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bpo-6584: Add a BadGzipFile exception to the gzip module. (GH-13022)

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Co-Authored-By: Filip Gruszczyński <gruszczy@gmail.com>
Co-Authored-By: Michele Orrù <maker@tumbolandia.net>
This commit is contained in:
Zackery Spytz 2019-05-13 01:50:52 -06:00 • committed by Serhiy Storchaka
parent d28772ab69
commit cf599f6f6f
5 changed files with 34 additions and 6 deletions
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17
Lib/gzip.py
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@ -11,7 +11,7 @@ import builtins
import io
import _compression
__all__ = ["GzipFile", "open", "compress", "decompress"]
__all__ = ["BadGzipFile", "GzipFile", "open", "compress", "decompress"]
FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
@ -112,6 +112,11 @@ class _PaddedFile:
def seekable(self):
return True # Allows fast-forwarding even in unseekable streams
class BadGzipFile(OSError):
"""Exception raised in some cases for invalid gzip files."""
class GzipFile(_compression.BaseStream):
"""The GzipFile class simulates most of the methods of a file object with
the exception of the truncate() method.
@ -413,12 +418,12 @@ class _GzipReader(_compression.DecompressReader):
return False
if magic != b'\037\213':
raise OSError('Not a gzipped file (%r)' % magic)
raise BadGzipFile('Not a gzipped file (%r)' % magic)
(method, flag,
self._last_mtime) = struct.unpack("<BBIxx", self._read_exact(8))
if method != 8:
raise OSError('Unknown compression method')
raise BadGzipFile('Unknown compression method')
if flag & FEXTRA:
# Read & discard the extra field, if present
@ -502,10 +507,10 @@ class _GzipReader(_compression.DecompressReader):
# stored is the true file size mod 2**32.
crc32, isize = struct.unpack("<II", self._read_exact(8))
if crc32 != self._crc:
raise OSError("CRC check failed %s != %s" % (hex(crc32),
hex(self._crc)))
raise BadGzipFile("CRC check failed %s != %s" % (hex(crc32),
hex(self._crc)))
elif isize != (self._stream_size & 0xffffffff):
raise OSError("Incorrect length of data produced")
raise BadGzipFile("Incorrect length of data produced")
# Gzip files can be padded with zeroes and still have archives.
# Consume all zero bytes and set the file position to the first