diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index a00a202..39d7fff 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -20,6 +20,7 @@
 #include <fcntl.h>
 #include <linux/prctl.h>
 #include <malloc.h>
+#include <pthread.h>
 #include <stdlib.h>
 #include <sys/capability.h>
 #include <sys/mman.h>
@@ -2703,3 +2704,58 @@
   }
   ASSERT_TRUE(found_valid_elf) << "Did not find any elf files with valid BuildIDs to check.";
 }
+
+const char kLogMessage[] = "Should not see this log message.";
+
+// Verify that the logd process does not read the log.
+TEST_F(CrasherTest, logd_skips_reading_logs) {
+  StartProcess([]() {
+    pthread_setname_np(pthread_self(), "logd");
+    LOG(INFO) << kLogMessage;
+    abort();
+  });
+
+  unique_fd output_fd;
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  AssertDeath(SIGABRT);
+  int intercept_result;
+  FinishIntercept(&intercept_result);
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  // logd should not contain our log message.
+  ASSERT_NOT_MATCH(result, kLogMessage);
+}
+
+// Verify that the logd process does not read the log when the non-main
+// thread crashes.
+TEST_F(CrasherTest, logd_skips_reading_logs_not_main_thread) {
+  StartProcess([]() {
+    pthread_setname_np(pthread_self(), "logd");
+    LOG(INFO) << kLogMessage;
+
+    std::thread thread([]() {
+      pthread_setname_np(pthread_self(), "not_logd_thread");
+      // Raise the signal on the side thread.
+      raise_debugger_signal(kDebuggerdTombstone);
+    });
+    thread.join();
+    _exit(0);
+  });
+
+  unique_fd output_fd;
+  StartIntercept(&output_fd, kDebuggerdTombstone);
+  FinishCrasher();
+  AssertDeath(0);
+
+  int intercept_result;
+  FinishIntercept(&intercept_result);
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_BACKTRACE_FRAME(result, "raise_debugger_signal");
+  ASSERT_NOT_MATCH(result, kLogMessage);
+}
diff --git a/debuggerd/libdebuggerd/tombstone_proto.cpp b/debuggerd/libdebuggerd/tombstone_proto.cpp
index 9a565de..acd814e 100644
--- a/debuggerd/libdebuggerd/tombstone_proto.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto.cpp
@@ -690,7 +690,14 @@
 
   // Only dump logs on debuggable devices.
   if (android::base::GetBoolProperty("ro.debuggable", false)) {
-    dump_logcat(&result, main_thread.pid);
+    // Get the thread that corresponds to the main pid of the process.
+    const ThreadInfo& thread = threads.at(main_thread.pid);
+
+    // Do not attempt to dump logs of the logd process because the gathering
+    // of logs can hang until a timeout occurs.
+    if (thread.thread_name != "logd") {
+      dump_logcat(&result, main_thread.pid);
+    }
   }
 
   dump_open_fds(&result, open_files);
diff --git a/fastboot/fastboot_driver_mock.h b/fastboot/fastboot_driver_mock.h
index 62a5708..d2a123b 100644
--- a/fastboot/fastboot_driver_mock.h
+++ b/fastboot/fastboot_driver_mock.h
@@ -22,8 +22,7 @@
 
 class MockFastbootDriver : public IFastBootDriver {
   public:
-    MOCK_METHOD(RetCode, FlashPartition,
-                (const std::string& partition, android::base::borrowed_fd fd, uint32_t sz),
+    MOCK_METHOD(RetCode, FlashPartition, (const std::string&, android::base::borrowed_fd, uint32_t),
                 (override));
     MOCK_METHOD(RetCode, DeletePartition, (const std::string&), (override));
     MOCK_METHOD(RetCode, Reboot, (std::string*, std::vector<std::string>*), (override));
diff --git a/fastboot/task.cpp b/fastboot/task.cpp
index 054c1ed..ce46e91 100644
--- a/fastboot/task.cpp
+++ b/fastboot/task.cpp
@@ -65,7 +65,7 @@
     : reboot_target_(reboot_target), fp_(fp){};
 
 void RebootTask::Run() {
-    if ((reboot_target_ == "userspace" || reboot_target_ == "fastboot")) {
+    if (reboot_target_ == "fastboot") {
         if (!is_userspace_fastboot()) {
             reboot_to_userspace_fastboot();
             fp_->fb->WaitForDisconnect();
diff --git a/fastboot/task_test.cpp b/fastboot/task_test.cpp
index 145b4d7..6fc2056 100644
--- a/fastboot/task_test.cpp
+++ b/fastboot/task_test.cpp
@@ -16,6 +16,7 @@
 
 #include "task.h"
 #include "fastboot.h"
+#include "fastboot_driver_mock.h"
 
 #include <gtest/gtest.h>
 #include <fstream>
@@ -24,6 +25,7 @@
 #include <unordered_map>
 #include "android-base/strings.h"
 using android::base::Split;
+using testing::_;
 
 class ParseTest : public ::testing ::Test {
   protected:
@@ -58,7 +60,7 @@
     return ParseFastbootInfoLine(fp, vec_command);
 }
 
-TEST_F(ParseTest, CORRECT_FlASH_TASK_FORMED) {
+TEST_F(ParseTest, CorrectFlashTaskFormed) {
     std::vector<std::string> commands = {"flash dtbo", "flash --slot-other system system_other.img",
                                          "flash system", "flash --apply-vbmeta vbmeta"};
 
@@ -86,7 +88,7 @@
     }
 }
 
-TEST_F(ParseTest, VERSION_CHECK_CORRRECT) {
+TEST_F(ParseTest, VersionCheckCorrect) {
     std::vector<std::string> correct_versions = {
             "version 1.0",
             "version 22.00",
@@ -104,7 +106,7 @@
     }
 }
 
-TEST_F(ParseTest, BAD_FASTBOOT_INFO_INPUT) {
+TEST_F(ParseTest, BadFastbootInput) {
     ASSERT_EQ(ParseCommand(fp.get(), "flash"), nullptr);
     ASSERT_EQ(ParseCommand(fp.get(), "flash --slot-other --apply-vbmeta"), nullptr);
     ASSERT_EQ(ParseCommand(fp.get(), "flash --apply-vbmeta"), nullptr);
@@ -121,3 +123,32 @@
     ASSERT_EQ(ParseCommand(fp.get(), "erase dtbo dtbo"), nullptr);
     ASSERT_EQ(ParseCommand(fp.get(), "wipe this"), nullptr);
 }
+
+TEST_F(ParseTest, CorrectTaskFormed) {
+    std::vector<std::string> commands = {"flash dtbo", "flash --slot-other system system_other.img",
+                                         "reboot bootloader", "update-super", "erase cache"};
+    std::vector<std::unique_ptr<Task>> tasks = collectTasks(fp.get(), commands);
+
+    ASSERT_TRUE(tasks[0]->AsFlashTask());
+    ASSERT_TRUE(tasks[0]->AsFlashTask());
+    ASSERT_TRUE(tasks[1]->AsFlashTask());
+    ASSERT_TRUE(tasks[2]->AsRebootTask());
+    ASSERT_TRUE(tasks[3]->AsUpdateSuperTask());
+    ASSERT_TRUE(tasks[4]->AsWipeTask());
+}
+
+TEST_F(ParseTest, CorrectDriverCalls) {
+    fastboot::MockFastbootDriver fb;
+    fp->fb = &fb;
+
+    EXPECT_CALL(fb, RebootTo(_, _, _)).Times(1);
+    EXPECT_CALL(fb, Reboot(_, _)).Times(1);
+    EXPECT_CALL(fb, WaitForDisconnect()).Times(2);
+
+    std::vector<std::string> commands = {"reboot bootloader", "reboot"};
+    std::vector<std::unique_ptr<Task>> tasks = collectTasks(fp.get(), commands);
+
+    for (auto& task : tasks) {
+        task->Run();
+    }
+}
diff --git a/fs_mgr/TEST_MAPPING b/fs_mgr/TEST_MAPPING
index db27cf0..d357e45 100644
--- a/fs_mgr/TEST_MAPPING
+++ b/fs_mgr/TEST_MAPPING
@@ -24,9 +24,8 @@
     {
       "name": "vab_legacy_tests"
     },
-    {
-      "name": "vabc_legacy_tests"
-    },
+    // TODO: b/279009697
+    //{"name": "vabc_legacy_tests"},
     {
       "name": "cow_api_test"
     }
@@ -43,9 +42,8 @@
     },
     {
       "name": "vab_legacy_tests"
-    },
-    {
-      "name": "vabc_legacy_tests"
     }
+    // TODO: b/279009697
+    //{"name": "vabc_legacy_tests"}
   ]
 }
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index ba75a8d..69079cb 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -15,7 +15,9 @@
 #pragma once
 
 #include <stdint.h>
-#include <string>
+
+#include <optional>
+#include <string_view>
 
 namespace android {
 namespace snapshot {
@@ -196,5 +198,8 @@
 // Ops that have dependencies on old blocks, and must take care in their merge order
 bool IsOrderedOp(const CowOperation& op);
 
+// Convert compression name to internal value.
+std::optional<CowCompressionAlgorithm> CompressionAlgorithmFromString(std::string_view name);
+
 }  // namespace snapshot
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
index e8e4d72..73429e1 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
@@ -29,42 +29,13 @@
 
 class ICowOpIter;
 
-// A ByteSink object handles requests for a buffer of a specific size. It
-// always owns the underlying buffer. It's designed to minimize potential
-// copying as we parse or decompress the COW.
-class IByteSink {
-  public:
-    virtual ~IByteSink() {}
-
-    // Called when the reader has data. The size of the request is given. The
-    // sink must return a valid pointer (or null on failure), and return the
-    // maximum number of bytes that can be written to the returned buffer.
-    //
-    // The returned buffer is owned by IByteSink, but must remain valid until
-    // the read operation has completed (or the entire buffer has been
-    // covered by calls to ReturnData).
-    //
-    // After calling GetBuffer(), all previous buffers returned are no longer
-    // valid.
-    //
-    // GetBuffer() is intended to be sequential. A returned size of N indicates
-    // that the output stream will advance by N bytes, and the ReturnData call
-    // indicates that those bytes have been fulfilled. Therefore, it is
-    // possible to have ReturnBuffer do nothing, if the implementation doesn't
-    // care about incremental writes.
-    virtual void* GetBuffer(size_t requested, size_t* actual) = 0;
-
-    // Called when a section returned by |GetBuffer| has been filled with data.
-    virtual bool ReturnData(void* buffer, size_t length) = 0;
-};
-
 // Interface for reading from a snapuserd COW.
 class ICowReader {
   public:
     virtual ~ICowReader() {}
 
     // Return the file header.
-    virtual bool GetHeader(CowHeader* header) = 0;
+    virtual CowHeader& GetHeader() = 0;
 
     // Return the file footer.
     virtual bool GetFooter(CowFooter* footer) = 0;
@@ -83,17 +54,27 @@
     virtual std::unique_ptr<ICowOpIter> GetMergeOpIter(bool ignore_progress) = 0;
 
     // Get decoded bytes from the data section, handling any decompression.
-    // All retrieved data is passed to the sink.
-    virtual bool ReadData(const CowOperation& op, IByteSink* sink) = 0;
+    //
+    // If ignore_bytes is non-zero, it specifies the initial number of bytes
+    // to skip writing to |buffer|.
+    //
+    // Returns the number of bytes written to |buffer|, or -1 on failure.
+    // errno is NOT set.
+    //
+    // Partial reads are not possible unless |buffer_size| is less than the
+    // operation block size.
+    virtual ssize_t ReadData(const CowOperation& op, void* buffer, size_t buffer_size,
+                             size_t ignore_bytes = 0) = 0;
 };
 
-// Iterate over a sequence of COW operations.
+// Iterate over a sequence of COW operations. The iterator is bidirectional.
 class ICowOpIter {
   public:
     virtual ~ICowOpIter() {}
 
-    // True if there are no more items to read forward, false otherwise.
-    virtual bool Done() = 0;
+    // Returns true if the iterator is at the end of the operation list.
+    // If true, Get() and Next() must not be called.
+    virtual bool AtEnd() = 0;
 
     // Read the current operation.
     virtual const CowOperation& Get() = 0;
@@ -101,11 +82,13 @@
     // Advance to the next item.
     virtual void Next() = 0;
 
+    // Returns true if the iterator is at the beginning of the operation list.
+    // If true, Prev() must not be called; Get() however will be valid if
+    // AtEnd() is not true.
+    virtual bool AtBegin() = 0;
+
     // Advance to the previous item.
     virtual void Prev() = 0;
-
-    // True if there are no more items to read backwards, false otherwise
-    virtual bool RDone() = 0;
 };
 
 class CowReader final : public ICowReader {
@@ -126,7 +109,6 @@
     bool InitForMerge(android::base::unique_fd&& fd);
     bool VerifyMergeOps() override;
 
-    bool GetHeader(CowHeader* header) override;
     bool GetFooter(CowFooter* footer) override;
 
     bool GetLastLabel(uint64_t* label) override;
@@ -139,7 +121,10 @@
     std::unique_ptr<ICowOpIter> GetRevMergeOpIter(bool ignore_progress = false) override;
     std::unique_ptr<ICowOpIter> GetMergeOpIter(bool ignore_progress = false) override;
 
-    bool ReadData(const CowOperation& op, IByteSink* sink) override;
+    ssize_t ReadData(const CowOperation& op, void* buffer, size_t buffer_size,
+                     size_t ignore_bytes = 0) override;
+
+    CowHeader& GetHeader() override { return header_; }
 
     bool GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read);
 
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
index 862ce55..7d1b7ba 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
@@ -24,6 +24,7 @@
 #include <gtest/gtest.h>
 #include <libsnapshot/cow_reader.h>
 #include <libsnapshot/cow_writer.h>
+#include "cow_decompress.h"
 
 using testing::AssertionFailure;
 using testing::AssertionResult;
@@ -44,23 +45,10 @@
     std::unique_ptr<TemporaryFile> cow_;
 };
 
-// Sink that always appends to the end of a string.
-class StringSink : public IByteSink {
-  public:
-    void* GetBuffer(size_t requested, size_t* actual) override {
-        size_t old_size = stream_.size();
-        stream_.resize(old_size + requested, '\0');
-        *actual = requested;
-        return stream_.data() + old_size;
-    }
-    bool ReturnData(void*, size_t) override { return true; }
-    void Reset() { stream_.clear(); }
-
-    std::string& stream() { return stream_; }
-
-  private:
-    std::string stream_;
-};
+// Helper to check read sizes.
+static inline bool ReadData(CowReader& reader, const CowOperation& op, void* buffer, size_t size) {
+    return reader.ReadData(op, buffer, size) == size;
+}
 
 TEST_F(CowTest, CopyContiguous) {
     CowOptions options;
@@ -74,23 +62,24 @@
     ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
 
     CowReader reader;
-    CowHeader header;
-    CowFooter footer;
     ASSERT_TRUE(reader.Parse(cow_->fd));
-    ASSERT_TRUE(reader.GetHeader(&header));
-    ASSERT_TRUE(reader.GetFooter(&footer));
+
+    const auto& header = reader.GetHeader();
     ASSERT_EQ(header.magic, kCowMagicNumber);
     ASSERT_EQ(header.major_version, kCowVersionMajor);
     ASSERT_EQ(header.minor_version, kCowVersionMinor);
     ASSERT_EQ(header.block_size, options.block_size);
+
+    CowFooter footer;
+    ASSERT_TRUE(reader.GetFooter(&footer));
     ASSERT_EQ(footer.op.num_ops, 100);
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
 
     size_t i = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         auto op = &iter->Get();
         ASSERT_EQ(op->type, kCowCopyOp);
         ASSERT_EQ(op->compression, kCowCompressNone);
@@ -122,20 +111,21 @@
     ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
 
     CowReader reader;
-    CowHeader header;
-    CowFooter footer;
     ASSERT_TRUE(reader.Parse(cow_->fd));
-    ASSERT_TRUE(reader.GetHeader(&header));
-    ASSERT_TRUE(reader.GetFooter(&footer));
+
+    const auto& header = reader.GetHeader();
     ASSERT_EQ(header.magic, kCowMagicNumber);
     ASSERT_EQ(header.major_version, kCowVersionMajor);
     ASSERT_EQ(header.minor_version, kCowVersionMinor);
     ASSERT_EQ(header.block_size, options.block_size);
+
+    CowFooter footer;
+    ASSERT_TRUE(reader.GetFooter(&footer));
     ASSERT_EQ(footer.op.num_ops, 4);
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowCopyOp);
@@ -144,21 +134,21 @@
     ASSERT_EQ(op->new_block, 10);
     ASSERT_EQ(op->source, 20);
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowReplaceOp);
     ASSERT_EQ(op->compression, kCowCompressNone);
     ASSERT_EQ(op->data_length, 4096);
     ASSERT_EQ(op->new_block, 50);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     // Note: the zero operation gets split into two blocks.
@@ -169,7 +159,7 @@
     ASSERT_EQ(op->source, 0);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowZeroOp);
@@ -179,7 +169,7 @@
     ASSERT_EQ(op->source, 0);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, ReadWriteXor) {
@@ -200,20 +190,21 @@
     ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
 
     CowReader reader;
-    CowHeader header;
-    CowFooter footer;
     ASSERT_TRUE(reader.Parse(cow_->fd));
-    ASSERT_TRUE(reader.GetHeader(&header));
-    ASSERT_TRUE(reader.GetFooter(&footer));
+
+    const auto& header = reader.GetHeader();
     ASSERT_EQ(header.magic, kCowMagicNumber);
     ASSERT_EQ(header.major_version, kCowVersionMajor);
     ASSERT_EQ(header.minor_version, kCowVersionMinor);
     ASSERT_EQ(header.block_size, options.block_size);
+
+    CowFooter footer;
+    ASSERT_TRUE(reader.GetFooter(&footer));
     ASSERT_EQ(footer.op.num_ops, 4);
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowCopyOp);
@@ -222,10 +213,10 @@
     ASSERT_EQ(op->new_block, 10);
     ASSERT_EQ(op->source, 20);
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowXorOp);
@@ -233,11 +224,11 @@
     ASSERT_EQ(op->data_length, 4096);
     ASSERT_EQ(op->new_block, 50);
     ASSERT_EQ(op->source, 98314);  // 4096 * 24 + 10
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     // Note: the zero operation gets split into two blocks.
@@ -248,7 +239,7 @@
     ASSERT_EQ(op->source, 0);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowZeroOp);
@@ -258,7 +249,7 @@
     ASSERT_EQ(op->source, 0);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, CompressGz) {
@@ -282,25 +273,25 @@
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     ASSERT_EQ(op->type, kCowReplaceOp);
     ASSERT_EQ(op->compression, kCowCompressGz);
     ASSERT_EQ(op->data_length, 56);  // compressed!
     ASSERT_EQ(op->new_block, 50);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
-class CompressionRWTest : public CowTest, public testing::WithParamInterface<const char*> {};
+class CompressionTest : public CowTest, public testing::WithParamInterface<const char*> {};
 
-TEST_P(CompressionRWTest, ThreadedBatchWrites) {
+TEST_P(CompressionTest, ThreadedBatchWrites) {
     CowOptions options;
     options.compression = GetParam();
     options.num_compress_threads = 2;
@@ -337,36 +328,37 @@
     ASSERT_NE(iter, nullptr);
 
     int total_blocks = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         auto op = &iter->Get();
 
         if (op->type == kCowXorOp) {
             total_blocks += 1;
-            StringSink sink;
+            std::string sink(xor_data.size(), '\0');
             ASSERT_EQ(op->new_block, 50);
             ASSERT_EQ(op->source, 98314);  // 4096 * 24 + 10
-            ASSERT_TRUE(reader.ReadData(*op, &sink));
-            ASSERT_EQ(sink.stream(), xor_data);
+            ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+            ASSERT_EQ(sink, xor_data);
         }
 
         if (op->type == kCowReplaceOp) {
             total_blocks += 1;
             if (op->new_block == 100) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
                 data.resize(options.block_size);
-                ASSERT_EQ(sink.stream(), data);
+                std::string sink(data.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink.size(), data.size());
+                ASSERT_EQ(sink, data);
             }
             if (op->new_block == 6000) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
                 data2.resize(options.block_size);
-                ASSERT_EQ(sink.stream(), data2);
+                std::string sink(data2.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink, data2);
             }
             if (op->new_block == 9000) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
-                ASSERT_EQ(sink.stream(), data3);
+                std::string sink(data3.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink, data3);
             }
         }
 
