=" << (len0 - len) << " "
+              << dump_hex(reinterpret_cast<const unsigned char*>(buf), len0);
 
     return true;
 }
 
-bool WriteFdExactly(int fd, const void* buf, size_t len) {
+bool WriteFdExactly(borrowed_fd fd, const void* buf, size_t len) {
     const char* p = reinterpret_cast<const char*>(buf);
     int r;
 
-    VLOG(RWX) << "writex: fd=" << fd << " len=" << len
-              << " " << dump_hex(reinterpret_cast<const unsigned char*>(buf), len);
+    VLOG(RWX) << "writex: fd=" << fd.get() << " len=" << len << " "
+              << dump_hex(reinterpret_cast<const unsigned char*>(buf), len);
 
     while (len > 0) {
         r = adb_write(fd, p, len);
         if (r == -1) {
-            D("writex: fd=%d error %d: %s", fd, errno, strerror(errno));
+            D("writex: fd=%d error %d: %s", fd.get(), errno, strerror(errno));
             if (errno == EAGAIN) {
                 std::this_thread::yield();
                 continue;
             } else if (errno == EPIPE) {
-                D("writex: fd=%d disconnected", fd);
+                D("writex: fd=%d disconnected", fd.get());
                 errno = 0;
                 return false;
             } else {
@@ -129,15 +129,15 @@
     return true;
 }
 
-bool WriteFdExactly(int fd, const char* str) {
+bool WriteFdExactly(borrowed_fd fd, const char* str) {
     return WriteFdExactly(fd, str, strlen(str));
 }
 
-bool WriteFdExactly(int fd, const std::string& str) {
+bool WriteFdExactly(borrowed_fd fd, const std::string& str) {
     return WriteFdExactly(fd, str.c_str(), str.size());
 }
 
-bool WriteFdFmt(int fd, const char* fmt, ...) {
+bool WriteFdFmt(borrowed_fd fd, const char* fmt, ...) {
     std::string str;
 
     va_list ap;
@@ -148,7 +148,7 @@
     return WriteFdExactly(fd, str);
 }
 
-bool ReadOrderlyShutdown(int fd) {
+bool ReadOrderlyShutdown(borrowed_fd fd) {
     char buf[16];
 
     // Only call this function if you're sure that the peer does
@@ -178,7 +178,7 @@
         // data. We don't repeatedly call adb_read() until we get zero because
         // we don't know how long that would take, but we do know that the
         // caller wants to close the socket soon.
-        VLOG(RWX) << "ReadOrderlyShutdown(" << fd << ") unexpectedly read "
+        VLOG(RWX) << "ReadOrderlyShutdown(" << fd.get() << ") unexpectedly read "
                   << dump_hex(buf, result);
         // Shutdown the socket to prevent the caller from reading or writing to
         // it which doesn't make sense if we just read and discarded some data.
diff --git a/adb/adb_io.h b/adb/adb_io.h
index d6e65d8..9628946 100644
--- a/adb/adb_io.h
+++ b/adb/adb_io.h
@@ -25,16 +25,16 @@
 #include "adb_unique_fd.h"
 
 // Sends the protocol "OKAY" message.
-bool SendOkay(int fd);
+bool SendOkay(borrowed_fd fd);
 
 // Sends the protocol "FAIL" message, with the given failure reason.
-bool SendFail(int fd, std::string_view reason);
+bool SendFail(borrowed_fd fd, std::string_view reason);
 
 // Writes a protocol-format string; a four hex digit length followed by the string data.
-bool SendProtocolString(int fd, std::string_view s);
+bool SendProtocolString(borrowed_fd fd, std::string_view s);
 
 // Reads a protocol-format string; a four hex digit length followed by the string data.
-bool ReadProtocolString(int fd, std::string* s, std::string* error);
+bool ReadProtocolString(borrowed_fd fd, std::string* s, std::string* error);
 
 // Reads exactly len bytes from fd into buf.
 //
@@ -42,7 +42,7 @@
 // were read. If EOF was found, errno will be set to 0.
 //
 // If this function fails, the contents of buf are undefined.
-bool ReadFdExactly(int fd, void* buf, size_t len);
+bool ReadFdExactly(borrowed_fd fd, void* buf, size_t len);
 
 // Given a client socket, wait for orderly/graceful shutdown. Call this:
 //
@@ -60,19 +60,19 @@
 // connect()s from the client to fail with WSAEADDRINUSE on Windows.
 // Returns true if it is sure that orderly/graceful shutdown has occurred with
 // no additional data read from the server.
-bool ReadOrderlyShutdown(int fd);
+bool ReadOrderlyShutdown(borrowed_fd fd);
 
 // Writes exactly len bytes from buf to fd.
 //
 // Returns false if there is an error or if the fd was closed before the write
 // completed. If the other end of the fd (such as in a socket, pipe, or fifo),
 // is closed, errno will be set to 0.
-bool WriteFdExactly(int fd, const void* buf, size_t len);
+bool WriteFdExactly(borrowed_fd fd, const void* buf, size_t len);
 
 // Same as above, but for strings.
-bool WriteFdExactly(int fd, const char* s);
-bool WriteFdExactly(int fd, const std::string& s);
+bool WriteFdExactly(borrowed_fd fd, const char* s);
+bool WriteFdExactly(borrowed_fd fd, const std::string& s);
 
 // Same as above, but formats the string to send.
-bool WriteFdFmt(int fd, const char* fmt, ...) __attribute__((__format__(__printf__, 2, 3)));
+bool WriteFdFmt(borrowed_fd fd, const char* fmt, ...) __attribute__((__format__(__printf__, 2, 3)));
 #endif /* ADB_IO_H */
diff --git a/adb/adb_unique_fd.h b/adb/adb_unique_fd.h
index d47213d..b6c910a 100644
--- a/adb/adb_unique_fd.h
+++ b/adb/adb_unique_fd.h
@@ -32,6 +32,8 @@
 using unique_fd = android::base::unique_fd;
 #endif
 
+using android::base::borrowed_fd;
+
 template <typename T>
 int adb_close(const android::base::unique_fd_impl<T>&)
         __attribute__((__unavailable__("adb_close called on unique_fd")));
diff --git a/adb/adb_utils.cpp b/adb/adb_utils.cpp
index 9791769..cf5fbc8 100644
--- a/adb/adb_utils.cpp
+++ b/adb/adb_utils.cpp
@@ -234,15 +234,15 @@
 
 #if !defined(_WIN32)
 // Windows version provided in sysdeps_win32.cpp
-bool set_file_block_mode(int fd, bool block) {
-    int flags = fcntl(fd, F_GETFL, 0);
+bool set_file_block_mode(borrowed_fd fd, bool block) {
+    int flags = fcntl(fd.get(), F_GETFL, 0);
     if (flags == -1) {
-        PLOG(ERROR) << "failed to fcntl(F_GETFL) for fd " << fd;
+        PLOG(ERROR) << "failed to fcntl(F_GETFL) for fd " << fd.get();
         return false;
     }
     flags = block ? (flags & ~O_NONBLOCK) : (flags | O_NONBLOCK);
-    if (fcntl(fd, F_SETFL, flags) != 0) {
-        PLOG(ERROR) << "failed to fcntl(F_SETFL) for fd " << fd << ", flags " << flags;
+    if (fcntl(fd.get(), F_SETFL, flags) != 0) {
+        PLOG(ERROR) << "failed to fcntl(F_SETFL) for fd " << fd.get() << ", flags " << flags;
         return false;
     }
     return true;
diff --git a/adb/adb_utils.h b/adb/adb_utils.h
index 8b0dcee..faad03d 100644
--- a/adb/adb_utils.h
+++ b/adb/adb_utils.h
@@ -26,6 +26,7 @@
 #include <android-base/macros.h>
 
 #include "adb.h"
+#include "adb_unique_fd.h"
 
 void close_stdin();
 
@@ -51,7 +52,7 @@
 [[noreturn]] void error_exit(const char* fmt, ...) __attribute__((__format__(__printf__, 1, 2)));
 [[noreturn]] void perror_exit(const char* fmt, ...) __attribute__((__format__(__printf__, 1, 2)));
 
-bool set_file_block_mode(int fd, bool block);
+bool set_file_block_mode(borrowed_fd fd, bool block);
 
 // Given forward/reverse targets, returns true if they look sane. If an error is found, fills
 // |error| and returns false.
diff --git a/adb/adb_utils_test.cpp b/adb/adb_utils_test.cpp
index bd676c2..cdca3aa 100644
--- a/adb/adb_utils_test.cpp
+++ b/adb/adb_utils_test.cpp
@@ -149,13 +149,13 @@
 TEST(adb_utils, set_file_block_mode) {
     unique_fd fd(adb_open("/dev/null", O_RDWR | O_APPEND));
     ASSERT_GE(fd, 0);
-    int flags = fcntl(fd, F_GETFL, 0);
+    int flags = fcntl(fd.get(), F_GETFL, 0);
     ASSERT_EQ(O_RDWR | O_APPEND, (flags & (O_RDWR | O_APPEND)));
     ASSERT_TRUE(set_file_block_mode(fd, false));
-    int new_flags = fcntl(fd, F_GETFL, 0);
+    int new_flags = fcntl(fd.get(), F_GETFL, 0);
     ASSERT_EQ(flags | O_NONBLOCK, new_flags);
     ASSERT_TRUE(set_file_block_mode(fd, true));
-    new_flags = fcntl(fd, F_GETFL, 0);
+    new_flags = fcntl(fd.get(), F_GETFL, 0);
     ASSERT_EQ(flags, new_flags);
 }
 #endif
diff --git a/adb/client/adb_client.cpp b/adb/client/adb_client.cpp
index 5a7bc8d..7e408a8 100644
--- a/adb/client/adb_client.cpp
+++ b/adb/client/adb_client.cpp
@@ -128,7 +128,7 @@
     return result;
 }
 
-bool adb_status(int fd, std::string* error) {
+bool adb_status(borrowed_fd fd, std::string* error) {
     char buf[5];
     if (!ReadFdExactly(fd, buf, 4)) {
         *error = perror_str("protocol fault (couldn't read status)");
diff --git a/adb/client/adb_client.h b/adb/client/adb_client.h
index 8d32c93..fe1e584 100644
--- a/adb/client/adb_client.h
+++ b/adb/client/adb_client.h
@@ -16,13 +16,14 @@
 
 #pragma once
 
-#include "adb.h"
-#include "sysdeps.h"
-#include "transport.h"
-
 #include <optional>
 #include <string>
 
+#include "adb.h"
+#include "adb_unique_fd.h"
+#include "sysdeps.h"
+#include "transport.h"
+
 // Explicitly check the adb server version.
 // All of the commands below do this implicitly.
 // Only the first invocation of this function will check the server version.
@@ -64,7 +65,7 @@
 
 // Reads a standard adb status response (OKAY|FAIL) and returns true in the
 // event of OKAY, false in the event of FAIL or protocol error.
-bool adb_status(int fd, std::string* _Nonnull error);
+bool adb_status(borrowed_fd fd, std::string* _Nonnull error);
 
 // Create a host command corresponding to selected transport type/serial.
 std::string format_host_command(const char* _Nonnull command);
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index f39aa58..728e5c1 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -170,9 +170,6 @@
         "     remove this app package from the device\n"
         "     '-k': keep the data and cache directories\n"
         "\n"
-        "backup/restore:\n"
-        "   to show usage run \"adb shell bu help\"\n"
-        "\n"
         "debugging:\n"
         " bugreport [PATH]\n"
         "     write bugreport to given PATH [default=bugreport.zip];\n"
@@ -262,7 +259,7 @@
 // stdout/stderr are routed independently and the remote exit code will be
 // returned.
 // if |callback| is non-null, stdout/stderr output will be handled by it.
-int read_and_dump(int fd, bool use_shell_protocol = false,
+int read_and_dump(borrowed_fd fd, bool use_shell_protocol = false,
                   StandardStreamsCallbackInterface* callback = &DEFAULT_STANDARD_STREAMS_CALLBACK) {
     int exit_code = 0;
     if (fd < 0) return exit_code;
@@ -305,9 +302,9 @@
             }
             length = protocol->data_length();
         } else {
-            D("read_and_dump(): pre adb_read(fd=%d)", fd);
+            D("read_and_dump(): pre adb_read(fd=%d)", fd.get());
             length = adb_read(fd, raw_buffer, sizeof(raw_buffer));
-            D("read_and_dump(): post adb_read(fd=%d): length=%d", fd, length);
+            D("read_and_dump(): post adb_read(fd=%d): length=%d", fd.get(), length);
             if (length <= 0) {
                 break;
             }
@@ -887,7 +884,7 @@
             return -1;
         }
         fprintf(stderr, "adb: trying pre-KitKat sideload method...\n");
-        return adb_sideload_legacy(filename, package_fd, static_cast<int>(sb.st_size));
+        return adb_sideload_legacy(filename, package_fd.get(), static_cast<int>(sb.st_size));
     }
 
     int opt = SIDELOAD_HOST_BLOCK_SIZE;
@@ -1207,14 +1204,14 @@
     return send_shell_command(cmd);
 }
 
-static void write_zeros(int bytes, int fd) {
+static void write_zeros(int bytes, borrowed_fd fd) {
     int old_stdin_mode = -1;
     int old_stdout_mode = -1;
     std::vector<char> buf(bytes);
 
-    D("write_zeros(%d) -> %d", bytes, fd);
+    D("write_zeros(%d) -> %d", bytes, fd.get());
 
-    stdinout_raw_prologue(-1, fd, old_stdin_mode, old_stdout_mode);
+    stdinout_raw_prologue(-1, fd.get(), old_stdin_mode, old_stdout_mode);
 
     if (fd == STDOUT_FILENO) {
         fwrite(buf.data(), 1, bytes, stdout);
@@ -1223,12 +1220,14 @@
         adb_write(fd, buf.data(), bytes);
     }
 
-    stdinout_raw_prologue(-1, fd, old_stdin_mode, old_stdout_mode);
+    stdinout_raw_prologue(-1, fd.get(), old_stdin_mode, old_stdout_mode);
 
     D("write_zeros() finished");
 }
 
 static int backup(int argc, const char** argv) {
+    fprintf(stdout, "WARNING: adb backup is deprecated and may be removed in a future release\n");
+
     const char* filename = "backup.ab";
 
     /* find, extract, and use any -f argument */
@@ -1278,6 +1277,8 @@
 }
 
 static int restore(int argc, const char** argv) {
+    fprintf(stdout, "WARNING: adb restore is deprecated and may be removed in a future release\n");
+
     if (argc != 2) error_exit("restore requires an argument");
 
     const char* filename = argv[1];
diff --git a/adb/client/console.cpp b/adb/client/console.cpp
index 1dbb6e2..d10f4de 100644
--- a/adb/client/console.cpp
+++ b/adb/client/console.cpp
@@ -71,7 +71,7 @@
         return -1;
     }
 
-    int port;
+    int port = -1;
     size_t emulator_count = 0;
     for (const auto& device : android::base::Split(devices, "\n")) {
         if (sscanf(device.c_str(), "emulator-%d", &port) == 1) {
diff --git a/adb/daemon/abb.cpp b/adb/daemon/abb.cpp
index aa75bb1..425438e 100644
--- a/adb/daemon/abb.cpp
+++ b/adb/daemon/abb.cpp
@@ -29,11 +29,11 @@
 
 class AdbFdTextOutput : public android::TextOutput {
   public:
-    explicit AdbFdTextOutput(int fd) : mFD(fd) {}
+    explicit AdbFdTextOutput(borrowed_fd fd) : fd_(fd) {}
 
   private:
     android::status_t print(const char* txt, size_t len) override {
-        return WriteFdExactly(mFD, txt, len) ? android::OK : -errno;
+        return WriteFdExactly(fd_, txt, len) ? android::OK : -errno;
     }
     void moveIndent(int delta) override { /*not implemented*/
     }
@@ -44,7 +44,7 @@
     }
 
   private:
-    int mFD;
+    borrowed_fd fd_;
 };
 
 std::vector<std::string_view> parseCmdArgs(std::string_view args) {
@@ -68,10 +68,11 @@
 
 }  // namespace
 
-static int execCmd(std::string_view args, int in, int out, int err) {
+static int execCmd(std::string_view args, borrowed_fd in, borrowed_fd out, borrowed_fd err) {
     AdbFdTextOutput oin(out);
     AdbFdTextOutput oerr(err);
-    return cmdMain(parseCmdArgs(args), oin, oerr, in, out, err, RunMode::kLibrary);
+    return cmdMain(parseCmdArgs(args), oin, oerr, in.get(), out.get(), err.get(),
+                   RunMode::kLibrary);
 }
 
 int main(int argc, char* const argv[]) {
diff --git a/adb/daemon/jdwp_service.cpp b/adb/daemon/jdwp_service.cpp
index 66bfc0d..cd9b669 100644
--- a/adb/daemon/jdwp_service.cpp
+++ b/adb/daemon/jdwp_service.cpp
@@ -325,12 +325,12 @@
 
     addrlen = pathlen + sizeof(addr.sun_family);
 
-    if (bind(s, reinterpret_cast<sockaddr*>(&addr), addrlen) < 0) {
+    if (bind(s.get(), reinterpret_cast<sockaddr*>(&addr), addrlen) < 0) {
         D("could not bind vm debug control socket: %d: %s", errno, strerror(errno));
         return -1;
     }
 
-    if (listen(s, 4) < 0) {
+    if (listen(s.get(), 4) < 0) {
         D("listen failed in jdwp control socket: %d: %s", errno, strerror(errno));
         return -1;
     }
diff --git a/adb/daemon/reboot_service.cpp b/adb/daemon/reboot_service.cpp
index a5a11b8..13398af 100644
--- a/adb/daemon/reboot_service.cpp
+++ b/adb/daemon/reboot_service.cpp
@@ -58,7 +58,7 @@
 
         sockaddr_un addr = {.sun_family = AF_UNIX};
         strncpy(addr.sun_path, "/dev/socket/recovery", sizeof(addr.sun_path) - 1);
-        if (connect(sock, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) == -1) {
+        if (connect(sock.get(), reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) == -1) {
             WriteFdFmt(fd, "reboot (%s) connect\n", strerror(errno));
             PLOG(ERROR) << "Couldn't connect to recovery socket";
             return;
diff --git a/adb/daemon/set_verity_enable_state_service.cpp b/adb/daemon/set_verity_enable_state_service.cpp
index 49dce66..4fbccdb 100644
--- a/adb/daemon/set_verity_enable_state_service.cpp
+++ b/adb/daemon/set_verity_enable_state_service.cpp
@@ -58,7 +58,7 @@
     }
 
     int OFF = 0;
-    bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
+    bool result = (ioctl(fd.get(), BLKROSET, &OFF) != -1);
     return result;
 }
 
@@ -197,7 +197,7 @@
         }
 
         if (!android::base::GetBoolProperty("ro.secure", false)) {
-            overlayfs_setup(fd, enable);
+            overlayfs_setup(fd.get(), enable);
             WriteFdExactly(fd.get(), "verity not enabled - ENG build\n");
             return;
         }
@@ -242,7 +242,7 @@
             }
         }
     }
-    if (!any_changed) any_changed = overlayfs_setup(fd, enable);
+    if (!any_changed) any_changed = overlayfs_setup(fd.get(), enable);
 
     if (any_changed) {
         WriteFdExactly(fd.get(), "Now reboot your device for settings to take effect\n");
diff --git a/adb/daemon/shell_service.cpp b/adb/daemon/shell_service.cpp
index 3c8f393..de97068 100644
--- a/adb/daemon/shell_service.cpp
+++ b/adb/daemon/shell_service.cpp
@@ -114,7 +114,7 @@
 namespace {
 
