def crc(self, cid, data):
"""Read and verify checksum"""
# Skip CRC checks for ancillary chunks if allowed to load truncated
# images
# 5th byte of first char is 1 [specs, section 5.4]
if ImageFile.LOAD_TRUNCATED_IMAGES and (PngImagePlugin.i8(cid[0]) >> 5
& 1):
self.crc_skip(cid, data)
return
try:
crc1 = PngImagePlugin._crc32(data, PngImagePlugin._crc32(cid))
crc2 = PngImagePlugin.i32(self.fp.read(4))
#if crc1 != crc2:
# raise SyntaxError("broken PNG file (bad header checksum in %r)"
# % cid)
except struct.error:
raise SyntaxError("broken PNG file (incomplete checksum in %r)" % cid)