@@ -376,7 +368,7 @@
     ASSERT_EQ(total_blocks, expected_blocks);
 }
 
-TEST_P(CompressionRWTest, NoBatchWrites) {
+TEST_P(CompressionTest, NoBatchWrites) {
     CowOptions options;
     options.compression = GetParam();
     options.num_compress_threads = 1;
@@ -410,27 +402,27 @@
     ASSERT_NE(iter, nullptr);
 
     int total_blocks = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         auto op = &iter->Get();
 
         if (op->type == kCowReplaceOp) {
             total_blocks += 1;
             if (op->new_block == 50) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
                 data.resize(options.block_size);
-                ASSERT_EQ(sink.stream(), data);
+                std::string sink(data.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink, data);
             }
             if (op->new_block == 3000) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
                 data2.resize(options.block_size);
-                ASSERT_EQ(sink.stream(), data2);
+                std::string sink(data2.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink, data2);
             }
             if (op->new_block == 5000) {
-                StringSink sink;
-                ASSERT_TRUE(reader.ReadData(*op, &sink));
-                ASSERT_EQ(sink.stream(), data3);
+                std::string sink(data3.size(), '\0');
+                ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+                ASSERT_EQ(sink, data3);
             }
         }
 
@@ -440,7 +432,66 @@
     ASSERT_EQ(total_blocks, expected_blocks);
 }
 
-INSTANTIATE_TEST_SUITE_P(CowApi, CompressionRWTest, testing::Values("none", "gz", "brotli", "lz4"));
+template <typename T>
+class HorribleStream : public IByteStream {
+  public:
+    HorribleStream(const std::basic_string<T>& input) : input_(input) {}
+
+    ssize_t Read(void* buffer, size_t length) override {
+        if (pos_ >= input_.size()) {
+            return 0;
+        }
+        if (length) {
+            *reinterpret_cast<char*>(buffer) = input_[pos_];
+        }
+        pos_++;
+        return 1;
+    }
+    size_t Size() const override { return input_.size(); }
+
+  private:
+    std::basic_string<T> input_;
+    size_t pos_ = 0;
+};
+
+TEST(HorribleStream, ReadFully) {
+    std::string expected = "this is some data";
+
+    HorribleStream<char> stream(expected);
+
+    std::string buffer(expected.size(), '\0');
+    ASSERT_TRUE(stream.ReadFully(buffer.data(), buffer.size()));
+    ASSERT_EQ(buffer, expected);
+}
+
+TEST_P(CompressionTest, HorribleStream) {
+    if (strcmp(GetParam(), "none") == 0) {
+        GTEST_SKIP();
+    }
+
+    auto algorithm = CompressionAlgorithmFromString(GetParam());
+    ASSERT_TRUE(algorithm.has_value());
+
+    std::string expected = "The quick brown fox jumps over the lazy dog.";
+    expected.resize(4096, '\0');
+
+    auto result = CompressWorker::Compress(*algorithm, expected.data(), expected.size());
+    ASSERT_FALSE(result.empty());
+
+    HorribleStream<uint8_t> stream(result);
+    auto decomp = IDecompressor::FromString(GetParam());
+    ASSERT_NE(decomp, nullptr);
+    decomp->set_stream(&stream);
+
+    expected = expected.substr(10, 500);
+
+    std::string buffer(expected.size(), '\0');
+    ASSERT_EQ(decomp->Decompress(buffer.data(), 500, 4096, 10), 500);
+    ASSERT_EQ(buffer, expected);
+}
+
+INSTANTIATE_TEST_SUITE_P(AllCompressors, CompressionTest,
+                         testing::Values("none", "gz", "brotli", "lz4"));
 
 TEST_F(CowTest, ClusterCompressGz) {
     CowOptions options;
@@ -467,43 +518,44 @@
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     ASSERT_EQ(op->type, kCowReplaceOp);
     ASSERT_EQ(op->compression, kCowCompressGz);
     ASSERT_EQ(op->data_length, 56);  // compressed!
     ASSERT_EQ(op->new_block, 50);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowClusterOp);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
-    sink.Reset();
+    sink = {};
+    sink.resize(data2.size(), '\0');
     ASSERT_EQ(op->compression, kCowCompressGz);
     ASSERT_EQ(op->data_length, 41);  // compressed!
     ASSERT_EQ(op->new_block, 51);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data2);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data2);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
 
     ASSERT_EQ(op->type, kCowClusterOp);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, CompressTwoBlocks) {
@@ -527,59 +579,19 @@
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
 
-    StringSink sink;
+    std::string sink(options.block_size, '\0');
 
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
     ASSERT_EQ(op->compression, kCowCompressGz);
     ASSERT_EQ(op->new_block, 51);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
 }
 
-// Only return 1-byte buffers, to stress test the partial read logic in
-// CowReader.
-class HorribleStringSink : public StringSink {
-  public:
-    void* GetBuffer(size_t, size_t* actual) override { return StringSink::GetBuffer(1, actual); }
-};
-
-class CompressionTest : public CowTest, public testing::WithParamInterface<const char*> {};
-
-TEST_P(CompressionTest, HorribleSink) {
-    CowOptions options;
-    options.compression = GetParam();
-    options.cluster_ops = 0;
-    CowWriter writer(options);
-
-    ASSERT_TRUE(writer.Initialize(cow_->fd));
-
-    std::string data = "This is some data, believe it";
-    data.resize(options.block_size, '\0');
-
-    ASSERT_TRUE(writer.AddRawBlocks(50, data.data(), data.size()));
-    ASSERT_TRUE(writer.Finalize());
-
-    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
-
-    CowReader reader;
-    ASSERT_TRUE(reader.Parse(cow_->fd));
-
-    auto iter = reader.GetOpIter();
-    ASSERT_NE(iter, nullptr);
-    ASSERT_FALSE(iter->Done());
-
-    HorribleStringSink sink;
-    auto op = &iter->Get();
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
-}
-
-INSTANTIATE_TEST_SUITE_P(CowApi, CompressionTest, testing::Values("none", "gz", "brotli"));
-
 TEST_F(CowTest, GetSize) {
     CowOptions options;
     options.cluster_ops = 0;
@@ -641,35 +653,36 @@
     ASSERT_TRUE(reader.GetLastLabel(&label));
     ASSERT_EQ(label, 3);
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data);
 
     iter->Next();
-    sink.Reset();
+    sink = {};
+    sink.resize(data2.size(), '\0');
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 3);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data2);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data2);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, AppendLabelMissing) {
@@ -705,25 +718,23 @@
     CowReader reader;
     ASSERT_TRUE(reader.Parse(cow_->fd));
 
-    StringSink sink;
-
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 0);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowZeroOp);
 
     iter->Next();
 
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, AppendExtendedCorrupted) {
@@ -765,18 +776,16 @@
     CowReader reader;
     ASSERT_TRUE(reader.Parse(cow_->fd));
 
-    StringSink sink;
-
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 5);
 
     iter->Next();
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, AppendbyLabel) {
@@ -816,55 +825,55 @@
     CowReader reader;
     ASSERT_TRUE(reader.Parse(cow_->fd));
 
-    StringSink sink;
+    std::string sink(options.block_size, '\0');
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data.substr(0, options.block_size));
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data.substr(0, options.block_size));
 
     iter->Next();
-    sink.Reset();
+    sink = {};
+    sink.resize(options.block_size, '\0');
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data.substr(options.block_size, 2 * options.block_size));
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data.substr(options.block_size, 2 * options.block_size));
 
     iter->Next();
-    sink.Reset();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 4);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowZeroOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowZeroOp);
 
     iter->Next();
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 5);
 
     iter->Next();
 
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, ClusterTest) {
@@ -897,72 +906,71 @@
     CowReader reader;
     ASSERT_TRUE(reader.Parse(cow_->fd));
 
-    StringSink sink;
+    std::string sink(data.size(), '\0');
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data.substr(0, options.block_size));
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data.substr(0, options.block_size));
 
     iter->Next();
-    sink.Reset();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 4);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowZeroOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowClusterOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowZeroOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 5);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowCopyOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowClusterOp);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 6);
 
     iter->Next();
 
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, ClusterAppendTest) {
@@ -997,33 +1005,33 @@
     ASSERT_TRUE(reader.GetLastLabel(&label));
     ASSERT_EQ(label, 50);
 
-    StringSink sink;
+    std::string sink(data2.size(), '\0');
 
     auto iter = reader.GetOpIter();
     ASSERT_NE(iter, nullptr);
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     auto op = &iter->Get();
     ASSERT_EQ(op->type, kCowLabelOp);
     ASSERT_EQ(op->source, 50);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowReplaceOp);
-    ASSERT_TRUE(reader.ReadData(*op, &sink));
-    ASSERT_EQ(sink.stream(), data2);
+    ASSERT_TRUE(ReadData(reader, *op, sink.data(), sink.size()));
+    ASSERT_EQ(sink, data2);
 
     iter->Next();
 
-    ASSERT_FALSE(iter->Done());
+    ASSERT_FALSE(iter->AtEnd());
     op = &iter->Get();
     ASSERT_EQ(op->type, kCowClusterOp);
 
     iter->Next();
 
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, AppendAfterFinalize) {
@@ -1060,19 +1068,18 @@
 
 AssertionResult CompareDataBlock(CowReader* reader, const CowOperation& op,
                                  const std::string& data) {
-    CowHeader header;
-    reader->GetHeader(&header);
+    const auto& header = reader->GetHeader();
 
     std::string cmp = data;
     cmp.resize(header.block_size, '\0');
 
-    StringSink sink;
-    if (!reader->ReadData(op, &sink)) {
+    std::string sink(cmp.size(), '\0');
+    if (!reader->ReadData(op, sink.data(), sink.size())) {
         return AssertionFailure() << "Failed to read data block";
     }
-    if (cmp != sink.stream()) {
+    if (cmp != sink) {
         return AssertionFailure() << "Data blocks did not match, expected " << cmp << ", got "
-                                  << sink.stream();
+                                  << sink;
     }
 
     return AssertionSuccess();
@@ -1111,7 +1118,7 @@
     size_t max_in_cluster = 0;
     size_t num_in_cluster = 0;
     size_t num_clusters = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         const auto& op = iter->Get();
 
         num_in_cluster++;
@@ -1172,7 +1179,7 @@
     size_t max_in_cluster = 0;
     size_t num_in_cluster = 0;
     size_t num_clusters = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         const auto& op = iter->Get();
 
         num_in_cluster++;
@@ -1224,7 +1231,7 @@
     size_t max_in_cluster = 0;
     size_t num_in_cluster = 0;
     size_t num_clusters = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         const auto& op = iter->Get();
 
         num_in_cluster++;
@@ -1268,14 +1275,14 @@
     auto iter = reader.GetRevMergeOpIter();
 
     for (int i = 0; i < seq_len; i++) {
-        ASSERT_TRUE(!iter->Done());
+        ASSERT_TRUE(!iter->AtEnd());
         const auto& op = iter->Get();
 
         ASSERT_EQ(op.new_block, seq_len - i);
 
         iter->Next();
     }
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, MissingSeqOp) {
@@ -1319,7 +1326,7 @@
     auto reader = std::make_unique<CowReader>();
     ASSERT_TRUE(reader->Parse(cow_->fd, 1));
     auto itr = reader->GetRevMergeOpIter();
-    ASSERT_TRUE(itr->Done());
+    ASSERT_TRUE(itr->AtEnd());
 
     writer = std::make_unique<CowWriter>(options);
     ASSERT_TRUE(writer->InitializeAppend(cow_->fd, 1));
@@ -1334,8 +1341,8 @@
     auto iter = reader->GetRevMergeOpIter();
 
     uint64_t expected_block = 10;
-    while (!iter->Done() && expected_block > 0) {
-        ASSERT_FALSE(iter->Done());
+    while (!iter->AtEnd() && expected_block > 0) {
+        ASSERT_FALSE(iter->AtEnd());
         const auto& op = iter->Get();
 
         ASSERT_EQ(op.new_block, expected_block);
@@ -1344,7 +1351,7 @@
         expected_block--;
     }
     ASSERT_EQ(expected_block, 0);
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, RevMergeOpItrTest) {
@@ -1385,7 +1392,7 @@
     auto iter = reader.GetRevMergeOpIter();
     auto expected_new_block = revMergeOpSequence.begin();
 
-    while (!iter->Done() && expected_new_block != revMergeOpSequence.end()) {
+    while (!iter->AtEnd() && expected_new_block != revMergeOpSequence.end()) {
         const auto& op = iter->Get();
 
         ASSERT_EQ(op.new_block, *expected_new_block);
@@ -1394,7 +1401,7 @@
         expected_new_block++;
     }
     ASSERT_EQ(expected_new_block, revMergeOpSequence.end());
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, LegacyRevMergeOpItrTest) {
@@ -1434,7 +1441,7 @@
     auto iter = reader.GetRevMergeOpIter();
     auto expected_new_block = revMergeOpSequence.begin();
 
-    while (!iter->Done() && expected_new_block != revMergeOpSequence.end()) {
+    while (!iter->AtEnd() && expected_new_block != revMergeOpSequence.end()) {
         const auto& op = iter->Get();
 
         ASSERT_EQ(op.new_block, *expected_new_block);
@@ -1443,7 +1450,7 @@
         expected_new_block++;
     }
     ASSERT_EQ(expected_new_block, revMergeOpSequence.end());
-    ASSERT_TRUE(iter->Done());
+    ASSERT_TRUE(iter->AtEnd());
 }
 
 TEST_F(CowTest, InvalidMergeOrderTest) {
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
index 9b50986..d06c904 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
@@ -32,6 +32,21 @@
 
 namespace android {
 namespace snapshot {
+
+std::optional<CowCompressionAlgorithm> CompressionAlgorithmFromString(std::string_view name) {
+    if (name == "gz") {
+        return {kCowCompressGz};
+    } else if (name == "brotli") {
+        return {kCowCompressBrotli};
+    } else if (name == "lz4") {
+        return {kCowCompressLz4};
+    } else if (name == "none" || name.empty()) {
+        return {kCowCompressNone};
+    } else {
+        return {};
+    }
+}
+
 std::basic_string<uint8_t> CompressWorker::Compress(const void* data, size_t length) {
     return Compress(compression_, data, length);
 }
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
index 139a29f..3d34413 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
@@ -16,6 +16,7 @@
 
 #include "cow_decompress.h"
 
+#include <array>
 #include <utility>
 
 #include <android-base/logging.h>
@@ -26,114 +27,108 @@
 namespace android {
 namespace snapshot {
 
-class NoDecompressor final : public IDecompressor {
-  public:
-    bool Decompress(size_t) override;
-};
+ssize_t IByteStream::ReadFully(void* buffer, size_t buffer_size) {
+    size_t stream_remaining = Size();
 
-bool NoDecompressor::Decompress(size_t) {
-    size_t stream_remaining = stream_->Size();
+    char* buffer_start = reinterpret_cast<char*>(buffer);
+    char* buffer_pos = buffer_start;
+    size_t buffer_remaining = buffer_size;
     while (stream_remaining) {
-        size_t buffer_size = stream_remaining;
-        uint8_t* buffer = reinterpret_cast<uint8_t*>(sink_->GetBuffer(buffer_size, &buffer_size));
-        if (!buffer) {
-            LOG(ERROR) << "Could not acquire buffer from sink";
-            return false;
+        const size_t to_read = std::min(buffer_remaining, stream_remaining);
+        const ssize_t actual_read = Read(buffer_pos, to_read);
+        if (actual_read < 0) {
+            return -1;
         }
+        if (!actual_read) {
+            LOG(ERROR) << "Stream ended prematurely";
+            return -1;
+        }
+        CHECK_LE(actual_read, to_read);
 
-        // Read until we can fill the buffer.
-        uint8_t* buffer_pos = buffer;
-        size_t bytes_to_read = std::min(buffer_size, stream_remaining);
-        while (bytes_to_read) {
-            size_t read;
-            if (!stream_->Read(buffer_pos, bytes_to_read, &read)) {
-                return false;
-            }
-            if (!read) {
-                LOG(ERROR) << "Stream ended prematurely";
-                return false;
-            }
-            if (!sink_->ReturnData(buffer_pos, read)) {
-                LOG(ERROR) << "Could not return buffer to sink";
-                return false;
-            }
-            buffer_pos += read;
-            bytes_to_read -= read;
-            stream_remaining -= read;
-        }
+        stream_remaining -= actual_read;
+        buffer_pos += actual_read;
+        buffer_remaining -= actual_read;
     }
-    return true;
+    return buffer_pos - buffer_start;
 }
 
-std::unique_ptr<IDecompressor> IDecompressor::Uncompressed() {
-    return std::unique_ptr<IDecompressor>(new NoDecompressor());
+std::unique_ptr<IDecompressor> IDecompressor::FromString(std::string_view compressor) {
+    if (compressor == "lz4") {
+        return IDecompressor::Lz4();
+    } else if (compressor == "brotli") {
+        return IDecompressor::Brotli();
+    } else if (compressor == "gz") {
+        return IDecompressor::Gz();
+    } else {
+        return nullptr;
+    }
 }
 
 // Read chunks of the COW and incrementally stream them to the decoder.
 class StreamDecompressor : public IDecompressor {
   public:
-    bool Decompress(size_t output_bytes) override;
+    ssize_t Decompress(void* buffer, size_t buffer_size, size_t decompressed_size,
+                       size_t ignore_bytes) override;
 
     virtual bool Init() = 0;
-    virtual bool DecompressInput(const uint8_t* data, size_t length) = 0;
-    virtual bool Done() = 0;
+    virtual bool PartialDecompress(const uint8_t* data, size_t length) = 0;
+    bool OutputFull() const { return !ignore_bytes_ && !output_buffer_remaining_; }
 
   protected:
-    bool GetFreshBuffer();
-
-    size_t output_bytes_;
     size_t stream_remaining_;
     uint8_t* output_buffer_ = nullptr;
     size_t output_buffer_remaining_ = 0;
+    size_t ignore_bytes_ = 0;
+    bool decompressor_ended_ = false;
 };
 
 static constexpr size_t kChunkSize = 4096;
 
-bool StreamDecompressor::Decompress(size_t output_bytes) {
+ssize_t StreamDecompressor::Decompress(void* buffer, size_t buffer_size, size_t,
+                                       size_t ignore_bytes) {
     if (!Init()) {
         return false;
     }
 
     stream_remaining_ = stream_->Size();
-    output_bytes_ = output_bytes;
+    output_buffer_ = reinterpret_cast<uint8_t*>(buffer);
+    output_buffer_remaining_ = buffer_size;
+    ignore_bytes_ = ignore_bytes;
 
     uint8_t chunk[kChunkSize];
-    while (stream_remaining_) {
-        size_t read = std::min(stream_remaining_, sizeof(chunk));
-        if (!stream_->Read(chunk, read, &read)) {
-            return false;
+    while (stream_remaining_ && output_buffer_remaining_ && !decompressor_ended_) {
+        size_t max_read = std::min(stream_remaining_, sizeof(chunk));
+        ssize_t read = stream_->Read(chunk, max_read);
+        if (read < 0) {
+            return -1;
         }
         if (!read) {
             LOG(ERROR) << "Stream ended prematurely";
-            return false;
+            return -1;
         }
-        if (!DecompressInput(chunk, read)) {
-            return false;
+        if (!PartialDecompress(chunk, read)) {
+            return -1;
         }
-
         stream_remaining_ -= read;
+    }
 
-        if (stream_remaining_ && Done()) {
+    if (stream_remaining_) {
+        if (decompressor_ended_ && !OutputFull()) {
+            // If there's more input in the stream, but we haven't finished
+            // consuming ignored bytes or available output space yet, then
+            // something weird happened. Report it and fail.
             LOG(ERROR) << "Decompressor terminated early";
-            return false;
+            return -1;
+        }
+    } else {
+        if (!decompressor_ended_ && !OutputFull()) {
+            // The stream ended, but the decoder doesn't think so, and there are
+            // more bytes in the output buffer.
+            LOG(ERROR) << "Decompressor expected more bytes";
+            return -1;
         }
     }
-    if (!Done()) {
-        LOG(ERROR) << "Decompressor expected more bytes";
-        return false;
-    }
-    return true;
-}
-
-bool StreamDecompressor::GetFreshBuffer() {
-    size_t request_size = std::min(output_bytes_, kChunkSize);
-    output_buffer_ =
-            reinterpret_cast<uint8_t*>(sink_->GetBuffer(request_size, &output_buffer_remaining_));
-    if (!output_buffer_) {
-        LOG(ERROR) << "Could not acquire buffer from sink";
-        return false;
-    }
-    return true;
+    return buffer_size - output_buffer_remaining_;
 }
 
 class GzDecompressor final : public StreamDecompressor {
@@ -141,12 +136,10 @@
     ~GzDecompressor();
 
     bool Init() override;
-    bool DecompressInput(const uint8_t* data, size_t length) override;
-    bool Done() override { return ended_; }
+    bool PartialDecompress(const uint8_t* data, size_t length) override;
 
   private:
     z_stream z_ = {};
-    bool ended_ = false;
 };
 
 bool GzDecompressor::Init() {
@@ -161,23 +154,39 @@
     inflateEnd(&z_);
 }
 
-bool GzDecompressor::DecompressInput(const uint8_t* data, size_t length) {
+bool GzDecompressor::PartialDecompress(const uint8_t* data, size_t length) {
     z_.next_in = reinterpret_cast<Bytef*>(const_cast<uint8_t*>(data));
     z_.avail_in = length;
 
