52 files changed, 2383 insertions, 344 deletions

diff --git a/Android.mk b/Android.mk
index 55ec38799..4f85ce5dd 100644
--- a/Android.mk
+++ b/Android.mk
@@ -211,7 +211,7 @@ include $(BUILD_EXECUTABLE)
 include \
     $(LOCAL_PATH)/boot_control/Android.mk \
     $(LOCAL_PATH)/minui/Android.mk \
-    $(LOCAL_PATH)/sample_updater/Android.mk \
     $(LOCAL_PATH)/tests/Android.mk \
     $(LOCAL_PATH)/tools/Android.mk \
     $(LOCAL_PATH)/updater/Android.mk \
+    $(LOCAL_PATH)/updater_sample/Android.mk \
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 878651c8e..108429193 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -7,5 +7,5 @@ clang_format = --commit ${PREUPLOAD_COMMIT} --style file --extensions c,h,cc,cpp
 
 [Hook Scripts]
 checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
-                  -fw sample_updater/
+                  -fw updater_sample/
 
diff --git a/adb_install.cpp b/adb_install.cpp
index ac0130651..4ee5333c7 100644
--- a/adb_install.cpp
+++ b/adb_install.cpp
@@ -70,7 +70,7 @@ static void maybe_restart_adbd() {
   }
 }
 
-int apply_from_adb(bool* wipe_cache, const char* install_file) {
+int apply_from_adb(bool* wipe_cache) {
   modified_flash = true;
 
   stop_adbd();
@@ -113,7 +113,7 @@ int apply_from_adb(bool* wipe_cache, const char* install_file) {
         break;
       }
     }
-    result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache, install_file, false, 0);
+    result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache, false, 0);
     break;
   }
 
diff --git a/adb_install.h b/adb_install.h
index e654c893d..cc3ca267b 100644
--- a/adb_install.h
+++ b/adb_install.h
@@ -17,6 +17,6 @@
 #ifndef _ADB_INSTALL_H
 #define _ADB_INSTALL_H
 
-int apply_from_adb(bool* wipe_cache, const char* install_file);
+int apply_from_adb(bool* wipe_cache);
 
 #endif
diff --git a/applypatch/applypatch.cpp b/applypatch/applypatch.cpp
index 7104abd67..39b8030d9 100644
--- a/applypatch/applypatch.cpp
+++ b/applypatch/applypatch.cpp
@@ -40,7 +40,7 @@
 
 #include "edify/expr.h"
 #include "otafault/ota_io.h"
-#include "otautil/cache_location.h"
+#include "otautil/paths.h"
 #include "otautil/print_sha1.h"
 
 static int LoadPartitionContents(const std::string& filename, FileContents* file);
@@ -403,7 +403,7 @@ int applypatch_check(const char* filename, const std::vector<std::string>& patch
     // If the source file is missing or corrupted, it might be because we were killed in the middle
     // of patching it.  A copy of it should have been made in cache_temp_source.  If that file
     // exists and matches the sha1 we're looking for, the check still passes.
-    if (LoadFileContents(CacheLocation::location().cache_temp_source().c_str(), &file) != 0) {
+    if (LoadFileContents(Paths::Get().cache_temp_source().c_str(), &file) != 0) {
       printf("failed to load cache file\n");
       return 1;
     }
@@ -525,7 +525,7 @@ int applypatch(const char* source_filename, const char* target_filename,
   printf("source file is bad; trying copy\n");
 
   FileContents copy_file;
-  if (LoadFileContents(CacheLocation::location().cache_temp_source().c_str(), &copy_file) < 0) {
+  if (LoadFileContents(Paths::Get().cache_temp_source().c_str(), &copy_file) < 0) {
     printf("failed to read copy file\n");
     return 1;
   }
@@ -620,7 +620,7 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
     printf("not enough free space on /cache\n");
     return 1;
   }
-  if (SaveFileContents(CacheLocation::location().cache_temp_source().c_str(), &source_file) < 0) {
+  if (SaveFileContents(Paths::Get().cache_temp_source().c_str(), &source_file) < 0) {
     printf("failed to back up source file\n");
     return 1;
   }
@@ -630,6 +630,11 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
   SHA_CTX ctx;
   SHA1_Init(&ctx);
   SinkFn sink = [&memory_sink_str, &ctx](const unsigned char* data, size_t len) {
+    if (len != 0) {
+      uint8_t digest[SHA_DIGEST_LENGTH];
+      SHA1(data, len, digest);
+      LOG(DEBUG) << "Appending " << len << " bytes data, sha1: " << short_sha1(digest);
+    }
     SHA1_Update(&ctx, data, len);
     memory_sink_str.append(reinterpret_cast<const char*>(data), len);
     return len;
@@ -680,7 +685,7 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
   }
 
   // Delete the backup copy of the source.
-  unlink(CacheLocation::location().cache_temp_source().c_str());
+  unlink(Paths::Get().cache_temp_source().c_str());
 
   // Success!
   return 0;
diff --git a/applypatch/freecache.cpp b/applypatch/freecache.cpp
index cfab0f6db..dbd4b72b1 100644
--- a/applypatch/freecache.cpp
+++ b/applypatch/freecache.cpp
@@ -38,7 +38,7 @@
 #include <android-base/strings.h>
 
 #include "applypatch/applypatch.h"
-#include "otautil/cache_location.h"
+#include "otautil/paths.h"
 
 static int EliminateOpenFiles(const std::string& dirname, std::set<std::string>* files) {
   std::unique_ptr<DIR, decltype(&closedir)> d(opendir("/proc"), closedir);
@@ -95,7 +95,7 @@ static std::vector<std::string> FindExpendableFiles(
 
     // We can't delete cache_temp_source; if it's there we might have restarted during
     // installation and could be depending on it to be there.
-    if (path == CacheLocation::location().cache_temp_source()) {
+    if (path == Paths::Get().cache_temp_source()) {
       continue;
     }
 
@@ -142,7 +142,7 @@ int MakeFreeSpaceOnCache(size_t bytes_needed) {
   return 0;
 #endif
 
-  std::vector<std::string> dirs = { "/cache", CacheLocation::location().cache_log_directory() };
+  std::vector<std::string> dirs = { "/cache", Paths::Get().cache_log_directory() };
   for (const auto& dirname : dirs) {
     if (RemoveFilesInDirectory(bytes_needed, dirname, FreeSpaceForFile)) {
       return 0;
@@ -172,7 +172,7 @@ bool RemoveFilesInDirectory(size_t bytes_needed, const std::string& dirname,
   }
 
   std::vector<std::string> files;
-  if (dirname == CacheLocation::location().cache_log_directory()) {
+  if (dirname == Paths::Get().cache_log_directory()) {
     // Deletes the log files only.
     auto log_filter = [](const std::string& file_name) {
       return android::base::StartsWith(file_name, "last_log") ||
diff --git a/applypatch/imgpatch.cpp b/applypatch/imgpatch.cpp
index 2e4faaadf..b06a64f21 100644
--- a/applypatch/imgpatch.cpp
+++ b/applypatch/imgpatch.cpp
@@ -38,6 +38,7 @@
 #include <zlib.h>
 
 #include "edify/expr.h"
+#include "otautil/print_sha1.h"
 
 static inline int64_t Read8(const void *address) {
   return android::base::get_unaligned<int64_t>(address);
@@ -76,8 +77,10 @@ static bool ApplyBSDiffPatchAndStreamOutput(const uint8_t* src_data, size_t src_
   size_t actual_target_length = 0;
   size_t total_written = 0;
   static constexpr size_t buffer_size = 32768;
+  SHA_CTX sha_ctx;
+  SHA1_Init(&sha_ctx);
   auto compression_sink = [&strm, &actual_target_length, &expected_target_length, &total_written,
-                           &ret, &sink](const uint8_t* data, size_t len) -> size_t {
+                           &ret, &sink, &sha_ctx](const uint8_t* data, size_t len) -> size_t {
     // The input patch length for an update never exceeds INT_MAX.
     strm.avail_in = len;
     strm.next_in = data;
@@ -98,6 +101,20 @@ static bool ApplyBSDiffPatchAndStreamOutput(const uint8_t* src_data, size_t src_
 
       size_t have = buffer_size - strm.avail_out;
       total_written += have;
+
+      // TODO(b/67849209) Remove after debugging the unit test flakiness.
+      if (android::base::GetMinimumLogSeverity() <= android::base::LogSeverity::DEBUG &&
+          have != 0) {
+        SHA1_Update(&sha_ctx, data, len - strm.avail_in);
+        SHA_CTX temp_ctx;
+        memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
+        uint8_t digest_so_far[SHA_DIGEST_LENGTH];
+        SHA1_Final(digest_so_far, &temp_ctx);
+        LOG(DEBUG) << "Processed " << actual_target_length + len - strm.avail_in
+                   << " bytes input data in the sink function, sha1 so far: "
+                   << short_sha1(digest_so_far);
+      }
+
       if (sink(buffer.data(), have) != have) {
         LOG(ERROR) << "Failed to write " << have << " compressed bytes to output.";
         return 0;
@@ -111,6 +128,11 @@ static bool ApplyBSDiffPatchAndStreamOutput(const uint8_t* src_data, size_t src_
   int bspatch_result = ApplyBSDiffPatch(src_data, src_len, patch, patch_offset, compression_sink);
   deflateEnd(&strm);
 
+  if (android::base::GetMinimumLogSeverity() <= android::base::LogSeverity::DEBUG) {
+    uint8_t digest[SHA_DIGEST_LENGTH];
+    SHA1_Final(digest, &sha_ctx);
+    LOG(DEBUG) << "sha1 of " << actual_target_length << " bytes input data: " << short_sha1(digest);
+  }
   if (bspatch_result != 0) {
     return false;
   }
@@ -182,6 +204,8 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value&
         printf("Failed to apply bsdiff patch.\n");
         return -1;
       }
+
+      LOG(DEBUG) << "Processed chunk type normal";
     } else if (type == CHUNK_RAW) {
       const char* raw_header = patch_header + pos;
       pos += 4;
@@ -201,6 +225,8 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value&
         return -1;
       }
       pos += data_len;
+
+      LOG(DEBUG) << "Processed chunk type raw";
     } else if (type == CHUNK_DEFLATE) {
       // deflate chunks have an additional 60 bytes in their chunk header.
       const char* deflate_header = patch_header + pos;
@@ -276,6 +302,7 @@ int ApplyImagePatch(const unsigned char* old_data, size_t old_size, const Value&
         return -1;
       }
 
+      LOG(DEBUG) << "Processed chunk type deflate";
     } else {
       printf("patch chunk %d is unknown type %d\n", i, type);
       return -1;
diff --git a/common.h b/common.h
index 8b336f806..4228e71de 100644
--- a/common.h
+++ b/common.h
@@ -17,8 +17,8 @@
 #ifndef RECOVERY_COMMON_H
 #define RECOVERY_COMMON_H
 
-#include <stdio.h>
 #include <stdarg.h>
+#include <stdio.h>
 
 #include <string>
 
@@ -38,9 +38,9 @@ extern std::string stage;
 extern const char* reason;
 
 // fopen a file, mounting volumes and making parent dirs as necessary.
-FILE* fopen_path(const char *path, const char *mode);
+FILE* fopen_path(const std::string& path, const char* mode);
 
-void ui_print(const char* format, ...);
+void ui_print(const char* format, ...) __printflike(1, 2);
 
 bool is_ro_debuggable();
 
diff --git a/install.cpp b/install.cpp
index d05893171..30fd2c6be 100644
--- a/install.cpp
+++ b/install.cpp
@@ -52,6 +52,7 @@
 #include "otautil/SysUtil.h"
 #include "otautil/ThermalUtil.h"
 #include "otautil/error_code.h"
+#include "otautil/paths.h"
 #include "private/install.h"
 #include "roots.h"
 #include "ui.h"
@@ -627,10 +628,8 @@ static int really_install_package(const std::string& path, bool* wipe_cache, boo
   return result;
 }
 
-int install_package(const std::string& path, bool* wipe_cache, const std::string& install_file,
-                    bool needs_mount, int retry_count) {
+int install_package(const std::string& path, bool* wipe_cache, bool needs_mount, int retry_count) {
   CHECK(!path.empty());
-  CHECK(!install_file.empty());
   CHECK(wipe_cache != nullptr);
 
   modified_flash = true;
@@ -693,6 +692,7 @@ int install_package(const std::string& path, bool* wipe_cache, const std::string
 
   std::string log_content =
       android::base::Join(log_header, "\n") + "\n" + android::base::Join(log_buffer, "\n") + "\n";
+  const std::string& install_file = Paths::Get().temporary_install_file();
   if (!android::base::WriteStringToFile(log_content, install_file)) {
     PLOG(ERROR) << "failed to write " << install_file;
   }
diff --git a/install.h b/install.h
index f3fda3051..0f6670a35 100644
--- a/install.h
+++ b/install.h
@@ -17,7 +17,10 @@
 #ifndef RECOVERY_INSTALL_H_
 #define RECOVERY_INSTALL_H_
 
+#include <stddef.h>
+
 #include <string>
+
 #include <ziparchive/zip_archive.h>
 
 enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE, INSTALL_SKIPPED,
@@ -25,8 +28,8 @@ enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE, INSTALL_SK
 
 // Installs the given update package. If INSTALL_SUCCESS is returned and *wipe_cache is true on
 // exit, caller should wipe the cache partition.
-int install_package(const std::string& package, bool* wipe_cache, const std::string& install_file,
-                    bool needs_mount, int retry_count);
+int install_package(const std::string& package, bool* wipe_cache, bool needs_mount,
+                    int retry_count);
 
