diff --git a/adb/client/adb_install.cpp b/adb/client/adb_install.cpp
index 16fa215..f1f080a 100644
--- a/adb/client/adb_install.cpp
+++ b/adb/client/adb_install.cpp
@@ -409,7 +409,8 @@
             android::base::EndsWithIgnoreCase(file, ".dm") ||
             android::base::EndsWithIgnoreCase(file, ".fsv_sig")) {
             struct stat sb;
-            if (stat(file, &sb) != -1) total_size += sb.st_size;
+            if (stat(file, &sb) == -1) perror_exit("failed to stat \"%s\"", file);
+            total_size += sb.st_size;
             first_apk = i;
         } else {
             break;
@@ -459,13 +460,13 @@
     }
 
     // Valid session, now stream the APKs
-    int success = 1;
+    bool success = true;
     for (int i = first_apk; i < argc; i++) {
         const char* file = argv[i];
         struct stat sb;
         if (stat(file, &sb) == -1) {
-            fprintf(stderr, "adb: failed to stat %s: %s\n", file, strerror(errno));
-            success = 0;
+            fprintf(stderr, "adb: failed to stat \"%s\": %s\n", file, strerror(errno));
+            success = false;
             goto finalize_session;
         }
 
@@ -476,8 +477,8 @@
 
         unique_fd local_fd(adb_open(file, O_RDONLY | O_CLOEXEC));
         if (local_fd < 0) {
-            fprintf(stderr, "adb: failed to open %s: %s\n", file, strerror(errno));
-            success = 0;
+            fprintf(stderr, "adb: failed to open \"%s\": %s\n", file, strerror(errno));
+            success = false;
             goto finalize_session;
         }
 
@@ -485,7 +486,7 @@
         unique_fd remote_fd(adb_connect(cmd, &error));
         if (remote_fd < 0) {
             fprintf(stderr, "adb: connect error for write: %s\n", error.c_str());
-            success = 0;
+            success = false;
             goto finalize_session;
         }
 
@@ -493,15 +494,15 @@
         read_status_line(remote_fd.get(), buf, sizeof(buf));
 
         if (strncmp("Success", buf, 7)) {
-            fprintf(stderr, "adb: failed to write %s\n", file);
+            fprintf(stderr, "adb: failed to write \"%s\"\n", file);
             fputs(buf, stderr);
-            success = 0;
+            success = false;
             goto finalize_session;
         }
     }
 
 finalize_session:
-    // Commit session if we streamed everything okay; otherwise abandon
+    // Commit session if we streamed everything okay; otherwise abandon.
     std::string service = android::base::StringPrintf("%s install-%s %d", install_cmd.c_str(),
                                                       success ? "commit" : "abandon", session_id);
     {
@@ -512,14 +513,16 @@
         }
         read_status_line(fd.get(), buf, sizeof(buf));
     }
+    if (!success) return EXIT_FAILURE;
 
-    if (!strncmp("Success", buf, 7)) {
-        fputs(buf, stdout);
-        return 0;
+    if (strncmp("Success", buf, 7)) {
+        fprintf(stderr, "adb: failed to finalize session\n");
+        fputs(buf, stderr);
+        return EXIT_FAILURE;
     }
-    fprintf(stderr, "adb: failed to finalize session\n");
-    fputs(buf, stderr);
-    return EXIT_FAILURE;
+
+    fputs(buf, stdout);
+    return EXIT_SUCCESS;
 }
 
 int install_multi_package(int argc, const char** argv) {
@@ -739,6 +742,20 @@
 }
 
 int delete_device_file(const std::string& filename) {
-    std::string cmd = "rm -f " + escape_arg(filename);
-    return send_shell_command(cmd);
+    // http://b/17339227 "Sideloading a Readonly File Results in a Prompt to
+    // Delete" caused us to add `-f` here, to avoid the equivalent of the `-i`
+    // prompt that you get from BSD rm (used in Android 5) if you have a
+    // non-writable file and stdin is a tty (which is true for old versions of
+    // adbd).
+    //
+    // Unfortunately, `rm -f` requires Android 4.3, so that workaround broke
+    // earlier Android releases. This was reported as http://b/37704384 "adb
+    // install -r passes invalid argument to rm on Android 4.1" and
+    // http://b/37035817 "ADB Fails: rm failed for -f, No such file or
+    // directory".
+    //
+    // Testing on a variety of devices and emulators shows that redirecting
+    // stdin is sufficient to avoid the pseudo-`-i`, and works on toolbox,
+    // BSD, and toybox versions of rm.
+    return send_shell_command("rm " + escape_arg(filename) + " </dev/null");
 }
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index c80d329..7d0eb40 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -153,6 +153,7 @@
         "     -d: allow version code downgrade (debuggable packages only)\n"
         "     -p: partial application install (install-multiple only)\n"
         "     -g: grant all runtime permissions\n"
+        "     --abi ABI: override platform's default ABI\n"
         "     --instant: cause the app to be installed as an ephemeral install app\n"
         "     --no-streaming: always push APK to device and invoke Package Manager as separate steps\n"
         "     --streaming: force streaming APK directly into Package Manager\n"
@@ -164,6 +165,7 @@
 #ifndef _WIN32
         "     --local-agent: locate agent files from local source build (instead of SDK location)\n"
 #endif
+        "     (See also `adb shell pm help` for more options.)\n"
         //TODO--installlog <filename>
         " uninstall [-k] PACKAGE\n"
         "     remove this app package from the device\n"
@@ -1882,7 +1884,10 @@
     } else if (!strcmp(argv[0], "track-jdwp")) {
         return adb_connect_command("track-jdwp");
     } else if (!strcmp(argv[0], "track-devices")) {
-        return adb_connect_command("host:track-devices");
+        if (argc > 2 || (argc == 2 && strcmp(argv[1], "-l"))) {
+            error_exit("usage: adb track-devices [-l]");
+        }
+        return adb_connect_command(argc == 2 ? "host:track-devices-l" : "host:track-devices");
     } else if (!strcmp(argv[0], "raw")) {
         if (argc != 2) {
             error_exit("usage: adb raw SERVICE");
diff --git a/adb/transport.cpp b/adb/transport.cpp
index 8bc925f..3d1d620 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -542,9 +542,7 @@
     // for the first time, even if no update occurred.
     if (tracker->update_needed) {
         tracker->update_needed = false;
-
-        std::string transports = list_transports(tracker->long_output);
-        device_tracker_send(tracker, transports);
+        device_tracker_send(tracker, list_transports(tracker->long_output));
     }
 }
 
@@ -587,13 +585,11 @@
     update_transport_status();
 
     // Notify `adb track-devices` clients.
-    std::string transports = list_transports(false);
-
     device_tracker* tracker = device_tracker_list;
     while (tracker != nullptr) {
         device_tracker* next = tracker->next;
         // This may destroy the tracker if the connection is closed.
-        device_tracker_send(tracker, transports);
+        device_tracker_send(tracker, list_transports(tracker->long_output));
         tracker = next;
     }
 }
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 9a0f4fe..bc197cd 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -46,7 +46,7 @@
 namespace fs_mgr {
 namespace {
 
-const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android");
+constexpr char kDefaultAndroidDtDir[] = "/proc/device-tree/firmware/android";
 
 struct FlagList {
     const char *name;
diff --git a/fs_mgr/libdm/dm_target.cpp b/fs_mgr/libdm/dm_target.cpp
index da1013e..7c9804c 100644
--- a/fs_mgr/libdm/dm_target.cpp
+++ b/fs_mgr/libdm/dm_target.cpp
@@ -16,6 +16,7 @@
 
 #include "libdm/dm_target.h"
 
+#include <inttypes.h>
 #include <stdio.h>
 #include <sys/types.h>
 
@@ -149,6 +150,25 @@
     return base_device_ + " " + cow_device_ + " " + mode + " " + std::to_string(chunk_size_);
 }
 
+// Computes the percentage of complition for snapshot status.
+// @sectors_initial is the number of sectors_allocated stored right before
+// starting the merge.
+double DmTargetSnapshot::MergePercent(const DmTargetSnapshot::Status& status,
+                                      uint64_t sectors_initial) {
+    uint64_t s = status.sectors_allocated;
+    uint64_t t = status.total_sectors;
+    uint64_t m = status.metadata_sectors;
+    uint64_t i = sectors_initial == 0 ? t : sectors_initial;
+
+    if (t <= s || i <= s) {
+        return 0.0;
+    }
+    if (s == 0 || t == 0 || s <= m) {
+        return 100.0;
+    }
+    return 100.0 / (i - m) * (i - s);
+}
+
 bool DmTargetSnapshot::ReportsOverflow(const std::string& target_type) {
     DeviceMapper& dm = DeviceMapper::Instance();
     DmTargetTypeInfo info;
@@ -165,34 +185,40 @@
 }
 
 bool DmTargetSnapshot::ParseStatusText(const std::string& text, Status* status) {
+    // Try to parse the line as it should be
+    int args = sscanf(text.c_str(), "%" PRIu64 "/%" PRIu64 " %" PRIu64, &status->sectors_allocated,
+                      &status->total_sectors, &status->metadata_sectors);
+    if (args == 3) {
+        return true;
+    }
     auto sections = android::base::Split(text, " ");
+    if (sections.size() == 0) {
+        LOG(ERROR) << "could not parse empty status";
+        return false;
+    }
+    // Error codes are: "Invalid", "Overflow" and "Merge failed"
     if (sections.size() == 1) {
-        // This is probably an error code, "Invalid" is possible as is "Overflow"
-        // on 4.4+.
+        if (text == "Invalid" || text == "Overflow") {
+            status->error = text;
+            return true;
+        }
+    } else if (sections.size() == 2 && text == "Merge failed") {
         status->error = text;
         return true;
     }
-    if (sections.size() != 2) {
-        LOG(ERROR) << "snapshot status should have two components";
+    LOG(ERROR) << "could not parse snapshot status: wrong format";
+    return false;
+}
+
+bool DmTargetSnapshot::GetDevicesFromParams(const std::string& params, std::string* base_device,
+                                            std::string* cow_device) {
+    auto pieces = android::base::Split(params, " ");
+    if (pieces.size() < 2) {
+        LOG(ERROR) << "Parameter string is invalid: " << params;
         return false;
     }
-    auto sector_info = android::base::Split(sections[0], "/");
-    if (sector_info.size() != 2) {
-        LOG(ERROR) << "snapshot sector info should have two components";
-        return false;
-    }
-    if (!android::base::ParseUint(sections[1], &status->metadata_sectors)) {
-        LOG(ERROR) << "could not parse metadata sectors";
-        return false;
-    }
-    if (!android::base::ParseUint(sector_info[0], &status->sectors_allocated)) {
-        LOG(ERROR) << "could not parse sectors allocated";
-        return false;
-    }
-    if (!android::base::ParseUint(sector_info[1], &status->total_sectors)) {
-        LOG(ERROR) << "could not parse total sectors";
-        return false;
-    }
+    *base_device = pieces[0];
+    *cow_device = pieces[1];
     return true;
 }
 
diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index da1c4a9..eed21dc 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -456,6 +456,87 @@
     }
 }
 
+TEST(libdm, ParseStatusText) {
+    DmTargetSnapshot::Status status;
+
+    // Bad inputs
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("X", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123/456", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123 456", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123 456", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123 456 789", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123 456/789", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123/456/789", &status));
+    EXPECT_FALSE(DmTargetSnapshot::ParseStatusText("123 / 456 789", &status));
+
+    // Good input
+    EXPECT_TRUE(DmTargetSnapshot::ParseStatusText("123/456 789", &status));
+    EXPECT_EQ(status.sectors_allocated, 123);
+    EXPECT_EQ(status.total_sectors, 456);
+    EXPECT_EQ(status.metadata_sectors, 789);
+
+    // Known error codes
+    EXPECT_TRUE(DmTargetSnapshot::ParseStatusText("Invalid", &status));
+    EXPECT_TRUE(DmTargetSnapshot::ParseStatusText("Merge failed", &status));
+    EXPECT_TRUE(DmTargetSnapshot::ParseStatusText("Overflow", &status));
+}
+
+TEST(libdm, DmSnapshotMergePercent) {
+    DmTargetSnapshot::Status status;
+
+    // Correct input
+    status.sectors_allocated = 1000;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 0;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status), 1.0);
+
+    status.sectors_allocated = 500;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 0;
+    EXPECT_GE(DmTargetSnapshot::MergePercent(status), 49.0);
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status), 51.0);
+
+    status.sectors_allocated = 0;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 0;
+    EXPECT_GE(DmTargetSnapshot::MergePercent(status), 99.0);
+
+    status.sectors_allocated = 500;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 500;
+    EXPECT_GE(DmTargetSnapshot::MergePercent(status), 99.0);
+
+    status.sectors_allocated = 500;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 0;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status, 500), 1.0);
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status, 1000), 51.0);
+    EXPECT_GE(DmTargetSnapshot::MergePercent(status, 1000), 49.0);
+
+    // Robustness
+    status.sectors_allocated = 2000;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 0;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status), 0.0);
+
+    status.sectors_allocated = 2000;
+    status.total_sectors = 1000;
+    status.metadata_sectors = 2000;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status), 0.0);
+
+    status.sectors_allocated = 2000;
+    status.total_sectors = 0;
+    status.metadata_sectors = 2000;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status), 0.0);
+
+    status.sectors_allocated = 1000;
+    status.total_sectors = 0;
+    status.metadata_sectors = 1000;
+    EXPECT_LE(DmTargetSnapshot::MergePercent(status, 0), 0.0);
+}
+
 TEST(libdm, CryptArgs) {
     DmTargetCrypt target1(0, 512, "sha1", "abcdefgh", 50, "/dev/loop0", 100);
     ASSERT_EQ(target1.name(), "crypt");
diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index c6b37cf..f5783cb 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -47,6 +47,8 @@
 
 enum class DmDeviceState { INVALID, SUSPENDED, ACTIVE };
 
+static constexpr uint64_t kSectorSize = 512;
+
 class DeviceMapper final {
   public:
     class DmBlockDevice final {
diff --git a/fs_mgr/libdm/include/libdm/dm_target.h b/fs_mgr/libdm/include/libdm/dm_target.h
index 722922d..a66ab7a 100644
--- a/fs_mgr/libdm/include/libdm/dm_target.h
+++ b/fs_mgr/libdm/include/libdm/dm_target.h
@@ -216,8 +216,11 @@
         std::string error;
     };
 
+    static double MergePercent(const Status& status, uint64_t sectors_initial = 0);
     static bool ParseStatusText(const std::string& text, Status* status);
     static bool ReportsOverflow(const std::string& target_type);
+    static bool GetDevicesFromParams(const std::string& params, std::string* base_device,
+                                     std::string* cow_device);
 
   private:
     std::string base_device_;
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
index b504161..5b377ae 100644
--- a/fs_mgr/liblp/Android.bp
+++ b/fs_mgr/liblp/Android.bp
@@ -36,6 +36,7 @@
         "builder.cpp",
         "images.cpp",
         "partition_opener.cpp",
+        "property_fetcher.cpp",
         "reader.cpp",
         "utility.cpp",
         "writer.cpp",
diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index 8797ea9..777743c 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -20,21 +20,16 @@
 
 #include <algorithm>
 
-#include <android-base/properties.h>
 #include <android-base/unique_fd.h>
 
 #include "liblp/liblp.h"
+#include "liblp/property_fetcher.h"
 #include "reader.h"
 #include "utility.h"
 
 namespace android {
 namespace fs_mgr {
 
-std::optional<bool> MetadataBuilder::sABOverride;
-std::optional<bool> MetadataBuilder::sRetrofitDap;
-
-static const std::string kDefaultGroup = "default";
-
 bool LinearExtent::AddTo(LpMetadata* out) const {
     if (device_index_ >= out->block_devices.size()) {
         LERROR << "Extent references unknown block device.";
@@ -164,16 +159,27 @@
         return nullptr;
     }
 
-    // On non-retrofit devices there is only one location for metadata: the
-    // super partition. update_engine will remove and resize partitions as
-    // needed. On the other hand, for retrofit devices, we'll need to
-    // translate block device and group names to update their slot suffixes.
+    // On retrofit DAP devices, modify the metadata so that it is suitable for being written
+    // to the target slot later. We detect retrofit DAP devices by checking the super partition
+    // name and system properties.
+    // See comments for UpdateMetadataForOtherSuper.
     auto super_device = GetMetadataSuperBlockDevice(*metadata.get());
-    if (GetBlockDevicePartitionName(*super_device) == "super" ||
-        !IsRetrofitDynamicPartitionsDevice()) {
-        return New(*metadata.get(), &opener);
+    if (GetBlockDevicePartitionName(*super_device) != "super" &&
+        IsRetrofitDynamicPartitionsDevice()) {
+        if (!UpdateMetadataForOtherSuper(metadata.get(), source_slot_number, target_slot_number)) {
+            return nullptr;
+        }
     }
 
+    return New(*metadata.get(), &opener);
+}
+
+// For retrofit DAP devices, there are (conceptually) two super partitions. We'll need to translate
+// block device and group names to update their slot suffixes.
+// (On the other hand, On non-retrofit DAP devices there is only one location for metadata: the
+// super partition. update_engine will remove and resize partitions as needed.)
+bool MetadataBuilder::UpdateMetadataForOtherSuper(LpMetadata* metadata, uint32_t source_slot_number,
+                                                  uint32_t target_slot_number) {
     // Clear partitions and extents, since they have no meaning on the target
     // slot. We also clear groups since they are re-added during OTA.
     metadata->partitions.clear();
@@ -193,7 +199,7 @@
             // refers to a target or unknown block device.
             LERROR << "Invalid block device for slot " << source_slot_suffix << ": "
                    << partition_name;
-            return nullptr;
+            return false;
         }
         std::string new_name =
                 partition_name.substr(0, partition_name.size() - slot_suffix.size()) +
@@ -202,20 +208,12 @@
         auto new_device = source_block_device;
         if (!UpdateBlockDevicePartitionName(&new_device, new_name)) {
             LERROR << "Partition name too long: " << new_name;
-            return nullptr;
+            return false;
         }
         metadata->block_devices.emplace_back(new_device);
     }
 
-    return New(*metadata.get(), &opener);
-}
-
-void MetadataBuilder::OverrideABForTesting(bool ab_device) {
-    sABOverride = ab_device;
-}
-
-void MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(bool retrofit) {
-    sRetrofitDap = retrofit;
+    return true;
 }
 
 MetadataBuilder::MetadataBuilder() : auto_slot_suffixing_(false) {
@@ -414,7 +412,7 @@
     geometry_.metadata_slot_count = metadata_slot_count;
     geometry_.logical_block_size = logical_block_size;
 
-    if (!AddGroup(kDefaultGroup, 0)) {
+    if (!AddGroup(std::string(kDefaultGroup), 0)) {
         return false;
     }
     return true;
@@ -430,7 +428,7 @@
 }
 
 Partition* MetadataBuilder::AddPartition(const std::string& name, uint32_t attributes) {
-    return AddPartition(name, kDefaultGroup, attributes);
+    return AddPartition(name, std::string(kDefaultGroup), attributes);
 }
 
 Partition* MetadataBuilder::AddPartition(const std::string& name, const std::string& group_name,
@@ -1050,17 +1048,12 @@
 }
 
 bool MetadataBuilder::IsABDevice() {
-    if (sABOverride.has_value()) {
-        return *sABOverride;
-    }
-    return !android::base::GetProperty("ro.boot.slot_suffix", "").empty();
+    return !IPropertyFetcher::GetInstance()->GetProperty("ro.boot.slot_suffix", "").empty();
 }
 
 bool MetadataBuilder::IsRetrofitDynamicPartitionsDevice() {
-    if (sRetrofitDap.has_value()) {
-        return *sRetrofitDap;
-    }
-    return android::base::GetBoolProperty("ro.boot.dynamic_partitions_retrofit", false);
+    return IPropertyFetcher::GetInstance()->GetBoolProperty("ro.boot.dynamic_partitions_retrofit",
+                                                            false);
 }
 
 bool MetadataBuilder::IsRetrofitMetadata() const {
diff --git a/fs_mgr/liblp/builder_test.cpp b/fs_mgr/liblp/builder_test.cpp
index 377ec68..6d27873 100644
--- a/fs_mgr/liblp/builder_test.cpp
+++ b/fs_mgr/liblp/builder_test.cpp
@@ -19,36 +19,40 @@
 #include <gtest/gtest.h>
 #include <liblp/builder.h>
 
+#include "mock_property_fetcher.h"
 #include "utility.h"
 
 using namespace std;
 using namespace android::fs_mgr;
+using ::android::fs_mgr::MockPropertyFetcher;
+using ::testing::_;
+using ::testing::AnyNumber;
 using ::testing::ElementsAre;
+using ::testing::NiceMock;
+using ::testing::Return;
+
+static void ResetPropertyFetcher() {
+    IPropertyFetcher::OverrideForTesting(std::make_unique<NiceMock<MockPropertyFetcher>>());
+}
+
+MockPropertyFetcher* GetMockedInstance() {
+    return static_cast<MockPropertyFetcher*>(IPropertyFetcher::GetInstance());
+}
 
 class Environment : public ::testing::Environment {
   public:
-    void SetUp() override {
-        MetadataBuilder::OverrideABForTesting(false);
-        MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(false);
-    }
+    void SetUp() override { ResetPropertyFetcher(); }
 };
 
 int main(int argc, char** argv) {
-    ::testing::AddGlobalTestEnvironment(new Environment);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
 }
 
 class BuilderTest : public ::testing::Test {
   public:
-    void SetUp() override {
-        MetadataBuilder::OverrideABForTesting(false);
-        MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(false);
-    }
-    void TearDown() override {
-        MetadataBuilder::OverrideABForTesting(false);
-        MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(false);
-    }
+    void SetUp() override { ResetPropertyFetcher(); }
+    void TearDown() override { ResetPropertyFetcher(); }
 };
 
 TEST_F(BuilderTest, BuildBasic) {
@@ -785,7 +789,9 @@
 
     // A and B slots should be allocated from separate halves of the partition,
     // to mitigate allocating too many extents. (b/120433288)
-    MetadataBuilder::OverrideABForTesting(true);
+    ON_CALL(*GetMockedInstance(), GetProperty("ro.boot.slot_suffix", _))
+            .WillByDefault(Return("_a"));
+
     auto builder = MetadataBuilder::New(device_info, 65536, 2);
     ASSERT_NE(builder, nullptr);
     Partition* system_a = builder->AddPartition("system_a", 0);
diff --git a/fs_mgr/liblp/include/liblp/builder.h b/fs_mgr/liblp/include/liblp/builder.h
index a2221ef..3b229bd 100644
--- a/fs_mgr/liblp/include/liblp/builder.h
+++ b/fs_mgr/liblp/include/liblp/builder.h
@@ -24,6 +24,7 @@
 #include <memory>
 #include <optional>
 #include <set>
+#include <string_view>
 