 // Reads from |fd| until close or failure.
-std::string ReadAll(int fd) {
+std::string ReadAll(borrowed_fd fd) {
     char buffer[512];
     std::string received;
 
@@ -317,9 +317,10 @@
             child_stdinout_sfd.reset(OpenPtyChildFd(pts_name, &child_error_sfd));
         }
 
-        dup2(child_stdinout_sfd, STDIN_FILENO);
-        dup2(child_stdinout_sfd, STDOUT_FILENO);
-        dup2(child_stderr_sfd != -1 ? child_stderr_sfd : child_stdinout_sfd, STDERR_FILENO);
+        dup2(child_stdinout_sfd.get(), STDIN_FILENO);
+        dup2(child_stdinout_sfd.get(), STDOUT_FILENO);
+        dup2(child_stderr_sfd != -1 ? child_stderr_sfd.get() : child_stdinout_sfd.get(),
+             STDERR_FILENO);
 
         // exec doesn't trigger destructors, close the FDs manually.
         stdinout_sfd_.reset(-1);
@@ -415,7 +416,7 @@
         }
     } else {
         // Raw protocol doesn't support multiple output streams, so combine stdout and stderr.
-        child_stderr_sfd.reset(dup(child_stdinout_sfd));
+        child_stderr_sfd.reset(dup(child_stdinout_sfd.get()));
     }
 
     D("execinprocess: stdin/stdout FD = %d, stderr FD = %d", stdinout_sfd_.get(),
@@ -537,7 +538,7 @@
     FD_ZERO(&master_write_set);
     for (unique_fd* sfd : {&protocol_sfd_, &stdinout_sfd_, &stderr_sfd_}) {
         if (*sfd != -1) {
-            FD_SET(*sfd, &master_read_set);
+            FD_SET(sfd->get(), &master_read_set);
         }
     }
 
@@ -547,8 +548,8 @@
         unique_fd* dead_sfd = SelectLoop(&master_read_set, &master_write_set);
         if (dead_sfd) {
             D("closing FD %d", dead_sfd->get());
-            FD_CLR(*dead_sfd, &master_read_set);
-            FD_CLR(*dead_sfd, &master_write_set);
+            FD_CLR(dead_sfd->get(), &master_read_set);
+            FD_CLR(dead_sfd->get(), &master_write_set);
             if (dead_sfd == &protocol_sfd_) {
                 // Using SIGHUP is a decent general way to indicate that the
                 // controlling process is going away. If specific signals are
@@ -573,7 +574,7 @@
 namespace {
 
 inline bool ValidAndInSet(const unique_fd& sfd, fd_set* set) {
-    return sfd != -1 && FD_ISSET(sfd, set);
+    return sfd != -1 && FD_ISSET(sfd.get(), set);
 }
 
 }   // namespace
@@ -581,7 +582,8 @@
 unique_fd* Subprocess::SelectLoop(fd_set* master_read_set_ptr,
                                   fd_set* master_write_set_ptr) {
     fd_set read_set, write_set;
-    int select_n = std::max(std::max(protocol_sfd_, stdinout_sfd_), stderr_sfd_) + 1;
+    int select_n =
+            std::max(std::max(protocol_sfd_.get(), stdinout_sfd_.get()), stderr_sfd_.get()) + 1;
     unique_fd* dead_sfd = nullptr;
 
     // Keep calling select() and passing data until an FD closes/errors.
@@ -614,8 +616,8 @@
             dead_sfd = PassInput();
             // If we didn't finish writing, block on stdin write.
             if (input_bytes_left_) {
-                FD_CLR(protocol_sfd_, master_read_set_ptr);
-                FD_SET(stdinout_sfd_, master_write_set_ptr);
+                FD_CLR(protocol_sfd_.get(), master_read_set_ptr);
+                FD_SET(stdinout_sfd_.get(), master_write_set_ptr);
             }
         }
 
@@ -624,8 +626,8 @@
             dead_sfd = PassInput();
             // If we finished writing, go back to blocking on protocol read.
             if (!input_bytes_left_) {
-                FD_SET(protocol_sfd_, master_read_set_ptr);
-                FD_CLR(stdinout_sfd_, master_write_set_ptr);
+                FD_SET(protocol_sfd_.get(), master_read_set_ptr);
+                FD_CLR(stdinout_sfd_.get(), master_write_set_ptr);
             }
         }
     }  // while (!dead_sfd)
@@ -639,7 +641,7 @@
         if (!input_->Read()) {
             // Read() uses ReadFdExactly() which sets errno to 0 on EOF.
             if (errno != 0) {
-                PLOG(ERROR) << "error reading protocol FD " << protocol_sfd_;
+                PLOG(ERROR) << "error reading protocol FD " << protocol_sfd_.get();
             }
             return &protocol_sfd_;
         }
@@ -655,7 +657,7 @@
                         ws.ws_col = cols;
                         ws.ws_xpixel = x_pixels;
                         ws.ws_ypixel = y_pixels;
-                        ioctl(stdinout_sfd_, TIOCSWINSZ, &ws);
+                        ioctl(stdinout_sfd_.get(), TIOCSWINSZ, &ws);
                     }
                     break;
                 case ShellProtocol::kIdStdin:
@@ -666,8 +668,7 @@
                         if (adb_shutdown(stdinout_sfd_, SHUT_WR) == 0) {
                             return nullptr;
                         }
-                        PLOG(ERROR) << "failed to shutdown writes to FD "
-                                    << stdinout_sfd_;
+                        PLOG(ERROR) << "failed to shutdown writes to FD " << stdinout_sfd_.get();
                         return &stdinout_sfd_;
                     } else {
                         // PTYs can't close just input, so rather than close the
@@ -688,7 +689,7 @@
         int bytes = adb_write(stdinout_sfd_, input_->data() + index, input_bytes_left_);
         if (bytes == 0 || (bytes < 0 && errno != EAGAIN)) {
             if (bytes < 0) {
-                PLOG(ERROR) << "error reading stdin FD " << stdinout_sfd_;
+                PLOG(ERROR) << "error reading stdin FD " << stdinout_sfd_.get();
             }
             // stdin is done, mark this packet as finished and we'll just start
             // dumping any further data received from the protocol FD.
@@ -708,14 +709,14 @@
         // read() returns EIO if a PTY closes; don't report this as an error,
         // it just means the subprocess completed.
         if (bytes < 0 && !(type_ == SubprocessType::kPty && errno == EIO)) {
-            PLOG(ERROR) << "error reading output FD " << *sfd;
+            PLOG(ERROR) << "error reading output FD " << sfd->get();
         }
         return sfd;
     }
 
     if (bytes > 0 && !output_->Write(id, bytes)) {
         if (errno != 0) {
-            PLOG(ERROR) << "error reading protocol FD " << protocol_sfd_;
+            PLOG(ERROR) << "error reading protocol FD " << protocol_sfd_.get();
         }
         return &protocol_sfd_;
     }
diff --git a/adb/daemon/shell_service.h b/adb/daemon/shell_service.h
index 3abd958..030228c 100644
--- a/adb/daemon/shell_service.h
+++ b/adb/daemon/shell_service.h
@@ -48,7 +48,7 @@
 // Sets up in/out and error streams to emulate shell-like behavior.
 //
 // Returns an open FD connected to the thread or -1 on failure.
-using Command = int(std::string_view args, int in, int out, int err);
+using Command = int(std::string_view args, borrowed_fd in, borrowed_fd out, borrowed_fd err);
 unique_fd StartCommandInProcess(std::string name, Command command, SubprocessProtocol protocol);
 
 // Create a pipe containing the error.
diff --git a/adb/daemon/shell_service_test.cpp b/adb/daemon/shell_service_test.cpp
index dc79d12..cdd8dbe 100644
--- a/adb/daemon/shell_service_test.cpp
+++ b/adb/daemon/shell_service_test.cpp
@@ -77,7 +77,7 @@
 namespace {
 
 // Reads raw data from |fd| until it closes or errors.
-std::string ReadRaw(int fd) {
+std::string ReadRaw(borrowed_fd fd) {
     char buffer[1024];
     char *cur_ptr = buffer, *end_ptr = buffer + sizeof(buffer);
 
@@ -93,12 +93,12 @@
 // Reads shell protocol data from |fd| until it closes or errors. Fills
 // |stdout| and |stderr| with their respective data, and returns the exit code
 // read from the protocol or -1 if an exit code packet was not received.
-int ReadShellProtocol(int fd, std::string* stdout, std::string* stderr) {
+int ReadShellProtocol(borrowed_fd fd, std::string* stdout, std::string* stderr) {
     int exit_code = -1;
     stdout->clear();
     stderr->clear();
 
-    auto protocol = std::make_unique<ShellProtocol>(fd);
+    auto protocol = std::make_unique<ShellProtocol>(fd.get());
     while (protocol->Read()) {
         switch (protocol->id()) {
             case ShellProtocol::kIdStdout:
diff --git a/adb/daemon/usb.cpp b/adb/daemon/usb.cpp
index 0a116ab..96ee6b2 100644
--- a/adb/daemon/usb.cpp
+++ b/adb/daemon/usb.cpp
@@ -119,7 +119,7 @@
 
 struct IoBlock {
     bool pending = false;
-    struct iocb control;
+    struct iocb control = {};
     std::shared_ptr<Block> payload;
 
     TransferId id() const { return TransferId::from_value(control.aio_data); }
@@ -297,9 +297,15 @@
                 }
 
                 struct usb_functionfs_event event;
-                if (TEMP_FAILURE_RETRY(adb_read(control_fd_.get(), &event, sizeof(event))) !=
-                    sizeof(event)) {
+                rc = TEMP_FAILURE_RETRY(adb_read(control_fd_.get(), &event, sizeof(event)));
+                if (rc == -1) {
                     PLOG(FATAL) << "failed to read functionfs event";
+                } else if (rc == 0) {
+                    LOG(WARNING) << "hit EOF on functionfs control fd";
+                    break;
+                } else if (rc != sizeof(event)) {
+                    LOG(FATAL) << "read functionfs event of unexpected size, expected "
+                               << sizeof(event) << ", got " << rc;
                 }
 
                 LOG(INFO) << "USB event: "
diff --git a/adb/fastdeploy/deployagent/deployagent.sh b/adb/fastdeploy/deployagent/deployagent.sh
index 4f17eb7..91576ca 100755
--- a/adb/fastdeploy/deployagent/deployagent.sh
+++ b/adb/fastdeploy/deployagent/deployagent.sh
@@ -1,7 +1,4 @@
-# Script to start "deployagent" on the device, which has a very rudimentary
-# shell.
-#
+#!/system/bin/sh
 base=/data/local/tmp
 export CLASSPATH=$base/deployagent.jar
 exec app_process $base com.android.fastdeploy.DeployAgent "$@"
-
diff --git a/adb/shell_protocol.h b/adb/shell_protocol.h
index 2c82689..4aab813 100644
--- a/adb/shell_protocol.h
+++ b/adb/shell_protocol.h
@@ -21,6 +21,7 @@
 #include <android-base/macros.h>
 
 #include "adb.h"
+#include "adb_unique_fd.h"
 
 // Class to send and receive shell protocol packets.
 //
@@ -60,7 +61,7 @@
     // should be dynamically allocated on the heap instead.
     //
     // |fd| is an open file descriptor to be used to send or receive packets.
-    explicit ShellProtocol(int fd);
+    explicit ShellProtocol(borrowed_fd fd);
     virtual ~ShellProtocol();
 
     // Returns a pointer to the data buffer.
@@ -103,7 +104,7 @@
         kHeaderSize = sizeof(Id) + sizeof(length_t)
     };
 
-    int fd_;
+    borrowed_fd fd_;
     char buffer_[kBufferSize];
     size_t data_length_ = 0, bytes_left_ = 0;
 
diff --git a/adb/shell_service_protocol.cpp b/adb/shell_service_protocol.cpp
index 13b66ec..95afaff 100644
--- a/adb/shell_service_protocol.cpp
+++ b/adb/shell_service_protocol.cpp
@@ -22,7 +22,7 @@
 
 #include "adb_io.h"
 
-ShellProtocol::ShellProtocol(int fd) : fd_(fd) {
+ShellProtocol::ShellProtocol(borrowed_fd fd) : fd_(fd) {
     buffer_[0] = kIdInvalid;
 }
 
diff --git a/adb/socket_spec.cpp b/adb/socket_spec.cpp
index de4fff9..1333724 100644
--- a/adb/socket_spec.cpp
+++ b/adb/socket_spec.cpp
@@ -314,14 +314,14 @@
         addr.svm_port = port == 0 ? VMADDR_PORT_ANY : port;
         addr.svm_cid = VMADDR_CID_ANY;
         socklen_t addr_len = sizeof(addr);
-        if (bind(serverfd, reinterpret_cast<struct sockaddr*>(&addr), addr_len)) {
+        if (bind(serverfd.get(), reinterpret_cast<struct sockaddr*>(&addr), addr_len)) {
             return -1;
         }
-        if (listen(serverfd, 4)) {
+        if (listen(serverfd.get(), 4)) {
             return -1;
         }
         if (serverfd >= 0 && resolved_port) {
-            if (getsockname(serverfd, reinterpret_cast<sockaddr*>(&addr), &addr_len) == 0) {
+            if (getsockname(serverfd.get(), reinterpret_cast<sockaddr*>(&addr), &addr_len) == 0) {
                 *resolved_port = addr.svm_port;
             } else {
                 return -1;
diff --git a/adb/sysdeps.h b/adb/sysdeps.h
index 15247e7..78abba5 100644
--- a/adb/sysdeps.h
+++ b/adb/sysdeps.h
@@ -36,6 +36,7 @@
 #include <android-base/unique_fd.h>
 #include <android-base/utf8.h>
 
+#include "adb_unique_fd.h"
 #include "sysdeps/errno.h"
 #include "sysdeps/network.h"
 #include "sysdeps/stat.h"
@@ -76,42 +77,40 @@
 
 extern int adb_thread_setname(const std::string& name);
 
-static __inline__ void  close_on_exec(int  fd)
-{
+static __inline__ void close_on_exec(borrowed_fd fd) {
     /* nothing really */
 }
 
-extern int  adb_unlink(const char*  path);
-#undef  unlink
-#define unlink  ___xxx_unlink
+extern int adb_unlink(const char* path);
+#undef unlink
+#define unlink ___xxx_unlink
 
 extern int adb_mkdir(const std::string& path, int mode);
-#undef   mkdir
-#define  mkdir  ___xxx_mkdir
+#undef mkdir
+#define mkdir ___xxx_mkdir
 
 // See the comments for the !defined(_WIN32) versions of adb_*().
 extern int adb_open(const char* path, int options);
 extern int adb_creat(const char* path, int mode);
-extern int adb_read(int fd, void* buf, int len);
-extern int adb_write(int fd, const void* buf, int len);
-extern int64_t adb_lseek(int fd, int64_t pos, int where);
-extern int adb_shutdown(int fd, int direction = SHUT_RDWR);
+extern int adb_read(borrowed_fd fd, void* buf, int len);
+extern int adb_write(borrowed_fd fd, const void* buf, int len);
+extern int64_t adb_lseek(borrowed_fd fd, int64_t pos, int where);
+extern int adb_shutdown(borrowed_fd fd, int direction = SHUT_RDWR);
 extern int adb_close(int fd);
 extern int adb_register_socket(SOCKET s);
 
 // See the comments for the !defined(_WIN32) version of unix_close().
-static __inline__ int  unix_close(int fd)
-{
+static __inline__ int unix_close(int fd) {
     return close(fd);
 }
-#undef   close
-#define  close   ____xxx_close
+#undef close
+#define close ____xxx_close
 
 // Like unix_read(), but may return EINTR.
-extern int  unix_read_interruptible(int  fd, void*  buf, size_t  len);
+extern int unix_read_interruptible(borrowed_fd fd, void* buf, size_t len);
 
 // See the comments for the !defined(_WIN32) version of unix_read().
-static __inline__ int unix_read(int fd, void* buf, size_t len) {
+static __inline__ int unix_read(borrowed_fd fd, void* buf, size_t len) {
     return TEMP_FAILURE_RETRY(unix_read_interruptible(fd, buf, len));
 }
 
@@ -119,23 +118,21 @@
 #define  read  ___xxx_read
 
 // See the comments for the !defined(_WIN32) version of unix_write().
-static __inline__  int  unix_write(int  fd, const void*  buf, size_t  len)
-{
-    return write(fd, buf, len);
+static __inline__ int unix_write(borrowed_fd fd, const void* buf, size_t len) {
+    return write(fd.get(), buf, len);
 }
 #undef   write
 #define  write  ___xxx_write
 
 // See the comments for the !defined(_WIN32) version of unix_lseek().
-static __inline__ int unix_lseek(int fd, int pos, int where) {
-    return lseek(fd, pos, where);
+static __inline__ int unix_lseek(borrowed_fd fd, int pos, int where) {
+    return lseek(fd.get(), pos, where);
 }
 #undef lseek
 #define lseek ___xxx_lseek
 
 // See the comments for the !defined(_WIN32) version of adb_open_mode().
-static __inline__ int  adb_open_mode(const char* path, int options, int mode)
-{
+static __inline__ int adb_open_mode(const char* path, int options, int mode) {
     return adb_open(path, options);
 }
 
@@ -152,7 +149,7 @@
 // with |fd| must have GENERIC_READ access (which console FDs have by default).
 // Returns 1 if |fd| is a console FD, 0 otherwise. The value of errno after
 // calling this function is unreliable and should not be used.
-int unix_isatty(int fd);
+int unix_isatty(borrowed_fd fd);
 #define  isatty  ___xxx_isatty
 
 int network_inaddr_any_server(int port, int type, std::string* error);
@@ -168,20 +165,21 @@
 int network_connect(const std::string& host, int port, int type, int timeout,
                     std::string* error);
 
-extern int  adb_socket_accept(int  serverfd, struct sockaddr*  addr, socklen_t  *addrlen);
+extern int adb_socket_accept(borrowed_fd serverfd, struct sockaddr* addr, socklen_t* addrlen);
 
 #undef   accept
 #define  accept  ___xxx_accept
 
 // Returns the local port number of a bound socket, or -1 on failure.
-int adb_socket_get_local_port(int fd);
+int adb_socket_get_local_port(borrowed_fd fd);
 
-extern int  adb_setsockopt(int  fd, int  level, int  optname, const void*  optval, socklen_t  optlen);
+extern int adb_setsockopt(borrowed_fd fd, int level, int optname, const void* optval,
+                          socklen_t optlen);
 
 #undef   setsockopt
 #define  setsockopt  ___xxx_setsockopt
 
-extern int  adb_socketpair( int  sv[2] );
+extern int adb_socketpair(int sv[2]);
 
 struct adb_pollfd {
     int fd;
@@ -214,8 +212,7 @@
 extern int adb_fputc(int ch, FILE* stream);
 extern int adb_putchar(int ch);
 extern int adb_puts(const char* buf);
-extern size_t adb_fwrite(const void* ptr, size_t size, size_t nmemb,
-                         FILE* stream);
+extern size_t adb_fwrite(const void* ptr, size_t size, size_t nmemb, FILE* stream);
 
 extern FILE* adb_fopen(const char* f, const char* m);
 