 // Verify the package by ota keys. Return true if the package is verified successfully,
 // otherwise return false.
diff --git a/otautil/Android.bp b/otautil/Android.bp
index 75cf69148..958f98b76 100644
--- a/otautil/Android.bp
+++ b/otautil/Android.bp
@@ -21,7 +21,7 @@ cc_library_static {
         "SysUtil.cpp",
         "DirUtil.cpp",
         "ThermalUtil.cpp",
-        "cache_location.cpp",
+        "paths.cpp",
         "rangeset.cpp",
     ],
 
diff --git a/otautil/include/otautil/cache_location.h b/otautil/include/otautil/cache_location.h
deleted file mode 100644
index 005395e5f..000000000
--- a/otautil/include/otautil/cache_location.h
+++ /dev/null
@@ -1,79 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
-#define _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
-
-#include <string>
-
-#include "android-base/macros.h"
-
-// A singleton class to maintain the update related locations. The locations should be only set
-// once at the start of the program.
-class CacheLocation {
- public:
-  static CacheLocation& location();
-
-  // getter and setter functions.
-  std::string cache_temp_source() const {
-    return cache_temp_source_;
-  }
-  void set_cache_temp_source(const std::string& temp_source) {
-    cache_temp_source_ = temp_source;
-  }
-
-  std::string last_command_file() const {
-    return last_command_file_;
-  }
-  void set_last_command_file(const std::string& last_command) {
-    last_command_file_ = last_command;
-  }
-
-  std::string stash_directory_base() const {
-    return stash_directory_base_;
-  }
-  void set_stash_directory_base(const std::string& base) {
-    stash_directory_base_ = base;
-  }
-
-  std::string cache_log_directory() const {
-    return cache_log_directory_;
-  }
-  void set_cache_log_directory(const std::string& log_dir) {
-    cache_log_directory_ = log_dir;
-  }
-
- private:
-  CacheLocation();
-  DISALLOW_COPY_AND_ASSIGN(CacheLocation);
-
-  // When there isn't enough room on the target filesystem to hold the patched version of the file,
-  // we copy the original here and delete it to free up space.  If the expected source file doesn't
-  // exist, or is corrupted, we look to see if the cached file contains the bits we want and use it
-  // as the source instead.  The default location for the cached source is "/cache/saved.file".
-  std::string cache_temp_source_;
-
-  // Location to save the last command that stashes blocks.
-  std::string last_command_file_;
-
-  // The base directory to write stashes during update.
-  std::string stash_directory_base_;
-
-  // The location of last_log & last_kmsg.
-  std::string cache_log_directory_;
-};
-
-#endif  // _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
diff --git a/otautil/include/otautil/paths.h b/otautil/include/otautil/paths.h
new file mode 100644
index 000000000..788c3de33
--- /dev/null
+++ b/otautil/include/otautil/paths.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _OTAUTIL_PATHS_H_
+#define _OTAUTIL_PATHS_H_
+
+#include <string>
+
+#include <android-base/macros.h>
+
+// A singleton class to maintain the update related paths. The paths should be only set once at the
+// start of the program.
+class Paths {
+ public:
+  static Paths& Get();
+
+  std::string cache_log_directory() const {
+    return cache_log_directory_;
+  }
+  void set_cache_log_directory(const std::string& log_dir) {
+    cache_log_directory_ = log_dir;
+  }
+
+  std::string cache_temp_source() const {
+    return cache_temp_source_;
+  }
+  void set_cache_temp_source(const std::string& temp_source) {
+    cache_temp_source_ = temp_source;
+  }
+
+  std::string last_command_file() const {
+    return last_command_file_;
+  }
+  void set_last_command_file(const std::string& last_command_file) {
+    last_command_file_ = last_command_file;
+  }
+
+  std::string stash_directory_base() const {
+    return stash_directory_base_;
+  }
+  void set_stash_directory_base(const std::string& base) {
+    stash_directory_base_ = base;
+  }
+
+  std::string temporary_install_file() const {
+    return temporary_install_file_;
+  }
+  void set_temporary_install_file(const std::string& install_file) {
+    temporary_install_file_ = install_file;
+  }
+
+  std::string temporary_log_file() const {
+    return temporary_log_file_;
+  }
+  void set_temporary_log_file(const std::string& log_file) {
+    temporary_log_file_ = log_file;
+  }
+
+ private:
+  Paths();
+  DISALLOW_COPY_AND_ASSIGN(Paths);
+
+  // Path to the directory that contains last_log and last_kmsg log files.
+  std::string cache_log_directory_;
+
+  // Path to the temporary source file on /cache. When there isn't enough room on the target
+  // filesystem to hold the patched version of the file, we copy the original here and delete it to
+  // free up space. If the expected source file doesn't exist, or is corrupted, we look to see if
+  // the cached file contains the bits we want and use it as the source instead.
+  std::string cache_temp_source_;
+
+  // Path to the last command file.
+  std::string last_command_file_;
+
+  // Path to the base directory to write stashes during update.
+  std::string stash_directory_base_;
+
+  // Path to the temporary file that contains the install result.
+  std::string temporary_install_file_;
+
+  // Path to the temporary log file while under recovery.
+  std::string temporary_log_file_;
+};
+
+#endif  // _OTAUTIL_PATHS_H_
diff --git a/otautil/cache_location.cpp b/otautil/paths.cpp
index 6139bf17b..ad9ec1145 100644
--- a/otautil/cache_location.cpp
+++ b/otautil/paths.cpp
@@ -14,20 +14,24 @@
  * limitations under the License.
  */
 
-#include "otautil/cache_location.h"
+#include "otautil/paths.h"
 
+constexpr const char kDefaultCacheLogDirectory[] = "/cache/recovery";
 constexpr const char kDefaultCacheTempSource[] = "/cache/saved.file";
 constexpr const char kDefaultLastCommandFile[] = "/cache/recovery/last_command";
 constexpr const char kDefaultStashDirectoryBase[] = "/cache/recovery";
-constexpr const char kDefaultCacheLogDirectory[] = "/cache/recovery";
+constexpr const char kDefaultTemporaryInstallFile[] = "/tmp/last_install";
+constexpr const char kDefaultTemporaryLogFile[] = "/tmp/recovery.log";
 
-CacheLocation& CacheLocation::location() {
-  static CacheLocation cache_location;
-  return cache_location;
+Paths& Paths::Get() {
+  static Paths paths;
+  return paths;
 }
 
-CacheLocation::CacheLocation()
-    : cache_temp_source_(kDefaultCacheTempSource),
+Paths::Paths()
+    : cache_log_directory_(kDefaultCacheLogDirectory),
+      cache_temp_source_(kDefaultCacheTempSource),
       last_command_file_(kDefaultLastCommandFile),
       stash_directory_base_(kDefaultStashDirectoryBase),
-      cache_log_directory_(kDefaultCacheLogDirectory) {}
+      temporary_install_file_(kDefaultTemporaryInstallFile),
+      temporary_log_file_(kDefaultTemporaryLogFile) {}
diff --git a/recovery.cpp b/recovery.cpp
index e266d9312..5a78faeac 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -68,6 +68,7 @@
 #include "minui/minui.h"
 #include "otautil/DirUtil.h"
 #include "otautil/error_code.h"
+#include "otautil/paths.h"
 #include "roots.h"
 #include "rotate_logs.h"
 #include "screen_ui.h"
@@ -108,20 +109,13 @@ static const char *CONVERT_FBE_DIR = "/tmp/convert_fbe";
 static const char *CONVERT_FBE_FILE = "/tmp/convert_fbe/convert_fbe";
 static const char *CACHE_ROOT = "/cache";
 static const char *DATA_ROOT = "/data";
+static const char* METADATA_ROOT = "/metadata";
 static const char *SDCARD_ROOT = "/sdcard";
-static const char *TEMPORARY_LOG_FILE = "/tmp/recovery.log";
-static const char *TEMPORARY_INSTALL_FILE = "/tmp/last_install";
 static const char *LAST_KMSG_FILE = "/cache/recovery/last_kmsg";
 static const char *LAST_LOG_FILE = "/cache/recovery/last_log";
 // We will try to apply the update package 5 times at most in case of an I/O error or
 // bspatch | imgpatch error.
 static const int RETRY_LIMIT = 4;
-static const int BATTERY_READ_TIMEOUT_IN_SEC = 10;
-// GmsCore enters recovery mode to install package when having enough battery
-// percentage. Normally, the threshold is 40% without charger and 20% with charger.
-// So we should check battery with a slightly lower limitation.
-static const int BATTERY_OK_PERCENTAGE = 20;
-static const int BATTERY_WITH_CHARGER_OK_PERCENTAGE = 15;
 static constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
 static constexpr const char* DEFAULT_LOCALE = "en-US";
 
@@ -184,8 +178,8 @@ struct selabel_handle* sehandle;
  */
 
 // Open a given path, mounting partitions as necessary.
-FILE* fopen_path(const char* path, const char* mode) {
-  if (ensure_path_mounted(path) != 0) {
+FILE* fopen_path(const std::string& path, const char* mode) {
+  if (ensure_path_mounted(path.c_str()) != 0) {
     LOG(ERROR) << "Can't mount " << path;
     return nullptr;
   }
@@ -195,19 +189,19 @@ FILE* fopen_path(const char* path, const char* mode) {
   if (strchr("wa", mode[0])) {
     mkdir_recursively(path, 0777, true, sehandle);
   }
-  return fopen(path, mode);
+  return fopen(path.c_str(), mode);
 }
 
 // close a file, log an error if the error indicator is set
-static void check_and_fclose(FILE *fp, const char *name) {
-    fflush(fp);
-    if (fsync(fileno(fp)) == -1) {
-        PLOG(ERROR) << "Failed to fsync " << name;
-    }
-    if (ferror(fp)) {
-        PLOG(ERROR) << "Error in " << name;
-    }
-    fclose(fp);
+static void check_and_fclose(FILE* fp, const std::string& name) {
+  fflush(fp);
+  if (fsync(fileno(fp)) == -1) {
+    PLOG(ERROR) << "Failed to fsync " << name;
+  }
+  if (ferror(fp)) {
+    PLOG(ERROR) << "Error in " << name;
+  }
+  fclose(fp);
 }
 
 bool is_ro_debuggable() {
@@ -407,27 +401,27 @@ static void save_kernel_log(const char* destination) {
     android::base::WriteStringToFile(buffer, destination);
 }
 
-// write content to the current pmsg session.
-static ssize_t __pmsg_write(const char *filename, const char *buf, size_t len) {
-    return __android_log_pmsg_file_write(LOG_ID_SYSTEM, ANDROID_LOG_INFO,
-                                         filename, buf, len);
+// Writes content to the current pmsg session.
+static ssize_t __pmsg_write(const std::string& filename, const std::string& buf) {
+  return __android_log_pmsg_file_write(LOG_ID_SYSTEM, ANDROID_LOG_INFO, filename.c_str(),
+                                       buf.data(), buf.size());
 }
 
-static void copy_log_file_to_pmsg(const char* source, const char* destination) {
-    std::string content;
-    android::base::ReadFileToString(source, &content);
-    __pmsg_write(destination, content.c_str(), content.length());
+static void copy_log_file_to_pmsg(const std::string& source, const std::string& destination) {
+  std::string content;
+  android::base::ReadFileToString(source, &content);
+  __pmsg_write(destination, content);
 }
 
 // How much of the temp log we have copied to the copy in cache.
 static off_t tmplog_offset = 0;
 
-static void copy_log_file(const char* source, const char* destination, bool append) {
+static void copy_log_file(const std::string& source, const std::string& destination, bool append) {
   FILE* dest_fp = fopen_path(destination, append ? "ae" : "we");
   if (dest_fp == nullptr) {
     PLOG(ERROR) << "Can't open " << destination;
   } else {
-    FILE* source_fp = fopen(source, "re");
+    FILE* source_fp = fopen(source.c_str(), "re");
     if (source_fp != nullptr) {
       if (append) {
         fseeko(source_fp, tmplog_offset, SEEK_SET);  // Since last write
@@ -447,39 +441,38 @@ static void copy_log_file(const char* source, const char* destination, bool appe
 }
 
 static void copy_logs() {
-    // We only rotate and record the log of the current session if there are
-    // actual attempts to modify the flash, such as wipes, installs from BCB
-    // or menu selections. This is to avoid unnecessary rotation (and
-    // possible deletion) of log files, if it does not do anything loggable.
-    if (!modified_flash) {
-        return;
-    }
+  // We only rotate and record the log of the current session if there are actual attempts to modify
+  // the flash, such as wipes, installs from BCB or menu selections. This is to avoid unnecessary
+  // rotation (and possible deletion) of log files, if it does not do anything loggable.
+  if (!modified_flash) {
+    return;
+  }
 
-    // Always write to pmsg, this allows the OTA logs to be caught in logcat -L
-    copy_log_file_to_pmsg(TEMPORARY_LOG_FILE, LAST_LOG_FILE);
-    copy_log_file_to_pmsg(TEMPORARY_INSTALL_FILE, LAST_INSTALL_FILE);
+  // Always write to pmsg, this allows the OTA logs to be caught in `logcat -L`.
+  copy_log_file_to_pmsg(Paths::Get().temporary_log_file(), LAST_LOG_FILE);
+  copy_log_file_to_pmsg(Paths::Get().temporary_install_file(), LAST_INSTALL_FILE);
 
-    // We can do nothing for now if there's no /cache partition.
-    if (!has_cache) {
-        return;
-    }
+  // We can do nothing for now if there's no /cache partition.
+  if (!has_cache) {
+    return;
+  }
 
