store images in target-files

Store sparse images in the target-files, and use those (when they're
available) for building block OTAs.

- New script add_img_to_target_files is added to make the images and
  add them to the IMAGES/ subdir in the target-files.  It gets run
  from the Makefile when building a target-files.

- img_from_target_files becomes mostly vestigial: it creates the
  img.zip by just copying the images out of the target-files.  (It
  still knows how to build images for use on older target-files.)

- ota_from_target_files uses images from the target-files in
  preference to rebuilding images from the source files.

- sign_apk_target_files builds images and includes them in its output
  target files (even if the input target-files didn't have them).

Bug: 16488065
Change-Id: I444e0d722d636978209467ffc01750a585c6db75
diff --git a/core/Makefile b/core/Makefile
index 36d53e1..c556ed7 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1415,6 +1415,7 @@
 	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="BOOT/RAMDISK/" } /^BOOT\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config -C -S $(SELINUX_FC) > $(zip_root)/META/boot_filesystem_config.txt
 	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="RECOVERY/RAMDISK/" } /^RECOVERY\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config -C -S $(SELINUX_FC) > $(zip_root)/META/recovery_filesystem_config.txt
 	$(hide) (cd $(zip_root) && zip -q ../$(notdir $@) META/*filesystem_config.txt)
+	$(hide) ./build/tools/releasetools/add_img_to_target_files $@
 
