[Python-checkins] cpython (merge 3.5 -> 3.6): Issue #28449: tarfile.open() with mode "r" or "r:" now tries to open a tar

Sun Oct 30 14:59:04 EDT 2016

https://hg.python.org/cpython/rev/de8e83262644
changeset: 104833:de8e83262644
branch: 3.6
parent: 104829:0a985f7c6731
parent: 104831:f108e063e299
user: Serhiy Storchaka <storchaka at gmail.com>
date: Sun Oct 30 20:56:23 2016 +0200
summary:
 Issue #28449: tarfile.open() with mode "r" or "r:" now tries to open a tar
file with compression before trying to open it without compression. Otherwise
it had 50% chance failed with ignore_zeros=True.
files:
 Lib/tarfile.py | 4 +++-
 Lib/test/test_tarfile.py | 8 +++++++-
 Misc/NEWS | 5 ++++-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -1554,7 +1554,9 @@
 
 if mode in ("r", "r:*"):
 # Find out which *open() is appropriate for opening the file.
- for comptype in cls.OPEN_METH:
+ def not_compressed(comptype):
+ return cls.OPEN_METH[comptype] == 'taropen'
+ for comptype in sorted(cls.OPEN_METH, key=not_compressed):
 func = getattr(cls, cls.OPEN_METH[comptype])
 if fileobj is not None:
 saved_pos = fileobj.tell()
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -3,6 +3,7 @@
 import io
 from hashlib import md5
 from contextlib import contextmanager
+from random import Random
 
 import unittest
 import unittest.mock
@@ -349,12 +350,17 @@
 
 def test_ignore_zeros(self):
 # Test TarFile's ignore_zeros option.
+ # generate 512 pseudorandom bytes
+ data = Random(0).getrandbits(512*8).to_bytes(512, 'big')
 for char in (b'0円', b'a'):
 # Test if EOFHeaderError ('0円') and InvalidHeaderError ('a')
 # are ignored correctly.
 with self.open(tmpname, "w") as fobj:
 fobj.write(char * 1024)
- fobj.write(tarfile.TarInfo("foo").tobuf())
+ tarinfo = tarfile.TarInfo("foo")
+ tarinfo.size = len(data)
+ fobj.write(tarinfo.tobuf())
+ fobj.write(data)
 
 tar = tarfile.open(tmpname, mode="r", ignore_zeros=True)
 try:
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,10 +27,13 @@
 - Issue #28471: Fix "Python memory allocator called without holding the GIL"
 crash in socket.setblocking.
 
-
 Library
 -------
 
+- Issue #28449: tarfile.open() with mode "r" or "r:" now tries to open a tar
+ file with compression before trying to open it without compression. Otherwise
+ it had 50% chance failed with ignore_zeros=True.
+
 - Issue #23262: The webbrowser module now supports Firefox 36+ and derived
 browsers. Based on patch by Oleg Broytman.
 
-- 
Repository URL: https://hg.python.org/cpython
