diff --git a/CleanSpec.mk b/CleanSpec.mk
index 1c02da6..757c513 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -617,6 +617,9 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/super.img)
 
 $(call add-clean-step, find $(PRODUCT_OUT) -type f -name "generated_*_image_info.txt" -print0 | xargs -0 rm -f)
+
+# Clean up libicuuc.so and libicui18n.so
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/lib*/libicu*)
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************
diff --git a/core/board_config.mk b/core/board_config.mk
index 9ea3509..d32e301 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -44,6 +44,7 @@
   TARGET_BOARD_PLATFORM \
   TARGET_BOARD_PLATFORM_GPU \
   TARGET_BOOTLOADER_BOARD_NAME \
+  TARGET_FS_CONFIG_GEN \
   TARGET_NO_BOOTLOADER \
   TARGET_NO_KERNEL \
   TARGET_NO_RECOVERY \
diff --git a/core/main.mk b/core/main.mk
index 3ff2fcd..590bfcc 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -218,8 +218,7 @@
 
 #
 # -----------------------------------------------------------------
-# Enable dynamic linker and hidden API developer warnings for
-# userdebug, eng and non-REL builds
+# Enable dynamic linker warnings for userdebug, eng and non-REL builds
 ifneq ($(TARGET_BUILD_VARIANT),user)
   ADDITIONAL_BUILD_PROPERTIES += ro.bionic.ld.warning=1
 else
@@ -257,6 +256,11 @@
 ADDITIONAL_PRODUCT_PROPERTIES += dalvik.vm.systemservercompilerfilter=$(PRODUCT_SYSTEM_SERVER_COMPILER_FILTER)
 endif
 
+# Enable core platform API violation warnings on userdebug and eng builds.
+ifneq ($(TARGET_BUILD_VARIANT),user)
+ADDITIONAL_BUILD_PROPERTIES += persist.debug.dalvik.vm.core_platform_api_policy=just-warn
+endif
+
 # Sets the default value of ro.postinstall.fstab.prefix to /system.
 # Device board config should override the value to /product when needed by:
 #
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 0275de6..c01fc98 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -165,6 +165,8 @@
 $(call add_json_list, ProductHiddenAPIStubsSystem,       $(PRODUCT_HIDDENAPI_STUBS_SYSTEM))
 $(call add_json_list, ProductHiddenAPIStubsTest,         $(PRODUCT_HIDDENAPI_STUBS_TEST))
 
+$(call add_json_str,  TargetFSConfigGen,                 $(TARGET_FS_CONFIG_GEN))
+
 $(call add_json_map, VendorVars)
 $(foreach namespace,$(SOONG_CONFIG_NAMESPACES),\
   $(call add_json_map, $(namespace))\
diff --git a/target/board/BoardConfigEmuCommon.mk b/target/board/BoardConfigEmuCommon.mk
index 617b3c5..c871d7e 100644
--- a/target/board/BoardConfigEmuCommon.mk
+++ b/target/board/BoardConfigEmuCommon.mk
@@ -20,6 +20,9 @@
 # the GLES renderer disables itself if host GL acceleration isn't available.
 USE_OPENGL_RENDERER := true
 
+# Emulator doesn't support sparse image format.
+TARGET_USERIMAGES_SPARSE_EXT_DISABLED := true
+
 # ~140 MB vendor image. Please adjust system image / vendor image sizes
 # when finalizing them. The partition size needs to be a multiple of image
 # block size: 4096.
diff --git a/target/board/BoardConfigGsiCommon.mk b/target/board/BoardConfigGsiCommon.mk
index eee65f4..d4025c3 100644
--- a/target/board/BoardConfigGsiCommon.mk
+++ b/target/board/BoardConfigGsiCommon.mk
@@ -11,11 +11,6 @@
 # This flag is set by mainline but isn't desired for GSI.
 BOARD_USES_SYSTEM_OTHER_ODEX :=
 
-# GSIs are historically released in sparse format.
-# Some vendors' bootloaders don't work properly with raw format images. So
-# we explicit specify this need below (even though it's the current default).
-TARGET_USERIMAGES_SPARSE_EXT_DISABLED := false
-
 # system.img is always ext4 with sparse option
 # GSI also includes make_f2fs to support userdata parition in f2fs
 # for some devices
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 87076a9..46bf350 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -356,6 +356,7 @@
     showmap \
     sqlite3 \
     ss \
+    start_with_lockagent \
     strace \
     su \
     sanitizer-status \
diff --git a/target/product/mainline_system.mk b/target/product/mainline_system.mk
index ecd5691..d75809c 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/mainline_system.mk
@@ -76,6 +76,7 @@
     android.hardware.secure_element@1.0 \
     android.hardware.wifi@1.0 \
     libaudio-resampler \
+    libdrm \
     liblogwrap \
     liblz4 \
     libminui \
diff --git a/target/product/runtime_libart.mk b/target/product/runtime_libart.mk
index dbb4b82..e08b56b 100644
--- a/target/product/runtime_libart.mk
+++ b/target/product/runtime_libart.mk
@@ -33,11 +33,6 @@
 PRODUCT_PACKAGES += \
     ext \
 
-# Libcore ICU. TODO(b/124218500): Remove them explicitly when the bug is resolved.
-PRODUCT_PACKAGES += \
-    libicui18n \
-    libicuuc \
-
 # Android Runtime APEX module.
 PRODUCT_PACKAGES += com.android.runtime
 PRODUCT_HOST_PACKAGES += com.android.runtime
diff --git a/tools/fs_config/Android.bp b/tools/fs_config/Android.bp
index 19a4624..d6fae2d 100644
--- a/tools/fs_config/Android.bp
+++ b/tools/fs_config/Android.bp
@@ -12,6 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+bootstrap_go_package {
+    name: "soong-fs_config",
+    pkgPath: "android/soong/fs_config",
+    deps: [
+        "soong-android",
+        "soong-genrule",
+    ],
+    srcs: [
+        "fs_config.go"
+    ],
+    pluginFor: ["soong_build"],
+}
+
 cc_binary_host {
     name: "fs_config",
     srcs: ["fs_config.c"],
@@ -21,3 +34,64 @@
     ],
     cflags: ["-Werror"],
 }
+
+target_fs_config_gen_filegroup {
+    name: "target_fs_config_gen",
+}
+
+genrule {
+    name: "oemaids_header_gen",
+    tool_files: ["fs_config_generator.py"],
+    cmd: "$(location fs_config_generator.py) oemaid --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    srcs: [
+        ":target_fs_config_gen",
+        ":android_filesystem_config_header",
+    ],
+    out: ["generated_oem_aid.h"],
+}
+
+cc_library_headers {
+    name: "oemaids_headers",
+    generated_headers: ["oemaids_header_gen"],
+    export_generated_headers: ["oemaids_header_gen"],
+}
+
+// Generate the vendor/etc/passwd text file for the target
+// This file may be empty if no AIDs are defined in
+// TARGET_FS_CONFIG_GEN files.
+genrule {
+    name: "passwd_gen",
+    tool_files: ["fs_config_generator.py"],
+    cmd: "$(location fs_config_generator.py) passwd --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    srcs: [
+        ":target_fs_config_gen",
+        ":android_filesystem_config_header",
+    ],
+    out: ["passwd"],
+}
+
+prebuilt_etc {
+    name: "passwd",
+    vendor: true,
+    src: ":passwd_gen",
+}
+
+// Generate the vendor/etc/group text file for the target
+// This file may be empty if no AIDs are defined in
+// TARGET_FS_CONFIG_GEN files.
+genrule {
+    name: "group_gen",
+    tool_files: ["fs_config_generator.py"],
+    cmd: "$(location fs_config_generator.py) group --required-prefix=vendor_ --aid-header=$(location :android_filesystem_config_header) $(location :target_fs_config_gen) >$(out)",
+    srcs: [
+        ":target_fs_config_gen",
+        ":android_filesystem_config_header",
+    ],
+    out: ["group"],
+}
+
+prebuilt_etc {
+    name: "group",
+    vendor: true,
+    src: ":group_gen",
+}
diff --git a/tools/fs_config/Android.mk b/tools/fs_config/Android.mk
index 0e0b1da..96db0f3 100644
--- a/tools/fs_config/Android.mk
+++ b/tools/fs_config/Android.mk
@@ -382,67 +382,6 @@
 	   $(or $(PRIVATE_TARGET_FS_CONFIG_GEN),/dev/null)
 endif
 