-    ensure_path_mounted(LAST_LOG_FILE);
-    ensure_path_mounted(LAST_KMSG_FILE);
-    rotate_logs(LAST_LOG_FILE, LAST_KMSG_FILE);
-
-    // Copy logs to cache so the system can find out what happened.
-    copy_log_file(TEMPORARY_LOG_FILE, LOG_FILE, true);
-    copy_log_file(TEMPORARY_LOG_FILE, LAST_LOG_FILE, false);
-    copy_log_file(TEMPORARY_INSTALL_FILE, LAST_INSTALL_FILE, false);
-    save_kernel_log(LAST_KMSG_FILE);
-    chmod(LOG_FILE, 0600);
-    chown(LOG_FILE, AID_SYSTEM, AID_SYSTEM);
-    chmod(LAST_KMSG_FILE, 0600);
-    chown(LAST_KMSG_FILE, AID_SYSTEM, AID_SYSTEM);
-    chmod(LAST_LOG_FILE, 0640);
-    chmod(LAST_INSTALL_FILE, 0644);
-    sync();
+  ensure_path_mounted(LAST_LOG_FILE);
+  ensure_path_mounted(LAST_KMSG_FILE);
+  rotate_logs(LAST_LOG_FILE, LAST_KMSG_FILE);
+
+  // Copy logs to cache so the system can find out what happened.
+  copy_log_file(Paths::Get().temporary_log_file(), LOG_FILE, true);
+  copy_log_file(Paths::Get().temporary_log_file(), LAST_LOG_FILE, false);
+  copy_log_file(Paths::Get().temporary_install_file(), LAST_INSTALL_FILE, false);
+  save_kernel_log(LAST_KMSG_FILE);
+  chmod(LOG_FILE, 0600);
+  chown(LOG_FILE, AID_SYSTEM, AID_SYSTEM);
+  chmod(LAST_KMSG_FILE, 0600);
+  chown(LAST_KMSG_FILE, AID_SYSTEM, AID_SYSTEM);
+  chmod(LAST_LOG_FILE, 0640);
+  chmod(LAST_INSTALL_FILE, 0644);
+  sync();
 }
 
 // Clear the recovery command and prepare to boot a (hopefully working) system,
@@ -752,11 +745,19 @@ static bool wipe_data(Device* device) {
     modified_flash = true;
 
     ui->Print("\n-- Wiping data...\n");
-    bool success =
-        device->PreWipeData() &&
-        erase_volume("/data") &&
-        (has_cache ? erase_volume("/cache") : true) &&
-        device->PostWipeData();
+    bool success = device->PreWipeData();
+    if (success) {
+      success &= erase_volume(DATA_ROOT);
+      if (has_cache) {
+        success &= erase_volume(CACHE_ROOT);
+      }
+      if (volume_for_mount_point(METADATA_ROOT) != nullptr) {
+        success &= erase_volume(METADATA_ROOT);
+      }
+    }
+    if (success) {
+      success &= device->PostWipeData();
+    }
     ui->Print("Data wipe %s.\n", success ? "complete" : "failed");
     return success;
 }
@@ -957,10 +958,10 @@ static void choose_recovery_file(Device* device) {
     }
   } else {
     // If cache partition is not found, view /tmp/recovery.log instead.
-    if (access(TEMPORARY_LOG_FILE, R_OK) == -1) {
+    if (access(Paths::Get().temporary_log_file().c_str(), R_OK) == -1) {
       return;
     } else {
-      entries.push_back(TEMPORARY_LOG_FILE);
+      entries.push_back(Paths::Get().temporary_log_file());
     }
   }
 
@@ -1082,8 +1083,7 @@ static int apply_from_sdcard(Device* device, bool* wipe_cache) {
             }
         }
 
-        result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache,
-                                 TEMPORARY_INSTALL_FILE, false, 0/*retry_count*/);
+        result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, wipe_cache, false, 0 /*retry_count*/);
         break;
     }
 
@@ -1160,7 +1160,7 @@ static Device::BuiltinAction prompt_and_wait(Device* device, int status) {
         {
           bool adb = (chosen_action == Device::APPLY_ADB_SIDELOAD);
           if (adb) {
-            status = apply_from_adb(&should_wipe_cache, TEMPORARY_INSTALL_FILE);
+            status = apply_from_adb(&should_wipe_cache);
           } else {
             status = apply_from_sdcard(device, &should_wipe_cache);
           }
@@ -1259,7 +1259,7 @@ void UiLogger(android::base::LogId /* id */, android::base::LogSeverity severity
   }
 }
 
-static bool is_battery_ok() {
+static bool is_battery_ok(int* required_battery_level) {
   using android::hardware::health::V1_0::BatteryStatus;
   using android::hardware::health::V2_0::Result;
   using android::hardware::health::V2_0::toString;
@@ -1278,14 +1278,15 @@ static bool is_battery_ok() {
     .batteryChargeCounterPath = android::String8(android::String8::kEmptyString),
     .batteryFullChargePath = android::String8(android::String8::kEmptyString),
     .batteryCycleCountPath = android::String8(android::String8::kEmptyString),
-    .energyCounter = NULL,
+    .energyCounter = nullptr,
     .boot_min_cap = 0,
-    .screen_on = NULL
+    .screen_on = nullptr
   };
 
   auto health =
       android::hardware::health::V2_0::implementation::Health::initInstance(&healthd_config);
 
+  static constexpr int BATTERY_READ_TIMEOUT_IN_SEC = 10;
   int wait_second = 0;
   while (true) {
     auto charge_status = BatteryStatus::UNKNOWN;
@@ -1328,9 +1329,15 @@ static bool is_battery_ok() {
     if (res != Result::SUCCESS) {
       capacity = 100;
     }
-    return (charged && capacity >= BATTERY_WITH_CHARGER_OK_PERCENTAGE) ||
-           (!charged && capacity >= BATTERY_OK_PERCENTAGE);
-    }
+
+    // GmsCore enters recovery mode to install package when having enough battery percentage.
+    // Normally, the threshold is 40% without charger and 20% with charger. So we should check
+    // battery with a slightly lower limitation.
+    static constexpr int BATTERY_OK_PERCENTAGE = 20;
+    static constexpr int BATTERY_WITH_CHARGER_OK_PERCENTAGE = 15;
+    *required_battery_level = charged ? BATTERY_WITH_CHARGER_OK_PERCENTAGE : BATTERY_OK_PERCENTAGE;
+    return capacity >= *required_battery_level;
+  }
 }
 
 // Set the retry count to |retry_count| in BCB.
@@ -1362,19 +1369,20 @@ static bool bootreason_in_blacklist() {
   return false;
 }
 
-static void log_failure_code(ErrorCode code, const char *update_package) {
-    std::vector<std::string> log_buffer = {
-        update_package,
-        "0",  // install result
-        "error: " + std::to_string(code),
-    };
-    std::string log_content = android::base::Join(log_buffer, "\n");
-    if (!android::base::WriteStringToFile(log_content, TEMPORARY_INSTALL_FILE)) {
-        PLOG(ERROR) << "failed to write " << TEMPORARY_INSTALL_FILE;
-    }
+static void log_failure_code(ErrorCode code, const std::string& update_package) {
+  std::vector<std::string> log_buffer = {
+    update_package,
+    "0",  // install result
+    "error: " + std::to_string(code),
+  };
+  std::string log_content = android::base::Join(log_buffer, "\n");
+  const std::string& install_file = Paths::Get().temporary_install_file();
+  if (!android::base::WriteStringToFile(log_content, install_file)) {
+    PLOG(ERROR) << "Failed to write " << install_file;
+  }
 
-    // Also write the info into last_log.
-    LOG(INFO) << log_content;
+  // Also write the info into last_log.
+  LOG(INFO) << log_content;
 }
 
 int main(int argc, char **argv) {
@@ -1407,7 +1415,7 @@ int main(int argc, char **argv) {
 
   // redirect_stdio should be called only in non-sideload mode. Otherwise
   // we may have two logger instances with different timestamps.
-  redirect_stdio(TEMPORARY_LOG_FILE);
+  redirect_stdio(Paths::Get().temporary_log_file().c_str());
 
   printf("Starting recovery (pid %d) on %s", getpid(), ctime(&start));
 
@@ -1557,9 +1565,10 @@ int main(int argc, char **argv) {
     // to log the update attempt since update_package is non-NULL.
     modified_flash = true;
 
-    if (retry_count == 0 && !is_battery_ok()) {
-      ui->Print("battery capacity is not enough for installing package, needed is %d%%\n",
-                BATTERY_OK_PERCENTAGE);
+    int required_battery_level;
+    if (retry_count == 0 && !is_battery_ok(&required_battery_level)) {
+      ui->Print("battery capacity is not enough for installing package: %d%% needed\n",
+                required_battery_level);
       // Log the error code to last_install when installation skips due to
       // low battery.
       log_failure_code(kLowBattery, update_package);
@@ -1576,8 +1585,7 @@ int main(int argc, char **argv) {
         set_retry_bootloader_message(retry_count + 1, args);
       }
 
-      status = install_package(update_package, &should_wipe_cache, TEMPORARY_INSTALL_FILE, true,
-                               retry_count);
+      status = install_package(update_package, &should_wipe_cache, true, retry_count);
       if (status == INSTALL_SUCCESS && should_wipe_cache) {
         wipe_cache(false, device);
       }
@@ -1638,7 +1646,7 @@ int main(int argc, char **argv) {
     if (!sideload_auto_reboot) {
       ui->ShowText(true);
     }
-    status = apply_from_adb(&should_wipe_cache, TEMPORARY_INSTALL_FILE);
+    status = apply_from_adb(&should_wipe_cache);
     if (status == INSTALL_SUCCESS && should_wipe_cache) {
       if (!wipe_cache(false, device)) {
         status = INSTALL_ERROR;
diff --git a/sample_updater/README.md b/sample_updater/README.md
deleted file mode 100644
index a06c52d4b..000000000
--- a/sample_updater/README.md
+++ /dev/null
@@ -1 +0,0 @@
-# System update sample app.
diff --git a/sample_updater/res/layout/activity_main.xml b/sample_updater/res/layout/activity_main.xml
deleted file mode 100644
index bd7d68677..000000000
--- a/sample_updater/res/layout/activity_main.xml
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--
-  Copyright (C) 2018 The Android Open Source Project
-  Licensed under the Apache License, Version 2.0 (the "License");
-  you may not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-      http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-  -->
-
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
-    android:layout_height="match_parent">
-
-</LinearLayout>
diff --git a/sample_updater/src/com/android/update/ui/SystemUpdateActivity.java b/sample_updater/src/com/android/update/ui/SystemUpdateActivity.java
deleted file mode 100644
index e57b1673c..000000000
--- a/sample_updater/src/com/android/update/ui/SystemUpdateActivity.java
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.update.ui;
-
-import android.app.Activity;
-import android.os.UpdateEngine;
-import android.os.UpdateEngineCallback;
-
-/** Main update activity. */
-public class SystemUpdateActivity extends Activity {
-
-  private UpdateEngine updateEngine;
-  private UpdateEngineCallbackImpl updateEngineCallbackImpl = new UpdateEngineCallbackImpl(this);
-
-  @Override
-  public void onResume() {
-    super.onResume();
-    updateEngine = new UpdateEngine();
-    updateEngine.bind(updateEngineCallbackImpl);
-  }
-
-  @Override
-  public void onPause() {
-    updateEngine.unbind();
-    super.onPause();
-  }
-
-  void onStatusUpdate(int i, float v) {
-    // Handle update engine status update
-  }
-
-  void onPayloadApplicationComplete(int i) {
-    // Handle apply payload completion
-  }
-
-  private static class UpdateEngineCallbackImpl extends UpdateEngineCallback {
-
-    private final SystemUpdateActivity activity;
-
-    public UpdateEngineCallbackImpl(SystemUpdateActivity activity) {
-      this.activity = activity;
-    }
-
-    @Override
-    public void onStatusUpdate(int i, float v) {
-      activity.onStatusUpdate(i, v);
-    }
-
-    @Override
-    public void onPayloadApplicationComplete(int i) {
-      activity.onPayloadApplicationComplete(i);
-    }
-  }
-}
diff --git a/tests/component/applypatch_test.cpp b/tests/component/applypatch_test.cpp
index f19f28c60..4e4430919 100644
--- a/tests/component/applypatch_test.cpp
+++ b/tests/component/applypatch_test.cpp
@@ -16,7 +16,6 @@
 
 #include <dirent.h>
 #include <fcntl.h>
-#include <gtest/gtest.h>
 #include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -31,22 +30,66 @@
 #include <vector>
 
 #include <android-base/file.h>
+#include <android-base/logging.h>
 #include <android-base/stringprintf.h>
 #include <android-base/test_utils.h>
 #include <android-base/unique_fd.h>
 #include <bsdiff/bsdiff.h>
+#include <gtest/gtest.h>
 #include <openssl/sha.h>
+#include <zlib.h>
 
 #include "applypatch/applypatch.h"
 #include "applypatch/applypatch_modes.h"
 #include "common/test_constants.h"
-#include "otautil/cache_location.h"
+#include "otautil/paths.h"
 #include "otautil/print_sha1.h"
 
 using namespace std::string_literals;
 