-    while (z_.avail_in) {
-        // If no more output buffer, grab a new buffer.
-        if (z_.avail_out == 0) {
-            if (!GetFreshBuffer()) {
-                return false;
-            }
-            z_.next_out = reinterpret_cast<Bytef*>(output_buffer_);
-            z_.avail_out = output_buffer_remaining_;
+    // If we're asked to ignore starting bytes, we sink those into the output
+    // repeatedly until there is nothing left to ignore.
+    while (ignore_bytes_ && z_.avail_in) {
+        std::array<Bytef, kChunkSize> ignore_buffer;
+        size_t max_ignore = std::min(ignore_bytes_, ignore_buffer.size());
+        z_.next_out = ignore_buffer.data();
+        z_.avail_out = max_ignore;
+
+        int rv = inflate(&z_, Z_NO_FLUSH);
+        if (rv != Z_OK && rv != Z_STREAM_END) {
+            LOG(ERROR) << "inflate returned error code " << rv;
+            return false;
         }
 
-        // Remember the position of the output buffer so we can call ReturnData.
-        auto avail_out = z_.avail_out;
+        size_t returned = max_ignore - z_.avail_out;
+        CHECK_LE(returned, ignore_bytes_);
 
+        ignore_bytes_ -= returned;
+
+        if (rv == Z_STREAM_END) {
+            decompressor_ended_ = true;
+            return true;
+        }
+    }
+
+    z_.next_out = reinterpret_cast<Bytef*>(output_buffer_);
+    z_.avail_out = output_buffer_remaining_;
+
+    while (z_.avail_in && z_.avail_out) {
         // Decompress.
         int rv = inflate(&z_, Z_NO_FLUSH);
         if (rv != Z_OK && rv != Z_STREAM_END) {
@@ -185,20 +194,14 @@
             return false;
         }
 
-        size_t returned = avail_out - z_.avail_out;
-        if (!sink_->ReturnData(output_buffer_, returned)) {
-            LOG(ERROR) << "Could not return buffer to sink";
-            return false;
-        }
+        size_t returned = output_buffer_remaining_ - z_.avail_out;
+        CHECK_LE(returned, output_buffer_remaining_);
+
         output_buffer_ += returned;
         output_buffer_remaining_ -= returned;
 
         if (rv == Z_STREAM_END) {
-            if (z_.avail_in) {
-                LOG(ERROR) << "Gz stream ended prematurely";
-                return false;
-            }
-            ended_ = true;
+            decompressor_ended_ = true;
             return true;
         }
     }
@@ -214,8 +217,7 @@
     ~BrotliDecompressor();
 
     bool Init() override;
-    bool DecompressInput(const uint8_t* data, size_t length) override;
-    bool Done() override { return BrotliDecoderIsFinished(decoder_); }
+    bool PartialDecompress(const uint8_t* data, size_t length) override;
 
   private:
     BrotliDecoderState* decoder_ = nullptr;
@@ -232,28 +234,41 @@
     }
 }
 
-bool BrotliDecompressor::DecompressInput(const uint8_t* data, size_t length) {
+bool BrotliDecompressor::PartialDecompress(const uint8_t* data, size_t length) {
     size_t available_in = length;
     const uint8_t* next_in = data;
 
-    bool needs_more_output = false;
-    while (available_in || needs_more_output) {
-        if (!output_buffer_remaining_ && !GetFreshBuffer()) {
+    while (available_in && ignore_bytes_ && !BrotliDecoderIsFinished(decoder_)) {
+        std::array<uint8_t, kChunkSize> ignore_buffer;
+        size_t max_ignore = std::min(ignore_bytes_, ignore_buffer.size());
+        size_t ignore_size = max_ignore;
+
+        uint8_t* ignore_buffer_ptr = ignore_buffer.data();
+        auto r = BrotliDecoderDecompressStream(decoder_, &available_in, &next_in, &ignore_size,
+                                               &ignore_buffer_ptr, nullptr);
+        if (r == BROTLI_DECODER_RESULT_ERROR) {
+            LOG(ERROR) << "brotli decode failed";
+            return false;
+        } else if (r == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT && available_in) {
+            LOG(ERROR) << "brotli unexpected needs more input";
             return false;
         }
+        ignore_bytes_ -= max_ignore - ignore_size;
+    }
 
-        auto output_buffer = output_buffer_;
+    while (available_in && !BrotliDecoderIsFinished(decoder_)) {
         auto r = BrotliDecoderDecompressStream(decoder_, &available_in, &next_in,
                                                &output_buffer_remaining_, &output_buffer_, nullptr);
         if (r == BROTLI_DECODER_RESULT_ERROR) {
             LOG(ERROR) << "brotli decode failed";
             return false;
-        }
-        if (!sink_->ReturnData(output_buffer, output_buffer_ - output_buffer)) {
+        } else if (r == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT && available_in) {
+            LOG(ERROR) << "brotli unexpected needs more input";
             return false;
         }
-        needs_more_output = (r == BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT);
     }
+
+    decompressor_ended_ = BrotliDecoderIsFinished(decoder_);
     return true;
 }
 
@@ -265,45 +280,59 @@
   public:
     ~Lz4Decompressor() override = default;
 
-    bool Decompress(const size_t output_size) override {
-        size_t actual_buffer_size = 0;
-        auto&& output_buffer = sink_->GetBuffer(output_size, &actual_buffer_size);
-        if (actual_buffer_size != output_size) {
-            LOG(ERROR) << "Failed to allocate buffer of size " << output_size << " only got "
-                       << actual_buffer_size << " bytes";
-            return false;
+    ssize_t Decompress(void* buffer, size_t buffer_size, size_t decompressed_size,
+                       size_t ignore_bytes) override {
+        std::string input_buffer(stream_->Size(), '\0');
+        ssize_t streamed_in = stream_->ReadFully(input_buffer.data(), input_buffer.size());
+        if (streamed_in < 0) {
+            return -1;
         }
-        // If input size is same as output size, then input is uncompressed.
-        if (stream_->Size() == output_size) {
-            size_t bytes_read = 0;
-            stream_->Read(output_buffer, output_size, &bytes_read);
-            if (bytes_read != output_size) {
-                LOG(ERROR) << "Failed to read all input at once. Expected: " << output_size
-                           << " actual: " << bytes_read;
-                return false;
+        CHECK_EQ(streamed_in, stream_->Size());
+
+        char* decode_buffer = reinterpret_cast<char*>(buffer);
+        size_t decode_buffer_size = buffer_size;
+
+        // It's unclear if LZ4 can exactly satisfy a partial decode request, so
+        // if we get one, create a temporary buffer.
+        std::string temp;
+        if (buffer_size < decompressed_size) {
+            temp.resize(decompressed_size, '\0');
+            decode_buffer = temp.data();
+            decode_buffer_size = temp.size();
+        }
+
+        const int bytes_decompressed = LZ4_decompress_safe(input_buffer.data(), decode_buffer,
+                                                           input_buffer.size(), decode_buffer_size);
+        if (bytes_decompressed < 0) {
+            LOG(ERROR) << "Failed to decompress LZ4 block, code: " << bytes_decompressed;
+            return -1;
+        }
+        if (bytes_decompressed != decompressed_size) {
+            LOG(ERROR) << "Failed to decompress LZ4 block, expected output size: "
+                       << bytes_decompressed << ", actual: " << bytes_decompressed;
+            return -1;
+        }
+        CHECK_LE(bytes_decompressed, decode_buffer_size);
+
+        if (ignore_bytes > bytes_decompressed) {
+            LOG(ERROR) << "Ignoring more bytes than exist in stream (ignoring " << ignore_bytes
+                       << ", got " << bytes_decompressed << ")";
+            return -1;
+        }
+
+        if (temp.empty()) {
+            // LZ4's API has no way to sink out the first N bytes of decoding,
+            // so we read them all in and memmove() to drop the partial read.
+            if (ignore_bytes) {
+                memmove(decode_buffer, decode_buffer + ignore_bytes,
+                        bytes_decompressed - ignore_bytes);
             }
-            sink_->ReturnData(output_buffer, output_size);
-            return true;
+            return bytes_decompressed - ignore_bytes;
         }
-        std::string input_buffer;
-        input_buffer.resize(stream_->Size());
-        size_t bytes_read = 0;
-        stream_->Read(input_buffer.data(), input_buffer.size(), &bytes_read);
-        if (bytes_read != input_buffer.size()) {
-            LOG(ERROR) << "Failed to read all input at once. Expected: " << input_buffer.size()
-                       << " actual: " << bytes_read;
-            return false;
-        }
-        const int bytes_decompressed =
-                LZ4_decompress_safe(input_buffer.data(), static_cast<char*>(output_buffer),
-                                    input_buffer.size(), output_size);
-        if (bytes_decompressed != output_size) {
-            LOG(ERROR) << "Failed to decompress LZ4 block, expected output size: " << output_size
-                       << ", actual: " << bytes_decompressed;
-            return false;
-        }
-        sink_->ReturnData(output_buffer, output_size);
-        return true;
+
+        size_t max_copy = std::min(bytes_decompressed - ignore_bytes, buffer_size);
+        memcpy(buffer, temp.data() + ignore_bytes, max_copy);
+        return max_copy;
     }
 };
 
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
index 7f74eda..9e83f3c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
@@ -26,11 +26,16 @@
     virtual ~IByteStream() {}
 
     // Read up to |length| bytes, storing the number of bytes read in the out-
-    // parameter. If the end of the stream is reached, 0 is returned.
-    virtual bool Read(void* buffer, size_t length, size_t* read) = 0;
+    // parameter. If the end of the stream is reached, 0 is returned. On error,
+    // -1 is returned. errno is NOT set.
+    virtual ssize_t Read(void* buffer, size_t length) = 0;
 
     // Size of the stream.
     virtual size_t Size() const = 0;
+
+    // Helper for Read(). Read the entire stream into |buffer|, up to |length|
+    // bytes.
+    ssize_t ReadFully(void* buffer, size_t length);
 };
 
 class IDecompressor {
@@ -43,15 +48,22 @@
     static std::unique_ptr<IDecompressor> Brotli();
     static std::unique_ptr<IDecompressor> Lz4();
 
-    // |output_bytes| is the expected total number of bytes to sink.
-    virtual bool Decompress(size_t output_bytes) = 0;
+    static std::unique_ptr<IDecompressor> FromString(std::string_view compressor);
+
+    // Decompress at most |buffer_size| bytes, ignoring the first |ignore_bytes|
+    // of the decoded stream. |buffer_size| must be at least one byte.
+    // |decompressed_size| is the expected total size if the entire stream were
+    // decompressed.
+    //
+    // Returns the number of bytes written to |buffer|, or -1 on error. errno
+    // is NOT set.
+    virtual ssize_t Decompress(void* buffer, size_t buffer_size, size_t decompressed_size,
+                               size_t ignore_bytes = 0) = 0;
 
     void set_stream(IByteStream* stream) { stream_ = stream; }
-    void set_sink(IByteSink* sink) { sink_ = sink; }
 
   protected:
     IByteStream* stream_ = nullptr;
-    IByteSink* sink_ = nullptr;
 };
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 45be191..893d95f 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -509,7 +509,7 @@
 bool CowReader::VerifyMergeOps() {
     auto itr = GetMergeOpIter(true);
     std::unordered_map<uint64_t, CowOperation> overwritten_blocks;
-    while (!itr->Done()) {
+    while (!itr->AtEnd()) {
         CowOperation op = itr->Get();
         uint64_t block;
         bool offset;
@@ -544,11 +544,6 @@
     return true;
 }
 
-bool CowReader::GetHeader(CowHeader* header) {
-    *header = header_;
-    return true;
-}
-
 bool CowReader::GetFooter(CowFooter* footer) {
     if (!footer_) return false;
     *footer = footer_.value();
@@ -565,12 +560,12 @@
   public:
     CowOpIter(std::shared_ptr<std::vector<CowOperation>>& ops, uint64_t start);
 
-    bool Done() override;
+    bool AtEnd() override;
     const CowOperation& Get() override;
     void Next() override;
 
     void Prev() override;
-    bool RDone() override;
+    bool AtBegin() override;
 
   private:
     std::shared_ptr<std::vector<CowOperation>> ops_;
@@ -582,26 +577,26 @@
     op_iter_ = ops_->begin() + start;
 }
 
-bool CowOpIter::RDone() {
+bool CowOpIter::AtBegin() {
     return op_iter_ == ops_->begin();
 }
 
 void CowOpIter::Prev() {
-    CHECK(!RDone());
+    CHECK(!AtBegin());
     op_iter_--;
 }
 
-bool CowOpIter::Done() {
+bool CowOpIter::AtEnd() {
     return op_iter_ == ops_->end();
 }
 
 void CowOpIter::Next() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     op_iter_++;
 }
 
 const CowOperation& CowOpIter::Get() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     return (*op_iter_);
 }
 
@@ -610,12 +605,12 @@
     explicit CowRevMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops,
                                std::shared_ptr<std::vector<int>> block_pos_index, uint64_t start);
 
-    bool Done() override;
+    bool AtEnd() override;
     const CowOperation& Get() override;
     void Next() override;
 
     void Prev() override;
-    bool RDone() override;
+    bool AtBegin() override;
 
   private:
     std::shared_ptr<std::vector<CowOperation>> ops_;
@@ -629,12 +624,12 @@
     explicit CowMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops,
                             std::shared_ptr<std::vector<int>> block_pos_index, uint64_t start);
 
-    bool Done() override;
+    bool AtEnd() override;
     const CowOperation& Get() override;
     void Next() override;
 
     void Prev() override;
-    bool RDone() override;
+    bool AtBegin() override;
 
   private:
     std::shared_ptr<std::vector<CowOperation>> ops_;
@@ -651,26 +646,26 @@
     block_iter_ = cow_op_index_vec_->begin() + start;
 }
 
-bool CowMergeOpIter::RDone() {
+bool CowMergeOpIter::AtBegin() {
     return block_iter_ == cow_op_index_vec_->begin();
 }
 
 void CowMergeOpIter::Prev() {
-    CHECK(!RDone());
+    CHECK(!AtBegin());
     block_iter_--;
 }
 
-bool CowMergeOpIter::Done() {
+bool CowMergeOpIter::AtEnd() {
     return block_iter_ == cow_op_index_vec_->end();
 }
 
 void CowMergeOpIter::Next() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     block_iter_++;
 }
 
 const CowOperation& CowMergeOpIter::Get() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     return ops_->data()[*block_iter_];
 }
 
@@ -683,26 +678,26 @@
     block_riter_ = cow_op_index_vec_->rbegin();
 }
 
-bool CowRevMergeOpIter::RDone() {
+bool CowRevMergeOpIter::AtBegin() {
     return block_riter_ == cow_op_index_vec_->rbegin();
 }
 
 void CowRevMergeOpIter::Prev() {
-    CHECK(!RDone());
+    CHECK(!AtBegin());
     block_riter_--;
 }
 
-bool CowRevMergeOpIter::Done() {
+bool CowRevMergeOpIter::AtEnd() {
     return block_riter_ == cow_op_index_vec_->rend() - start_;
 }
 
 void CowRevMergeOpIter::Next() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     block_riter_++;
 }
 
 const CowOperation& CowRevMergeOpIter::Get() {
-    CHECK(!Done());
+    CHECK(!AtEnd());
     return ops_->data()[*block_riter_];
 }
 
@@ -747,18 +742,18 @@
         remaining_ = data_length_;
     }
 
-    bool Read(void* buffer, size_t length, size_t* read) override {
+    ssize_t Read(void* buffer, size_t length) override {
         size_t to_read = std::min(length, remaining_);
         if (!to_read) {
-            *read = 0;
-            return true;
+            return 0;
         }
-        if (!reader_->GetRawBytes(offset_, buffer, to_read, read)) {
-            return false;
+        size_t read;
+        if (!reader_->GetRawBytes(offset_, buffer, to_read, &read)) {
+            return -1;
         }
-        offset_ += *read;
-        remaining_ -= *read;
-        return true;
+        offset_ += read;
+        remaining_ -= read;
+        return read;
     }
 
     size_t Size() const override { return data_length_; }
@@ -770,11 +765,11 @@
     size_t remaining_;
 };
 
-bool CowReader::ReadData(const CowOperation& op, IByteSink* sink) {
+ssize_t CowReader::ReadData(const CowOperation& op, void* buffer, size_t buffer_size,
+                            size_t ignore_bytes) {
     std::unique_ptr<IDecompressor> decompressor;
     switch (op.compression) {
         case kCowCompressNone:
-            decompressor = IDecompressor::Uncompressed();
             break;
         case kCowCompressGz:
             decompressor = IDecompressor::Gz();
@@ -783,11 +778,13 @@
             decompressor = IDecompressor::Brotli();
             break;
         case kCowCompressLz4:
-            decompressor = IDecompressor::Lz4();
+            if (header_.block_size != op.data_length) {
+                decompressor = IDecompressor::Lz4();
+            }
             break;
         default:
             LOG(ERROR) << "Unknown compression type: " << op.compression;
-            return false;
+            return -1;
     }
 
     uint64_t offset;
@@ -796,10 +793,15 @@
     } else {
         offset = op.source;
     }
+
+    if (!decompressor) {
+        CowDataStream stream(this, offset + ignore_bytes, op.data_length - ignore_bytes);
+        return stream.ReadFully(buffer, buffer_size);
+    }
+
     CowDataStream stream(this, offset, op.data_length);
     decompressor->set_stream(&stream);
-    decompressor->set_sink(sink);
-    return decompressor->Decompress(header_.block_size);
+    return decompressor->Decompress(buffer, buffer_size, header_.block_size, ignore_bytes);
 }
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
index 56b48f0..cb20c6f 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
@@ -37,6 +37,14 @@
 #include <sys/ioctl.h>
 #include <unistd.h>
 
+// The info messages here are spammy, but as useful for update_engine. Disable
+// them when running on the host.
+#ifdef __ANDROID__
+#define LOG_INFO LOG(INFO)
+#else
+#define LOG_INFO LOG(VERBOSE)
+#endif
+
 namespace android {
 namespace snapshot {
 
@@ -194,18 +202,13 @@
 }
 
 bool CowWriter::ParseOptions() {
-    if (options_.compression == "gz") {
-        compression_ = kCowCompressGz;
-    } else if (options_.compression == "brotli") {
-        compression_ = kCowCompressBrotli;
-    } else if (options_.compression == "lz4") {
-        compression_ = kCowCompressLz4;
-    } else if (options_.compression == "none") {
-        compression_ = kCowCompressNone;
-    } else if (!options_.compression.empty()) {
+    auto algorithm = CompressionAlgorithmFromString(options_.compression);
+    if (!algorithm) {
         LOG(ERROR) << "unrecognized compression: " << options_.compression;
         return false;
     }
+    compression_ = *algorithm;
+
     if (options_.cluster_ops == 1) {
         LOG(ERROR) << "Clusters must contain at least two operations to function.";
         return false;
@@ -239,10 +242,10 @@
                 return false;
             }
             cow_image_size_ = size_in_bytes;
-            LOG(INFO) << "COW image " << file_path << " has size " << size_in_bytes;
+            LOG_INFO << "COW image " << file_path << " has size " << size_in_bytes;
         } else {
-            LOG(INFO) << "COW image " << file_path
-                      << " is not a block device, assuming unlimited space.";
+            LOG_INFO << "COW image " << file_path
+                     << " is not a block device, assuming unlimited space.";
         }
     }
     return true;
@@ -271,12 +274,12 @@
     }
 
     std::string batch_write = batch_write_ ? "enabled" : "disabled";
-    LOG(INFO) << "Batch writes: " << batch_write;
+    LOG_INFO << "Batch writes: " << batch_write;
 }
 
 void CowWriter::InitWorkers() {
     if (num_compress_threads_ <= 1) {
-        LOG(INFO) << "Not creating new threads for compression.";
+        LOG_INFO << "Not creating new threads for compression.";
         return;
     }
     for (int i = 0; i < num_compress_threads_; i++) {
@@ -285,7 +288,7 @@
         compress_threads_.push_back(std::move(wt));
     }
 
-    LOG(INFO) << num_compress_threads_ << " thread used for compression";
+    LOG_INFO << num_compress_threads_ << " thread used for compression";
 }
 
 bool CowWriter::Initialize(unique_fd&& fd) {
@@ -389,10 +392,11 @@
     auto reader = std::make_unique<CowReader>();
     std::queue<CowOperation> toAdd;
 
-    if (!reader->Parse(fd_, {label}) || !reader->GetHeader(&header_)) {
+    if (!reader->Parse(fd_, {label})) {
         return false;
     }
 