@@ -344,9 +341,8 @@
     return c == '/';
 }
 
-static __inline__ void  close_on_exec(int  fd)
-{
-    fcntl( fd, F_SETFD, FD_CLOEXEC );
+static __inline__ void close_on_exec(borrowed_fd fd) {
+    fcntl(fd.get(), F_SETFD, FD_CLOEXEC);
 }
 
 // Open a file and return a file descriptor that may be used with unix_read(),
@@ -374,12 +370,10 @@
 
 // Similar to the two-argument adb_open(), but takes a mode parameter for file
 // creation. See adb_open() for more info.
-static __inline__ int  adb_open_mode( const char*  pathname, int  options, int  mode )
-{
-    return TEMP_FAILURE_RETRY( open( pathname, options, mode ) );
+static __inline__ int adb_open_mode(const char* pathname, int options, int mode) {
+    return TEMP_FAILURE_RETRY(open(pathname, options, mode));
 }
 
-
 // Open a file and return a file descriptor that may be used with adb_read(),
 // adb_write(), adb_close(), but not unix_read(), unix_write(), unix_close().
 //
@@ -387,23 +381,21 @@
 // sysdeps_win32.cpp) uses Windows native file I/O and bypasses the C Runtime
 // and its CR/LF translation. The returned file descriptor should be used with
 // adb_read(), adb_write(), adb_close(), etc.
-static __inline__ int  adb_open( const char*  pathname, int  options )
-{
-    int  fd = TEMP_FAILURE_RETRY( open( pathname, options ) );
-    if (fd < 0)
-        return -1;
-    close_on_exec( fd );
+static __inline__ int adb_open(const char* pathname, int options) {
+    int fd = TEMP_FAILURE_RETRY(open(pathname, options));
+    if (fd < 0) return -1;
+    close_on_exec(fd);
     return fd;
 }
-#undef   open
-#define  open    ___xxx_open
+#undef open
+#define open ___xxx_open
 
-static __inline__ int adb_shutdown(int fd, int direction = SHUT_RDWR) {
-    return shutdown(fd, direction);
+static __inline__ int adb_shutdown(borrowed_fd fd, int direction = SHUT_RDWR) {
+    return shutdown(fd.get(), direction);
 }
 
-#undef   shutdown
-#define  shutdown   ____xxx_shutdown
+#undef shutdown
+#define shutdown ____xxx_shutdown
 
 // Closes a file descriptor that came from adb_open() or adb_open_mode(), but
 // not designed to take a file descriptor from unix_open(). See the comments
@@ -411,81 +403,76 @@
 __inline__ int adb_close(int fd) {
     return close(fd);
 }
-#undef   close
-#define  close   ____xxx_close
+#undef close
+#define close ____xxx_close
 
 // On Windows, ADB has an indirection layer for file descriptors. If we get a
 // Win32 SOCKET object from an external library, we have to map it in to that
 // indirection layer, which this does.
-__inline__ int  adb_register_socket(int s) {
+__inline__ int adb_register_socket(int s) {
     return s;
 }
 
-static __inline__  int  adb_read(int  fd, void*  buf, size_t  len)
-{
-    return TEMP_FAILURE_RETRY( read( fd, buf, len ) );
+static __inline__ int adb_read(borrowed_fd fd, void* buf, size_t len) {
+    return TEMP_FAILURE_RETRY(read(fd.get(), buf, len));
 }
 
 // Like unix_read(), but does not handle EINTR.
-static __inline__ int unix_read_interruptible(int fd, void* buf, size_t len) {
-    return read(fd, buf, len);
+static __inline__ int unix_read_interruptible(borrowed_fd fd, void* buf, size_t len) {
+    return read(fd.get(), buf, len);
 }
 
-#undef   read
-#define  read  ___xxx_read
+#undef read
+#define read ___xxx_read
 
-static __inline__  int  adb_write(int  fd, const void*  buf, size_t  len)
-{
-    return TEMP_FAILURE_RETRY( write( fd, buf, len ) );
+static __inline__ int adb_write(borrowed_fd fd, const void* buf, size_t len) {
+    return TEMP_FAILURE_RETRY(write(fd.get(), buf, len));
 }
 #undef   write
 #define  write  ___xxx_write
 
-static __inline__ int64_t adb_lseek(int fd, int64_t pos, int where) {
+static __inline__ int64_t adb_lseek(borrowed_fd fd, int64_t pos, int where) {
 #if defined(__APPLE__)
-    return lseek(fd, pos, where);
+    return lseek(fd.get(), pos, where);
 #else
-    return lseek64(fd, pos, where);
+    return lseek64(fd.get(), pos, where);
 #endif
 }
 #undef lseek
 #define lseek ___xxx_lseek
 
-static __inline__  int    adb_unlink(const char*  path)
-{
-    return  unlink(path);
+static __inline__ int adb_unlink(const char* path) {
+    return unlink(path);
 }
-#undef  unlink
-#define unlink  ___xxx_unlink
+#undef unlink
+#define unlink ___xxx_unlink
 
-static __inline__  int  adb_creat(const char*  path, int  mode)
-{
-    int  fd = TEMP_FAILURE_RETRY( creat( path, mode ) );
+static __inline__ int adb_creat(const char* path, int mode) {
+    int fd = TEMP_FAILURE_RETRY(creat(path, mode));
 
-    if ( fd < 0 )
-        return -1;
+    if (fd < 0) return -1;
 
     close_on_exec(fd);
     return fd;
 }
-#undef   creat
-#define  creat  ___xxx_creat
+#undef creat
+#define creat ___xxx_creat
 
-static __inline__ int unix_isatty(int fd) {
-    return isatty(fd);
+static __inline__ int unix_isatty(borrowed_fd fd) {
+    return isatty(fd.get());
 }
-#define  isatty  ___xxx_isatty
+#define isatty ___xxx_isatty
 
 // Helper for network_* functions.
 inline int _fd_set_error_str(int fd, std::string* error) {
-  if (fd == -1) {
-    *error = strerror(errno);
-  }
-  return fd;
+    if (fd == -1) {
+        *error = strerror(errno);
+    }
+    return fd;
 }
 
 inline int network_inaddr_any_server(int port, int type, std::string* error) {
-  return _fd_set_error_str(socket_inaddr_any_server(port, type), error);
+    return _fd_set_error_str(socket_inaddr_any_server(port, type), error);
 }
 
 inline int network_local_client(const char* name, int namespace_id, int type, std::string* error) {
@@ -498,22 +485,21 @@
 
 int network_connect(const std::string& host, int port, int type, int timeout, std::string* error);
 
-static __inline__ int  adb_socket_accept(int  serverfd, struct sockaddr*  addr, socklen_t  *addrlen)
-{
+static __inline__ int adb_socket_accept(borrowed_fd serverfd, struct sockaddr* addr,
+                                        socklen_t* addrlen) {
     int fd;
 
-    fd = TEMP_FAILURE_RETRY( accept( serverfd, addr, addrlen ) );
-    if (fd >= 0)
-        close_on_exec(fd);
+    fd = TEMP_FAILURE_RETRY(accept(serverfd.get(), addr, addrlen));
+    if (fd >= 0) close_on_exec(fd);
 
     return fd;
 }
 
-#undef   accept
-#define  accept  ___xxx_accept
+#undef accept
+#define accept ___xxx_accept
 
-inline int adb_socket_get_local_port(int fd) {
-    return socket_get_local_port(fd);
+inline int adb_socket_get_local_port(borrowed_fd fd) {
+    return socket_get_local_port(fd.get());
 }
 
 // Operate on a file descriptor returned from unix_open() or a well-known file
@@ -524,10 +510,10 @@
 // Windows implementations (in the ifdef above and in sysdeps_win32.cpp) call
 // into the C Runtime and its configurable CR/LF translation (which is settable
 // via _setmode()).
-#define  unix_read   adb_read
-#define  unix_write  adb_write
+#define unix_read adb_read
+#define unix_write adb_write
 #define unix_lseek adb_lseek
-#define  unix_close  adb_close
+#define unix_close adb_close
 
 static __inline__ int adb_thread_setname(const std::string& name) {
 #ifdef __APPLE__
@@ -542,34 +528,31 @@
 #endif
 }
 
-static __inline__ int  adb_setsockopt( int  fd, int  level, int  optname, const void*  optval, socklen_t  optlen )
-{
-    return setsockopt( fd, level, optname, optval, optlen );
+static __inline__ int adb_setsockopt(borrowed_fd fd, int level, int optname, const void* optval,
+                                     socklen_t optlen) {
+    return setsockopt(fd.get(), level, optname, optval, optlen);
 }
 
-#undef   setsockopt
-#define  setsockopt  ___xxx_setsockopt
+#undef setsockopt
+#define setsockopt ___xxx_setsockopt
 
-static __inline__ int  unix_socketpair( int  d, int  type, int  protocol, int sv[2] )
-{
-    return socketpair( d, type, protocol, sv );
+static __inline__ int unix_socketpair(int d, int type, int protocol, int sv[2]) {
+    return socketpair(d, type, protocol, sv);
 }
 
-static __inline__ int  adb_socketpair( int  sv[2] )
-{
-    int  rc;
+static __inline__ int adb_socketpair(int sv[2]) {
+    int rc;
 
-    rc = unix_socketpair( AF_UNIX, SOCK_STREAM, 0, sv );
-    if (rc < 0)
-        return -1;
+    rc = unix_socketpair(AF_UNIX, SOCK_STREAM, 0, sv);
+    if (rc < 0) return -1;
 
-    close_on_exec( sv[0] );
-    close_on_exec( sv[1] );
+    close_on_exec(sv[0]);
+    close_on_exec(sv[1]);
     return 0;
 }
 
-#undef   socketpair
-#define  socketpair   ___xxx_socketpair
+#undef socketpair
+#define socketpair ___xxx_socketpair
 
 typedef struct pollfd adb_pollfd;
 static __inline__ int adb_poll(adb_pollfd* fds, size_t nfds, int timeout) {
@@ -578,13 +561,12 @@
 
 #define poll ___xxx_poll
 
-static __inline__ int  adb_mkdir(const std::string& path, int mode)
-{
+static __inline__ int adb_mkdir(const std::string& path, int mode) {
     return mkdir(path.c_str(), mode);
 }
 
-#undef   mkdir
-#define  mkdir  ___xxx_mkdir
+#undef mkdir
+#define mkdir ___xxx_mkdir
 
 static __inline__ int adb_is_absolute_host_path(const char* path) {
     return path[0] == '/';
@@ -592,15 +574,15 @@
 
 #endif /* !_WIN32 */
 
-static inline void disable_tcp_nagle(int fd) {
+static inline void disable_tcp_nagle(borrowed_fd fd) {
     int off = 1;
-    adb_setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &off, sizeof(off));
+    adb_setsockopt(fd.get(), IPPROTO_TCP, TCP_NODELAY, &off, sizeof(off));
 }
 
 // Sets TCP socket |fd| to send a keepalive TCP message every |interval_sec| seconds. Set
 // |interval_sec| to 0 to disable keepalives. If keepalives are enabled, the connection will be
 // configured to drop after 10 missed keepalives. Returns true on success.
-bool set_tcp_keepalive(int fd, int interval_sec);
+bool set_tcp_keepalive(borrowed_fd fd, int interval_sec);
 
 #if defined(_WIN32)
 // Win32 defines ERROR, which we don't need, but which conflicts with google3 logging.
diff --git a/adb/sysdeps/posix/network.cpp b/adb/sysdeps/posix/network.cpp
index 4de240e..c5c2275 100644
--- a/adb/sysdeps/posix/network.cpp
+++ b/adb/sysdeps/posix/network.cpp
@@ -104,13 +104,13 @@
     socklen_t addrlen = sizeof(addr_storage);
     sockaddr* addr = (ipv6 ? loopback_addr6 : loopback_addr4)(&addr_storage, &addrlen, port);
 
-    if (bind(s, addr, addrlen) != 0) {
+    if (bind(s.get(), addr, addrlen) != 0) {
         set_error(error);
         return -1;
     }
 
     if (type == SOCK_STREAM || type == SOCK_SEQPACKET) {
-        if (listen(s, SOMAXCONN) != 0) {
+        if (listen(s.get(), SOMAXCONN) != 0) {
             set_error(error);
             return -1;
         }
diff --git a/adb/sysdeps/uio.h b/adb/sysdeps/uio.h
index d06ef89..ced884b 100644
--- a/adb/sysdeps/uio.h
+++ b/adb/sysdeps/uio.h
@@ -18,6 +18,8 @@
 
 #include <sys/types.h>
 
+#include "adb_unique_fd.h"
+
 #if defined(_WIN32)
 
 // Layout of this struct must match struct WSABUF (verified via static assert in sysdeps_win32.cpp)
@@ -26,13 +28,15 @@
     void* iov_base;
 };
 
-ssize_t adb_writev(int fd, const adb_iovec* iov, int iovcnt);
+ssize_t adb_writev(borrowed_fd fd, const adb_iovec* iov, int iovcnt);
 
 #else
 
 #include <sys/uio.h>
 using adb_iovec = struct iovec;
-#define adb_writev writev
+inline ssize_t adb_writev(borrowed_fd fd, const adb_iovec* iov, int iovcnt) {
+    return writev(fd.get(), iov, iovcnt);
+}
 
 #endif
 
diff --git a/adb/sysdeps_unix.cpp b/adb/sysdeps_unix.cpp
index 4445a44..3fdc917 100644
--- a/adb/sysdeps_unix.cpp
+++ b/adb/sysdeps_unix.cpp
@@ -16,7 +16,7 @@
 
 #include "sysdeps.h"
 
-bool set_tcp_keepalive(int fd, int interval_sec) {
+bool set_tcp_keepalive(borrowed_fd fd, int interval_sec) {
     int enable = (interval_sec > 0);
     if (adb_setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &enable, sizeof(enable))) {
         return false;
diff --git a/adb/sysdeps_win32.cpp b/adb/sysdeps_win32.cpp
index 4c5d8cb..886ded4 100644
--- a/adb/sysdeps_win32.cpp
+++ b/adb/sysdeps_win32.cpp
@@ -145,16 +145,14 @@
 static  FHRec        _win32_fhs[ WIN32_MAX_FHS ];
 static  int          _win32_fh_next;  // where to start search for free FHRec
 
-static FH
-_fh_from_int( int   fd, const char*   func )
-{
-    FH  f;
+static FH _fh_from_int(borrowed_fd bfd, const char* func) {
+    FH f;
 
+    int fd = bfd.get();
     fd -= WIN32_FH_BASE;
 
     if (fd < 0 || fd >= WIN32_MAX_FHS) {
-        D( "_fh_from_int: invalid fd %d passed to %s", fd + WIN32_FH_BASE,
-           func );
+        D("_fh_from_int: invalid fd %d passed to %s", fd + WIN32_FH_BASE, func);
         errno = EBADF;
         return nullptr;
     }
@@ -162,8 +160,7 @@
     f = &_win32_fhs[fd];
 
     if (f->used == 0) {
-        D( "_fh_from_int: invalid fd %d passed to %s", fd + WIN32_FH_BASE,
-           func );
+        D("_fh_from_int: invalid fd %d passed to %s", fd + WIN32_FH_BASE, func);
         errno = EBADF;
         return nullptr;
     }
@@ -171,20 +168,15 @@
     return f;
 }
 
-
-static int
-_fh_to_int( FH  f )
-{
+static int _fh_to_int(FH f) {
     if (f && f->used && f >= _win32_fhs && f < _win32_fhs + WIN32_MAX_FHS)
         return (int)(f - _win32_fhs) + WIN32_FH_BASE;
 
     return -1;
 }
 
-static FH
-_fh_alloc( FHClass  clazz )
-{
-    FH   f = nullptr;
+static FH _fh_alloc(FHClass clazz) {
+    FH f = nullptr;
 
     std::lock_guard<std::mutex> lock(_win32_lock);
 
@@ -206,10 +198,7 @@
     return nullptr;
 }
 
-
-static int
-_fh_close( FH   f )
-{
+static int _fh_close(FH f) {
     // Use lock so that closing only happens once and so that _fh_alloc can't
     // allocate a FH that we're in the middle of closing.
     std::lock_guard<std::mutex> lock(_win32_lock);
@@ -456,7 +445,7 @@
     return _fh_to_int(f);
 }
 
-int adb_read(int fd, void* buf, int len) {
+int adb_read(borrowed_fd fd, void* buf, int len) {
     FH f = _fh_from_int(fd, __func__);
 
     if (f == nullptr) {
@@ -467,7 +456,7 @@
     return f->clazz->_fh_read(f, buf, len);
 }
 
-int adb_write(int fd, const void* buf, int len) {
+int adb_write(borrowed_fd fd, const void* buf, int len) {
     FH f = _fh_from_int(fd, __func__);
 
     if (f == nullptr) {
@@ -478,7 +467,7 @@
     return f->clazz->_fh_write(f, buf, len);
 }
 
-ssize_t adb_writev(int fd, const adb_iovec* iov, int iovcnt) {
+ssize_t adb_writev(borrowed_fd fd, const adb_iovec* iov, int iovcnt) {
     FH f = _fh_from_int(fd, __func__);
 
     if (f == nullptr) {
@@ -489,7 +478,7 @@
     return f->clazz->_fh_writev(f, iov, iovcnt);
 }
 
-int64_t adb_lseek(int fd, int64_t pos, int where) {
+int64_t adb_lseek(borrowed_fd fd, int64_t pos, int where) {
     FH f = _fh_from_int(fd, __func__);
     if (!f) {
         errno = EBADF;
@@ -973,11 +962,11 @@
 }
 
 #undef accept
-int adb_socket_accept(int serverfd, struct sockaddr* addr, socklen_t* addrlen) {
+int adb_socket_accept(borrowed_fd serverfd, struct sockaddr* addr, socklen_t* addrlen) {
     FH serverfh = _fh_from_int(serverfd, __func__);
 
     if (!serverfh || serverfh->clazz != &_fh_socket_class) {
-        D("adb_socket_accept: invalid fd %d", serverfd);
+        D("adb_socket_accept: invalid fd %d", serverfd.get());
         errno = EBADF;
         return -1;
     }
@@ -992,7 +981,7 @@
     fh->fh_socket = accept(serverfh->fh_socket, addr, addrlen);
     if (fh->fh_socket == INVALID_SOCKET) {
         const DWORD err = WSAGetLastError();
-        LOG(ERROR) << "adb_socket_accept: accept on fd " << serverfd
+        LOG(ERROR) << "adb_socket_accept: accept on fd " << serverfd.get()
                    << " failed: " + android::base::SystemErrorCodeToString(err);
         _socket_set_errno(err);
         return -1;
@@ -1000,16 +989,16 @@
 
     const int fd = _fh_to_int(fh.get());
     snprintf(fh->name, sizeof(fh->name), "%d(accept:%s)", fd, serverfh->name);
-    D("adb_socket_accept on fd %d returns fd %d", serverfd, fd);
+    D("adb_socket_accept on fd %d returns fd %d", serverfd.get(), fd);
     fh.release();
     return fd;
 }
 
-int adb_setsockopt(int fd, int level, int optname, const void* optval, socklen_t optlen) {
+int adb_setsockopt(borrowed_fd fd, int level, int optname, const void* optval, socklen_t optlen) {
     FH fh = _fh_from_int(fd, __func__);
 
     if (!fh || fh->clazz != &_fh_socket_class) {
-        D("adb_setsockopt: invalid fd %d", fd);
+        D("adb_setsockopt: invalid fd %d", fd.get());
         errno = EBADF;
         return -1;
     }
@@ -1022,7 +1011,7 @@
         setsockopt(fh->fh_socket, level, optname, reinterpret_cast<const char*>(optval), optlen);
     if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
-        D("adb_setsockopt: setsockopt on fd %d level %d optname %d failed: %s\n", fd, level,
+        D("adb_setsockopt: setsockopt on fd %d level %d optname %d failed: %s\n", fd.get(), level,
           optname, android::base::SystemErrorCodeToString(err).c_str());
         _socket_set_errno(err);
         result = -1;
@@ -1030,11 +1019,11 @@
     return result;
 }
 