+// TODO(b/67849209) Remove after debug the flakiness.
+static void DecompressAndDumpRecoveryImage(const std::string& image_path) {
+  // Expected recovery_image structure
+  // chunk normal:  45066 bytes
+  // chunk deflate: 479442 bytes
+  // chunk normal:  5199 bytes
+  std::string recovery_content;
+  ASSERT_TRUE(android::base::ReadFileToString(image_path, &recovery_content));
+  ASSERT_GT(recovery_content.size(), 45066 + 5199);
+
+  z_stream strm = {};
+  strm.avail_in = recovery_content.size() - 45066 - 5199;
+  strm.next_in =
+      const_cast<uint8_t*>(reinterpret_cast<const uint8_t*>(recovery_content.data())) + 45066;
+
+  ASSERT_EQ(Z_OK, inflateInit2(&strm, -15));
+
+  constexpr unsigned int BUFFER_SIZE = 32768;
+  std::vector<uint8_t> uncompressed_data(BUFFER_SIZE);
+  size_t uncompressed_length = 0;
+  SHA_CTX ctx;
+  SHA1_Init(&ctx);
+  int ret;
+  do {
+    strm.avail_out = BUFFER_SIZE;
+    strm.next_out = uncompressed_data.data();
+
+    ret = inflate(&strm, Z_NO_FLUSH);
+    ASSERT_GE(ret, 0);
+
+    SHA1_Update(&ctx, uncompressed_data.data(), BUFFER_SIZE - strm.avail_out);
+    uncompressed_length += BUFFER_SIZE - strm.avail_out;
+  } while (ret != Z_STREAM_END);
+  inflateEnd(&strm);
+
+  uint8_t digest[SHA_DIGEST_LENGTH];
+  SHA1_Final(digest, &ctx);
+  GTEST_LOG_(INFO) << "uncompressed length " << uncompressed_length
+                   << " sha1: " << short_sha1(digest);
+}
+
 static void sha1sum(const std::string& fname, std::string* sha1, size_t* fsize = nullptr) {
-  ASSERT_NE(nullptr, sha1);
+  ASSERT_TRUE(sha1 != nullptr);
 
   std::string data;
   ASSERT_TRUE(android::base::ReadFileToString(fname, &data));
@@ -68,6 +111,14 @@ static void mangle_file(const std::string& fname) {
   ASSERT_TRUE(android::base::WriteStringToFile(content, fname));
 }
 
+static void test_logger(android::base::LogId /* id */, android::base::LogSeverity severity,
+                        const char* /* tag */, const char* /* file */, unsigned int /* line */,
+                        const char* message) {
+  if (severity >= android::base::GetMinimumLogSeverity()) {
+    fprintf(stdout, "%s\n", message);
+  }
+}
+
 class ApplyPatchTest : public ::testing::Test {
  public:
   virtual void SetUp() override {
@@ -101,14 +152,16 @@ class ApplyPatchCacheTest : public ApplyPatchTest {
  protected:
   void SetUp() override {
     ApplyPatchTest::SetUp();
-    CacheLocation::location().set_cache_temp_source(old_file);
+    Paths::Get().set_cache_temp_source(old_file);
   }
 };
 
 class ApplyPatchModesTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    CacheLocation::location().set_cache_temp_source(cache_source.path);
+    Paths::Get().set_cache_temp_source(cache_source.path);
+    android::base::InitLogging(nullptr, &test_logger);
+    android::base::SetMinimumLogSeverity(android::base::LogSeverity::DEBUG);
   }
 
   TemporaryFile cache_source;
@@ -146,7 +199,7 @@ class FreeCacheTest : public ::testing::Test {
   }
 
   void SetUp() override {
-    CacheLocation::location().set_cache_log_directory(mock_log_dir.path);
+    Paths::Get().set_cache_log_directory(mock_log_dir.path);
   }
 
   // A mock method to calculate the free space. It assumes the partition has a total size of 40960
@@ -306,7 +359,11 @@ TEST_F(ApplyPatchModesTest, PatchModeEmmcTargetWithoutBonusFile) {
                                     recovery_img_sha1.c_str(),
                                     recovery_img_size_arg.c_str(),
                                     patch_arg.c_str() };
-  ASSERT_EQ(0, applypatch_modes(args.size(), args.data()));
+
+  if (applypatch_modes(args.size(), args.data()) != 0) {
+    DecompressAndDumpRecoveryImage(tgt_file.path);
+    FAIL();
+  }
 }
 
 TEST_F(ApplyPatchModesTest, PatchModeEmmcTargetWithMultiplePatches) {
@@ -349,7 +406,11 @@ TEST_F(ApplyPatchModesTest, PatchModeEmmcTargetWithMultiplePatches) {
   for (const auto& arg : args) {
     printf("  %s\n", arg);
   }
-  ASSERT_EQ(0, applypatch_modes(args.size(), args.data()));
+
+  if (applypatch_modes(args.size(), args.data()) != 0) {
+    DecompressAndDumpRecoveryImage(tgt_file.path);
+    FAIL();
+  }
 }
 
 // Ensures that applypatch works with a bsdiff based recovery-from-boot.p.
diff --git a/tests/component/updater_test.cpp b/tests/component/updater_test.cpp
index 5bfd7cb40..5d3b2d996 100644
--- a/tests/component/updater_test.cpp
+++ b/tests/component/updater_test.cpp
@@ -41,8 +41,8 @@
 #include "common/test_constants.h"
 #include "edify/expr.h"
 #include "otautil/SysUtil.h"
-#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
+#include "otautil/paths.h"
 #include "otautil/print_sha1.h"
 #include "updater/blockimg.h"
 #include "updater/install.h"
@@ -106,10 +106,9 @@ class UpdaterTest : public ::testing::Test {
     RegisterInstallFunctions();
     RegisterBlockImageFunctions();
 
-    // Mock the location of last_command_file.
-    CacheLocation::location().set_cache_temp_source(temp_saved_source_.path);
-    CacheLocation::location().set_last_command_file(temp_last_command_.path);
-    CacheLocation::location().set_stash_directory_base(temp_stash_base_.path);
+    Paths::Get().set_cache_temp_source(temp_saved_source_.path);
+    Paths::Get().set_last_command_file(temp_last_command_.path);
+    Paths::Get().set_stash_directory_base(temp_stash_base_.path);
   }
 
   TemporaryFile temp_saved_source_;
@@ -719,7 +718,7 @@ TEST_F(UpdaterTest, brotli_new_data) {
 }
 
 TEST_F(UpdaterTest, last_command_update) {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  std::string last_command_file = Paths::Get().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');
@@ -806,7 +805,7 @@ TEST_F(UpdaterTest, last_command_update) {
 }
 
 TEST_F(UpdaterTest, last_command_update_unresumable) {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  std::string last_command_file = Paths::Get().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');
@@ -861,7 +860,7 @@ TEST_F(UpdaterTest, last_command_update_unresumable) {
 }
 
 TEST_F(UpdaterTest, last_command_verify) {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  std::string last_command_file = Paths::Get().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');
diff --git a/updater/blockimg.cpp b/updater/blockimg.cpp
index e72ddd313..d767d4467 100644
--- a/updater/blockimg.cpp
+++ b/updater/blockimg.cpp
@@ -15,8 +15,8 @@
  */
 
 #include <ctype.h>
-#include <errno.h>
 #include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <linux/fs.h>
@@ -25,13 +25,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <sys/ioctl.h>
 #include <time.h>
 #include <unistd.h>
-#include <fec/io.h>
 
 #include <functional>
 #include <limits>
@@ -47,14 +46,15 @@
 #include <android-base/unique_fd.h>
 #include <applypatch/applypatch.h>
 #include <brotli/decode.h>
+#include <fec/io.h>
 #include <openssl/sha.h>
 #include <private/android_filesystem_config.h>
 #include <ziparchive/zip_archive.h>
 
 #include "edify/expr.h"
 #include "otafault/ota_io.h"
-#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
+#include "otautil/paths.h"
 #include "otautil/print_sha1.h"
 #include "otautil/rangeset.h"
 #include "updater/install.h"
@@ -74,7 +74,7 @@ static bool is_retry = false;
 static std::unordered_map<std::string, RangeSet> stash_map;
 
 static void DeleteLastCommandFile() {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  const std::string& last_command_file = Paths::Get().last_command_file();
   if (unlink(last_command_file.c_str()) == -1 && errno != ENOENT) {
     PLOG(ERROR) << "Failed to unlink: " << last_command_file;
   }
@@ -83,7 +83,7 @@ static void DeleteLastCommandFile() {
 // Parse the last command index of the last update and save the result to |last_command_index|.
 // Return true if we successfully read the index.
 static bool ParseLastCommandFile(int* last_command_index) {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  const std::string& last_command_file = Paths::Get().last_command_file();
   android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(last_command_file.c_str(), O_RDONLY)));
   if (fd == -1) {
     if (errno != ENOENT) {
@@ -119,7 +119,7 @@ static bool ParseLastCommandFile(int* last_command_index) {
 // Update the last command index in the last_command_file if the current command writes to the
 // stash either explicitly or implicitly.
 static bool UpdateLastCommandIndex(int command_index, const std::string& command_string) {
-  std::string last_command_file = CacheLocation::location().last_command_file();
+  const std::string& last_command_file = Paths::Get().last_command_file();
   std::string last_command_tmp = last_command_file + ".tmp";
   std::string content = std::to_string(command_index) + "\n" + command_string;
   android::base::unique_fd wfd(
@@ -672,15 +672,11 @@ static int VerifyBlocks(const std::string& expected, const std::vector<uint8_t>&
 }
 
 static std::string GetStashFileName(const std::string& base, const std::string& id,
-        const std::string& postfix) {
-    if (base.empty()) {
-        return "";
-    }
-
-    std::string fn(CacheLocation::location().stash_directory_base());
-    fn += "/" + base + "/" + id + postfix;
-
-    return fn;
+                                    const std::string& postfix) {
+  if (base.empty()) {
+    return "";
+  }
+  return Paths::Get().stash_directory_base() + "/" + base + "/" + id + postfix;
 }
 
 // Does a best effort enumeration of stash files. Ignores possible non-file items in the stash
@@ -1697,7 +1693,7 @@ static Value* PerformBlockImageUpdate(const char* name, State* state,
   for (size_t i = 0; i < cmdcount; ++i) {
     if (cmd_map.find(commands[i].name) != cmd_map.end()) {
       LOG(ERROR) << "Error: command [" << commands[i].name << "] already exists in the cmd map.";
-      return StringValue(strdup(""));
+      return StringValue("");
     }
     cmd_map[commands[i].name] = &commands[i];
   }
diff --git a/updater/updater.cpp b/updater/updater.cpp
index 1d6b172bb..bf7c36caf 100644
--- a/updater/updater.cpp
+++ b/updater/updater.cpp
@@ -17,9 +17,9 @@
 #include "updater/updater.h"
 
 #include <stdio.h>
-#include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #include <string>
 
@@ -34,7 +34,6 @@
 #include "otafault/config.h"
 #include "otautil/DirUtil.h"
 #include "otautil/SysUtil.h"
-#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
 #include "updater/blockimg.h"
 #include "updater/install.h"
diff --git a/updater_sample/.gitignore b/updater_sample/.gitignore
new file mode 100644
index 000000000..f84647245
--- /dev/null
+++ b/updater_sample/.gitignore
@@ -0,0 +1,10 @@
+*~
+*.bak
+*.pyc
+*.pyc-2.4
+Thumbs.db
+*.iml
+.idea/
+gen/
+.vscode
+local.properties
diff --git a/sample_updater/Android.mk b/updater_sample/Android.mk
index 2b0fcbeec..2786de44f 100644
--- a/sample_updater/Android.mk
+++ b/updater_sample/Android.mk
@@ -15,13 +15,18 @@
 #
 
 LOCAL_PATH := $(call my-dir)
-
 include $(CLEAR_VARS)
 
-LOCAL_PACKAGE_NAME := SystemUpdateApp
+LOCAL_PACKAGE_NAME := SystemUpdaterSample
 LOCAL_SDK_VERSION := system_current
-LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE_TAGS := samples
+
+# TODO: enable proguard and use proguard.flags file
+LOCAL_PROGUARD_ENABLED := disabled
 
 LOCAL_SRC_FILES := $(call all-java-files-under, src)
 
 include $(BUILD_PACKAGE)
+
+# Use the following include to make our test apk.
+include $(call all-makefiles-under,$(LOCAL_PATH))
diff --git a/sample_updater/AndroidManifest.xml b/updater_sample/AndroidManifest.xml
index 66414b5d3..5bbb21c84 100644
--- a/sample_updater/AndroidManifest.xml
+++ b/updater_sample/AndroidManifest.xml
@@ -15,17 +15,22 @@
   -->
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-          package="com.android.update">
+          package="com.example.android.systemupdatersample">
 
-  <application android:label="Sample Updater">
-    <activity android:name=".ui.SystemUpdateActivity"
-              android:label="Sample Updater">
-      <intent-filter>
-        <action android:name="android.intent.action.MAIN" />
-        <category android:name="android.intent.category.LAUNCHER" />
-      </intent-filter>
-    </activity>
-  </application>
+    <uses-sdk android:minSdkVersion="27" android:targetSdkVersion="27" />
 
-</manifest>
+    <application
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round">
+        <activity
+            android:name=".ui.MainActivity"
+            android:label="@string/app_name" >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
 