 .PHONY: target-files-package
 target-files-package: $(BUILT_TARGET_FILES_PACKAGE)
diff --git a/tools/releasetools/add_img_to_target_files b/tools/releasetools/add_img_to_target_files
new file mode 120000
index 0000000..04323bd
--- /dev/null
+++ b/tools/releasetools/add_img_to_target_files
@@ -0,0 +1 @@
+add_img_to_target_files.py
\ No newline at end of file
diff --git a/tools/releasetools/add_img_to_target_files.py b/tools/releasetools/add_img_to_target_files.py
new file mode 100755
index 0000000..7be1929
--- /dev/null
+++ b/tools/releasetools/add_img_to_target_files.py
@@ -0,0 +1,284 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2014 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 target-files zipfile that does not contain images (ie, does
+not have an IMAGES/ top-level subdirectory), produce the images and
+add them to the zipfile.
+
+Usage:  add_img_to_target_files target_files
+"""
+
+import sys
+
+if sys.hexversion < 0x02070000:
+  print >> sys.stderr, "Python 2.7 or newer is required."
+  sys.exit(1)
+
+import errno
+import os
+import re
+import shutil
+import subprocess
+import tempfile
+import zipfile
+
+# missing in Python 2.4 and before
+if not hasattr(os, "SEEK_SET"):
+  os.SEEK_SET = 0
+
+import build_image
+import common
+
+OPTIONS = common.OPTIONS
+
+
+def AddSystem(output_zip, sparse=True, prefix="IMAGES/"):
+  """Turn the contents of SYSTEM into a system image and store it in
+  output_zip."""
+  data = BuildSystem(OPTIONS.input_tmp, OPTIONS.info_dict, sparse=sparse)
+  common.ZipWriteStr(output_zip, prefix + "system.img", data)
+
+def BuildSystem(input_dir, info_dict, sparse=True, map_file=None):
+  return CreateImage(input_dir, info_dict, "system",
+                     sparse=sparse, map_file=map_file)
+
+def AddVendor(output_zip, sparse=True, prefix="IMAGES/"):
+  data = BuildVendor(OPTIONS.input_tmp, OPTIONS.info_dict, sparse=sparse)
+  common.ZipWriteStr(output_zip, prefix + "vendor.img", data)
+
+def BuildVendor(input_dir, info_dict, sparse=True, map_file=None):
+  return CreateImage(input_dir, info_dict, "vendor",
+                     sparse=sparse, map_file=map_file)
+
+
+def CreateImage(input_dir, info_dict, what, sparse=True, map_file=None):
+  print "creating " + what + ".img..."
+
+  img = tempfile.NamedTemporaryFile()
+
+  # The name of the directory it is making an image out of matters to
+  # mkyaffs2image.  It wants "system" but we have a directory named
+  # "SYSTEM", so create a symlink.
+  try:
+    os.symlink(os.path.join(input_dir, what.upper()),
+               os.path.join(input_dir, what))
+  except OSError, e:
+      # bogus error on my mac version?
+      #   File "./build/tools/releasetools/img_from_target_files", line 86, in AddSystem
+      #     os.path.join(OPTIONS.input_tmp, "system"))
+      # OSError: [Errno 17] File exists
+    if (e.errno == errno.EEXIST):
+      pass
+
+  image_props = build_image.ImagePropFromGlobalDict(info_dict, what)
+  fstab = info_dict["fstab"]
+  if fstab:
+    image_props["fs_type" ] = fstab["/" + what].fs_type
+
+  if what == "system":
+    fs_config_prefix = ""
+  else:
+    fs_config_prefix = what + "_"
+
+  fs_config = os.path.join(
+      input_dir, "META/" + fs_config_prefix + "filesystem_config.txt")
+  if not os.path.exists(fs_config): fs_config = None
+
+  fc_config = os.path.join(input_dir, "BOOT/RAMDISK/file_contexts")
+  if not os.path.exists(fc_config): fc_config = None
+
+  succ = build_image.BuildImage(os.path.join(input_dir, what),
+                                image_props, img.name,
+                                fs_config=fs_config,
+                                fc_config=fc_config)
+  assert succ, "build " + what + ".img image failed"
+
+  mapdata = None
+
+  if sparse:
+    data = open(img.name).read()
+    img.close()
+  else:
+    success, name = build_image.UnsparseImage(img.name, replace=False)
+    if not success:
+      assert False, "unsparsing " + what + ".img failed"
+
+    if map_file:
+      mmap = tempfile.NamedTemporaryFile()
+      mimg = tempfile.NamedTemporaryFile(delete=False)
+      success = build_image.MappedUnsparseImage(
+          img.name, name, mmap.name, mimg.name)
+      if not success:
+        assert False, "creating sparse map failed"
+      os.unlink(name)
+      name = mimg.name
+
+      with open(mmap.name) as f:
+        mapdata = f.read()
+
+    try:
+      with open(name) as f:
+        data = f.read()
+    finally:
+      os.unlink(name)
+
+  if mapdata is None:
+    return data
+  else:
+    return mapdata, data
+
+