-int adb_getsockname(int fd, struct sockaddr* sockaddr, socklen_t* optlen) {
+static int adb_getsockname(borrowed_fd fd, struct sockaddr* sockaddr, socklen_t* optlen) {
     FH fh = _fh_from_int(fd, __func__);
 
     if (!fh || fh->clazz != &_fh_socket_class) {
-        D("adb_getsockname: invalid fd %d", fd);
+        D("adb_getsockname: invalid fd %d", fd.get());
         errno = EBADF;
         return -1;
     }
@@ -1042,7 +1031,7 @@
     int result = getsockname(fh->fh_socket, sockaddr, optlen);
     if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
-        D("adb_getsockname: setsockopt on fd %d failed: %s\n", fd,
+        D("adb_getsockname: setsockopt on fd %d failed: %s\n", fd.get(),
           android::base::SystemErrorCodeToString(err).c_str());
         _socket_set_errno(err);
         result = -1;
@@ -1050,7 +1039,7 @@
     return result;
 }
 
-int adb_socket_get_local_port(int fd) {
+int adb_socket_get_local_port(borrowed_fd fd) {
     sockaddr_storage addr_storage;
     socklen_t addr_len = sizeof(addr_storage);
 
@@ -1068,11 +1057,11 @@
     return ntohs(reinterpret_cast<sockaddr_in*>(&addr_storage)->sin_port);
 }
 
-int adb_shutdown(int fd, int direction) {
+int adb_shutdown(borrowed_fd fd, int direction) {
     FH f = _fh_from_int(fd, __func__);
 
     if (!f || f->clazz != &_fh_socket_class) {
-        D("adb_shutdown: invalid fd %d", fd);
+        D("adb_shutdown: invalid fd %d", fd.get());
         errno = EBADF;
         return -1;
     }
@@ -1080,7 +1069,7 @@
     D("adb_shutdown: %s", f->name);
     if (shutdown(f->fh_socket, direction) == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
-        D("socket shutdown fd %d failed: %s", fd,
+        D("socket shutdown fd %d failed: %s", fd.get(),
           android::base::SystemErrorCodeToString(err).c_str());
         _socket_set_errno(err);
         return -1;
@@ -1138,12 +1127,12 @@
     return -1;
 }
 
-bool set_file_block_mode(int fd, bool block) {
+bool set_file_block_mode(borrowed_fd fd, bool block) {
     FH fh = _fh_from_int(fd, __func__);
 
     if (!fh || !fh->used) {
         errno = EBADF;
-        D("Setting nonblocking on bad file descriptor %d", fd);
+        D("Setting nonblocking on bad file descriptor %d", fd.get());
         return false;
     }
 
@@ -1152,22 +1141,22 @@
         if (ioctlsocket(fh->u.socket, FIONBIO, &x) != 0) {
             int error = WSAGetLastError();
             _socket_set_errno(error);
-            D("Setting %d nonblocking failed (%d)", fd, error);
+            D("Setting %d nonblocking failed (%d)", fd.get(), error);
             return false;
         }
         return true;
     } else {
         errno = ENOTSOCK;
-        D("Setting nonblocking on non-socket %d", fd);
+        D("Setting nonblocking on non-socket %d", fd.get());
         return false;
     }
 }
 
-bool set_tcp_keepalive(int fd, int interval_sec) {
+bool set_tcp_keepalive(borrowed_fd fd, int interval_sec) {
     FH fh = _fh_from_int(fd, __func__);
 
     if (!fh || fh->clazz != &_fh_socket_class) {
-        D("set_tcp_keepalive(%d) failed: invalid fd", fd);
+        D("set_tcp_keepalive(%d) failed: invalid fd", fd.get());
         errno = EBADF;
         return false;
     }
@@ -1181,7 +1170,7 @@
     if (WSAIoctl(fh->fh_socket, SIO_KEEPALIVE_VALS, &keepalive, sizeof(keepalive), nullptr, 0,
                  &bytes_returned, nullptr, nullptr) != 0) {
         const DWORD err = WSAGetLastError();
-        D("set_tcp_keepalive(%d) failed: %s", fd,
+        D("set_tcp_keepalive(%d) failed: %s", fd.get(),
           android::base::SystemErrorCodeToString(err).c_str());
         _socket_set_errno(err);
         return false;
@@ -1228,12 +1217,12 @@
 // Returns a console HANDLE if |fd| is a console, otherwise returns nullptr.
 // If a valid HANDLE is returned and |mode| is not null, |mode| is also filled
 // with the console mode. Requires GENERIC_READ access to the underlying HANDLE.
-static HANDLE _get_console_handle(int fd, DWORD* mode=nullptr) {
+static HANDLE _get_console_handle(borrowed_fd fd, DWORD* mode = nullptr) {
     // First check isatty(); this is very fast and eliminates most non-console
     // FDs, but returns 1 for both consoles and character devices like NUL.
 #pragma push_macro("isatty")
 #undef isatty
-    if (!isatty(fd)) {
+    if (!isatty(fd.get())) {
         return nullptr;
     }
 #pragma pop_macro("isatty")
@@ -1241,7 +1230,7 @@
     // To differentiate between character devices and consoles we need to get
     // the underlying HANDLE and use GetConsoleMode(), which is what requires
     // GENERIC_READ permissions.
-    const intptr_t intptr_handle = _get_osfhandle(fd);
+    const intptr_t intptr_handle = _get_osfhandle(fd.get());
     if (intptr_handle == -1) {
         return nullptr;
     }
@@ -1265,7 +1254,7 @@
     return _get_console_handle(fd);
 }
 
-int unix_isatty(int fd) {
+int unix_isatty(borrowed_fd fd) {
     return _get_console_handle(fd) ? 1 : 0;
 }
 
@@ -1645,7 +1634,7 @@
 
 // Prefix the len bytes in buf with the escape character, and then return the
 // new buffer length.
-size_t _escape_prefix(char* const buf, const size_t len) {
+static size_t _escape_prefix(char* const buf, const size_t len) {
     // If nothing to prefix, don't do anything. We might be called with
     // len == 0, if alt was held down with a dead key which produced nothing.
     if (len == 0) {
@@ -2073,7 +2062,7 @@
 }
 
 // Called by 'adb shell' and 'adb exec-in' (via unix_read()) to read from stdin.
-int unix_read_interruptible(int fd, void* buf, size_t len) {
+int unix_read_interruptible(borrowed_fd fd, void* buf, size_t len) {
     if ((fd == STDIN_FILENO) && (_console_handle != nullptr)) {
         // If it is a request to read from stdin, and stdin_raw_init() has been
         // called, and it successfully configured the console, then read from
@@ -2093,7 +2082,7 @@
         // plain read() in favor of unix_read() or adb_read().
 #pragma push_macro("read")
 #undef read
-        return read(fd, buf, len);
+        return read(fd.get(), buf, len);
 #pragma pop_macro("read")
     }
 }
diff --git a/base/Android.bp b/base/Android.bp
index d4268ca..340f814 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -46,6 +46,7 @@
     name: "libbase_defaults",
     defaults: ["libbase_cflags_defaults"],
     srcs: [
+        "abi_compatibility.cpp",
         "chrono_utils.cpp",
         "cmsg.cpp",
         "file.cpp",
diff --git a/base/abi_compatibility.cpp b/base/abi_compatibility.cpp
new file mode 100644
index 0000000..06a7801
--- /dev/null
+++ b/base/abi_compatibility.cpp
@@ -0,0 +1,77 @@
+/*
+ * 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 <memory>
+
+#include "android-base/cmsg.h"
+#include "android-base/file.h"
+#include "android-base/mapped_file.h"
+#include "android-base/unique_fd.h"
+
+namespace android {
+namespace base {
+
+// These ABI-compatibility shims are in a separate file for two reasons:
+//   1. If they were in the file with the actual functions, it prevents calls to
+//      those functions by other functions in the file, due to ambiguity.
+//   2. We will hopefully be able to delete these quickly.
+
+#if !defined(_WIN32)
+ssize_t SendFileDescriptorVector(int sockfd, const void* data, size_t len,
+                                 const std::vector<int>& fds) {
+  return SendFileDescriptorVector(borrowed_fd(sockfd), data, len, fds);
+}
+
+ssize_t ReceiveFileDescriptorVector(int sockfd, void* data, size_t len, size_t max_fds,
+                                    std::vector<unique_fd>* fds) {
+  return ReceiveFileDescriptorVector(borrowed_fd(sockfd), data, len, max_fds, fds);
+}
+#endif
+
+bool ReadFdToString(int fd, std::string* content) {
+  return ReadFdToString(borrowed_fd(fd), content);
+}
+
+bool WriteStringToFd(const std::string& content, int fd) {
+  return WriteStringToFd(content, borrowed_fd(fd));
+}
+
+bool ReadFully(int fd, void* data, size_t byte_count) {
+  return ReadFully(borrowed_fd(fd), data, byte_count);
+}
+
+bool ReadFullyAtOffset(int fd, void* data, size_t byte_count, off64_t offset) {
+  return ReadFullyAtOffset(borrowed_fd(fd), data, byte_count, offset);
+}
+
+bool WriteFully(int fd, const void* data, size_t byte_count) {
+  return WriteFully(borrowed_fd(fd), data, byte_count);
+}
+
+#if defined(__LP64__)
+#define MAPPEDFILE_FROMFD _ZN10MappedFile6FromFdEilmi
+#else
+#define MAPPEDFILE_FROMFD _ZN10MappedFile6FromFdEixmi
+#endif
+
+#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
+extern "C" std::unique_ptr<MappedFile> MAPPEDFILE_FROMFD(int fd, off64_t offset, size_t length,
+                                                         int prot) {
+  return MappedFile::FromFd(fd, offset, length, prot);
+}
+
+}  // namespace base
+}  // namespace android
diff --git a/base/cmsg.cpp b/base/cmsg.cpp
index 42866f8..1fa873c 100644
--- a/base/cmsg.cpp
+++ b/base/cmsg.cpp
@@ -29,7 +29,7 @@
 namespace android {
 namespace base {
 
-ssize_t SendFileDescriptorVector(int sockfd, const void* data, size_t len,
+ssize_t SendFileDescriptorVector(borrowed_fd sockfd, const void* data, size_t len,
                                  const std::vector<int>& fds) {
   size_t cmsg_space = CMSG_SPACE(sizeof(int) * fds.size());
   size_t cmsg_len = CMSG_LEN(sizeof(int) * fds.size());
@@ -67,10 +67,10 @@
   int flags = 0;
 #endif
 
-  return TEMP_FAILURE_RETRY(sendmsg(sockfd, &msg, flags));
+  return TEMP_FAILURE_RETRY(sendmsg(sockfd.get(), &msg, flags));
 }
 
-ssize_t ReceiveFileDescriptorVector(int sockfd, void* data, size_t len, size_t max_fds,
+ssize_t ReceiveFileDescriptorVector(borrowed_fd sockfd, void* data, size_t len, size_t max_fds,
                                     std::vector<unique_fd>* fds) {
   fds->clear();
 
@@ -98,7 +98,7 @@
   flags |= MSG_CMSG_CLOEXEC | MSG_NOSIGNAL;
 #endif
 
-  ssize_t rc = TEMP_FAILURE_RETRY(recvmsg(sockfd, &msg, flags));
+  ssize_t rc = TEMP_FAILURE_RETRY(recvmsg(sockfd.get(), &msg, flags));
 
   if (rc == -1) {
     return -1;
diff --git a/base/file.cpp b/base/file.cpp
index adc8984..3dfcfbb 100644
--- a/base/file.cpp
+++ b/base/file.cpp
@@ -176,20 +176,20 @@
 // Versions of standard library APIs that support UTF-8 strings.
 using namespace android::base::utf8;
 
-bool ReadFdToString(int fd, std::string* content) {
+bool ReadFdToString(borrowed_fd fd, std::string* content) {
   content->clear();
 
   // Although original we had small files in mind, this code gets used for
   // very large files too, where the std::string growth heuristics might not
   // be suitable. https://code.google.com/p/android/issues/detail?id=258500.
   struct stat sb;
-  if (fstat(fd, &sb) != -1 && sb.st_size > 0) {
+  if (fstat(fd.get(), &sb) != -1 && sb.st_size > 0) {
     content->reserve(sb.st_size);
   }
 
   char buf[BUFSIZ];
   ssize_t n;
-  while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) {
+  while ((n = TEMP_FAILURE_RETRY(read(fd.get(), &buf[0], sizeof(buf)))) > 0) {
     content->append(buf, n);
   }
   return (n == 0) ? true : false;
@@ -206,11 +206,11 @@
   return ReadFdToString(fd, content);
 }
 
-bool WriteStringToFd(const std::string& content, int fd) {
+bool WriteStringToFd(const std::string& content, borrowed_fd fd) {
   const char* p = content.data();
   size_t left = content.size();
   while (left > 0) {
-    ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left));
+    ssize_t n = TEMP_FAILURE_RETRY(write(fd.get(), p, left));
     if (n == -1) {
       return false;
     }
@@ -269,11 +269,11 @@
   return WriteStringToFd(content, fd) || CleanUpAfterFailedWrite(path);
 }
 
-bool ReadFully(int fd, void* data, size_t byte_count) {
+bool ReadFully(borrowed_fd fd, void* data, size_t byte_count) {
   uint8_t* p = reinterpret_cast<uint8_t*>(data);
   size_t remaining = byte_count;
   while (remaining > 0) {
-    ssize_t n = TEMP_FAILURE_RETRY(read(fd, p, remaining));
+    ssize_t n = TEMP_FAILURE_RETRY(read(fd.get(), p, remaining));
     if (n <= 0) return false;
     p += n;
     remaining -= n;
@@ -284,14 +284,14 @@
 #if defined(_WIN32)
 // Windows implementation of pread. Note that this DOES move the file descriptors read position,
 // but it does so atomically.
-static ssize_t pread(int fd, void* data, size_t byte_count, off64_t offset) {
+static ssize_t pread(borrowed_fd fd, void* data, size_t byte_count, off64_t offset) {
   DWORD bytes_read;
   OVERLAPPED overlapped;
   memset(&overlapped, 0, sizeof(OVERLAPPED));
   overlapped.Offset = static_cast<DWORD>(offset);
   overlapped.OffsetHigh = static_cast<DWORD>(offset >> 32);
-  if (!ReadFile(reinterpret_cast<HANDLE>(_get_osfhandle(fd)), data, static_cast<DWORD>(byte_count),
-                &bytes_read, &overlapped)) {
+  if (!ReadFile(reinterpret_cast<HANDLE>(_get_osfhandle(fd.get())), data,
+                static_cast<DWORD>(byte_count), &bytes_read, &overlapped)) {
     // In case someone tries to read errno (since this is masquerading as a POSIX call)
     errno = EIO;
     return -1;
@@ -300,10 +300,10 @@
 }
 #endif
 
-bool ReadFullyAtOffset(int fd, void* data, size_t byte_count, off64_t offset) {
+bool ReadFullyAtOffset(borrowed_fd fd, void* data, size_t byte_count, off64_t offset) {
   uint8_t* p = reinterpret_cast<uint8_t*>(data);
   while (byte_count > 0) {
-    ssize_t n = TEMP_FAILURE_RETRY(pread(fd, p, byte_count, offset));
+    ssize_t n = TEMP_FAILURE_RETRY(pread(fd.get(), p, byte_count, offset));
     if (n <= 0) return false;
     p += n;
     byte_count -= n;
@@ -312,11 +312,11 @@
   return true;
 }
 
-bool WriteFully(int fd, const void* data, size_t byte_count) {
+bool WriteFully(borrowed_fd fd, const void* data, size_t byte_count) {
   const uint8_t* p = reinterpret_cast<const uint8_t*>(data);
   size_t remaining = byte_count;
   while (remaining > 0) {
-    ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, remaining));
+    ssize_t n = TEMP_FAILURE_RETRY(write(fd.get(), p, remaining));
     if (n == -1) return false;
     p += n;
     remaining -= n;
diff --git a/base/include/android-base/cmsg.h b/base/include/android-base/cmsg.h
index 7f93ddc..e4197b1 100644
--- a/base/include/android-base/cmsg.h
+++ b/base/include/android-base/cmsg.h
@@ -51,20 +51,20 @@
 // Note that the write can return short if the socket type is SOCK_STREAM. When
 // this happens, file descriptors are still sent to the other end, but with
 // truncated data. For this reason, using SOCK_SEQPACKET or SOCK_DGRAM is recommended.
-ssize_t SendFileDescriptorVector(int sock, const void* data, size_t len,
+ssize_t SendFileDescriptorVector(borrowed_fd sock, const void* data, size_t len,
                                  const std::vector<int>& fds);
 
 // Receive file descriptors from a Unix domain socket.
 //
 // If more FDs (or bytes, for datagram sockets) are received than expected,
 // -1 is returned with errno set to EMSGSIZE, and all received FDs are thrown away.
-ssize_t ReceiveFileDescriptorVector(int sock, void* data, size_t len, size_t max_fds,
+ssize_t ReceiveFileDescriptorVector(borrowed_fd sock, void* data, size_t len, size_t max_fds,
                                     std::vector<android::base::unique_fd>* fds);
 
 // Helper for SendFileDescriptorVector that constructs a std::vector for you, e.g.:
 //   SendFileDescriptors(sock, "foo", 3, std::move(fd1), std::move(fd2))
 template <typename... Args>
-ssize_t SendFileDescriptors(int sock, const void* data, size_t len, Args&&... sent_fds) {
+ssize_t SendFileDescriptors(borrowed_fd sock, const void* data, size_t len, Args&&... sent_fds) {
   // Do not allow implicit conversion to int: people might try to do something along the lines of:
   //   SendFileDescriptors(..., std::move(a_unique_fd))
   // and be surprised when the unique_fd isn't closed afterwards.
@@ -79,7 +79,7 @@
 // If fewer file descriptors are received than requested, -1 is returned with errno set to ENOMSG.
 // In both cases, all arguments are cleared and any received FDs are thrown away.
 template <typename... Args>
-ssize_t ReceiveFileDescriptors(int sock, void* data, size_t len, Args&&... received_fds) {
+ssize_t ReceiveFileDescriptors(borrowed_fd sock, void* data, size_t len, Args&&... received_fds) {
   std::vector<unique_fd*> fds;
   Append(fds, std::forward<Args>(received_fds)...);
 
diff --git a/base/include/android-base/file.h b/base/include/android-base/file.h
index f8748b5..c622562 100644
--- a/base/include/android-base/file.h
+++ b/base/include/android-base/file.h
@@ -21,8 +21,9 @@
 
 #include <string>
 
-#include <android-base/macros.h>
+#include "android-base/macros.h"
 #include "android-base/off64_t.h"
+#include "android-base/unique_fd.h"
 
 #if !defined(_WIN32) && !defined(O_BINARY)
 /** Windows needs O_BINARY, but Unix never mangles line endings. */
@@ -77,13 +78,13 @@
 namespace android {
 namespace base {
 