 #include "liblp.h"
 #include "partition_opener.h"
@@ -37,6 +38,9 @@
 static const uint32_t kDefaultPartitionAlignment = 1024 * 1024;
 static const uint32_t kDefaultBlockSize = 4096;
 
+// Name of the default group in a metadata.
+static constexpr std::string_view kDefaultGroup = "default";
+
 // Abstraction around dm-targets that can be encoded into logical partition tables.
 class Extent {
   public:
@@ -196,12 +200,6 @@
         return New(device_info, metadata_max_size, metadata_slot_count);
     }
 
-    // Used by the test harness to override whether the device is "A/B".
-    static void OverrideABForTesting(bool ab_device);
-
-    // Used by the test harness to override whether the device is "retrofitting dynamic partitions".
-    static void OverrideRetrofitDynamicParititonsForTesting(bool retrofit);
-
     // Define a new partition group. By default there is one group called
     // "default", with an unrestricted size. A non-zero size will restrict the
     // total space used by all partitions in the group.
@@ -347,8 +345,8 @@
                                                     const std::vector<Interval>& free_list,
                                                     uint64_t sectors_needed) const;
 
-    static std::optional<bool> sABOverride;
-    static std::optional<bool> sRetrofitDap;
+    static bool UpdateMetadataForOtherSuper(LpMetadata* metadata, uint32_t source_slot_number,
+                                            uint32_t target_slot_number);
 
     LpMetadataGeometry geometry_;
     LpMetadataHeader header_;
diff --git a/fs_mgr/liblp/include/liblp/property_fetcher.h b/fs_mgr/liblp/include/liblp/property_fetcher.h
new file mode 100644
index 0000000..e73a1f5
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/property_fetcher.h
@@ -0,0 +1,42 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#pragma once
+
+#include <memory>
+
+namespace android {
+namespace fs_mgr {
+
+class IPropertyFetcher {
+  public:
+    virtual ~IPropertyFetcher() = default;
+    virtual std::string GetProperty(const std::string& key, const std::string& defaultValue) = 0;
+    virtual bool GetBoolProperty(const std::string& key, bool defaultValue) = 0;
+
+    static IPropertyFetcher* GetInstance();
+    static void OverrideForTesting(std::unique_ptr<IPropertyFetcher>&&);
+};
+
+class PropertyFetcher : public IPropertyFetcher {
+  public:
+    ~PropertyFetcher() = default;
+    std::string GetProperty(const std::string& key, const std::string& defaultValue) override;
+    bool GetBoolProperty(const std::string& key, bool defaultValue) override;
+};
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/io_test.cpp b/fs_mgr/liblp/io_test.cpp
index 70dd85f..2990863 100644
--- a/fs_mgr/liblp/io_test.cpp
+++ b/fs_mgr/liblp/io_test.cpp
@@ -23,10 +23,12 @@
 #include <android-base/unique_fd.h>
 #include <fs_mgr.h>
 #include <fstab/fstab.h>
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include <liblp/builder.h>
 
 #include "images.h"
+#include "mock_property_fetcher.h"
 #include "reader.h"
 #include "test_partition_opener.h"
 #include "utility.h"
@@ -34,6 +36,8 @@
 
 using namespace std;
 using namespace android::fs_mgr;
+using ::testing::_;
+using ::testing::Return;
 using unique_fd = android::base::unique_fd;
 
 // Our tests assume a 128KiB disk with two 512 byte metadata slots.
@@ -664,7 +668,8 @@
 }
 
 TEST(liblp, UpdateRetrofit) {
-    MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(true);
+    ON_CALL(*GetMockedInstance(), GetBoolProperty("ro.boot.dynamic_partitions_retrofit", _))
+            .WillByDefault(Return(true));
 
     unique_ptr<MetadataBuilder> builder = CreateDefaultBuilder();
     ASSERT_NE(builder, nullptr);
@@ -695,7 +700,8 @@
 }
 
 TEST(liblp, UpdateNonRetrofit) {
-    MetadataBuilder::OverrideRetrofitDynamicParititonsForTesting(false);
+    ON_CALL(*GetMockedInstance(), GetBoolProperty("ro.boot.dynamic_partitions_retrofit", _))
+            .WillByDefault(Return(false));
 
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
diff --git a/fs_mgr/liblp/mock_property_fetcher.h b/fs_mgr/liblp/mock_property_fetcher.h
new file mode 100644
index 0000000..eb91de2
--- /dev/null
+++ b/fs_mgr/liblp/mock_property_fetcher.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <gmock/gmock.h>
+
+#include <liblp/property_fetcher.h>
+
+namespace android {
+namespace fs_mgr {
+
+class MockPropertyFetcher : public IPropertyFetcher {
+  public:
+    MOCK_METHOD2(GetProperty, std::string(const std::string&, const std::string&));
+    MOCK_METHOD2(GetBoolProperty, bool(const std::string&, bool));
+
+    // By default, return default_value for all functions.
+    MockPropertyFetcher() {
+        using ::testing::_;
+        using ::testing::Invoke;
+        ON_CALL(*this, GetProperty(_, _)).WillByDefault(Invoke([](const auto&, const auto& def) {
+            return def;
+        }));
+        ON_CALL(*this, GetBoolProperty(_, _)).WillByDefault(Invoke([](const auto&, auto def) {
+            return def;
+        }));
+    }
+};
+
+}  // namespace fs_mgr
+}  // namespace android
+
+android::fs_mgr::MockPropertyFetcher* GetMockedInstance();
diff --git a/fs_mgr/liblp/property_fetcher.cpp b/fs_mgr/liblp/property_fetcher.cpp
new file mode 100644
index 0000000..038ef4d
--- /dev/null
+++ b/fs_mgr/liblp/property_fetcher.cpp
@@ -0,0 +1,49 @@
+/*
+ * 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 "liblp/property_fetcher.h"
+
+#include <memory>
+
+#include <android-base/properties.h>
+
+namespace android {
+namespace fs_mgr {
+
+std::string PropertyFetcher::GetProperty(const std::string& key, const std::string& default_value) {
+    return android::base::GetProperty(key, default_value);
+}
+
+bool PropertyFetcher::GetBoolProperty(const std::string& key, bool default_value) {
+    return android::base::GetBoolProperty(key, default_value);
+}
+
+static std::unique_ptr<IPropertyFetcher>* GetInstanceAllocation() {
+    static std::unique_ptr<IPropertyFetcher> instance = std::make_unique<PropertyFetcher>();
+    return &instance;
+}
+
+IPropertyFetcher* IPropertyFetcher::GetInstance() {
+    return GetInstanceAllocation()->get();
+}
+
+void IPropertyFetcher::OverrideForTesting(std::unique_ptr<IPropertyFetcher>&& fetcher) {
+    GetInstanceAllocation()->swap(fetcher);
+    fetcher.reset();
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 3a08049..52aad12 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -14,15 +14,13 @@
 // limitations under the License.
 //
 
-cc_library {
-    name: "libsnapshot",
-    recovery_available: true,
+cc_defaults {
+    name: "libsnapshot_defaults",
     defaults: ["fs_mgr_defaults"],
-    cppflags: [
+    cflags: [
         "-D_FILE_OFFSET_BITS=64",
-    ],
-    srcs: [
-        "snapshot.cpp",
+        "-Wall",
+        "-Werror",
     ],
     shared_libs: [
         "libbase",
@@ -30,7 +28,53 @@
     ],
     static_libs: [
         "libdm",
+    ],
+    whole_static_libs: [
         "libext2_uuid",
+        "libext4_utils",
+        "libfiemap",
     ],
     export_include_dirs: ["include"],
 }
+
+filegroup {
+    name: "libsnapshot_sources",
+    srcs: [
+        "snapshot.cpp",
+    ],
+}
+
+cc_library_static {
+    name: "libsnapshot",
+    defaults: ["libsnapshot_defaults"],
+    srcs: [":libsnapshot_sources"],
+    static_libs: [
+        "libfiemap_binder",
+    ],
+}
+
+cc_library_static {
+    name: "libsnapshot_nobinder",
+    defaults: ["libsnapshot_defaults"],
+    srcs: [":libsnapshot_sources"],
+    recovery_available: true,
+}
+
+cc_test {
+    name: "libsnapshot_test",
+    defaults: ["libsnapshot_defaults"],
+    srcs: [
+        "snapshot_test.cpp",
+    ],
+    shared_libs: [
+        "libbinder",
+        "libutils",
+    ],
+    static_libs: [
+        "libcutils",
+        "libcrypto",
+        "libfs_mgr",
+        "liblp",
+        "libsnapshot",
+    ],
+}
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 5cfd7fa..062e00b 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -19,14 +19,32 @@
 #include <chrono>
 #include <memory>
 #include <string>
+#include <vector>
+
+#include <android-base/unique_fd.h>
+#include <libdm/dm_target.h>
+
+#ifndef FRIEND_TEST
+#define FRIEND_TEST(test_set_name, individual_test) \
+    friend class test_set_name##_##individual_test##_Test
+#define DEFINED_FRIEND_TEST
+#endif
 
 namespace android {
+
+namespace fiemap {
+class IImageManager;
+}  // namespace fiemap
+
 namespace snapshot {
 
-enum class UpdateStatus {
+enum class UpdateState {
     // No update or merge is in progress.
     None,
 
+    // An update is applying; snapshots may already exist.
+    Initiated,
+
     // An update is pending, but has not been successfully booted yet.
     Unverified,
 
@@ -34,36 +52,41 @@
     Merging,
 
     // Merging is complete, and needs to be acknowledged.
-    MergeCompleted
+    MergeCompleted,
+
+    // Merging failed due to an unrecoverable error.
+    MergeFailed
 };
 
 class SnapshotManager final {
   public:
-    // Return a new SnapshotManager instance, or null on error.
-    static std::unique_ptr<SnapshotManager> New();
+    // Dependency injection for testing.
+    class IDeviceInfo {
+      public:
+        virtual ~IDeviceInfo() {}
+        virtual std::string GetGsidDir() const = 0;
+        virtual std::string GetMetadataDir() const = 0;
 
-    // Create a new snapshot device with the given name, base device, and COW device
-    // size. The new device path will be returned in |dev_path|. If timeout_ms is
-    // greater than zero, this function will wait the given amount of time for
-    // |dev_path| to become available, and fail otherwise. If timeout_ms is 0, then
-    // no wait will occur and |dev_path| may not yet exist on return.
-    bool CreateSnapshot(const std::string& name, const std::string& base_device, uint64_t cow_size,
-                        std::string* dev_path, const std::chrono::milliseconds& timeout_ms);
+        // Return true if the device is currently running off snapshot devices,
+        // indicating that we have booted after applying (but not merging) an
+        // OTA.
+        virtual bool IsRunningSnapshot() const = 0;
+    };
 
-    // Map a snapshot device that was previously created with CreateSnapshot.
-    // If a merge was previously initiated, the device-mapper table will have a
-    // snapshot-merge target instead of a snapshot target. The timeout parameter
-    // is the same as in CreateSnapshotDevice.
-    bool MapSnapshotDevice(const std::string& name, const std::string& base_device,
-                           const std::chrono::milliseconds& timeout_ms, std::string* dev_path);
+    ~SnapshotManager();
 
-    // Unmap a snapshot device previously mapped with MapSnapshotDevice().
-    bool UnmapSnapshotDevice(const std::string& name);
+    // Return a new SnapshotManager instance, or null on error. The device
+    // pointer is owned for the lifetime of SnapshotManager. If null, a default
+    // instance will be created.
+    static std::unique_ptr<SnapshotManager> New(IDeviceInfo* device = nullptr);
 
-    // Remove the backing copy-on-write image for the named snapshot. If the
-    // device is still mapped, this will attempt an Unmap, and fail if the
-    // unmap fails.
-    bool DeleteSnapshot(const std::string& name);
+    // Begin an update. This must be called before creating any snapshots. It
+    // will fail if GetUpdateState() != None.
+    bool BeginUpdate();
+
+    // Cancel an update; any snapshots will be deleted. This will fail if the
+    // state != Initiated or None.
+    bool CancelUpdate();
 
     // Initiate a merge on all snapshot devices. This should only be used after an
     // update has been marked successful after booting.
@@ -77,12 +100,128 @@
     // Find the status of the current update, if any.
     //
     // |progress| depends on the returned status:
-    //   None: 0
-    //   Unverified: 0
-    //   Merging: Value in the range [0, 100)
+    //   Merging: Value in the range [0, 100]
     //   MergeCompleted: 100
-    UpdateStatus GetUpdateStatus(double* progress);
+    //   Other: 0
+    UpdateState GetUpdateState(double* progress = nullptr);
+
+  private:
+    FRIEND_TEST(SnapshotTest, CreateSnapshot);
+    FRIEND_TEST(SnapshotTest, MapSnapshot);
+    FRIEND_TEST(SnapshotTest, MapPartialSnapshot);
+    friend class SnapshotTest;
+
+    using IImageManager = android::fiemap::IImageManager;
+
+    explicit SnapshotManager(IDeviceInfo* info);
+
+    // This is created lazily since it connects via binder.
+    bool EnsureImageManager();
+
+    // Helper function for tests.
+    IImageManager* image_manager() const { return images_.get(); }
+
+    // Since libsnapshot is included into multiple processes, we flock() our
+    // files for simple synchronization. LockedFile is a helper to assist with
+    // this. It also serves as a proof-of-lock for some functions.
+    class LockedFile final {
+      public:
+        LockedFile(const std::string& path, android::base::unique_fd&& fd)
+            : path_(path), fd_(std::move(fd)) {}
+        ~LockedFile();
+
+        const std::string& path() const { return path_; }
+        int fd() const { return fd_; }
+
+      private:
+        std::string path_;
+        android::base::unique_fd fd_;
+    };
+    std::unique_ptr<LockedFile> OpenFile(const std::string& file, int open_flags, int lock_flags);
+    bool Truncate(LockedFile* file);
+
+    // Create a new snapshot record. This creates the backing COW store and
+    // persists information needed to map the device. The device can be mapped
+    // with MapSnapshot().
+    //
+    // |device_size| should be the size of the base_device that will be passed
+    // via MapDevice(). |snapshot_size| should be the number of bytes in the
+    // base device, starting from 0, that will be snapshotted. The cow_size
+    // should be the amount of space that will be allocated to store snapshot
+    // deltas.
+    //
+    // If |snapshot_size| < device_size, then the device will always
+    // be mapped with two table entries: a dm-snapshot range covering
+    // snapshot_size, and a dm-linear range covering the remainder.
+    //
+    // All sizes are specified in bytes, and the device and snapshot sizes
+    // must be a multiple of the sector size (512 bytes). |cow_size| will
+    // be rounded up to the nearest sector.
+    bool CreateSnapshot(LockedFile* lock, const std::string& name, uint64_t device_size,
+                        uint64_t snapshot_size, uint64_t cow_size);
+
+    // Map a snapshot device that was previously created with CreateSnapshot.
+    // If a merge was previously initiated, the device-mapper table will have a
+    // snapshot-merge target instead of a snapshot target. If the timeout
+    // parameter greater than zero, this function will wait the given amount
+    // of time for |dev_path| to become available, and fail otherwise. If
+    // timeout_ms is 0, then no wait will occur and |dev_path| may not yet
+    // exist on return.
+    bool MapSnapshot(LockedFile* lock, const std::string& name, const std::string& base_device,
+                     const std::chrono::milliseconds& timeout_ms, std::string* dev_path);
+
+    // Remove the backing copy-on-write image for the named snapshot. The
+    // caller is responsible for ensuring that the snapshot is unmapped.
+    bool DeleteSnapshot(LockedFile* lock, const std::string& name);
+
+    // Unmap a snapshot device previously mapped with MapSnapshotDevice().
+    bool UnmapSnapshot(LockedFile* lock, const std::string& name);
+
+    // Unmap and remove all known snapshots.
+    bool RemoveAllSnapshots(LockedFile* lock);
+
+    // List the known snapshot names.
+    bool ListSnapshots(LockedFile* lock, std::vector<std::string>* snapshots);
+
+    // Interact with /metadata/ota/state.
+    std::unique_ptr<LockedFile> OpenStateFile(int open_flags, int lock_flags);
+    std::unique_ptr<LockedFile> LockShared();
+    std::unique_ptr<LockedFile> LockExclusive();
+    UpdateState ReadUpdateState(LockedFile* file);
+    bool WriteUpdateState(LockedFile* file, UpdateState state);
+
+    // This state is persisted per-snapshot in /metadata/ota/snapshots/.
+    struct SnapshotStatus {
+        std::string state;
+        uint64_t device_size;
+        uint64_t snapshot_size;
+        // These are non-zero when merging.
+        uint64_t sectors_allocated = 0;
+        uint64_t metadata_sectors = 0;
+    };
+
+    // Interact with status files under /metadata/ota/snapshots.
+    std::unique_ptr<LockedFile> OpenSnapshotStatusFile(const std::string& name, int open_flags,
+                                                       int lock_flags);
+    bool WriteSnapshotStatus(LockedFile* file, const SnapshotStatus& status);
+    bool ReadSnapshotStatus(LockedFile* file, SnapshotStatus* status);
+
+    // Return the name of the device holding the "snapshot" or "snapshot-merge"
+    // target. This may not be the final device presented via MapSnapshot(), if
+    // for example there is a linear segment.
+    std::string GetSnapshotDeviceName(const std::string& snapshot_name,
+                                      const SnapshotStatus& status);
+
+    std::string gsid_dir_;
+    std::string metadata_dir_;
+    std::unique_ptr<IDeviceInfo> device_;
+    std::unique_ptr<IImageManager> images_;
 };
 
 }  // namespace snapshot
 }  // namespace android
+
+#ifdef DEFINED_FRIEND_TEST
+#undef DEFINED_FRIEND_TEST
+#undef FRIEND_TEST
+#endif
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 3e80239..ef56179 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -14,45 +14,309 @@
 
 #include <libsnapshot/snapshot.h>
 
+#include <dirent.h>
+#include <sys/file.h>
+#include <sys/types.h>
+#include <sys/unistd.h>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/strings.h>
+#include <android-base/unique_fd.h>
+#include <ext4_utils/ext4_utils.h>
+#include <libdm/dm.h>
+#include <libfiemap/image_manager.h>
+
 namespace android {
 namespace snapshot {
 
-std::unique_ptr<SnapshotManager> SnapshotManager::New() {
-    return std::make_unique<SnapshotManager>();
+using android::base::unique_fd;
+using android::dm::DeviceMapper;
+using android::dm::DmDeviceState;
+using android::dm::DmTable;
+using android::dm::DmTargetLinear;
+using android::dm::DmTargetSnapshot;
+using android::dm::kSectorSize;
+using android::dm::SnapshotStorageMode;
+using android::fiemap::IImageManager;
+using namespace std::chrono_literals;
+using namespace std::string_literals;
+
+// Unit is sectors, this is a 4K chunk.
+static constexpr uint32_t kSnapshotChunkSize = 8;
+
+class DeviceInfo final : public SnapshotManager::IDeviceInfo {
+  public:
+    std::string GetGsidDir() const override { return "ota"s; }
+    std::string GetMetadataDir() const override { return "/metadata/ota"s; }
+    bool IsRunningSnapshot() const override;
+};
+
+bool DeviceInfo::IsRunningSnapshot() const {
+    // :TODO: implement this check.
+    return true;
 }
 
-bool SnapshotManager::CreateSnapshot(const std::string& name, const std::string& base_device,
-                                     uint64_t cow_size, std::string* dev_path,
-                                     const std::chrono::milliseconds& timeout_ms) {
-    // (1) Create COW device using libgsi_image.
-    // (2) Create snapshot device using libdm + DmTargetSnapshot.
-    // (3) Record partition in /metadata/ota.
-    (void)name;
-    (void)base_device;
-    (void)cow_size;
-    (void)dev_path;
-    (void)timeout_ms;
-    return false;
+// Note: IIMageManager is an incomplete type in the header, so the default
+// destructor doesn't work.
+SnapshotManager::~SnapshotManager() {}
+
+std::unique_ptr<SnapshotManager> SnapshotManager::New(IDeviceInfo* info) {
+    if (!info) {
+        info = new DeviceInfo();
+    }
+    return std::unique_ptr<SnapshotManager>(new SnapshotManager(info));
 }
 
-bool SnapshotManager::MapSnapshotDevice(const std::string& name, const std::string& base_device,
-                                        const std::chrono::milliseconds& timeout_ms,
-                                        std::string* dev_path) {
-    (void)name;
-    (void)base_device;
-    (void)dev_path;
-    (void)timeout_ms;
-    return false;
+SnapshotManager::SnapshotManager(IDeviceInfo* device) : device_(device) {
+    gsid_dir_ = device_->GetGsidDir();
+    metadata_dir_ = device_->GetMetadataDir();
 }
 
-bool SnapshotManager::UnmapSnapshotDevice(const std::string& name) {
-    (void)name;
-    return false;
+static std::string GetCowName(const std::string& snapshot_name) {
+    return snapshot_name + "-cow";
 }
 