+</manifest>
diff --git a/updater_sample/README.md b/updater_sample/README.md
new file mode 100644
index 000000000..ee1faaf85
--- /dev/null
+++ b/updater_sample/README.md
@@ -0,0 +1,98 @@
+# SystemUpdaterSample
+
+This app demonstrates how to use Android system updates APIs to install
+[OTA updates](https://source.android.com/devices/tech/ota/). It contains a sample
+client for `update_engine` to install A/B (seamless) updates and a sample of
+applying non-A/B updates using `recovery`.
+
+A/B (seamless) update is available since Android Nougat (API 24), but this sample
+targets the latest android.
+
+
+## Workflow
+
+SystemUpdaterSample app shows list of available updates on the UI. User is allowed
+to select an update and apply it to the device. App shows installation progress,
+logs can be found in `adb logcat`. User can stop or reset an update. Resetting
+the update requests update engine to cancel any ongoing update, and revert
+if the update has been applied. Stopping does not revert the applied update.
+
+
+## Update Config file
+
+In this sample updates are defined in JSON update config files.
+The structure of a config file is defined in
+`com.example.android.systemupdatersample.UpdateConfig`, example file is located
+at `res/raw/sample.json`.
+
+In real-life update system the config files expected to be served from a server
+to the app, but in this sample, the config files are stored on the device.
+The directory can be found in logs or on the UI. In most cases it should be located at
+`/data/user/0/com.example.android.systemupdatersample/files/configs/`.
+
+SystemUpdaterSample app downloads OTA package from `url`. If `ab_install_type`
+is `NON_STREAMING` then app downloads the whole package and
+passes it to the `update_engine`. If `ab_install_type` is `STREAMING`
+then app downloads only some files to prepare the streaming update and
+`update_engine` will stream only `payload.bin`.
+To support streaming A/B (seamless) update, OTA package file must be
+an uncompressed (ZIP_STORED) zip file.
+
+Config files can be generated using `tools/gen_update_config.py`.
+Running `./tools/gen_update_config.py --help` shows usage of the script.
+
+
+## Running on a device
+
+The commands expected to be run from `$ANDROID_BUILD_TOP`.
+
+1. Compile the app `$ mmma bootable/recovery/updater_sample`.
+2. Install the app to the device using `$ adb install <APK_PATH>`.
+3. Add update config files.
+
+
+## Development
+
+- [x] Create a UI with list of configs, current version,
+      control buttons, progress bar and log viewer
+- [x] Add `PayloadSpec` and `PayloadSpecs` for working with
+      update zip file
+- [x] Add `UpdateConfig` for working with json config files
+- [x] Add applying non-streaming update
+- [ ] Prepare streaming update (partially downloading package)
+- [ ] Add applying streaming update
+- [ ] Add tests for `MainActivity`
+- [ ] Add stop/reset the update
+- [ ] Verify system partition checksum for package
+- [ ] HAL compatibility check
+- [ ] Change partition demo
+- [ ] Add non-A/B updates demo
+
+
+## Running tests
+
+1. Build `$ mmma bootable/recovery/updater_sample/`
+2. Install app
+   `$ adb install $OUT/system/app/SystemUpdaterSample/SystemUpdaterSample.apk`
+3. Install tests
+   `$ adb install $OUT/testcases/SystemUpdaterSampleTests/SystemUpdaterSampleTests.apk`
+4. Run tests
+   `$ adb shell am instrument -w com.example.android.systemupdatersample.tests/android.support.test.runner.AndroidJUnitRunner`
+5. Run a test file
+   ```
+   $ adb shell am instrument \
+     -w com.example.android.systemupdatersample.tests/android.support.test.runner.AndroidJUnitRunner \
+     -c com.example.android.systemupdatersample.util.PayloadSpecsTest
+   ```
+
+
+## Getting access to `update_engine` API and read/write access to `/data`
+
+Run adb shell as a root, and set SELinux mode to permissive (0):
+
+```txt
+$ adb root
+$ adb shell
+# setenforce 0
+# getenforce
+```
diff --git a/updater_sample/res/layout/activity_main.xml b/updater_sample/res/layout/activity_main.xml
new file mode 100644
index 000000000..3cd772107
--- /dev/null
+++ b/updater_sample/res/layout/activity_main.xml
@@ -0,0 +1,163 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2018 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:padding="4dip"
+    android:gravity="center_horizontal"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent">
+
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_marginBottom="8dp"
+        android:layout_marginEnd="8dp"
+        android:layout_marginStart="8dp"
+        android:layout_marginTop="8dp"
+        >
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:orientation="vertical">
+
+            <TextView
+                android:id="@+id/textViewBuildtitle"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Current Build:" />
+
+            <TextView
+                android:id="@+id/textViewBuild"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/unknown" />
+
+            <Space
+                android:layout_width="match_parent"
+                android:layout_height="40dp" />
+
+            <TextView
+                android:id="@+id/textView4"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Apply an update" />
+
+            <TextView
+                android:id="@+id/textViewConfigsDirHint"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="4dp"
+                android:text="Config files located in NULL"
+                android:textColor="#777"
+                android:textSize="10sp"
+                android:textStyle="italic" />
+
+            <Spinner
+                android:id="@+id/spinnerConfigs"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp" />
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:orientation="horizontal">
+
+                <Button
+                    android:id="@+id/buttonReload"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:onClick="onReloadClick"
+                    android:text="Reload" />
+
+                <Button
+                    android:id="@+id/buttonViewConfig"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:onClick="onViewConfigClick"
+                    android:text="View config" />
+
+                <Button
+                    android:id="@+id/buttonApplyConfig"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:onClick="onApplyConfigClick"
+                    android:text="Apply" />
+            </LinearLayout>
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="24dp"
+                android:orientation="horizontal">
+
+                <TextView
+                    android:id="@+id/textView"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Running update status:" />
+
+                <TextView
+                    android:id="@+id/textViewStatus"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginLeft="8dp"
+                    android:text="@string/unknown" />
+            </LinearLayout>
+
+            <ProgressBar
+                android:id="@+id/progressBar"
+                style="?android:attr/progressBarStyleHorizontal"
+                android:layout_marginTop="8dp"
+                android:min="0"
+                android:max="100"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content" />
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="12dp"
+                android:orientation="horizontal">
+
+                <Button
+                    android:id="@+id/buttonStop"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:onClick="onStopClick"
+                    android:text="Stop" />
+
+                <Button
+                    android:id="@+id/buttonReset"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:onClick="onResetClick"
+                    android:text="Reset" />
+            </LinearLayout>
+
+        </LinearLayout>
+
+    </ScrollView>
+
+</LinearLayout>
diff --git a/updater_sample/res/mipmap-hdpi/ic_launcher.png b/updater_sample/res/mipmap-hdpi/ic_launcher.png
new file mode 100644
index 000000000..a2f590828
--- /dev/null
+++ b/updater_sample/res/mipmap-hdpi/ic_launcher.png
diff --git a/updater_sample/res/mipmap-hdpi/ic_launcher_round.png b/updater_sample/res/mipmap-hdpi/ic_launcher_round.png
new file mode 100644
index 000000000..1b5239980
--- /dev/null
+++ b/updater_sample/res/mipmap-hdpi/ic_launcher_round.png
diff --git a/updater_sample/res/raw/sample.json b/updater_sample/res/raw/sample.json
new file mode 100644
index 000000000..03335cc97
--- /dev/null
+++ b/updater_sample/res/raw/sample.json
@@ -0,0 +1,22 @@
+{
+    "__name": "name will be visible on UI",
+    "__url": "https:// or file:// uri to update file (zip, xz, ...)",
+    "__type": "NON_STREAMING (from local file) OR STREAMING (on the fly)",
+    "name": "SAMPLE-cake-release BUILD-12345",
+    "url": "file:///data/builds/android-update.zip",
+    "type": "NON_STREAMING",
+    "streaming_metadata": {
+        "__": "streaming_metadata is required only for streaming update",
+        "__property_files": "name, offset and size of files",
+        "property_files": [
+            {
+                "__filename": "payload.bin and payload_properties.txt are required",
+                "__offset": "defines beginning of update data in archive",
+                "__size": "size of the update data in archive",
+                "filename": "payload.bin",
+                "offset": 531,
+                "size": 5012323
+            }
+        ]
+    }
+}
diff --git a/updater_sample/res/values/strings.xml b/updater_sample/res/values/strings.xml
new file mode 100644
index 000000000..2b671ee5d
--- /dev/null
+++ b/updater_sample/res/values/strings.xml
@@ -0,0 +1,21 @@
+<!-- Copyright (C) 2018 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<resources>
+    <string name="app_name">SystemUpdaterSample</string>
+    <string name="action_reload">Reload</string>
+    <string name="unknown">Unknown</string>
+    <string name="close">CLOSE</string>
+</resources>
diff --git a/updater_sample/src/com/example/android/systemupdatersample/PayloadSpec.java b/updater_sample/src/com/example/android/systemupdatersample/PayloadSpec.java
new file mode 100644
index 000000000..90c5637ea
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/PayloadSpec.java
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample;
+
+import android.os.UpdateEngine;
+
+import java.util.List;
+
+/**
+ * Payload that will be given to {@link UpdateEngine#applyPayload)}.
+ */
+public class PayloadSpec {
+
+    /**
+     * Creates a payload spec {@link Builder}
+     */
+    public static Builder newBuilder() {
+        return new Builder();
+    }
+
+    private String mUrl;
+    private long mOffset;
+    private long mSize;
+    private List<String> mProperties;
+
+    public PayloadSpec(Builder b) {
+        this.mUrl = b.mUrl;
+        this.mOffset = b.mOffset;
+        this.mSize = b.mSize;
+        this.mProperties = b.mProperties;
+    }
+
+    public String getUrl() {
+        return mUrl;
+    }
+
+    public long getOffset() {
+        return mOffset;
+    }
+
+    public long getSize() {
+        return mSize;
+    }
+
+    public List<String> getProperties() {
+        return mProperties;
+    }
+
+    /**
+     * payload spec builder.
+     *
+     * <p>Usage:</p>
+     *
+     * {@code
+     *   PayloadSpec spec = PayloadSpec.newBuilder()
+     *     .url("url")
+     *     .build();
+     * }
+     */
+    public static class Builder {
+        private String mUrl;
+        private long mOffset;
+        private long mSize;
+        private List<String> mProperties;
+
+        public Builder() {
+        }
+
+        /**
+         * set url
+         */
+        public Builder url(String url) {
+            this.mUrl = url;
+            return this;
+        }
+
+        /**
+         * set offset
+         */
+        public Builder offset(long offset) {
+            this.mOffset = offset;
+            return this;
+        }
+
+        /**
+         * set size
+         */
+        public Builder size(long size) {
+            this.mSize = size;
+            return this;
+        }
+
+        /**
+         * set properties
+         */
+        public Builder properties(List<String> properties) {
+            this.mProperties = properties;
+            return this;
+        }
+
+        /**
+         * build {@link PayloadSpec}
+         */
+        public PayloadSpec build() {
+            return new PayloadSpec(this);
+        }
+    }
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java b/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java
new file mode 100644
index 000000000..cbee18fcb
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.io.File;
+import java.io.Serializable;
+
+/**
+ * UpdateConfig describes an update. It will be parsed from JSON, which is intended to
+ * be sent from server to the update app, but in this sample app it will be stored on the device.
+ */
+public class UpdateConfig implements Parcelable {
+
+    public static final int TYPE_NON_STREAMING = 0;
+    public static final int TYPE_STREAMING     = 1;
+
+    public static final Parcelable.Creator<UpdateConfig> CREATOR =
+            new Parcelable.Creator<UpdateConfig>() {
+                @Override
+                public UpdateConfig createFromParcel(Parcel source) {
+                    return new UpdateConfig(source);
+                }
+
+                @Override
+                public UpdateConfig[] newArray(int size) {
+                    return new UpdateConfig[size];
+                }
+            };
+
+    /** parse update config from json */
+    public static UpdateConfig fromJson(String json) throws JSONException {
+        UpdateConfig c = new UpdateConfig();
+
+        JSONObject o = new JSONObject(json);
+        c.mName = o.getString("name");
+        c.mUrl = o.getString("url");
+        if (TYPE_NON_STREAMING_JSON.equals(o.getString("type"))) {
+            c.mInstallType = TYPE_NON_STREAMING;
+        } else if (TYPE_STREAMING_JSON.equals(o.getString("type"))) {
+            c.mInstallType = TYPE_STREAMING;
+        } else {
+            throw new JSONException("Invalid type, expected either "
+                    + "NON_STREAMING or STREAMING, got " + o.getString("type"));
+        }
+        if (o.has("metadata")) {
+            c.mMetadata = new Metadata(
+                    o.getJSONObject("metadata").getInt("offset"),
+                    o.getJSONObject("metadata").getInt("size"));
+        }
+        c.mRawJson = json;
+        return c;
+    }
+
+    /**
+     * these strings are represent types in JSON config files
+     */
+    private static final String TYPE_NON_STREAMING_JSON  = "NON_STREAMING";
+    private static final String TYPE_STREAMING_JSON      = "STREAMING";
+
+    /** name will be visible on UI */
+    private String mName;
+
+    /** update zip file URI, can be https:// or file:// */
+    private String mUrl;
+
+    /** non-streaming (first saves locally) OR streaming (on the fly) */
+    private int mInstallType;
+
+    /** metadata is required only for streaming update */