-bool ReadFdToString(int fd, std::string* content);
+bool ReadFdToString(borrowed_fd fd, std::string* content);
 bool ReadFileToString(const std::string& path, std::string* content,
                       bool follow_symlinks = false);
 
 bool WriteStringToFile(const std::string& content, const std::string& path,
                        bool follow_symlinks = false);
-bool WriteStringToFd(const std::string& content, int fd);
+bool WriteStringToFd(const std::string& content, borrowed_fd fd);
 
 #if !defined(_WIN32)
 bool WriteStringToFile(const std::string& content, const std::string& path,
@@ -91,7 +92,7 @@
                        bool follow_symlinks = false);
 #endif
 
-bool ReadFully(int fd, void* data, size_t byte_count);
+bool ReadFully(borrowed_fd fd, void* data, size_t byte_count);
 
 // Reads `byte_count` bytes from the file descriptor at the specified offset.
 // Returns false if there was an IO error or EOF was reached before reading `byte_count` bytes.
@@ -101,9 +102,9 @@
 // get modified. This means that ReadFullyAtOffset can be used concurrently with other calls to the
 // same function, but concurrently seeking or reading incrementally can lead to unexpected
 // behavior.
-bool ReadFullyAtOffset(int fd, void* data, size_t byte_count, off64_t offset);
+bool ReadFullyAtOffset(borrowed_fd fd, void* data, size_t byte_count, off64_t offset);
 
-bool WriteFully(int fd, const void* data, size_t byte_count);
+bool WriteFully(borrowed_fd fd, const void* data, size_t byte_count);
 
 bool RemoveFileIfExists(const std::string& path, std::string* err = nullptr);
 
diff --git a/base/include/android-base/mapped_file.h b/base/include/android-base/mapped_file.h
index 80513b1..b719646 100644
--- a/base/include/android-base/mapped_file.h
+++ b/base/include/android-base/mapped_file.h
@@ -16,13 +16,14 @@
 
 #pragma once
 
-#include "android-base/macros.h"
-#include "android-base/off64_t.h"
-
 #include <sys/types.h>
 
 #include <memory>
 
+#include "android-base/macros.h"
+#include "android-base/off64_t.h"
+#include "android-base/unique_fd.h"
+
 #if defined(_WIN32)
 #include <windows.h>
 #define PROT_READ 1
@@ -44,7 +45,8 @@
    * `offset` does not need to be page-aligned. If `PROT_WRITE` is set in `prot`, the mapping
    * will be writable, otherwise it will be read-only. Mappings are always `MAP_SHARED`.
    */
-  static std::unique_ptr<MappedFile> FromFd(int fd, off64_t offset, size_t length, int prot);
+  static std::unique_ptr<MappedFile> FromFd(borrowed_fd fd, off64_t offset, size_t length,
+                                            int prot);
 
   /**
    * Removes the mapping.
diff --git a/base/include/android-base/unique_fd.h b/base/include/android-base/unique_fd.h
index 3fa3bea..3a02cff 100644
--- a/base/include/android-base/unique_fd.h
+++ b/base/include/android-base/unique_fd.h
@@ -103,7 +103,17 @@
   void reset(int new_value = -1) { reset(new_value, nullptr); }
 
   int get() const { return fd_; }
+
+#if !defined(ANDROID_BASE_UNIQUE_FD_DISABLE_IMPLICIT_CONVERSION)
+  // unique_fd's operator int is dangerous, but we have way too much code that
+  // depends on it, so make this opt-in at first.
   operator int() const { return get(); }  // NOLINT
+#endif
+
+  bool operator>=(int rhs) const { return get() >= rhs; }
+  bool operator<(int rhs) const { return get() < rhs; }
+  bool operator==(int rhs) const { return get() == rhs; }
+  bool operator!=(int rhs) const { return get() != rhs; }
 
   // Catch bogus error checks (i.e.: "!fd" instead of "fd != -1").
   bool operator!() const = delete;
@@ -246,6 +256,22 @@
 
 #endif  // !defined(_WIN32)
 
+// A wrapper type that can be implicitly constructed from either int or unique_fd.
+struct borrowed_fd {
+  /* implicit */ borrowed_fd(int fd) : fd_(fd) {}
+  template <typename T>
+  /* implicit */ borrowed_fd(const unique_fd_impl<T>& ufd) : fd_(ufd.get()) {}
+
+  int get() const { return fd_; }
+
+  bool operator>=(int rhs) const { return get() >= rhs; }
+  bool operator<(int rhs) const { return get() < rhs; }
+  bool operator==(int rhs) const { return get() == rhs; }
+  bool operator!=(int rhs) const { return get() != rhs; }
+
+ private:
+  int fd_ = -1;
+};
 }  // namespace base
 }  // namespace android
 
diff --git a/base/mapped_file.cpp b/base/mapped_file.cpp
index 7c65dc3..f689bfa 100644
--- a/base/mapped_file.cpp
+++ b/base/mapped_file.cpp
@@ -18,6 +18,8 @@
 
 #include <errno.h>
 
+#include "android-base/unique_fd.h"
+
 namespace android {
 namespace base {
 
@@ -31,7 +33,8 @@
 #endif
 }
 
-std::unique_ptr<MappedFile> MappedFile::FromFd(int fd, off64_t offset, size_t length, int prot) {
+std::unique_ptr<MappedFile> MappedFile::FromFd(borrowed_fd fd, off64_t offset, size_t length,
+                                               int prot) {
   static off64_t page_size = InitPageSize();
   size_t slop = offset % page_size;
   off64_t file_offset = offset - slop;
@@ -39,7 +42,7 @@
 
 #if defined(_WIN32)
   HANDLE handle =
-      CreateFileMapping(reinterpret_cast<HANDLE>(_get_osfhandle(fd)), nullptr,
+      CreateFileMapping(reinterpret_cast<HANDLE>(_get_osfhandle(fd.get())), nullptr,
                         (prot & PROT_WRITE) ? PAGE_READWRITE : PAGE_READONLY, 0, 0, nullptr);
   if (handle == nullptr) {
     // http://b/119818070 "app crashes when reading asset of zero length".
@@ -58,7 +61,7 @@
   return std::unique_ptr<MappedFile>(
       new MappedFile{static_cast<char*>(base), length, slop, handle});
 #else
-  void* base = mmap(nullptr, file_length, prot, MAP_SHARED, fd, file_offset);
+  void* base = mmap(nullptr, file_length, prot, MAP_SHARED, fd.get(), file_offset);
   if (base == MAP_FAILED) {
     // http://b/119818070 "app crashes when reading asset of zero length".
     // mmap fails with EINVAL for a zero length region.
diff --git a/debuggerd/crash_dump.cpp b/debuggerd/crash_dump.cpp
index c608a8c..cb55745 100644
--- a/debuggerd/crash_dump.cpp
+++ b/debuggerd/crash_dump.cpp
@@ -463,6 +463,7 @@
       ThreadInfo info;
       info.pid = target_process;
       info.tid = thread;
+      info.uid = getuid();
       info.process_name = process_name;
       info.thread_name = get_thread_name(thread);
 
diff --git a/fastboot/fuzzy_fastboot/main.cpp b/fastboot/fuzzy_fastboot/main.cpp
index ff918a7..a1d69d2 100644
--- a/fastboot/fuzzy_fastboot/main.cpp
+++ b/fastboot/fuzzy_fastboot/main.cpp
@@ -244,16 +244,29 @@
 // Testing creation/resize/delete of logical partitions
 TEST_F(LogicalPartitionCompliance, CreateResizeDeleteLP) {
     ASSERT_TRUE(UserSpaceFastboot());
+    std::string test_partition_name = "test_partition";
+    std::string slot_count;
+    // Add suffix to test_partition_name if device is slotted.
+    EXPECT_EQ(fb->GetVar("slot-count", &slot_count), SUCCESS) << "getvar slot-count failed";
+    int32_t num_slots = strtol(slot_count.c_str(), nullptr, 10);
+    if (num_slots > 0) {
+        std::string current_slot;
+        EXPECT_EQ(fb->GetVar("current-slot", &current_slot), SUCCESS)
+                << "getvar current-slot failed";
+        std::string slot_suffix = "_" + current_slot;
+        test_partition_name += slot_suffix;
+    }
+
     GTEST_LOG_(INFO) << "Testing 'fastboot create-logical-partition' command";
-    EXPECT_EQ(fb->CreatePartition("test_partition_a", "0"), SUCCESS)
+    EXPECT_EQ(fb->CreatePartition(test_partition_name, "0"), SUCCESS)
             << "create-logical-partition failed";
     GTEST_LOG_(INFO) << "Testing 'fastboot resize-logical-partition' command";
-    EXPECT_EQ(fb->ResizePartition("test_partition_a", "4096"), SUCCESS)
+    EXPECT_EQ(fb->ResizePartition(test_partition_name, "4096"), SUCCESS)
             << "resize-logical-partition failed";
     std::vector<char> buf(4096);
 
     GTEST_LOG_(INFO) << "Flashing a logical partition..";
-    EXPECT_EQ(fb->FlashPartition("test_partition_a", buf), SUCCESS)
+    EXPECT_EQ(fb->FlashPartition(test_partition_name, buf), SUCCESS)
             << "flash logical -partition failed";
     GTEST_LOG_(INFO) << "Rebooting to bootloader mode";
     // Reboot to bootloader mode and attempt to flash the logical partitions
@@ -262,7 +275,7 @@
     ReconnectFastbootDevice();
     ASSERT_FALSE(UserSpaceFastboot());
     GTEST_LOG_(INFO) << "Attempt to flash a logical partition..";
-    EXPECT_EQ(fb->FlashPartition("test_partition", buf), DEVICE_FAIL)
+    EXPECT_EQ(fb->FlashPartition(test_partition_name, buf), DEVICE_FAIL)
             << "flash logical partition must fail in bootloader";
     GTEST_LOG_(INFO) << "Rebooting back to fastbootd mode";
     fb->RebootTo("fastboot");
@@ -270,7 +283,7 @@
     ReconnectFastbootDevice();
     ASSERT_TRUE(UserSpaceFastboot());
     GTEST_LOG_(INFO) << "Testing 'fastboot delete-logical-partition' command";
-    EXPECT_EQ(fb->DeletePartition("test_partition_a"), SUCCESS)
+    EXPECT_EQ(fb->DeletePartition(test_partition_name), SUCCESS)
             << "delete logical-partition failed";
 }
 
diff --git a/fastboot/usb_osx.cpp b/fastboot/usb_osx.cpp
index f597f50..8a3c213 100644
--- a/fastboot/usb_osx.cpp
+++ b/fastboot/usb_osx.cpp
@@ -106,7 +106,7 @@
     kr = (*dev)->CreateInterfaceIterator(dev, &request, &iterator);
 
     if (kr != 0) {
-        ERR("Couldn't create a device interface iterator: (%08x)\n", kr);
+        WARN("Couldn't create a device interface iterator: (%08x)\n", kr);
         return -1;
     }
 
diff --git a/fs_mgr/README.overlayfs.md b/fs_mgr/README.overlayfs.md
index f89e598..d204bfd 100644
--- a/fs_mgr/README.overlayfs.md
+++ b/fs_mgr/README.overlayfs.md
@@ -117,3 +117,25 @@
   be used to clear scratch storage to permit the flash.
   Then reinstate the overrides and continue.
 - File bugs or submit fixes for review.
+- There are other subtle caveats requiring complex logic to solve.
+  Have evaluated them as too complex or not worth the trouble, please
+  File a bug if a use case needs to be covered.
+  - The backing storage is treated fragile, if anything else has
+    issue with the space taken, the backing storage will be cleared
+    out and we reserve the right to not inform, if the layering
+    does not prevent any messaging.
+  - Space remaining threshold is hard coded.  If 1% or more space
+    still remains, overlayfs will not be used, yet that amount of
+    space remaining is problematic.
+  - Flashing a partition via bootloader fastboot, as opposed to user
+    space fastbootd, is not detected, thus a partition may have
+    override content remaining.  adb enable-verity to wipe.
+  - Space is limited, there is near unlimited space on userdata,
+    we have made an architectural decision to not utilize
+    /data/overlay/ at this time.  Acquiring space to use for
+    backing remains an ongoing battle.
+  - First stage init, or ramdisk, can not be overriden.
+  - Backing storage will be discarded or ignored on errors, leading
+    to confusion.  When debugging using **adb remount** it is
+    currently advised to confirm update is present after a reboot
+    to develop confidence.
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 6f24fe1..56ea92c 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -390,7 +390,7 @@
 // Set the number of reserved filesystem blocks if needed.
 static void tune_reserved_size(const std::string& blk_device, const FstabEntry& entry,
                                const struct ext4_super_block* sb, int* fs_stat) {
-    if (entry.reserved_size != 0) {
+    if (entry.reserved_size == 0) {
         return;
     }
 
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 78455d4..0cbdcce 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -700,7 +700,9 @@
     constexpr const char kSkipMountConfig[] = "/system/etc/init/config/skip_mount.cfg";
 
     std::string skip_config;
+    auto save_errno = errno;
     if (!ReadFileToString(kSkipMountConfig, &skip_config)) {
+        errno = save_errno;  // missing file is expected
         return true;
     }
 
@@ -801,8 +803,11 @@
 std::string GetVerityDeviceName(const FstabEntry& entry) {
     std::string base_device;
     if (entry.mount_point == "/") {
-        // In AVB, the dm device name is vroot instead of system.
-        base_device = entry.fs_mgr_flags.avb ? "vroot" : "system";
+        // When using system-as-root, the device name is fixed as "vroot".
+        if (entry.fs_mgr_flags.avb) {
+            return "vroot";
+        }
+        base_device = "system";
     } else {
         base_device = android::base::Basename(entry.mount_point);
     }
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index 71c4072..a649975 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -139,7 +139,11 @@
     // If we have access issues to find out space remaining, return true
     // to prevent us trying to override with overlayfs.
     struct statvfs vst;
-    if (statvfs(mount_point.c_str(), &vst)) return true;
+    auto save_errno = errno;
+    if (statvfs(mount_point.c_str(), &vst)) {
+        errno = save_errno;
+        return true;
+    }
 
     static constexpr int kPercentThreshold = 1;  // 1%
 
@@ -265,9 +269,11 @@
 
 bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true) {
     Fstab fstab;
+    auto save_errno = errno;
     if (!ReadFstabFromFile("/proc/mounts", &fstab)) {
         return false;
     }
+    errno = save_errno;
     const auto lowerdir = kLowerdirOption + mount_point;
     for (const auto& entry : fstab) {
         if (overlay_only && "overlay" != entry.fs_type && "overlayfs" != entry.fs_type) continue;
diff --git a/fs_mgr/fs_mgr_remount.cpp b/fs_mgr/fs_mgr_remount.cpp
index 00334bc..6482ed3 100644
--- a/fs_mgr/fs_mgr_remount.cpp
+++ b/fs_mgr/fs_mgr_remount.cpp
@@ -256,7 +256,7 @@
         auto& mount_point = entry.mount_point;
         if (fs_mgr_is_verity_enabled(entry)) {
             retval = VERITY_PARTITION;
-            if (android::base::GetProperty("ro.boot.vbmeta.devices_state", "") != "locked") {
+            if (android::base::GetProperty("ro.boot.vbmeta.device_state", "") != "locked") {
                 if (AvbOps* ops = avb_ops_user_new()) {
                     auto ret = avb_user_verity_set(
                             ops, android::base::GetProperty("ro.boot.slot_suffix", "").c_str(),
diff --git a/fs_mgr/fs_mgr_roots.cpp b/fs_mgr/fs_mgr_roots.cpp
index 58ef9b6..1e65587 100644
--- a/fs_mgr/fs_mgr_roots.cpp
+++ b/fs_mgr/fs_mgr_roots.cpp
@@ -101,7 +101,9 @@
         }
     }
 
-    auto mounted = GetMountState(rec->mount_point);
+    const std::string mount_point = mount_pt.empty() ? rec->mount_point : mount_pt;
+
+    auto mounted = GetMountState(mount_point);
     if (mounted == MountState::ERROR) {
         return false;
     }
@@ -109,8 +111,6 @@
         return true;
     }
 
-    const std::string mount_point = mount_pt.empty() ? rec->mount_point : mount_pt;
-
     static const std::vector<std::string> supported_fs{"ext4", "squashfs", "vfat", "f2fs", "none"};
     if (std::find(supported_fs.begin(), supported_fs.end(), rec->fs_type) == supported_fs.end()) {
         LERROR << "unknown fs_type \"" << rec->fs_type << "\" for " << mount_point;
diff --git a/fs_mgr/libdm/dm_target.cpp b/fs_mgr/libdm/dm_target.cpp
index f440e6d..da1013e 100644
--- a/fs_mgr/libdm/dm_target.cpp
+++ b/fs_mgr/libdm/dm_target.cpp
@@ -16,6 +16,9 @@
 
 #include "libdm/dm_target.h"
 
+#include <stdio.h>
+#include <sys/types.h>
+
 #include <android-base/logging.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
@@ -193,5 +196,30 @@
     return true;
 }
 
+std::string DmTargetCrypt::GetParameterString() const {
+    std::vector<std::string> argv = {
+            cipher_,
+            key_,
+            std::to_string(iv_sector_offset_),
+            device_,
+            std::to_string(device_sector_),
+    };
+
+    std::vector<std::string> extra_argv;
+    if (allow_discards_) extra_argv.emplace_back("allow_discards");
+    if (allow_encrypt_override_) extra_argv.emplace_back("allow_encrypt_override");
+    if (iv_large_sectors_) extra_argv.emplace_back("iv_large_sectors");
+    if (sector_size_) extra_argv.emplace_back("sector_size:" + std::to_string(sector_size_));
+
+    if (!extra_argv.empty()) argv.emplace_back(std::to_string(extra_argv.size()));
+
+    argv.insert(argv.end(), extra_argv.begin(), extra_argv.end());
+    return android::base::Join(argv, " ");
+}
+
+std::string DmTargetDefaultKey::GetParameterString() const {
+    return cipher_ + " " + key_ + " " + blockdev_ + " " + std::to_string(start_sector_);
+}
+
 }  // namespace dm
 }  // namespace android
diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index 72a0e11..dc47c33 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -438,3 +438,26 @@
         ASSERT_EQ(status.error, "Invalid");
     }
 }
+
+TEST(libdm, CryptArgs) {
+    DmTargetCrypt target1(0, 512, "sha1", "abcdefgh", 50, "/dev/loop0", 100);
+    ASSERT_EQ(target1.name(), "crypt");
+    ASSERT_TRUE(target1.Valid());
+    ASSERT_EQ(target1.GetParameterString(), "sha1 abcdefgh 50 /dev/loop0 100");
+
+    DmTargetCrypt target2(0, 512, "sha1", "abcdefgh", 50, "/dev/loop0", 100);
+    target2.SetSectorSize(64);
+    target2.AllowDiscards();
+    target2.SetIvLargeSectors();
+    target2.AllowEncryptOverride();
+    ASSERT_EQ(target2.GetParameterString(),
+              "sha1 abcdefgh 50 /dev/loop0 100 4 allow_discards allow_encrypt_override "
+              "iv_large_sectors sector_size:64");
+}
+
+TEST(libdm, DefaultKeyArgs) {
+    DmTargetDefaultKey target(0, 4096, "AES-256-XTS", "abcdef0123456789", "/dev/loop0", 0);
+    ASSERT_EQ(target.name(), "default-key");
+    ASSERT_TRUE(target.Valid());
+    ASSERT_EQ(target.GetParameterString(), "AES-256-XTS abcdef0123456789 /dev/loop0 0");
+}
diff --git a/fs_mgr/libdm/include/libdm/dm_table.h b/fs_mgr/libdm/include/libdm/dm_table.h
index 5c639be..ee66653 100644
--- a/fs_mgr/libdm/include/libdm/dm_table.h
+++ b/fs_mgr/libdm/include/libdm/dm_table.h
@@ -43,12 +43,20 @@
     // successfully removed.
     bool RemoveTarget(std::unique_ptr<DmTarget>&& target);
 
