[Python-Dev] [Python-checkins] cpython (2.7): Issue #10276: test_zlib checks that inputs of 2 GB are handled correctly by (original) (raw)

Ethan Furman ethan at stoneleaf.us
Thu May 5 00:40:42 CEST 2011

Victor Stinner wrote:

Le mardi 03 mai 2011 à 16:22 +0200, Nadeem Vawda a écrit :

On Tue, May 3, 2011 at 3:19 PM, victor.stinner <python-checkins at python.org> wrote:

+# Issue #10276 - check that inputs of 2 GB are handled correctly. +# Be aware of issues #1202, #8650, #8651 and #10276 +class ChecksumBigBufferTestCase(unittest.TestCase): + intmax = 0x7FFFFFFF + + @unittest.skipUnless(mmap, "mmap() is not available.") + def testbigbuffer(self): + if sys.platform[:3] == 'win' or sys.platform == 'darwin': + requires('largefile', + 'test requires %s bytes and a long time to run' % + str(self.intmax)) + try: + with open(TESTFN, "wb+") as f: + f.seek(self.intmax-4) + f.write("asdf") + f.flush() + try: + m = mmap.mmap(f.fileno(), 0, access=mmap.ACCESSREAD) + self.assertEqual(zlib.crc32(m), 0x709418e7) + self.assertEqual(zlib.adler32(m), -2072837729) + finally: + m.close() + except (IOError, OverflowError): + raise unittest.SkipTest("filesystem doesn't have largefile support") + finally: + unlink(TESTFN) + + 0x7FFFFFFF is (2G-1) bytes. For a 2GB buffer, intmax should be 0x80000000. However, if you make this change, crc32() and adler32() raise OverflowErrors (see changeset a0681e7a6ded). I don't want to check OverflowError: the test is supposed to compute the checksum of a buffer of 0x7FFFFFFF bytes

The comment says 'check that inputs of 2 GB are handled correctly' but the file created is 1 byte short of 2Gb. Is the test wrong, or just wrongly commented? Or am I not understanding?

Ethan

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