+def AddUserdata(output_zip, prefix="IMAGES/"):
+  """Create an empty userdata image and store it in output_zip."""
+
+  image_props = build_image.ImagePropFromGlobalDict(OPTIONS.info_dict,
+                                                    "data")
+  # We only allow yaffs to have a 0/missing partition_size.
+  # Extfs, f2fs must have a size. Skip userdata.img if no size.
+  if (not image_props.get("fs_type", "").startswith("yaffs") and
+      not image_props.get("partition_size")):
+    return
+
+  print "creating userdata.img..."
+
+  # The name of the directory it is making an image out of matters to
+  # mkyaffs2image.  So we create a temp dir, and within it we create an
+  # empty dir named "data", and build the image from that.
+  temp_dir = tempfile.mkdtemp()
+  user_dir = os.path.join(temp_dir, "data")
+  os.mkdir(user_dir)
+  img = tempfile.NamedTemporaryFile()
+
+  fstab = OPTIONS.info_dict["fstab"]
+  if fstab:
+    image_props["fs_type" ] = fstab["/data"].fs_type
+  succ = build_image.BuildImage(user_dir, image_props, img.name)
+  assert succ, "build userdata.img image failed"
+
+  common.CheckSize(img.name, "userdata.img", OPTIONS.info_dict)
+  output_zip.write(img.name, prefix + "userdata.img")
+  img.close()
+  os.rmdir(user_dir)
+  os.rmdir(temp_dir)
+
+
+def AddCache(output_zip, prefix="IMAGES/"):
+  """Create an empty cache image and store it in output_zip."""
+
+  image_props = build_image.ImagePropFromGlobalDict(OPTIONS.info_dict,
+                                                    "cache")
+  # The build system has to explicitly request for cache.img.
+  if "fs_type" not in image_props:
+    return
+
+  print "creating cache.img..."
+
+  # The name of the directory it is making an image out of matters to
+  # mkyaffs2image.  So we create a temp dir, and within it we create an
+  # empty dir named "cache", and build the image from that.
+  temp_dir = tempfile.mkdtemp()
+  user_dir = os.path.join(temp_dir, "cache")
+  os.mkdir(user_dir)
+  img = tempfile.NamedTemporaryFile()
+
+  fstab = OPTIONS.info_dict["fstab"]
+  if fstab:
+    image_props["fs_type" ] = fstab["/cache"].fs_type
+  succ = build_image.BuildImage(user_dir, image_props, img.name)
+  assert succ, "build cache.img image failed"
+
+  common.CheckSize(img.name, "cache.img", OPTIONS.info_dict)
+  output_zip.write(img.name, prefix + "cache.img")
+  img.close()
+  os.rmdir(user_dir)
+  os.rmdir(temp_dir)
+
+
+def AddImagesToTargetFiles(filename):
+  OPTIONS.input_tmp, input_zip = common.UnzipTemp(filename)
+  try:
+
+    for n in input_zip.namelist():
+      if n.startswith("IMAGES/"):
+        print "target_files appears to already contain images."
+        sys.exit(1)
+
+    try:
+      input_zip.getinfo("VENDOR/")
+      has_vendor = True
+    except KeyError:
+      has_vendor = False
+
+    OPTIONS.info_dict = common.LoadInfoDict(input_zip)
+    if "selinux_fc" in OPTIONS.info_dict:
+      OPTIONS.info_dict["selinux_fc"] = os.path.join(
+          OPTIONS.input_tmp, "BOOT", "RAMDISK", "file_contexts")
+
+    input_zip.close()
+    output_zip = zipfile.ZipFile(filename, "a",
+                                 compression=zipfile.ZIP_DEFLATED)
+
+    def banner(s):
+      print "\n\n++++ " + s + " ++++\n\n"
+
+    banner("boot")
+    boot_image = common.GetBootableImage(
+        "IMAGES/boot.img", "boot.img", OPTIONS.input_tmp, "BOOT")
+    if boot_image:
+      boot_image.AddToZip(output_zip)
+
+    banner("recovery")
+    recovery_image = common.GetBootableImage(
+        "IMAGES/recovery.img", "recovery.img", OPTIONS.input_tmp, "RECOVERY")
+    if recovery_image:
+      recovery_image.AddToZip(output_zip)
+
+    banner("system")
+    AddSystem(output_zip)
+    if has_vendor:
+      banner("vendor")
+      AddVendor(output_zip)
+    banner("userdata")
+    AddUserdata(output_zip)
+    banner("cache")
+    AddCache(output_zip)
+
+    output_zip.close()
+
+  finally:
+    shutil.rmtree(OPTIONS.input_tmp)
+
+
+def main(argv):
+  args = common.ParseOptions(argv, __doc__)
+
+  if len(args) != 1:
+    common.Usage(__doc__)
+    sys.exit(1)
+
+  AddImagesToTargetFiles(args[0])
+  print "done."
+
+if __name__ == '__main__':
+  try:
+    common.CloseInheritedPipes()
+    main(sys.argv[1:])
+  except common.ExternalError, e:
+    print
+    print "   ERROR: %s" % (e,)
+    print
+    sys.exit(1)
diff --git a/tools/releasetools/img_from_target_files.py b/tools/releasetools/img_from_target_files.py
index 9aab41c..6463047 100755
--- a/tools/releasetools/img_from_target_files.py
+++ b/tools/releasetools/img_from_target_files.py
@@ -20,9 +20,6 @@
 
