Build cache.img on demand

Bug: 5153694
To build cache.img, set BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE (required,
ext4 only for now), BOARD_CACHEIMAGE_PARTITION_SIZE (optional) in
BoardConfig.mk.

Change-Id: I1d8b91646aa1dba88285e008ad3335768bcbddd2

1 files changed, 33 insertions, 0 deletions

diff --git a/tools/releasetools/img_from_target_files b/tools/releasetools/img_from_target_files
index 4388f69..002e6e6 100755
--- a/tools/releasetools/img_from_target_files
+++ b/tools/releasetools/img_from_target_files
@@ -80,6 +80,38 @@ def AddUserdata(output_zip):
   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 AddSystem(output_zip):
   """Turn the contents of SYSTEM into a system image and store it in
   output_zip."""
@@ -163,6 +195,7 @@ def main(argv):
   if not bootable_only:
     AddSystem(output_zip)
     AddUserdata(output_zip)
+    AddCache(output_zip)
     CopyInfo(output_zip)
 
   print "cleaning up..."