-##################################
-# Build the oemaid header library when fs config files are present.
-# Intentionally break build if you require generated AIDs
-# header file, but are not using any fs config files.
-ifneq ($(TARGET_FS_CONFIG_GEN),)
-include $(CLEAR_VARS)
-LOCAL_MODULE := oemaids_headers
-
-LOCAL_MODULE_CLASS := ETC
-
-# Generate the "generated_oem_aid.h" file
-oem := $(local-generated-sources-dir)/generated_oem_aid.h
-$(oem): PRIVATE_LOCAL_PATH := $(LOCAL_PATH)
-$(oem): PRIVATE_TARGET_FS_CONFIG_GEN := $(TARGET_FS_CONFIG_GEN)
-$(oem): PRIVATE_ANDROID_FS_HDR := $(system_android_filesystem_config)
-$(oem): PRIVATE_CUSTOM_TOOL = $(PRIVATE_LOCAL_PATH)/fs_config_generator.py oemaid --aid-header=$(PRIVATE_ANDROID_FS_HDR) $(PRIVATE_TARGET_FS_CONFIG_GEN) > $@
-$(oem): $(TARGET_FS_CONFIG_GEN) $(LOCAL_PATH)/fs_config_generator.py
-	$(transform-generated-source)
-
-LOCAL_EXPORT_C_INCLUDE_DIRS := $(dir $(oem))
-LOCAL_EXPORT_C_INCLUDE_DEPS := $(oem)
-
-include $(BUILD_HEADER_LIBRARY)
-endif
-
-##################################
-# Generate the vendor/etc/passwd text file for the target
-# This file may be empty if no AIDs are defined in
-# TARGET_FS_CONFIG_GEN files.
-include $(CLEAR_VARS)
-
-LOCAL_MODULE := passwd
-LOCAL_MODULE_CLASS := ETC
-LOCAL_VENDOR_MODULE := true
-
-include $(BUILD_SYSTEM)/base_rules.mk
-
-$(LOCAL_BUILT_MODULE): PRIVATE_TARGET_FS_CONFIG_GEN := $(TARGET_FS_CONFIG_GEN)
-$(LOCAL_BUILT_MODULE): PRIVATE_ANDROID_FS_HDR := $(system_android_filesystem_config)
-$(LOCAL_BUILT_MODULE): $(LOCAL_PATH)/fs_config_generator.py $(TARGET_FS_CONFIG_GEN) $(system_android_filesystem_config)
-	@mkdir -p $(dir $@)
-	$(hide) $< passwd --required-prefix=vendor_ --aid-header=$(PRIVATE_ANDROID_FS_HDR) $(or $(PRIVATE_TARGET_FS_CONFIG_GEN),/dev/null) > $@
-
-##################################
-# Generate the vendor/etc/group text file for the target
-# This file may be empty if no AIDs are defined in
-# TARGET_FS_CONFIG_GEN files.
-include $(CLEAR_VARS)
-
-LOCAL_MODULE := group
-LOCAL_MODULE_CLASS := ETC
-LOCAL_VENDOR_MODULE := true
-
-include $(BUILD_SYSTEM)/base_rules.mk
-
-$(LOCAL_BUILT_MODULE): PRIVATE_TARGET_FS_CONFIG_GEN := $(TARGET_FS_CONFIG_GEN)
-$(LOCAL_BUILT_MODULE): PRIVATE_ANDROID_FS_HDR := $(system_android_filesystem_config)
-$(LOCAL_BUILT_MODULE): $(LOCAL_PATH)/fs_config_generator.py $(TARGET_FS_CONFIG_GEN) $(system_android_filesystem_config)
-	@mkdir -p $(dir $@)
-	$(hide) $< group --required-prefix=vendor_ --aid-header=$(PRIVATE_ANDROID_FS_HDR) $(or $(PRIVATE_TARGET_FS_CONFIG_GEN),/dev/null) > $@
-
 system_android_filesystem_config :=
 system_capability_header :=
 fs_config_generate_extra_partition_list :=
diff --git a/tools/fs_config/fs_config.go b/tools/fs_config/fs_config.go
new file mode 100644
index 0000000..869cb3d
--- /dev/null
+++ b/tools/fs_config/fs_config.go
@@ -0,0 +1,60 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fs_config
+
+import (
+	"android/soong/android"
+)
+
+var pctx = android.NewPackageContext("android/soong/fs_config")
+
+func init() {
+	android.RegisterModuleType("target_fs_config_gen_filegroup", targetFSConfigGenFactory)
+}
+
+// target_fs_config_gen_filegroup is used to expose the file pointed to by TARGET_FS_CONFIG_GEN to
+// genrules in Soong. If TARGET_FS_CONFIG_GEN is empty, it will export an empty file instead.
+func targetFSConfigGenFactory() android.Module {
+	module := &targetFSConfigGen{}
+	android.InitAndroidModule(module)
+	return module
+}
+
+var _ android.SourceFileProducer = (*targetFSConfigGen)(nil)
+
+type targetFSConfigGen struct {
+	android.ModuleBase
+	path android.Path
+}
+
+func (targetFSConfigGen) DepsMutator(ctx android.BottomUpMutatorContext) {}
+
+func (t *targetFSConfigGen) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	if ret := ctx.DeviceConfig().TargetFSConfigGen(); ret != nil && *ret != "" {
+		t.path = android.PathForSource(ctx, *ret)
+	} else {
+		path := android.PathForModuleGen(ctx, "empty")
+		t.path = path
+
+		rule := android.NewRuleBuilder()
+		rule.Command().Text("rm -rf").Output(path)
+		rule.Command().Text("touch").Output(path)
+		rule.Build(pctx, ctx, "fs_config_empty", "create empty file")
+	}
+}
+
+func (t *targetFSConfigGen) Srcs() android.Paths {
+	return android.Paths{t.path}
+}
diff --git a/tools/releasetools/Android.bp b/tools/releasetools/Android.bp
new file mode 100644
index 0000000..b5ae009
--- /dev/null
+++ b/tools/releasetools/Android.bp
@@ -0,0 +1,72 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+python_defaults {
+    name: "releasetools_test_defaults",
+    version: {
+        py2: {
+            enabled: true,
+            embedded_launcher: false,
+        },
+        py3: {
+            enabled: false,
+        },
+    },
+}
+
+python_library_host {
+    name: "releasetools_lib",
+    defaults: ["releasetools_test_defaults"],
+    srcs: [
+        "add_img_to_target_files.py",
+        "apex_utils.py",
+        "blockimgdiff.py",
+        "build_image.py",
+        "build_super_image.py",
+        "check_ota_package_signature.py",
+        "check_target_files_signatures.py",
+        "common.py",
+        "edify_generator.py",
+        "img_from_target_files.py",
+        "make_recovery_patch.py",
+        "merge_target_files.py",
+        "ota_from_target_files.py",
+        "ota_package_parser.py",
+        "rangelib.py",
+        "sign_target_files_apks.py",
+        "sparse_img.py",
+        "target_files_diff.py",
+        "validate_target_files.py",
+        "verity_utils.py",
+    ],
+}
+
+python_test_host {
+    name: "releasetools_test",
+    defaults: ["releasetools_test_defaults"],
+    main: "test_utils.py",
+    srcs: [
+        "test_*.py",
+    ],
+    libs: [
+        "releasetools_lib",
+    ],
+    data: [
+        "testdata/*",
+    ],
+    required: [
+        "otatools",
+    ],
+    test_suites: ["general-tests"],
+}
diff --git a/tools/releasetools/TEST_MAPPING b/tools/releasetools/TEST_MAPPING
new file mode 100644
index 0000000..77cef07
--- /dev/null
+++ b/tools/releasetools/TEST_MAPPING
@@ -0,0 +1,8 @@
+{
+  "presubmit": [
+    {
+      "name": "releasetools_test",
+      "host": true
+    }
+  ]
+}
diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index b7c33f5..b23eef1 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -187,6 +187,83 @@
       fd.write(data)
 