 Usage:  img_from_target_files [flags] input_target_files output_image_zip
 
-  -b  (--board_config)  <file>
-      Deprecated.
-
   -z  (--bootable_zip)
       Include only the bootable images (eg 'boot' and 'recovery') in
       the output.
@@ -47,174 +44,11 @@
 if not hasattr(os, "SEEK_SET"):
   os.SEEK_SET = 0
 
-import build_image
 import common
 
 OPTIONS = common.OPTIONS
 
 
-def AddSystem(output_zip, sparse=True):
-  """Turn the contents of SYSTEM into a system image and store it in
-  output_zip."""
-  data = BuildSystem(OPTIONS.input_tmp, OPTIONS.info_dict, sparse=sparse)
-  common.ZipWriteStr(output_zip, "system.img", data)
-
-def BuildSystem(input_dir, info_dict, sparse=True, map_file=None):
-  return CreateImage(input_dir, info_dict, "system",
-                     sparse=sparse, map_file=map_file)
-
-def AddVendor(output_zip, sparse=True):
-  data = BuildVendor(OPTIONS.input_tmp, OPTIONS.info_dict, sparse=sparse)
-  common.ZipWriteStr(output_zip, "vendor.img", data)
-
-def BuildVendor(input_dir, info_dict, sparse=True, map_file=None):
-  return CreateImage(input_dir, info_dict, "vendor",
-                     sparse=sparse, map_file=map_file)
-
-
-def CreateImage(input_dir, info_dict, what, sparse=True, map_file=None):
-  print "creating " + what + ".img..."
-
-  img = tempfile.NamedTemporaryFile()
-
-  # The name of the directory it is making an image out of matters to
-  # mkyaffs2image.  It wants "system" but we have a directory named
-  # "SYSTEM", so create a symlink.
-  try:
-    os.symlink(os.path.join(input_dir, what.upper()),
-               os.path.join(input_dir, what))
-  except OSError, e:
-      # bogus error on my mac version?
-      #   File "./build/tools/releasetools/img_from_target_files", line 86, in AddSystem
-      #     os.path.join(OPTIONS.input_tmp, "system"))
-      # OSError: [Errno 17] File exists
-    if (e.errno == errno.EEXIST):
-      pass
-
-  image_props = build_image.ImagePropFromGlobalDict(info_dict, what)
-  fstab = info_dict["fstab"]
-  if fstab:
-    image_props["fs_type" ] = fstab["/" + what].fs_type
-
-  if what == "system":
-    fs_config_prefix = ""
-  else:
-    fs_config_prefix = what + "_"
-
-  fs_config = os.path.join(
-      input_dir, "META/" + fs_config_prefix + "filesystem_config.txt")
-  if not os.path.exists(fs_config): fs_config = None
-
-  fc_config = os.path.join(input_dir, "BOOT/RAMDISK/file_contexts")
-  if not os.path.exists(fc_config): fc_config = None
-
-  succ = build_image.BuildImage(os.path.join(input_dir, what),
-                                image_props, img.name,
-                                fs_config=fs_config,
-                                fc_config=fc_config)
-  assert succ, "build " + what + ".img image failed"
-
-  mapdata = None
-
-  if sparse:
-    data = open(img.name).read()
-    img.close()
-  else:
-    success, name = build_image.UnsparseImage(img.name, replace=False)
-    if not success:
-      assert False, "unsparsing " + what + ".img failed"
-
-    if map_file:
-      mmap = tempfile.NamedTemporaryFile()
-      mimg = tempfile.NamedTemporaryFile(delete=False)
-      success = build_image.MappedUnsparseImage(
-          img.name, name, mmap.name, mimg.name)
-      if not success:
-        assert False, "creating sparse map failed"
-      os.unlink(name)
-      name = mimg.name
-
-      with open(mmap.name) as f:
-        mapdata = f.read()
-
-    try:
-      with open(name) as f:
-        data = f.read()
-    finally:
-      os.unlink(name)
-
-  if mapdata is None:
-    return data
-  else:
-    return mapdata, data
-
-
-def AddUserdata(output_zip):
-  """Create an empty userdata image and store it in output_zip."""
-
-  image_props = build_image.ImagePropFromGlobalDict(OPTIONS.info_dict,
-                                                    "data")
-  # We only allow yaffs to have a 0/missing partition_size.
-  # Extfs, f2fs must have a size. Skip userdata.img if no size.
-  if (not image_props.get("fs_type", "").startswith("yaffs") and
-      not image_props.get("partition_size")):
-    return
-
-  print "creating userdata.img..."
-
-  # The name of the directory it is making an image out of matters to
-  # mkyaffs2image.  So we create a temp dir, and within it we create an
-  # empty dir named "data", and build the image from that.
-  temp_dir = tempfile.mkdtemp()
-  user_dir = os.path.join(temp_dir, "data")
-  os.mkdir(user_dir)
-  img = tempfile.NamedTemporaryFile()
-
-  fstab = OPTIONS.info_dict["fstab"]
-  if fstab:
-    image_props["fs_type" ] = fstab["/data"].fs_type
-  succ = build_image.BuildImage(user_dir, image_props, img.name)
-  assert succ, "build userdata.img image failed"
-
-  common.CheckSize(img.name, "userdata.img", OPTIONS.info_dict)
-  output_zip.write(img.name, "userdata.img")
-  img.close()
-  os.rmdir(user_dir)
-  os.rmdir(temp_dir)
-
-
-def AddCache(output_zip):
-  """Create an empty cache image and store it in output_zip."""
-
-  image_props = build_image.ImagePropFromGlobalDict(OPTIONS.info_dict,
-                                                    "cache")
-  # The build system has to explicitly request for cache.img.
-  if "fs_type" not in image_props:
-    return
-
-  print "creating cache.img..."
-
-  # The name of the directory it is making an image out of matters to
-  # mkyaffs2image.  So we create a temp dir, and within it we create an
-  # empty dir named "cache", and build the image from that.
-  temp_dir = tempfile.mkdtemp()
-  user_dir = os.path.join(temp_dir, "cache")
-  os.mkdir(user_dir)
-  img = tempfile.NamedTemporaryFile()
-
-  fstab = OPTIONS.info_dict["fstab"]
-  if fstab:
-    image_props["fs_type" ] = fstab["/cache"].fs_type
-  succ = build_image.BuildImage(user_dir, image_props, img.name)
-  assert succ, "build cache.img image failed"
-
-  common.CheckSize(img.name, "cache.img", OPTIONS.info_dict)
-  output_zip.write(img.name, "cache.img")
-  img.close()
-  os.rmdir(user_dir)
-  os.rmdir(temp_dir)
-
-
 def CopyInfo(output_zip):
   """Copy the android-info.txt file from the input to the output."""
   output_zip.write(os.path.join(OPTIONS.input_tmp, "OTA", "android-info.txt"),
@@ -225,8 +59,6 @@
   bootable_only = [False]
 