+    private Metadata mMetadata;
+
+    private String mRawJson;
+
+    protected UpdateConfig() {
+    }
+
+    protected UpdateConfig(Parcel in) {
+        this.mName = in.readString();
+        this.mUrl = in.readString();
+        this.mInstallType = in.readInt();
+        this.mMetadata = (Metadata) in.readSerializable();
+        this.mRawJson = in.readString();
+    }
+
+    public UpdateConfig(String name, String url, int installType) {
+        this.mName = name;
+        this.mUrl = url;
+        this.mInstallType = installType;
+    }
+
+    public String getName() {
+        return mName;
+    }
+
+    public String getUrl() {
+        return mUrl;
+    }
+
+    public String getRawJson() {
+        return mRawJson;
+    }
+
+    public int getInstallType() {
+        return mInstallType;
+    }
+
+    /**
+     * "url" must be the file located on the device.
+     *
+     * @return File object for given url
+     */
+    public File getUpdatePackageFile() {
+        if (mInstallType != TYPE_NON_STREAMING) {
+            throw new RuntimeException("Expected non-streaming install type");
+        }
+        if (!mUrl.startsWith("file://")) {
+            throw new RuntimeException("url is expected to start with file://");
+        }
+        return new File(mUrl.substring(7, mUrl.length()));
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeString(mName);
+        dest.writeString(mUrl);
+        dest.writeInt(mInstallType);
+        dest.writeSerializable(mMetadata);
+        dest.writeString(mRawJson);
+    }
+
+    /**
+     * Metadata for STREAMING update
+     */
+    public static class Metadata implements Serializable {
+
+        private static final long serialVersionUID = 31042L;
+
+        /** defines beginning of update data in archive */
+        private long mOffset;
+
+        /** size of the update data in archive */
+        private long mSize;
+
+        public Metadata(long offset, long size) {
+            this.mOffset = offset;
+            this.mSize = size;
+        }
+
+        public long getOffset() {
+            return mOffset;
+        }
+
+        public long getSize() {
+            return mSize;
+        }
+    }
+
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/ui/MainActivity.java b/updater_sample/src/com/example/android/systemupdatersample/ui/MainActivity.java
new file mode 100644
index 000000000..72e1b2469
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/ui/MainActivity.java
@@ -0,0 +1,314 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.ui;
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.UpdateEngine;
+import android.os.UpdateEngineCallback;
+import android.util.Log;
+import android.view.View;
+import android.widget.ArrayAdapter;
+import android.widget.Button;
+import android.widget.ProgressBar;
+import android.widget.Spinner;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import com.example.android.systemupdatersample.R;
+import com.example.android.systemupdatersample.UpdateConfig;
+import com.example.android.systemupdatersample.updates.AbNonStreamingUpdate;
+import com.example.android.systemupdatersample.util.UpdateConfigs;
+import com.example.android.systemupdatersample.util.UpdateEngineErrorCodes;
+import com.example.android.systemupdatersample.util.UpdateEngineStatuses;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * UI for SystemUpdaterSample app.
+ */
+public class MainActivity extends Activity {
+
+    private TextView mTextViewBuild;
+    private Spinner mSpinnerConfigs;
+    private TextView mTextViewConfigsDirHint;
+    private Button mButtonReload;
+    private Button mButtonApplyConfig;
+    private Button mButtonStop;
+    private Button mButtonReset;
+    private ProgressBar mProgressBar;
+    private TextView mTextViewStatus;
+
+    private List<UpdateConfig> mConfigs;
+    private AtomicInteger mUpdateEngineStatus =
+            new AtomicInteger(UpdateEngine.UpdateStatusConstants.IDLE);
+    private UpdateEngine mUpdateEngine = new UpdateEngine();
+
+    /**
+     * Listen to {@code update_engine} events.
+     */
+    private UpdateEngineCallbackImpl mUpdateEngineCallback = new UpdateEngineCallbackImpl();
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+
+        this.mTextViewBuild = findViewById(R.id.textViewBuild);
+        this.mSpinnerConfigs = findViewById(R.id.spinnerConfigs);
+        this.mTextViewConfigsDirHint = findViewById(R.id.textViewConfigsDirHint);
+        this.mButtonReload = findViewById(R.id.buttonReload);
+        this.mButtonApplyConfig = findViewById(R.id.buttonApplyConfig);
+        this.mButtonStop = findViewById(R.id.buttonStop);
+        this.mButtonReset = findViewById(R.id.buttonReset);
+        this.mProgressBar = findViewById(R.id.progressBar);
+        this.mTextViewStatus = findViewById(R.id.textViewStatus);
+
+        this.mUpdateEngine.bind(mUpdateEngineCallback);
+
+        this.mTextViewConfigsDirHint.setText(UpdateConfigs.getConfigsRoot(this));
+
+        uiReset();
+
+        loadUpdateConfigs();
+    }
+
+    @Override
+    protected void onDestroy() {
+        this.mUpdateEngine.unbind();
+        super.onDestroy();
+    }
+
+    /**
+     * reload button is clicked
+     */
+    public void onReloadClick(View view) {
+        loadUpdateConfigs();
+    }
+
+    /**
+     * view config button is clicked
+     */
+    public void onViewConfigClick(View view) {
+        UpdateConfig config = mConfigs.get(mSpinnerConfigs.getSelectedItemPosition());
+        new AlertDialog.Builder(this)
+                .setTitle(config.getName())
+                .setMessage(config.getRawJson())
+                .setPositiveButton(R.string.close, (dialog, id) -> dialog.dismiss())
+                .show();
+    }
+
+    /**
+     * apply config button is clicked
+     */
+    public void onApplyConfigClick(View view) {
+        new AlertDialog.Builder(this)
+                .setTitle("Apply Update")
+                .setMessage("Do you really want to apply this update?")
+                .setIcon(android.R.drawable.ic_dialog_alert)
+                .setPositiveButton(android.R.string.ok, (dialog, whichButton) -> {
+                    uiSetUpdating();
+                    applyUpdate(getSelectedConfig());
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
+
+    /**
+     * stop button clicked
+     */
+    public void onStopClick(View view) {
+        new AlertDialog.Builder(this)
+                .setTitle("Stop Update")
+                .setMessage("Do you really want to cancel running update?")
+                .setIcon(android.R.drawable.ic_dialog_alert)
+                .setPositiveButton(android.R.string.ok, (dialog, whichButton) -> {
+                    uiReset();
+                    stopRunningUpdate();
+                })
+                .setNegativeButton(android.R.string.cancel, null).show();
+    }
+
+    /**
+     * reset button clicked
+     */
+    public void onResetClick(View view) {
+        new AlertDialog.Builder(this)
+                .setTitle("Reset Update")
+                .setMessage("Do you really want to cancel running update"
+                        + " and restore old version?")
+                .setIcon(android.R.drawable.ic_dialog_alert)
+                .setPositiveButton(android.R.string.ok, (dialog, whichButton) -> {
+                    uiReset();
+                    resetUpdate();
+                })
+                .setNegativeButton(android.R.string.cancel, null).show();
+    }
+
+    /**
+     * Invoked when anything changes. The value of {@code status} will
+     * be one of the values from {@link UpdateEngine.UpdateStatusConstants},
+     * and {@code percent} will be from {@code 0.0} to {@code 1.0}.
+     */
+    private void onStatusUpdate(int status, float percent) {
+        mProgressBar.setProgress((int) (100 * percent));
+        if (mUpdateEngineStatus.get() != status) {
+            mUpdateEngineStatus.set(status);
+            runOnUiThread(() -> {
+                Log.e("UpdateEngine", "StatusUpdate - status="
+                        + UpdateEngineStatuses.getStatusText(status)
+                        + "/" + status);
+                setUiStatus(status);
+                Toast.makeText(this, "Update Status changed", Toast.LENGTH_LONG)
+                        .show();
+            });
+        }
+    }
+
+    /**
+     * Invoked when the payload has been applied, whether successfully or
+     * unsuccessfully. The value of {@code errorCode} will be one of the
+     * values from {@link UpdateEngine.ErrorCodeConstants}.
+     */
+    private void onPayloadApplicationComplete(int errorCode) {
+        runOnUiThread(() -> {
+            final String state = UpdateEngineErrorCodes.isUpdateSucceeded(errorCode)
+                    ? "SUCCESS"
+                    : "FAILURE";
+            Log.i("UpdateEngine",
+                    "Completed - errorCode="
+                    + UpdateEngineErrorCodes.getCodeName(errorCode) + "/" + errorCode
+                    + " " + state);
+            Toast.makeText(this, "Update completed", Toast.LENGTH_LONG).show();
+        });
+    }
+
+    /** resets ui */
+    private void uiReset() {
+        mTextViewBuild.setText(Build.DISPLAY);
+        mSpinnerConfigs.setEnabled(true);
+        mButtonReload.setEnabled(true);
+        mButtonApplyConfig.setEnabled(true);
+        mButtonStop.setEnabled(false);
+        mButtonReset.setEnabled(false);
+        mProgressBar.setProgress(0);
+        mProgressBar.setEnabled(false);
+        mProgressBar.setVisibility(ProgressBar.INVISIBLE);
+        mTextViewStatus.setText(R.string.unknown);
+    }
+
+    /** sets ui updating mode */
+    private void uiSetUpdating() {
+        mTextViewBuild.setText(Build.DISPLAY);
+        mSpinnerConfigs.setEnabled(false);
+        mButtonReload.setEnabled(false);
+        mButtonApplyConfig.setEnabled(false);
+        mButtonStop.setEnabled(true);
+        mProgressBar.setEnabled(true);
+        mButtonReset.setEnabled(true);
+        mProgressBar.setVisibility(ProgressBar.VISIBLE);
+    }
+
+    /**
+     * loads json configurations from configs dir that is defined in {@link UpdateConfigs}.
+     */
+    private void loadUpdateConfigs() {
+        mConfigs = UpdateConfigs.getUpdateConfigs(this);
+        loadConfigsToSpinner(mConfigs);
+    }
+
+    /**
+     * @param status update engine status code
+     */
+    private void setUiStatus(int status) {
+        String statusText = UpdateEngineStatuses.getStatusText(status);
+        mTextViewStatus.setText(statusText);
+    }
+
+    private void loadConfigsToSpinner(List<UpdateConfig> configs) {
+        String[] spinnerArray = UpdateConfigs.configsToNames(configs);
+        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<>(this,
+                android.R.layout.simple_spinner_item,
+                spinnerArray);
+        spinnerArrayAdapter.setDropDownViewResource(android.R.layout
+                .simple_spinner_dropdown_item);
+        mSpinnerConfigs.setAdapter(spinnerArrayAdapter);
+    }
+
+    private UpdateConfig getSelectedConfig() {
+        return mConfigs.get(mSpinnerConfigs.getSelectedItemPosition());
+    }
+
+    /**
+     * Applies the given update
+     */
+    private void applyUpdate(UpdateConfig config) {
+        if (config.getInstallType() == UpdateConfig.TYPE_NON_STREAMING) {
+            AbNonStreamingUpdate update = new AbNonStreamingUpdate(mUpdateEngine, config);
+            try {
+                update.execute();
+            } catch (Exception e) {
+                Log.e("MainActivity", "Error applying the update", e);
+                Toast.makeText(this, "Error applying the update", Toast.LENGTH_SHORT)
+                        .show();
+            }
+        } else {
+            Toast.makeText(this, "Streaming is not implemented", Toast.LENGTH_SHORT)
+                    .show();
+        }
+    }
+
+    /**
+     * Requests update engine to stop any ongoing update. If an update has been applied,
+     * leave it as is.
+     */
+    private void stopRunningUpdate() {
+        Toast.makeText(this,
+                "stopRunningUpdate is not implemented",
+                Toast.LENGTH_SHORT).show();
+
+    }
+
+    /**
+     * Resets update engine to IDLE state. Requests to cancel any onging update, or to revert if an
+     * update has been applied.
+     */
+    private void resetUpdate() {
+        Toast.makeText(this,
+                "resetUpdate is not implemented",
+                Toast.LENGTH_SHORT).show();
+    }
+
+    /**
+     * Helper class to delegate UpdateEngine callbacks to MainActivity
+     */
+    class UpdateEngineCallbackImpl extends UpdateEngineCallback {
+        @Override
+        public void onStatusUpdate(int status, float percent) {
+            MainActivity.this.onStatusUpdate(status, percent);
+        }
+
+        @Override
+        public void onPayloadApplicationComplete(int errorCode) {
+            MainActivity.this.onPayloadApplicationComplete(errorCode);
+        }
+    }
+
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/updates/AbNonStreamingUpdate.java b/updater_sample/src/com/example/android/systemupdatersample/updates/AbNonStreamingUpdate.java
new file mode 100644
index 000000000..1b91a1ac3
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/updates/AbNonStreamingUpdate.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.updates;
+
+import android.os.UpdateEngine;
+
+import com.example.android.systemupdatersample.PayloadSpec;
+import com.example.android.systemupdatersample.UpdateConfig;
+import com.example.android.systemupdatersample.util.PayloadSpecs;
+
+/**
+ * Applies A/B (seamless) non-streaming update.
+ */
+public class AbNonStreamingUpdate {
+
+    private final UpdateEngine mUpdateEngine;
+    private final UpdateConfig mUpdateConfig;
+
+    public AbNonStreamingUpdate(UpdateEngine updateEngine, UpdateConfig config) {
+        this.mUpdateEngine = updateEngine;
+        this.mUpdateConfig = config;
+    }
+
+    /**
+     * Start applying the update. This method doesn't wait until end of the update.
+     * {@code update_engine} works asynchronously.
+     */
+    public void execute() throws Exception {
+        PayloadSpec payload = PayloadSpecs.forNonStreaming(mUpdateConfig.getUpdatePackageFile());
+
+        mUpdateEngine.applyPayload(
+                payload.getUrl(),
+                payload.getOffset(),
+                payload.getSize(),
+                payload.getProperties().toArray(new String[0]));
+    }
+
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/PackagePropertyFiles.java b/updater_sample/src/com/example/android/systemupdatersample/util/PackagePropertyFiles.java
new file mode 100644
index 000000000..3988b5928
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/PackagePropertyFiles.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+/** Utility class for property files in a package. */
+public final class PackagePropertyFiles {
+
+    public static final String PAYLOAD_BINARY_FILE_NAME = "payload.bin";