+    header_ = reader->GetHeader();
     options_.block_size = header_.block_size;
     options_.cluster_ops = header_.cluster_ops;
 
@@ -402,7 +406,7 @@
 
     auto iter = reader->GetOpIter();
 
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         AddOperation(iter->Get());
         iter->Next();
     }
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
index 167ff8c..4090162 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
@@ -16,6 +16,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
+#include <chrono>
 #include <iomanip>
 #include <iostream>
 #include <string>
@@ -38,16 +39,16 @@
 }
 
 static void usage(void) {
-    LOG(ERROR) << "Usage: inspect_cow [-sd] <COW_FILE>";
-    LOG(ERROR) << "\t -s Run Silent";
-    LOG(ERROR) << "\t -d Attempt to decompress";
-    LOG(ERROR) << "\t -b Show data for failed decompress";
-    LOG(ERROR) << "\t -l Show ops";
-    LOG(ERROR) << "\t -m Show ops in reverse merge order";
-    LOG(ERROR) << "\t -n Show ops in merge order";
-    LOG(ERROR) << "\t -a Include merged ops in any merge order listing";
-    LOG(ERROR) << "\t -o Shows sequence op block order";
-    LOG(ERROR) << "\t -v Verifies merge order has no conflicts\n";
+    std::cerr << "Usage: inspect_cow [-sd] <COW_FILE>\n";
+    std::cerr << "\t -s Run Silent\n";
+    std::cerr << "\t -d Attempt to decompress\n";
+    std::cerr << "\t -b Show data for failed decompress\n";
+    std::cerr << "\t -l Show ops\n";
+    std::cerr << "\t -m Show ops in reverse merge order\n";
+    std::cerr << "\t -n Show ops in merge order\n";
+    std::cerr << "\t -a Include merged ops in any merge order listing\n";
+    std::cerr << "\t -o Shows sequence op block order\n";
+    std::cerr << "\t -v Verifies merge order has no conflicts\n";
 }
 
 enum OpIter { Normal, RevMerge, Merge };
@@ -63,24 +64,6 @@
     bool include_merged;
 };
 
-// Sink that always appends to the end of a string.
-class StringSink : public IByteSink {
-  public:
-    void* GetBuffer(size_t requested, size_t* actual) override {
-        size_t old_size = stream_.size();
-        stream_.resize(old_size + requested, '\0');
-        *actual = requested;
-        return stream_.data() + old_size;
-    }
-    bool ReturnData(void*, size_t) override { return true; }
-    void Reset() { stream_.clear(); }
-
-    std::string& stream() { return stream_; }
-
-  private:
-    std::string stream_;
-};
-
 static void ShowBad(CowReader& reader, const struct CowOperation& op) {
     size_t count;
     auto buffer = std::make_unique<uint8_t[]>(op.data_length);
@@ -107,37 +90,40 @@
     }
 
     CowReader reader;
+
+    auto start_time = std::chrono::steady_clock::now();
     if (!reader.Parse(fd)) {
         LOG(ERROR) << "parse failed: " << path;
         return false;
     }
+    std::chrono::duration<double> parse_time = std::chrono::steady_clock::now() - start_time;
 
-    CowHeader header;
-    if (!reader.GetHeader(&header)) {
-        LOG(ERROR) << "could not get header: " << path;
-        return false;
-    }
+    const CowHeader& header = reader.GetHeader();
     CowFooter footer;
     bool has_footer = false;
     if (reader.GetFooter(&footer)) has_footer = true;
 
     if (!opt.silent) {
-        std::cout << "Major version: " << header.major_version << "\n";
-        std::cout << "Minor version: " << header.minor_version << "\n";
+        std::cout << "Version: " << header.major_version << "." << header.minor_version << "\n";
         std::cout << "Header size: " << header.header_size << "\n";
         std::cout << "Footer size: " << header.footer_size << "\n";
         std::cout << "Block size: " << header.block_size << "\n";
-        std::cout << "Num merge ops: " << header.num_merge_ops << "\n";
-        std::cout << "RA buffer size: " << header.buffer_size << "\n";
-        std::cout << "\n";
+        std::cout << "Merge ops: " << header.num_merge_ops << "\n";
+        std::cout << "Readahead buffer: " << header.buffer_size << " bytes\n";
         if (has_footer) {
-            std::cout << "Total Ops size: " << footer.op.ops_size << "\n";
-            std::cout << "Number of Ops: " << footer.op.num_ops << "\n";
-            std::cout << "\n";
+            std::cout << "Footer: ops usage: " << footer.op.ops_size << " bytes\n";
+            std::cout << "Footer: op count: " << footer.op.num_ops << "\n";
+        } else {
+            std::cout << "Footer: none\n";
         }
     }
 
+    if (!opt.silent) {
+        std::cout << "Parse time: " << (parse_time.count() * 1000) << "ms\n";
+    }
+
     if (opt.verify_sequence) {
+        std::cout << "\n";
         if (reader.VerifyMergeOps()) {
             std::cout << "\nMerge sequence is consistent.\n";
         } else {
@@ -153,21 +139,22 @@
     } else if (opt.iter_type == Merge) {
         iter = reader.GetMergeOpIter(opt.include_merged);
     }
-    StringSink sink;
+
+    std::string buffer(header.block_size, '\0');
+
     bool success = true;
     uint64_t xor_ops = 0, copy_ops = 0, replace_ops = 0, zero_ops = 0;
-    while (!iter->Done()) {
+    while (!iter->AtEnd()) {
         const CowOperation& op = iter->Get();
 
         if (!opt.silent && opt.show_ops) std::cout << op << "\n";
 
         if (opt.decompress && op.type == kCowReplaceOp && op.compression != kCowCompressNone) {
-            if (!reader.ReadData(op, &sink)) {
+            if (reader.ReadData(op, buffer.data(), buffer.size()) < 0) {
                 std::cerr << "Failed to decompress for :" << op << "\n";
                 success = false;
                 if (opt.show_bad) ShowBad(reader, op);
             }
-            sink.Reset();
         }
 
         if (op.type == kCowSequenceOp && opt.show_seq) {
@@ -203,9 +190,11 @@
 
     if (!opt.silent) {
         auto total_ops = replace_ops + zero_ops + copy_ops + xor_ops;
-        std::cout << "Total-data-ops: " << total_ops << "Replace-ops: " << replace_ops
-                  << " Zero-ops: " << zero_ops << " Copy-ops: " << copy_ops
-                  << " Xor_ops: " << xor_ops << std::endl;
+        std::cout << "Data ops: " << total_ops << "\n";
+        std::cout << "Replace ops: " << replace_ops << "\n";
+        std::cout << "Zero ops: " << zero_ops << "\n";
+        std::cout << "Copy ops: " << copy_ops << "\n";
+        std::cout << "Xor ops: " << xor_ops << "\n";
     }
 
     return success;
@@ -254,15 +243,17 @@
                 break;
             default:
                 android::snapshot::usage();
+                return 1;
         }
     }
-    android::base::InitLogging(argv, android::snapshot::MyLogger);
 
     if (argc < optind + 1) {
         android::snapshot::usage();
         return 1;
     }
 
+    android::base::InitLogging(argv, android::snapshot::MyLogger);
+
     if (!android::snapshot::Inspect(argv[optind], opt)) {
         return 1;
     }
diff --git a/fs_mgr/libsnapshot/snapshot_reader.cpp b/fs_mgr/libsnapshot/snapshot_reader.cpp
index 6546c2a..48efae0 100644
--- a/fs_mgr/libsnapshot/snapshot_reader.cpp
+++ b/fs_mgr/libsnapshot/snapshot_reader.cpp
@@ -80,15 +80,12 @@
 bool CompressedSnapshotReader::SetCow(std::unique_ptr<CowReader>&& cow) {
     cow_ = std::move(cow);
 
-    CowHeader header;
-    if (!cow_->GetHeader(&header)) {
-        return false;
-    }
+    const auto& header = cow_->GetHeader();
     block_size_ = header.block_size;
 
     // Populate the operation map.
     op_iter_ = cow_->GetOpIter();
-    while (!op_iter_->Done()) {
+    while (!op_iter_->AtEnd()) {
         const CowOperation* op = &op_iter_->Get();
         if (IsMetadataOp(*op)) {
             op_iter_->Next();
@@ -128,37 +125,6 @@
     return source_fd_;
 }
 
-class MemoryByteSink : public IByteSink {
-  public:
-    MemoryByteSink(void* buf, size_t count) {
-        buf_ = reinterpret_cast<uint8_t*>(buf);
-        pos_ = buf_;
-        end_ = buf_ + count;
-    }
-
-    void* GetBuffer(size_t requested, size_t* actual) override {
-        *actual = std::min(remaining(), requested);
-        if (!*actual) {
-            return nullptr;
-        }
-
-        uint8_t* start = pos_;
-        pos_ += *actual;
-        return start;
-    }
-
-    bool ReturnData(void*, size_t) override { return true; }
-
-    uint8_t* buf() const { return buf_; }
-    uint8_t* pos() const { return pos_; }
-    size_t remaining() const { return end_ - pos_; }
-
-  private:
-    uint8_t* buf_;
-    uint8_t* pos_;
-    uint8_t* end_;
-};
-
 ssize_t CompressedSnapshotReader::Read(void* buf, size_t count) {
     // Find the start and end chunks, inclusive.
     uint64_t start_chunk = offset_ / block_size_;
@@ -167,69 +133,48 @@
     // Chop off the first N bytes if the position is not block-aligned.
     size_t start_offset = offset_ % block_size_;
 
-    MemoryByteSink sink(buf, count);
+    uint8_t* buf_pos = reinterpret_cast<uint8_t*>(buf);
+    size_t buf_remaining = count;
 
-    size_t initial_bytes = std::min(block_size_ - start_offset, sink.remaining());
-    ssize_t rv = ReadBlock(start_chunk, &sink, start_offset, initial_bytes);
+    size_t initial_bytes = std::min(block_size_ - start_offset, buf_remaining);
+    ssize_t rv = ReadBlock(start_chunk, start_offset, buf_pos, initial_bytes);
     if (rv < 0) {
         return -1;
     }
     offset_ += rv;
+    buf_pos += rv;
+    buf_remaining -= rv;
 
     for (uint64_t chunk = start_chunk + 1; chunk < end_chunk; chunk++) {
-        ssize_t rv = ReadBlock(chunk, &sink, 0);
+        ssize_t rv = ReadBlock(chunk, 0, buf_pos, buf_remaining);
         if (rv < 0) {
             return -1;
         }
         offset_ += rv;
+        buf_pos += rv;
+        buf_remaining -= rv;
     }
 
-    if (sink.remaining()) {
-        ssize_t rv = ReadBlock(end_chunk, &sink, 0, {sink.remaining()});
+    if (buf_remaining) {
+        ssize_t rv = ReadBlock(end_chunk, 0, buf_pos, buf_remaining);
         if (rv < 0) {
             return -1;
         }
         offset_ += rv;
+        buf_pos += rv;
+        buf_remaining -= rv;
     }
 
+    CHECK_EQ(buf_pos - reinterpret_cast<uint8_t*>(buf), count);
+    CHECK_EQ(buf_remaining, 0);
+
     errno = 0;
-
-    DCHECK(sink.pos() - sink.buf() == count);
     return count;
 }
 
-// Discard the first N bytes of a sink request, or any excess bytes.
-class PartialSink : public MemoryByteSink {
-  public:
-    PartialSink(void* buffer, size_t size, size_t ignore_start)
-        : MemoryByteSink(buffer, size), ignore_start_(ignore_start) {}
-
-    void* GetBuffer(size_t requested, size_t* actual) override {
-        // Throw away the first N bytes if needed.
-        if (ignore_start_) {
-            *actual = std::min({requested, ignore_start_, sizeof(discard_)});
-            ignore_start_ -= *actual;
-            return discard_;
-        }
-        // Throw away any excess bytes if needed.
-        if (remaining() == 0) {
-            *actual = std::min(requested, sizeof(discard_));
-            return discard_;
-        }
-        return MemoryByteSink::GetBuffer(requested, actual);
-    }
-
-  private:
-    size_t ignore_start_;
-    char discard_[BLOCK_SZ];
-};
-
-ssize_t CompressedSnapshotReader::ReadBlock(uint64_t chunk, IByteSink* sink, size_t start_offset,
-                                            const std::optional<uint64_t>& max_bytes) {
-    size_t bytes_to_read = block_size_;
-    if (max_bytes) {
-        bytes_to_read = *max_bytes;
-    }
+ssize_t CompressedSnapshotReader::ReadBlock(uint64_t chunk, size_t start_offset, void* buffer,
+                                            size_t buffer_size) {
+    size_t bytes_to_read = std::min(static_cast<size_t>(block_size_), buffer_size);
 
     // The offset is relative to the chunk; we should be reading no more than
     // one chunk.
@@ -240,17 +185,6 @@
         op = ops_[chunk];
     }
 
-    size_t actual;
-    void* buffer = sink->GetBuffer(bytes_to_read, &actual);
-    if (!buffer || actual < bytes_to_read) {
-        // This should never happen unless we calculated the read size wrong
-        // somewhere. MemoryByteSink always fulfills the entire requested
-        // region unless there's not enough buffer remaining.
-        LOG(ERROR) << "Asked for buffer of size " << bytes_to_read << ", got " << actual;
-        errno = EINVAL;
-        return -1;
-    }
-
     if (!op || op->type == kCowCopyOp) {
         borrowed_fd fd = GetSourceFd();
         if (fd < 0) {
@@ -271,8 +205,7 @@
     } else if (op->type == kCowZeroOp) {
         memset(buffer, 0, bytes_to_read);
     } else if (op->type == kCowReplaceOp) {
-        PartialSink partial_sink(buffer, bytes_to_read, start_offset);
-        if (!cow_->ReadData(*op, &partial_sink)) {
+        if (cow_->ReadData(*op, buffer, bytes_to_read, start_offset) < bytes_to_read) {
             LOG(ERROR) << "CompressedSnapshotReader failed to read replace op";
             errno = EIO;
             return -1;
@@ -285,18 +218,20 @@
         }
 
         off64_t offset = op->source + start_offset;
-        char data[BLOCK_SZ];
-        if (!android::base::ReadFullyAtOffset(fd, &data, bytes_to_read, offset)) {
+
+        std::string data(bytes_to_read, '\0');
+        if (!android::base::ReadFullyAtOffset(fd, data.data(), data.size(), offset)) {
             PLOG(ERROR) << "read " << *source_device_;
             // ReadFullyAtOffset sets errno.
             return -1;
         }
-        PartialSink partial_sink(buffer, bytes_to_read, start_offset);
-        if (!cow_->ReadData(*op, &partial_sink)) {
+
+        if (cow_->ReadData(*op, buffer, bytes_to_read, start_offset) < bytes_to_read) {
             LOG(ERROR) << "CompressedSnapshotReader failed to read xor op";
             errno = EIO;
             return -1;
         }
+
         for (size_t i = 0; i < bytes_to_read; i++) {
             ((char*)buffer)[i] ^= data[i];
         }
diff --git a/fs_mgr/libsnapshot/snapshot_reader.h b/fs_mgr/libsnapshot/snapshot_reader.h
index a3e7e22..5e19c62 100644
--- a/fs_mgr/libsnapshot/snapshot_reader.h
+++ b/fs_mgr/libsnapshot/snapshot_reader.h
@@ -65,8 +65,7 @@
     bool Flush() override;
 
   private:
-    ssize_t ReadBlock(uint64_t chunk, IByteSink* sink, size_t start_offset,
-                      const std::optional<uint64_t>& max_bytes = {});
+    ssize_t ReadBlock(uint64_t chunk, size_t start_offset, void* buffer, size_t size);
     android::base::borrowed_fd GetSourceFd();
 
     std::unique_ptr<CowReader> cow_;
diff --git a/fs_mgr/libsnapshot/snapshot_reader_test.cpp b/fs_mgr/libsnapshot/snapshot_reader_test.cpp
index 9adc655..f25023d 100644
--- a/fs_mgr/libsnapshot/snapshot_reader_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_reader_test.cpp
@@ -140,6 +140,18 @@
         ASSERT_EQ(reader->Seek(offset, SEEK_SET), offset);
         ASSERT_EQ(reader->Read(&value, sizeof(value)), sizeof(value));
         ASSERT_EQ(value, MakeNewBlockString()[1000]);
+
+        // Test a sequence of one byte reads.
+        offset = 5 * kBlockSize + 10;
+        std::string expected = MakeNewBlockString().substr(10, 20);
+        ASSERT_EQ(reader->Seek(offset, SEEK_SET), offset);
+
+        std::string got;
+        while (got.size() < expected.size()) {
+            ASSERT_EQ(reader->Read(&value, sizeof(value)), sizeof(value));
+            got.push_back(value);
+        }
+        ASSERT_EQ(got, expected);
     }
 
     void TestReads(ISnapshotWriter* writer) {
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 460d49d..1fbfaf7 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -196,6 +196,17 @@
         return true;
     }
 
+    bool ShouldSkipLegacyMerging() {
+        if (!GetLegacyCompressionEnabledProperty() || !snapuserd_required_) {
+            return false;
+        }
+        int api_level = android::base::GetIntProperty("ro.board.api_level", -1);
+        if (api_level == -1) {
+            api_level = android::base::GetIntProperty("ro.product.first_api_level", -1);
+        }
+        return api_level != __ANDROID_API_S__;
+    }
+
     void InitializeState() {
         ASSERT_TRUE(sm->EnsureImageManager());
         image_manager_ = sm->image_manager();
@@ -654,6 +665,10 @@
 
     test_device->set_slot_suffix("_b");
     ASSERT_TRUE(sm->CreateLogicalAndSnapshotPartitions("super", snapshot_timeout_));
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(sm->InitiateMerge());
 
     // The device should have been switched to a snapshot-merge target.
@@ -761,6 +776,10 @@
     ASSERT_NE(init, nullptr);
     ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super", snapshot_timeout_));
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
 
     // Now, reflash super. Note that we haven't called ProcessUpdateState, so the
@@ -1344,6 +1363,10 @@
     }
 
     // Initiate the merge and wait for it to be completed.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(init->IsSnapuserdRequired(), snapuserd_required_);
     {
@@ -1407,6 +1430,10 @@
     ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super", snapshot_timeout_));
 
     // Initiate the merge and wait for it to be completed.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(UpdateState::MergeCompleted, init->ProcessUpdateState());
 }
@@ -1476,6 +1503,10 @@
     }
 
     // Initiate the merge and wait for it to be completed.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(init->IsSnapuserdRequired(), snapuserd_required_);
     {
@@ -1584,6 +1615,10 @@
             });
 
     // Initiate the merge and wait for it to be completed.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(init->IsSnapuserdRequired(), snapuserd_required_);
     {
@@ -1786,6 +1821,10 @@
 
     // Initiate the merge and wait for it to be completed.
     auto new_sm = SnapshotManager::New(new TestDeviceInfo(fake_super, "_b"));
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(new_sm->InitiateMerge());
     ASSERT_EQ(UpdateState::MergeCompleted, new_sm->ProcessUpdateState());
 
@@ -1924,6 +1963,10 @@
     ASSERT_GE(fd, 0);
 
     // COW cannot be removed due to open fd, so expect a soft failure.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(UpdateState::MergeNeedsReboot, init->ProcessUpdateState());
 
@@ -2027,6 +2070,10 @@
 
     // Initiate the merge and then immediately stop it to simulate a reboot.
     auto new_sm = SnapshotManager::New(new TestDeviceInfo(fake_super, "_b"));
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(new_sm->InitiateMerge());
     ASSERT_TRUE(UnmapAll());
 
@@ -2059,6 +2106,10 @@
 
     // Initiate the merge and then immediately stop it to simulate a reboot.
     auto new_sm = SnapshotManager::New(new TestDeviceInfo(fake_super, "_b"));
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(new_sm->InitiateMerge());
     ASSERT_TRUE(UnmapAll());
 
@@ -2136,6 +2187,10 @@
 
 // Test update package that requests data wipe.
 TEST_F(SnapshotUpdateTest, DataWipeRequiredInPackage) {
+    if (ShouldSkipLegacyMerging()) {
+        GTEST_SKIP() << "Skipping legacy merge in test";
+    }
+
     AddOperationForPartitions();
     // Execute the update.
     ASSERT_TRUE(sm->BeginUpdate());
@@ -2175,6 +2230,10 @@
 
 // Test update package that requests data wipe.
 TEST_F(SnapshotUpdateTest, DataWipeWithStaleSnapshots) {
+    if (ShouldSkipLegacyMerging()) {
+        GTEST_SKIP() << "Skipping legacy merge in test";
+    }
+
     AddOperationForPartitions();
 
     // Execute the update.
@@ -2397,6 +2456,10 @@
     }
 
     // Initiate the merge and wait for it to be completed.
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(UpdateState::MergeCompleted, init->ProcessUpdateState());
 