   def option_handler(o, a):
-    if o in ("-b", "--board_config"):
-      pass       # deprecated
     if o in ("-z", "--bootable_zip"):
       bootable_only[0] = True
     else:
@@ -234,9 +66,8 @@
     return True
 
   args = common.ParseOptions(argv, __doc__,
-                             extra_opts="b:z",
-                             extra_long_opts=["board_config=",
-                                              "bootable_zip"],
+                             extra_opts="z",
+                             extra_long_opts=["bootable_zip"],
                              extra_option_handler=option_handler)
 
   bootable_only = bootable_only[0]
@@ -246,48 +77,69 @@
     sys.exit(1)
 
   OPTIONS.input_tmp, input_zip = common.UnzipTemp(args[0])
-  OPTIONS.info_dict = common.LoadInfoDict(input_zip)
-
-  # If this image was originally labelled with SELinux contexts, make sure we
-  # also apply the labels in our new image. During building, the "file_contexts"
-  # is in the out/ directory tree, but for repacking from target-files.zip it's
-  # in the root directory of the ramdisk.
-  if "selinux_fc" in OPTIONS.info_dict:
-    OPTIONS.info_dict["selinux_fc"] = os.path.join(OPTIONS.input_tmp, "BOOT", "RAMDISK",
-        "file_contexts")
-
   output_zip = zipfile.ZipFile(args[1], "w", compression=zipfile.ZIP_DEFLATED)
+  CopyInfo(output_zip)
 
-  boot_image = common.GetBootableImage(
-      "boot.img", "boot.img", OPTIONS.input_tmp, "BOOT")
-  if boot_image:
-      boot_image.AddToZip(output_zip)
-  recovery_image = common.GetBootableImage(
-      "recovery.img", "recovery.img", OPTIONS.input_tmp, "RECOVERY")
-  if recovery_image:
-    recovery_image.AddToZip(output_zip)
+  try:
+    done = False
+    images_path = os.path.join(OPTIONS.input_tmp, "IMAGES")
+    if os.path.exists(images_path):
+      # If this is a new target-files, it already contains the images,
+      # and all we have to do is copy them to the output zip.
+      images = os.listdir(images_path)
+      if images:
+        for i in images:
+          if bootable_only and i not in ("boot.img", "recovery.img"): continue
+          with open(os.path.join(images_path, i), "r") as f:
+            common.ZipWriteStr(output_zip, i, f.read())
+        done = True
 
-  def banner(s):
-    print "\n\n++++ " + s + " ++++\n\n"
+    if not done:
+      # We have an old target-files that doesn't already contain the
+      # images, so build them.
+      import add_img_to_target_files
 
-  if not bootable_only:
-    banner("AddSystem")
-    AddSystem(output_zip)
-    try:
-      input_zip.getinfo("VENDOR/")
-      banner("AddVendor")
-      AddVendor(output_zip)
-    except KeyError:
-      pass   # no vendor partition for this device
-    banner("AddUserdata")
-    AddUserdata(output_zip)
-    banner("AddCache")
-    AddCache(output_zip)
-    CopyInfo(output_zip)
+      OPTIONS.info_dict = common.LoadInfoDict(input_zip)
 
