releasetools: Disable using imgdiff for squashfs.

We use imgdiff to handle files in zip format (e.g. jar/zip/apk) for
higher compression ratio.

For system/vendor in squashfs, a) all files are compressed in LZ4
format; b) we use 4096-byte block size in their sparse images, but the
files in squashfs may not be laid out as 4K-aligned. So the blocks for
a given file as listed in block map may not form a valid zip file, which
may fail the patch generation with imgdiff.

Disable using imgdiff for squashfs images, and use bsdiff instead.

Bug: 22322817
Change-Id: Ie76aa4cece5c9d38cb1d1a34c505a4a8f37512d3

tools/releasetools/blockimgdiff.py

@@ -261,7 +261,8 @@ class HeapItem(object):
 # original image.
 
 class BlockImageDiff(object):
-  def __init__(self, tgt, src=None, threads=None, version=4):
+  def __init__(self, tgt, src=None, threads=None, version=4,
+               disable_imgdiff=False):
     if threads is None:
       threads = multiprocessing.cpu_count() // 2
       if threads == 0:
@@ -274,6 +275,7 @@ class BlockImageDiff(object):
     self._max_stashed_size = 0
     self.touched_src_ranges = RangeSet()
     self.touched_src_sha1 = None
+    self.disable_imgdiff = disable_imgdiff
 
     assert version in (1, 2, 3, 4)
 
@@ -714,6 +716,7 @@ class BlockImageDiff(object):
             # produces significantly smaller patches than bsdiff).
             # This is permissible if:
             #
+            #  - imgdiff is not disabled, and
             #  - the source and target files are monotonic (ie, the
             #    data is stored with blocks in increasing order), and
             #  - we haven't removed any blocks from the source set.
@@ -723,7 +726,7 @@ class BlockImageDiff(object):
             # zip file (plus possibly extra zeros in the last block),
             # which is what imgdiff needs to operate.  (imgdiff is
             # fine with extra zeros at the end of the file.)
-            imgdiff = (xf.intact and
+            imgdiff = (not self.disable_imgdiff and xf.intact and
                        xf.tgt_name.split(".")[-1].lower()
                        in ("apk", "jar", "zip"))
             xf.style = "imgdiff" if imgdiff else "bsdiff"

tools/releasetools/common.py

@@ -1341,11 +1341,12 @@ def ComputeDifferences(diffs):
 
 class BlockDifference(object):
   def __init__(self, partition, tgt, src=None, check_first_block=False,
-               version=None):
+               version=None, disable_imgdiff=False):
     self.tgt = tgt
     self.src = src
     self.partition = partition
     self.check_first_block = check_first_block
+    self.disable_imgdiff = disable_imgdiff
 
     if version is None:
       version = 1
@@ -1356,7 +1357,8 @@ class BlockDifference(object):
     self.version = version
 
     b = blockimgdiff.BlockImageDiff(tgt, src, threads=OPTIONS.worker_threads,
-                                    version=self.version)
+                                    version=self.version,
+                                    disable_imgdiff=self.disable_imgdiff)
     tmpdir = tempfile.mkdtemp()
     OPTIONS.tempfiles.append(tmpdir)
     self.path = os.path.join(tmpdir, partition)

tools/releasetools/ota_from_target_files.py

@@ -863,9 +863,15 @@ def WriteBlockIncrementalOTAPackage(target_zip, source_zip, output_zip):
   # disk type is ext4
   system_partition = OPTIONS.source_info_dict["fstab"]["/system"]
   check_first_block = system_partition.fs_type == "ext4"
+  # Disable using imgdiff for squashfs. 'imgdiff -z' expects input files to be
+  # in zip formats. However with squashfs, a) all files are compressed in LZ4;
+  # b) the blocks listed in block map may not contain all the bytes for a given
+  # file (because they're rounded to be 4K-aligned).
+  disable_imgdiff = system_partition.fs_type == "squashfs"
   system_diff = common.BlockDifference("system", system_tgt, system_src,
                                        check_first_block,
-                                       version=blockimgdiff_version)
+                                       version=blockimgdiff_version,
+                                       disable_imgdiff=disable_imgdiff)
 
   if HasVendorPartition(target_zip):
     if not HasVendorPartition(source_zip):
@@ -879,9 +885,11 @@ def WriteBlockIncrementalOTAPackage(target_zip, source_zip, output_zip):
     # disk type is ext4
     vendor_partition = OPTIONS.source_info_dict["fstab"]["/vendor"]
     check_first_block = vendor_partition.fs_type == "ext4"
+    disable_imgdiff = vendor_partition.fs_type == "squashfs"
     vendor_diff = common.BlockDifference("vendor", vendor_tgt, vendor_src,
                                          check_first_block,
-                                         version=blockimgdiff_version)
+                                         version=blockimgdiff_version,
+                                         disable_imgdiff=disable_imgdiff)
   else:
     vendor_diff = None