+    // Adds a target, constructing it in-place for convenience. For example,
+    //
+    //   table.Emplace<DmTargetZero>(0, num_sectors);
+    template <typename T, typename... Args>
+    bool Emplace(Args&&... args) {
+        return AddTarget(std::make_unique<T>(std::forward<Args>(args)...));
+    }
+
     // Checks the table to make sure it is valid. i.e. Checks for range overlaps, range gaps
     // and returns 'true' if the table is ready to be loaded into kernel. Returns 'false' if the
     // table is malformed.
     bool valid() const;
 
-    // Returns the toatl number of targets.
+    // Returns the total number of targets.
     size_t num_targets() const { return targets_.size(); }
 
     // Returns the total size represented by the table in terms of number of 512-byte sectors.
diff --git a/fs_mgr/libdm/include/libdm/dm_target.h b/fs_mgr/libdm/include/libdm/dm_target.h
index fce1175..722922d 100644
--- a/fs_mgr/libdm/include/libdm/dm_target.h
+++ b/fs_mgr/libdm/include/libdm/dm_target.h
@@ -241,6 +241,60 @@
     std::string device_;
 };
 
+class DmTargetCrypt final : public DmTarget {
+  public:
+    DmTargetCrypt(uint64_t start, uint64_t length, const std::string& cipher,
+                  const std::string& key, uint64_t iv_sector_offset, const std::string& device,
+                  uint64_t device_sector)
+        : DmTarget(start, length),
+          cipher_(cipher),
+          key_(key),
+          iv_sector_offset_(iv_sector_offset),
+          device_(device),
+          device_sector_(device_sector) {}
+
+    void AllowDiscards() { allow_discards_ = true; }
+    void AllowEncryptOverride() { allow_encrypt_override_ = true; }
+    void SetIvLargeSectors() { iv_large_sectors_ = true; }
+    void SetSectorSize(uint32_t sector_size) { sector_size_ = sector_size; }
+
+    std::string name() const override { return "crypt"; }
+    bool Valid() const override { return true; }
+    std::string GetParameterString() const override;
+
+  private:
+    std::string cipher_;
+    std::string key_;
+    uint64_t iv_sector_offset_;
+    std::string device_;
+    uint64_t device_sector_;
+    bool allow_discards_ = false;
+    bool allow_encrypt_override_ = false;
+    bool iv_large_sectors_ = false;
+    uint32_t sector_size_ = 0;
+};
+
+class DmTargetDefaultKey final : public DmTarget {
+  public:
+    DmTargetDefaultKey(uint64_t start, uint64_t length, const std::string& cipher,
+                       const std::string& key, const std::string& blockdev, uint64_t start_sector)
+        : DmTarget(start, length),
+          cipher_(cipher),
+          key_(key),
+          blockdev_(blockdev),
+          start_sector_(start_sector) {}
+
+    std::string name() const override { return "default-key"; }
+    bool Valid() const override { return true; }
+    std::string GetParameterString() const override;
+
+  private:
+    std::string cipher_;
+    std::string key_;
+    std::string blockdev_;
+    uint64_t start_sector_;
+};
+
 }  // namespace dm
 }  // namespace android
 
diff --git a/init/README.md b/init/README.md
index c4505fe..806bfa7 100644
--- a/init/README.md
+++ b/init/README.md
@@ -414,7 +414,8 @@
 
 `class_start_post_data <serviceclass>`
 > Like `class_start`, but only considers services that were started
-  after /data was mounted. Only used for FDE devices.
+  after /data was mounted, and that were running at the time
+ `class_reset_post_data` was called. Only used for FDE devices.
 
 `class_stop <serviceclass>`
 > Stop and disable all services of the specified class if they are
diff --git a/init/builtins.cpp b/init/builtins.cpp
index ba1c94d..6ce7736 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -104,35 +104,36 @@
     }
 }
 
-static Result<Success> class_start(const std::string& class_name, bool post_data_only) {
+static Result<Success> do_class_start(const BuiltinArguments& args) {
     // Do not start a class if it has a property persist.dont_start_class.CLASS set to 1.
-    if (android::base::GetBoolProperty("persist.init.dont_start_class." + class_name, false))
+    if (android::base::GetBoolProperty("persist.init.dont_start_class." + args[1], false))
         return Success();
     // Starting a class does not start services which are explicitly disabled.
     // They must  be started individually.
     for (const auto& service : ServiceList::GetInstance()) {
-        if (service->classnames().count(class_name)) {
-            if (post_data_only && !service->is_post_data()) {
-                continue;
-            }
+        if (service->classnames().count(args[1])) {
             if (auto result = service->StartIfNotDisabled(); !result) {
                 LOG(ERROR) << "Could not start service '" << service->name()
-                           << "' as part of class '" << class_name << "': " << result.error();
+                           << "' as part of class '" << args[1] << "': " << result.error();
             }
         }
     }
     return Success();
 }
 
-static Result<Success> do_class_start(const BuiltinArguments& args) {
-    return class_start(args[1], false /* post_data_only */);
-}
-
 static Result<Success> do_class_start_post_data(const BuiltinArguments& args) {
     if (args.context != kInitContext) {
         return Error() << "command 'class_start_post_data' only available in init context";
     }
-    return class_start(args[1], true /* post_data_only */);
+    for (const auto& service : ServiceList::GetInstance()) {
+        if (service->classnames().count(args[1])) {
+            if (auto result = service->StartIfPostData(); !result) {
+                LOG(ERROR) << "Could not start service '" << service->name()
+                           << "' as part of class '" << args[1] << "': " << result.error();
+            }
+        }
+    }
+    return Success();
 }
 
 static Result<Success> do_class_stop(const BuiltinArguments& args) {
diff --git a/init/first_stage_init.cpp b/init/first_stage_init.cpp
index f069c58..7dd3ad4 100644
--- a/init/first_stage_init.cpp
+++ b/init/first_stage_init.cpp
@@ -235,7 +235,7 @@
 
     SetInitAvbVersionInRecovery();
 
-    setenv("FIRST_STAGE_STARTED_AT", std::to_string(start_time.time_since_epoch().count()).c_str(),
+    setenv(kEnvFirstStageStartedAt, std::to_string(start_time.time_since_epoch().count()).c_str(),
            1);
 
     const char* path = "/system/bin/init";
diff --git a/init/first_stage_init.h b/init/first_stage_init.h
index 0476e44..7de816f 100644
--- a/init/first_stage_init.h
+++ b/init/first_stage_init.h
@@ -21,5 +21,7 @@
 
 int FirstStageMain(int argc, char** argv);
 
+static constexpr char kEnvFirstStageStartedAt[] = "FIRST_STAGE_STARTED_AT";
+
 }  // namespace init
 }  // namespace android
diff --git a/init/init.cpp b/init/init.cpp
index a18c2c8..1f3c2fc 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -56,6 +56,7 @@
 #include "action_parser.h"
 #include "boringssl_self_test.h"
 #include "epoll.h"
+#include "first_stage_init.h"
 #include "first_stage_mount.h"
 #include "import_parser.h"
 #include "keychords.h"
@@ -630,20 +631,18 @@
 
 static void RecordStageBoottimes(const boot_clock::time_point& second_stage_start_time) {
     int64_t first_stage_start_time_ns = -1;
-    static constexpr char first_stage_started_at[] = "FIRST_STAGE_STARTED_AT";
-    if (auto first_stage_start_time_str = getenv(first_stage_started_at);
+    if (auto first_stage_start_time_str = getenv(kEnvFirstStageStartedAt);
         first_stage_start_time_str) {
         property_set("ro.boottime.init", first_stage_start_time_str);
         android::base::ParseInt(first_stage_start_time_str, &first_stage_start_time_ns);
     }
-    unsetenv(first_stage_started_at);
+    unsetenv(kEnvFirstStageStartedAt);
 
     int64_t selinux_start_time_ns = -1;
-    static constexpr char selinux_started_at[] = "SELINUX_STARTED_AT";
-    if (auto selinux_start_time_str = getenv(selinux_started_at); selinux_start_time_str) {
+    if (auto selinux_start_time_str = getenv(kEnvSelinuxStartedAt); selinux_start_time_str) {
         android::base::ParseInt(selinux_start_time_str, &selinux_start_time_ns);
     }
-    unsetenv(selinux_started_at);
+    unsetenv(kEnvSelinuxStartedAt);
 
     if (selinux_start_time_ns == -1) return;
     if (first_stage_start_time_ns == -1) return;
diff --git a/init/selinux.cpp b/init/selinux.cpp
index f897170..8a63363 100644
--- a/init/selinux.cpp
+++ b/init/selinux.cpp
@@ -544,7 +544,7 @@
         PLOG(FATAL) << "restorecon failed of /system/bin/init failed";
     }
 
-    setenv("SELINUX_STARTED_AT", std::to_string(start_time.time_since_epoch().count()).c_str(), 1);
+    setenv(kEnvSelinuxStartedAt, std::to_string(start_time.time_since_epoch().count()).c_str(), 1);
 
     const char* path = "/system/bin/init";
     const char* args[] = {path, "second_stage", nullptr};
diff --git a/init/selinux.h b/init/selinux.h
index 3aa9406..c7d6647 100644
--- a/init/selinux.h
+++ b/init/selinux.h
@@ -35,6 +35,8 @@
                                        const std::vector<std::string>& aliases, int type,
                                        std::string* result);
 
+static constexpr char kEnvSelinuxStartedAt[] = "SELINUX_STARTED_AT";
+
 }  // namespace init
 }  // namespace android
 
diff --git a/init/service.cpp b/init/service.cpp
index 2f96681..ccc37b7 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -1154,10 +1154,23 @@
 
 void Service::ResetIfPostData() {
     if (post_data_) {
+        if (flags_ & SVC_RUNNING) {
+            running_at_post_data_reset_ = true;
+        }
         StopOrReset(SVC_RESET);
     }
 }
 
+Result<Success> Service::StartIfPostData() {
+    // Start the service, but only if it was started after /data was mounted,
+    // and it was still running when we reset the post-data services.
+    if (running_at_post_data_reset_) {
+        return Start();
+    }
+
+    return Success();
+}
+
 void Service::Stop() {
     StopOrReset(SVC_DISABLED);
 }
diff --git a/init/service.h b/init/service.h
index dc2b128..ae29f28 100644
--- a/init/service.h
+++ b/init/service.h
@@ -79,6 +79,7 @@
     Result<Success> ExecStart();
     Result<Success> Start();
     Result<Success> StartIfNotDisabled();
+    Result<Success> StartIfPostData();
     Result<Success> Enable();
     void Reset();
     void ResetIfPostData();
@@ -248,6 +249,8 @@
     bool pre_apexd_ = false;
 
     bool post_data_ = false;
+
+    bool running_at_post_data_reset_ = false;
 };
 
 class ServiceList {
diff --git a/libnativeloader/Android.bp b/libnativeloader/Android.bp
index 3b77a9e..debc43f 100644
--- a/libnativeloader/Android.bp
+++ b/libnativeloader/Android.bp
@@ -30,6 +30,7 @@
         android: {
             srcs: [
                 "library_namespaces.cpp",
+                "native_loader_namespace.cpp",
                 "public_libraries.cpp",
             ],
             shared_libs: [
diff --git a/libnativeloader/README.md b/libnativeloader/README.md
new file mode 100644
index 0000000..46f6fdd
--- /dev/null
+++ b/libnativeloader/README.md
@@ -0,0 +1,84 @@
+libnativeloader
+===============================================================================
+
+Overview
+-------------------------------------------------------------------------------
+libnativeloader is responsible for loading native shared libraries (`*.so`
+files) inside the Android Runtime (ART). The native shared libraries could be
+app-provided JNI libraries or public native libraries like `libc.so` provided
+by the platform.
+
+The most typical use case of this library is calling `System.loadLibrary(name)`.
+When the method is called, the ART runtime delegates the call to this library
+along with the reference to the classloader where the call was made.  Then this
+library finds the linker namespace (named `classloader-namespace`) that is
+associated with the given classloader, and tries to load the requested library
+from the namespace. The actual searching, loading, and linking of the library
+is performed by the dynamic linker.
+
+The linker namespace is created when an APK is loaded into the process, and is
+associated with the classloader that loaded the APK. The linker namespace is
+configured so that only the JNI libraries embedded in the APK is accessible
+from the namespace, thus preventing an APK from loading JNI libraries of other
+APKs.
+
+The linker namespace is also configured differently depending on other
+characteristics of the APK such as whether or not the APK is bundled with the
+platform. In case of the unbundled, i.e., downloaded or updated APK, only the
+public native libraries that is listed in `/system/etc/public.libraries.txt`
+are available from the platform, whereas in case of the bundled, all libraries
+under `/system/lib` are available (i.e. shared). In case when the unbundled
+app is from `/vendor` or `/product` partition, the app is additionally provided
+with the [VNDK-SP](https://source.android.com/devices/architecture/vndk#sp-hal)
+libraries. As the platform is getting modularized with
+[APEX](https://android.googlesource.com/platform/system/apex/+/refs/heads/master/docs/README.md),
+some libraries are no longer provided from platform, but from the APEXes which
+have their own linker namespaces. For example, ICU libraries `libicuuc.so` and
+`libicui18n.so` are from the runtime APEX.
+
+The list of public native libraries is not static. The default set of libraries
+are defined in AOSP, but partners can extend it to include their own libraries.
+Currently, following extensions are available:
+
+- `/vendor/etc/public.libraries.txt`: libraries in `/vendor/lib` that are
+specific to the underlying SoC, e.g. GPU, DSP, etc.
+- `/{system|product}/etc/public.libraries-<companyname>.txt`: libraries in
+`/{system|system}/lib` that a device manufacturer has newly added. The
+libraries should be named as `lib<name>.<companyname>.so` as in
+`libFoo.acme.so`.
+
+Note that, due to the naming constraint requiring `.<companyname>.so` suffix, it
+is prohibited for a device manufacturer to expose an AOSP-defined private
+library, e.g. libgui.so, libart.so, etc., to APKs.
+
+Lastly, libnativeloader is responsible for abstracting the two types of the
+dynamic linker interface: `libdl.so` and `libnativebridge.so`. The former is
+for non-translated, e.g. ARM-on-ARM, libraries, while the latter is for
+loading libraries in a translated environment such as ARM-on-x86.
+
+Implementation
+-------------------------------------------------------------------------------
+Implementation wise, libnativeloader consists of four parts:
+
+- `native_loader.cpp`
+- `library_namespaces.cpp`
+- `native_loader_namespace.cpp`
+- `public_libraries.cpp`
+
+`native_loader.cpp` implements the public interface of this library. It is just
+a thin wrapper around `library_namespaces.cpp` and `native_loader_namespace.cpp`.
+
+`library_namespaces.cpp` implements the singleton class `LibraryNamespaces` which
+is a manager-like entity that is responsible for creating and configuring
+linker namespaces and finding an already created linker namespace for a given
+classloader.
+
+`native_loader_namesapces.cpp` implements the class `NativeLoaderNamespace` that
+models a linker namespace. It's main job is to abstract the two types of the
+dynamic linker interface so that other parts of this library do not have to know
+the differences of the interfaces.
+
+`public_libraries.cpp` is responsible for reading `*.txt` files for the public
+native libraries from the various partitions. It can be considered as a part of
+`LibraryNamespaces` but is separated from it to hide the details of the parsing
+routines.
diff --git a/libnativeloader/library_namespaces.cpp b/libnativeloader/library_namespaces.cpp
index 3839a15..f7f972f 100644
--- a/libnativeloader/library_namespaces.cpp
+++ b/libnativeloader/library_namespaces.cpp
@@ -22,12 +22,13 @@
 #include <string>
 #include <vector>
 
-#include "android-base/file.h"
-#include "android-base/logging.h"
-#include "android-base/macros.h"
-#include "android-base/properties.h"
-#include "android-base/strings.h"
-#include "nativehelper/ScopedUtfChars.h"
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/macros.h>
+#include <android-base/properties.h>
+#include <android-base/strings.h>
+#include <nativehelper/ScopedUtfChars.h>
+
 #include "nativeloader/dlext_namespaces.h"
 #include "public_libraries.h"
 #include "utils.h"
@@ -41,8 +42,6 @@
 // vendor and system namespaces.
 constexpr const char* kVendorNamespaceName = "sphal";
 constexpr const char* kVndkNamespaceName = "vndk";
-constexpr const char* kDefaultNamespaceName = "default";
-constexpr const char* kPlatformNamespaceName = "platform";
 constexpr const char* kRuntimeNamespaceName = "runtime";
 
 // classloader-namespace is a linker namespace that is created for the loaded
@@ -167,34 +166,13 @@
 
   LOG_ALWAYS_FATAL_IF(found, "There is already a namespace associated with this classloader");
 
-  uint64_t namespace_type = ANDROID_NAMESPACE_TYPE_ISOLATED;
-  if (is_shared) {
-    namespace_type |= ANDROID_NAMESPACE_TYPE_SHARED;
-  }
-
-  if (target_sdk_version < 24) {
-    namespace_type |= ANDROID_NAMESPACE_TYPE_GREYLIST_ENABLED;
-  }
-
-  NativeLoaderNamespace* parent_ns = FindParentNamespaceByClassLoader(env, class_loader);
-
-  bool is_native_bridge = false;
-
-  if (parent_ns != nullptr) {
-    is_native_bridge = !parent_ns->is_android_namespace();
-  } else if (!library_path.empty()) {
-    is_native_bridge = NativeBridgeIsPathSupported(library_path.c_str());
-  }
-
   std::string system_exposed_libraries = default_public_libraries();
   const char* namespace_name = kClassloaderNamespaceName;
-  android_namespace_t* vndk_ns = nullptr;
+  bool unbundled_vendor_or_product_app = false;
   if ((apk_origin == APK_ORIGIN_VENDOR ||
        (apk_origin == APK_ORIGIN_PRODUCT && target_sdk_version > 29)) &&
       !is_shared) {
-    LOG_FATAL_IF(is_native_bridge,
-                 "Unbundled vendor / product apk must not use translated architecture");
-
+    unbundled_vendor_or_product_app = true;
     // For vendor / product apks, give access to the vendor / product lib even though
     // they are treated as unbundled; the libs and apks are still bundled
     // together in the vendor / product partition.
@@ -214,22 +192,12 @@
         origin_partition = "unknown";
         origin_lib_path = "";
     }
-
-    LOG_FATAL_IF(is_native_bridge, "Unbundled %s apk must not use translated architecture",
-                 origin_partition);
-
     library_path = library_path + ":" + origin_lib_path;
     permitted_path = permitted_path + ":" + origin_lib_path;
 
     // Also give access to LLNDK libraries since they are available to vendors
     system_exposed_libraries = system_exposed_libraries + ":" + llndk_libraries().c_str();
 
-    // Give access to VNDK-SP libraries from the 'vndk' namespace.
-    vndk_ns = android_get_exported_namespace(kVndkNamespaceName);
-    if (vndk_ns == nullptr) {
-      ALOGW("Cannot find \"%s\" namespace for %s apks", kVndkNamespaceName, origin_partition);
-    }
-
     // Different name is useful for debugging
     namespace_name = kVendorClassloaderNamespaceName;
     ALOGD("classloader namespace configured for unbundled %s apk. library_path=%s",
@@ -241,120 +209,56 @@
       system_exposed_libraries = system_exposed_libraries + ':' + extended_public_libraries();
     }
   }
-  std::string runtime_exposed_libraries = runtime_public_libraries();
 