-bool SnapshotManager::DeleteSnapshot(const std::string& name) {
-    (void)name;
-    return false;
+bool SnapshotManager::BeginUpdate() {
+    auto file = LockExclusive();
+    if (!file) return false;
+
+    auto state = ReadUpdateState(file.get());
+    if (state != UpdateState::None) {
+        LOG(ERROR) << "An update is already in progress, cannot begin a new update";
+        return false;
+    }
+    return WriteUpdateState(file.get(), UpdateState::Initiated);
+}
+
+bool SnapshotManager::CancelUpdate() {
+    auto file = LockExclusive();
+    if (!file) return false;
+
+    UpdateState state = ReadUpdateState(file.get());
+    if (state == UpdateState::None) return true;
+    if (state != UpdateState::Initiated) {
+        LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
+        return false;
+    }
+
+    if (!RemoveAllSnapshots(file.get())) {
+        LOG(ERROR) << "Could not remove all snapshots";
+        return false;
+    }
+
+    if (!WriteUpdateState(file.get(), UpdateState::None)) {
+        LOG(ERROR) << "Could not write new update state";
+        return false;
+    }
+    return true;
+}
+
+bool SnapshotManager::CreateSnapshot(LockedFile* lock, const std::string& name,
+                                     uint64_t device_size, uint64_t snapshot_size,
+                                     uint64_t cow_size) {
+    CHECK(lock);
+    if (!EnsureImageManager()) return false;
+
+    // Sanity check these sizes. Like liblp, we guarantee the partition size
+    // is respected, which means it has to be sector-aligned. (This guarantee
+    // is useful for locating avb footers correctly). The COW size, however,
+    // can be arbitrarily larger than specified, so we can safely round it up.
+    if (device_size % kSectorSize != 0) {
+        LOG(ERROR) << "Snapshot " << name
+                   << " device size is not a multiple of the sector size: " << device_size;
+        return false;
+    }
+    if (snapshot_size % kSectorSize != 0) {
+        LOG(ERROR) << "Snapshot " << name
+                   << " snapshot size is not a multiple of the sector size: " << snapshot_size;
+        return false;
+    }
+
+    // Round the COW size up to the nearest sector.
+    cow_size += kSectorSize - 1;
+    cow_size &= ~(kSectorSize - 1);
+
+    LOG(INFO) << "Snapshot " << name << " will have COW size " << cow_size;
+
+    auto status_file = OpenSnapshotStatusFile(name, O_RDWR | O_CREAT, LOCK_EX);
+    if (!status_file) return false;
+
+    // Note, we leave the status file hanging around if we fail to create the
+    // actual backing image. This is harmless, since it'll get removed when
+    // CancelUpdate is called.
+    SnapshotStatus status = {
+            .state = "created",
+            .device_size = device_size,
+            .snapshot_size = snapshot_size,
+    };
+    if (!WriteSnapshotStatus(status_file.get(), status)) {
+        PLOG(ERROR) << "Could not write snapshot status: " << name;
+        return false;
+    }
+
+    auto cow_name = GetCowName(name);
+    int cow_flags = IImageManager::CREATE_IMAGE_ZERO_FILL;
+    return images_->CreateBackingImage(cow_name, cow_size, cow_flags);
+}
+
+bool SnapshotManager::MapSnapshot(LockedFile* lock, const std::string& name,
+                                  const std::string& base_device,
+                                  const std::chrono::milliseconds& timeout_ms,
+                                  std::string* dev_path) {
+    CHECK(lock);
+    if (!EnsureImageManager()) return false;
+
+    auto status_file = OpenSnapshotStatusFile(name, O_RDWR, LOCK_EX);
+    if (!status_file) return false;
+
+    SnapshotStatus status;
+    if (!ReadSnapshotStatus(status_file.get(), &status)) {
+        return false;
+    }
+
+    // Validate the block device size, as well as the requested snapshot size.
+    // During this we also compute the linear sector region if any.
+    {
+        unique_fd fd(open(base_device.c_str(), O_RDONLY | O_CLOEXEC));
+        if (fd < 0) {
+            PLOG(ERROR) << "open failed: " << base_device;
+            return false;
+        }
+        auto dev_size = get_block_device_size(fd);
+        if (!dev_size) {
+            PLOG(ERROR) << "Could not determine block device size: " << base_device;
+            return false;
+        }
+        if (status.device_size != dev_size) {
+            LOG(ERROR) << "Block device size for " << base_device << " does not match"
+                       << "(expected " << status.device_size << ", got " << dev_size << ")";
+            return false;
+        }
+    }
+    if (status.device_size % kSectorSize != 0) {
+        LOG(ERROR) << "invalid blockdev size for " << base_device << ": " << status.device_size;
+        return false;
+    }
+    if (status.snapshot_size % kSectorSize != 0 || status.snapshot_size > status.device_size) {
+        LOG(ERROR) << "Invalid snapshot size for " << base_device << ": " << status.snapshot_size;
+        return false;
+    }
+    uint64_t snapshot_sectors = status.snapshot_size / kSectorSize;
+    uint64_t linear_sectors = (status.device_size - status.snapshot_size) / kSectorSize;
+
+    auto cow_name = GetCowName(name);
+
+    std::string cow_dev;
+    if (!images_->MapImageDevice(cow_name, timeout_ms, &cow_dev)) {
+        return false;
+    }
+
+    auto& dm = DeviceMapper::Instance();
+
+    // Merging is a global state, not per-snapshot. We do however track the
+    // progress of individual snapshots' merges.
+    SnapshotStorageMode mode;
+    UpdateState update_state = ReadUpdateState(lock);
+    if (update_state == UpdateState::Merging || update_state == UpdateState::MergeCompleted) {
+        mode = SnapshotStorageMode::Merge;
+    } else {
+        mode = SnapshotStorageMode::Persistent;
+    }
+
+    // The kernel (tested on 4.19) crashes horribly if a device has both a snapshot
+    // and a linear target in the same table. Instead, we stack them, and give the
+    // snapshot device a different name. It is not exposed to the caller in this
+    // case.
+    auto snap_name = (linear_sectors > 0) ? name + "-inner" : name;
+
+    DmTable table;
+    table.Emplace<DmTargetSnapshot>(0, snapshot_sectors, base_device, cow_dev, mode,
+                                    kSnapshotChunkSize);
+    if (!dm.CreateDevice(snap_name, table, dev_path, timeout_ms)) {
+        LOG(ERROR) << "Could not create snapshot device: " << snap_name;
+        images_->UnmapImageDevice(cow_name);
+        return false;
+    }
+
+    if (linear_sectors) {
+        // Our stacking will looks like this:
+        //     [linear, linear] ; to snapshot, and non-snapshot region of base device
+        //     [snapshot-inner]
+        //     [base device]   [cow]
+        DmTable table;
+        table.Emplace<DmTargetLinear>(0, snapshot_sectors, *dev_path, 0);
+        table.Emplace<DmTargetLinear>(snapshot_sectors, linear_sectors, base_device,
+                                      snapshot_sectors);
+        if (!dm.CreateDevice(name, table, dev_path, timeout_ms)) {
+            LOG(ERROR) << "Could not create outer snapshot device: " << name;
+            dm.DeleteDevice(snap_name);
+            images_->UnmapImageDevice(cow_name);
+            return false;
+        }
+    }
+
+    // :TODO: when merging is implemented, we need to add an argument to the
+    // status indicating how much progress is left to merge. (device-mapper
+    // does not retain the initial values, so we can't derive them.)
+    return true;
+}
+
+bool SnapshotManager::UnmapSnapshot(LockedFile* lock, const std::string& name) {
+    CHECK(lock);
+    if (!EnsureImageManager()) return false;
+
+    auto status_file = OpenSnapshotStatusFile(name, O_RDWR, LOCK_EX);
+    if (!status_file) return false;
+
+    SnapshotStatus status;
+    if (!ReadSnapshotStatus(status_file.get(), &status)) {
+        return false;
+    }
+
+    auto& dm = DeviceMapper::Instance();
+    if (dm.GetState(name) != DmDeviceState::INVALID && !dm.DeleteDevice(name)) {
+        LOG(ERROR) << "Could not delete snapshot device: " << name;
+        return false;
+    }
+
+    // There may be an extra device, since the kernel doesn't let us have a
+    // snapshot and linear target in the same table.
+    auto dm_name = GetSnapshotDeviceName(name, status);
+    if (name != dm_name && !dm.DeleteDevice(dm_name)) {
+        LOG(ERROR) << "Could not delete inner snapshot device: " << dm_name;
+        return false;
+    }
+
+    auto cow_name = GetCowName(name);
+    if (images_->IsImageMapped(cow_name) && !images_->UnmapImageDevice(cow_name)) {
+        return false;
+    }
+    return true;
+}
+
+bool SnapshotManager::DeleteSnapshot(LockedFile* lock, const std::string& name) {
+    CHECK(lock);
+    if (!EnsureImageManager()) return false;
+
+    // Take the snapshot's lock after Unmap, since it will also try to lock.
+    auto status_file = OpenSnapshotStatusFile(name, O_RDONLY, LOCK_EX);
+    if (!status_file) return false;
+
+    auto cow_name = GetCowName(name);
+    if (!images_->BackingImageExists(cow_name)) {
+        return true;
+    }
+    if (!images_->DeleteBackingImage(cow_name)) {
+        return false;
+    }
+
+    if (!android::base::RemoveFileIfExists(status_file->path())) {
+        LOG(ERROR) << "Failed to remove status file: " << status_file->path();
+        return false;
+    }
+    return true;
 }
 
 bool SnapshotManager::InitiateMerge() {
@@ -63,9 +327,242 @@
     return false;
 }
 
-UpdateStatus SnapshotManager::GetUpdateStatus(double* progress) {
-    *progress = 0.0f;
-    return UpdateStatus::None;
+bool SnapshotManager::RemoveAllSnapshots(LockedFile* lock) {
+    std::vector<std::string> snapshots;
+    if (!ListSnapshots(lock, &snapshots)) {
+        LOG(ERROR) << "Could not list snapshots";
+        return false;
+    }
+
+    bool ok = true;
+    for (const auto& name : snapshots) {
+        ok &= DeleteSnapshot(lock, name);
+    }
+    return ok;
+}
+
+UpdateState SnapshotManager::GetUpdateState(double* progress) {
+    auto file = LockShared();
+    if (!file) {
+        return UpdateState::None;
+    }
+
+    auto state = ReadUpdateState(file.get());
+    if (progress) {
+        *progress = 0.0;
+        if (state == UpdateState::Merging) {
+            // :TODO: When merging is implemented, set progress_val.
+        } else if (state == UpdateState::MergeCompleted) {
+            *progress = 100.0;
+        }
+    }
+    return state;
+}
+
+bool SnapshotManager::ListSnapshots(LockedFile* lock, std::vector<std::string>* snapshots) {
+    CHECK(lock);
+
+    auto dir_path = metadata_dir_ + "/snapshots"s;
+    std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(dir_path.c_str()), closedir);
+    if (!dir) {
+        PLOG(ERROR) << "opendir failed: " << dir_path;
+        return false;
+    }
+
+    struct dirent* dp;
+    while ((dp = readdir(dir.get())) != nullptr) {
+        if (dp->d_type != DT_REG) continue;
+        snapshots->emplace_back(dp->d_name);
+    }
+    return true;
+}
+
+auto SnapshotManager::OpenFile(const std::string& file, int open_flags, int lock_flags)
+        -> std::unique_ptr<LockedFile> {
+    unique_fd fd(open(file.c_str(), open_flags | O_CLOEXEC | O_NOFOLLOW | O_SYNC, 0660));
+    if (fd < 0) {
+        PLOG(ERROR) << "Open failed: " << file;
+        return nullptr;
+    }
+    if (flock(fd, lock_flags) < 0) {
+        PLOG(ERROR) << "Acquire flock failed: " << file;
+        return nullptr;
+    }
+    return std::make_unique<LockedFile>(file, std::move(fd));
+}
+
+SnapshotManager::LockedFile::~LockedFile() {
+    if (flock(fd_, LOCK_UN) < 0) {
+        PLOG(ERROR) << "Failed to unlock file: " << path_;
+    }
+}
+
+std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::OpenStateFile(int open_flags,
+                                                                            int lock_flags) {
+    auto state_file = metadata_dir_ + "/state"s;
+    return OpenFile(state_file, open_flags, lock_flags);
+}
+
+std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::LockShared() {
+    return OpenStateFile(O_RDONLY, LOCK_SH);
+}
+
+std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::LockExclusive() {
+    return OpenStateFile(O_RDWR | O_CREAT, LOCK_EX);
+}
+
+UpdateState SnapshotManager::ReadUpdateState(LockedFile* file) {
+    // Reset position since some calls read+write.
+    if (lseek(file->fd(), 0, SEEK_SET) < 0) {
+        PLOG(ERROR) << "lseek state file failed";
+        return UpdateState::None;
+    }
+
+    std::string contents;
+    if (!android::base::ReadFdToString(file->fd(), &contents)) {
+        PLOG(ERROR) << "Read state file failed";
+        return UpdateState::None;
+    }
+
+    if (contents.empty() || contents == "none") {
+        return UpdateState::None;
+    } else if (contents == "initiated") {
+        return UpdateState::Initiated;
+    } else if (contents == "unverified") {
+        return UpdateState::Unverified;
+    } else if (contents == "merging") {
+        return UpdateState::Merging;
+    } else if (contents == "merge-completed") {
+        return UpdateState::MergeCompleted;
+    } else {
+        LOG(ERROR) << "Unknown merge state in update state file";
+        return UpdateState::None;
+    }
+}
+
+bool SnapshotManager::WriteUpdateState(LockedFile* file, UpdateState state) {
+    std::string contents;
+    switch (state) {
+        case UpdateState::None:
+            contents = "none";
+            break;
+        case UpdateState::Initiated:
+            contents = "initiated";
+            break;
+        case UpdateState::Unverified:
+            contents = "unverified";
+            break;
+        case UpdateState::Merging:
+            contents = "merging";
+            break;
+        case UpdateState::MergeCompleted:
+            contents = "merge-completed";
+            break;
+        default:
+            LOG(ERROR) << "Unknown update state";
+            return false;
+    }
+
+    if (!Truncate(file)) return false;
+    if (!android::base::WriteStringToFd(contents, file->fd())) {
+        PLOG(ERROR) << "Could not write to state file";
+        return false;
+    }
+    return true;
+}
+
+auto SnapshotManager::OpenSnapshotStatusFile(const std::string& name, int open_flags,
+                                             int lock_flags) -> std::unique_ptr<LockedFile> {
+    auto file = metadata_dir_ + "/snapshots/"s + name;
+    return OpenFile(file, open_flags, lock_flags);
+}
+
+bool SnapshotManager::ReadSnapshotStatus(LockedFile* file, SnapshotStatus* status) {
+    // Reset position since some calls read+write.
+    if (lseek(file->fd(), 0, SEEK_SET) < 0) {
+        PLOG(ERROR) << "lseek status file failed";
+        return false;
+    }
+
+    std::string contents;
+    if (!android::base::ReadFdToString(file->fd(), &contents)) {
+        PLOG(ERROR) << "read status file failed";
+        return false;
+    }
+    auto pieces = android::base::Split(contents, " ");
+    if (pieces.size() != 5) {
+        LOG(ERROR) << "Invalid status line for snapshot: " << file->path();
+        return false;
+    }
+
+    status->state = pieces[0];
+    if (!android::base::ParseUint(pieces[1], &status->device_size)) {
+        LOG(ERROR) << "Invalid device size in status line for: " << file->path();
+        return false;
+    }
+    if (!android::base::ParseUint(pieces[2], &status->snapshot_size)) {
+        LOG(ERROR) << "Invalid snapshot size in status line for: " << file->path();
+        return false;
+    }
+    if (!android::base::ParseUint(pieces[3], &status->sectors_allocated)) {
+        LOG(ERROR) << "Invalid snapshot size in status line for: " << file->path();
+        return false;
+    }
+    if (!android::base::ParseUint(pieces[4], &status->metadata_sectors)) {
+        LOG(ERROR) << "Invalid snapshot size in status line for: " << file->path();
+        return false;
+    }
+    return true;
+}
+
+bool SnapshotManager::WriteSnapshotStatus(LockedFile* file, const SnapshotStatus& status) {
+    std::vector<std::string> pieces = {
+            status.state,
+            std::to_string(status.device_size),
+            std::to_string(status.snapshot_size),
+            std::to_string(status.sectors_allocated),
+            std::to_string(status.metadata_sectors),
+    };
+    auto contents = android::base::Join(pieces, " ");
+
+    if (!Truncate(file)) return false;
+    if (!android::base::WriteStringToFd(contents, file->fd())) {
+        PLOG(ERROR) << "write to status file failed: " << file->path();
+        return false;
+    }
+    return true;
+}
+
+bool SnapshotManager::Truncate(LockedFile* file) {
+    if (lseek(file->fd(), 0, SEEK_SET) < 0) {
+        PLOG(ERROR) << "lseek file failed: " << file->path();
+        return false;
+    }
+    if (ftruncate(file->fd(), 0) < 0) {
+        PLOG(ERROR) << "truncate failed: " << file->path();
+        return false;
+    }
+    return true;
+}
+
+std::string SnapshotManager::GetSnapshotDeviceName(const std::string& snapshot_name,
+                                                   const SnapshotStatus& status) {
+    if (status.device_size != status.snapshot_size) {
+        return snapshot_name + "-inner";
+    }
+    return snapshot_name;
+}
+
+bool SnapshotManager::EnsureImageManager() {
+    if (images_) return true;
+
+    // For now, use a preset timeout.
+    images_ = android::fiemap::IImageManager::Open(gsid_dir_, 15000ms);
+    if (!images_) {
+        LOG(ERROR) << "Could not open ImageManager";
+        return false;
+    }
+    return true;
 }
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
new file mode 100644
index 0000000..9cc9bd7
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -0,0 +1,191 @@
+// Copyright (C) 2018 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 <libsnapshot/snapshot.h>
+
+#include <fcntl.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <chrono>
+#include <iostream>
+
+#include <android-base/strings.h>
+#include <gtest/gtest.h>
+#include <libfiemap/image_manager.h>
+
+namespace android {
+namespace snapshot {
+
+using namespace std::chrono_literals;
+using namespace std::string_literals;
+
+class TestDeviceInfo : public SnapshotManager::IDeviceInfo {
+  public:
+    std::string GetGsidDir() const override { return "ota/test"s; }
+    std::string GetMetadataDir() const override { return "/metadata/ota/test"s; }
+    bool IsRunningSnapshot() const override { return is_running_snapshot_; }
+
+    void set_is_running_snapshot(bool value) { is_running_snapshot_ = value; }
+
+  private:
+    bool is_running_snapshot_;
+};
+
+std::unique_ptr<SnapshotManager> sm;
+TestDeviceInfo* test_device = nullptr;
+
+class SnapshotTest : public ::testing::Test {
+  protected:
+    void SetUp() override {
+        test_device->set_is_running_snapshot(false);
+
+        if (sm->GetUpdateState() != UpdateState::None) {
+            ASSERT_TRUE(sm->CancelUpdate());
+        }
+        ASSERT_TRUE(sm->BeginUpdate());
+        ASSERT_TRUE(sm->EnsureImageManager());
+
+        image_manager_ = sm->image_manager();
+        ASSERT_NE(image_manager_, nullptr);
+    }
+
+    void TearDown() override {
+        lock_ = nullptr;
+
+        if (sm->GetUpdateState() != UpdateState::None) {
+            ASSERT_TRUE(sm->CancelUpdate());
+        }
+        for (const auto& temp_image : temp_images_) {
+            image_manager_->UnmapImageDevice(temp_image);
+            image_manager_->DeleteBackingImage(temp_image);
+        }
+    }
+
+    bool AcquireLock() {
+        lock_ = sm->OpenStateFile(O_RDWR, LOCK_EX);
+        return !!lock_;
+    }
+
+    bool CreateTempDevice(const std::string& name, uint64_t size, std::string* path) {
+        if (!image_manager_->CreateBackingImage(name, size, false)) {
+            return false;
+        }
+        temp_images_.emplace_back(name);
+        return image_manager_->MapImageDevice(name, 10s, path);
+    }
+
+    std::unique_ptr<SnapshotManager::LockedFile> lock_;
+    std::vector<std::string> temp_images_;
+    android::fiemap::IImageManager* image_manager_ = nullptr;
+};
+
+TEST_F(SnapshotTest, CreateSnapshot) {
+    ASSERT_TRUE(AcquireLock());
+
+    static const uint64_t kDeviceSize = 1024 * 1024;
+    ASSERT_TRUE(sm->CreateSnapshot(lock_.get(), "test-snapshot", kDeviceSize, kDeviceSize,
+                                   kDeviceSize));
+
+    std::vector<std::string> snapshots;
+    ASSERT_TRUE(sm->ListSnapshots(lock_.get(), &snapshots));
+    ASSERT_EQ(snapshots.size(), 1);
+    ASSERT_EQ(snapshots[0], "test-snapshot");
+
+    // Scope so delete can re-acquire the snapshot file lock.
+    {
+        auto file = sm->OpenSnapshotStatusFile("test-snapshot", O_RDONLY, LOCK_SH);
+        ASSERT_NE(file, nullptr);
+
+        SnapshotManager::SnapshotStatus status;
+        ASSERT_TRUE(sm->ReadSnapshotStatus(file.get(), &status));
+        ASSERT_EQ(status.state, "created");
+        ASSERT_EQ(status.device_size, kDeviceSize);
+        ASSERT_EQ(status.snapshot_size, kDeviceSize);
+    }
+
+    ASSERT_TRUE(sm->UnmapSnapshot(lock_.get(), "test-snapshot"));
+    ASSERT_TRUE(sm->DeleteSnapshot(lock_.get(), "test-snapshot"));
+}
+
+TEST_F(SnapshotTest, MapSnapshot) {
+    ASSERT_TRUE(AcquireLock());
+
+    static const uint64_t kDeviceSize = 1024 * 1024;
+    ASSERT_TRUE(sm->CreateSnapshot(lock_.get(), "test-snapshot", kDeviceSize, kDeviceSize,
+                                   kDeviceSize));
+
+    std::string base_device;
+    ASSERT_TRUE(CreateTempDevice("base-device", kDeviceSize, &base_device));
+
+    std::string snap_device;
+    ASSERT_TRUE(sm->MapSnapshot(lock_.get(), "test-snapshot", base_device, 10s, &snap_device));
+    ASSERT_TRUE(android::base::StartsWith(snap_device, "/dev/block/dm-"));
+}
+
+TEST_F(SnapshotTest, MapPartialSnapshot) {
+    ASSERT_TRUE(AcquireLock());
+
+    static const uint64_t kSnapshotSize = 1024 * 1024;
+    static const uint64_t kDeviceSize = 1024 * 1024 * 2;
+    ASSERT_TRUE(sm->CreateSnapshot(lock_.get(), "test-snapshot", kDeviceSize, kSnapshotSize,
+                                   kSnapshotSize));
+
+    std::string base_device;
+    ASSERT_TRUE(CreateTempDevice("base-device", kDeviceSize, &base_device));
+
+    std::string snap_device;
+    ASSERT_TRUE(sm->MapSnapshot(lock_.get(), "test-snapshot", base_device, 10s, &snap_device));
+    ASSERT_TRUE(android::base::StartsWith(snap_device, "/dev/block/dm-"));
+}
+
+}  // namespace snapshot
+}  // namespace android
+
+using namespace android::snapshot;
+
+bool Mkdir(const std::string& path) {
+    if (mkdir(path.c_str(), 0700) && errno != EEXIST) {
+        std::cerr << "Could not mkdir " << path << ": " << strerror(errno) << std::endl;
+        return false;
+    }
+    return true;
+}
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+
+    std::vector<std::string> paths = {
+            "/data/gsi/ota/test",
+            "/metadata/gsi/ota/test",
+            "/metadata/ota/test",
+            "/metadata/ota/test/snapshots",
+    };
+    for (const auto& path : paths) {
+        if (!Mkdir(path)) {
+            return 1;
+        }
+    }
+
+    // Create this once, otherwise, gsid will start/stop between each test.
+    test_device = new TestDeviceInfo();
+    sm = SnapshotManager::New(test_device);
+    if (!sm) {
+        std::cerr << "Could not create snapshot manager";
+        return 1;
+    }
+
+    return RUN_ALL_TESTS();
+}
diff --git a/fs_mgr/tools/dmctl.cpp b/fs_mgr/tools/dmctl.cpp
index 4fb0b83..2738457 100644
--- a/fs_mgr/tools/dmctl.cpp
+++ b/fs_mgr/tools/dmctl.cpp
@@ -197,19 +197,12 @@
     char** argv_;
 };
 