+
+    public static final String PAYLOAD_HEADER_FILE_NAME = "payload_header.bin";
+
+    public static final String PAYLOAD_METADATA_FILE_NAME = "payload_metadata.bin";
+
+    public static final String PAYLOAD_PROPERTIES_FILE_NAME = "payload_properties.txt";
+
+    /** The zip entry in an A/B OTA package, which will be used by update_verifier. */
+    public static final String CARE_MAP_FILE_NAME = "care_map.txt";
+
+    public static final String METADATA_FILE_NAME = "metadata";
+
+    /**
+     * The zip file that claims the compatibility of the update package to check against the Android
+     * framework to ensure that the package can be installed on the device.
+     */
+    public static final String COMPATIBILITY_ZIP_FILE_NAME = "compatibility.zip";
+
+    private PackagePropertyFiles() {}
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java b/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java
new file mode 100644
index 000000000..43c8d75e2
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/PayloadSpecs.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import android.annotation.TargetApi;
+import android.os.Build;
+
+import com.example.android.systemupdatersample.PayloadSpec;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+/** The helper class that creates {@link PayloadSpec}. */
+@TargetApi(Build.VERSION_CODES.N)
+public final class PayloadSpecs {
+
+    /**
+     * The payload PAYLOAD_ENTRY is stored in the zip package to comply with the Android OTA package
+     * format. We want to find out the offset of the entry, so that we can pass it over to the A/B
+     * updater without making an extra copy of the payload.
+     *
+     * <p>According to Android docs, the entries are listed in the order in which they appear in the
+     * zip file. So we enumerate the entries to identify the offset of the payload file.
+     * http://developer.android.com/reference/java/util/zip/ZipFile.html#entries()
+     */
+    public static PayloadSpec forNonStreaming(File packageFile) throws IOException {
+        boolean payloadFound = false;
+        long payloadOffset = 0;
+        long payloadSize = 0;
+
+        List<String> properties = new ArrayList<>();
+        try (ZipFile zip = new ZipFile(packageFile)) {
+            Enumeration<? extends ZipEntry> entries = zip.entries();
+            long offset = 0;
+            while (entries.hasMoreElements()) {
+                ZipEntry entry = entries.nextElement();
+                String name = entry.getName();
+                // Zip local file header has 30 bytes + filename + sizeof extra field.
+                // https://en.wikipedia.org/wiki/Zip_(file_format)
+                long extraSize = entry.getExtra() == null ? 0 : entry.getExtra().length;
+                offset += 30 + name.length() + extraSize;
+
+                if (entry.isDirectory()) {
+                    continue;
+                }
+
+                long length = entry.getCompressedSize();
+                if (PackagePropertyFiles.PAYLOAD_BINARY_FILE_NAME.equals(name)) {
+                    if (entry.getMethod() != ZipEntry.STORED) {
+                        throw new IOException("Invalid compression method.");
+                    }
+                    payloadFound = true;
+                    payloadOffset = offset;
+                    payloadSize = length;
+                } else if (PackagePropertyFiles.PAYLOAD_PROPERTIES_FILE_NAME.equals(name)) {
+                    InputStream inputStream = zip.getInputStream(entry);
+                    if (inputStream != null) {
+                        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
+                        String line;
+                        while ((line = br.readLine()) != null) {
+                            properties.add(line);
+                        }
+                    }
+                }
+                offset += length;
+            }
+        }
+
+        if (!payloadFound) {
+            throw new IOException("Failed to find payload entry in the given package.");
+        }
+        return PayloadSpec.newBuilder()
+                        .url("file://" + packageFile.getAbsolutePath())
+                        .offset(payloadOffset)
+                        .size(payloadSize)
+                        .properties(properties)
+                        .build();
+    }
+
+    /**
+     * Converts an {@link PayloadSpec} to a string.
+     */
+    public static String toString(PayloadSpec payloadSpec) {
+        return "<PayloadSpec url=" + payloadSpec.getUrl()
+                + ", offset=" + payloadSpec.getOffset()
+                + ", size=" + payloadSpec.getSize()
+                + ", properties=" + Arrays.toString(
+                        payloadSpec.getProperties().toArray(new String[0]))
+                + ">";
+    }
+
+    private PayloadSpecs() {}
+
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java
new file mode 100644
index 000000000..089f8b2f2
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import android.content.Context;
+
+import com.example.android.systemupdatersample.UpdateConfig;
+
+import java.io.File;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Utility class for working with json update configurations.
+ */
+public final class UpdateConfigs {
+
+    private static final String UPDATE_CONFIGS_ROOT = "configs/";
+
+    /**
+     * @param configs update configs
+     * @return list of names
+     */
+    public static String[] configsToNames(List<UpdateConfig> configs) {
+        return configs.stream().map(UpdateConfig::getName).toArray(String[]::new);
+    }
+
+    /**
+     * @param context app context
+     * @return configs root directory
+     */
+    public static String getConfigsRoot(Context context) {
+        return Paths.get(context.getFilesDir().toString(),
+                UPDATE_CONFIGS_ROOT).toString();
+    }
+
+    /**
+     * It parses only {@code .json} files.
+     *
+     * @param context application context
+     * @return list of configs from directory {@link UpdateConfigs#getConfigsRoot}
+     */
+    public static List<UpdateConfig> getUpdateConfigs(Context context) {
+        File root = new File(getConfigsRoot(context));
+        ArrayList<UpdateConfig> configs = new ArrayList<>();
+        if (!root.exists()) {
+            return configs;
+        }
+        for (final File f : root.listFiles()) {
+            if (!f.isDirectory() && f.getName().endsWith(".json")) {
+                try {
+                    String json = new String(Files.readAllBytes(f.toPath()),
+                            StandardCharsets.UTF_8);
+                    configs.add(UpdateConfig.fromJson(json));
+                } catch (Exception e) {
+                    throw new RuntimeException(
+                            "Can't read/parse config file " + f.getName(), e);
+                }
+            }
+        }
+        return configs;
+    }
+
+    private UpdateConfigs() {}
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java
new file mode 100644
index 000000000..e63da6298
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineErrorCodes.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import android.os.UpdateEngine;
+import android.util.SparseArray;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Helper class to work with update_engine's error codes.
+ * Many error codes are defined in  {@link UpdateEngine.ErrorCodeConstants},
+ * but you can find more in system/update_engine/common/error_code.h.
+ */
+public final class UpdateEngineErrorCodes {
+
+    /**
+    * Error code from the update engine. Values must agree with the ones in
+    * system/update_engine/common/error_code.h.
+    */
+    public static final int UPDATED_BUT_NOT_ACTIVE = 52;
+
+    private static final SparseArray<String> CODE_TO_NAME_MAP = new SparseArray<>();
+
+    static {
+        CODE_TO_NAME_MAP.put(0, "SUCCESS");
+        CODE_TO_NAME_MAP.put(1, "ERROR");
+        CODE_TO_NAME_MAP.put(4, "FILESYSTEM_COPIER_ERROR");
+        CODE_TO_NAME_MAP.put(5, "POST_INSTALL_RUNNER_ERROR");
+        CODE_TO_NAME_MAP.put(6, "PAYLOAD_MISMATCHED_TYPE_ERROR");
+        CODE_TO_NAME_MAP.put(7, "INSTALL_DEVICE_OPEN_ERROR");
+        CODE_TO_NAME_MAP.put(8, "KERNEL_DEVICE_OPEN_ERROR");
+        CODE_TO_NAME_MAP.put(9, "DOWNLOAD_TRANSFER_ERROR");
+        CODE_TO_NAME_MAP.put(10, "PAYLOAD_HASH_MISMATCH_ERROR");
+        CODE_TO_NAME_MAP.put(11, "PAYLOAD_SIZE_MISMATCH_ERROR");
+        CODE_TO_NAME_MAP.put(12, "DOWNLOAD_PAYLOAD_VERIFICATION_ERROR");
+        CODE_TO_NAME_MAP.put(20, "DOWNLOAD_STATE_INITIALIZATION_ERROR");
+        CODE_TO_NAME_MAP.put(48, "USER_CANCELLED");
+        CODE_TO_NAME_MAP.put(52, "UPDATED_BUT_NOT_ACTIVE");
+    }
+
+    /**
+     * Completion codes returned by update engine indicating that the update
+     * was successfully applied.
+     */
+    private static final Set<Integer> SUCCEEDED_COMPLETION_CODES = new HashSet<Integer>(
+            Arrays.asList(UpdateEngine.ErrorCodeConstants.SUCCESS,
+                    // UPDATED_BUT_NOT_ACTIVE is returned when the payload is
+                    // successfully applied but the
+                    // device won't switch to the new slot after the next boot.
+                    UPDATED_BUT_NOT_ACTIVE));
+
+    /**
+     * checks if update succeeded using errorCode
+     */
+    public static boolean isUpdateSucceeded(int errorCode) {
+        return SUCCEEDED_COMPLETION_CODES.contains(errorCode);
+    }
+
+    /**
+     * converts error code to error name
+     */
+    public static String getCodeName(int errorCode) {
+        return CODE_TO_NAME_MAP.get(errorCode);
+    }
+
+    private UpdateEngineErrorCodes() {}
+}
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineStatuses.java b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineStatuses.java
new file mode 100644
index 000000000..6203b201a
--- /dev/null
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateEngineStatuses.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import android.util.SparseArray;
+
+/**
+ * Helper class to work with update_engine's error codes.
+ * Many error codes are defined in  {@link UpdateEngine.UpdateStatusConstants},
+ * but you can find more in system/update_engine/common/error_code.h.
+ */
+public final class UpdateEngineStatuses {
+
+    private static final SparseArray<String> STATUS_MAP = new SparseArray<>();
+
+    static {
+        STATUS_MAP.put(0, "IDLE");
+        STATUS_MAP.put(1, "CHECKING_FOR_UPDATE");
+        STATUS_MAP.put(2, "UPDATE_AVAILABLE");
+        STATUS_MAP.put(3, "DOWNLOADING");
+        STATUS_MAP.put(4, "VERIFYING");
+        STATUS_MAP.put(5, "FINALIZING");
+        STATUS_MAP.put(6, "UPDATED_NEED_REBOOT");
+        STATUS_MAP.put(7, "REPORTING_ERROR_EVENT");
+        STATUS_MAP.put(8, "ATTEMPTING_ROLLBACK");
+        STATUS_MAP.put(9, "DISABLED");
+    }
+
+    /**
+     * converts status code to status name
+     */
+    public static String getStatusText(int status) {
+        return STATUS_MAP.get(status);
+    }
+
+    private UpdateEngineStatuses() {}
+}
diff --git a/updater_sample/tests/Android.mk b/updater_sample/tests/Android.mk
new file mode 100644
index 000000000..83082cda6
--- /dev/null
+++ b/updater_sample/tests/Android.mk
@@ -0,0 +1,32 @@
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+LOCAL_PATH := $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_PACKAGE_NAME := SystemUpdaterSampleTests
+LOCAL_SDK_VERSION := system_current
+LOCAL_MODULE_TAGS := tests
+LOCAL_JAVA_LIBRARIES := \
+    android.test.base.stubs \
+    android.test.runner.stubs
+LOCAL_STATIC_JAVA_LIBRARIES := android-support-test
+LOCAL_INSTRUMENTATION_FOR := SystemUpdaterSample
+LOCAL_PROGUARD_ENABLED := disabled
+
+LOCAL_SRC_FILES := $(call all-subdir-java-files)
+
+include $(BUILD_PACKAGE)
diff --git a/updater_sample/tests/AndroidManifest.xml b/updater_sample/tests/AndroidManifest.xml
new file mode 100644
index 000000000..2392bb3af
--- /dev/null
+++ b/updater_sample/tests/AndroidManifest.xml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2018 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+      package="com.example.android.systemupdatersample.tests">
+
+    <!-- We add an application tag here just so that we can indicate that
+         this package needs to link against the android.test library,
+         which is needed when building test cases. -->
+    <application>
+        <uses-library android:name="android.test.runner" />
+    </application>
+
+    <instrumentation android:name="android.support.test.runner.AndroidJUnitRunner"
+                     android:targetPackage="com.example.android.systemupdatersample"
+                     android:label="Tests for SystemUpdaterSample."/>
+
+</manifest>
diff --git a/updater_sample/tests/build.properties b/updater_sample/tests/build.properties
new file mode 100644
index 000000000..e0c39def1
--- /dev/null
+++ b/updater_sample/tests/build.properties
@@ -0,0 +1 @@
+tested.project.dir=..
diff --git a/updater_sample/tests/res/raw/ota_002_package.zip b/updater_sample/tests/res/raw/ota_002_package.zip
new file mode 100644
index 000000000..145c62e6a
--- /dev/null
+++ b/updater_sample/tests/res/raw/ota_002_package.zip
diff --git a/updater_sample/tests/res/raw/update_config_stream_001.json b/updater_sample/tests/res/raw/update_config_stream_001.json
new file mode 100644
index 000000000..965f737d7
--- /dev/null
+++ b/updater_sample/tests/res/raw/update_config_stream_001.json
@@ -0,0 +1,14 @@
+{
+    "name": "streaming-001",
+    "url": "http://foo.bar/update.zip",
+    "type": "STREAMING",
+    "streaming_metadata": {
+        "property_files": [
+            {
+                "filename": "payload.bin",
+                "offset": 531,
+                "size": 5012323
+            }
+        ]
+    }
+}
diff --git a/updater_sample/tests/res/raw/update_config_stream_002.json b/updater_sample/tests/res/raw/update_config_stream_002.json
new file mode 100644
index 000000000..f00f19ce6
--- /dev/null
+++ b/updater_sample/tests/res/raw/update_config_stream_002.json
@@ -0,0 +1,35 @@
+{
+    "__": "*** Generated using tools/gen_update_config.py ***",
+    "ab_install_type": "STREAMING",
+    "ab_streaming_metadata": {
+        "property_files": [
+            {
+                "filename": "payload.bin",
+                "offset": 41,
+                "size": 7
+            },
+            {
+                "filename": "payload_properties.txt",
+                "offset": 100,
+                "size": 18
+            },
+            {
+                "filename": "care_map.txt",
+                "offset": 160,
+                "size": 8
+            },
+            {
+                "filename": "compatibility.zip",
+                "offset": 215,
+                "size": 13
+            },
+            {
+                "filename": "metadata",
+                "offset": 287,
+                "size": 8
+            }
+        ]
+    },
+    "name": "S ota_002_package",