-  NativeLoaderNamespace native_loader_ns;
-  if (!is_native_bridge) {
-    // The platform namespace is called "default" for binaries in /system and
-    // "platform" for those in the Runtime APEX. Try "platform" first since
-    // "default" always exists.
-    android_namespace_t* platform_ns = android_get_exported_namespace(kPlatformNamespaceName);
-    if (platform_ns == nullptr) {
-      platform_ns = android_get_exported_namespace(kDefaultNamespaceName);
-    }
-
-    android_namespace_t* android_parent_ns;
-    if (parent_ns != nullptr) {
-      android_parent_ns = parent_ns->get_android_ns();
-    } else {
-      // Fall back to the platform namespace if no parent is found.
-      android_parent_ns = platform_ns;
-    }
-
-    android_namespace_t* ns =
-        android_create_namespace(namespace_name, nullptr, library_path.c_str(), namespace_type,
-                                 permitted_path.c_str(), android_parent_ns);
-    if (ns == nullptr) {
-      *error_msg = dlerror();
-      return nullptr;
-    }
-
-    // Note that when vendor_ns is not configured this function will return nullptr
-    // and it will result in linking vendor_public_libraries_ to the default namespace
-    // which is expected behavior in this case.
-    android_namespace_t* vendor_ns = android_get_exported_namespace(kVendorNamespaceName);
-
-    android_namespace_t* runtime_ns = android_get_exported_namespace(kRuntimeNamespaceName);
-
-    if (!android_link_namespaces(ns, platform_ns, system_exposed_libraries.c_str())) {
-      *error_msg = dlerror();
-      return nullptr;
-    }
-
-    // Runtime apex does not exist in host, and under certain build conditions.
-    if (runtime_ns != nullptr) {
-      if (!android_link_namespaces(ns, runtime_ns, runtime_exposed_libraries.c_str())) {
-        *error_msg = dlerror();
-        return nullptr;
-      }
-    }
-
-    if (vndk_ns != nullptr && !vndksp_libraries().empty()) {
-      // vendor apks are allowed to use VNDK-SP libraries.
-      if (!android_link_namespaces(ns, vndk_ns, vndksp_libraries().c_str())) {
-        *error_msg = dlerror();
-        return nullptr;
-      }
-    }
-
-    if (!vendor_public_libraries().empty()) {
-      if (!android_link_namespaces(ns, vendor_ns, vendor_public_libraries().c_str())) {
-        *error_msg = dlerror();
-        return nullptr;
-      }
-    }
-
-    native_loader_ns = NativeLoaderNamespace(ns);
-  } else {
-    // Same functionality as in the branch above, but calling through native bridge.
-
-    native_bridge_namespace_t* platform_ns =
-        NativeBridgeGetExportedNamespace(kPlatformNamespaceName);
-    if (platform_ns == nullptr) {
-      platform_ns = NativeBridgeGetExportedNamespace(kDefaultNamespaceName);
-    }
-
-    native_bridge_namespace_t* native_bridge_parent_namespace;
-    if (parent_ns != nullptr) {
-      native_bridge_parent_namespace = parent_ns->get_native_bridge_ns();
-    } else {
-      native_bridge_parent_namespace = platform_ns;
-    }
-
-    native_bridge_namespace_t* ns =
-        NativeBridgeCreateNamespace(namespace_name, nullptr, library_path.c_str(), namespace_type,
-                                    permitted_path.c_str(), native_bridge_parent_namespace);
-    if (ns == nullptr) {
-      *error_msg = NativeBridgeGetError();
-      return nullptr;
-    }
-
-    native_bridge_namespace_t* vendor_ns = NativeBridgeGetExportedNamespace(kVendorNamespaceName);
-    native_bridge_namespace_t* runtime_ns = NativeBridgeGetExportedNamespace(kRuntimeNamespaceName);
-
-    if (!NativeBridgeLinkNamespaces(ns, platform_ns, system_exposed_libraries.c_str())) {
-      *error_msg = NativeBridgeGetError();
-      return nullptr;
-    }
-
-    // Runtime apex does not exist in host, and under certain build conditions.
-    if (runtime_ns != nullptr) {
-      if (!NativeBridgeLinkNamespaces(ns, runtime_ns, runtime_exposed_libraries.c_str())) {
-        *error_msg = NativeBridgeGetError();
-        return nullptr;
-      }
-    }
-    if (!vendor_public_libraries().empty()) {
-      if (!NativeBridgeLinkNamespaces(ns, vendor_ns, vendor_public_libraries().c_str())) {
-        *error_msg = NativeBridgeGetError();
-        return nullptr;
-      }
-    }
-
-    native_loader_ns = NativeLoaderNamespace(ns);
+  // Create the app namespace
+  NativeLoaderNamespace* parent_ns = FindParentNamespaceByClassLoader(env, class_loader);
+  auto app_ns =
+      NativeLoaderNamespace::Create(namespace_name, library_path, permitted_path, parent_ns,
+                                    is_shared, target_sdk_version < 24 /* is_greylist_enabled */);
+  if (app_ns.IsNil()) {
+    *error_msg = app_ns.GetError();
+    return nullptr;
   }
 
-  namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), native_loader_ns));
+  // ... and link to other namespaces to allow access to some public libraries
+  bool is_bridged = app_ns.IsBridged();
+
+  auto platform_ns = NativeLoaderNamespace::GetPlatformNamespace(is_bridged);
+  if (!app_ns.Link(platform_ns, system_exposed_libraries)) {
+    *error_msg = app_ns.GetError();
+    return nullptr;
+  }
+
+  auto runtime_ns = NativeLoaderNamespace::GetExportedNamespace(kRuntimeNamespaceName, is_bridged);
+  // Runtime apex does not exist in host, and under certain build conditions.
+  if (!runtime_ns.IsNil()) {
+    if (!app_ns.Link(runtime_ns, runtime_public_libraries())) {
+      *error_msg = app_ns.GetError();
+      return nullptr;
+    }
+  }
+
+  // Give access to VNDK-SP libraries from the 'vndk' namespace.
+  if (unbundled_vendor_or_product_app && !vndksp_libraries().empty()) {
+    auto vndk_ns = NativeLoaderNamespace::GetExportedNamespace(kVndkNamespaceName, is_bridged);
+    if (!vndk_ns.IsNil() && !app_ns.Link(vndk_ns, vndksp_libraries())) {
+      *error_msg = app_ns.GetError();
+      return nullptr;
+    }
+  }
+
+  // Note that when vendor_ns is not configured, vendor_ns.IsNil() will be true
+  // and it will result in linking to the default namespace which is expected
+  // behavior in this case.
+  if (!vendor_public_libraries().empty()) {
+    auto vendor_ns = NativeLoaderNamespace::GetExportedNamespace(kVendorNamespaceName, is_bridged);
+    if (!app_ns.Link(vendor_ns, vendor_public_libraries())) {
+      *error_msg = dlerror();
+      return nullptr;
+    }
+  }
+
+  namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), app_ns));
 
   return &(namespaces_.back().second);
 }
diff --git a/libnativeloader/library_namespaces.h b/libnativeloader/library_namespaces.h
index 103cfac..fd46cdc 100644
--- a/libnativeloader/library_namespaces.h
+++ b/libnativeloader/library_namespaces.h
@@ -25,8 +25,7 @@
 #include <list>
 #include <string>
 
-#include "jni.h"
-#include "utils.h"
+#include <jni.h>
 
 namespace android::nativeloader {
 
diff --git a/libnativeloader/native_loader.cpp b/libnativeloader/native_loader.cpp
index eeee077..0c29324 100644
--- a/libnativeloader/native_loader.cpp
+++ b/libnativeloader/native_loader.cpp
@@ -14,9 +14,10 @@
  * limitations under the License.
  */
 
-#include "nativeloader/native_loader.h"
 #define LOG_TAG "nativeloader"
 
+#include "nativeloader/native_loader.h"
+
 #include <dlfcn.h>
 #include <sys/types.h>
 
@@ -25,16 +26,17 @@
 #include <string>
 #include <vector>
 
-#include "android-base/file.h"
-#include "android-base/macros.h"
-#include "android-base/strings.h"
+#include <android-base/file.h>
+#include <android-base/macros.h>
+#include <android-base/strings.h>
+#include <nativebridge/native_bridge.h>
+#include <nativehelper/ScopedUtfChars.h>
+
 #ifdef __ANDROID__
+#include <log/log.h>
 #include "library_namespaces.h"
-#include "log/log.h"
 #include "nativeloader/dlext_namespaces.h"
 #endif
-#include "nativebridge/native_bridge.h"
-#include "nativehelper/ScopedUtfChars.h"
 
 namespace android {
 
@@ -220,25 +222,12 @@
 #if defined(__ANDROID__)
 void* OpenNativeLibraryInNamespace(NativeLoaderNamespace* ns, const char* path,
                                    bool* needs_native_bridge, char** error_msg) {
-  if (ns->is_android_namespace()) {
-    android_dlextinfo extinfo;
-    extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
-    extinfo.library_namespace = ns->get_android_ns();
-
-    void* handle = android_dlopen_ext(path, RTLD_NOW, &extinfo);
-    if (handle == nullptr) {
-      *error_msg = strdup(dlerror());
-    }
-    *needs_native_bridge = false;
-    return handle;
-  } else {
-    void* handle = NativeBridgeLoadLibraryExt(path, RTLD_NOW, ns->get_native_bridge_ns());
-    if (handle == nullptr) {
-      *error_msg = strdup(NativeBridgeGetError());
-    }
-    *needs_native_bridge = true;
-    return handle;
+  void* handle = ns->Load(path);
+  if (handle == nullptr) {
+    *error_msg = ns->GetError();
   }
+  *needs_native_bridge = ns->IsBridged();
+  return handle;
 }
 
 // native_bridge_namespaces are not supported for callers of this function.
@@ -247,10 +236,9 @@
 android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
   std::lock_guard<std::mutex> guard(g_namespaces_mutex);
   NativeLoaderNamespace* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
-  if (ns != nullptr) {
-    return ns->is_android_namespace() ? ns->get_android_ns() : nullptr;
+  if (ns != nullptr && !ns->IsBridged()) {
+    return ns->ToRawAndroidNamespace();
   }
-
   return nullptr;
 }
 
diff --git a/libnativeloader/native_loader_namespace.cpp b/libnativeloader/native_loader_namespace.cpp
new file mode 100644
index 0000000..90f730c
--- /dev/null
+++ b/libnativeloader/native_loader_namespace.cpp
@@ -0,0 +1,130 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "nativeloader"
+
+#include "native_loader_namespace.h"
+
+#include <dlfcn.h>
+
+#include <functional>
+
+#include <android-base/strings.h>
+#include <log/log.h>
+#include <nativebridge/native_bridge.h>
+
+#include "nativeloader/dlext_namespaces.h"
+
+namespace android {
+
+namespace {
+
+constexpr const char* kDefaultNamespaceName = "default";
+constexpr const char* kPlatformNamespaceName = "platform";
+
+}  // namespace
+
+NativeLoaderNamespace NativeLoaderNamespace::GetExportedNamespace(const std::string& name,
+                                                                  bool is_bridged) {
+  if (!is_bridged) {
+    return NativeLoaderNamespace(name, android_get_exported_namespace(name.c_str()));
+  } else {
+    return NativeLoaderNamespace(name, NativeBridgeGetExportedNamespace(name.c_str()));
+  }
+}
+
+char* NativeLoaderNamespace::GetError() const {
+  if (!IsBridged()) {
+    return strdup(dlerror());
+  } else {
+    return strdup(NativeBridgeGetError());
+  }
+}
+
+// The platform namespace is called "default" for binaries in /system and
+// "platform" for those in the Runtime APEX. Try "platform" first since
+// "default" always exists.
+NativeLoaderNamespace NativeLoaderNamespace::GetPlatformNamespace(bool is_bridged) {
+  NativeLoaderNamespace ns = GetExportedNamespace(kPlatformNamespaceName, is_bridged);
+  if (ns.IsNil()) {
+    ns = GetExportedNamespace(kDefaultNamespaceName, is_bridged);
+  }
+  return ns;
+}
+
+NativeLoaderNamespace NativeLoaderNamespace::Create(const std::string& name,
+                                                    const std::string& search_paths,
+                                                    const std::string& permitted_paths,
+                                                    const NativeLoaderNamespace* parent,
+                                                    bool is_shared, bool is_greylist_enabled) {
+  bool is_bridged = false;
+  if (parent != nullptr) {
+    is_bridged = parent->IsBridged();
+  } else if (!search_paths.empty()) {
+    is_bridged = NativeBridgeIsPathSupported(search_paths.c_str());
+  }
+
+  // Fall back to the platform namespace if no parent is set.
+  const NativeLoaderNamespace& effective_parent =
+      parent != nullptr ? *parent : GetPlatformNamespace(is_bridged);
+
+  uint64_t type = ANDROID_NAMESPACE_TYPE_ISOLATED;
+  if (is_shared) {
+    type |= ANDROID_NAMESPACE_TYPE_SHARED;
+  }
+  if (is_greylist_enabled) {
+    type |= ANDROID_NAMESPACE_TYPE_GREYLIST_ENABLED;
+  }
+
+  if (!is_bridged) {
+    android_namespace_t* raw =
+        android_create_namespace(name.c_str(), nullptr, search_paths.c_str(), type,
+                                 permitted_paths.c_str(), effective_parent.ToRawAndroidNamespace());
+    return NativeLoaderNamespace(name, raw);
+  } else {
+    native_bridge_namespace_t* raw = NativeBridgeCreateNamespace(
+        name.c_str(), nullptr, search_paths.c_str(), type, permitted_paths.c_str(),
+        effective_parent.ToRawNativeBridgeNamespace());
+    return NativeLoaderNamespace(name, raw);
+  }
+}
+
+bool NativeLoaderNamespace::Link(const NativeLoaderNamespace& target,
+                                 const std::string& shared_libs) const {
+  LOG_ALWAYS_FATAL_IF(shared_libs.empty(), "empty share lib when linking %s to %s",
+                      this->name().c_str(), target.name().c_str());
+  if (!IsBridged()) {
+    return android_link_namespaces(this->ToRawAndroidNamespace(), target.ToRawAndroidNamespace(),
+                                   shared_libs.c_str());
+  } else {
+    return NativeBridgeLinkNamespaces(this->ToRawNativeBridgeNamespace(),
+                                      target.ToRawNativeBridgeNamespace(), shared_libs.c_str());
+  }
+}
+
+void* NativeLoaderNamespace::Load(const std::string& lib_name) const {
+  if (!IsBridged()) {
+    android_dlextinfo extinfo;
+    extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
+    extinfo.library_namespace = this->ToRawAndroidNamespace();
+    return android_dlopen_ext(lib_name.c_str(), RTLD_NOW, &extinfo);
+  } else {
+    return NativeBridgeLoadLibraryExt(lib_name.c_str(), RTLD_NOW,
+                                      this->ToRawNativeBridgeNamespace());
+  }
+}
+
+}  // namespace android
diff --git a/libnativeloader/native_loader_namespace.h b/libnativeloader/native_loader_namespace.h
index b983a2d..1575f8c 100644
--- a/libnativeloader/native_loader_namespace.h
+++ b/libnativeloader/native_loader_namespace.h
@@ -16,13 +16,14 @@
 #pragma once
 #if defined(__ANDROID__)
 
-#include <dlfcn.h>
+#include <string>
+#include <variant>
+#include <vector>
 
-#include "android-base/logging.h"
-#include "android/dlext.h"
-#include "log/log.h"
-#include "nativebridge/native_bridge.h"
-#include "utils.h"
+#include <android-base/logging.h>
+#include <android/dlext.h>
+#include <log/log.h>
+#include <nativebridge/native_bridge.h>
 
 namespace android {
 
@@ -31,34 +32,40 @@
 // x86). Instances of this class are managed by LibraryNamespaces object.
 struct NativeLoaderNamespace {
  public:
-  NativeLoaderNamespace() : android_ns_(nullptr), native_bridge_ns_(nullptr) {}
-
-  explicit NativeLoaderNamespace(android_namespace_t* ns)
-      : android_ns_(ns), native_bridge_ns_(nullptr) {}
-
-  explicit NativeLoaderNamespace(native_bridge_namespace_t* ns)
-      : android_ns_(nullptr), native_bridge_ns_(ns) {}
+  // TODO(return with errors)
+  static NativeLoaderNamespace Create(const std::string& name, const std::string& search_paths,
+                                      const std::string& permitted_paths,
+                                      const NativeLoaderNamespace* parent, bool is_shared,
+                                      bool is_greylist_enabled);
 
   NativeLoaderNamespace(NativeLoaderNamespace&&) = default;
   NativeLoaderNamespace(const NativeLoaderNamespace&) = default;
   NativeLoaderNamespace& operator=(const NativeLoaderNamespace&) = default;
 
-  android_namespace_t* get_android_ns() const {
-    CHECK(native_bridge_ns_ == nullptr);
-    return android_ns_;
+  android_namespace_t* ToRawAndroidNamespace() const { return std::get<0>(raw_); }
+  native_bridge_namespace_t* ToRawNativeBridgeNamespace() const { return std::get<1>(raw_); }
+
+  std::string name() const { return name_; }
+  bool IsBridged() const { return raw_.index() == 1; }
+  bool IsNil() const {
+    return IsBridged() ? std::get<1>(raw_) == nullptr : std::get<0>(raw_) == nullptr;
   }
 
-  native_bridge_namespace_t* get_native_bridge_ns() const {
-    CHECK(android_ns_ == nullptr);
-    return native_bridge_ns_;
-  }
+  bool Link(const NativeLoaderNamespace& target, const std::string& shared_libs) const;
+  void* Load(const std::string& lib_name) const;
+  char* GetError() const;
 
-  bool is_android_namespace() const { return native_bridge_ns_ == nullptr; }
+  static NativeLoaderNamespace GetExportedNamespace(const std::string& name, bool is_bridged);
+  static NativeLoaderNamespace GetPlatformNamespace(bool is_bridged);
 
  private:
-  // Only one of them can be not null
-  android_namespace_t* android_ns_;
-  native_bridge_namespace_t* native_bridge_ns_;
+  explicit NativeLoaderNamespace(const std::string& name, android_namespace_t* ns)
+      : name_(name), raw_(ns) {}
+  explicit NativeLoaderNamespace(const std::string& name, native_bridge_namespace_t* ns)
+      : name_(name), raw_(ns) {}
+
+  std::string name_;
+  std::variant<android_namespace_t*, native_bridge_namespace_t*> raw_;
 };
 
 }  // namespace android
diff --git a/libnativeloader/public_libraries.cpp b/libnativeloader/public_libraries.cpp
index c473f2c..c205eb1 100644
--- a/libnativeloader/public_libraries.cpp
+++ b/libnativeloader/public_libraries.cpp
@@ -14,19 +14,21 @@
  * limitations under the License.
  */
 
-#include "public_libraries.h"
 #define LOG_TAG "nativeloader"
 