 
+class FileImage(Image):
+  """An image wrapped around a raw image file."""
+
+  def __init__(self, path, hashtree_info_generator=None):
+    self.path = path
+    self.blocksize = 4096
+    self._file_size = os.path.getsize(self.path)
+    self._file = open(self.path, 'r')
+
+    if self._file_size % self.blocksize != 0:
+      raise ValueError("Size of file %s must be multiple of %d bytes, but is %d"
+                       % self.path, self.blocksize, self._file_size)
+
+    self.total_blocks = self._file_size / self.blocksize
+    self.care_map = RangeSet(data=(0, self.total_blocks))
+    self.clobbered_blocks = RangeSet()
+    self.extended = RangeSet()
+
+    self.generator_lock = threading.Lock()
+
+    self.hashtree_info = None
+    if hashtree_info_generator:
+      self.hashtree_info = hashtree_info_generator.Generate(self)
+
+    zero_blocks = []
+    nonzero_blocks = []
+    reference = '\0' * self.blocksize
+
+    for i in range(self.total_blocks):
+      d = self._file.read(self.blocksize)
+      if d == reference:
+        zero_blocks.append(i)
+        zero_blocks.append(i+1)
+      else:
+        nonzero_blocks.append(i)
+        nonzero_blocks.append(i+1)
+
+    assert zero_blocks or nonzero_blocks
+
+    self.file_map = {}
+    if zero_blocks:
+      self.file_map["__ZERO"] = RangeSet(data=zero_blocks)
+    if nonzero_blocks:
+      self.file_map["__NONZERO"] = RangeSet(data=nonzero_blocks)
+    if self.hashtree_info:
+      self.file_map["__HASHTREE"] = self.hashtree_info.hashtree_range
+
+  def __del__(self):
+    self._file.close()
+
+  def _GetRangeData(self, ranges):
+    # Use a lock to protect the generator so that we will not run two
+    # instances of this generator on the same object simultaneously.
+    with self.generator_lock:
+      for s, e in ranges:
+        self._file.seek(s * self.blocksize)
+        for _ in range(s, e):
+          yield self._file.read(self.blocksize)
+
+  def RangeSha1(self, ranges):
+    h = sha1()
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      h.update(data)
+    return h.hexdigest()
+
+  def ReadRangeSet(self, ranges):
+    return list(self._GetRangeData(ranges))
+
+  def TotalSha1(self, include_clobbered_blocks=False):
+    assert not self.clobbered_blocks
+    return self.RangeSha1(self.care_map)
+
+  def WriteRangeDataToFd(self, ranges, fd):
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      fd.write(data)
+
+
 class Transfer(object):
   def __init__(self, tgt_name, src_name, tgt_ranges, src_ranges, tgt_sha1,
                src_sha1, style, by_id):
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 171c794..3e2a113 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -824,6 +824,77 @@
   return tmp
 
 
+def GetUserImage(which, tmpdir, input_zip,
+                 info_dict=None,
+                 allow_shared_blocks=None,
+                 hashtree_info_generator=None,
+                 reset_file_map=False):
+  """Returns an Image object suitable for passing to BlockImageDiff.
+
+  This function loads the specified image from the given path. If the specified
+  image is sparse, it also performs additional processing for OTA purpose. For
+  example, it always adds block 0 to clobbered blocks list. It also detects
+  files that cannot be reconstructed from the block list, for whom we should
+  avoid applying imgdiff.
+
+  Args:
+    which: The partition name.
+    tmpdir: The directory that contains the prebuilt image and block map file.
+    input_zip: The target-files ZIP archive.
+    info_dict: The dict to be looked up for relevant info.
+    allow_shared_blocks: If image is sparse, whether having shared blocks is
+        allowed. If none, it is looked up from info_dict.
+    hashtree_info_generator: If present and image is sparse, generates the
+        hashtree_info for this sparse image.
+    reset_file_map: If true and image is sparse, reset file map before returning
+        the image.
+  Returns:
+    A Image object. If it is a sparse image and reset_file_map is False, the
+    image will have file_map info loaded.
+  """
+  if info_dict == None:
+    info_dict = LoadInfoDict(input_zip)
+
+  is_sparse = info_dict.get("extfs_sparse_flag")
+
+  # When target uses 'BOARD_EXT4_SHARE_DUP_BLOCKS := true', images may contain
+  # shared blocks (i.e. some blocks will show up in multiple files' block
+  # list). We can only allocate such shared blocks to the first "owner", and
+  # disable imgdiff for all later occurrences.
+  if allow_shared_blocks is None:
+    allow_shared_blocks = info_dict.get("ext4_share_dup_blocks") == "true"
+
+  if is_sparse:
+    img = GetSparseImage(which, tmpdir, input_zip, allow_shared_blocks,
+                         hashtree_info_generator)
+    if reset_file_map:
+      img.ResetFileMap()
+    return img
+  else:
+    return GetNonSparseImage(which, tmpdir, hashtree_info_generator)
+
+
+def GetNonSparseImage(which, tmpdir, hashtree_info_generator=None):
+  """Returns a Image object suitable for passing to BlockImageDiff.
+
+  This function loads the specified non-sparse image from the given path.
+
+  Args:
+    which: The partition name.
+    tmpdir: The directory that contains the prebuilt image and block map file.
+  Returns:
+    A Image object.
+  """
+  path = os.path.join(tmpdir, "IMAGES", which + ".img")
+  mappath = os.path.join(tmpdir, "IMAGES", which + ".map")
+
+  # The image and map files must have been created prior to calling
+  # ota_from_target_files.py (since LMP).
+  assert os.path.exists(path) and os.path.exists(mappath)
+
+  return blockimgdiff.FileImage(path, hashtree_info_generator=
+                                hashtree_info_generator)
+
 def GetSparseImage(which, tmpdir, input_zip, allow_shared_blocks,
                    hashtree_info_generator=None):
   """Returns a SparseImage object suitable for passing to BlockImageDiff.
@@ -2068,7 +2139,7 @@
 
 
 DataImage = blockimgdiff.DataImage
-
+EmptyImage = blockimgdiff.EmptyImage
 
 # map recovery.fstab's fs_types to mount/format "partition types"
 PARTITION_TYPES = {
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index ad40bd4..dd3e190 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -917,17 +917,14 @@
 
   script.ShowProgress(system_progress, 0)
 
-  # See the notes in WriteBlockIncrementalOTAPackage().
-  allow_shared_blocks = target_info.get('ext4_share_dup_blocks') == "true"
-
   def GetBlockDifference(partition):
     # Full OTA is done as an "incremental" against an empty source image. This
     # has the effect of writing new data from the package to the entire
     # partition, but lets us reuse the updater code that writes incrementals to
     # do it.
-    tgt = common.GetSparseImage(partition, OPTIONS.input_tmp, input_zip,
-                                allow_shared_blocks)
-    tgt.ResetFileMap()
+    tgt = common.GetUserImage(partition, OPTIONS.input_tmp, input_zip,
+                              info_dict=target_info,
+                              reset_file_map=True)
     diff = common.BlockDifference(partition, tgt, src=None)
     return diff
 