+    "url": "file:///data/sample-ota-packages/ota_002_package.zip"
+}
\ No newline at end of file
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java
new file mode 100644
index 000000000..87153715e
--- /dev/null
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+
+/**
+ * Tests for {@link UpdateConfig}
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class UpdateConfigTest {
+
+    private static final String JSON_NON_STREAMING =
+            "{\"name\": \"vip update\", \"url\": \"file:///builds/a.zip\", "
+            + " \"type\": \"NON_STREAMING\"}";
+
+    private static final String JSON_STREAMING =
+            "{\"name\": \"vip update 2\", \"url\": \"http://foo.bar/a.zip\", "
+            + "\"type\": \"STREAMING\"}";
+
+    @Rule
+    public final ExpectedException thrown = ExpectedException.none();
+
+    @Test
+    public void fromJson_parsesJsonConfigWithoutMetadata() throws Exception {
+        UpdateConfig config = UpdateConfig.fromJson(JSON_NON_STREAMING);
+        assertEquals("name is parsed", "vip update", config.getName());
+        assertEquals("stores raw json", JSON_NON_STREAMING, config.getRawJson());
+        assertSame("type is parsed", UpdateConfig.TYPE_NON_STREAMING, config.getInstallType());
+        assertEquals("url is parsed", "file:///builds/a.zip", config.getUrl());
+    }
+
+    @Test
+    public void getUpdatePackageFile_throwsErrorIfStreaming() throws Exception {
+        UpdateConfig config = UpdateConfig.fromJson(JSON_STREAMING);
+        thrown.expect(RuntimeException.class);
+        config.getUpdatePackageFile();
+    }
+
+    @Test
+    public void getUpdatePackageFile_throwsErrorIfNotAFile() throws Exception {
+        String json = "{\"name\": \"upd\", \"url\": \"http://foo.bar\","
+                + " \"type\": \"NON_STREAMING\"}";
+        UpdateConfig config = UpdateConfig.fromJson(json);
+        thrown.expect(RuntimeException.class);
+        config.getUpdatePackageFile();
+    }
+
+    @Test
+    public void getUpdatePackageFile_works() throws Exception {
+        UpdateConfig c = UpdateConfig.fromJson(JSON_NON_STREAMING);
+        assertEquals("correct path", "/builds/a.zip", c.getUpdatePackageFile().getAbsolutePath());
+    }
+
+}
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/ui/MainActivityTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/ui/MainActivityTest.java
new file mode 100644
index 000000000..01014168a
--- /dev/null
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/ui/MainActivityTest.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.ui;
+
+import static org.junit.Assert.assertNotNull;
+
+import android.support.test.filters.MediumTest;
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * Make sure that the main launcher activity opens up properly, which will be
+ * verified by {@link #activityLaunches}.
+ */
+@RunWith(AndroidJUnit4.class)
+@MediumTest
+public class MainActivityTest {
+
+    @Rule
+    public final ActivityTestRule<MainActivity> mActivityRule =
+            new ActivityTestRule<>(MainActivity.class);
+
+    /**
+     * Verifies that the activity under test can be launched.
+     */
+    @Test
+    public void activityLaunches() {
+        assertNotNull(mActivityRule.getActivity());
+    }
+}
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java
new file mode 100644
index 000000000..6f06ca3e1
--- /dev/null
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import static com.example.android.systemupdatersample.util.PackagePropertyFiles.PAYLOAD_BINARY_FILE_NAME;
+import static com.example.android.systemupdatersample.util.PackagePropertyFiles.PAYLOAD_PROPERTIES_FILE_NAME;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.example.android.systemupdatersample.PayloadSpec;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.zip.CRC32;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+/**
+ * Tests if PayloadSpecs parses update package zip file correctly.
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class PayloadSpecsTest {
+
+    private static final String PROPERTIES_CONTENTS = "k1=val1\nkey2=val2";
+    private static final String PAYLOAD_CONTENTS    = "hello\nworld";
+    private static final int PAYLOAD_SIZE           = PAYLOAD_CONTENTS.length();
+
+    private File mTestDir;
+
+    private Context mContext;
+
+    @Rule
+    public final ExpectedException thrown = ExpectedException.none();
+
+    @Before
+    public void setUp() {
+        mContext = InstrumentationRegistry.getTargetContext();
+
+        mTestDir = mContext.getFilesDir();
+    }
+
+    @Test
+    public void forNonStreaming_works() throws Exception {
+        File packageFile = createMockZipFile();
+        PayloadSpec spec = PayloadSpecs.forNonStreaming(packageFile);
+
+        assertEquals("correct url", "file://" + packageFile.getAbsolutePath(), spec.getUrl());
+        assertEquals("correct payload offset",
+                30 + PAYLOAD_BINARY_FILE_NAME.length(), spec.getOffset());
+        assertEquals("correct payload size", PAYLOAD_SIZE, spec.getSize());
+        assertArrayEquals("correct properties",
+                new String[]{"k1=val1", "key2=val2"}, spec.getProperties().toArray(new String[0]));
+    }
+
+    @Test
+    public void forNonStreaming_IOException() throws Exception {
+        thrown.expect(IOException.class);
+        PayloadSpecs.forNonStreaming(new File("/fake/news.zip"));
+    }
+
+    /**
+     * Creates package zip file that contains payload.bin and payload_properties.txt
+     */
+    private File createMockZipFile() throws IOException {
+        File testFile = new File(mTestDir, "test.zip");
+        try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(testFile))) {
+            // Add payload.bin entry.
+            ZipEntry entry = new ZipEntry(PAYLOAD_BINARY_FILE_NAME);
+            entry.setMethod(ZipEntry.STORED);
+            entry.setCompressedSize(PAYLOAD_SIZE);
+            entry.setSize(PAYLOAD_SIZE);
+            CRC32 crc = new CRC32();
+            crc.update(PAYLOAD_CONTENTS.getBytes(StandardCharsets.UTF_8));
+            entry.setCrc(crc.getValue());
+            zos.putNextEntry(entry);
+            zos.write(PAYLOAD_CONTENTS.getBytes(StandardCharsets.UTF_8));
+            zos.closeEntry();
+
+            // Add payload properties entry.
+            ZipEntry propertiesEntry = new ZipEntry(PAYLOAD_PROPERTIES_FILE_NAME);
+            zos.putNextEntry(propertiesEntry);
+            zos.write(PROPERTIES_CONTENTS.getBytes(StandardCharsets.UTF_8));
+            zos.closeEntry();
+        }
+        return testFile;
+    }
+
+}
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/util/UpdateConfigsTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/util/UpdateConfigsTest.java
new file mode 100644
index 000000000..4aa8c6453
--- /dev/null
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/util/UpdateConfigsTest.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.systemupdatersample.util;
+
+import static org.junit.Assert.assertArrayEquals;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.example.android.systemupdatersample.UpdateConfig;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Tests for {@link UpdateConfigs}
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class UpdateConfigsTest {
+
+    private Context mContext;
+
+    @Rule
+    public final ExpectedException thrown = ExpectedException.none();
+
+    @Before
+    public void setUp() {
+        mContext = InstrumentationRegistry.getTargetContext();
+    }
+
+    @Test
+    public void configsToNames_extractsNames() {
+        List<UpdateConfig> configs = Arrays.asList(
+                new UpdateConfig("blah", "http://", UpdateConfig.TYPE_NON_STREAMING),
+                new UpdateConfig("blah 2", "http://", UpdateConfig.TYPE_STREAMING)
+        );
+        String[] names = UpdateConfigs.configsToNames(configs);
+        assertArrayEquals(new String[] {"blah", "blah 2"}, names);
+    }
+}
diff --git a/updater_sample/tools/gen_update_config.py b/updater_sample/tools/gen_update_config.py
new file mode 100755
index 000000000..cb9bd0119
--- /dev/null
+++ b/updater_sample/tools/gen_update_config.py
@@ -0,0 +1,161 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Given a OTA package file, produces update config JSON file.
+
+Example:  tools/gen_update.config.py \\
+            --ab_install_type=STREAMING \\
+            ota-build-001.zip  \\
+            my-config-001.json \\
+            http://foo.bar/ota-builds/ota-build-001.zip
+"""
+
+import argparse
+import json
+import os.path
+import sys
+import zipfile
+
+
+class GenUpdateConfig(object):
+    """
+    A class that generates update configuration file from an OTA package.
+
+    Currently supports only A/B (seamless) OTA packages.
+    TODO: add non-A/B packages support.
+    """
+
+    AB_INSTALL_TYPE_STREAMING = 'STREAMING'
+    AB_INSTALL_TYPE_NON_STREAMING = 'NON_STREAMING'
+    METADATA_NAME = 'META-INF/com/android/metadata'
+
+    def __init__(self, package, url, ab_install_type):
+        self.package = package
+        self.url = url
+        self.ab_install_type = ab_install_type
+        self.streaming_required = (
+            # payload.bin and payload_properties.txt must exist.
+            'payload.bin',
+            'payload_properties.txt',
+        )
+        self.streaming_optional = (
+            # care_map.txt is available only if dm-verity is enabled.
+            'care_map.txt',
+            # compatibility.zip is available only if target supports Treble.
+            'compatibility.zip',
+        )
+        self._config = None
+
+    @property
+    def config(self):
+        """Returns generated config object."""
+        return self._config
+
+    def run(self):
+        """Generates config."""
+        streaming_metadata = None
+        if self.ab_install_type == GenUpdateConfig.AB_INSTALL_TYPE_STREAMING:
+            streaming_metadata = self._gen_ab_streaming_metadata()
+
+        self._config = {
+            '__': '*** Generated using tools/gen_update_config.py ***',
+            'name': self.ab_install_type[0] + ' ' + os.path.basename(self.package)[:-4],
+            'url': self.url,
+            'ab_streaming_metadata': streaming_metadata,
+            'ab_install_type': self.ab_install_type,
+        }
+
+    def _gen_ab_streaming_metadata(self):
+        """Builds metadata for files required for streaming update."""
+        with zipfile.ZipFile(self.package, 'r') as package_zip:
+            property_files = self._get_property_files(package_zip)
+
+            metadata = {
+                'property_files': property_files
+            }
+
+        return metadata
+
+    def _get_property_files(self, zip_file):
+        """Constructs the property-files list for A/B streaming metadata."""
+
+        def compute_entry_offset_size(name):
+            """Computes the zip entry offset and size."""
+            info = zip_file.getinfo(name)
+            offset = info.header_offset + len(info.FileHeader())
+            size = info.file_size
+            return {
+                'filename': os.path.basename(name),
+                'offset': offset,
+                'size': size,
+            }
+
+        property_files = []
+        for entry in self.streaming_required:
+            property_files.append(compute_entry_offset_size(entry))
+        for entry in self.streaming_optional:
+            if entry in zip_file.namelist():
+                property_files.append(compute_entry_offset_size(entry))
+
+        # 'META-INF/com/android/metadata' is required
+        property_files.append(compute_entry_offset_size(GenUpdateConfig.METADATA_NAME))
+
+        return property_files
+
+    def write(self, out):
+        """Writes config to the output file."""
+        with open(out, 'w') as out_file:
+            json.dump(self.config, out_file, indent=4, separators=(',', ': '), sort_keys=True)
+
+
+def main():  # pylint: disable=missing-docstring
+    ab_install_type_choices = [
+        GenUpdateConfig.AB_INSTALL_TYPE_STREAMING,
+        GenUpdateConfig.AB_INSTALL_TYPE_NON_STREAMING]
+    parser = argparse.ArgumentParser(description=__doc__,
+                                     formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('--ab_install_type',
+                        type=str,
+                        default=GenUpdateConfig.AB_INSTALL_TYPE_NON_STREAMING,
+                        choices=ab_install_type_choices,
+                        help='A/B update installation type')
+    parser.add_argument('package',
+                        type=str,
+                        help='OTA package zip file')
+    parser.add_argument('out',
+                        type=str,
+                        help='Update configuration JSON file')
+    parser.add_argument('url',
+                        type=str,
+                        help='OTA package download url')
+    args = parser.parse_args()
+
+    if not args.out.endswith('.json'):
+        print('out must be a json file')
+        sys.exit(1)
+
+    gen = GenUpdateConfig(
+        package=args.package,
+        url=args.url,
+        ab_install_type=args.ab_install_type)
+    gen.run()
+    gen.write(args.out)
+    print('Config is written to ' + args.out)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/updater_sample/tools/gen_update_config_test.py b/updater_sample/tools/gen_update_config_test.py
new file mode 100755
index 000000000..951d4c4a7
--- /dev/null
+++ b/updater_sample/tools/gen_update_config_test.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Tests gen_update_config.py
+"""
+
+import os.path
+import unittest
+from gen_update_config import GenUpdateConfig
+
+
+class GenUpdateConfigTest(unittest.TestCase): # pylint: disable=missing-docstring
+
+    def test_ab_install_type_streaming(self):
+        """tests if streaming property files' offset and size are generated properly"""
+        config, package = self._generate_config()
+        property_files = config['ab_streaming_metadata']['property_files']
+        self.assertEqual(len(property_files), 5)
+        with open(package, 'rb') as pkg_file:
+            for prop in property_files:
+                filename, offset, size = prop['filename'], prop['offset'], prop['size']
+                pkg_file.seek(offset)
+                data = pkg_file.read(size).decode('ascii')
+                # data in the archive are just uppercase filenames without extension
+                expected_data = filename.split('.')[0].upper()
+                self.assertEqual(data, expected_data)
+
+    @staticmethod
+    def _generate_config():
+        """Generates JSON config from ota_002_package.zip."""
+        ota_package = os.path.join(os.path.dirname(__file__),
+                                   '../tests/res/raw/ota_002_package.zip')
+        gen = GenUpdateConfig(ota_package,
+                              'file:///foo.bar',
+                              GenUpdateConfig.AB_INSTALL_TYPE_STREAMING)
+        gen.run()
+        return gen.config, ota_package
+
+
+if __name__ == '__main__':
+    unittest.main()