-  print "cleaning up..."
-  output_zip.close()
-  shutil.rmtree(OPTIONS.input_tmp)
+      # If this image was originally labelled with SELinux contexts,
+      # make sure we also apply the labels in our new image. During
+      # building, the "file_contexts" is in the out/ directory tree,
+      # but for repacking from target-files.zip it's in the root
+      # directory of the ramdisk.
+      if "selinux_fc" in OPTIONS.info_dict:
+        OPTIONS.info_dict["selinux_fc"] = os.path.join(
+            OPTIONS.input_tmp, "BOOT", "RAMDISK", "file_contexts")
+
+      boot_image = common.GetBootableImage(
+          "boot.img", "boot.img", OPTIONS.input_tmp, "BOOT")
+      if boot_image:
+          boot_image.AddToZip(output_zip)
+      recovery_image = common.GetBootableImage(
+          "recovery.img", "recovery.img", OPTIONS.input_tmp, "RECOVERY")
+      if recovery_image:
+        recovery_image.AddToZip(output_zip)
+
+      def banner(s):
+        print "\n\n++++ " + s + " ++++\n\n"
+
+      if not bootable_only:
+        banner("AddSystem")
+        add_img_to_target_files.AddSystem(output_zip, prefix="")
+        try:
+          input_zip.getinfo("VENDOR/")
+          banner("AddVendor")
+          add_img_to_target_files.AddVendor(output_zip, prefix="")
+        except KeyError:
+          pass   # no vendor partition for this device
+        banner("AddUserdata")
+        add_img_to_target_files.AddUserdata(output_zip, prefix="")
+        banner("AddCache")
+        add_img_to_target_files.AddCache(output_zip, prefix="")
+
+  finally:
+    print "cleaning up..."
+    output_zip.close()
+    shutil.rmtree(OPTIONS.input_tmp)
 
   print "done."
 
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 5f2354c..54d4884 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -98,7 +98,6 @@
   from sha import sha as sha1
 
 import common
-import img_from_target_files
 import edify_generator
 import build_image
 
@@ -418,6 +417,63 @@
     GetOemProperty("ro.product.device", oem_props, oem_dict, info_dict),
     GetBuildProp("ro.build.thumbprint", info_dict))
 
+def GetImage(which, tmpdir, info_dict):
+  # Return (mapdata, data) for the given image.  which should be
+  # "system" or "vendor".
+
+  assert which in ("system", "vendor")
+
+  path = os.path.join(tmpdir, "IMAGES", which + ".img")
+  if os.path.exists(path):
+    print "using %s.img from target-files" % (which,)
+
+    # This is a 'new' target-files, which already has the image in it.
+    # The image is a sparse image, though, so we need to unsparse it
+    # and extract the map data.
+
+    success, name = build_image.UnsparseImage(path, replace=False)
+    if not success:
+      assert False, "unsparsing " + which + ".img failed"
+
+    mmap = tempfile.NamedTemporaryFile()
+    mimg = tempfile.NamedTemporaryFile(delete=False)
+    success = build_image.MappedUnsparseImage(
+        path, name, mmap.name, mimg.name)
+    if not success:
+      assert False, "creating sparse map failed"
+    os.unlink(name)
+    name = mimg.name
+
+    with open(mmap.name) as f:
+      mapdata = f.read()
+
+    try:
+      with open(name) as f:
+        data = f.read()
+    finally:
+      os.unlink(name)
+
+    print "unsparsed data sha1 is " + sha1(data).hexdigest()
+    return mapdata, data
+
+  else:
+    print "building %s.img from target-files" % (which,)
+
+    # This is an 'old' target-files, which does not contain images
+    # already built.  Build them.
+
+    import add_img_to_target_files
+    if which == "system":
+      mapdata, data = add_img_to_target_files.BuildSystem(
+          tmpdir, info_dict, sparse=False, map_file=True)
+    elif which == "vendor":
+      mapdata, data = add_img_to_target_files.BuildVendor(
+          tmpdir, info_dict, sparse=False, map_file=True)
+
+    print "built data sha1 is " + sha1(data).hexdigest()
+    return mapdata, data
+
+
 def WriteFullOTAPackage(input_zip, output_zip):
   # TODO: how to determine this?  We don't know what version it will
   # be installed on top of.  For now, we expect the API just won't
@@ -514,9 +570,7 @@
   system_items = ItemSet("system", "META/filesystem_config.txt")
   script.ShowProgress(system_progress, 0)
   if block_based:
-    mapdata, data = img_from_target_files.BuildSystem(
-        OPTIONS.input_tmp, OPTIONS.info_dict,
-        sparse=False, map_file=True)
+    mapdata, data = GetImage("system", OPTIONS.input_tmp, OPTIONS.info_dict)
 
     common.ZipWriteStr(output_zip, "system.map", mapdata)
     common.ZipWriteStr(output_zip, "system.muimg", data)
@@ -551,9 +605,7 @@
     script.ShowProgress(0.1, 0)
 
     if block_based:
-      mapdata, data = img_from_target_files.BuildVendor(
-          OPTIONS.input_tmp, OPTIONS.info_dict,
-          sparse=False, map_file=True)
+      mapdata, data = GetImage("vendor", OPTIONS.input_tmp, OPTIONS.info_dict)
 
       common.ZipWriteStr(output_zip, "vendor.map", mapdata)
       common.ZipWriteStr(output_zip, "vendor.muimg", data)
@@ -647,14 +699,14 @@
     dirs.pop()
 
 class BlockDifference:
-  def __init__(self, partition, builder, output_zip):
+  def __init__(self, partition, output_zip):
     with tempfile.NamedTemporaryFile() as src_file:
       with tempfile.NamedTemporaryFile() as tgt_file:
         print "building source " + partition + " image..."
         src_file = tempfile.NamedTemporaryFile()
-        src_mapdata, src_data = builder(OPTIONS.source_tmp,
-                                        OPTIONS.source_info_dict,
-                                        sparse=False, map_file=True)
+        src_mapdata, src_data = GetImage(partition,
+                                         OPTIONS.source_tmp,
+                                         OPTIONS.source_info_dict)
 
         self.src_sha1 = sha1(src_data).hexdigest()
         print "source " + partition + " sha1:", self.src_sha1
@@ -662,9 +714,9 @@
 
         print "building target " + partition + " image..."
         tgt_file = tempfile.NamedTemporaryFile()
-        tgt_mapdata, tgt_data = builder(OPTIONS.target_tmp,
-                                        OPTIONS.target_info_dict,
-                                        sparse=False, map_file=True)
+        tgt_mapdata, tgt_data = GetImage(partition,
+                                         OPTIONS.target_tmp,
+                                         OPTIONS.target_info_dict)
         self.tgt_sha1 = sha1(tgt_data).hexdigest()
         print "target " + partition + " sha1:", self.tgt_sha1
         tgt_len = len(tgt_data)
@@ -731,13 +783,11 @@
       "/tmp/recovery.img", "recovery.img", OPTIONS.target_tmp, "RECOVERY")
   updating_recovery = (source_recovery.data != target_recovery.data)
 
-  system_diff = BlockDifference("system", img_from_target_files.BuildSystem,
-                                output_zip)
+  system_diff = BlockDifference("system", output_zip)
   if HasVendorPartition(target_zip):
     if not HasVendorPartition(source_zip):
       raise RuntimeError("can't generate incremental that adds /vendor")
-    vendor_diff = BlockDifference("vendor", img_from_target_files.BuildVendor,
-                                  output_zip)
+    vendor_diff = BlockDifference("vendor", output_zip)
 
   oem_props = OPTIONS.target_info_dict.get("oem_fingerprint_properties")
   oem_dict = None
diff --git a/tools/releasetools/sign_target_files_apks b/tools/releasetools/sign_target_files_apks
index 0ecb906..cba0668 100755
--- a/tools/releasetools/sign_target_files_apks
+++ b/tools/releasetools/sign_target_files_apks
@@ -82,6 +82,7 @@
 import tempfile
 import zipfile
 
+import add_img_to_target_files
 import common
 
 OPTIONS = common.OPTIONS
@@ -166,6 +167,8 @@
           f.write(data)
 
   for info in input_tf_zip.infolist():
+    if info.filename.startswith("IMAGES/"): continue
+
     data = input_tf_zip.read(info.filename)
     out_info = copy.copy(info)
 
@@ -448,6 +451,8 @@
   input_zip.close()
   output_zip.close()
 
+  add_img_to_target_files.AddImagesToTargetFiles(args[1])
+
   print "done."