-static int DmCreateCmdHandler(int argc, char** argv) {
-    if (argc < 1) {
-        std::cerr << "Usage: dmctl create <dm-name> [-ro] <targets...>" << std::endl;
-        return -EINVAL;
-    }
-    std::string name = argv[0];
-
+static bool parse_table_args(DmTable* table, int argc, char** argv) {
     // Parse extended options first.
-    DmTable table;
     int arg_index = 1;
     while (arg_index < argc && argv[arg_index][0] == '-') {
         if (strcmp(argv[arg_index], "-ro") == 0) {
-            table.set_readonly(true);
+            table->set_readonly(true);
             arg_index++;
         } else {
             std::cerr << "Unrecognized option: " << argv[arg_index] << std::endl;
@@ -221,15 +214,30 @@
     TargetParser parser(argc - arg_index, argv + arg_index);
     while (parser.More()) {
         std::unique_ptr<DmTarget> target = parser.Next();
-        if (!target || !table.AddTarget(std::move(target))) {
+        if (!target || !table->AddTarget(std::move(target))) {
             return -EINVAL;
         }
     }
 
-    if (table.num_targets() == 0) {
+    if (table->num_targets() == 0) {
         std::cerr << "Must define at least one target." << std::endl;
         return -EINVAL;
     }
+    return 0;
+}
+
+static int DmCreateCmdHandler(int argc, char** argv) {
+    if (argc < 1) {
+        std::cerr << "Usage: dmctl create <dm-name> [-ro] <targets...>" << std::endl;
+        return -EINVAL;
+    }
+    std::string name = argv[0];
+
+    DmTable table;
+    int ret = parse_table_args(&table, argc, argv);
+    if (ret) {
+        return ret;
+    }
 
     DeviceMapper& dm = DeviceMapper::Instance();
     if (!dm.CreateDevice(name, table)) {
@@ -255,6 +263,27 @@
     return 0;
 }
 
+static int DmReplaceCmdHandler(int argc, char** argv) {
+    if (argc < 1) {
+        std::cerr << "Usage: dmctl replace <dm-name> <targets...>" << std::endl;
+        return -EINVAL;
+    }
+    std::string name = argv[0];
+
+    DmTable table;
+    int ret = parse_table_args(&table, argc, argv);
+    if (ret) {
+        return ret;
+    }
+
+    DeviceMapper& dm = DeviceMapper::Instance();
+    if (!dm.LoadTableAndActivate(name, table)) {
+        std::cerr << "Failed to replace device-mapper table to: " << name << std::endl;
+        return -EIO;
+    }
+    return 0;
+}
+
 static int DmListTargets(DeviceMapper& dm, [[maybe_unused]] int argc,
                          [[maybe_unused]] char** argv) {
     std::vector<DmTargetTypeInfo> targets;
@@ -469,6 +498,7 @@
         // clang-format off
         {"create", DmCreateCmdHandler},
         {"delete", DmDeleteCmdHandler},
+        {"replace", DmReplaceCmdHandler},
         {"list", DmListCmdHandler},
         {"help", HelpCmdHandler},
         {"getpath", GetPathCmdHandler},
diff --git a/init/Android.bp b/init/Android.bp
index ba60085..3233cc3 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -83,6 +83,7 @@
         "libfscrypt",
         "libgsi",
         "libhidl-gen-utils",
+        "libjsoncpp",
         "libkeyutils",
         "liblog",
         "liblogwrap",
@@ -93,12 +94,16 @@
         "libutils",
     ],
     bootstrap: true,
+    visibility: [":__subpackages__"],
 }
 
 cc_library_static {
     name: "libinit",
     recovery_available: true,
-    defaults: ["init_defaults", "selinux_policy_version"],
+    defaults: [
+        "init_defaults",
+        "selinux_policy_version",
+    ],
     srcs: [
         "action.cpp",
         "action_manager.cpp",
@@ -114,6 +119,7 @@
         "first_stage_mount.cpp",
         "import_parser.cpp",
         "init.cpp",
+        "interface_utils.cpp",
         "keychords.cpp",
         "modalias_handler.cpp",
         "mount_handler.cpp",
@@ -143,7 +149,10 @@
         "ueventd_parser.cpp",
         "util.cpp",
     ],
-    whole_static_libs: ["libcap", "com.android.sysprop.apex"],
+    whole_static_libs: [
+        "libcap",
+        "com.android.sysprop.apex",
+    ],
     header_libs: ["bootimg_headers"],
     proto: {
         type: "lite",
@@ -153,7 +162,10 @@
     target: {
         recovery: {
             cflags: ["-DRECOVERY"],
-            exclude_shared_libs: ["libbinder", "libutils"],
+            exclude_shared_libs: [
+                "libbinder",
+                "libutils",
+            ],
         },
     },
 }
@@ -182,7 +194,10 @@
     target: {
         recovery: {
             cflags: ["-DRECOVERY"],
-            exclude_shared_libs: ["libbinder", "libutils"],
+            exclude_shared_libs: [
+                "libbinder",
+                "libutils",
+            ],
         },
     },
 }
@@ -227,9 +242,13 @@
 
 genrule {
     name: "generated_stub_builtin_function_map",
+    tool_files: ["host_builtin_map.py"],
     out: ["generated_stub_builtin_function_map.h"],
-    srcs: ["builtins.cpp"],
-    cmd: "sed -n '/Builtin-function-map start/{:a;n;/Builtin-function-map end/q;p;ba}' $(in) | sed -e 's/do_[^}]*/do_stub/g' > $(out)",
+    srcs: [
+        "builtins.cpp",
+        "check_builtins.cpp",
+    ],
+    cmd: "$(location host_builtin_map.py) --builtins $(location builtins.cpp) --check_builtins $(location check_builtins.cpp) > $(out)",
 }
 
 cc_binary {
@@ -260,9 +279,11 @@
         "action_manager.cpp",
         "action_parser.cpp",
         "capabilities.cpp",
+        "check_builtins.cpp",
         "epoll.cpp",
         "keychords.cpp",
         "import_parser.cpp",
+        "interface_utils.cpp",
         "host_import_parser.cpp",
         "host_init_verifier.cpp",
         "parser.cpp",
@@ -281,7 +302,7 @@
     },
     generated_headers: [
         "generated_stub_builtin_function_map",
-        "generated_android_ids"
+        "generated_android_ids",
     ],
     target: {
         android: {
diff --git a/init/action.cpp b/init/action.cpp
index 0c476df..1a66eee 100644
--- a/init/action.cpp
+++ b/init/action.cpp
@@ -35,9 +35,11 @@
     builtin_arguments.args.resize(args.size());
     builtin_arguments.args[0] = args[0];
     for (std::size_t i = 1; i < args.size(); ++i) {
-        if (!expand_props(args[i], &builtin_arguments.args[i])) {
-            return Error() << "cannot expand '" << args[i] << "'";
+        auto expanded_arg = ExpandProps(args[i]);
+        if (!expanded_arg) {
+            return expanded_arg.error();
         }
+        builtin_arguments.args[i] = std::move(*expanded_arg);
     }
 
     return function(builtin_arguments);
@@ -66,6 +68,30 @@
     return RunBuiltinFunction(func_, args_, kInitContext);
 }
 
+Result<void> Command::CheckCommand() const {
+    auto builtin_arguments = BuiltinArguments("host_init_verifier");
+
+    builtin_arguments.args.resize(args_.size());
+    builtin_arguments.args[0] = args_[0];
+    for (size_t i = 1; i < args_.size(); ++i) {
+        auto expanded_arg = ExpandProps(args_[i]);
+        if (!expanded_arg) {
+            if (expanded_arg.error().message().find("doesn't exist while expanding") !=
+                std::string::npos) {
+                // If we failed because we won't have a property, use an empty string, which is
+                // never returned from the parser, to indicate that this field cannot be checked.
+                builtin_arguments.args[i] = "";
+            } else {
+                return expanded_arg.error();
+            }
+        } else {
+            builtin_arguments.args[i] = std::move(*expanded_arg);
+        }
+    }
+
+    return func_(builtin_arguments);
+}
+
 std::string Command::BuildCommandString() const {
     return Join(args_, ' ');
 }
@@ -105,6 +131,18 @@
     return commands_.size();
 }
 
+size_t Action::CheckAllCommands() const {
+    size_t failures = 0;
+    for (const auto& command : commands_) {
+        if (auto result = command.CheckCommand(); !result) {
+            LOG(ERROR) << "Command '" << command.BuildCommandString() << "' (" << filename_ << ":"
+                       << command.line() << ") failed: " << result.error();
+            ++failures;
+        }
+    }
+    return failures;
+}
+
 void Action::ExecuteOneCommand(std::size_t command) const {
     // We need a copy here since some Command execution may result in
     // changing commands_ vector by importing .rc files through parser
@@ -123,18 +161,8 @@
     auto result = command.InvokeFunc(subcontext_);
     auto duration = t.duration();
 
-    // There are many legacy paths in rootdir/init.rc that will virtually never exist on a new
-    // device, such as '/sys/class/leds/jogball-backlight/brightness'.  As of this writing, there
-    // are 198 such failures on bullhead.  Instead of spamming the log reporting them, we do not
-    // report such failures unless we're running at the DEBUG log level.
-    bool report_failure = !result.has_value();
-    if (report_failure && android::base::GetMinimumLogSeverity() > android::base::DEBUG &&
-        result.error().code() == ENOENT) {
-        report_failure = false;
-    }
-
     // Any action longer than 50ms will be warned to user as slow operation
-    if (report_failure || duration > 50ms ||
+    if (!result.has_value() || duration > 50ms ||
         android::base::GetMinimumLogSeverity() <= android::base::DEBUG) {
         std::string trigger_name = BuildTriggersString();
         std::string cmd_str = command.BuildCommandString();
diff --git a/init/action.h b/init/action.h
index 80c1da4..1534bf9 100644
--- a/init/action.h
+++ b/init/action.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _INIT_ACTION_H
-#define _INIT_ACTION_H
+#pragma once
 
 #include <map>
 #include <queue>
@@ -41,6 +40,7 @@
 
     Result<void> InvokeFunc(Subcontext* subcontext) const;
     std::string BuildCommandString() const;
+    Result<void> CheckCommand() const;
 
     int line() const { return line_; }
 
@@ -63,7 +63,7 @@
 
     Result<void> AddCommand(std::vector<std::string>&& args, int line);
     void AddCommand(BuiltinFunction f, std::vector<std::string>&& args, int line);
-    std::size_t NumCommands() const;
+    size_t NumCommands() const;
     void ExecuteOneCommand(std::size_t command) const;
     void ExecuteAllCommands() const;
     bool CheckEvent(const EventTrigger& event_trigger) const;
@@ -71,6 +71,7 @@
     bool CheckEvent(const BuiltinAction& builtin_action) const;
     std::string BuildTriggersString() const;
     void DumpState() const;
+    size_t CheckAllCommands() const;
 
     bool oneshot() const { return oneshot_; }
     const std::string& filename() const { return filename_; }
@@ -96,5 +97,3 @@
 
 }  // namespace init
 }  // namespace android
-
-#endif
diff --git a/init/action_manager.cpp b/init/action_manager.cpp
index 541c8f2..ebca762 100644
--- a/init/action_manager.cpp
+++ b/init/action_manager.cpp
@@ -23,6 +23,14 @@
 
 ActionManager::ActionManager() : current_command_(0) {}
 
+size_t ActionManager::CheckAllCommands() {
+    size_t failures = 0;
+    for (const auto& action : actions_) {
+        failures += action->CheckAllCommands();
+    }
+    return failures;
+}
+
 ActionManager& ActionManager::GetInstance() {
     static ActionManager instance;
     return instance;
diff --git a/init/action_manager.h b/init/action_manager.h
index 5f47a6d..a2b95ac 100644
--- a/init/action_manager.h
+++ b/init/action_manager.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _INIT_ACTION_MANAGER_H
-#define _INIT_ACTION_MANAGER_H
+#pragma once
 
 #include <string>
 #include <vector>
@@ -32,6 +31,7 @@
 
     // Exposed for testing
     ActionManager();
+    size_t CheckAllCommands();
 
     void AddAction(std::unique_ptr<Action> action);
     void QueueEventTrigger(const std::string& trigger);
@@ -55,5 +55,3 @@
 
 }  // namespace init
 }  // namespace android
-
-#endif
diff --git a/init/builtins.cpp b/init/builtins.cpp
index b6e26a1..a2d782b 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -89,6 +89,43 @@
 namespace android {
 namespace init {
 
+// There are many legacy paths in rootdir/init.rc that will virtually never exist on a new
+// device, such as '/sys/class/leds/jogball-backlight/brightness'.  As of this writing, there
+// are 81 such failures on cuttlefish.  Instead of spamming the log reporting them, we do not
+// report such failures unless we're running at the DEBUG log level.
+class ErrorIgnoreEnoent {
+  public:
+    ErrorIgnoreEnoent()
+        : ignore_error_(errno == ENOENT &&
+                        android::base::GetMinimumLogSeverity() > android::base::DEBUG) {}
+    explicit ErrorIgnoreEnoent(int errno_to_append)
+        : error_(errno_to_append),
+          ignore_error_(errno_to_append == ENOENT &&
+                        android::base::GetMinimumLogSeverity() > android::base::DEBUG) {}
+
+    template <typename T>
+    operator android::base::expected<T, ResultError>() {
+        if (ignore_error_) {
+            return {};
+        }
+        return error_;
+    }
+
+    template <typename T>
+    ErrorIgnoreEnoent& operator<<(T&& t) {
+        error_ << t;
+        return *this;
+    }
+
+  private:
+    Error error_;
+    bool ignore_error_;
+};
+
+inline ErrorIgnoreEnoent ErrnoErrorIgnoreEnoent() {
+    return ErrorIgnoreEnoent(errno);
+}
+
 std::vector<std::string> late_import_paths;
 
 static constexpr std::chrono::nanoseconds kCommandRetryTimeout = 5s;
@@ -201,26 +238,26 @@
 static Result<void> do_exec(const BuiltinArguments& args) {
     auto service = Service::MakeTemporaryOneshotService(args.args);
     if (!service) {
-        return Error() << "Could not create exec service";
+        return Error() << "Could not create exec service: " << service.error();
     }
-    if (auto result = service->ExecStart(); !result) {
+    if (auto result = (*service)->ExecStart(); !result) {
         return Error() << "Could not start exec service: " << result.error();
     }
 
-    ServiceList::GetInstance().AddService(std::move(service));
+    ServiceList::GetInstance().AddService(std::move(*service));
     return {};
 }
 
 static Result<void> do_exec_background(const BuiltinArguments& args) {
     auto service = Service::MakeTemporaryOneshotService(args.args);
     if (!service) {
-        return Error() << "Could not create exec background service";
+        return Error() << "Could not create exec background service: " << service.error();
     }
-    if (auto result = service->Start(); !result) {
+    if (auto result = (*service)->Start(); !result) {
         return Error() << "Could not start exec background service: " << result.error();
     }
 
-    ServiceList::GetInstance().AddService(std::move(service));
+    ServiceList::GetInstance().AddService(std::move(*service));
     return {};
 }
 
@@ -330,7 +367,7 @@
                 return ErrnoError() << "fchmodat() failed";
             }
         } else {
-            return ErrnoError() << "mkdir() failed";
+            return ErrnoErrorIgnoreEnoent() << "mkdir() failed";
         }
     }
 
@@ -344,7 +381,7 @@
         if (args.size() == 5) {
             gid = DecodeUid(args[4]);
             if (!gid) {
-                return Error() << "Unable to decode GID for '" << args[3] << "': " << gid.error();
+                return Error() << "Unable to decode GID for '" << args[4] << "': " << gid.error();
             }
         }
 
@@ -459,7 +496,7 @@
         if (wait)
             wait_for_file(source, kCommandRetryTimeout);
         if (mount(source, target, system, flags, options) < 0) {
-            return ErrnoError() << "mount() failed";
+            return ErrnoErrorIgnoreEnoent() << "mount() failed";
         }
 
     }
@@ -683,7 +720,7 @@
     Service* svc = ServiceList::GetInstance().FindService(args[1]);
     if (!svc) return Error() << "service " << args[1] << " not found";
     if (auto result = svc->Start(); !result) {
-        return Error() << "Could not start service: " << result.error();
+        return ErrorIgnoreEnoent() << "Could not start service: " << result.error();
     }
     return {};
 }
@@ -729,10 +766,7 @@
     if (MakeSymlink(args[1], args[2]) < 0) {
         // The symlink builtin is often used to create symlinks for older devices to be backwards
         // compatible with new paths, therefore we skip reporting this error.
-        if (errno == EEXIST && android::base::GetMinimumLogSeverity() > android::base::DEBUG) {
-            return {};
-        }
-        return ErrnoError() << "symlink() failed";
+        return ErrnoErrorIgnoreEnoent() << "symlink() failed";
     }
     return {};
 }
@@ -790,7 +824,8 @@
 
 static Result<void> do_write(const BuiltinArguments& args) {
     if (auto result = WriteFile(args[1], args[2]); !result) {
-        return Error() << "Unable to write to file '" << args[1] << "': " << result.error();
+        return ErrorIgnoreEnoent()
+               << "Unable to write to file '" << args[1] << "': " << result.error();
     }
 
     return {};
@@ -908,7 +943,7 @@
     }
 
     if (lchown(path.c_str(), *uid, *gid) == -1) {
-        return ErrnoError() << "lchown() failed";
+        return ErrnoErrorIgnoreEnoent() << "lchown() failed";
     }
 
     return {};
@@ -930,50 +965,27 @@
 static Result<void> do_chmod(const BuiltinArguments& args) {
     mode_t mode = get_mode(args[1].c_str());
     if (fchmodat(AT_FDCWD, args[2].c_str(), mode, AT_SYMLINK_NOFOLLOW) < 0) {
-        return ErrnoError() << "fchmodat() failed";
+        return ErrnoErrorIgnoreEnoent() << "fchmodat() failed";
     }
     return {};
 }
 
 static Result<void> do_restorecon(const BuiltinArguments& args) {
+    auto restorecon_info = ParseRestorecon(args.args);
+    if (!restorecon_info) {
+        return restorecon_info.error();
+    }
+
+    const auto& [flag, paths] = *restorecon_info;
+
     int ret = 0;
-
-    struct flag_type {const char* name; int value;};
-    static const flag_type flags[] = {
-        {"--recursive", SELINUX_ANDROID_RESTORECON_RECURSE},
-        {"--skip-ce", SELINUX_ANDROID_RESTORECON_SKIPCE},
-        {"--cross-filesystems", SELINUX_ANDROID_RESTORECON_CROSS_FILESYSTEMS},
-        {0, 0}
-    };
-
-    int flag = 0;
-
-    bool in_flags = true;
-    for (size_t i = 1; i < args.size(); ++i) {
-        if (android::base::StartsWith(args[i], "--")) {
-            if (!in_flags) {
-                return Error() << "flags must precede paths";
-            }
-            bool found = false;
-            for (size_t j = 0; flags[j].name; ++j) {
-                if (args[i] == flags[j].name) {
-                    flag |= flags[j].value;
-                    found = true;
-                    break;
-                }
-            }
-            if (!found) {
-                return Error() << "bad flag " << args[i];
-            }
-        } else {
-            in_flags = false;
-            if (selinux_android_restorecon(args[i].c_str(), flag) < 0) {
-                ret = errno;
-            }
+    for (const auto& path : paths) {
+        if (selinux_android_restorecon(path.c_str(), flag) < 0) {
+            ret = errno;
         }
     }
 
-    if (ret) return ErrnoError() << "selinux_android_restorecon() failed";
+    if (ret) return ErrnoErrorIgnoreEnoent() << "selinux_android_restorecon() failed";
     return {};
 }
 