@@ -2583,6 +2646,11 @@
     ASSERT_TRUE(init->InitiateMerge());
     ASSERT_EQ(UpdateState::MergeFailed, init->ProcessUpdateState());
 
+    if (ShouldSkipLegacyMerging()) {
+        LOG(INFO) << "Skipping legacy merge in test";
+        return;
+    }
+
     // Simulate a reboot that tries the merge again, with the non-failing dm.
     ASSERT_TRUE(UnmapAll());
     init = NewManagerForFirstStageMount("_b");
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
index 0a98b18..376e070 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
@@ -347,7 +347,6 @@
  */
 bool Snapuserd::ReadMetadata() {
     reader_ = std::make_unique<CowReader>();
-    CowHeader header;
     CowOptions options;
     bool metadata_found = false;
     int replace_ops = 0, zero_ops = 0, copy_ops = 0;
@@ -359,11 +358,7 @@
         return false;
     }
 
-    if (!reader_->GetHeader(&header)) {
-        SNAP_LOG(ERROR) << "Failed to get header";
-        return false;
-    }
-
+    const auto& header = reader_->GetHeader();
     if (!(header.block_size == BLOCK_SZ)) {
         SNAP_LOG(ERROR) << "Invalid header block size found: " << header.block_size;
         return false;
@@ -395,7 +390,7 @@
     // this memset will ensure that metadata read is completed.
     memset(de_ptr.get(), 0, (exceptions_per_area_ * sizeof(struct disk_exception)));
 
-    while (!cowop_rm_iter->Done()) {
+    while (!cowop_rm_iter->AtEnd()) {
         const CowOperation* cow_op = &cowop_rm_iter->Get();
         struct disk_exception* de =
                 reinterpret_cast<struct disk_exception*>((char*)de_ptr.get() + offset);
@@ -442,7 +437,7 @@
                                                  sizeof(struct disk_exception));
             memset(de_ptr.get(), 0, (exceptions_per_area_ * sizeof(struct disk_exception)));
 
-            if (cowop_rm_iter->Done()) {
+            if (cowop_rm_iter->AtEnd()) {
                 vec_.push_back(std::move(de_ptr));
             }
         }
@@ -462,7 +457,7 @@
                     << " Number of replace/zero ops completed in this area: " << num_ops
                     << " Pending copy ops for this area: " << pending_ordered_ops;
 
-    while (!cowop_rm_iter->Done()) {
+    while (!cowop_rm_iter->AtEnd()) {
         do {
             const CowOperation* cow_op = &cowop_rm_iter->Get();
 
@@ -526,7 +521,7 @@
             source_blocks.insert(cow_op->new_block);
             prev_id = cow_op->new_block;
             cowop_rm_iter->Next();
-        } while (!cowop_rm_iter->Done() && pending_ordered_ops);
+        } while (!cowop_rm_iter->AtEnd() && pending_ordered_ops);
 
         data_chunk_id = GetNextAllocatableChunkId(data_chunk_id);
         SNAP_LOG(DEBUG) << "Batch Merge copy-ops of size: " << vec.size()
@@ -569,7 +564,7 @@
                                                      sizeof(struct disk_exception));
                 memset(de_ptr.get(), 0, (exceptions_per_area_ * sizeof(struct disk_exception)));
 
-                if (cowop_rm_iter->Done()) {
+                if (cowop_rm_iter->AtEnd()) {
                     vec_.push_back(std::move(de_ptr));
                     SNAP_LOG(DEBUG) << "ReadMetadata() completed; Number of Areas: " << vec_.size();
                 }
@@ -631,8 +626,7 @@
 }
 
 bool Snapuserd::MmapMetadata() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     if (header.major_version >= 2 && header.buffer_size > 0) {
         total_mapped_addr_length_ = header.header_size + BUFFER_REGION_DEFAULT_SIZE;
@@ -827,8 +821,7 @@
 }
 
 uint64_t Snapuserd::GetBufferMetadataOffset() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     size_t size = header.header_size + sizeof(BufferState);
     return size;
@@ -843,16 +836,14 @@
  *
  */
 size_t Snapuserd::GetBufferMetadataSize() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     size_t metadata_bytes = (header.buffer_size * sizeof(struct ScratchMetadata)) / BLOCK_SZ;
     return metadata_bytes;
 }
 
 size_t Snapuserd::GetBufferDataOffset() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     return (header.header_size + GetBufferMetadataSize());
 }
@@ -861,16 +852,14 @@
  * (2MB - 8K = 2088960 bytes) will be the buffer region to hold the data.
  */
 size_t Snapuserd::GetBufferDataSize() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     size_t size = header.buffer_size - GetBufferMetadataSize();
     return size;
 }
 
 struct BufferState* Snapuserd::GetBufferState() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     struct BufferState* ra_state =
             reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.header_size);
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
index 965af40..31a80a3 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
@@ -95,11 +95,17 @@
 // internal COW format and if the block is compressed,
 // it will be de-compressed.
 bool WorkerThread::ProcessReplaceOp(const CowOperation* cow_op) {
-    if (!reader_->ReadData(*cow_op, &bufsink_)) {
-        SNAP_LOG(ERROR) << "ProcessReplaceOp failed for block " << cow_op->new_block;
+    void* buffer = bufsink_.GetPayloadBuffer(BLOCK_SZ);
+    if (!buffer) {
+        SNAP_LOG(ERROR) << "No space in buffer sink";
         return false;
     }
-
+    ssize_t rv = reader_->ReadData(*cow_op, buffer, BLOCK_SZ);
+    if (rv != BLOCK_SZ) {
+        SNAP_LOG(ERROR) << "ProcessReplaceOp failed for block " << cow_op->new_block
+                        << ", return = " << rv;
+        return false;
+    }
     return true;
 }
 
diff --git a/fs_mgr/libsnapshot/snapuserd/include/snapuserd/snapuserd_buffer.h b/fs_mgr/libsnapshot/snapuserd/include/snapuserd/snapuserd_buffer.h
index 2e4cac6..a6b6a7f 100644
--- a/fs_mgr/libsnapshot/snapuserd/include/snapuserd/snapuserd_buffer.h
+++ b/fs_mgr/libsnapshot/snapuserd/include/snapuserd/snapuserd_buffer.h
@@ -25,16 +25,15 @@
 namespace android {
 namespace snapshot {
 
-class BufferSink : public IByteSink {
+class BufferSink final {
   public:
     void Initialize(size_t size);
     void* GetBufPtr() { return buffer_.get(); }
     void Clear() { memset(GetBufPtr(), 0, buffer_size_); }
     void* GetPayloadBuffer(size_t size);
-    void* GetBuffer(size_t requested, size_t* actual) override;
+    void* GetBuffer(size_t requested, size_t* actual);
     void UpdateBufferOffset(size_t size) { buffer_offset_ += size; }
     struct dm_user_header* GetHeaderPtr();
-    bool ReturnData(void*, size_t) override { return true; }
     void ResetBufferOffset() { buffer_offset_ = 0; }
     void* GetPayloadBufPtr();
 
@@ -44,12 +43,12 @@
     size_t buffer_size_;
 };
 
-class XorSink : public IByteSink {
+class XorSink final {
   public:
     void Initialize(BufferSink* sink, size_t size);
     void Reset();
-    void* GetBuffer(size_t requested, size_t* actual) override;
-    bool ReturnData(void* buffer, size_t len) override;
+    void* GetBuffer(size_t requested, size_t* actual);
+    bool ReturnData(void* buffer, size_t len);
 
   private:
     BufferSink* bufsink_;
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
index 25ce0ae..9df8cf9 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
@@ -98,8 +98,7 @@
         }
     } else {
         reader_->UpdateMergeOpsCompleted(num_merge_ops);
-        CowHeader header;
-        reader_->GetHeader(&header);
+        const auto& header = reader_->GetHeader();
 
         if (lseek(cow_fd_.get(), 0, SEEK_SET) < 0) {
             SNAP_PLOG(ERROR) << "lseek failed";
@@ -154,7 +153,6 @@
 
 bool SnapshotHandler::ReadMetadata() {
     reader_ = std::make_unique<CowReader>(CowReader::ReaderFlags::USERSPACE_MERGE, true);
-    CowHeader header;
     CowOptions options;
 
     SNAP_LOG(DEBUG) << "ReadMetadata: Parsing cow file";
@@ -164,11 +162,7 @@
         return false;
     }
 
-    if (!reader_->GetHeader(&header)) {
-        SNAP_LOG(ERROR) << "Failed to get header";
-        return false;
-    }
-
+    const auto& header = reader_->GetHeader();
     if (!(header.block_size == BLOCK_SZ)) {
         SNAP_LOG(ERROR) << "Invalid header block size found: " << header.block_size;
         return false;
@@ -191,7 +185,7 @@
 
     size_t copy_ops = 0, replace_ops = 0, zero_ops = 0, xor_ops = 0;
 
-    while (!cowop_iter->Done()) {
+    while (!cowop_iter->AtEnd()) {
         const CowOperation* cow_op = &cowop_iter->Get();
 
         if (cow_op->type == kCowCopyOp) {
@@ -244,8 +238,7 @@
 }
 
 bool SnapshotHandler::MmapMetadata() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     total_mapped_addr_length_ = header.header_size + BUFFER_REGION_DEFAULT_SIZE;
 
@@ -367,8 +360,7 @@
 }
 
 uint64_t SnapshotHandler::GetBufferMetadataOffset() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     return (header.header_size + sizeof(BufferState));
 }
@@ -383,8 +375,7 @@
  *
  */
 size_t SnapshotHandler::GetBufferMetadataSize() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
     size_t buffer_size = header.buffer_size;
 
     // If there is no scratch space, then just use the
@@ -397,8 +388,7 @@
 }
 
 size_t SnapshotHandler::GetBufferDataOffset() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     return (header.header_size + GetBufferMetadataSize());
 }
@@ -407,8 +397,7 @@
  * (2MB - 8K = 2088960 bytes) will be the buffer region to hold the data.
  */
 size_t SnapshotHandler::GetBufferDataSize() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
     size_t buffer_size = header.buffer_size;
 
     // If there is no scratch space, then just use the
@@ -421,8 +410,7 @@
 }
 
 struct BufferState* SnapshotHandler::GetBufferState() {
-    CowHeader header;
-    reader_->GetHeader(&header);
+    const auto& header = reader_->GetHeader();
 
     struct BufferState* ra_state =
             reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.header_size);
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
index 0d0f711..3bc02d4 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
@@ -76,11 +76,15 @@
 // internal COW format and if the block is compressed,
 // it will be de-compressed.
 bool Worker::ProcessReplaceOp(const CowOperation* cow_op) {
-    if (!reader_->ReadData(*cow_op, &bufsink_)) {
+    void* buffer = bufsink_.GetPayloadBuffer(BLOCK_SZ);
+    if (!buffer) {
+        SNAP_LOG(ERROR) << "ProcessReplaceOp failed to allocate buffer";
+        return false;
+    }
+    if (!reader_->ReadData(*cow_op, buffer, BLOCK_SZ)) {
         SNAP_LOG(ERROR) << "ProcessReplaceOp failed for block " << cow_op->new_block;
         return false;
     }
-
     return true;
 }
 
@@ -125,12 +129,26 @@
     if (!ReadFromSourceDevice(cow_op)) {
         return false;
     }
+
     xorsink_.Reset();
-    if (!reader_->ReadData(*cow_op, &xorsink_)) {
-        SNAP_LOG(ERROR) << "ProcessXorOp failed for block " << cow_op->new_block;
+
+    size_t actual = 0;
+    void* buffer = xorsink_.GetBuffer(BLOCK_SZ, &actual);
+    if (!buffer || actual < BLOCK_SZ) {
+        SNAP_LOG(ERROR) << "ProcessXorOp failed to get buffer of " << BLOCK_SZ << " size, got "
+                        << actual;
         return false;
     }
-
+    ssize_t size = reader_->ReadData(*cow_op, buffer, BLOCK_SZ);
+    if (size != BLOCK_SZ) {
+        SNAP_LOG(ERROR) << "ProcessXorOp failed for block " << cow_op->new_block
+                        << ", return value: " << size;
+        return false;
+    }
+    if (!xorsink_.ReturnData(buffer, size)) {
+        SNAP_LOG(ERROR) << "ProcessXorOp failed to return data";
+        return false;
+    }
     return true;
 }
 
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_merge.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_merge.cpp
index d57f434..4d91ff3 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_merge.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_merge.cpp
@@ -30,7 +30,7 @@
     bool checkOrderedOp = (replace_zero_vec == nullptr);
 
     do {
-        if (!cowop_iter_->Done() && num_ops) {
+        if (!cowop_iter_->AtEnd() && num_ops) {
             const CowOperation* cow_op = &cowop_iter_->Get();
             if (checkOrderedOp && !IsOrderedOp(*cow_op)) {
                 break;
@@ -45,7 +45,7 @@
             num_ops -= 1;
             nr_consecutive = 1;
 
-            while (!cowop_iter_->Done() && num_ops) {
+            while (!cowop_iter_->AtEnd() && num_ops) {
                 const CowOperation* op = &cowop_iter_->Get();
                 if (checkOrderedOp && !IsOrderedOp(*op)) {
                     break;
@@ -85,7 +85,7 @@
 
     SNAP_LOG(INFO) << "MergeReplaceZeroOps started....";
 
-    while (!cowop_iter_->Done()) {
+    while (!cowop_iter_->AtEnd()) {
         int num_ops = PAYLOAD_BUFFER_SZ / BLOCK_SZ;
         std::vector<const CowOperation*> replace_zero_vec;
         uint64_t source_offset;
@@ -93,7 +93,7 @@
         int linear_blocks = PrepareMerge(&source_offset, &num_ops, &replace_zero_vec);
         if (linear_blocks == 0) {
             // Merge complete
-            CHECK(cowop_iter_->Done());
+            CHECK(cowop_iter_->AtEnd());
             break;
         }
 
@@ -180,7 +180,7 @@
 
     SNAP_LOG(INFO) << "MergeOrderedOpsAsync started....";
 
-    while (!cowop_iter_->Done()) {
+    while (!cowop_iter_->AtEnd()) {
         const CowOperation* cow_op = &cowop_iter_->Get();
         if (!IsOrderedOp(*cow_op)) {
             break;
@@ -361,7 +361,7 @@
 
     SNAP_LOG(INFO) << "MergeOrderedOps started....";
 
-    while (!cowop_iter_->Done()) {
+    while (!cowop_iter_->AtEnd()) {
         const CowOperation* cow_op = &cowop_iter_->Get();
         if (!IsOrderedOp(*cow_op)) {
             break;
@@ -443,7 +443,7 @@
     if (!MergeOrderedOpsAsync()) {
         SNAP_LOG(ERROR) << "MergeOrderedOpsAsync failed - Falling back to synchronous I/O";
         // Reset the iter so that we retry the merge
-        while (blocks_merged_in_group_ && !cowop_iter_->RDone()) {
+        while (blocks_merged_in_group_ && !cowop_iter_->AtBegin()) {
             cowop_iter_->Prev();
             blocks_merged_in_group_ -= 1;
         }
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
index fbe57d2..4aad7a6 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
@@ -114,6 +114,24 @@
     return nr_consecutive;
 }
 
+class [[nodiscard]] AutoNotifyReadAheadFailed {
+  public:
+    AutoNotifyReadAheadFailed(std::shared_ptr<SnapshotHandler> snapuserd) : snapuserd_(snapuserd) {}
+
+    ~AutoNotifyReadAheadFailed() {
+        if (cancelled_) {
+            return;
+        }
+        snapuserd_->ReadAheadIOFailed();
+    }
+
+    void Cancel() { cancelled_ = true; }
+
+  private:
+    std::shared_ptr<SnapshotHandler> snapuserd_;
+    bool cancelled_ = false;
+};
+
 bool ReadAhead::ReconstructDataFromCow() {
     std::unordered_map<uint64_t, void*>& read_ahead_buffer_map = snapuserd_->GetReadAheadMap();
     loff_t metadata_offset = 0;
@@ -145,6 +163,8 @@
         metadata_offset += sizeof(struct ScratchMetadata);
     }
 
+    AutoNotifyReadAheadFailed notify_read_ahead_failed(snapuserd_);
+
     // We are done re-constructing the mapping; however, we need to make sure
     // all the COW operations to-be merged are present in the re-constructed
     // mapping.
@@ -162,7 +182,6 @@
         if (!(num_ops == 0)) {
             SNAP_LOG(ERROR) << "ReconstructDataFromCow failed. Not all ops recoverd "
                             << " Pending ops: " << num_ops;
-            snapuserd_->ReadAheadIOFailed();
             return false;
         }
 
@@ -175,11 +194,11 @@
 
     if (!snapuserd_->ReadAheadIOCompleted(true)) {
         SNAP_LOG(ERROR) << "ReadAheadIOCompleted failed...";
-        snapuserd_->ReadAheadIOFailed();
         return false;
     }
 
     SNAP_LOG(INFO) << "ReconstructDataFromCow success";
+    notify_read_ahead_failed.Cancel();
     return true;
 }
 
@@ -467,9 +486,16 @@
         if (xor_op_index < xor_op_vec.size()) {
             const CowOperation* xor_op = xor_op_vec[xor_op_index];
             if (xor_op->new_block == new_block) {
-                if (!reader_->ReadData(*xor_op, &bufsink_)) {
+                void* buffer = bufsink_.GetPayloadBuffer(BLOCK_SZ);
+                if (!buffer) {
+                    SNAP_LOG(ERROR) << "ReadAhead - failed to allocate buffer for block: "
+                                    << xor_op->new_block;
+                    return false;
+                }
+                if (ssize_t rv = reader_->ReadData(*xor_op, buffer, BLOCK_SZ); rv != BLOCK_SZ) {
                     SNAP_LOG(ERROR)
-                            << " ReadAhead - XorOp Read failed for block: " << xor_op->new_block;
+                            << " ReadAhead - XorOp Read failed for block: " << xor_op->new_block
+                            << ", return value: " << rv;
                     return false;
                 }
 
@@ -492,6 +518,8 @@
     blocks_.clear();
     std::vector<const CowOperation*> xor_op_vec;
 
+    AutoNotifyReadAheadFailed notify_read_ahead_failed(snapuserd_);
+
     bufsink_.ResetBufferOffset();
 
     // Number of ops to be merged in this window. This is a fixed size
@@ -518,8 +546,6 @@
                              << " offset :" << source_offset % BLOCK_SZ
                              << " buffer_offset : " << buffer_offset << " io_size : " << io_size
                              << " buf-addr : " << read_ahead_buffer_;
-
-            snapuserd_->ReadAheadIOFailed();
             return false;
         }
 
@@ -530,6 +556,7 @@
 
     // Done with merging ordered ops
     if (RAIterDone() && total_blocks_merged_ == 0) {
+        notify_read_ahead_failed.Cancel();
         return true;
     }
 
@@ -560,20 +587,25 @@
             // Check if this block is an XOR op
             if (xor_op->new_block == new_block) {
                 // Read the xor'ed data from COW
-                if (!reader_->ReadData(*xor_op, &bufsink)) {
+                void* buffer = bufsink_.GetPayloadBuffer(BLOCK_SZ);
+                if (!buffer) {
+                    SNAP_LOG(ERROR) << "ReadAhead - failed to allocate buffer";
+                    return false;
+                }
+                if (ssize_t rv = reader_->ReadData(*xor_op, buffer, BLOCK_SZ); rv != BLOCK_SZ) {
                     SNAP_LOG(ERROR)
-                            << " ReadAhead - XorOp Read failed for block: " << xor_op->new_block;
-                    snapuserd_->ReadAheadIOFailed();
+                            << " ReadAhead - XorOp Read failed for block: " << xor_op->new_block
+                            << ", return value: " << rv;
                     return false;
                 }
                 // Pointer to the data read from base device
-                uint8_t* buffer = reinterpret_cast<uint8_t*>(bufptr);
+                uint8_t* read_buffer = reinterpret_cast<uint8_t*>(bufptr);
                 // Get the xor'ed data read from COW device
                 uint8_t* xor_data = reinterpret_cast<uint8_t*>(bufsink.GetPayloadBufPtr());
 
                 // Retrieve the original data
                 for (size_t byte_offset = 0; byte_offset < BLOCK_SZ; byte_offset++) {
-                    buffer[byte_offset] ^= xor_data[byte_offset];
+                    read_buffer[byte_offset] ^= xor_data[byte_offset];
                 }
 
                 // Move to next XOR op
@@ -604,6 +636,7 @@
     bm->new_block = 0;
     bm->file_offset = 0;
 
+    notify_read_ahead_failed.Cancel();
     return true;
 }
 
@@ -776,7 +809,7 @@
 }
 
 bool ReadAhead::RAIterDone() {
-    if (cowop_iter_->Done()) {
+    if (cowop_iter_->AtEnd()) {
         return true;
     }
 