@@ -1512,8 +1509,10 @@
   device_specific = common.DeviceSpecificParams(
       source_zip=source_zip,
       source_version=source_api_version,
+      source_tmp=OPTIONS.source_tmp,
       target_zip=target_zip,
       target_version=target_api_version,
+      target_tmp=OPTIONS.target_tmp,
       output_zip=output_zip,
       script=script,
       metadata=metadata,
@@ -1529,20 +1528,20 @@
   target_recovery = common.GetBootableImage(
       "/tmp/recovery.img", "recovery.img", OPTIONS.target_tmp, "RECOVERY")
 
-  # When target uses 'BOARD_EXT4_SHARE_DUP_BLOCKS := true', images may contain
-  # shared blocks (i.e. some blocks will show up in multiple files' block
-  # list). We can only allocate such shared blocks to the first "owner", and
-  # disable imgdiff for all later occurrences.
+  # See notes in common.GetUserImage()
   allow_shared_blocks = (source_info.get('ext4_share_dup_blocks') == "true" or
                          target_info.get('ext4_share_dup_blocks') == "true")
-  system_src = common.GetSparseImage("system", OPTIONS.source_tmp, source_zip,
-                                     allow_shared_blocks)
+  system_src = common.GetUserImage("system", OPTIONS.source_tmp, source_zip,
+                                   info_dict=source_info,
+                                   allow_shared_blocks=allow_shared_blocks)
 
   hashtree_info_generator = verity_utils.CreateHashtreeInfoGenerator(
       "system", 4096, target_info)
-  system_tgt = common.GetSparseImage("system", OPTIONS.target_tmp, target_zip,
-                                     allow_shared_blocks,
-                                     hashtree_info_generator)
+  system_tgt = common.GetUserImage("system", OPTIONS.target_tmp, target_zip,
+                                   info_dict=target_info,
+                                   allow_shared_blocks=allow_shared_blocks,
+                                   hashtree_info_generator=
+                                   hashtree_info_generator)
 
   blockimgdiff_version = max(
       int(i) for i in target_info.get("blockimgdiff_versions", "1").split(","))
@@ -1567,13 +1566,16 @@
   if HasVendorPartition(target_zip):
     if not HasVendorPartition(source_zip):
       raise RuntimeError("can't generate incremental that adds /vendor")
-    vendor_src = common.GetSparseImage("vendor", OPTIONS.source_tmp, source_zip,
-                                       allow_shared_blocks)
+    vendor_src = common.GetUserImage("vendor", OPTIONS.source_tmp, source_zip,
+                                     info_dict=source_info,
+                                     allow_shared_blocks=allow_shared_blocks)
     hashtree_info_generator = verity_utils.CreateHashtreeInfoGenerator(
         "vendor", 4096, target_info)
-    vendor_tgt = common.GetSparseImage(
-        "vendor", OPTIONS.target_tmp, target_zip, allow_shared_blocks,
-        hashtree_info_generator)
+    vendor_tgt = common.GetUserImage(
+        "vendor", OPTIONS.target_tmp, target_zip,
+        info_dict=target_info,
+        allow_shared_blocks=allow_shared_blocks,
+        hashtree_info_generator=hashtree_info_generator)
 
     # Check first block of vendor partition for remount R/W only if
     # disk type is ext4
diff --git a/tools/releasetools/test_add_img_to_target_files.py b/tools/releasetools/test_add_img_to_target_files.py
index 482f86c..013ade6 100644
--- a/tools/releasetools/test_add_img_to_target_files.py
+++ b/tools/releasetools/test_add_img_to_target_files.py
@@ -34,18 +34,6 @@
   def setUp(self):
     OPTIONS.input_tmp = common.MakeTempDir()
 
-  def _verifyCareMap(self, expected, file_name):
-    """Parses the care_map.pb; and checks the content in plain text."""
-    text_file = common.MakeTempFile(prefix="caremap-", suffix=".txt")
-
-    # Calls an external binary to convert the proto message.
-    cmd = ["care_map_generator", "--parse_proto", file_name, text_file]
-    common.RunAndCheckOutput(cmd)
-
-    with open(text_file, 'r') as verify_fp:
-      plain_text = verify_fp.read()
-    self.assertEqual('\n'.join(expected), plain_text)
-
   @staticmethod
   def _create_images(images, prefix):
     """Creates images under OPTIONS.input_tmp/prefix."""
@@ -164,6 +152,19 @@
     }
     return image_paths
 
+  def _verifyCareMap(self, expected, file_name):
+    """Parses the care_map.pb; and checks the content in plain text."""
+    text_file = common.MakeTempFile(prefix="caremap-", suffix=".txt")
+
+    # Calls an external binary to convert the proto message.
+    cmd = ["care_map_generator", "--parse_proto", file_name, text_file]
+    common.RunAndCheckOutput(cmd)
+
+    with open(text_file) as verify_fp:
+      plain_text = verify_fp.read()
+    self.assertEqual('\n'.join(expected), plain_text)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta(self):
     image_paths = self._test_AddCareMapForAbOta()
 
@@ -179,6 +180,7 @@
 
     self._verifyCareMap(expected, care_map_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_withNonCareMapPartitions(self):
     """Partitions without care_map should be ignored."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -196,6 +198,7 @@
 
     self._verifyCareMap(expected, care_map_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_withAvb(self):
     """Tests the case for device using AVB."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -223,6 +226,7 @@
 
     self._verifyCareMap(expected, care_map_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_noFingerprint(self):
     """Tests the case for partitions without fingerprint."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -240,6 +244,7 @@
 
     self._verifyCareMap(expected, care_map_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_withThumbprint(self):
     """Tests the case for partitions with thumbprint."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -282,6 +287,7 @@
     self.assertRaises(AssertionError, AddCareMapForAbOta, None,
                       ['system', 'vendor'], image_paths)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_zipOutput(self):
     """Tests the case with ZIP output."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -304,6 +310,7 @@
                 "google/sailfish/678:user/dev-keys"]
     self._verifyCareMap(expected, os.path.join(temp_dir, care_map_name))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AddCareMapForAbOta_zipOutput_careMapEntryExists(self):
     """Tests the case with ZIP output which already has care_map entry."""
     image_paths = self._test_AddCareMapForAbOta()
@@ -338,6 +345,7 @@
     self.assertEqual(
         ['--include_descriptors_from_image', '/path/to/system.img'], cmd)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_AppendVBMetaArgsForPartition_vendorAsChainedPartition(self):
     testdata_dir = test_utils.get_testdata_dir()
     pubkey = os.path.join(testdata_dir, 'testkey.pubkey.pem')
diff --git a/tools/releasetools/test_apex_utils.py b/tools/releasetools/test_apex_utils.py
index 2f8ee49..c7d5807 100644
--- a/tools/releasetools/test_apex_utils.py
+++ b/tools/releasetools/test_apex_utils.py
@@ -39,6 +39,7 @@
       payload_fp.write(os.urandom(8192))
     return payload_file
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ParseApexPayloadInfo(self):
     payload_file = self._GetTestPayload()
     apex_utils.SignApexPayload(
@@ -48,16 +49,20 @@
     self.assertEqual(self.SALT, payload_info['Salt'])
     self.assertEqual('testkey', payload_info['apex.key'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_SignApexPayload(self):
     payload_file = self._GetTestPayload()
     apex_utils.SignApexPayload(
         payload_file, self.payload_key, 'testkey', 'SHA256_RSA2048', self.SALT)
     apex_utils.VerifyApexPayload(payload_file, self.payload_key)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_SignApexPayload_withSignerHelper(self):
     payload_file = self._GetTestPayload()
+    signing_helper = os.path.join(self.testdata_dir, 'signing_helper.sh')
+    os.chmod(signing_helper, 0o700)
     payload_signer_args = '--signing_helper_with_files {}'.format(
-        os.path.join(self.testdata_dir, 'signing_helper.sh'))
+        signing_helper)
     apex_utils.SignApexPayload(
         payload_file,
         self.payload_key,
@@ -65,6 +70,7 @@
         payload_signer_args)
     apex_utils.VerifyApexPayload(payload_file, self.payload_key)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_SignApexPayload_invalidKey(self):
     self.assertRaises(
         apex_utils.ApexSigningError,
@@ -75,6 +81,7 @@
         'SHA256_RSA2048',
         self.SALT)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_VerifyApexPayload_wrongKey(self):
     payload_file = self._GetTestPayload()
     apex_utils.SignApexPayload(
diff --git a/tools/releasetools/test_blockimgdiff.py b/tools/releasetools/test_blockimgdiff.py
index 1aabaa2..b6d47d4 100644
--- a/tools/releasetools/test_blockimgdiff.py
+++ b/tools/releasetools/test_blockimgdiff.py
@@ -14,9 +14,13 @@
 # limitations under the License.
 #
 