@@ -1056,9 +1068,9 @@
                                             const BuiltinArguments& args) {
     auto service = Service::MakeTemporaryOneshotService(args.args);
     if (!service) {
-        return Error() << "Could not create exec service";
+        return Error() << "Could not create exec service: " << service.error();
     }
-    service->AddReapCallback([reboot_reason](const siginfo_t& siginfo) {
+    (*service)->AddReapCallback([reboot_reason](const siginfo_t& siginfo) {
         if (siginfo.si_code != CLD_EXITED || siginfo.si_status != 0) {
             // TODO (b/122850122): support this in gsi
             if (fscrypt_is_native() && !android::gsi::IsGsiRunning()) {
@@ -1073,10 +1085,10 @@
             }
         }
     });
-    if (auto result = service->ExecStart(); !result) {
+    if (auto result = (*service)->ExecStart(); !result) {
         return Error() << "Could not start exec service: " << result.error();
     }
-    ServiceList::GetInstance().AddService(std::move(service));
+    ServiceList::GetInstance().AddService(std::move(*service));
     return {};
 }
 
diff --git a/init/check_builtins.cpp b/init/check_builtins.cpp
new file mode 100644
index 0000000..771f1d7
--- /dev/null
+++ b/init/check_builtins.cpp
@@ -0,0 +1,213 @@
+/*
+ * 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.
+ */
+
+// Note that these check functions cannot check expanded arguments from properties, since they will
+// not know what those properties would be at runtime.  They will be passed an empty string in the
+// situation that the input line had a property expansion without a default value, since an empty
+// string is otherwise an impossible value.  They should therefore disregard checking empty
+// arguments.
+
+#include "check_builtins.h"
+
+#include <sys/time.h>
+
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/strings.h>
+
+#include "builtin_arguments.h"
+#include "interface_utils.h"
+#include "rlimit_parser.h"
+#include "service.h"
+#include "util.h"
+
+using android::base::ParseInt;
+using android::base::StartsWith;
+
+#define ReturnIfAnyArgsEmpty()     \
+    for (const auto& arg : args) { \
+        if (arg.empty()) {         \
+            return {};             \
+        }                          \
+    }
+
+namespace android {
+namespace init {
+
+Result<void> check_chown(const BuiltinArguments& args) {
+    if (!args[1].empty()) {
+        auto uid = DecodeUid(args[1]);
+        if (!uid) {
+            return Error() << "Unable to decode UID for '" << args[1] << "': " << uid.error();
+        }
+    }
+
+    // GID is optional and pushes the index of path out by one if specified.
+    if (args.size() == 4 && !args[2].empty()) {
+        auto gid = DecodeUid(args[2]);
+        if (!gid) {
+            return Error() << "Unable to decode GID for '" << args[2] << "': " << gid.error();
+        }
+    }
+
+    return {};
+}
+
+Result<void> check_exec(const BuiltinArguments& args) {
+    ReturnIfAnyArgsEmpty();
+
+    auto result = Service::MakeTemporaryOneshotService(args.args);
+    if (!result) {
+        return result.error();
+    }
+
+    return {};
+}
+
+Result<void> check_exec_background(const BuiltinArguments& args) {
+    return check_exec(std::move(args));
+}
+
+Result<void> check_interface_restart(const BuiltinArguments& args) {
+    if (auto result = IsKnownInterface(args[1]); !result) {
+        return result.error();
+    }
+    return {};
+}
+
+Result<void> check_interface_start(const BuiltinArguments& args) {
+    return check_interface_restart(std::move(args));
+}
+
+Result<void> check_interface_stop(const BuiltinArguments& args) {
+    return check_interface_restart(std::move(args));
+}
+
+Result<void> check_load_system_props(const BuiltinArguments& args) {
+    return Error() << "'load_system_props' is deprecated";
+}
+
+Result<void> check_loglevel(const BuiltinArguments& args) {
+    ReturnIfAnyArgsEmpty();
+
+    int log_level = -1;
+    ParseInt(args[1], &log_level);
+    if (log_level < 0 || log_level > 7) {
+        return Error() << "loglevel must be in the range of 0-7";
+    }
+    return {};
+}
+
+Result<void> check_mkdir(const BuiltinArguments& args) {
+    if (args.size() >= 4) {
+        if (!args[3].empty()) {
+            auto uid = DecodeUid(args[3]);
+            if (!uid) {
+                return Error() << "Unable to decode UID for '" << args[3] << "': " << uid.error();
+            }
+        }
+
+        if (args.size() == 5 && !args[4].empty()) {
+            auto gid = DecodeUid(args[4]);
+            if (!gid) {
+                return Error() << "Unable to decode GID for '" << args[4] << "': " << gid.error();
+            }
+        }
+    }
+
+    return {};
+}
+
+Result<void> check_restorecon(const BuiltinArguments& args) {
+    ReturnIfAnyArgsEmpty();
+
+    auto restorecon_info = ParseRestorecon(args.args);
+    if (!restorecon_info) {
+        return restorecon_info.error();
+    }
+
+    return {};
+}
+
+Result<void> check_restorecon_recursive(const BuiltinArguments& args) {
+    return check_restorecon(std::move(args));
+}
+
+Result<void> check_setprop(const BuiltinArguments& args) {
+    const std::string& name = args[1];
+    if (name.empty()) {
+        return {};
+    }
+    const std::string& value = args[2];
+
+    if (!IsLegalPropertyName(name)) {
+        return Error() << "'" << name << "' is not a legal property name";
+    }
+
+    if (!value.empty()) {
+        if (auto result = IsLegalPropertyValue(name, value); !result) {
+            return result.error();
+        }
+    }
+
+    if (StartsWith(name, "ctl.")) {
+        return Error()
+               << "Do not set ctl. properties from init; call the Service functions directly";
+    }
+
+    static constexpr const char kRestoreconProperty[] = "selinux.restorecon_recursive";
+    if (name == kRestoreconProperty) {
+        return Error() << "Do not set '" << kRestoreconProperty
+                       << "' from init; use the restorecon builtin directly";
+    }
+
+    return {};
+}
+
+Result<void> check_setrlimit(const BuiltinArguments& args) {
+    ReturnIfAnyArgsEmpty();
+
+    auto rlimit = ParseRlimit(args.args);
+    if (!rlimit) return rlimit.error();
+    return {};
+}
+
+Result<void> check_sysclktz(const BuiltinArguments& args) {
+    ReturnIfAnyArgsEmpty();
+
+    struct timezone tz = {};
+    if (!android::base::ParseInt(args[1], &tz.tz_minuteswest)) {
+        return Error() << "Unable to parse mins_west_of_gmt";
+    }
+    return {};
+}
+
+Result<void> check_wait(const BuiltinArguments& args) {
+    if (args.size() == 3 && !args[2].empty()) {
+        int timeout_int;
+        if (!android::base::ParseInt(args[2], &timeout_int)) {
+            return Error() << "failed to parse timeout";
+        }
+    }
+    return {};
+}
+
+Result<void> check_wait_for_prop(const BuiltinArguments& args) {
+    return check_setprop(std::move(args));
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/check_builtins.h b/init/check_builtins.h
new file mode 100644
index 0000000..4ff0d0c
--- /dev/null
+++ b/init/check_builtins.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "builtin_arguments.h"
+#include "result.h"
+
+namespace android {
+namespace init {
+
+Result<void> check_chown(const BuiltinArguments& args);
+Result<void> check_exec(const BuiltinArguments& args);
+Result<void> check_exec_background(const BuiltinArguments& args);
+Result<void> check_interface_restart(const BuiltinArguments& args);
+Result<void> check_interface_start(const BuiltinArguments& args);
+Result<void> check_interface_stop(const BuiltinArguments& args);
+Result<void> check_load_system_props(const BuiltinArguments& args);
+Result<void> check_loglevel(const BuiltinArguments& args);
+Result<void> check_mkdir(const BuiltinArguments& args);
+Result<void> check_restorecon(const BuiltinArguments& args);
+Result<void> check_restorecon_recursive(const BuiltinArguments& args);
+Result<void> check_setprop(const BuiltinArguments& args);
+Result<void> check_setrlimit(const BuiltinArguments& args);
+Result<void> check_sysclktz(const BuiltinArguments& args);
+Result<void> check_wait(const BuiltinArguments& args);
+Result<void> check_wait_for_prop(const BuiltinArguments& args);
+
+}  // namespace init
+}  // namespace android
diff --git a/init/host_builtin_map.py b/init/host_builtin_map.py
new file mode 100755
index 0000000..6afcb17
--- /dev/null
+++ b/init/host_builtin_map.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+"""Generates the builtins map to be used by host_init_verifier.
+
+It copies the builtin function map from builtins.cpp, then replaces do_xxx() functions with the
+equivalent check_xxx() if found in check_builtins.cpp.
+
+"""
+
+import re
+import argparse
+
+parser = argparse.ArgumentParser('host_builtin_map.py')
+parser.add_argument('--builtins', required=True, help='Path to builtins.cpp')
+parser.add_argument('--check_builtins', required=True, help='Path to check_builtins.cpp')
+args = parser.parse_args()
+
+CHECK_REGEX = re.compile(r'.+check_(\S+)\(.+')
+check_functions = []
+with open(args.check_builtins) as check_file:
+  for line in check_file:
+    match = CHECK_REGEX.match(line)
+    if match:
+      check_functions.append(match.group(1))
+
+function_map = []
+with open(args.builtins) as builtins_file:
+  in_function_map = False
+  for line in builtins_file:
+    if '// Builtin-function-map start' in line:
+      in_function_map = True
+    elif '// Builtin-function-map end' in line:
+      in_function_map = False
+    elif in_function_map:
+      function_map.append(line)
+
+DO_REGEX = re.compile(r'.+do_([^\}]+).+')
+FUNCTION_REGEX = re.compile(r'(do_[^\}]+)')
+for line in function_map:
+  match = DO_REGEX.match(line)
+  if match:
+    if match.group(1) in check_functions:
+      print line.replace('do_', 'check_'),
+    else:
+      print FUNCTION_REGEX.sub('check_stub', line),
+  else:
+    print line,
diff --git a/init/host_init_stubs.h b/init/host_init_stubs.h
index 7c0544a..f9a08a5 100644
--- a/init/host_init_stubs.h
+++ b/init/host_init_stubs.h
@@ -26,6 +26,7 @@
 
 // android/api-level.h
 #define __ANDROID_API_P__ 28
+#define __ANDROID_API_R__ 30
 
 // sys/system_properties.h
 #define PROP_VALUE_MAX 92
diff --git a/init/host_init_verifier.cpp b/init/host_init_verifier.cpp
index dfde51b..b2402b3 100644
--- a/init/host_init_verifier.cpp
+++ b/init/host_init_verifier.cpp
@@ -30,13 +30,14 @@
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/strings.h>
-#include <json/json.h>
 
 #include "action.h"
 #include "action_manager.h"
 #include "action_parser.h"
+#include "check_builtins.h"
 #include "host_import_parser.h"
 #include "host_init_stubs.h"
+#include "interface_utils.h"
 #include "parser.h"
 #include "result.h"
 #include "service.h"
@@ -131,51 +132,22 @@
     return nullptr;
 }
 
-static std::optional<android::init::InterfaceInheritanceHierarchyMap>
-ReadInterfaceInheritanceHierarchy(const std::string& interface_inheritance_hierarchy_file) {
-    if (interface_inheritance_hierarchy_file.empty()) {
-        LOG(WARNING) << "Missing an interface inheritance hierarchy file.";
-        return {};
-    }
-
-    Json::Value root;
-    Json::Reader reader;
-    std::ifstream stream(interface_inheritance_hierarchy_file);
-    if (!reader.parse(stream, root)) {
-        LOG(ERROR) << "Failed to read interface inheritance hierarchy file: "
-                   << interface_inheritance_hierarchy_file << "\n"
-                   << reader.getFormattedErrorMessages();
-        return {};
-    }
-
-    android::init::InterfaceInheritanceHierarchyMap result;
-    for (const Json::Value& entry : root) {
-        std::set<std::string> inherited_interfaces;
-        for (const Json::Value& intf : entry["inheritedInterfaces"]) {
-            inherited_interfaces.insert(intf.asString());
-        }
-        result[entry["interface"].asString()] = inherited_interfaces;
-    }
-
-    return result;
-}
-
 namespace android {
 namespace init {
 
-static Result<void> do_stub(const BuiltinArguments& args) {
+static Result<void> check_stub(const BuiltinArguments& args) {
     return {};
 }
 
 #include "generated_stub_builtin_function_map.h"
 
 void PrintUsage() {
-    std::cout << "usage: host_init_verifier [-p FILE] -k FILE <init rc file>\n"
+    std::cout << "usage: host_init_verifier [-p FILE] -i FILE <init rc file>\n"
                  "\n"
                  "Tests an init script for correctness\n"
                  "\n"
                  "-p FILE\tSearch this passwd file for users and groups\n"
-                 "-k FILE\tUse this file as a space-separated list of known interfaces\n"
+                 "-i FILE\tParse this JSON file for the HIDL interface inheritance hierarchy\n"
               << std::endl;
 }
 
@@ -216,21 +188,26 @@
     argc -= optind;
     argv += optind;
 
-    if (argc != 1) {
+    if (argc != 1 || interface_inheritance_hierarchy_file.empty()) {
         PrintUsage();
         return EXIT_FAILURE;
     }
 
+    auto interface_inheritance_hierarchy_map =
+            ReadInterfaceInheritanceHierarchy(interface_inheritance_hierarchy_file);
+    if (!interface_inheritance_hierarchy_map) {
+        LOG(ERROR) << interface_inheritance_hierarchy_map.error();
+        return EXIT_FAILURE;
+    }
+    SetKnownInterfaces(*interface_inheritance_hierarchy_map);
+
     const BuiltinFunctionMap& function_map = GetBuiltinFunctionMap();
     Action::set_function_map(&function_map);
     ActionManager& am = ActionManager::GetInstance();
     ServiceList& sl = ServiceList::GetInstance();
     Parser parser;
-    parser.AddSectionParser(
-            "service",
-            std::make_unique<ServiceParser>(
-                    &sl, nullptr,
-                    ReadInterfaceInheritanceHierarchy(interface_inheritance_hierarchy_file)));
+    parser.AddSectionParser("service", std::make_unique<ServiceParser>(
+                                               &sl, nullptr, *interface_inheritance_hierarchy_map));
     parser.AddSectionParser("on", std::make_unique<ActionParser>(&am, nullptr));
     parser.AddSectionParser("import", std::make_unique<HostImportParser>());
 
@@ -238,9 +215,10 @@
         LOG(ERROR) << "Failed to open init rc script '" << *argv << "'";
         return EXIT_FAILURE;
     }
-    if (parser.parse_error_count() > 0) {
-        LOG(ERROR) << "Failed to parse init script '" << *argv << "' with "
-                   << parser.parse_error_count() << " errors";
+    size_t failures = parser.parse_error_count() + am.CheckAllCommands() + sl.CheckAllCommands();
+    if (failures > 0) {
+        LOG(ERROR) << "Failed to parse init script '" << *argv << "' with " << failures
+                   << " errors";
         return EXIT_FAILURE;
     }
     return EXIT_SUCCESS;
diff --git a/init/import_parser.cpp b/init/import_parser.cpp
index c72b7d6..1a43508 100644
--- a/init/import_parser.cpp
+++ b/init/import_parser.cpp
@@ -29,15 +29,14 @@
         return Error() << "single argument needed for import\n";
     }
 
-    std::string conf_file;
-    bool ret = expand_props(args[1], &conf_file);
-    if (!ret) {
-        return Error() << "error while expanding import";
+    auto conf_file = ExpandProps(args[1]);
+    if (!conf_file) {
+        return Error() << "Could not expand import: " << conf_file.error();
     }
 
-    LOG(INFO) << "Added '" << conf_file << "' to import list";
+    LOG(INFO) << "Added '" << *conf_file << "' to import list";
     if (filename_.empty()) filename_ = filename;
-    imports_.emplace_back(std::move(conf_file), line);
+    imports_.emplace_back(std::move(*conf_file), line);
     return {};
 }
 
diff --git a/init/interface_utils.cpp b/init/interface_utils.cpp
new file mode 100644
index 0000000..a54860f
--- /dev/null
+++ b/init/interface_utils.cpp
@@ -0,0 +1,149 @@
+/*
+ * 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 "interface_utils.h"
+
+#include <fstream>
+#include <sstream>
+
+#include <android-base/strings.h>
+#include <hidl-util/FqInstance.h>
+#include <json/json.h>
+
+using android::FqInstance;
+using android::FQName;
+using android::base::Error;
+
+namespace android {
+namespace init {
+
+namespace {
+
+std::string FQNamesToString(const std::set<FQName>& fqnames) {
+    std::set<std::string> fqname_strings;
+    for (const FQName& fqname : fqnames) {
+        fqname_strings.insert(fqname.string());
+    }
+    return android::base::Join(fqname_strings, " ");
+}
+
+}  // namespace
+
+Result<InterfaceInheritanceHierarchyMap> ReadInterfaceInheritanceHierarchy(
+        const std::string& path) {
+    Json::Value root;
+    Json::Reader reader;
+    std::ifstream stream(path);
+    if (!reader.parse(stream, root)) {
+        return Error() << "Failed to read interface inheritance hierarchy file: " << path << "\n"
+                       << reader.getFormattedErrorMessages();
+    }
+
+    InterfaceInheritanceHierarchyMap result;
+    for (const Json::Value& entry : root) {
+        std::set<FQName> inherited_interfaces;
+        for (const Json::Value& intf : entry["inheritedInterfaces"]) {
+            FQName fqname;
+            if (!fqname.setTo(intf.asString())) {
+                return Error() << "Unable to parse interface '" << intf.asString() << "'";
+            }
+            inherited_interfaces.insert(fqname);
+        }
+        std::string intf_string = entry["interface"].asString();
+        FQName fqname;
+        if (!fqname.setTo(intf_string)) {
+            return Error() << "Unable to parse interface '" << intf_string << "'";
+        }
+        result[fqname] = inherited_interfaces;
+    }
+
+    return result;
+}
+
+Result<void> CheckInterfaceInheritanceHierarchy(const std::set<std::string>& instances,
+                                                const InterfaceInheritanceHierarchyMap& hierarchy) {
+    std::set<FQName> interface_fqnames;
+    for (const std::string& instance : instances) {
+        FqInstance fqinstance;
+        if (!fqinstance.setTo(instance)) {
+            return Error() << "Unable to parse interface instance '" << instance << "'";
+        }
+        interface_fqnames.insert(fqinstance.getFqName());
+    }
+    return CheckInterfaceInheritanceHierarchy(interface_fqnames, hierarchy);
+}
+
+Result<void> CheckInterfaceInheritanceHierarchy(const std::set<FQName>& interfaces,
+                                                const InterfaceInheritanceHierarchyMap& hierarchy) {
+    std::ostringstream error_stream;
+    for (const FQName& intf : interfaces) {
+        if (hierarchy.count(intf) == 0) {
+            error_stream << "\nInterface is not in the known set of hidl_interfaces: '"
+                         << intf.string()
+                         << "'. Please ensure the interface is spelled correctly and built "
+                         << "by a hidl_interface target.";
+            continue;
+        }
+        const std::set<FQName>& required_interfaces = hierarchy.at(intf);
+        std::set<FQName> diff;
+        std::set_difference(required_interfaces.begin(), required_interfaces.end(),
+                            interfaces.begin(), interfaces.end(),
+                            std::inserter(diff, diff.begin()));
+        if (!diff.empty()) {
+            error_stream << "\nInterface '" << intf.string() << "' requires its full inheritance "
+                         << "hierarchy to be listed in this init_rc file. Missing "
+                         << "interfaces: [" << FQNamesToString(diff) << "]";
+        }
+    }
+    const std::string& errors = error_stream.str();
+    if (!errors.empty()) {
+        return Error() << errors;
+    }
+
+    return {};
+}
+
+std::optional<std::set<FQName>> known_interfaces;
+
+void SetKnownInterfaces(const InterfaceInheritanceHierarchyMap& hierarchy) {
+    known_interfaces = std::set<FQName>();
+    for (const auto& [intf, inherited_interfaces] : hierarchy) {
+        known_interfaces->insert(intf);
+    }
+}
+
+Result<void> IsKnownInterface(const std::string& instance) {
+    FqInstance fqinstance;
+    if (!fqinstance.setTo(instance)) {
+        return Error() << "Unable to parse interface instance '" << instance << "'";
+    }
+    return IsKnownInterface(fqinstance.getFqName());
+}
+
+Result<void> IsKnownInterface(const FQName& intf) {
+    if (!known_interfaces) {
+        return Error() << "No known interfaces have been loaded.";
+    }
+    if (known_interfaces->count(intf) == 0) {
+        return Error() << "Interface is not in the known set of hidl_interfaces: '" << intf.string()
+                       << "'. Please ensure the interface is spelled correctly and built "
+                       << "by a hidl_interface target.";
+    }
+    return {};
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/interface_utils.h b/init/interface_utils.h
new file mode 100644
index 0000000..bd0c104
--- /dev/null
+++ b/init/interface_utils.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <map>
+#include <set>
+#include <string>
+
+#include <hidl-util/FQName.h>
+
+#include "result.h"
+
+namespace android {
+namespace init {
+
+using InterfaceInheritanceHierarchyMap = std::map<android::FQName, std::set<android::FQName>>;
+
+// Reads the HIDL interface inheritance hierarchy JSON file at the given path.
+Result<InterfaceInheritanceHierarchyMap> ReadInterfaceInheritanceHierarchy(const std::string& path);
+
+// For the given set of interfaces / interface instances, checks that each
+// interface's hierarchy of inherited interfaces is also included in the given
+// interface set. Uses the provided hierarchy data.
+Result<void> CheckInterfaceInheritanceHierarchy(const std::set<std::string>& instances,
+                                                const InterfaceInheritanceHierarchyMap& hierarchy);
+Result<void> CheckInterfaceInheritanceHierarchy(const std::set<android::FQName>& interfaces,
+                                                const InterfaceInheritanceHierarchyMap& hierarchy);
+
+// Saves the set of known interfaces using the provided HIDL interface
+// inheritance hierarchy.
+void SetKnownInterfaces(const InterfaceInheritanceHierarchyMap& hierarchy);
+
+// Checks if the provided interface is in the set of known interfaces. Returns
+// an empty Result if present, otherwise an Error.
+Result<void> IsKnownInterface(const std::string& instance);
+Result<void> IsKnownInterface(const FQName& intf);
+
+}  // namespace init
+}  // namespace android
diff --git a/init/property_service.cpp b/init/property_service.cpp
index 3761750..17622a3 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -174,13 +174,8 @@
         return PROP_ERROR_INVALID_NAME;
     }
 
-    if (valuelen >= PROP_VALUE_MAX && !StartsWith(name, "ro.")) {
-        *error = "Property value too long";
-        return PROP_ERROR_INVALID_VALUE;
-    }
-
-    if (mbstowcs(nullptr, value.data(), 0) == static_cast<std::size_t>(-1)) {
-        *error = "Value is not a UTF8 encoded string";
+    if (auto result = IsLegalPropertyValue(name, value); !result) {
+        *error = result.error().message();
         return PROP_ERROR_INVALID_VALUE;
     }
 
@@ -648,13 +643,14 @@
             }
 
             std::string raw_filename(fn);
-            std::string expanded_filename;
-            if (!expand_props(raw_filename, &expanded_filename)) {
-                LOG(ERROR) << "Could not expand filename '" << raw_filename << "'";
+            auto expanded_filename = ExpandProps(raw_filename);
+
+            if (!expanded_filename) {
+                LOG(ERROR) << "Could not expand filename ': " << expanded_filename.error();
                 continue;
             }
 
-            load_properties_from_file(expanded_filename.c_str(), key, properties);
+            load_properties_from_file(expanded_filename->c_str(), key, properties);
         } else {
             value = strchr(key, '=');
             if (!value) continue;
diff --git a/init/selinux.cpp b/init/selinux.cpp
index 54be086..143cdfd 100644
--- a/init/selinux.cpp
+++ b/init/selinux.cpp
@@ -497,24 +497,28 @@
 // This function returns the Android version with which the vendor SEPolicy was compiled.
 // It is used for version checks such as whether or not vendor_init should be used
 int SelinuxGetVendorAndroidVersion() {
-    if (!IsSplitPolicyDevice()) {
-        // If this device does not split sepolicy files, it's not a Treble device and therefore,
-        // we assume it's always on the latest platform.
-        return __ANDROID_API_FUTURE__;
-    }
+    static int vendor_android_version = [] {
+        if (!IsSplitPolicyDevice()) {
+            // If this device does not split sepolicy files, it's not a Treble device and therefore,
+            // we assume it's always on the latest platform.
+            return __ANDROID_API_FUTURE__;
+        }
 
-    std::string version;
-    if (!GetVendorMappingVersion(&version)) {
-        LOG(FATAL) << "Could not read vendor SELinux version";
-    }
+        std::string version;
+        if (!GetVendorMappingVersion(&version)) {
+            LOG(FATAL) << "Could not read vendor SELinux version";
+        }
 
-    int major_version;
-    std::string major_version_str(version, 0, version.find('.'));
-    if (!ParseInt(major_version_str, &major_version)) {
-        PLOG(FATAL) << "Failed to parse the vendor sepolicy major version " << major_version_str;
-    }
+        int major_version;
+        std::string major_version_str(version, 0, version.find('.'));
+        if (!ParseInt(major_version_str, &major_version)) {
+            PLOG(FATAL) << "Failed to parse the vendor sepolicy major version "
+                        << major_version_str;
+        }
 
-    return major_version;
+        return major_version;
+    }();
+    return vendor_android_version;
 }
 
 // This function initializes SELinux then execs init to run in the init SELinux context.
diff --git a/init/service.cpp b/init/service.cpp
index 47f4db9..9537843 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -100,9 +100,11 @@
     expanded_args.resize(args.size());
     c_strings.push_back(const_cast<char*>(args[0].data()));
     for (std::size_t i = 1; i < args.size(); ++i) {
-        if (!expand_props(args[i], &expanded_args[i])) {
-            LOG(FATAL) << args[0] << ": cannot expand '" << args[i] << "'";
+        auto expanded_arg = ExpandProps(args[i]);
+        if (!expanded_arg) {
+            LOG(FATAL) << args[0] << ": cannot expand arguments': " << expanded_arg.error();
         }
+        expanded_args[i] = *expanded_arg;
         c_strings.push_back(expanded_args[i].data());
     }
     c_strings.push_back(nullptr);
@@ -165,6 +167,15 @@
             property_set(boottime_property, std::to_string(start_ns));
         }
     }
+
+    // init.svc_debug_pid.* properties are only for tests, and should not be used
+    // on device for security checks.
+    std::string pid_property = "init.svc_debug_pid." + name_;
+    if (new_state == "running") {
+        property_set(pid_property, std::to_string(pid_));
+    } else if (new_state == "stopped") {
+        property_set(pid_property, "");
+    }
 }
 
 void Service::KillProcessGroup(int signal) {
@@ -633,7 +644,8 @@
     }
 }
 
-std::unique_ptr<Service> Service::MakeTemporaryOneshotService(const std::vector<std::string>& args) {
+Result<std::unique_ptr<Service>> Service::MakeTemporaryOneshotService(
+        const std::vector<std::string>& args) {
     // Parse the arguments: exec [SECLABEL [UID [GID]*] --] COMMAND ARGS...
     // SECLABEL can be a - to denote default
     std::size_t command_arg = 1;
@@ -644,13 +656,11 @@
         }
     }
     if (command_arg > 4 + NR_SVC_SUPP_GIDS) {
-        LOG(ERROR) << "exec called with too many supplementary group ids";
-        return nullptr;
+        return Error() << "exec called with too many supplementary group ids";
     }
 
     if (command_arg >= args.size()) {
-        LOG(ERROR) << "exec called without command";
-        return nullptr;
+        return Error() << "exec called without command";
     }
     std::vector<std::string> str_args(args.begin() + command_arg, args.end());
 
@@ -669,8 +679,7 @@
     if (command_arg > 3) {
         uid = DecodeUid(args[2]);
         if (!uid) {
-            LOG(ERROR) << "Unable to decode UID for '" << args[2] << "': " << uid.error();
-            return nullptr;
+            return Error() << "Unable to decode UID for '" << args[2] << "': " << uid.error();
         }
     }
     Result<gid_t> gid = 0;
@@ -678,16 +687,14 @@
     if (command_arg > 4) {
         gid = DecodeUid(args[3]);
         if (!gid) {
-            LOG(ERROR) << "Unable to decode GID for '" << args[3] << "': " << gid.error();
-            return nullptr;
+            return Error() << "Unable to decode GID for '" << args[3] << "': " << gid.error();
         }
         std::size_t nr_supp_gids = command_arg - 1 /* -- */ - 4 /* exec SECLABEL UID GID */;
         for (size_t i = 0; i < nr_supp_gids; ++i) {
             auto supp_gid = DecodeUid(args[4 + i]);
             if (!supp_gid) {
-                LOG(ERROR) << "Unable to decode GID for '" << args[4 + i]
-                           << "': " << supp_gid.error();
-                return nullptr;
+                return Error() << "Unable to decode GID for '" << args[4 + i]
+                               << "': " << supp_gid.error();
             }
             supp_gids.push_back(*supp_gid);
         }
diff --git a/init/service.h b/init/service.h
index cdf31bb..ccefc8e 100644
--- a/init/service.h
+++ b/init/service.h
@@ -71,7 +71,8 @@
             const std::vector<gid_t>& supp_gids, int namespace_flags, const std::string& seclabel,
             Subcontext* subcontext_for_restart_commands, const std::vector<std::string>& args);
 
-    static std::unique_ptr<Service> MakeTemporaryOneshotService(const std::vector<std::string>& args);
+    static Result<std::unique_ptr<Service>> MakeTemporaryOneshotService(
+            const std::vector<std::string>& args);
 
     bool IsRunning() { return (flags_ & SVC_RUNNING) != 0; }
     Result<void> ExecStart();
@@ -96,6 +97,7 @@
     void AddReapCallback(std::function<void(const siginfo_t& siginfo)> callback) {
         reap_callbacks_.emplace_back(std::move(callback));
     }
+    size_t CheckAllCommands() const { return onrestart_.CheckAllCommands(); }
 
     static bool is_exec_service_running() { return is_exec_service_running_; }
 
diff --git a/init/service_list.cpp b/init/service_list.cpp
index 3a48183..c51a9cf 100644
--- a/init/service_list.cpp
+++ b/init/service_list.cpp
@@ -28,6 +28,14 @@
     return instance;
 }
 
+size_t ServiceList::CheckAllCommands() {
+    size_t failures = 0;
+    for (const auto& service : services_) {
+        failures += service->CheckAllCommands();
+    }
+    return failures;
+}
+
 void ServiceList::AddService(std::unique_ptr<Service> service) {
     services_.emplace_back(std::move(service));
 }
diff --git a/init/service_list.h b/init/service_list.h
index 2136a21..ee2c702 100644
--- a/init/service_list.h
+++ b/init/service_list.h
@@ -30,6 +30,7 @@
 
     // Exposed for testing
     ServiceList();
+    size_t CheckAllCommands();
 
     void AddService(std::unique_ptr<Service> service);
     void RemoveService(const Service& svc);
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index 65d96c6..dd552fb 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -193,9 +193,9 @@
 Result<void> ServiceParser::ParseKeycodes(std::vector<std::string>&& args) {
     auto it = args.begin() + 1;
     if (args.size() == 2 && StartsWith(args[1], "$")) {
-        std::string expanded;
-        if (!expand_props(args[1], &expanded)) {
-            return Error() << "Could not expand property '" << args[1] << "'";
+        auto expanded = ExpandProps(args[1]);
+        if (!expanded) {
+            return expanded.error();
         }
 
         // If the property is not set, it defaults to none, in which case there are no keycodes
@@ -204,7 +204,7 @@
             return {};
         }
 
-        args = Split(expanded, ",");
+        args = Split(*expanded, ",");
         it = args.begin();
     }
 
@@ -422,9 +422,11 @@
     FileDescriptor file;
     file.type = args[2];
 
-    if (!expand_props(args[1], &file.name)) {
-        return Error() << "Could not expand property in file path '" << args[1] << "'";
+    auto file_name = ExpandProps(args[1]);
+    if (!file_name) {
+        return Error() << "Could not expand file path ': " << file_name.error();
     }
+    file.name = *file_name;
     if (file.name[0] != '/' || file.name.find("../") != std::string::npos) {
         return Error() << "file name must not be relative";
     }
@@ -566,33 +568,10 @@
     }
 
     if (interface_inheritance_hierarchy_) {
-        std::set<std::string> interface_names;
-        for (const std::string& intf : service_->interfaces()) {
-            interface_names.insert(Split(intf, "/")[0]);
-        }
-        std::ostringstream error_stream;
-        for (const std::string& intf : interface_names) {
-            if (interface_inheritance_hierarchy_->count(intf) == 0) {
-                error_stream << "\nInterface is not in the known set of hidl_interfaces: '" << intf
-                             << "'. Please ensure the interface is spelled correctly and built "
-                             << "by a hidl_interface target.";
-                continue;
-            }
-            const std::set<std::string>& required_interfaces =
-                    (*interface_inheritance_hierarchy_)[intf];
-            std::set<std::string> diff;
-            std::set_difference(required_interfaces.begin(), required_interfaces.end(),
-                                interface_names.begin(), interface_names.end(),
-                                std::inserter(diff, diff.begin()));
-            if (!diff.empty()) {
-                error_stream << "\nInterface '" << intf << "' requires its full inheritance "
-                             << "hierarchy to be listed in this init_rc file. Missing "
-                             << "interfaces: [" << base::Join(diff, " ") << "]";
-            }
-        }
-        const std::string& errors = error_stream.str();
-        if (!errors.empty()) {
-            return Error() << errors;
+        if (const auto& check_hierarchy_result = CheckInterfaceInheritanceHierarchy(
+                    service_->interfaces(), *interface_inheritance_hierarchy_);
+            !check_hierarchy_result) {
+            return Error() << check_hierarchy_result.error();
         }
     }
 
diff --git a/init/service_parser.h b/init/service_parser.h
index 98ab15a..4729874 100644
--- a/init/service_parser.h
+++ b/init/service_parser.h
@@ -18,6 +18,7 @@
 
 #include <vector>
 
+#include "interface_utils.h"
 #include "parser.h"
 #include "service.h"
 #include "service_list.h"
@@ -26,8 +27,6 @@
 namespace android {
 namespace init {
 
-using InterfaceInheritanceHierarchyMap = std::map<std::string, std::set<std::string>>;
-
 class ServiceParser : public SectionParser {
   public:
     ServiceParser(
diff --git a/init/service_test.cpp b/init/service_test.cpp
index 6a34acc..c9cc7bd 100644
--- a/init/service_test.cpp
+++ b/init/service_test.cpp
@@ -75,15 +75,15 @@
 TEST(service, make_temporary_oneshot_service_invalid_syntax) {
     std::vector<std::string> args;
     // Nothing.
-    ASSERT_EQ(nullptr, Service::MakeTemporaryOneshotService(args));
+    ASSERT_FALSE(Service::MakeTemporaryOneshotService(args));
 
     // No arguments to 'exec'.
     args.push_back("exec");
-    ASSERT_EQ(nullptr, Service::MakeTemporaryOneshotService(args));
+    ASSERT_FALSE(Service::MakeTemporaryOneshotService(args));
 
     // No command in "exec --".
     args.push_back("--");
-    ASSERT_EQ(nullptr, Service::MakeTemporaryOneshotService(args));
+    ASSERT_FALSE(Service::MakeTemporaryOneshotService(args));
 }
 
 TEST(service, make_temporary_oneshot_service_too_many_supplementary_gids) {
@@ -97,7 +97,7 @@
     }
     args.push_back("--");
     args.push_back("/system/bin/id");
-    ASSERT_EQ(nullptr, Service::MakeTemporaryOneshotService(args));
+    ASSERT_FALSE(Service::MakeTemporaryOneshotService(args));
 }
 
 static void Test_make_temporary_oneshot_service(bool dash_dash, bool seclabel, bool uid, bool gid,
@@ -122,8 +122,9 @@
     }
     args.push_back("/system/bin/toybox");
     args.push_back("id");
-    auto svc = Service::MakeTemporaryOneshotService(args);
-    ASSERT_NE(nullptr, svc);
+    auto service_ret = Service::MakeTemporaryOneshotService(args);
+    ASSERT_TRUE(service_ret);
+    auto svc = std::move(*service_ret);
 
     if (seclabel) {
         ASSERT_EQ("u:r:su:s0", svc->seclabel());
diff --git a/init/subcontext.cpp b/init/subcontext.cpp
index a13f0c7..00f91d8 100644
--- a/init/subcontext.cpp
+++ b/init/subcontext.cpp
@@ -151,15 +151,15 @@
 void SubcontextProcess::ExpandArgs(const SubcontextCommand::ExpandArgsCommand& expand_args_command,
                                    SubcontextReply* reply) const {
     for (const auto& arg : expand_args_command.args()) {
-        auto expanded_prop = std::string{};
-        if (!expand_props(arg, &expanded_prop)) {
+        auto expanded_arg = ExpandProps(arg);
+        if (!expanded_arg) {
             auto* failure = reply->mutable_failure();
-            failure->set_error_string("Failed to expand '" + arg + "'");
+            failure->set_error_string(expanded_arg.error().message());
             failure->set_error_errno(0);
             return;
         } else {
             auto* expand_args_reply = reply->mutable_expand_args_reply();
-            expand_args_reply->add_expanded_args(expanded_prop);
+            expand_args_reply->add_expanded_args(*expanded_arg);
         }
     }
 }
diff --git a/init/subcontext_test.cpp b/init/subcontext_test.cpp
index e120a62..ae89c38 100644
--- a/init/subcontext_test.cpp
+++ b/init/subcontext_test.cpp
@@ -166,7 +166,8 @@
         };
         auto result = subcontext.ExpandArgs(args);
         ASSERT_FALSE(result);
-        EXPECT_EQ("Failed to expand '" + args[1] + "'", result.error().message());
+        EXPECT_EQ("unexpected end of string in '" + args[1] + "', looking for }",
+                  result.error().message());
     });
 }
 
diff --git a/init/test_utils/Android.bp b/init/test_utils/Android.bp
new file mode 100644
index 0000000..1cb05b6
--- /dev/null
+++ b/init/test_utils/Android.bp
@@ -0,0 +1,27 @@
+cc_library_static {
+    name: "libinit_test_utils",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Wno-unused-parameter",
+        "-Werror",
+    ],
+    srcs: [
+        "service_utils.cpp",
+    ],
+    shared_libs: [
+        "libcutils",
+        "liblog",
+        "libjsoncpp",
+        "libprotobuf-cpp-lite",
+        "libhidl-gen-utils",
+    ],
+    whole_static_libs: [
+        "libinit",
+        "libpropertyinfoparser",
+    ],
+    static_libs: [
+        "libbase",
+    ],
+    export_include_dirs: ["include"], // for tests
+}
diff --git a/init/test_utils/include/init-test-utils/service_utils.h b/init/test_utils/include/init-test-utils/service_utils.h
new file mode 100644
index 0000000..3ec61d4
--- /dev/null
+++ b/init/test_utils/include/init-test-utils/service_utils.h
@@ -0,0 +1,32 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#pragma once
+
+#include <map>
+#include <set>
+
+#include <android-base/result.h>
+#include <hidl-util/FqInstance.h>
+
+namespace android {
+namespace init {
+
+using ServiceInterfacesMap = std::map<std::string, std::set<android::FqInstance>>;
+android::base::Result<ServiceInterfacesMap> GetOnDeviceServiceInterfacesMap();
+
+}  // namespace init
+}  // namespace android
diff --git a/init/test_utils/service_utils.cpp b/init/test_utils/service_utils.cpp
new file mode 100644
index 0000000..bc00702
--- /dev/null
+++ b/init/test_utils/service_utils.cpp
@@ -0,0 +1,63 @@
+//
+// 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 <string>
+
+#include <android-base/logging.h>
+
+#include "../parser.h"
+#include "../service.h"
+#include "../service_list.h"
+#include "../service_parser.h"
+#include "include/init-test-utils/service_utils.h"
+
+namespace android {
+namespace init {
+
+android::base::Result<ServiceInterfacesMap> GetOnDeviceServiceInterfacesMap() {
+    ServiceList& service_list = ServiceList::GetInstance();
+    Parser parser;
+    parser.AddSectionParser("service",
+                            std::make_unique<ServiceParser>(&service_list, nullptr, std::nullopt));
+    for (const auto& location : {
+                 "/init.rc",
+                 "/system/etc/init",
+                 "/system_ext/etc/init",
+                 "/product/etc/init",
+                 "/odm/etc/init",
+                 "/vendor/etc/init",
+         }) {
+        parser.ParseConfig(location);
+    }
+
+    ServiceInterfacesMap result;
+    for (const auto& service : service_list.services()) {
+        // Create an entry for all services, including services that may not
+        // have any declared interfaces.
+        result[service->name()] = std::set<android::FqInstance>();
+        for (const auto& intf : service->interfaces()) {
+            android::FqInstance fqInstance;
+            if (!fqInstance.setTo(intf)) {
+                return android::base::Error() << "Unable to parse interface: '" << intf << "'";
+            }
+            result[service->name()].insert(fqInstance);
+        }
+    }
+    return result;
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/util.cpp b/init/util.cpp
index 8bfb755..0532375 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -41,13 +41,18 @@
 #include <selinux/android.h>
 
 #if defined(__ANDROID__)
+#include <android/api-level.h>
+#include <sys/system_properties.h>
+
 #include "reboot_utils.h"
 #include "selabel.h"
+#include "selinux.h"
 #else
 #include "host_init_stubs.h"
 #endif
 
 using android::base::boot_clock;
+using android::base::StartsWith;
 using namespace std::literals::string_literals;
 
 namespace android {
@@ -267,12 +272,10 @@
     return S_ISDIR(info.st_mode);
 }
 
-bool expand_props(const std::string& src, std::string* dst) {
+Result<std::string> ExpandProps(const std::string& src) {
     const char* src_ptr = src.c_str();
 
-    if (!dst) {
-        return false;
-    }
+    std::string dst;
 
     /* - variables can either be $x.y or ${x.y}, in case they are only part
      *   of the string.
@@ -286,19 +289,19 @@
 
         c = strchr(src_ptr, '$');
         if (!c) {
-            dst->append(src_ptr);
-            return true;
+            dst.append(src_ptr);
+            return dst;
         }
 
-        dst->append(src_ptr, c);
+        dst.append(src_ptr, c);
         c++;
 
         if (*c == '$') {
-            dst->push_back(*(c++));
+            dst.push_back(*(c++));
             src_ptr = c;
             continue;
         } else if (*c == '\0') {
-            return true;
+            return dst;
         }
 
         std::string prop_name;
@@ -308,8 +311,7 @@
             const char* end = strchr(c, '}');
             if (!end) {
                 // failed to find closing brace, abort.
-                LOG(ERROR) << "unexpected end of string in '" << src << "', looking for }";
-                return false;
+                return Error() << "unexpected end of string in '" << src << "', looking for }";
             }
             prop_name = std::string(c, end);
             c = end + 1;
@@ -320,29 +322,34 @@
             }
         } else {
             prop_name = c;
-            LOG(ERROR) << "using deprecated syntax for specifying property '" << c << "', use ${name} instead";
+            if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_R__) {
+                return Error() << "using deprecated syntax for specifying property '" << c
+                               << "', use ${name} instead";
+            } else {
+                LOG(ERROR) << "using deprecated syntax for specifying property '" << c
+                           << "', use ${name} instead";
+            }
             c += prop_name.size();
         }
 
         if (prop_name.empty()) {
-            LOG(ERROR) << "invalid zero-length property name in '" << src << "'";
-            return false;
+            return Error() << "invalid zero-length property name in '" << src << "'";
         }
 
         std::string prop_val = android::base::GetProperty(prop_name, "");
         if (prop_val.empty()) {
             if (def_val.empty()) {
-                LOG(ERROR) << "property '" << prop_name << "' doesn't exist while expanding '" << src << "'";
-                return false;
+                return Error() << "property '" << prop_name << "' doesn't exist while expanding '"
+                               << src << "'";
             }
             prop_val = def_val;
         }
 
-        dst->append(prop_val);
+        dst.append(prop_val);
         src_ptr = c;
     }
 
-    return true;
+    return dst;
 }
 
 static std::string init_android_dt_dir() {
@@ -414,6 +421,58 @@
     return true;
 }
 
+Result<void> IsLegalPropertyValue(const std::string& name, const std::string& value) {
+    if (value.size() >= PROP_VALUE_MAX && !StartsWith(name, "ro.")) {
+        return Error() << "Property value too long";
+    }
+
+    if (mbstowcs(nullptr, value.data(), 0) == static_cast<std::size_t>(-1)) {
+        return Error() << "Value is not a UTF8 encoded string";
+    }
+
+    return {};
+}
+
+Result<std::pair<int, std::vector<std::string>>> ParseRestorecon(
+        const std::vector<std::string>& args) {
+    struct flag_type {
+        const char* name;
+        int value;
+    };
+    static const flag_type flags[] = {
+            {"--recursive", SELINUX_ANDROID_RESTORECON_RECURSE},
+            {"--skip-ce", SELINUX_ANDROID_RESTORECON_SKIPCE},
+            {"--cross-filesystems", SELINUX_ANDROID_RESTORECON_CROSS_FILESYSTEMS},
+            {0, 0}};
+
+    int flag = 0;
+    std::vector<std::string> paths;
+
+    bool in_flags = true;
+    for (size_t i = 1; i < args.size(); ++i) {
+        if (android::base::StartsWith(args[i], "--")) {
+            if (!in_flags) {
+                return Error() << "flags must precede paths";
+            }
+            bool found = false;
+            for (size_t j = 0; flags[j].name; ++j) {
+                if (args[i] == flags[j].name) {
+                    flag |= flags[j].value;
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                return Error() << "bad flag " << args[i];
+            }
+        } else {
+            in_flags = false;
+            paths.emplace_back(args[i]);
+        }
+    }
+    return std::pair(flag, paths);
+}
+
 static void InitAborter(const char* abort_message) {
     // When init forks, it continues to use this aborter for LOG(FATAL), but we want children to
     // simply abort instead of trying to reboot the system.
diff --git a/init/util.h b/init/util.h
index 6a12fb6..4cccefe 100644
--- a/init/util.h
+++ b/init/util.h
@@ -14,24 +14,20 @@
  * limitations under the License.
  */
 
-#ifndef _INIT_UTIL_H_
-#define _INIT_UTIL_H_
+#pragma once
 
 #include <sys/stat.h>
 #include <sys/types.h>
 
 #include <chrono>
 #include <functional>
-#include <ostream>
 #include <string>
 
 #include <android-base/chrono_utils.h>
-#include <selinux/label.h>
 
 #include "result.h"
 
 using android::base::boot_clock;
-using namespace std::chrono_literals;
 
 namespace android {
 namespace init {
@@ -52,7 +48,7 @@
                            const std::function<void(const std::string&, const std::string&, bool)>&);
 bool make_dir(const std::string& path, mode_t mode);
 bool is_dir(const char* pathname);
-bool expand_props(const std::string& src, std::string* dst);
+Result<std::string> ExpandProps(const std::string& src);
 
 // Returns the platform's Android DT directory as specified in the kernel cmdline.
 // If the platform does not configure a custom DT path, returns the standard one (based in procfs).
@@ -62,11 +58,13 @@
 bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content);
 
 bool IsLegalPropertyName(const std::string& name);
+Result<void> IsLegalPropertyValue(const std::string& name, const std::string& value);
+
+Result<std::pair<int, std::vector<std::string>>> ParseRestorecon(
+        const std::vector<std::string>& args);
 
 void SetStdioToDevNull(char** argv);
 void InitKernelLogging(char** argv);
 bool IsRecoveryMode();
 }  // namespace init
 }  // namespace android
-
-#endif
diff --git a/libcutils/Android.bp b/libcutils/Android.bp
index 319a73a..5144fc6 100644
--- a/libcutils/Android.bp
+++ b/libcutils/Android.bp
@@ -68,7 +68,6 @@
         "record_stream.cpp",
         "sockets.cpp",
         "strdup16to8.cpp",
-        "strdup8to16.cpp",
         "strlcpy.c",
         "threads.cpp",
     ],
diff --git a/libcutils/include/cutils/jstring.h b/libcutils/include/cutils/jstring.h
index a342608..6ede786 100644
--- a/libcutils/include/cutils/jstring.h
+++ b/libcutils/include/cutils/jstring.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef __CUTILS_STRING16_H
-#define __CUTILS_STRING16_H
+#pragma once
 
 #include <stdint.h>
 #include <stddef.h>
@@ -33,14 +32,6 @@
 extern size_t strnlen16to8 (const char16_t* s, size_t n);
 extern char * strncpy16to8 (char *dest, const char16_t*s, size_t n);
 
-extern char16_t * strdup8to16 (const char* s, size_t *out_len);
-extern size_t strlen8to16 (const char* utf8Str);
-extern char16_t * strcpy8to16 (char16_t *dest, const char*s, size_t *out_len);
-extern char16_t * strcpylen8to16 (char16_t *dest, const char*s, int length,
-    size_t *out_len);
-
 #ifdef __cplusplus
 }
 #endif
-
-#endif /* __CUTILS_STRING16_H */
diff --git a/libcutils/strdup8to16.cpp b/libcutils/strdup8to16.cpp
deleted file mode 100644
index d1e51b9..0000000
--- a/libcutils/strdup8to16.cpp
+++ /dev/null
@@ -1,215 +0,0 @@
-/* libs/cutils/strdup8to16.c
-**
-** Copyright 2006, 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 <cutils/jstring.h>
-
-#include <assert.h>
-#include <limits.h>
-#include <stdlib.h>
-
-/* See http://www.unicode.org/reports/tr22/ for discussion
- * on invalid sequences
- */
-
-#define UTF16_REPLACEMENT_CHAR 0xfffd
-
-/* Clever trick from Dianne that returns 1-4 depending on leading bit sequence*/
-#define UTF8_SEQ_LENGTH(ch) (((0xe5000000 >> (((ch) >> 3) & 0x1e)) & 3) + 1)
-
-/* note: macro expands to multiple lines */
-#define UTF8_SHIFT_AND_MASK(unicode, byte)  \
-            (unicode)<<=6; (unicode) |= (0x3f & (byte));
-
-#define UNICODE_UPPER_LIMIT 0x10fffd    
-
-/**
- * out_len is an out parameter (which may not be null) containing the
- * length of the UTF-16 string (which may contain embedded \0's)
- */
-
-extern char16_t * strdup8to16 (const char* s, size_t *out_len)
-{
-    char16_t *ret;
-    size_t len;
-
-    if (s == NULL) return NULL;
-
-    len = strlen8to16(s);
-
-    // fail on overflow
-    if (len && SIZE_MAX/len < sizeof(char16_t))
-        return NULL;
-
-    // no plus-one here. UTF-16 strings are not null terminated
-    ret = (char16_t *) malloc (sizeof(char16_t) * len);
-
-    return strcpy8to16 (ret, s, out_len);
-}
-
-/**
- * Like "strlen", but for strings encoded with Java's modified UTF-8.
- *
- * The value returned is the number of UTF-16 characters required
- * to represent this string.
- */
-extern size_t strlen8to16 (const char* utf8Str)
-{
-    size_t len = 0;
-    int ic;
-    int expected = 0;
-
-    while ((ic = *utf8Str++) != '\0') {
-        /* bytes that start 0? or 11 are lead bytes and count as characters.*/
-        /* bytes that start 10 are extention bytes and are not counted */
-         
-        if ((ic & 0xc0) == 0x80) {
-            /* count the 0x80 extention bytes. if we have more than
-             * expected, then start counting them because strcpy8to16
-             * will insert UTF16_REPLACEMENT_CHAR's
-             */
-            expected--;
-            if (expected < 0) {
-                len++;
-            }
-        } else {
-            len++;
-            expected = UTF8_SEQ_LENGTH(ic) - 1;
-
-            /* this will result in a surrogate pair */
-            if (expected == 3) {
-                len++;
-            }
-        }
-    }
-
-    return len;
-}
-
-
-
-/*
- * Retrieve the next UTF-32 character from a UTF-8 string.
- *
- * Stops at inner \0's
- *
- * Returns UTF16_REPLACEMENT_CHAR if an invalid sequence is encountered
- *
- * Advances "*pUtf8Ptr" to the start of the next character.
- */
-static inline uint32_t getUtf32FromUtf8(const char** pUtf8Ptr)
-{
-    uint32_t ret;
-    int seq_len;
-    int i;
-
-    /* Mask for leader byte for lengths 1, 2, 3, and 4 respectively*/
-    static const unsigned char leaderMask[4] = {0xff, 0x1f, 0x0f, 0x07};
-
-    /* Bytes that start with bits "10" are not leading characters. */
-    if (((**pUtf8Ptr) & 0xc0) == 0x80) {
-        (*pUtf8Ptr)++;
-        return UTF16_REPLACEMENT_CHAR;
-    }
-
-    /* note we tolerate invalid leader 11111xxx here */    
-    seq_len = UTF8_SEQ_LENGTH(**pUtf8Ptr);
-
-    ret = (**pUtf8Ptr) & leaderMask [seq_len - 1];
-
-    if (**pUtf8Ptr == '\0') return ret;
-
-    (*pUtf8Ptr)++;
-    for (i = 1; i < seq_len ; i++, (*pUtf8Ptr)++) {
-        if ((**pUtf8Ptr) == '\0') return UTF16_REPLACEMENT_CHAR;
-        if (((**pUtf8Ptr) & 0xc0) != 0x80) return UTF16_REPLACEMENT_CHAR;
-
-        UTF8_SHIFT_AND_MASK(ret, **pUtf8Ptr);
-    }
-
-    return ret;
-}
-
-
-/**
- * out_len is an out parameter (which may not be null) containing the
- * length of the UTF-16 string (which may contain embedded \0's)
- */
-
-extern char16_t * strcpy8to16 (char16_t *utf16Str, const char*utf8Str, 
-                                       size_t *out_len)
-{   
-    char16_t *dest = utf16Str;
-
-    while (*utf8Str != '\0') {
-        uint32_t ret;
-
-        ret = getUtf32FromUtf8(&utf8Str);
-
-        if (ret <= 0xffff) {
-            *dest++ = (char16_t) ret;
-        } else if (ret <= UNICODE_UPPER_LIMIT)  {
-            /* Create surrogate pairs */
-            /* See http://en.wikipedia.org/wiki/UTF-16/UCS-2#Method_for_code_points_in_Plane_1.2C_Plane_2 */
-
-            *dest++ = 0xd800 | ((ret - 0x10000) >> 10);
-            *dest++ = 0xdc00 | ((ret - 0x10000) &  0x3ff);
-        } else {
-            *dest++ = UTF16_REPLACEMENT_CHAR;
-        }
-    }
-
-    *out_len = dest - utf16Str;
-
-    return utf16Str;
-}
-
-/**
- * length is the number of characters in the UTF-8 string.
- * out_len is an out parameter (which may not be null) containing the
- * length of the UTF-16 string (which may contain embedded \0's)
- */
-
-extern char16_t * strcpylen8to16 (char16_t *utf16Str, const char*utf8Str,
-                                       int length, size_t *out_len)
-{
-    /* TODO: Share more of this code with the method above. Only 2 lines changed. */
-    
-    char16_t *dest = utf16Str;
-
-    const char *end = utf8Str + length; /* This line */
-    while (utf8Str < end) {             /* and this line changed. */
-        uint32_t ret;
-
-        ret = getUtf32FromUtf8(&utf8Str);
-
-        if (ret <= 0xffff) {
-            *dest++ = (char16_t) ret;
-        } else if (ret <= UNICODE_UPPER_LIMIT)  {
-            /* Create surrogate pairs */
-            /* See http://en.wikipedia.org/wiki/UTF-16/UCS-2#Method_for_code_points_in_Plane_1.2C_Plane_2 */
-
-            *dest++ = 0xd800 | ((ret - 0x10000) >> 10);
-            *dest++ = 0xdc00 | ((ret - 0x10000) &  0x3ff);
-        } else {
-            *dest++ = UTF16_REPLACEMENT_CHAR;
-        }
-    }
-
-    *out_len = dest - utf16Str;
-
-    return utf16Str;
-}
diff --git a/liblog/logger.h b/liblog/logger.h
index 1f632c0..accb6e7 100644
--- a/liblog/logger.h
+++ b/liblog/logger.h
@@ -17,7 +17,6 @@
 #pragma once
 
 #include <stdatomic.h>
-#include <stdbool.h>
 
 #include <cutils/list.h>
 #include <log/log.h>
diff --git a/liblog/logprint.cpp b/liblog/logprint.cpp
index 6b5ea4c..3a54445 100644
--- a/liblog/logprint.cpp
+++ b/liblog/logprint.cpp
@@ -26,7 +26,6 @@
 #ifndef __MINGW32__
 #include <pwd.h>
 #endif
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/liblog/pmsg_reader.cpp b/liblog/pmsg_reader.cpp
index ba27fd7..eaac97f 100644
--- a/liblog/pmsg_reader.cpp
+++ b/liblog/pmsg_reader.cpp
@@ -17,7 +17,6 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
diff --git a/liblog/pmsg_writer.cpp b/liblog/pmsg_writer.cpp
index e851100..4632b32 100644
--- a/liblog/pmsg_writer.cpp
+++ b/liblog/pmsg_writer.cpp
@@ -20,7 +20,6 @@
 
 #include <errno.h>
 #include <fcntl.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
diff --git a/liblog/stderr_write.cpp b/liblog/stderr_write.cpp
index e324a7c..e76673f 100644
--- a/liblog/stderr_write.cpp
+++ b/liblog/stderr_write.cpp
@@ -27,7 +27,6 @@
  */
 
 #include <errno.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/libmodprobe/Android.bp b/libmodprobe/Android.bp
index a2824d1..78da46c 100644
--- a/libmodprobe/Android.bp
+++ b/libmodprobe/Android.bp
@@ -3,6 +3,7 @@
     cflags: [
         "-Werror",
     ],
+    vendor_available: true,
     recovery_available: true,
     srcs: [
         "libmodprobe.cpp",
diff --git a/libmodprobe/OWNERS b/libmodprobe/OWNERS
new file mode 100644
index 0000000..4b770b1
--- /dev/null
+++ b/libmodprobe/OWNERS
@@ -0,0 +1,2 @@
+tomcherry@google.com
+smuckle@google.com
diff --git a/libmodprobe/include/modprobe/modprobe.h b/libmodprobe/include/modprobe/modprobe.h
index 0ec766a..dcb4ffb 100644
--- a/libmodprobe/include/modprobe/modprobe.h
+++ b/libmodprobe/include/modprobe/modprobe.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <set>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -25,12 +26,21 @@
     Modprobe(const std::vector<std::string>&);
 
     bool LoadListedModules();
-    bool LoadWithAliases(const std::string& module_name, bool strict);
+    bool LoadWithAliases(const std::string& module_name, bool strict,
+                         const std::string& parameters = "");
+    bool Remove(const std::string& module_name);
+    std::vector<std::string> ListModules(const std::string& pattern);
+    bool GetAllDependencies(const std::string& module, std::vector<std::string>* pre_dependencies,
+                            std::vector<std::string>* dependencies,
+                            std::vector<std::string>* post_dependencies);
+    void EnableBlacklist(bool enable);
+    void EnableVerbose(bool enable);
 
   private:
     std::string MakeCanonical(const std::string& module_path);
-    bool InsmodWithDeps(const std::string& module_name);
-    bool Insmod(const std::string& path_name);
+    bool InsmodWithDeps(const std::string& module_name, const std::string& parameters);
+    bool Insmod(const std::string& path_name, const std::string& parameters);
+    bool Rmmod(const std::string& module_name);
     std::vector<std::string> GetDependencies(const std::string& module);
     bool ModuleExists(const std::string& module_name);
 
@@ -39,6 +49,7 @@
     bool ParseSoftdepCallback(const std::vector<std::string>& args);
     bool ParseLoadCallback(const std::vector<std::string>& args);
     bool ParseOptionsCallback(const std::vector<std::string>& args);
+    bool ParseBlacklistCallback(const std::vector<std::string>& args);
     void ParseCfg(const std::string& cfg, std::function<bool(const std::vector<std::string>&)> f);
 
     std::vector<std::pair<std::string, std::string>> module_aliases_;
@@ -47,4 +58,6 @@
     std::vector<std::pair<std::string, std::string>> module_post_softdep_;
     std::vector<std::string> module_load_;
     std::unordered_map<std::string, std::string> module_options_;
+    std::set<std::string> module_blacklist_;
+    bool blacklist_enabled = false;
 };
diff --git a/libmodprobe/libmodprobe.cpp b/libmodprobe/libmodprobe.cpp
index 01cf2e3..73ae15b 100644
--- a/libmodprobe/libmodprobe.cpp
+++ b/libmodprobe/libmodprobe.cpp
@@ -194,6 +194,31 @@
     return true;
 }
 
+bool Modprobe::ParseBlacklistCallback(const std::vector<std::string>& args) {
+    auto it = args.begin();
+    const std::string& type = *it++;
+
+    if (type != "blacklist") {
+        LOG(ERROR) << "non-blacklist line encountered in modules.blacklist";
+        return false;
+    }
+
+    if (args.size() != 2) {
+        LOG(ERROR) << "lines in modules.blacklist must have exactly 2 entries, not " << args.size();
+        return false;
+    }
+
+    const std::string& module = *it++;
+
+    const std::string& canonical_name = MakeCanonical(module);
+    if (canonical_name.empty()) {
+        return false;
+    }
+    this->module_blacklist_.emplace(canonical_name);
+
+    return true;
+}
+
 void Modprobe::ParseCfg(const std::string& cfg,
                         std::function<bool(const std::vector<std::string>&)> f) {
     std::string cfg_contents;
@@ -231,6 +256,23 @@
 
         auto options_callback = std::bind(&Modprobe::ParseOptionsCallback, this, _1);
         ParseCfg(base_path + "/modules.options", options_callback);
+
+        auto blacklist_callback = std::bind(&Modprobe::ParseBlacklistCallback, this, _1);
+        ParseCfg(base_path + "/modules.blacklist", blacklist_callback);
+    }
+
+    android::base::SetMinimumLogSeverity(android::base::INFO);
+}
+
+void Modprobe::EnableBlacklist(bool enable) {
+    blacklist_enabled = enable;
+}
+
+void Modprobe::EnableVerbose(bool enable) {
+    if (enable) {
+        android::base::SetMinimumLogSeverity(android::base::VERBOSE);
+    } else {
+        android::base::SetMinimumLogSeverity(android::base::INFO);
     }
 }
 
@@ -242,7 +284,7 @@
     return it->second;
 }
 
-bool Modprobe::InsmodWithDeps(const std::string& module_name) {
+bool Modprobe::InsmodWithDeps(const std::string& module_name, const std::string& parameters) {
     if (module_name.empty()) {
         LOG(ERROR) << "Need valid module name, given: " << module_name;
         return false;
@@ -256,11 +298,8 @@
 
     // load module dependencies in reverse order
     for (auto dep = dependencies.rbegin(); dep != dependencies.rend() - 1; ++dep) {
-        const std::string& canonical_name = MakeCanonical(*dep);
-        if (canonical_name.empty()) {
-            return false;
-        }
-        if (!LoadWithAliases(canonical_name, true)) {
+        LOG(VERBOSE) << "Loading hard dep for '" << module_name << "': " << *dep;
+        if (!LoadWithAliases(*dep, true)) {
             return false;
         }
     }
@@ -268,18 +307,20 @@
     // try to load soft pre-dependencies
     for (const auto& [module, softdep] : module_pre_softdep_) {
         if (module_name == module) {
+            LOG(VERBOSE) << "Loading soft pre-dep for '" << module << "': " << softdep;
             LoadWithAliases(softdep, false);
         }
     }
 
     // load target module itself with args
-    if (!Insmod(dependencies[0])) {
+    if (!Insmod(dependencies[0], parameters)) {
         return false;
     }
 
     // try to load soft post-dependencies
     for (const auto& [module, softdep] : module_post_softdep_) {
         if (module_name == module) {
+            LOG(VERBOSE) << "Loading soft post-dep for '" << module << "': " << softdep;
             LoadWithAliases(softdep, false);
         }
     }
@@ -287,25 +328,27 @@
     return true;
 }
 
-bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict) {
-    std::set<std::string> modules_to_load = {module_name};
+bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict,
+                               const std::string& parameters) {
+    std::set<std::string> modules_to_load = {MakeCanonical(module_name)};
     bool module_loaded = false;
 
     // use aliases to expand list of modules to load (multiple modules
     // may alias themselves to the requested name)
     for (const auto& [alias, aliased_module] : module_aliases_) {
         if (fnmatch(alias.c_str(), module_name.c_str(), 0) != 0) continue;
+        LOG(VERBOSE) << "Found alias for '" << module_name << "': '" << aliased_module;
         modules_to_load.emplace(aliased_module);
     }
 
     // attempt to load all modules aliased to this name
     for (const auto& module : modules_to_load) {
         if (!ModuleExists(module)) continue;
-        if (InsmodWithDeps(module)) module_loaded = true;
+        if (InsmodWithDeps(module, parameters)) module_loaded = true;
     }
 
     if (strict && !module_loaded) {
-        LOG(ERROR) << "LoadWithAliases did not find a module for " << module_name;
+        LOG(ERROR) << "LoadWithAliases was unable to load " << module_name;
         return false;
     }
     return true;
@@ -319,3 +362,64 @@
     }
     return true;
 }
+
+bool Modprobe::Remove(const std::string& module_name) {
+    auto dependencies = GetDependencies(MakeCanonical(module_name));
+    if (dependencies.empty()) {
+        LOG(ERROR) << "Empty dependencies for module " << module_name;
+        return false;
+    }
+    if (!Rmmod(dependencies[0])) {
+        return false;
+    }
+    for (auto dep = dependencies.begin() + 1; dep != dependencies.end(); ++dep) {
+        Rmmod(*dep);
+    }
+    return true;
+}
+
+std::vector<std::string> Modprobe::ListModules(const std::string& pattern) {
+    std::vector<std::string> rv;
+    for (const auto& [module, deps] : module_deps_) {
+        // Attempt to match both the canonical module name and the module filename.
+        if (!fnmatch(pattern.c_str(), module.c_str(), 0)) {
+            rv.emplace_back(module);
+        } else if (!fnmatch(pattern.c_str(), basename(deps[0].c_str()), 0)) {
+            rv.emplace_back(deps[0]);
+        }
+    }
+    return rv;
+}
+
+bool Modprobe::GetAllDependencies(const std::string& module,
+                                  std::vector<std::string>* pre_dependencies,
+                                  std::vector<std::string>* dependencies,
+                                  std::vector<std::string>* post_dependencies) {
+    std::string canonical_name = MakeCanonical(module);
+    if (pre_dependencies) {
+        pre_dependencies->clear();
+        for (const auto& [it_module, it_softdep] : module_pre_softdep_) {
+            if (canonical_name == it_module) {
+                pre_dependencies->emplace_back(it_softdep);
+            }
+        }
+    }
+    if (dependencies) {
+        dependencies->clear();
+        auto hard_deps = GetDependencies(canonical_name);
+        if (hard_deps.empty()) {
+            return false;
+        }
+        for (auto dep = hard_deps.rbegin(); dep != hard_deps.rend(); dep++) {
+            dependencies->emplace_back(*dep);
+        }
+    }
+    if (post_dependencies) {
+        for (const auto& [it_module, it_softdep] : module_post_softdep_) {
+            if (canonical_name == it_module) {
+                post_dependencies->emplace_back(it_softdep);
+            }
+        }
+    }
+    return true;
+}
diff --git a/libmodprobe/libmodprobe_ext.cpp b/libmodprobe/libmodprobe_ext.cpp
index 5f3a04d..2efcac2 100644
--- a/libmodprobe/libmodprobe_ext.cpp
+++ b/libmodprobe/libmodprobe_ext.cpp
@@ -22,7 +22,7 @@
 
 #include <modprobe/modprobe.h>
 
-bool Modprobe::Insmod(const std::string& path_name) {
+bool Modprobe::Insmod(const std::string& path_name, const std::string& parameters) {
     android::base::unique_fd fd(
             TEMP_FAILURE_RETRY(open(path_name.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
     if (fd == -1) {
@@ -35,6 +35,9 @@
     if (options_iter != module_options_.end()) {
         options = options_iter->second;
     }
+    if (!parameters.empty()) {
+        options = options + " " + parameters;
+    }
 