+#include "public_libraries.h"
+
 #include <dirent.h>
 
 #include <algorithm>
 #include <memory>
 
-#include "android-base/file.h"
-#include "android-base/logging.h"
-#include "android-base/properties.h"
-#include "android-base/strings.h"
-#include "log/log.h"
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/strings.h>
+#include <log/log.h>
+
 #include "utils.h"
 
 namespace android::nativeloader {
@@ -68,6 +70,16 @@
   return "";
 }
 
+// For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
+// variable to add libraries to the list. This is intended for platform tests only.
+std::string additional_public_libraries() {
+  if (debuggable()) {
+    const char* val = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
+    return val ? val : "";
+  }
+  return "";
+}
+
 void InsertVndkVersionStr(std::string* file_name) {
   CHECK(file_name != nullptr);
   size_t insert_pos = file_name->find_last_of(".");
@@ -171,130 +183,119 @@
   }
 }
 
-}  // namespace
+static std::string InitDefaultPublicLibraries() {
+  std::string config_file = root_dir() + kDefaultPublicLibrariesFile;
+  std::vector<std::string> sonames;
+  std::string error_msg;
+  LOG_ALWAYS_FATAL_IF(!ReadConfig(config_file, &sonames, always_true, &error_msg),
+                      "Error reading public native library list from \"%s\": %s",
+                      config_file.c_str(), error_msg.c_str());
 
-const std::string& default_public_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    std::string config_file = root_dir() + kDefaultPublicLibrariesFile;
-    std::vector<std::string> sonames;
-    std::string error_msg;
-    LOG_ALWAYS_FATAL_IF(!ReadConfig(config_file, &sonames, always_true, &error_msg),
-                        "Error reading public native library list from \"%s\": %s",
-                        config_file.c_str(), error_msg.c_str());
+  std::string additional_libs = additional_public_libraries();
+  if (!additional_libs.empty()) {
+    auto vec = base::Split(additional_libs, ":");
+    std::copy(vec.begin(), vec.end(), std::back_inserter(sonames));
+  }
 
-    // For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
-    // variable to add libraries to the list. This is intended for platform tests only.
-    if (debuggable()) {
-      const char* additional_libs = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
-      if (additional_libs != nullptr && additional_libs[0] != '\0') {
-        std::vector<std::string> additional_libs_vector = base::Split(additional_libs, ":");
-        std::copy(additional_libs_vector.begin(), additional_libs_vector.end(),
-                  std::back_inserter(sonames));
-      }
+  // Remove the public libs in the runtime namespace.
+  // These libs are listed in public.android.txt, but we don't want the rest of android
+  // in default namespace to dlopen the libs.
+  // For example, libicuuc.so is exposed to classloader namespace from runtime namespace.
+  // Unfortunately, it does not have stable C symbols, and default namespace should only use
+  // stable symbols in libandroidicu.so. http://b/120786417
+  for (const std::string& lib_name : kRuntimePublicLibraries) {
+    std::string path(kRuntimeApexLibPath);
+    path.append("/").append(lib_name);
+
+    struct stat s;
+    // Do nothing if the path in /apex does not exist.
+    // Runtime APEX must be mounted since libnativeloader is in the same APEX
+    if (stat(path.c_str(), &s) != 0) {
+      continue;
     }
 
-    // Remove the public libs in the runtime namespace.
-    // These libs are listed in public.android.txt, but we don't want the rest of android
-    // in default namespace to dlopen the libs.
-    // For example, libicuuc.so is exposed to classloader namespace from runtime namespace.
-    // Unfortunately, it does not have stable C symbols, and default namespace should only use
-    // stable symbols in libandroidicu.so. http://b/120786417
-    for (const std::string& lib_name : kRuntimePublicLibraries) {
-      std::string path(kRuntimeApexLibPath);
-      path.append("/").append(lib_name);
-
-      struct stat s;
-      // Do nothing if the path in /apex does not exist.
-      // Runtime APEX must be mounted since libnativeloader is in the same APEX
-      if (stat(path.c_str(), &s) != 0) {
-        continue;
-      }
-
-      auto it = std::find(sonames.begin(), sonames.end(), lib_name);
-      if (it != sonames.end()) {
-        sonames.erase(it);
-      }
+    auto it = std::find(sonames.begin(), sonames.end(), lib_name);
+    if (it != sonames.end()) {
+      sonames.erase(it);
     }
-    list = android::base::Join(sonames, ':');
-    cached = true;
+  }
+  return android::base::Join(sonames, ':');
+}
+
+static std::string InitRuntimePublicLibraries() {
+  CHECK(sizeof(kRuntimePublicLibraries) > 0);
+  std::string list = android::base::Join(kRuntimePublicLibraries, ":");
+
+  std::string additional_libs = additional_public_libraries();
+  if (!additional_libs.empty()) {
+    list = list + ':' + additional_libs;
   }
   return list;
 }
 
-const std::string& runtime_public_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    list = android::base::Join(kRuntimePublicLibraries, ":");
-    // For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
-    // variable to add libraries to the list. This is intended for platform tests only.
-    if (debuggable()) {
-      const char* additional_libs = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
-      if (additional_libs != nullptr && additional_libs[0] != '\0') {
-        list = list + ':' + additional_libs;
-      }
-    }
-  }
-  return list;
-}
-
-const std::string& vendor_public_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    // This file is optional, quietly ignore if the file does not exist.
-    std::vector<std::string> sonames;
-    ReadConfig(kVendorPublicLibrariesFile, &sonames, always_true, nullptr);
-    list = android::base::Join(sonames, ':');
-    cached = true;
-  }
-  return list;
+static std::string InitVendorPublicLibraries() {
+  // This file is optional, quietly ignore if the file does not exist.
+  std::vector<std::string> sonames;
+  ReadConfig(kVendorPublicLibrariesFile, &sonames, always_true, nullptr);
+  return android::base::Join(sonames, ':');
 }
 
 // read /system/etc/public.libraries-<companyname>.txt and
 // /product/etc/public.libraries-<companyname>.txt which contain partner defined
 // system libs that are exposed to apps. The libs in the txt files must be
 // named as lib<name>.<companyname>.so.
+static std::string InitExtendedPublicLibraries() {
+  std::vector<std::string> sonames;
+  ReadExtensionLibraries("/system/etc", &sonames);
+  ReadExtensionLibraries("/product/etc", &sonames);
+  return android::base::Join(sonames, ':');
+}
+
+static std::string InitLlndkLibraries() {
+  std::string config_file = kLlndkLibrariesFile;
+  InsertVndkVersionStr(&config_file);
+  std::vector<std::string> sonames;
+  ReadConfig(config_file, &sonames, always_true, nullptr);
+  return android::base::Join(sonames, ':');
+}
+
+static std::string InitVndkspLibraries() {
+  std::string config_file = kVndkLibrariesFile;
+  InsertVndkVersionStr(&config_file);
+  std::vector<std::string> sonames;
+  ReadConfig(config_file, &sonames, always_true, nullptr);
+  return android::base::Join(sonames, ':');
+}
+
+}  // namespace
+
+const std::string& default_public_libraries() {
+  static std::string list = InitDefaultPublicLibraries();
+  return list;
+}
+
+const std::string& runtime_public_libraries() {
+  static std::string list = InitRuntimePublicLibraries();
+  return list;
+}
+
+const std::string& vendor_public_libraries() {
+  static std::string list = InitVendorPublicLibraries();
+  return list;
+}
+
 const std::string& extended_public_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    std::vector<std::string> sonames;
-    ReadExtensionLibraries("/system/etc", &sonames);
-    ReadExtensionLibraries("/product/etc", &sonames);
-    list = android::base::Join(sonames, ':');
-    cached = true;
-  }
+  static std::string list = InitExtendedPublicLibraries();
   return list;
 }
 
 const std::string& llndk_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    std::string config_file = kLlndkLibrariesFile;
-    InsertVndkVersionStr(&config_file);
-    std::vector<std::string> sonames;
-    ReadConfig(config_file, &sonames, always_true, nullptr);
-    list = android::base::Join(sonames, ':');
-    cached = true;
-  }
+  static std::string list = InitLlndkLibraries();
   return list;
 }
 
 const std::string& vndksp_libraries() {
-  static bool cached = false;
-  static std::string list;
-  if (!cached) {
-    std::string config_file = kVndkLibrariesFile;
-    InsertVndkVersionStr(&config_file);
-    std::vector<std::string> sonames;
-    ReadConfig(config_file, &sonames, always_true, nullptr);
-    list = android::base::Join(sonames, ':');
-    cached = true;
-  }
+  static std::string list = InitVndkspLibraries();
   return list;
 }
 
diff --git a/libprocessgroup/Android.bp b/libprocessgroup/Android.bp
index 78a02e5..0207a75 100644
--- a/libprocessgroup/Android.bp
+++ b/libprocessgroup/Android.bp
@@ -32,6 +32,8 @@
     shared_libs: [
         "libbase",
         "libcgrouprc",
+    ],
+    static_libs: [
         "libjsoncpp",
     ],
     // for cutils/android_filesystem_config.h
diff --git a/libsync/Android.bp b/libsync/Android.bp
index e56f8ba..c996e1b 100644
--- a/libsync/Android.bp
+++ b/libsync/Android.bp
@@ -23,6 +23,7 @@
 cc_library {
     name: "libsync",
     recovery_available: true,
+    native_bridge_supported: true,
     defaults: ["libsync_defaults"],
 }
 
diff --git a/libutils/Looper.cpp b/libutils/Looper.cpp
index 2d696eb..14e3e35 100644
--- a/libutils/Looper.cpp
+++ b/libutils/Looper.cpp
@@ -14,7 +14,9 @@
 #define DEBUG_CALLBACKS 0
 
 #include <utils/Looper.h>
+
 #include <sys/eventfd.h>
+#include <cinttypes>
 
 namespace android {
 
diff --git a/libziparchive/include/ziparchive/zip_archive.h b/libziparchive/include/ziparchive/zip_archive.h
index 6e837a4..7eead7e 100644
--- a/libziparchive/include/ziparchive/zip_archive.h
+++ b/libziparchive/include/ziparchive/zip_archive.h
@@ -177,7 +177,10 @@
  *
  * Returns 0 on success and negative values on failure.
  */
-// TODO: switch these ZipStrings to std::string_view.
+int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
+                       const std::string_view optional_prefix = "",
+                       const std::string_view optional_suffix = "");
+// TODO: remove this.
 int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
                        const ZipString* optional_prefix, const ZipString* optional_suffix);
 
diff --git a/libziparchive/unzip.cpp b/libziparchive/unzip.cpp
index c6def73..3a3a694 100644
--- a/libziparchive/unzip.cpp
+++ b/libziparchive/unzip.cpp
@@ -249,7 +249,7 @@
   // libziparchive iteration order doesn't match the central directory.
   // We could sort, but that would cost extra and wouldn't match either.
   void* cookie;
-  int err = StartIteration(zah, &cookie, nullptr, nullptr);
+  int err = StartIteration(zah, &cookie);
   if (err != 0) {
     error(1, 0, "couldn't iterate %s: %s", archive_name, ErrorCodeString(err));
   }
diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index 2bd8fb9..ac3e236 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -689,54 +689,59 @@
 }
 
 struct IterationHandle {
-  uint32_t position;
-  // TODO: switch these to std::string now that Windows uses libc++ too.
-  ZipString prefix;
-  ZipString suffix;
   ZipArchive* archive;
 
-  IterationHandle(const ZipString* in_prefix, const ZipString* in_suffix) {
-    if (in_prefix) {
-      uint8_t* name_copy = new uint8_t[in_prefix->name_length];
-      memcpy(name_copy, in_prefix->name, in_prefix->name_length);
-      prefix.name = name_copy;
-      prefix.name_length = in_prefix->name_length;
-    } else {
-      prefix.name = NULL;
-      prefix.name_length = 0;
-    }
-    if (in_suffix) {
-      uint8_t* name_copy = new uint8_t[in_suffix->name_length];
-      memcpy(name_copy, in_suffix->name, in_suffix->name_length);
-      suffix.name = name_copy;
-      suffix.name_length = in_suffix->name_length;
-    } else {
-      suffix.name = NULL;
-      suffix.name_length = 0;
-    }
-  }
+  std::string prefix_holder;
+  ZipString prefix;
 
-  ~IterationHandle() {
-    delete[] prefix.name;
-    delete[] suffix.name;
-  }
+  std::string suffix_holder;
+  ZipString suffix;
+
+  uint32_t position = 0;
+
+  IterationHandle(ZipArchive* archive, const std::string_view in_prefix,
+                  const std::string_view in_suffix)
+      : archive(archive),
+        prefix_holder(in_prefix),
+        prefix(prefix_holder),
+        suffix_holder(in_suffix),
+        suffix(suffix_holder) {}
 };
 
 int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
-                       const ZipString* optional_prefix, const ZipString* optional_suffix) {
+                       const std::string_view optional_prefix,
+                       const std::string_view optional_suffix) {
   if (archive == NULL || archive->hash_table == NULL) {
     ALOGW("Zip: Invalid ZipArchiveHandle");
     return kInvalidHandle;
   }
 
-  IterationHandle* cookie = new IterationHandle(optional_prefix, optional_suffix);
-  cookie->position = 0;
-  cookie->archive = archive;
+  if (optional_prefix.size() > static_cast<size_t>(UINT16_MAX) ||
+      optional_suffix.size() > static_cast<size_t>(UINT16_MAX)) {
+    ALOGW("Zip: prefix/suffix too long");
+    return kInvalidEntryName;
+  }
 
-  *cookie_ptr = cookie;
+  *cookie_ptr = new IterationHandle(archive, optional_prefix, optional_suffix);
   return 0;
 }
 
+// TODO: remove this.
+int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
+                       const ZipString* optional_prefix, const ZipString* optional_suffix) {
+  std::string prefix;
+  if (optional_prefix) {
+    prefix = std::string(reinterpret_cast<const char*>(optional_prefix->name),
+                         optional_prefix->name_length);
+  }
+  std::string suffix;
+  if (optional_suffix) {
+    suffix = std::string(reinterpret_cast<const char*>(optional_suffix->name),
+                         optional_suffix->name_length);
+  }
+  return StartIteration(archive, cookie_ptr, prefix.c_str(), suffix.c_str());
+}
+
 void EndIteration(void* cookie) {
   delete reinterpret_cast<IterationHandle*>(cookie);
 }
diff --git a/libziparchive/zip_archive_benchmark.cpp b/libziparchive/zip_archive_benchmark.cpp
index 52166a4..434f2e1 100644
--- a/libziparchive/zip_archive_benchmark.cpp
+++ b/libziparchive/zip_archive_benchmark.cpp
@@ -75,7 +75,7 @@
 
   while (state.KeepRunning()) {
     OpenArchive(temp_file->path, &handle);
-    StartIteration(handle, &iteration_cookie, nullptr, nullptr);
+    StartIteration(handle, &iteration_cookie);
     while (Next(iteration_cookie, &data, &name) == 0) {
     }
     EndIteration(iteration_cookie);
diff --git a/libziparchive/zip_archive_test.cc b/libziparchive/zip_archive_test.cc
index cfbce1c..993c975 100644
--- a/libziparchive/zip_archive_test.cc
+++ b/libziparchive/zip_archive_test.cc
@@ -107,7 +107,7 @@
   close(fd);
 }
 
-static void AssertIterationOrder(const ZipString* prefix, const ZipString* suffix,
+static void AssertIterationOrder(const std::string_view prefix, const std::string_view suffix,
                                  const std::vector<std::string>& expected_names_sorted) {
   ZipArchiveHandle handle;
   ASSERT_EQ(0, OpenArchiveWrapper(kValidZip, &handle));
@@ -137,30 +137,26 @@
   static const std::vector<std::string> kExpectedMatchesSorted = {"a.txt", "b.txt", "b/", "b/c.txt",
                                                                   "b/d.txt"};
 
-  AssertIterationOrder(nullptr, nullptr, kExpectedMatchesSorted);
+  AssertIterationOrder("", "", kExpectedMatchesSorted);
 }
 
 TEST(ziparchive, IterationWithPrefix) {
-  ZipString prefix("b/");
   static const std::vector<std::string> kExpectedMatchesSorted = {"b/", "b/c.txt", "b/d.txt"};
 
-  AssertIterationOrder(&prefix, nullptr, kExpectedMatchesSorted);
+  AssertIterationOrder("b/", "", kExpectedMatchesSorted);
 }
 
 TEST(ziparchive, IterationWithSuffix) {
-  ZipString suffix(".txt");
   static const std::vector<std::string> kExpectedMatchesSorted = {"a.txt", "b.txt", "b/c.txt",
                                                                   "b/d.txt"};
 
-  AssertIterationOrder(nullptr, &suffix, kExpectedMatchesSorted);
+  AssertIterationOrder("", ".txt", kExpectedMatchesSorted);
 }
 
 TEST(ziparchive, IterationWithPrefixAndSuffix) {
-  ZipString prefix("b");
-  ZipString suffix(".txt");
   static const std::vector<std::string> kExpectedMatchesSorted = {"b.txt", "b/c.txt", "b/d.txt"};
 
-  AssertIterationOrder(&prefix, &suffix, kExpectedMatchesSorted);
+  AssertIterationOrder("b", ".txt", kExpectedMatchesSorted);
 }
 
 TEST(ziparchive, IterationWithBadPrefixAndSuffix) {
@@ -168,9 +164,7 @@
   ASSERT_EQ(0, OpenArchiveWrapper(kValidZip, &handle));
 
   void* iteration_cookie;
-  ZipString prefix("x");
-  ZipString suffix("y");
-  ASSERT_EQ(0, StartIteration(handle, &iteration_cookie, &prefix, &suffix));
+  ASSERT_EQ(0, StartIteration(handle, &iteration_cookie, "x", "y"));
 
   ZipEntry data;
   ZipString name;
@@ -228,7 +222,7 @@
   ASSERT_EQ(0, OpenArchiveWrapper("declaredlength.zip", &handle));
 
   void* iteration_cookie;
-  ASSERT_EQ(0, StartIteration(handle, &iteration_cookie, nullptr, nullptr));
+  ASSERT_EQ(0, StartIteration(handle, &iteration_cookie));
 
   ZipString name;
   ZipEntry data;
diff --git a/logd/tests/Android.bp b/logd/tests/Android.bp
index 83a194f..d39da8a 100644
--- a/logd/tests/Android.bp
+++ b/logd/tests/Android.bp
@@ -35,12 +35,12 @@
 
     srcs: ["logd_test.cpp"],
 
-    shared_libs: [
+    static_libs: [
         "libbase",
         "libcutils",
         "libselinux",
+        "liblog",
     ],
-    static_libs: ["liblog"],
 }
 
 // Build tests for the logger. Run with:
diff --git a/usbd/usbd.cpp b/usbd/usbd.cpp
index 41cd8dd..191fb92 100644
--- a/usbd/usbd.cpp
+++ b/usbd/usbd.cpp
@@ -22,15 +22,20 @@
 #include <android-base/properties.h>
 #include <android/hardware/usb/gadget/1.0/IUsbGadget.h>
 
+#include <hidl/HidlTransportSupport.h>
+
 #define PERSISTENT_USB_CONFIG "persist.sys.usb.config"
 
 using android::base::GetProperty;
 using android::base::SetProperty;
+using android::hardware::configureRpcThreadpool;
 using android::hardware::usb::gadget::V1_0::GadgetFunction;
 using android::hardware::usb::gadget::V1_0::IUsbGadget;
 using android::hardware::Return;
 
 int main(int /*argc*/, char** /*argv*/) {
+    configureRpcThreadpool(1, true /*callerWillJoin*/);
+
     android::sp<IUsbGadget> gadget = IUsbGadget::getService();
     Return<void> ret;