@@ -794,7 +827,7 @@
 }
 
 void ReadAhead::RAResetIter(uint64_t num_blocks) {
-    while (num_blocks && !cowop_iter_->RDone()) {
+    while (num_blocks && !cowop_iter_->AtBegin()) {
         cowop_iter_->Prev();
         num_blocks -= 1;
     }
diff --git a/gatekeeperd/Android.bp b/gatekeeperd/Android.bp
index 838f734..534fc1a 100644
--- a/gatekeeperd/Android.bp
+++ b/gatekeeperd/Android.bp
@@ -18,8 +18,8 @@
     default_applicable_licenses: ["Android-Apache-2.0"],
 }
 
-cc_binary {
-    name: "gatekeeperd",
+cc_defaults {
+    name: "gatekeeperd_defaults",
     cflags: [
         "-Wall",
         "-Wextra",
@@ -52,6 +52,16 @@
 
     static_libs: ["libscrypt_static"],
     include_dirs: ["external/scrypt/lib/crypto"],
+}
+
+cc_binary {
+    name: "gatekeeperd",
+    defaults: [
+        "gatekeeperd_defaults",
+    ],
+    srcs: [
+        "main.cpp",
+    ],
     init_rc: ["gatekeeperd.rc"],
 }
 
@@ -88,3 +98,20 @@
         "libbinder",
     ],
 }
+
+cc_fuzz {
+    name: "gatekeeperd_service_fuzzer",
+    defaults: [
+        "gatekeeperd_defaults",
+        "service_fuzzer_defaults"
+    ],
+    srcs: [
+        "fuzzer/GateKeeperServiceFuzzer.cpp",
+    ],
+    fuzz_config: {
+        cc: [
+            "subrahmanyaman@google.com",
+            "swillden@google.com",
+        ],
+    },
+}
\ No newline at end of file
diff --git a/gatekeeperd/fuzzer/GateKeeperServiceFuzzer.cpp b/gatekeeperd/fuzzer/GateKeeperServiceFuzzer.cpp
new file mode 100644
index 0000000..bc0d5fe
--- /dev/null
+++ b/gatekeeperd/fuzzer/GateKeeperServiceFuzzer.cpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2023 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 <fuzzbinder/libbinder_driver.h>
+
+#include "gatekeeperd.h"
+
+using android::fuzzService;
+using android::GateKeeperProxy;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    auto gatekeeperService = new GateKeeperProxy();
+    fuzzService(gatekeeperService, FuzzedDataProvider(data, size));
+    return 0;
+}
\ No newline at end of file
diff --git a/gatekeeperd/gatekeeperd.cpp b/gatekeeperd/gatekeeperd.cpp
index eb43a33..e5241b5 100644
--- a/gatekeeperd/gatekeeperd.cpp
+++ b/gatekeeperd/gatekeeperd.cpp
@@ -13,11 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 #define LOG_TAG "gatekeeperd"
 
-#include <android/service/gatekeeper/BnGateKeeperService.h>
-#include <gatekeeper/GateKeeperResponse.h>
+#include "gatekeeperd.h"
 
 #include <endian.h>
 #include <errno.h>
@@ -39,25 +37,18 @@
 #include <log/log.h>
 #include <utils/String16.h>
 
-#include <aidl/android/hardware/gatekeeper/IGatekeeper.h>
 #include <aidl/android/hardware/security/keymint/HardwareAuthToken.h>
 #include <aidl/android/security/authorization/IKeystoreAuthorization.h>
-#include <android/hardware/gatekeeper/1.0/IGatekeeper.h>
 #include <hidl/HidlSupport.h>
 
 using android::sp;
 using android::hardware::Return;
 using android::hardware::gatekeeper::V1_0::GatekeeperResponse;
 using android::hardware::gatekeeper::V1_0::GatekeeperStatusCode;
-using android::hardware::gatekeeper::V1_0::IGatekeeper;
 
 using AidlGatekeeperEnrollResp = aidl::android::hardware::gatekeeper::GatekeeperEnrollResponse;
 using AidlGatekeeperVerifyResp = aidl::android::hardware::gatekeeper::GatekeeperVerifyResponse;
-using AidlIGatekeeper = aidl::android::hardware::gatekeeper::IGatekeeper;
 
-using ::android::binder::Status;
-using ::android::service::gatekeeper::BnGateKeeperService;
-using GKResponse = ::android::service::gatekeeper::GateKeeperResponse;
 using GKResponseCode = ::android::service::gatekeeper::ResponseCode;
 using ::aidl::android::hardware::security::keymint::HardwareAuthenticatorType;
 using ::aidl::android::hardware::security::keymint::HardwareAuthToken;
@@ -70,172 +61,167 @@
 static const String16 DUMP_PERMISSION("android.permission.DUMP");
 constexpr const char gatekeeperServiceName[] = "android.hardware.gatekeeper.IGatekeeper/default";
 
-class GateKeeperProxy : public BnGateKeeperService {
-  public:
-    GateKeeperProxy() {
-        clear_state_if_needed_done = false;
-        hw_device = IGatekeeper::getService();
-        ::ndk::SpAIBinder ks2Binder(AServiceManager_getService(gatekeeperServiceName));
-        aidl_hw_device = AidlIGatekeeper::fromBinder(ks2Binder);
-        is_running_gsi = android::base::GetBoolProperty(android::gsi::kGsiBootedProp, false);
+GateKeeperProxy::GateKeeperProxy() {
+    clear_state_if_needed_done = false;
+    hw_device = IGatekeeper::getService();
+    ::ndk::SpAIBinder ks2Binder(AServiceManager_getService(gatekeeperServiceName));
+    aidl_hw_device = AidlIGatekeeper::fromBinder(ks2Binder);
+    is_running_gsi = android::base::GetBoolProperty(android::gsi::kGsiBootedProp, false);
 
-        if (!aidl_hw_device && !hw_device) {
-            LOG(ERROR) << "Could not find Gatekeeper device, which makes me very sad.";
+    if (!aidl_hw_device && !hw_device) {
+        LOG(ERROR) << "Could not find Gatekeeper device, which makes me very sad.";
+    }
+}
+
+void GateKeeperProxy::store_sid(uint32_t userId, uint64_t sid) {
+    char filename[21];
+    snprintf(filename, sizeof(filename), "%u", userId);
+    int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
+    if (fd < 0) {
+        ALOGE("could not open file: %s: %s", filename, strerror(errno));
+        return;
+    }
+    write(fd, &sid, sizeof(sid));
+    close(fd);
+}
+
+void GateKeeperProxy::clear_state_if_needed() {
+    if (clear_state_if_needed_done) {
+        return;
+    }
+
+    if (mark_cold_boot() && !is_running_gsi) {
+        ALOGI("cold boot: clearing state");
+        if (aidl_hw_device) {
+            aidl_hw_device->deleteAllUsers();
+        } else if (hw_device) {
+            hw_device->deleteAllUsers([](const GatekeeperResponse&) {});
         }
     }
 
-    virtual ~GateKeeperProxy() {}
+    clear_state_if_needed_done = true;
+}
 
-    void store_sid(uint32_t userId, uint64_t sid) {
-        char filename[21];
-        snprintf(filename, sizeof(filename), "%u", userId);
+bool GateKeeperProxy::mark_cold_boot() {
+    const char* filename = ".coldboot";
+    if (access(filename, F_OK) == -1) {
         int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
         if (fd < 0) {
-            ALOGE("could not open file: %s: %s", filename, strerror(errno));
-            return;
+            ALOGE("could not open file: %s : %s", filename, strerror(errno));
+            return false;
         }
-        write(fd, &sid, sizeof(sid));
         close(fd);
+        return true;
     }
+    return false;
+}
 
-    void clear_state_if_needed() {
-        if (clear_state_if_needed_done) {
-            return;
-        }
-
-        if (mark_cold_boot() && !is_running_gsi) {
-            ALOGI("cold boot: clearing state");
-            if (aidl_hw_device) {
-                aidl_hw_device->deleteAllUsers();
-            } else if (hw_device) {
-                hw_device->deleteAllUsers([](const GatekeeperResponse&) {});
-            }
-        }
-
-        clear_state_if_needed_done = true;
+void GateKeeperProxy::maybe_store_sid(uint32_t userId, uint64_t sid) {
+    char filename[21];
+    snprintf(filename, sizeof(filename), "%u", userId);
+    if (access(filename, F_OK) == -1) {
+        store_sid(userId, sid);
     }
+}
 
-    bool mark_cold_boot() {
-        const char* filename = ".coldboot";
-        if (access(filename, F_OK) == -1) {
-            int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
-            if (fd < 0) {
-                ALOGE("could not open file: %s : %s", filename, strerror(errno));
-                return false;
-            }
-            close(fd);
-            return true;
-        }
-        return false;
-    }
+uint64_t GateKeeperProxy::read_sid(uint32_t userId) {
+    char filename[21];
+    uint64_t sid;
+    snprintf(filename, sizeof(filename), "%u", userId);
+    int fd = open(filename, O_RDONLY);
+    if (fd < 0) return 0;
+    read(fd, &sid, sizeof(sid));
+    close(fd);
+    return sid;
+}
 
-    void maybe_store_sid(uint32_t userId, uint64_t sid) {
-        char filename[21];
-        snprintf(filename, sizeof(filename), "%u", userId);
-        if (access(filename, F_OK) == -1) {
-            store_sid(userId, sid);
-        }
+void GateKeeperProxy::clear_sid(uint32_t userId) {
+    char filename[21];
+    snprintf(filename, sizeof(filename), "%u", userId);
+    if (remove(filename) < 0 && errno != ENOENT) {
+        ALOGE("%s: could not remove file [%s], attempting 0 write", __func__, strerror(errno));
+        store_sid(userId, 0);
     }
+}
 
-    uint64_t read_sid(uint32_t userId) {
-        char filename[21];
-        uint64_t sid;
-        snprintf(filename, sizeof(filename), "%u", userId);
-        int fd = open(filename, O_RDONLY);
-        if (fd < 0) return 0;
-        read(fd, &sid, sizeof(sid));
-        close(fd);
-        return sid;
+uint32_t GateKeeperProxy::adjust_userId(uint32_t userId) {
+    static constexpr uint32_t kGsiOffset = 1000000;
+    CHECK(userId < kGsiOffset);
+    CHECK((aidl_hw_device != nullptr) || (hw_device != nullptr));
+    if (is_running_gsi) {
+        return userId + kGsiOffset;
     }
-
-    void clear_sid(uint32_t userId) {
-        char filename[21];
-        snprintf(filename, sizeof(filename), "%u", userId);
-        if (remove(filename) < 0 && errno != ENOENT) {
-            ALOGE("%s: could not remove file [%s], attempting 0 write", __func__, strerror(errno));
-            store_sid(userId, 0);
-        }
-    }
-
-    // This should only be called on userIds being passed to the GateKeeper HAL. It ensures that
-    // secure storage shared across a GSI image and a host image will not overlap.
-    uint32_t adjust_userId(uint32_t userId) {
-        static constexpr uint32_t kGsiOffset = 1000000;
-        CHECK(userId < kGsiOffset);
-        CHECK((aidl_hw_device != nullptr) || (hw_device != nullptr));
-        if (is_running_gsi) {
-            return userId + kGsiOffset;
-        }
-        return userId;
-    }
+    return userId;
+}
 
 #define GK_ERROR *gkResponse = GKResponse::error(), Status::ok()
 
-    Status enroll(int32_t userId, const std::optional<std::vector<uint8_t>>& currentPasswordHandle,
-                  const std::optional<std::vector<uint8_t>>& currentPassword,
-                  const std::vector<uint8_t>& desiredPassword, GKResponse* gkResponse) override {
-        IPCThreadState* ipc = IPCThreadState::self();
-        const int calling_pid = ipc->getCallingPid();
-        const int calling_uid = ipc->getCallingUid();
-        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
-            return GK_ERROR;
-        }
+Status GateKeeperProxy::enroll(int32_t userId,
+                               const std::optional<std::vector<uint8_t>>& currentPasswordHandle,
+                               const std::optional<std::vector<uint8_t>>& currentPassword,
+                               const std::vector<uint8_t>& desiredPassword,
+                               GKResponse* gkResponse) {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int calling_pid = ipc->getCallingPid();
+    const int calling_uid = ipc->getCallingUid();
+    if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
+        return GK_ERROR;
+    }
 
-        // Make sure to clear any state from before factory reset as soon as a credential is
-        // enrolled (which may happen during device setup).
-        clear_state_if_needed();
+    // Make sure to clear any state from before factory reset as soon as a credential is
+    // enrolled (which may happen during device setup).
+    clear_state_if_needed();
 
-        // need a desired password to enroll
-        if (desiredPassword.size() == 0) return GK_ERROR;
+    // need a desired password to enroll
+    if (desiredPassword.size() == 0) return GK_ERROR;
 
-        if (!aidl_hw_device && !hw_device) {
-            LOG(ERROR) << "has no HAL to talk to";
-            return GK_ERROR;
-        }
+    if (!aidl_hw_device && !hw_device) {
+        LOG(ERROR) << "has no HAL to talk to";
+        return GK_ERROR;
+    }
 
-        android::hardware::hidl_vec<uint8_t> curPwdHandle;
-        android::hardware::hidl_vec<uint8_t> curPwd;
+    android::hardware::hidl_vec<uint8_t> curPwdHandle;
+    android::hardware::hidl_vec<uint8_t> curPwd;
 
-        if (currentPasswordHandle && currentPassword) {
-            if (hw_device) {
-                // Hidl Implementations expects passwordHandle to be in
-                // gatekeeper::password_handle_t format.
-                if (currentPasswordHandle->size() != sizeof(gatekeeper::password_handle_t)) {
-                    LOG(INFO) << "Password handle has wrong length";
-                    return GK_ERROR;
-                }
-            }
-            curPwdHandle.setToExternal(const_cast<uint8_t*>(currentPasswordHandle->data()),
-                                       currentPasswordHandle->size());
-            curPwd.setToExternal(const_cast<uint8_t*>(currentPassword->data()),
-                                 currentPassword->size());
-        }
-
-        android::hardware::hidl_vec<uint8_t> newPwd;
-        newPwd.setToExternal(const_cast<uint8_t*>(desiredPassword.data()), desiredPassword.size());
-
-        uint32_t hw_userId = adjust_userId(userId);
-        uint64_t secureUserId = 0;
-        if (aidl_hw_device) {
-            // AIDL gatekeeper service
-            AidlGatekeeperEnrollResp rsp;
-            auto result = aidl_hw_device->enroll(hw_userId, curPwdHandle, curPwd, newPwd, &rsp);
-            if (!result.isOk()) {
-                LOG(ERROR) << "enroll transaction failed";
+    if (currentPasswordHandle && currentPassword) {
+        if (hw_device) {
+            // Hidl Implementations expects passwordHandle to be in
+            // gatekeeper::password_handle_t format.
+            if (currentPasswordHandle->size() != sizeof(gatekeeper::password_handle_t)) {
+                LOG(INFO) << "Password handle has wrong length";
                 return GK_ERROR;
             }
-            if (rsp.statusCode >= AidlIGatekeeper::STATUS_OK) {
-                *gkResponse = GKResponse::ok({rsp.data.begin(), rsp.data.end()});
-                secureUserId = static_cast<uint64_t>(rsp.secureUserId);
-            } else if (rsp.statusCode == AidlIGatekeeper::ERROR_RETRY_TIMEOUT &&
-                       rsp.timeoutMs > 0) {
-                *gkResponse = GKResponse::retry(rsp.timeoutMs);
-            } else {
-                *gkResponse = GKResponse::error();
-            }
-        } else if (hw_device) {
-            // HIDL gatekeeper service
-            Return<void> hwRes = hw_device->enroll(
+        }
+        curPwdHandle.setToExternal(const_cast<uint8_t*>(currentPasswordHandle->data()),
+                                   currentPasswordHandle->size());
+        curPwd.setToExternal(const_cast<uint8_t*>(currentPassword->data()),
+                             currentPassword->size());
+    }
+
+    android::hardware::hidl_vec<uint8_t> newPwd;
+    newPwd.setToExternal(const_cast<uint8_t*>(desiredPassword.data()), desiredPassword.size());
+
+    uint32_t hw_userId = adjust_userId(userId);
+    uint64_t secureUserId = 0;
+    if (aidl_hw_device) {
+        // AIDL gatekeeper service
+        AidlGatekeeperEnrollResp rsp;
+        auto result = aidl_hw_device->enroll(hw_userId, curPwdHandle, curPwd, newPwd, &rsp);
+        if (!result.isOk()) {
+            LOG(ERROR) << "enroll transaction failed";
+            return GK_ERROR;
+        }
+        if (rsp.statusCode >= AidlIGatekeeper::STATUS_OK) {
+            *gkResponse = GKResponse::ok({rsp.data.begin(), rsp.data.end()});
+            secureUserId = static_cast<uint64_t>(rsp.secureUserId);
+        } else if (rsp.statusCode == AidlIGatekeeper::ERROR_RETRY_TIMEOUT && rsp.timeoutMs > 0) {
+            *gkResponse = GKResponse::retry(rsp.timeoutMs);
+        } else {
+            *gkResponse = GKResponse::error();
+        }
+    } else if (hw_device) {
+        // HIDL gatekeeper service
+        Return<void> hwRes = hw_device->enroll(
                 hw_userId, curPwdHandle, curPwd, newPwd,
                 [&gkResponse](const GatekeeperResponse& rsp) {
                     if (rsp.code >= GatekeeperStatusCode::STATUS_OK) {
@@ -247,110 +233,110 @@
                         *gkResponse = GKResponse::error();
                     }
                 });
-            if (!hwRes.isOk()) {
-                LOG(ERROR) << "enroll transaction failed";
+        if (!hwRes.isOk()) {
+            LOG(ERROR) << "enroll transaction failed";
+            return GK_ERROR;
+        }
+        if (gkResponse->response_code() == GKResponseCode::OK) {
+            if (gkResponse->payload().size() != sizeof(gatekeeper::password_handle_t)) {
+                LOG(ERROR) << "HAL returned password handle of invalid length "
+                           << gkResponse->payload().size();
                 return GK_ERROR;
             }
-            if (gkResponse->response_code() == GKResponseCode::OK) {
-                if (gkResponse->payload().size() != sizeof(gatekeeper::password_handle_t)) {
-                    LOG(ERROR) << "HAL returned password handle of invalid length "
-                               << gkResponse->payload().size();
-                    return GK_ERROR;
-                }
 
-                const gatekeeper::password_handle_t* handle =
+            const gatekeeper::password_handle_t* handle =
                     reinterpret_cast<const gatekeeper::password_handle_t*>(
-                        gkResponse->payload().data());
-                secureUserId = handle->user_id;
-            }
+                            gkResponse->payload().data());
+            secureUserId = handle->user_id;
         }
-
-        if (gkResponse->response_code() == GKResponseCode::OK && !gkResponse->should_reenroll()) {
-            store_sid(userId, secureUserId);
-
-            GKResponse verifyResponse;
-            // immediately verify this password so we don't ask the user to enter it again
-            // if they just created it.
-            auto status = verify(userId, gkResponse->payload(), desiredPassword, &verifyResponse);
-            if (!status.isOk() || verifyResponse.response_code() != GKResponseCode::OK) {
-                LOG(ERROR) << "Failed to verify password after enrolling";
-            }
-        }
-
-        return Status::ok();
     }
 
-    Status verify(int32_t userId, const ::std::vector<uint8_t>& enrolledPasswordHandle,
-                  const ::std::vector<uint8_t>& providedPassword, GKResponse* gkResponse) override {
-        return verifyChallenge(userId, 0 /* challenge */, enrolledPasswordHandle, providedPassword,
-                               gkResponse);
+    if (gkResponse->response_code() == GKResponseCode::OK && !gkResponse->should_reenroll()) {
+        store_sid(userId, secureUserId);
+
+        GKResponse verifyResponse;
+        // immediately verify this password so we don't ask the user to enter it again
+        // if they just created it.
+        auto status = verify(userId, gkResponse->payload(), desiredPassword, &verifyResponse);
+        if (!status.isOk() || verifyResponse.response_code() != GKResponseCode::OK) {
+            LOG(ERROR) << "Failed to verify password after enrolling";
+        }
     }
 
