blocksize = 4096
care_map = RangeSet()
clobbered_blocks = RangeSet()
+ extended = RangeSet()
total_blocks = 0
file_map = {}
def ReadRangeSet(self, ranges):
self.total_blocks = len(self.data) / self.blocksize
self.care_map = RangeSet(data=(0, self.total_blocks))
self.clobbered_blocks = RangeSet()
+ self.extended = RangeSet()
zero_blocks = []
nonzero_blocks = []
elif self.version >= 3:
# take into account automatic stashing of overlapping blocks
if xf.src_ranges.overlaps(xf.tgt_ranges):
- temp_stash_usage = stashed_blocks + xf.src_ranges.size();
+ temp_stash_usage = stashed_blocks + xf.src_ranges.size()
if temp_stash_usage > max_stashed_blocks:
max_stashed_blocks = temp_stash_usage
elif self.version >= 3:
# take into account automatic stashing of overlapping blocks
if xf.src_ranges.overlaps(xf.tgt_ranges):
- temp_stash_usage = stashed_blocks + xf.src_ranges.size();
+ temp_stash_usage = stashed_blocks + xf.src_ranges.size()
if temp_stash_usage > max_stashed_blocks:
max_stashed_blocks = temp_stash_usage
# stash space
assert max_stashed_blocks * self.tgt.blocksize < (512 << 20)
+ # Zero out extended blocks as a workaround for bug 20881595.
+ if self.tgt.extended:
+ out.append("zero %s\n" % (self.tgt.extended.to_string_raw(),))
+
+ # We erase all the blocks on the partition that a) don't contain useful
+ # data in the new image and b) will not be touched by dm-verity.
all_tgt = RangeSet(data=(0, self.tgt.total_blocks))
- if performs_read:
- # if some of the original data is used, then at the end we'll
- # erase all the blocks on the partition that don't contain data
- # in the new image.
- new_dontcare = all_tgt.subtract(self.tgt.care_map)
- if new_dontcare:
- out.append("erase %s\n" % (new_dontcare.to_string_raw(),))
- else:
- # if nothing is read (ie, this is a full OTA), then we can start
- # by erasing the entire partition.
- out.insert(0, "erase %s\n" % (all_tgt.to_string_raw(),))
+ all_tgt_minus_extended = all_tgt.subtract(self.tgt.extended)
+ new_dontcare = all_tgt_minus_extended.subtract(self.tgt.care_map)
+ if new_dontcare:
+ out.append("erase %s\n" % (new_dontcare.to_string_raw(),))
out.insert(0, "%d\n" % (self.version,)) # format version number
out.insert(1, str(total) + "\n")
script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' % (
self.device, ranges_str,
self.tgt.TotalSha1(include_clobbered_blocks=True)))
- script.Print('Verified the updated %s image.' % (partition,))
+
+ # Bug: 20881595
+ # Verify that extended blocks are really zeroed out.
+ if self.tgt.extended:
+ ranges_str = self.tgt.extended.to_string_raw()
+ script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' % (
+ self.device, ranges_str,
+ self._HashZeroBlocks(self.tgt.extended.size())))
+ script.Print('Verified the updated %s image.' % (partition,))
+ script.AppendExtra(
+ 'else\n'
+ ' abort("%s partition has unexpected non-zero contents after OTA '
+ 'update");\n'
+ 'endif;' % (partition,))
+ else:
+ script.Print('Verified the updated %s image.' % (partition,))
+
script.AppendExtra(
'else\n'
' abort("%s partition has unexpected contents after OTA update");\n'
return ctx.hexdigest()
+ def _HashZeroBlocks(self, num_blocks): # pylint: disable=no-self-use
+ """Return the hash value for all zero blocks."""
+ zero_block = '\x00' * 4096
+ ctx = sha1()
+ for _ in range(num_blocks):
+ ctx.update(zero_block)
+
+ return ctx.hexdigest()
+
# TODO(tbao): Due to http://b/20939131, block 0 may be changed without
# remounting R/W. Will change the checking to a finer-grained way to
# mask off those bits.
out.append(offset + p - start)
return RangeSet(data=out)
+ def extend(self, n):
+ """Extend the RangeSet by 'n' blocks.
+
+ The lower bound is guaranteed to be non-negative.
+
+ >>> RangeSet("0-9").extend(1)
+ <RangeSet("0-10")>
+ >>> RangeSet("10-19").extend(15)
+ <RangeSet("0-34")>
+ >>> RangeSet("10-19 30-39").extend(4)
+ <RangeSet("6-23 26-43")>
+ >>> RangeSet("10-19 30-39").extend(10)
+ <RangeSet("0-49")>
+ """
+ out = self
+ for i in range(0, len(self.data), 2):
+ s, e = self.data[i:i+2]
+ s1 = max(0, s - n)
+ e1 = e + n
+ out = out.union(RangeSet(str(s1) + "-" + str(e1-1)))
+ return out
+
if __name__ == "__main__":
import doctest
self.care_map = rangelib.RangeSet(care_data)
self.offset_index = [i[0] for i in offset_map]
+ # Bug: 20881595
+ # Introduce extended blocks as a workaround for the bug. dm-verity may
+ # touch blocks that are not in the care_map due to block device
+ # read-ahead. It will fail if such blocks contain non-zeroes. We zero out
+ # the extended blocks explicitly to avoid dm-verity failures. 512 blocks
+ # are the maximum read-ahead we configure for dm-verity block devices.
+ extended = self.care_map.extend(512)
+ all_blocks = rangelib.RangeSet(data=(0, self.total_blocks))
+ extended = extended.intersect(all_blocks).subtract(self.care_map)
+ self.extended = extended
+
if file_map_fn:
self.LoadFileBlockMap(file_map_fn, self.clobbered_blocks)
else: