refactor BlockDifference into common

Move BlockDifference into common and make its script generation code
more complete, so that it can be use by releasetools.py to do diffs on
baseband images.

Bug: 16984795
Change-Id: Iba9afc1c7755458ce47468b5170672612b2cb4b3

tools/releasetools/common.py

@@ -29,6 +29,8 @@ import threading
 import time
 import zipfile
 
+import blockimgdiff
+
 try:
   from hashlib import sha1 as sha1
 except ImportError:
@@ -1010,6 +1012,60 @@ def ComputeDifferences(diffs):
     threads.pop().join()
 
 
+class BlockDifference:
+  def __init__(self, partition, tgt, src=None):
+    self.tgt = tgt
+    self.src = src
+    self.partition = partition
+
+    b = blockimgdiff.BlockImageDiff(tgt, src, threads=OPTIONS.worker_threads)
+    tmpdir = tempfile.mkdtemp()
+    OPTIONS.tempfiles.append(tmpdir)
+    self.path = os.path.join(tmpdir, partition)
+    b.Compute(self.path)
+
+    _, self.device = GetTypeAndDevice("/" + partition, OPTIONS.info_dict)
+
+  def WriteScript(self, script, output_zip, progress=None):
+    if not self.src:
+      # write the output unconditionally
+      if progress: script.ShowProgress(progress, 0)
+      self._WriteUpdate(script, output_zip)
+
+    else:
+      script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' %
+                         (self.device, self.src.care_map.to_string_raw(),
+                          self.src.TotalSha1()))
+      script.Print("Patching %s image..." % (self.partition,))
+      if progress: script.ShowProgress(progress, 0)
+      self._WriteUpdate(script, output_zip)
+      script.AppendExtra(('else\n'
+                          '  (range_sha1("%s", "%s") == "%s") ||\n'
+                          '  abort("%s partition has unexpected contents");\n'
+                          'endif;') %
+                         (self.device, self.tgt.care_map.to_string_raw(),
+                          self.tgt.TotalSha1(), self.partition))
+
+  def _WriteUpdate(self, script, output_zip):
+    partition = self.partition
+    with open(self.path + ".transfer.list", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".transfer.list", f.read())
+    with open(self.path + ".new.dat", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".new.dat", f.read())
+    with open(self.path + ".patch.dat", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".patch.dat", f.read(),
+                         compression=zipfile.ZIP_STORED)
+
+    call = (('block_image_update("%s", '
+             'package_extract_file("%s.transfer.list"), '
+             '"%s.new.dat", "%s.patch.dat");\n') %
+            (self.device, partition, partition, partition))
+    script.AppendExtra(script._WordWrap(call))
+
+
+DataImage = blockimgdiff.DataImage
+
+
 # map recovery.fstab's fs_types to mount/format "partition types"
 PARTITION_TYPES = { "yaffs2": "MTD", "mtd": "MTD",
                     "ext4": "EMMC", "emmc": "EMMC",