+import os
+from hashlib import sha1
+
 import common
 from blockimgdiff import (
-    BlockImageDiff, DataImage, EmptyImage, HeapItem, ImgdiffStats, Transfer)
+    BlockImageDiff, DataImage, EmptyImage, FileImage, HeapItem, ImgdiffStats,
+    Transfer)
 from rangelib import RangeSet
 from test_utils import ReleaseToolsTestCase
 
@@ -264,7 +268,42 @@
 
 
 class DataImageTest(ReleaseToolsTestCase):
-    def test_read_range_set(self):
-        data = "file" + ('\0' * 4092)
-        image = DataImage(data)
-        self.assertEqual(data, "".join(image.ReadRangeSet(image.care_map)))
+  def test_read_range_set(self):
+    data = "file" + ('\0' * 4092)
+    image = DataImage(data)
+    self.assertEqual(data, "".join(image.ReadRangeSet(image.care_map)))
+
+
+class FileImageTest(ReleaseToolsTestCase):
+  def setUp(self):
+    self.file_path = common.MakeTempFile()
+    self.data = os.urandom(4096 * 4)
+    with open(self.file_path, 'w') as f:
+      f.write(self.data)
+    self.file = FileImage(self.file_path)
+
+  def test_totalsha1(self):
+    self.assertEqual(sha1(self.data).hexdigest(), self.file.TotalSha1())
+
+  def test_ranges(self):
+    blocksize = self.file.blocksize
+    for s in range(4):
+      for e in range(s, 4):
+        expected_data = self.data[s * blocksize : e * blocksize]
+
+        rs = RangeSet([s, e])
+        data = "".join(self.file.ReadRangeSet(rs))
+        self.assertEqual(expected_data, data)
+
+        sha1sum = self.file.RangeSha1(rs)
+        self.assertEqual(sha1(expected_data).hexdigest(), sha1sum)
+
+        tmpfile = common.MakeTempFile()
+        with open(tmpfile, 'w') as f:
+          self.file.WriteRangeDataToFd(rs, f)
+        with open(tmpfile, 'r') as f:
+          self.assertEqual(expected_data, f.read())
+
+  def test_read_all(self):
+    data = "".join(self.file.ReadRangeSet(self.file.care_map))
+    self.assertEqual(self.data, data)
diff --git a/tools/releasetools/test_build_image.py b/tools/releasetools/test_build_image.py
index 1cebd0c..b24805f 100644
--- a/tools/releasetools/test_build_image.py
+++ b/tools/releasetools/test_build_image.py
@@ -18,12 +18,13 @@
 import os.path
 
 import common
+import test_utils
 from build_image import (
-    BuildImageError, CheckHeadroom, GetFilesystemCharacteristics, SetUpInDirAndFsConfig)
-from test_utils import ReleaseToolsTestCase
+    BuildImageError, CheckHeadroom, GetFilesystemCharacteristics,
+    SetUpInDirAndFsConfig)
 
 
-class BuildImageTest(ReleaseToolsTestCase):
+class BuildImageTest(test_utils.ReleaseToolsTestCase):
 
   # Available: 1000 blocks.
   EXT4FS_OUTPUT = (
@@ -48,6 +49,7 @@
     self.assertRaises(
         BuildImageError, CheckHeadroom, self.EXT4FS_OUTPUT, prop_dict)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_CheckHeadroom_WrongFsType(self):
     prop_dict = {
         'fs_type' : 'f2fs',
@@ -72,6 +74,7 @@
     self.assertRaises(
         AssertionError, CheckHeadroom, self.EXT4FS_OUTPUT, prop_dict)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_CheckHeadroom_WithMke2fsOutput(self):
     """Tests the result parsing from actual call to mke2fs."""
     input_dir = common.MakeTempDir()
@@ -177,13 +180,14 @@
     self.assertIn('fs-config-root\n', fs_config_data)
     self.assertEqual('/', prop_dict['mount_point'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetFilesystemCharacteristics(self):
     input_dir = common.MakeTempDir()
     output_image = common.MakeTempFile(suffix='.img')
     command = ['mkuserimg_mke2fs', input_dir, output_image, 'ext4',
                '/system', '409600', '-j', '0']
     proc = common.Run(command)
-    ext4fs_output, _ = proc.communicate()
+    proc.communicate()
     self.assertEqual(0, proc.returncode)
 
     output_file = common.MakeTempFile(suffix='.img')
diff --git a/tools/releasetools/test_common.py b/tools/releasetools/test_common.py
index 89add40..9b76734 100644
--- a/tools/releasetools/test_common.py
+++ b/tools/releasetools/test_common.py
@@ -315,6 +315,7 @@
     finally:
       os.remove(zip_file_name)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ZipDelete(self):
     zip_file = tempfile.NamedTemporaryFile(delete=False, suffix='.zip')
     output_zip = zipfile.ZipFile(zip_file.name, 'w',
@@ -376,6 +377,7 @@
     common.ZipClose(output_zip)
     return zip_file
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_UnzipTemp(self):
     zip_file = self._test_UnzipTemp_createZipFile()
     unzipped_dir = common.UnzipTemp(zip_file)
@@ -385,6 +387,7 @@
     self.assertTrue(os.path.exists(os.path.join(unzipped_dir, 'Bar4')))
     self.assertTrue(os.path.exists(os.path.join(unzipped_dir, 'Dir5/Baz5')))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_UnzipTemp_withPatterns(self):
     zip_file = self._test_UnzipTemp_createZipFile()
 