     LOG(INFO) << "Loading module " << path_name << " with args \"" << options << "\"";
     int ret = syscall(__NR_finit_module, fd.get(), options.c_str(), 0);
@@ -51,17 +54,32 @@
     return true;
 }
 
+bool Modprobe::Rmmod(const std::string& module_name) {
+    int ret = syscall(__NR_delete_module, MakeCanonical(module_name).c_str(), O_NONBLOCK);
+    if (ret != 0) {
+        PLOG(ERROR) << "Failed to remove module '" << module_name << "'";
+        return false;
+    }
+    return true;
+}
+
 bool Modprobe::ModuleExists(const std::string& module_name) {
     struct stat fileStat;
+    if (blacklist_enabled && module_blacklist_.count(module_name)) {
+        LOG(INFO) << "module " << module_name << " is blacklisted";
+        return false;
+    }
     auto deps = GetDependencies(module_name);
     if (deps.empty()) {
         // missing deps can happen in the case of an alias
         return false;
     }
     if (stat(deps.front().c_str(), &fileStat)) {
+        LOG(INFO) << "module " << module_name << " does not exist";
         return false;
     }
     if (!S_ISREG(fileStat.st_mode)) {
+        LOG(INFO) << "module " << module_name << " is not a regular file";
         return false;
     }
     return true;
diff --git a/libmodprobe/libmodprobe_ext_test.cpp b/libmodprobe/libmodprobe_ext_test.cpp
index 0f073cb..7d817b1 100644
--- a/libmodprobe/libmodprobe_ext_test.cpp
+++ b/libmodprobe/libmodprobe_ext_test.cpp
@@ -29,7 +29,7 @@
 
 #include "libmodprobe_test.h"
 
-bool Modprobe::Insmod(const std::string& path_name) {
+bool Modprobe::Insmod(const std::string& path_name, const std::string& parameters) {
     auto deps = GetDependencies(MakeCanonical(path_name));
     if (deps.empty()) {
         return false;
@@ -47,12 +47,29 @@
     if (options_iter != module_options_.end()) {
         options = " " + options_iter->second;
     }
+    if (!parameters.empty()) {
+        options = options + " " + parameters;
+    }
+
     modules_loaded.emplace_back(path_name + options);
     return true;
 }
 
+bool Modprobe::Rmmod(const std::string& module_name) {
+    for (auto it = modules_loaded.begin(); it != modules_loaded.end(); it++) {
+        if (*it == module_name) {
+            modules_loaded.erase(it);
+            return true;
+        }
+    }
+    return false;
+}
+
 bool Modprobe::ModuleExists(const std::string& module_name) {
     auto deps = GetDependencies(module_name);
+    if (blacklist_enabled && module_blacklist_.count(module_name)) {
+        return false;
+    }
     if (deps.empty()) {
         // missing deps can happen in the case of an alias
         return false;
diff --git a/libmodprobe/libmodprobe_test.cpp b/libmodprobe/libmodprobe_test.cpp
index 481658d..a711631 100644
--- a/libmodprobe/libmodprobe_test.cpp
+++ b/libmodprobe/libmodprobe_test.cpp
@@ -56,6 +56,14 @@
             "/test13.ko",
     };
 
+    std::vector<std::string> expected_after_remove = {
+            "/test14.ko", "/test15.ko",         "/test1.ko",
+            "/test6.ko",  "/test2.ko",          "/test5.ko",
+            "/test8.ko",  "/test7.ko param1=4", "/test9.ko param_x=1 param_y=2 param_z=3",
+            "/test10.ko", "/test12.ko",         "/test11.ko",
+            "/test13.ko",
+    };
+
     const std::string modules_dep =
             "test1.ko:\n"
             "test2.ko:\n"
@@ -91,6 +99,10 @@
             "options test9.ko param_x=1 param_y=2 param_z=3\n"
             "options test100.ko param_1=1\n";
 
+    const std::string modules_blacklist =
+            "blacklist test9.ko\n"
+            "blacklist test3.ko\n";
+
     const std::string modules_load =
             "test4.ko\n"
             "test1.ko\n"
@@ -101,17 +113,20 @@
             "test11.ko\n";
 
     TemporaryDir dir;
-    ASSERT_TRUE(android::base::WriteStringToFile(
-            modules_alias, std::string(dir.path) + "/modules.alias", 0600, getuid(), getgid()));
+    auto dir_path = std::string(dir.path);
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_alias, dir_path + "/modules.alias", 0600,
+                                                 getuid(), getgid()));
 
-    ASSERT_TRUE(android::base::WriteStringToFile(
-            modules_dep, std::string(dir.path) + "/modules.dep", 0600, getuid(), getgid()));
-    ASSERT_TRUE(android::base::WriteStringToFile(
-            modules_softdep, std::string(dir.path) + "/modules.softdep", 0600, getuid(), getgid()));
-    ASSERT_TRUE(android::base::WriteStringToFile(
-            modules_options, std::string(dir.path) + "/modules.options", 0600, getuid(), getgid()));
-    ASSERT_TRUE(android::base::WriteStringToFile(
-            modules_load, std::string(dir.path) + "/modules.load", 0600, getuid(), getgid()));
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_dep, dir_path + "/modules.dep", 0600,
+                                                 getuid(), getgid()));
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_softdep, dir_path + "/modules.softdep",
+                                                 0600, getuid(), getgid()));
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_options, dir_path + "/modules.options",
+                                                 0600, getuid(), getgid()));
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_load, dir_path + "/modules.load", 0600,
+                                                 getuid(), getgid()));
+    ASSERT_TRUE(android::base::WriteStringToFile(modules_blacklist, dir_path + "/modules.blacklist",
+                                                 0600, getuid(), getgid()));
 
     for (auto i = test_modules.begin(); i != test_modules.end(); ++i) {
         *i = dir.path + *i;
@@ -131,4 +146,21 @@
     }
 
     EXPECT_TRUE(modules_loaded == expected_modules_loaded);
+
+    EXPECT_TRUE(m.Remove("test4"));
+
+    GTEST_LOG_(INFO) << "Expected modules loaded after removing test4 (in order):";
+    for (auto i = expected_after_remove.begin(); i != expected_after_remove.end(); ++i) {
+        *i = dir.path + *i;
+        GTEST_LOG_(INFO) << "\"" << *i << "\"";
+    }
+    GTEST_LOG_(INFO) << "Actual modules loaded after removing test4 (in order):";
+    for (auto i = modules_loaded.begin(); i != modules_loaded.end(); ++i) {
+        GTEST_LOG_(INFO) << "\"" << *i << "\"";
+    }
+
+    EXPECT_TRUE(modules_loaded == expected_after_remove);
+
+    m.EnableBlacklist(true);
+    EXPECT_FALSE(m.LoadWithAliases("test4", true));
 }
diff --git a/libnativeloader/native_loader_namespace.cpp b/libnativeloader/native_loader_namespace.cpp
index 4b02116..4add6e6 100644
--- a/libnativeloader/native_loader_namespace.cpp
+++ b/libnativeloader/native_loader_namespace.cpp
@@ -69,10 +69,18 @@
 // "default" always exists.
 Result<NativeLoaderNamespace> NativeLoaderNamespace::GetPlatformNamespace(bool is_bridged) {
   auto ns = GetExportedNamespace(kPlatformNamespaceName, is_bridged);
-  if (!ns) {
-    ns = GetExportedNamespace(kDefaultNamespaceName, is_bridged);
+  if (ns) return ns;
+  ns = GetExportedNamespace(kDefaultNamespaceName, is_bridged);
+  if (ns) return ns;
+
+  // If nothing is found, return NativeLoaderNamespace constructed from nullptr.
+  // nullptr also means default namespace to the linker.
+  if (!is_bridged) {
+    return NativeLoaderNamespace(kDefaultNamespaceName, static_cast<android_namespace_t*>(nullptr));
+  } else {
+    return NativeLoaderNamespace(kDefaultNamespaceName,
+                                 static_cast<native_bridge_namespace_t*>(nullptr));
   }
-  return ns;
 }
 
 Result<NativeLoaderNamespace> NativeLoaderNamespace::Create(
diff --git a/libstats/include/stats_event_list.h b/libstats/include/stats_event_list.h
index 845a197..b7ada0c 100644
--- a/libstats/include/stats_event_list.h
+++ b/libstats/include/stats_event_list.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_STATS_LOG_STATS_EVENT_LIST_H
-#define ANDROID_STATS_LOG_STATS_EVENT_LIST_H
+#pragma once
 
 #include <log/log_event_list.h>
 #include <sys/uio.h>
@@ -133,7 +132,6 @@
         return *this;
     }
 
-#if defined(_USING_LIBCXX)
     stats_event_list& operator<<(const std::string& value) {
         int retval = android_log_write_string8_len(ctx, value.data(), value.length());
         if (retval < 0) {
@@ -141,7 +139,6 @@
         }
         return *this;
     }
-#endif
 
     stats_event_list& operator<<(float value) {
         int retval = android_log_write_float32(ctx, value);
@@ -203,7 +200,6 @@
         return ret >= 0;
     }
 
-#if defined(_USING_LIBCXX)
     bool AppendString(const std::string& value) {
         int retval = android_log_write_string8_len(ctx, value.data(), value.length());
         if (retval < 0) {
@@ -219,7 +215,6 @@
         }
         return ret;
     }
-#endif
 
     bool AppendFloat(float value) {
         int retval = android_log_write_float32(ctx, value);
@@ -253,4 +248,3 @@
 };
 
 #endif
-#endif  // ANDROID_STATS_LOG_STATS_EVENT_LIST_H
diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index 24a745a..b08e061 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -452,48 +452,6 @@
     *codePoint |= 0x3F & byte;
 }
 
-size_t utf8_to_utf32_length(const char *src, size_t src_len)
-{
-    if (src == nullptr || src_len == 0) {
-        return 0;
-    }
-    size_t ret = 0;
-    const char* cur;
-    const char* end;
-    size_t num_to_skip;
-    for (cur = src, end = src + src_len, num_to_skip = 1;
-         cur < end;
-         cur += num_to_skip, ret++) {
-        const char first_char = *cur;
-        num_to_skip = 1;
-        if ((first_char & 0x80) == 0) {  // ASCII
-            continue;
-        }
-        int32_t mask;
-
-        for (mask = 0x40; (first_char & mask); num_to_skip++, mask >>= 1) {
-        }
-    }
-    return ret;
-}
-
-void utf8_to_utf32(const char* src, size_t src_len, char32_t* dst)
-{
-    if (src == nullptr || src_len == 0 || dst == nullptr) {
-        return;
-    }
-
-    const char* cur = src;
-    const char* const end = src + src_len;
-    char32_t* cur_utf32 = dst;
-    while (cur < end) {
-        size_t num_read;
-        *cur_utf32++ = static_cast<char32_t>(utf32_at_internal(cur, &num_read));
-        cur += num_read;
-    }
-    *cur_utf32 = 0;
-}
-
 static inline uint32_t utf8_to_utf32_codepoint(const uint8_t *src, size_t length)
 {
     uint32_t unicode;
diff --git a/libutils/include/utils/Unicode.h b/libutils/include/utils/Unicode.h
index a2aaa47..fc6712d 100644
--- a/libutils/include/utils/Unicode.h
+++ b/libutils/include/utils/Unicode.h
@@ -129,18 +129,6 @@
 ssize_t utf8_length(const char *src);
 
 /**
- * Measure the length of a UTF-32 string.
- */
-size_t utf8_to_utf32_length(const char *src, size_t src_len);
-
-/**
- * Stores a UTF-32 string converted from "src" in "dst". "dst" must be large
- * enough to store the entire converted string as measured by
- * utf8_to_utf32_length plus space for a NUL terminator.
- */
-void utf8_to_utf32(const char* src, size_t src_len, char32_t* dst);
-
-/**
  * Returns the UTF-16 length of UTF-8 string "src". Returns -1 in case
  * it's invalid utf8. No buffer over-read occurs because of bound checks. Using overreadIsFatal you
  * can ask to log a message and fail in case the invalid utf8 could have caused an override if no
diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 6e38d95..6507711 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -899,6 +899,11 @@
             case 0:
                 // only long options
                 if (long_options[option_index].name == pid_str) {
+                    if (pid != 0) {
+                        logcat_panic(context, HELP_TRUE, "Only supports one PID argument.\n");
+                        goto exit;
+                    }
+
                     // ToDo: determine runtime PID_MAX?
                     if (!getSizeTArg(optarg, &pid, 1)) {
                         logcat_panic(context, HELP_TRUE, "%s %s out of range\n",
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index 76d6f7e..4559050 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -230,7 +230,7 @@
 # A symlink can't overwrite a directory and the /system/usr/icu directory once
 # existed so the required structure must be created whatever we find.
 LOCAL_POST_INSTALL_CMD = mkdir -p $(TARGET_OUT)/usr && rm -rf $(TARGET_OUT)/usr/icu
-LOCAL_POST_INSTALL_CMD += && ln -sf /apex/com.android.runtime/etc/icu $(TARGET_OUT)/usr/icu
+LOCAL_POST_INSTALL_CMD += && ln -sf /apex/com.android.i18n/etc/icu $(TARGET_OUT)/usr/icu
 
 # TODO(b/124106384): Clean up compat symlinks for ART binaries.
 ART_BINARIES := \
diff --git a/rootdir/init.environ.rc.in b/rootdir/init.environ.rc.in
index 455c9a8..93b7f43 100644
--- a/rootdir/init.environ.rc.in
+++ b/rootdir/init.environ.rc.in
@@ -6,6 +6,7 @@
     export ANDROID_DATA /data
     export ANDROID_STORAGE /storage
     export ANDROID_RUNTIME_ROOT /apex/com.android.runtime
+    export ANDROID_I18N_ROOT /apex/com.android.i18n
     export ANDROID_TZDATA_ROOT /apex/com.android.tzdata
     export EXTERNAL_STORAGE /sdcard
     export ASEC_MOUNTPOINT /mnt/asec
diff --git a/rootdir/init.rc b/rootdir/init.rc
index d22e9a7..86d8042 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -415,6 +415,7 @@
     chmod 0700 /metadata/vold
     mkdir /metadata/password_slots 0771 root system
     mkdir /metadata/ota 0700 root system
+    mkdir /metadata/ota/snapshots 0700 root system
 
     mkdir /metadata/apex 0700 root system
     mkdir /metadata/apex/sessions 0700 root system
diff --git a/storaged/storaged.cpp b/storaged/storaged.cpp
index 6897663..1d934a2 100644
--- a/storaged/storaged.cpp
+++ b/storaged/storaged.cpp
@@ -164,8 +164,10 @@
 }
 
 void storaged_t::add_user_ce(userid_t user_id) {
-    load_proto(user_id);
-    proto_loaded[user_id] = true;
+    if (!proto_loaded[user_id]) {
+        load_proto(user_id);
+        proto_loaded[user_id] = true;
+    }
 }
 
 void storaged_t::remove_user_ce(userid_t user_id) {
diff --git a/toolbox/Android.bp b/toolbox/Android.bp
index 0cc603a..4ca5f5a 100644
--- a/toolbox/Android.bp
+++ b/toolbox/Android.bp
@@ -24,6 +24,7 @@
         "toolbox.c",
         "getevent.c",
         "getprop.cpp",
+        "modprobe.cpp",
         "setprop.cpp",
         "start.cpp",
     ],
@@ -33,11 +34,15 @@
     shared_libs: [
         "libbase",
     ],
-    static_libs: ["libpropertyinfoparser"],
+    static_libs: [
+        "libmodprobe",
+        "libpropertyinfoparser",
+    ],
 
     symlinks: [
         "getevent",
         "getprop",
+        "modprobe",
         "setprop",
         "start",
         "stop",
diff --git a/toolbox/modprobe.cpp b/toolbox/modprobe.cpp
new file mode 100644
index 0000000..1b5f54e
--- /dev/null
+++ b/toolbox/modprobe.cpp
@@ -0,0 +1,201 @@
+/*
+ * 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 <ctype.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <iostream>
+
+#include <android-base/strings.h>
+#include <modprobe/modprobe.h>
+
+enum modprobe_mode {
+    AddModulesMode,
+    RemoveModulesMode,
+    ListModulesMode,
+    ShowDependenciesMode,
+};
+
+static void print_usage(void) {
+    std::cerr << "Usage:" << std::endl;
+    std::cerr << std::endl;
+    std::cerr << "  modprobe [-alrqvsDb] [-d DIR] [MODULE]+" << std::endl;
+    std::cerr << "  modprobe [-alrqvsDb] [-d DIR] MODULE [symbol=value][...]" << std::endl;
+    std::cerr << std::endl;
+    std::cerr << "Options:" << std::endl;
+    std::cerr << "  -b: Apply blacklist to module names too" << std::endl;
+    std::cerr << "  -d: Load modules from DIR, option may be used multiple times" << std::endl;
+    std::cerr << "  -D: Print dependencies for modules only, do not load";
+    std::cerr << "  -h: Print this help" << std::endl;
+    std::cerr << "  -l: List modules matching pattern" << std::endl;
+    std::cerr << "  -r: Remove MODULE (multiple modules may be specified)" << std::endl;
+    std::cerr << "  -q: Quiet" << std::endl;
+    std::cerr << "  -v: Verbose" << std::endl;
+    std::cerr << std::endl;
+}
+
+#define check_mode()                                                      \
+    if (mode != AddModulesMode) {                                         \
+        std::cerr << "Error, multiple mode flags specified" << std::endl; \
+        print_usage();                                                    \
+        return EXIT_FAILURE;                                              \
+    }
+
+extern "C" int modprobe_main(int argc, char** argv) {
+    std::vector<std::string> modules;
+    std::string module_parameters;
+    std::vector<std::string> mod_dirs;
+    modprobe_mode mode = AddModulesMode;
+    bool blacklist = false;
+    bool verbose = false;
+    int rv = EXIT_SUCCESS;
+
+    int opt;
+    while ((opt = getopt(argc, argv, "abd:Dhlqrv")) != -1) {
+        switch (opt) {
+            case 'a':
+                // toybox modprobe supported -a to load multiple modules, this
+                // is supported here by default, ignore flag
+                check_mode();
+                break;
+            case 'b':
+                blacklist = true;
+                break;
+            case 'd':
+                mod_dirs.emplace_back(optarg);
+                break;
+            case 'D':
+                check_mode();
+                mode = ShowDependenciesMode;
+                break;
+            case 'h':
+                print_usage();
+                return EXIT_SUCCESS;
+            case 'l':
+                check_mode();
+                mode = ListModulesMode;
+                break;
+            case 'q':
+                verbose = false;
+                break;
+            case 'r':
+                check_mode();
+                mode = RemoveModulesMode;
+                break;
+            case 'v':
+                verbose = true;
+                break;
+            default:
+                std::cerr << "Unrecognized option: " << opt << std::endl;
+                return EXIT_FAILURE;
+        }
+    }
+
+    int parameter_count = 0;
+    for (opt = optind; opt < argc; opt++) {
+        if (!strchr(argv[opt], '=')) {
+            modules.emplace_back(argv[opt]);
+        } else {
+            parameter_count++;
+            if (module_parameters.empty()) {
+                module_parameters = argv[opt];
+            } else {
+                module_parameters = module_parameters + " " + argv[opt];
+            }
+        }
+    }
+
+    if (verbose) {
+        std::cout << "mode is " << mode << std::endl;
+        std::cout << "verbose is " << verbose << std::endl;
+        std::cout << "mod_dirs is: " << android::base::Join(mod_dirs, "") << std::endl;
+        std::cout << "modules is: " << android::base::Join(modules, "") << std::endl;
+        std::cout << "module parameters is: " << android::base::Join(module_parameters, "")
+                  << std::endl;
+    }
+
+    if (modules.empty()) {
+        if (mode == ListModulesMode) {
+            // emulate toybox modprobe list with no pattern (list all)
+            modules.emplace_back("*");
+        } else {
+            std::cerr << "No modules given." << std::endl;
+            print_usage();
+            return EXIT_FAILURE;
+        }
+    }
+    if (mod_dirs.empty()) {
+        std::cerr << "No module configuration directories given." << std::endl;
+        print_usage();
+        return EXIT_FAILURE;
+    }
+    if (parameter_count && modules.size() > 1) {
+        std::cerr << "Only one module may be loaded when specifying module parameters."
+                  << std::endl;
+        print_usage();
+        return EXIT_FAILURE;
+    }
+
+    Modprobe m(mod_dirs);
+    m.EnableVerbose(verbose);
+    if (blacklist) {
+        m.EnableBlacklist(true);
+    }
+
+    for (const auto& module : modules) {
+        switch (mode) {
+            case AddModulesMode:
+                if (!m.LoadWithAliases(module, true, module_parameters)) {
+                    std::cerr << "Failed to load module " << module;
+                    rv = EXIT_FAILURE;
+                }
+                break;
+            case RemoveModulesMode:
+                if (!m.Remove(module)) {
+                    std::cerr << "Failed to remove module " << module;
+                    rv = EXIT_FAILURE;
+                }
+                break;
+            case ListModulesMode: {
+                std::vector<std::string> list = m.ListModules(module);
+                std::cout << android::base::Join(list, "\n") << std::endl;
+                break;
+            }
+            case ShowDependenciesMode: {
+                std::vector<std::string> pre_deps;
+                std::vector<std::string> deps;
+                std::vector<std::string> post_deps;
+                if (!m.GetAllDependencies(module, &pre_deps, &deps, &post_deps)) {
+                    rv = EXIT_FAILURE;
+                    break;
+                }
+                std::cout << "Dependencies for " << module << ":" << std::endl;
+                std::cout << "Soft pre-dependencies:" << std::endl;
+                std::cout << android::base::Join(pre_deps, "\n") << std::endl;
+                std::cout << "Hard dependencies:" << std::endl;
+                std::cout << android::base::Join(deps, "\n") << std::endl;
+                std::cout << "Soft post-dependencies:" << std::endl;
+                std::cout << android::base::Join(post_deps, "\n") << std::endl;
+                break;
+            }
+            default:
+                std::cerr << "Bad mode";
+                rv = EXIT_FAILURE;
+        }
+    }
+
+    return rv;
+}
diff --git a/toolbox/tools.h b/toolbox/tools.h
index 9a7ebd2..bb57e67 100644
--- a/toolbox/tools.h
+++ b/toolbox/tools.h
@@ -1,5 +1,6 @@
 TOOL(getevent)
 TOOL(getprop)
+TOOL(modprobe)
 TOOL(setprop)
 TOOL(start)
 TOOL(stop)