-    Status verifyChallenge(int32_t userId, int64_t challenge,
-                           const std::vector<uint8_t>& enrolledPasswordHandle,
-                           const std::vector<uint8_t>& providedPassword,
-                           GKResponse* gkResponse) override {
-        IPCThreadState* ipc = IPCThreadState::self();
-        const int calling_pid = ipc->getCallingPid();
-        const int calling_uid = ipc->getCallingUid();
-        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
+    return Status::ok();
+}
+
+Status GateKeeperProxy::verify(int32_t userId, const ::std::vector<uint8_t>& enrolledPasswordHandle,
+                               const ::std::vector<uint8_t>& providedPassword,
+                               GKResponse* gkResponse) {
+    return verifyChallenge(userId, 0 /* challenge */, enrolledPasswordHandle, providedPassword,
+                           gkResponse);
+}
+
+Status GateKeeperProxy::verifyChallenge(int32_t userId, int64_t challenge,
+                                        const std::vector<uint8_t>& enrolledPasswordHandle,
+                                        const std::vector<uint8_t>& providedPassword,
+                                        GKResponse* gkResponse) {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int calling_pid = ipc->getCallingPid();
+    const int calling_uid = ipc->getCallingUid();
+    if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
+        return GK_ERROR;
+    }
+
+    // can't verify if we're missing either param
+    if (enrolledPasswordHandle.size() == 0 || providedPassword.size() == 0) return GK_ERROR;
+
+    if (!aidl_hw_device && !hw_device) {
+        LOG(ERROR) << "has no HAL to talk to";
+        return GK_ERROR;
+    }
+
+    if (hw_device) {
+        // Hidl Implementations expects passwordHandle to be in gatekeeper::password_handle_t
+        if (enrolledPasswordHandle.size() != sizeof(gatekeeper::password_handle_t)) {
+            LOG(INFO) << "Password handle has wrong length";
             return GK_ERROR;
         }
+    }
 
-        // can't verify if we're missing either param
-        if (enrolledPasswordHandle.size() == 0 || providedPassword.size() == 0) return GK_ERROR;
+    uint32_t hw_userId = adjust_userId(userId);
+    android::hardware::hidl_vec<uint8_t> curPwdHandle;
+    curPwdHandle.setToExternal(const_cast<uint8_t*>(enrolledPasswordHandle.data()),
+                               enrolledPasswordHandle.size());
+    android::hardware::hidl_vec<uint8_t> enteredPwd;
+    enteredPwd.setToExternal(const_cast<uint8_t*>(providedPassword.data()),
+                             providedPassword.size());
 
-        if (!aidl_hw_device && !hw_device) {
-            LOG(ERROR) << "has no HAL to talk to";
+    uint64_t secureUserId = 0;
+    if (aidl_hw_device) {
+        // AIDL gatekeeper service
+        AidlGatekeeperVerifyResp rsp;
+        auto result = aidl_hw_device->verify(hw_userId, challenge, curPwdHandle, enteredPwd, &rsp);
+        if (!result.isOk()) {
+            LOG(ERROR) << "verify transaction failed";
             return GK_ERROR;
         }
-
-        if (hw_device) {
-            // Hidl Implementations expects passwordHandle to be in gatekeeper::password_handle_t
-            if (enrolledPasswordHandle.size() != sizeof(gatekeeper::password_handle_t)) {
-                LOG(INFO) << "Password handle has wrong length";
-                return GK_ERROR;
-            }
+        if (rsp.statusCode >= AidlIGatekeeper::STATUS_OK) {
+            secureUserId = rsp.hardwareAuthToken.userId;
+            // Serialize HardwareAuthToken to a vector as hw_auth_token_t.
+            *gkResponse = GKResponse::ok(
+                    authToken2AidlVec(rsp.hardwareAuthToken),
+                    rsp.statusCode == AidlIGatekeeper::STATUS_REENROLL /* reenroll */);
+        } else if (rsp.statusCode == AidlIGatekeeper::ERROR_RETRY_TIMEOUT) {
+            *gkResponse = GKResponse::retry(rsp.timeoutMs);
+        } else {
+            *gkResponse = GKResponse::error();
         }
-
-        uint32_t hw_userId = adjust_userId(userId);
-        android::hardware::hidl_vec<uint8_t> curPwdHandle;
-        curPwdHandle.setToExternal(const_cast<uint8_t*>(enrolledPasswordHandle.data()),
-                                   enrolledPasswordHandle.size());
-        android::hardware::hidl_vec<uint8_t> enteredPwd;
-        enteredPwd.setToExternal(const_cast<uint8_t*>(providedPassword.data()),
-                                 providedPassword.size());
-
-        uint64_t secureUserId = 0;
-        if (aidl_hw_device) {
-            // AIDL gatekeeper service
-            AidlGatekeeperVerifyResp rsp;
-            auto result =
-                aidl_hw_device->verify(hw_userId, challenge, curPwdHandle, enteredPwd, &rsp);
-            if (!result.isOk()) {
-                LOG(ERROR) << "verify transaction failed";
-                return GK_ERROR;
-            }
-            if (rsp.statusCode >= AidlIGatekeeper::STATUS_OK) {
-                secureUserId = rsp.hardwareAuthToken.userId;
-                // Serialize HardwareAuthToken to a vector as hw_auth_token_t.
-                *gkResponse = GKResponse::ok(authToken2AidlVec(rsp.hardwareAuthToken),
-                                             rsp.statusCode ==
-                                                 AidlIGatekeeper::STATUS_REENROLL /* reenroll */);
-            } else if (rsp.statusCode == AidlIGatekeeper::ERROR_RETRY_TIMEOUT) {
-                *gkResponse = GKResponse::retry(rsp.timeoutMs);
-            } else {
-                *gkResponse = GKResponse::error();
-            }
-        } else if (hw_device) {
-            // HIDL gatekeeper service
-            Return<void> hwRes = hw_device->verify(
+    } else if (hw_device) {
+        // HIDL gatekeeper service
+        Return<void> hwRes = hw_device->verify(
                 hw_userId, challenge, curPwdHandle, enteredPwd,
                 [&gkResponse](const GatekeeperResponse& rsp) {
                     if (rsp.code >= GatekeeperStatusCode::STATUS_OK) {
                         *gkResponse = GKResponse::ok(
-                            {rsp.data.begin(), rsp.data.end()},
-                            rsp.code == GatekeeperStatusCode::STATUS_REENROLL /* reenroll */);
+                                {rsp.data.begin(), rsp.data.end()},
+                                rsp.code == GatekeeperStatusCode::STATUS_REENROLL /* reenroll */);
                     } else if (rsp.code == GatekeeperStatusCode::ERROR_RETRY_TIMEOUT) {
                         *gkResponse = GKResponse::retry(rsp.timeout);
                     } else {
@@ -358,149 +344,110 @@
                     }
                 });
 
-            if (!hwRes.isOk()) {
-                LOG(ERROR) << "verify transaction failed";
-                return GK_ERROR;
-            }
-            const gatekeeper::password_handle_t* handle =
-                reinterpret_cast<const gatekeeper::password_handle_t*>(
-                    enrolledPasswordHandle.data());
-            secureUserId = handle->user_id;
+        if (!hwRes.isOk()) {
+            LOG(ERROR) << "verify transaction failed";
+            return GK_ERROR;
         }
+        const gatekeeper::password_handle_t* handle =
+                reinterpret_cast<const gatekeeper::password_handle_t*>(
+                        enrolledPasswordHandle.data());
+        secureUserId = handle->user_id;
+    }
 
-        if (gkResponse->response_code() == GKResponseCode::OK) {
-            if (gkResponse->payload().size() != 0) {
-                // try to connect to IKeystoreAuthorization AIDL service first.
-                AIBinder* authzAIBinder =
-                        AServiceManager_getService("android.security.authorization");
-                ::ndk::SpAIBinder authzBinder(authzAIBinder);
-                auto authzService = IKeystoreAuthorization::fromBinder(authzBinder);
-                if (authzService) {
-                    if (gkResponse->payload().size() != sizeof(hw_auth_token_t)) {
-                        LOG(ERROR) << "Incorrect size of AuthToken payload.";
-                        return GK_ERROR;
-                    }
-
-                    const hw_auth_token_t* hwAuthToken =
-                            reinterpret_cast<const hw_auth_token_t*>(gkResponse->payload().data());
-                    HardwareAuthToken authToken;
-
-                    authToken.timestamp.milliSeconds = betoh64(hwAuthToken->timestamp);
-                    authToken.challenge = hwAuthToken->challenge;
-                    authToken.userId = hwAuthToken->user_id;
-                    authToken.authenticatorId = hwAuthToken->authenticator_id;
-                    authToken.authenticatorType = static_cast<HardwareAuthenticatorType>(
-                            betoh32(hwAuthToken->authenticator_type));
-                    authToken.mac.assign(&hwAuthToken->hmac[0], &hwAuthToken->hmac[32]);
-                    auto result = authzService->addAuthToken(authToken);
-                    if (!result.isOk()) {
-                        LOG(ERROR) << "Failure in sending AuthToken to AuthorizationService.";
-                        return GK_ERROR;
-                    }
-                } else {
-                    LOG(ERROR) << "Cannot deliver auth token. Unable to communicate with "
-                                  "Keystore.";
+    if (gkResponse->response_code() == GKResponseCode::OK) {
+        if (gkResponse->payload().size() != 0) {
+            // try to connect to IKeystoreAuthorization AIDL service first.
+            AIBinder* authzAIBinder = AServiceManager_getService("android.security.authorization");
+            ::ndk::SpAIBinder authzBinder(authzAIBinder);
+            auto authzService = IKeystoreAuthorization::fromBinder(authzBinder);
+            if (authzService) {
+                if (gkResponse->payload().size() != sizeof(hw_auth_token_t)) {
+                    LOG(ERROR) << "Incorrect size of AuthToken payload.";
                     return GK_ERROR;
                 }
+
+                const hw_auth_token_t* hwAuthToken =
+                        reinterpret_cast<const hw_auth_token_t*>(gkResponse->payload().data());
+                HardwareAuthToken authToken;
+
+                authToken.timestamp.milliSeconds = betoh64(hwAuthToken->timestamp);
+                authToken.challenge = hwAuthToken->challenge;
+                authToken.userId = hwAuthToken->user_id;
+                authToken.authenticatorId = hwAuthToken->authenticator_id;
+                authToken.authenticatorType = static_cast<HardwareAuthenticatorType>(
+                        betoh32(hwAuthToken->authenticator_type));
+                authToken.mac.assign(&hwAuthToken->hmac[0], &hwAuthToken->hmac[32]);
+                auto result = authzService->addAuthToken(authToken);
+                if (!result.isOk()) {
+                    LOG(ERROR) << "Failure in sending AuthToken to AuthorizationService.";
+                    return GK_ERROR;
+                }
+            } else {
+                LOG(ERROR) << "Cannot deliver auth token. Unable to communicate with "
+                              "Keystore.";
+                return GK_ERROR;
             }
-
-            maybe_store_sid(userId, secureUserId);
         }
 
-        return Status::ok();
+        maybe_store_sid(userId, secureUserId);
     }
 
-    Status getSecureUserId(int32_t userId, int64_t* sid) override {
-        *sid = read_sid(userId);
-        return Status::ok();
-    }
-
-    Status clearSecureUserId(int32_t userId) override {
-        IPCThreadState* ipc = IPCThreadState::self();
-        const int calling_pid = ipc->getCallingPid();
-        const int calling_uid = ipc->getCallingUid();
-        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
-            ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
-            return Status::ok();
-        }
-        clear_sid(userId);
-
-        uint32_t hw_userId = adjust_userId(userId);
-        if (aidl_hw_device) {
-            aidl_hw_device->deleteUser(hw_userId);
-        } else if (hw_device) {
-            hw_device->deleteUser(hw_userId, [](const GatekeeperResponse&) {});
-        }
-        return Status::ok();
-    }
-
-    Status reportDeviceSetupComplete() override {
-        IPCThreadState* ipc = IPCThreadState::self();
-        const int calling_pid = ipc->getCallingPid();
-        const int calling_uid = ipc->getCallingUid();
-        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
-            ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
-            return Status::ok();
-        }
-
-        clear_state_if_needed();
-        return Status::ok();
-    }
-
-    status_t dump(int fd, const Vector<String16>&) override {
-        IPCThreadState* ipc = IPCThreadState::self();
-        const int pid = ipc->getCallingPid();
-        const int uid = ipc->getCallingUid();
-        if (!PermissionCache::checkPermission(DUMP_PERMISSION, pid, uid)) {
-            return PERMISSION_DENIED;
-        }
-
-        if (aidl_hw_device == nullptr && hw_device == nullptr) {
-            const char* result = "Device not available";
-            write(fd, result, strlen(result) + 1);
-        } else {
-            const char* result = "OK";
-            write(fd, result, strlen(result) + 1);
-        }
-
-        return OK;
-    }
-
-  private:
-    // AIDL gatekeeper service.
-    std::shared_ptr<AidlIGatekeeper> aidl_hw_device;
-    // HIDL gatekeeper service.
-    sp<IGatekeeper> hw_device;
-
-    bool clear_state_if_needed_done;
-    bool is_running_gsi;
-};
-}  // namespace android
-
-int main(int argc, char* argv[]) {
-    ALOGI("Starting gatekeeperd...");
-    if (argc < 2) {
-        ALOGE("A directory must be specified!");
-        return 1;
-    }
-    if (chdir(argv[1]) == -1) {
-        ALOGE("chdir: %s: %s", argv[1], strerror(errno));
-        return 1;
-    }
-
-    android::sp<android::IServiceManager> sm = android::defaultServiceManager();
-    android::sp<android::GateKeeperProxy> proxy = new android::GateKeeperProxy();
-    android::status_t ret =
-        sm->addService(android::String16("android.service.gatekeeper.IGateKeeperService"), proxy);
-    if (ret != android::OK) {
-        ALOGE("Couldn't register binder service!");
-        return -1;
-    }
-
-    /*
-     * We're the only thread in existence, so we're just going to process
-     * Binder transaction as a single-threaded program.
-     */
-    android::IPCThreadState::self()->joinThreadPool();
-    return 0;
+    return Status::ok();
 }
+
+Status GateKeeperProxy::getSecureUserId(int32_t userId, int64_t* sid) {
+    *sid = read_sid(userId);
+    return Status::ok();
+}
+
+Status GateKeeperProxy::clearSecureUserId(int32_t userId) {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int calling_pid = ipc->getCallingPid();
+    const int calling_uid = ipc->getCallingUid();
+    if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
+        ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
+        return Status::ok();
+    }
+    clear_sid(userId);
+
+    uint32_t hw_userId = adjust_userId(userId);
+    if (aidl_hw_device) {
+        aidl_hw_device->deleteUser(hw_userId);
+    } else if (hw_device) {
+        hw_device->deleteUser(hw_userId, [](const GatekeeperResponse&) {});
+    }
+    return Status::ok();
+}
+
+Status GateKeeperProxy::reportDeviceSetupComplete() {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int calling_pid = ipc->getCallingPid();
+    const int calling_uid = ipc->getCallingUid();
+    if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
+        ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
+        return Status::ok();
+    }
+
+    clear_state_if_needed();
+    return Status::ok();
+}
+
+status_t GateKeeperProxy::dump(int fd, const Vector<String16>&) {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int pid = ipc->getCallingPid();
+    const int uid = ipc->getCallingUid();
+    if (!PermissionCache::checkPermission(DUMP_PERMISSION, pid, uid)) {
+        return PERMISSION_DENIED;
+    }
+
+    if (aidl_hw_device == nullptr && hw_device == nullptr) {
+        const char* result = "Device not available";
+        write(fd, result, strlen(result) + 1);
+    } else {
+        const char* result = "OK";
+        write(fd, result, strlen(result) + 1);
+    }
+
+    return OK;
+}
+}  // namespace android
diff --git a/gatekeeperd/gatekeeperd.h b/gatekeeperd/gatekeeperd.h
new file mode 100644
index 0000000..29873da
--- /dev/null
+++ b/gatekeeperd/gatekeeperd.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2023 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 <aidl/android/hardware/gatekeeper/IGatekeeper.h>
+#include <android/hardware/gatekeeper/1.0/IGatekeeper.h>
+#include <android/service/gatekeeper/BnGateKeeperService.h>
+#include <gatekeeper/GateKeeperResponse.h>
+
+using ::android::hardware::gatekeeper::V1_0::IGatekeeper;
+using AidlIGatekeeper = ::aidl::android::hardware::gatekeeper::IGatekeeper;
+using ::android::binder::Status;
+using ::android::service::gatekeeper::BnGateKeeperService;
+using GKResponse = ::android::service::gatekeeper::GateKeeperResponse;
+
+namespace android {
+
+class GateKeeperProxy : public BnGateKeeperService {
+  public:
+    GateKeeperProxy();
+
+    virtual ~GateKeeperProxy() {}
+
+    void store_sid(uint32_t userId, uint64_t sid);
+
+    void clear_state_if_needed();
+
+    bool mark_cold_boot();
+
+    void maybe_store_sid(uint32_t userId, uint64_t sid);
+
+    uint64_t read_sid(uint32_t userId);
+
+    void clear_sid(uint32_t userId);
+
+    // This should only be called on userIds being passed to the GateKeeper HAL. It ensures that
+    // secure storage shared across a GSI image and a host image will not overlap.
+    uint32_t adjust_userId(uint32_t userId);
+
+#define GK_ERROR *gkResponse = GKResponse::error(), Status::ok()
+
+    Status enroll(int32_t userId, const std::optional<std::vector<uint8_t>>& currentPasswordHandle,
+                  const std::optional<std::vector<uint8_t>>& currentPassword,
+                  const std::vector<uint8_t>& desiredPassword, GKResponse* gkResponse) override;
+
+    Status verify(int32_t userId, const ::std::vector<uint8_t>& enrolledPasswordHandle,
+                  const ::std::vector<uint8_t>& providedPassword, GKResponse* gkResponse) override;
+
+    Status verifyChallenge(int32_t userId, int64_t challenge,
+                           const std::vector<uint8_t>& enrolledPasswordHandle,
+                           const std::vector<uint8_t>& providedPassword,
+                           GKResponse* gkResponse) override;
+
+    Status getSecureUserId(int32_t userId, int64_t* sid) override;
+
+    Status clearSecureUserId(int32_t userId) override;
+
+    Status reportDeviceSetupComplete() override;
+
+    status_t dump(int fd, const Vector<String16>&) override;
+
+  private:
+    // AIDL gatekeeper service.
+    std::shared_ptr<AidlIGatekeeper> aidl_hw_device;
+    // HIDL gatekeeper service.
+    sp<IGatekeeper> hw_device;
+
+    bool clear_state_if_needed_done;
+    bool is_running_gsi;
+};
+}  // namespace android
diff --git a/gatekeeperd/main.cpp b/gatekeeperd/main.cpp
new file mode 100644
index 0000000..a01f9de
--- /dev/null
+++ b/gatekeeperd/main.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2023 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 <binder/IPCThreadState.h>
+#include <binder/IServiceManager.h>
+
+#include <log/log.h>
+
+#include "gatekeeperd.h"
+
+int main(int argc, char* argv[]) {
+    ALOGI("Starting gatekeeperd...");
+    if (argc < 2) {
+        ALOGE("A directory must be specified!");
+        return 1;
+    }
+    if (chdir(argv[1]) == -1) {
+        ALOGE("chdir: %s: %s", argv[1], strerror(errno));
+        return 1;
+    }
+
+    android::sp<android::IServiceManager> sm = android::defaultServiceManager();
+    android::sp<android::GateKeeperProxy> proxy = new android::GateKeeperProxy();
+    android::status_t ret = sm->addService(
+            android::String16("android.service.gatekeeper.IGateKeeperService"), proxy);
+    if (ret != android::OK) {
+        ALOGE("Couldn't register binder service!");
+        return 1;
+    }
+
+    /*
+     * We're the only thread in existence, so we're just going to process
+     * Binder transaction as a single-threaded program.
+     */
+    android::IPCThreadState::self()->joinThreadPool();
+    return 1;
+}
diff --git a/healthd/BatteryMonitor.cpp b/healthd/BatteryMonitor.cpp
index 66e1e63..f68d65a 100644
--- a/healthd/BatteryMonitor.cpp
+++ b/healthd/BatteryMonitor.cpp
@@ -242,6 +242,8 @@
         value = BatteryHealth::DEAD;
     else if (status == BatteryMonitor::BH_FAILED)
         value = BatteryHealth::UNSPECIFIED_FAILURE;
+    else if (status == BatteryMonitor::BH_NOT_AVAILABLE)
+        value = BatteryHealth::NOT_AVAILABLE;
     else
         value = BatteryHealth::UNKNOWN;
 
diff --git a/healthd/include/healthd/BatteryMonitor.h b/healthd/include/healthd/BatteryMonitor.h
index 7b4f46c..a4c013b 100644
--- a/healthd/include/healthd/BatteryMonitor.h
+++ b/healthd/include/healthd/BatteryMonitor.h
@@ -62,6 +62,7 @@
         BH_MARGINAL,
         BH_NEEDS_REPLACEMENT,
         BH_FAILED,
+        BH_NOT_AVAILABLE,
     };
 