@@ -425,6 +428,7 @@
     self.assertFalse(os.path.exists(os.path.join(unzipped_dir, 'Bar4')))
     self.assertFalse(os.path.exists(os.path.join(unzipped_dir, 'Dir5/Baz5')))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_UnzipTemp_withPartiallyMatchingPatterns(self):
     zip_file = self._test_UnzipTemp_createZipFile()
     unzipped_dir = common.UnzipTemp(zip_file, ['Test*', 'Nonexistent*'])
@@ -575,6 +579,7 @@
     wrong_input = os.path.join(self.testdata_dir, 'testkey.pk8')
     self.assertRaises(AssertionError, common.ExtractPublicKey, wrong_input)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ExtractAvbPublicKey(self):
     privkey = os.path.join(self.testdata_dir, 'testkey.key')
     pubkey = os.path.join(self.testdata_dir, 'testkey.pubkey.pem')
@@ -594,18 +599,22 @@
       actual = common.ParseCertificate(cert_fp.read())
     self.assertEqual(expected, actual)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetMinSdkVersion(self):
     test_app = os.path.join(self.testdata_dir, 'TestApp.apk')
     self.assertEqual('24', common.GetMinSdkVersion(test_app))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetMinSdkVersion_invalidInput(self):
     self.assertRaises(
         common.ExternalError, common.GetMinSdkVersion, 'does-not-exist.apk')
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetMinSdkVersionInt(self):
     test_app = os.path.join(self.testdata_dir, 'TestApp.apk')
     self.assertEqual(24, common.GetMinSdkVersionInt(test_app, {}))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetMinSdkVersionInt_invalidInput(self):
     self.assertRaises(
         common.ExternalError, common.GetMinSdkVersionInt, 'does-not-exist.apk',
@@ -617,6 +626,7 @@
   def setUp(self):
     self.testdata_dir = test_utils.get_testdata_dir()
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_emptyBlockMapFile(self):
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
     with zipfile.ZipFile(target_files, 'w') as target_files_zip:
@@ -649,6 +659,7 @@
         AssertionError, common.GetSparseImage, 'unknown', self.testdata_dir,
         None, False)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_missingBlockMapFile(self):
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
     with zipfile.ZipFile(target_files, 'w') as target_files_zip:
@@ -667,6 +678,7 @@
           AssertionError, common.GetSparseImage, 'system', tempdir, input_zip,
           False)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_sharedBlocks_notAllowed(self):
     """Tests the case of having overlapping blocks but disallowed."""
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
@@ -689,6 +701,7 @@
           AssertionError, common.GetSparseImage, 'system', tempdir, input_zip,
           False)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_sharedBlocks_allowed(self):
     """Tests the case for target using BOARD_EXT4_SHARE_DUP_BLOCKS := true."""
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
@@ -731,6 +744,7 @@
     self.assertFalse(sparse_image.file_map['__NONZERO-0'].extra)
     self.assertFalse(sparse_image.file_map['/system/file1'].extra)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_incompleteRanges(self):
     """Tests the case of ext4 images with holes."""
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
@@ -754,6 +768,7 @@
     self.assertFalse(sparse_image.file_map['/system/file1'].extra)
     self.assertTrue(sparse_image.file_map['/system/file2'].extra['incomplete'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_systemRootImage_filenameWithExtraLeadingSlash(self):
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
     with zipfile.ZipFile(target_files, 'w') as target_files_zip:
@@ -781,6 +796,7 @@
     self.assertTrue(
         sparse_image.file_map['/system/app/file3'].extra['incomplete'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_systemRootImage_nonSystemFiles(self):
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
     with zipfile.ZipFile(target_files, 'w') as target_files_zip:
@@ -803,6 +819,7 @@
     self.assertFalse(sparse_image.file_map['//system/file1'].extra)
     self.assertTrue(sparse_image.file_map['//init.rc'].extra['incomplete'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetSparseImage_fileNotFound(self):
     target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
     with zipfile.ZipFile(target_files, 'w') as target_files_zip:
@@ -822,6 +839,7 @@
           AssertionError, common.GetSparseImage, 'system', tempdir, input_zip,
           False)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetAvbChainedPartitionArg(self):
     pubkey = os.path.join(self.testdata_dir, 'testkey.pubkey.pem')
     info_dict = {
@@ -835,6 +853,7 @@
     self.assertEqual('2', args[1])
     self.assertTrue(os.path.exists(args[2]))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetAvbChainedPartitionArg_withPrivateKey(self):
     key = os.path.join(self.testdata_dir, 'testkey.key')
     info_dict = {
@@ -848,6 +867,7 @@
     self.assertEqual('2', args[1])
     self.assertTrue(os.path.exists(args[2]))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetAvbChainedPartitionArg_withSpecifiedKey(self):
     info_dict = {
         'avb_avbtool': 'avbtool',
@@ -862,6 +882,7 @@
     self.assertEqual('2', args[1])
     self.assertTrue(os.path.exists(args[2]))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetAvbChainedPartitionArg_invalidKey(self):
     pubkey = os.path.join(self.testdata_dir, 'testkey_with_passwd.x509.pem')
     info_dict = {
@@ -922,6 +943,7 @@
       self.assertIn('/', loaded_dict['fstab'])
       self.assertIn('/system', loaded_dict['fstab'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_LoadInfoDict_dirInput(self):
     target_files = self._test_LoadInfoDict_createTargetFiles(
         self.INFO_DICT_DEFAULT,
@@ -933,6 +955,7 @@
     self.assertIn('/', loaded_dict['fstab'])
     self.assertIn('/system', loaded_dict['fstab'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_LoadInfoDict_dirInput_legacyRecoveryFstabPath(self):
     target_files = self._test_LoadInfoDict_createTargetFiles(
         self.INFO_DICT_DEFAULT,
@@ -990,6 +1013,7 @@
       self.assertEqual(2, loaded_dict['fstab_version'])
       self.assertIsNone(loaded_dict['fstab'])
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_LoadInfoDict_missingMetaMiscInfoTxt(self):
     target_files = self._test_LoadInfoDict_createTargetFiles(
         self.INFO_DICT_DEFAULT,
@@ -998,6 +1022,7 @@
     with zipfile.ZipFile(target_files, 'r') as target_files_zip:
       self.assertRaises(ValueError, common.LoadInfoDict, target_files_zip)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_LoadInfoDict_repacking(self):
     target_files = self._test_LoadInfoDict_createTargetFiles(
         self.INFO_DICT_DEFAULT,
@@ -1066,6 +1091,7 @@
     validate_target_files.ValidateInstallRecoveryScript(self._tempdir,
                                                         self._info)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_recovery_from_boot(self):
     recovery_image = common.File("recovery.img", self.recovery_data)
     self._out_tmp_sink("recovery.img", recovery_image.data, "IMAGES")
diff --git a/tools/releasetools/test_merge_target_files.py b/tools/releasetools/test_merge_target_files.py
index bb9ce8e..ec452a8 100644
--- a/tools/releasetools/test_merge_target_files.py
+++ b/tools/releasetools/test_merge_target_files.py
@@ -16,7 +16,6 @@
 
 import os.path
 
-import common
 import test_utils
 from merge_target_files import (
     read_config_list, validate_config_lists, default_system_item_list,
diff --git a/tools/releasetools/test_ota_from_target_files.py b/tools/releasetools/test_ota_from_target_files.py
index 466fde1..ee831e3 100644
--- a/tools/releasetools/test_ota_from_target_files.py
+++ b/tools/releasetools/test_ota_from_target_files.py
@@ -425,7 +425,6 @@
     }
 
     common.OPTIONS.search_path = test_utils.get_search_path()
-    self.assertIsNotNone(common.OPTIONS.search_path)
 
   def test_GetPackageMetadata_abOta_full(self):
     target_info_dict = copy.deepcopy(self.TEST_TARGET_INFO_DICT)
@@ -582,6 +581,7 @@
         },
         metadata)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipForSecondaryImages(self):
     input_file = construct_target_files(secondary=True)
     target_file = GetTargetFilesZipForSecondaryImages(input_file)
@@ -600,6 +600,7 @@
     self.assertNotIn('IMAGES/system_other.img', namelist)
     self.assertNotIn('IMAGES/system.map', namelist)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipForSecondaryImages_skipPostinstall(self):
     input_file = construct_target_files(secondary=True)
     target_file = GetTargetFilesZipForSecondaryImages(
@@ -619,6 +620,7 @@
     self.assertNotIn('IMAGES/system.map', namelist)
     self.assertNotIn(POSTINSTALL_CONFIG, namelist)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipForSecondaryImages_withoutRadioImages(self):
     input_file = construct_target_files(secondary=True)
     common.ZipDelete(input_file, 'RADIO/bootloader.img')
@@ -639,12 +641,14 @@
     self.assertNotIn('RADIO/bootloader.img', namelist)
     self.assertNotIn('RADIO/modem.img', namelist)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipWithoutPostinstallConfig(self):
     input_file = construct_target_files()
     target_file = GetTargetFilesZipWithoutPostinstallConfig(input_file)
     with zipfile.ZipFile(target_file) as verify_zip:
       self.assertNotIn(POSTINSTALL_CONFIG, verify_zip.namelist())
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipWithoutPostinstallConfig_missingEntry(self):
     input_file = construct_target_files()
     common.ZipDelete(input_file, POSTINSTALL_CONFIG)
@@ -675,20 +679,25 @@
     FinalizeMetadata(metadata, zip_file, output_file, needed_property_files)
     self.assertIn('ota-test-property-files', metadata)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata(self):
     self._test_FinalizeMetadata()
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata_withNoSigning(self):
     common.OPTIONS.no_signing = True
     self._test_FinalizeMetadata()
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata_largeEntry(self):
     self._test_FinalizeMetadata(large_entry=True)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata_largeEntry_withNoSigning(self):
     common.OPTIONS.no_signing = True
     self._test_FinalizeMetadata(large_entry=True)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata_insufficientSpace(self):
     entries = [
         'required-entry1',
@@ -766,6 +775,7 @@
           expected = entry.replace('.', '-').upper().encode()
         self.assertEqual(expected, input_fp.read(size))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Compute(self):
     entries = (
         'required-entry1',
@@ -805,6 +815,7 @@
     with zipfile.ZipFile(zip_file, 'r') as zip_fp:
       self.assertRaises(KeyError, property_files.Compute, zip_fp)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Finalize(self):
     entries = [
         'required-entry1',
@@ -825,6 +836,7 @@
     entries[2] = 'metadata'
     self._verify_entries(zip_file, tokens, entries)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Finalize_assertReservedLength(self):
     entries = (
         'required-entry1',
@@ -998,6 +1010,7 @@
         ),
         property_files.optional)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetPayloadMetadataOffsetAndSize(self):
     target_file = construct_target_files()
     payload = Payload()
@@ -1071,6 +1084,7 @@
 
     return zip_file
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Compute(self):
     zip_file = self.construct_zip_package_withValidPayload()
     property_files = AbOtaPropertyFiles()
@@ -1084,6 +1098,7 @@
     self._verify_entries(
         zip_file, tokens, ('care_map.txt', 'compatibility.zip'))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Finalize(self):
     zip_file = self.construct_zip_package_withValidPayload(with_metadata=True)
     property_files = AbOtaPropertyFiles()
@@ -1099,6 +1114,7 @@
     self._verify_entries(
         zip_file, tokens, ('care_map.txt', 'compatibility.zip'))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Verify(self):
     zip_file = self.construct_zip_package_withValidPayload(with_metadata=True)
     property_files = AbOtaPropertyFiles()
@@ -1204,6 +1220,7 @@
 
   def test_GetKeySizeInBytes_512Bytes(self):
     signing_key = os.path.join(self.testdata_dir, 'testkey_RSA4096.key')
+    # pylint: disable=protected-access
     key_size = PayloadSigner._GetKeySizeInBytes(signing_key)
     self.assertEqual(512, key_size)
 
@@ -1233,6 +1250,7 @@
     """Uses testdata/payload_signer.sh as the external payload signer."""
     common.OPTIONS.payload_signer = os.path.join(
         self.testdata_dir, 'payload_signer.sh')
+    os.chmod(common.OPTIONS.payload_signer, 0o700)
     common.OPTIONS.payload_signer_args = [
         os.path.join(self.testdata_dir, 'testkey.pk8')]
     payload_signer = PayloadSigner()
@@ -1272,14 +1290,17 @@
     payload.Generate(target_file, source_file)
     return payload
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Generate_full(self):
     payload = self._create_payload_full()
     self.assertTrue(os.path.exists(payload.payload_file))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Generate_incremental(self):
     payload = self._create_payload_incremental()
     self.assertTrue(os.path.exists(payload.payload_file))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Generate_additionalArgs(self):
     target_file = construct_target_files()
     source_file = construct_target_files()
@@ -1290,12 +1311,14 @@
         target_file, additional_args=["--source_image", source_file])
     self.assertTrue(os.path.exists(payload.payload_file))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Generate_invalidInput(self):
     target_file = construct_target_files()
     common.ZipDelete(target_file, 'IMAGES/vendor.img')
     payload = Payload()
     self.assertRaises(common.ExternalError, payload.Generate, target_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Sign_full(self):
     payload = self._create_payload_full()
     payload.Sign(PayloadSigner())
@@ -1309,6 +1332,7 @@
         os.path.join(self.testdata_dir, 'testkey.x509.pem'),
         output_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Sign_incremental(self):
     payload = self._create_payload_incremental()
     payload.Sign(PayloadSigner())
@@ -1322,6 +1346,7 @@
         os.path.join(self.testdata_dir, 'testkey.x509.pem'),
         output_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Sign_withDataWipe(self):
     common.OPTIONS.wipe_user_data = True
     payload = self._create_payload_full()
@@ -1330,6 +1355,7 @@
     with open(payload.payload_properties) as properties_fp:
       self.assertIn("POWERWASH=1", properties_fp.read())
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Sign_secondary(self):
     payload = self._create_payload_full(secondary=True)
     payload.Sign(PayloadSigner())
@@ -1337,6 +1363,7 @@
     with open(payload.payload_properties) as properties_fp:
       self.assertIn("SWITCH_SLOT_ON_REBOOT=0", properties_fp.read())
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_Sign_badSigner(self):
     """Tests that signing failure can be captured."""
     payload = self._create_payload_full()
@@ -1344,6 +1371,7 @@
     payload_signer.signer_args.append('bad-option')
     self.assertRaises(common.ExternalError, payload.Sign, payload_signer)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_WriteToZip(self):
     payload = self._create_payload_full()
     payload.Sign(PayloadSigner())
@@ -1365,6 +1393,7 @@
           continue
         self.assertEqual(zipfile.ZIP_STORED, entry_info.compress_type)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_WriteToZip_unsignedPayload(self):
     """Unsigned payloads should not be allowed to be written to zip."""
     payload = self._create_payload_full()
@@ -1380,6 +1409,7 @@
     with zipfile.ZipFile(output_file, 'w') as output_zip:
       self.assertRaises(AssertionError, payload.WriteToZip, output_zip)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_WriteToZip_secondary(self):
     payload = self._create_payload_full(secondary=True)
     payload.Sign(PayloadSigner())
diff --git a/tools/releasetools/test_utils.py b/tools/releasetools/test_utils.py
old mode 100644
new mode 100755
index edb3d41..1e919f7
--- a/tools/releasetools/test_utils.py
+++ b/tools/releasetools/test_utils.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 #
 # Copyright (C) 2018 The Android Open Source Project
 #
@@ -30,6 +31,18 @@
 # Some test runner doesn't like outputs from stderr.
 logging.basicConfig(stream=sys.stdout)
 