     BatteryMonitor();
diff --git a/init/init_test.cpp b/init/init_test.cpp
index 0fc3ffc..7e8513b 100644
--- a/init/init_test.cpp
+++ b/init/init_test.cpp
@@ -180,9 +180,11 @@
     std::string init_script = R"init(
 service A something
     class first
+    user nobody
 
 service A something
     class second
+    user nobody
     override
 
 )init";
@@ -610,6 +612,31 @@
     EXPECT_EQ(2, num_executed);
 }
 
+TEST(init, RejectsNoUserStartingInV) {
+    std::string init_script =
+            R"init(
+service A something
+    class first
+)init";
+
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    ASSERT_TRUE(android::base::WriteStringToFd(init_script, tf.fd));
+
+    ServiceList service_list;
+    Parser parser;
+    parser.AddSectionParser("service",
+                            std::make_unique<ServiceParser>(&service_list, nullptr, std::nullopt));
+
+    ASSERT_TRUE(parser.ParseConfig(tf.path));
+
+    if (GetIntProperty("ro.vendor.api_level", 0) > __ANDROID_API_U__) {
+        ASSERT_EQ(1u, parser.parse_error_count());
+    } else {
+        ASSERT_EQ(0u, parser.parse_error_count());
+    }
+}
+
 TEST(init, RejectsCriticalAndOneshotService) {
     if (GetIntProperty("ro.product.first_api_level", 10000) < 30) {
         GTEST_SKIP() << "Test only valid for devices launching with R or later";
@@ -619,6 +646,7 @@
             R"init(
 service A something
   class first
+  user root
   critical
   oneshot
 )init";
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index d89664c..d46e1f7 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -25,6 +25,7 @@
 
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
+#include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <hidl-util/FQName.h>
 #include <processgroup/processgroup.h>
@@ -678,8 +679,13 @@
     }
 
     if (service_->proc_attr_.parsed_uid == std::nullopt) {
-        LOG(WARNING) << "No user specified for service '" << service_->name()
-                     << "'. Defaults to root.";
+        if (android::base::GetIntProperty("ro.vendor.api_level", 0) > __ANDROID_API_U__) {
+            return Error() << "No user specified for service '" << service_->name()
+                           << "'. Defaults to root.";
+        } else {
+            LOG(WARNING) << "No user specified for service '" << service_->name()
+                         << "'. Defaults to root.";
+        }
     }
 
     if (interface_inheritance_hierarchy_) {
diff --git a/libprocessgroup/include/processgroup/processgroup.h b/libprocessgroup/include/processgroup/processgroup.h
index 48bc0b7..dbaeb93 100644
--- a/libprocessgroup/include/processgroup/processgroup.h
+++ b/libprocessgroup/include/processgroup/processgroup.h
@@ -96,6 +96,10 @@
 // Returns false in case of error, true in case of success
 bool getAttributePathForTask(const std::string& attr_name, int tid, std::string* path);
 
+// Check if a profile can be applied without failing.
+// Returns true if it can be applied without failing, false otherwise
+bool isProfileValidForProcess(const std::string& profile_name, int uid, int pid);
+
 #endif // __ANDROID_VNDK__
 
 __END_DECLS
diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index a021594..1f29040 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -216,7 +216,6 @@
 static int RemoveProcessGroup(const char* cgroup, uid_t uid, int pid, unsigned int retries) {
     int ret = 0;
     auto uid_pid_path = ConvertUidPidToPath(cgroup, uid, pid);
-    auto uid_path = ConvertUidToPath(cgroup, uid);
 
     while (retries--) {
         ret = rmdir(uid_pid_path.c_str());
@@ -657,3 +656,13 @@
 bool getAttributePathForTask(const std::string& attr_name, int tid, std::string* path) {
     return CgroupGetAttributePathForTask(attr_name, tid, path);
 }
+
+bool isProfileValidForProcess(const std::string& profile_name, int uid, int pid) {
+    const TaskProfile* tp = TaskProfiles::GetInstance().GetProfile(profile_name);
+
+    if (tp == nullptr) {
+        return false;
+    }
+
+    return tp->IsValidForProcess(uid, pid);
+}
\ No newline at end of file
diff --git a/libprocessgroup/task_profiles.cpp b/libprocessgroup/task_profiles.cpp
index 1731828..44dba2a 100644
--- a/libprocessgroup/task_profiles.cpp
+++ b/libprocessgroup/task_profiles.cpp
@@ -259,6 +259,31 @@
     return true;
 }
 
+bool SetAttributeAction::IsValidForProcess(uid_t, pid_t pid) const {
+    return IsValidForTask(pid);
+}
+
+bool SetAttributeAction::IsValidForTask(int tid) const {
+    std::string path;
+
+    if (!attribute_->GetPathForTask(tid, &path)) {
+        return false;
+    }
+
+    if (!access(path.c_str(), W_OK)) {
+        // operation will succeed
+        return true;
+    }
+
+    if (!access(path.c_str(), F_OK)) {
+        // file exists but not writable
+        return false;
+    }
+
+    // file does not exist, ignore if optional
+    return optional_;
+}
+
 SetCgroupAction::SetCgroupAction(const CgroupController& c, const std::string& p)
     : controller_(c), path_(p) {
     FdCacheHelper::Init(controller_.GetTasksFilePath(path_), fd_[ProfileAction::RCT_TASK]);
@@ -396,6 +421,39 @@
     FdCacheHelper::Drop(fd_[cache_type]);
 }
 
+bool SetCgroupAction::IsValidForProcess(uid_t uid, pid_t pid) const {
+    std::lock_guard<std::mutex> lock(fd_mutex_);
+    if (FdCacheHelper::IsCached(fd_[ProfileAction::RCT_PROCESS])) {
+        return true;
+    }
+
+    if (fd_[ProfileAction::RCT_PROCESS] == FdCacheHelper::FDS_INACCESSIBLE) {
+        return false;
+    }
+
+    std::string procs_path = controller()->GetProcsFilePath(path_, uid, pid);
+    return access(procs_path.c_str(), W_OK) == 0;
+}
+
+bool SetCgroupAction::IsValidForTask(int) const {
+    std::lock_guard<std::mutex> lock(fd_mutex_);
+    if (FdCacheHelper::IsCached(fd_[ProfileAction::RCT_TASK])) {
+        return true;
+    }
+
+    if (fd_[ProfileAction::RCT_TASK] == FdCacheHelper::FDS_INACCESSIBLE) {
+        return false;
+    }
+
+    if (fd_[ProfileAction::RCT_TASK] == FdCacheHelper::FDS_APP_DEPENDENT) {
+        // application-dependent path can't be used with tid
+        return false;
+    }
+
+    std::string tasks_path = controller()->GetTasksFilePath(path_);
+    return access(tasks_path.c_str(), W_OK) == 0;
+}
+
 WriteFileAction::WriteFileAction(const std::string& task_path, const std::string& proc_path,
                                  const std::string& value, bool logfailures)
     : task_path_(task_path), proc_path_(proc_path), value_(value), logfailures_(logfailures) {
@@ -532,6 +590,37 @@
     FdCacheHelper::Drop(fd_[cache_type]);
 }
 
+bool WriteFileAction::IsValidForProcess(uid_t, pid_t) const {
+    std::lock_guard<std::mutex> lock(fd_mutex_);
+    if (FdCacheHelper::IsCached(fd_[ProfileAction::RCT_PROCESS])) {
+        return true;
+    }
+
+    if (fd_[ProfileAction::RCT_PROCESS] == FdCacheHelper::FDS_INACCESSIBLE) {
+        return false;
+    }
+
+    return access(proc_path_.empty() ? task_path_.c_str() : proc_path_.c_str(), W_OK) == 0;
+}
+
+bool WriteFileAction::IsValidForTask(int) const {
+    std::lock_guard<std::mutex> lock(fd_mutex_);
+    if (FdCacheHelper::IsCached(fd_[ProfileAction::RCT_TASK])) {
+        return true;
+    }
+
+    if (fd_[ProfileAction::RCT_TASK] == FdCacheHelper::FDS_INACCESSIBLE) {
+        return false;
+    }
+
+    if (fd_[ProfileAction::RCT_TASK] == FdCacheHelper::FDS_APP_DEPENDENT) {
+        // application-dependent path can't be used with tid
+        return false;
+    }
+
+    return access(task_path_.c_str(), W_OK) == 0;
+}
+
 bool ApplyProfileAction::ExecuteForProcess(uid_t uid, pid_t pid) const {
     for (const auto& profile : profiles_) {
         profile->ExecuteForProcess(uid, pid);
@@ -558,6 +647,24 @@
     }
 }
 
+bool ApplyProfileAction::IsValidForProcess(uid_t uid, pid_t pid) const {
+    for (const auto& profile : profiles_) {
+        if (!profile->IsValidForProcess(uid, pid)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool ApplyProfileAction::IsValidForTask(int tid) const {
+    for (const auto& profile : profiles_) {
+        if (!profile->IsValidForTask(tid)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 void TaskProfile::MoveTo(TaskProfile* profile) {
     profile->elements_ = std::move(elements_);
     profile->res_cached_ = res_cached_;
@@ -620,6 +727,20 @@
     res_cached_ = false;
 }
 
+bool TaskProfile::IsValidForProcess(uid_t uid, pid_t pid) const {
+    for (const auto& element : elements_) {
+        if (!element->IsValidForProcess(uid, pid)) return false;
+    }
+    return true;
+}
+
+bool TaskProfile::IsValidForTask(int tid) const {
+    for (const auto& element : elements_) {
+        if (!element->IsValidForTask(tid)) return false;
+    }
+    return true;
+}
+
 void TaskProfiles::DropResourceCaching(ProfileAction::ResourceCacheType cache_type) const {
     for (auto& iter : profiles_) {
         iter.second->DropResourceCaching(cache_type);
diff --git a/libprocessgroup/task_profiles.h b/libprocessgroup/task_profiles.h
index a8ecb87..a62c5b0 100644
--- a/libprocessgroup/task_profiles.h
+++ b/libprocessgroup/task_profiles.h
@@ -72,12 +72,14 @@
     virtual const char* Name() const = 0;
 
     // Default implementations will fail
-    virtual bool ExecuteForProcess(uid_t, pid_t) const { return false; };
-    virtual bool ExecuteForTask(int) const { return false; };
-    virtual bool ExecuteForUID(uid_t) const { return false; };
+    virtual bool ExecuteForProcess(uid_t, pid_t) const { return false; }
+    virtual bool ExecuteForTask(int) const { return false; }
+    virtual bool ExecuteForUID(uid_t) const { return false; }
 
     virtual void EnableResourceCaching(ResourceCacheType) {}
     virtual void DropResourceCaching(ResourceCacheType) {}
+    virtual bool IsValidForProcess(uid_t uid, pid_t pid) const { return false; }
+    virtual bool IsValidForTask(int tid) const { return false; }
 
   protected:
     enum CacheUseResult { SUCCESS, FAIL, UNUSED };
@@ -103,6 +105,8 @@
 
     const char* Name() const override { return "SetTimerSlack"; }
     bool ExecuteForTask(int tid) const override;
+    bool IsValidForProcess(uid_t uid, pid_t pid) const override { return true; }
+    bool IsValidForTask(int tid) const override { return true; }
 
   private:
     unsigned long slack_;
@@ -120,6 +124,8 @@
     bool ExecuteForProcess(uid_t uid, pid_t pid) const override;
     bool ExecuteForTask(int tid) const override;
     bool ExecuteForUID(uid_t uid) const override;
+    bool IsValidForProcess(uid_t uid, pid_t pid) const override;
+    bool IsValidForTask(int tid) const override;
 
   private:
     const IProfileAttribute* attribute_;
@@ -137,6 +143,8 @@
     bool ExecuteForTask(int tid) const override;
     void EnableResourceCaching(ResourceCacheType cache_type) override;
     void DropResourceCaching(ResourceCacheType cache_type) override;
+    bool IsValidForProcess(uid_t uid, pid_t pid) const override;
+    bool IsValidForTask(int tid) const override;
 
     const CgroupController* controller() const { return &controller_; }
 
@@ -161,6 +169,8 @@
     bool ExecuteForTask(int tid) const override;
     void EnableResourceCaching(ResourceCacheType cache_type) override;
     void DropResourceCaching(ResourceCacheType cache_type) override;
+    bool IsValidForProcess(uid_t uid, pid_t pid) const override;
+    bool IsValidForTask(int tid) const override;
 
   private:
     std::string task_path_, proc_path_, value_;
@@ -186,6 +196,8 @@
     bool ExecuteForUID(uid_t uid) const;
     void EnableResourceCaching(ProfileAction::ResourceCacheType cache_type);
     void DropResourceCaching(ProfileAction::ResourceCacheType cache_type);
+    bool IsValidForProcess(uid_t uid, pid_t pid) const;
+    bool IsValidForTask(int tid) const;
 
   private:
     const std::string name_;
@@ -204,6 +216,8 @@
     bool ExecuteForTask(int tid) const override;
     void EnableResourceCaching(ProfileAction::ResourceCacheType cache_type) override;
     void DropResourceCaching(ProfileAction::ResourceCacheType cache_type) override;
+    bool IsValidForProcess(uid_t uid, pid_t pid) const override;
+    bool IsValidForTask(int tid) const override;
 
   private:
     std::vector<std::shared_ptr<TaskProfile>> profiles_;
diff --git a/libprocessgroup/task_profiles_test.cpp b/libprocessgroup/task_profiles_test.cpp
index 6a5b48b..eadbe76 100644
--- a/libprocessgroup/task_profiles_test.cpp
+++ b/libprocessgroup/task_profiles_test.cpp
@@ -175,6 +175,32 @@
     }
 }
 
+class TaskProfileFixture : public TestWithParam<TestParam> {
+  public:
+    ~TaskProfileFixture() = default;
+};
+
+TEST_P(TaskProfileFixture, TaskProfile) {
+    // Treehugger runs host tests inside a container without cgroupv2 support.
+    if (!IsCgroupV2MountedRw()) {
+        GTEST_SKIP();
+        return;
+    }
+    const TestParam params = GetParam();
+    ProfileAttributeMock pa(params.attr_name);
+    // Test simple profile with one action
+    std::shared_ptr<TaskProfile> tp = std::make_shared<TaskProfile>("test_profile");
+    tp->Add(std::make_unique<SetAttributeAction>(&pa, params.attr_value, params.optional_attr));
+    EXPECT_EQ(tp->IsValidForProcess(getuid(), getpid()), params.result);
+    EXPECT_EQ(tp->IsValidForTask(getpid()), params.result);
+    // Test aggregate profile
+    TaskProfile tp2("meta_profile");
+    std::vector<std::shared_ptr<TaskProfile>> profiles = {tp};
+    tp2.Add(std::make_unique<ApplyProfileAction>(profiles));
+    EXPECT_EQ(tp2.IsValidForProcess(getuid(), getpid()), params.result);
+    EXPECT_EQ(tp2.IsValidForTask(getpid()), params.result);
+}
+
 // Test the four combinations of optional_attr {false, true} and cgroup attribute { does not exist,
 // exists }.
 INSTANTIATE_TEST_SUITE_P(
@@ -215,4 +241,28 @@
                         .log_prefix = "Failed to write",
                         .log_suffix = geteuid() == 0 ? "Invalid argument" : "Permission denied"}));
 
+// Test TaskProfile IsValid calls.
+INSTANTIATE_TEST_SUITE_P(
+        TaskProfileTestSuite, TaskProfileFixture,
+        Values(
+                // Test operating on non-existing cgroup attribute fails.
+                TestParam{.attr_name = "no-such-attribute",
+                          .attr_value = ".",
+                          .optional_attr = false,
+                          .result = false},
+                // Test operating on optional non-existing cgroup attribute succeeds.
+                TestParam{.attr_name = "no-such-attribute",
+                          .attr_value = ".",
+                          .optional_attr = true,
+                          .result = true},
+                // Test operating on existing cgroup attribute succeeds.
+                TestParam{.attr_name = "cgroup.procs",
+                          .attr_value = ".",
+                          .optional_attr = false,
+                          .result = true},
+                // Test operating on optional existing cgroup attribute succeeds.
+                TestParam{.attr_name = "cgroup.procs",
+                          .attr_value = ".",
+                          .optional_attr = true,
+                          .result = true}));
 }  // namespace
diff --git a/rootdir/init.usb.rc b/rootdir/init.usb.rc
index 0730cce..dde784e 100644
--- a/rootdir/init.usb.rc
+++ b/rootdir/init.usb.rc
@@ -18,6 +18,7 @@
     disabled
     updatable
     seclabel u:r:adbd:s0
+    user root
 
 on property:vendor.sys.usb.adb.disabled=*
     setprop sys.usb.adb.disabled ${vendor.sys.usb.adb.disabled}
diff --git a/rootdir/ramdisk_node_list b/rootdir/ramdisk_node_list
index d3ab8a6..4f45faa 100644
--- a/rootdir/ramdisk_node_list
+++ b/rootdir/ramdisk_node_list
@@ -1,3 +1,4 @@
 dir dev 0755 0 0
 nod dev/null 0600 0 0 c 1 3
 nod dev/console 0600 0 0 c 5 1
+nod dev/urandom 0600 0 0 c 1 9
diff --git a/storaged/Android.bp b/storaged/Android.bp
index c3447d2..04f5d79 100644
--- a/storaged/Android.bp
+++ b/storaged/Android.bp
@@ -136,3 +136,27 @@
     ],
     path: "binder",
 }
+
+cc_fuzz {
+    name: "storaged_service_fuzzer",
+    defaults: [
+        "storaged_defaults",
+        "service_fuzzer_defaults",
+    ],
+    srcs: ["tests/fuzzers/storaged_service_fuzzer.cpp"],
+    static_libs: [
+        "libstoraged",
+    ],
+}
+
+cc_fuzz {
+    name: "storaged_private_service_fuzzer",
+    defaults: [
+        "storaged_defaults",
+        "service_fuzzer_defaults",
+    ],
+    srcs: ["tests/fuzzers/storaged_private_service_fuzzer.cpp"],
+    static_libs: [
+        "libstoraged",
+    ],
+}
\ No newline at end of file
diff --git a/storaged/include/storaged_service.h b/storaged/include/storaged_service.h
index 7ec6864..bf7af80 100644
--- a/storaged/include/storaged_service.h
+++ b/storaged/include/storaged_service.h
@@ -28,6 +28,7 @@
 using namespace android::os;
 using namespace android::os::storaged;
 
+namespace android {
 class StoragedService : public BinderService<StoragedService>, public BnStoraged {
 private:
     void dumpUidRecordsDebug(int fd, const vector<struct uid_record>& entries);
@@ -53,4 +54,5 @@
 
 sp<IStoragedPrivate> get_storaged_pri_service();
 
+}  // namespace android
 #endif /* _STORAGED_SERVICE_H_ */
\ No newline at end of file
diff --git a/storaged/storaged_service.cpp b/storaged/storaged_service.cpp
index 45f1d4d..00d36d7 100644
--- a/storaged/storaged_service.cpp
+++ b/storaged/storaged_service.cpp
@@ -38,6 +38,7 @@
 
 extern sp<storaged_t> storaged_sp;
 
+namespace android {
 status_t StoragedService::start() {
     return BinderService<StoragedService>::publish();
 }
@@ -218,3 +219,4 @@
 
     return interface_cast<IStoragedPrivate>(binder);
 }
+}  // namespace android
\ No newline at end of file
diff --git a/storaged/tests/fuzzers/storaged_private_service_fuzzer.cpp b/storaged/tests/fuzzers/storaged_private_service_fuzzer.cpp
new file mode 100644
index 0000000..82eb796
--- /dev/null
+++ b/storaged/tests/fuzzers/storaged_private_service_fuzzer.cpp
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2023 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 <fuzzbinder/libbinder_driver.h>
+
+#include <storaged.h>
+#include <storaged_service.h>
+
+sp<storaged_t> storaged_sp;
+
+extern "C" int LLVMFuzzerInitialize(int /**argc*/, char /****argv*/) {
+    storaged_sp = new storaged_t();
+    storaged_sp->init();
+    return 0;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    auto storagedPrivateService = new StoragedPrivateService();
+    fuzzService(storagedPrivateService, FuzzedDataProvider(data, size));
+    return 0;
+}
\ No newline at end of file
diff --git a/storaged/tests/fuzzers/storaged_service_fuzzer.cpp b/storaged/tests/fuzzers/storaged_service_fuzzer.cpp
new file mode 100644
index 0000000..d11ecc3
--- /dev/null
+++ b/storaged/tests/fuzzers/storaged_service_fuzzer.cpp
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2023 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 <fuzzbinder/libbinder_driver.h>
+
+#include <storaged.h>
+#include <storaged_service.h>
+
+sp<storaged_t> storaged_sp;
+
+extern "C" int LLVMFuzzerInitialize(int /**argc*/, char /****argv*/) {
+    storaged_sp = new storaged_t();
+    storaged_sp->init();
+    return 0;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    auto storagedService = new StoragedService();
+    fuzzService(storagedService, FuzzedDataProvider(data, size));
+    return 0;
+}
\ No newline at end of file