+# Use ANDROID_BUILD_TOP as an indicator to tell if the needed tools (e.g.
+# avbtool, mke2fs) are available while running the tests. Not having the var or
+# having empty string means we can't run the tests that require external tools.
+EXTERNAL_TOOLS_UNAVAILABLE = not os.environ.get("ANDROID_BUILD_TOP")
+
+
+def SkipIfExternalToolsUnavailable():
+  """Decorator function that allows skipping tests per tools availability."""
+  if EXTERNAL_TOOLS_UNAVAILABLE:
+    return unittest.skip('External tools unavailable')
+  return lambda func: func
+
 
 def get_testdata_dir():
   """Returns the testdata dir, in relative to the script dir."""
@@ -40,6 +53,19 @@
 
 def get_search_path():
   """Returns the search path that has 'framework/signapk.jar' under."""
+
+  def signapk_exists(path):
+    signapk_path = os.path.realpath(
+        os.path.join(path, 'framework', 'signapk.jar'))
+    return os.path.exists(signapk_path)
+
+  # Try with ANDROID_BUILD_TOP first.
+  full_path = os.path.realpath(os.path.join(
+      os.environ.get('ANDROID_BUILD_TOP', ''), 'out', 'host', 'linux-x86'))
+  if signapk_exists(full_path):
+    return full_path
+
+  # Otherwise try going with relative pathes.
   current_dir = os.path.dirname(os.path.realpath(__file__))
   for path in (
       # In relative to 'build/make/tools/releasetools' in the Android source.
@@ -47,9 +73,7 @@
       # Or running the script unpacked from otatools.zip.
       ['..']):
     full_path = os.path.realpath(os.path.join(current_dir, *path))
-    signapk_path = os.path.realpath(
-        os.path.join(full_path, 'framework', 'signapk.jar'))
-    if os.path.exists(signapk_path):
+    if signapk_exists(full_path):
       return full_path
   return None
 
@@ -123,3 +147,10 @@
 
   def tearDown(self):
     common.Cleanup()
+
+
+if __name__ == '__main__':
+  testsuite = unittest.TestLoader().discover(
+      os.path.dirname(os.path.realpath(__file__)))
+  # atest needs a verbosity level of >= 2 to correctly parse the result.
+  unittest.TextTestRunner(verbosity=2).run(testsuite)
diff --git a/tools/releasetools/test_validate_target_files.py b/tools/releasetools/test_validate_target_files.py
index 5f619ec..70e3b49 100644
--- a/tools/releasetools/test_validate_target_files.py
+++ b/tools/releasetools/test_validate_target_files.py
@@ -55,6 +55,7 @@
         0, proc.returncode,
         "Failed to sign boot image with boot_signer: {}".format(stdoutdata))
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ValidateVerifiedBootImages_bootImage(self):
     input_tmp = common.MakeTempDir()
     os.mkdir(os.path.join(input_tmp, 'IMAGES'))
@@ -69,6 +70,7 @@
     }
     ValidateVerifiedBootImages(input_tmp, info_dict, options)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ValidateVerifiedBootImages_bootImage_wrongKey(self):
     input_tmp = common.MakeTempDir()
     os.mkdir(os.path.join(input_tmp, 'IMAGES'))
@@ -85,6 +87,7 @@
         AssertionError, ValidateVerifiedBootImages, input_tmp, info_dict,
         options)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ValidateVerifiedBootImages_bootImage_corrupted(self):
     input_tmp = common.MakeTempDir()
     os.mkdir(os.path.join(input_tmp, 'IMAGES'))
@@ -139,6 +142,7 @@
     # Append the verity metadata.
     verity_image_builder.Build(output_file)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ValidateVerifiedBootImages_systemImage(self):
     input_tmp = common.MakeTempDir()
     os.mkdir(os.path.join(input_tmp, 'IMAGES'))
@@ -162,6 +166,7 @@
     }
     ValidateVerifiedBootImages(input_tmp, info_dict, options)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_ValidateFileConsistency_incompleteRange(self):
     input_tmp = common.MakeTempDir()
     os.mkdir(os.path.join(input_tmp, 'IMAGES'))
diff --git a/tools/releasetools/test_verity_utils.py b/tools/releasetools/test_verity_utils.py
index e0607c8..1cc539f 100644
--- a/tools/releasetools/test_verity_utils.py
+++ b/tools/releasetools/test_verity_utils.py
@@ -24,7 +24,8 @@
 import common
 import sparse_img
 from rangelib import RangeSet
-from test_utils import get_testdata_dir, ReleaseToolsTestCase
+from test_utils import (
+    get_testdata_dir, ReleaseToolsTestCase, SkipIfExternalToolsUnavailable)
 from verity_utils import (
     CreateHashtreeInfoGenerator, CreateVerityImageBuilder, HashtreeInfo,
     VerifiedBootVersion1HashtreeInfoGenerator)
@@ -89,6 +90,7 @@
 
     return output_file
 
+  @SkipIfExternalToolsUnavailable()
   def test_CreateHashtreeInfoGenerator(self):
     image_file = sparse_img.SparseImage(self._generate_image())
 
@@ -99,6 +101,7 @@
     self.assertEqual(self.partition_size, generator.partition_size)
     self.assertTrue(generator.fec_supported)
 
+  @SkipIfExternalToolsUnavailable()
   def test_DecomposeSparseImage(self):
     image_file = sparse_img.SparseImage(self._generate_image())
 
@@ -109,6 +112,7 @@
     self.assertEqual(12288, generator.hashtree_size)
     self.assertEqual(32768, generator.metadata_size)
 
+  @SkipIfExternalToolsUnavailable()
   def test_ParseHashtreeMetadata(self):
     image_file = sparse_img.SparseImage(self._generate_image())
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
@@ -123,6 +127,7 @@
     self.assertEqual(self.fixed_salt, generator.hashtree_info.salt)
     self.assertEqual(self.expected_root_hash, generator.hashtree_info.root_hash)
 
+  @SkipIfExternalToolsUnavailable()
   def test_ValidateHashtree_smoke(self):
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
@@ -138,6 +143,7 @@
 
     self.assertTrue(generator.ValidateHashtree())
 
+  @SkipIfExternalToolsUnavailable()
   def test_ValidateHashtree_failure(self):
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
@@ -153,6 +159,7 @@
 
     self.assertFalse(generator.ValidateHashtree())
 
+  @SkipIfExternalToolsUnavailable()
   def test_Generate(self):
     image_file = sparse_img.SparseImage(self._generate_image())
     generator = CreateHashtreeInfoGenerator('system', 4096, self.prop_dict)
@@ -193,6 +200,7 @@
     del prop_dict['verity_block_device']
     self.assertIsNone(CreateVerityImageBuilder(prop_dict))
 
+  @SkipIfExternalToolsUnavailable()
   def test_CalculateMaxImageSize(self):
     verity_image_builder = CreateVerityImageBuilder(self.DEFAULT_PROP_DICT)
     size = verity_image_builder.CalculateMaxImageSize()
@@ -221,11 +229,13 @@
     cmd = ['verity_verifier', image, '-mincrypt', verify_key]
     common.RunAndCheckOutput(cmd)
 
+  @SkipIfExternalToolsUnavailable()
   def test_Build(self):
     self._BuildAndVerify(
         self.DEFAULT_PROP_DICT,
         os.path.join(get_testdata_dir(), 'testkey_mincrypt'))
 
+  @SkipIfExternalToolsUnavailable()
   def test_Build_SanityCheck(self):
     # A sanity check for the test itself: the image shouldn't be verifiable
     # with wrong key.
@@ -235,6 +245,7 @@
         self.DEFAULT_PROP_DICT,
         os.path.join(get_testdata_dir(), 'verity_mincrypt'))
 
+  @SkipIfExternalToolsUnavailable()
   def test_Build_FecDisabled(self):
     prop_dict = copy.deepcopy(self.DEFAULT_PROP_DICT)
     del prop_dict['verity_fec']
@@ -242,6 +253,7 @@
         prop_dict,
         os.path.join(get_testdata_dir(), 'testkey_mincrypt'))
 
+  @SkipIfExternalToolsUnavailable()
   def test_Build_SquashFs(self):
     verity_image_builder = CreateVerityImageBuilder(self.DEFAULT_PROP_DICT)
     verity_image_builder.CalculateMaxImageSize()
@@ -282,6 +294,7 @@
     verity_image_builder = CreateVerityImageBuilder(prop_dict)
     self.assertIsNone(verity_image_builder)
 
+  @SkipIfExternalToolsUnavailable()
   def test_Build(self):
     prop_dict = copy.deepcopy(self.DEFAULT_PROP_DICT)
     verity_image_builder = CreateVerityImageBuilder(prop_dict)