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Fix gzip to deal with CRC's being signed values in Python 2.x properly and to

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read 32bit values as unsigned to start with rather than applying signedness
fixups allover the place afterwards.

This hopefully fixes the test_tarfile failure on the alpha/tru64 buildbot.
This commit is contained in:
Gregory P. Smith 2008-03-23 21:04:43 +00:00
parent 73f57b0c05
commit 79b4ba8fd7
1 changed files with 13 additions and 31 deletions
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44
Lib/gzip.py
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@ -16,28 +16,16 @@
READ, WRITE = 1, 2
def U32(i):
"""Return i as an unsigned integer, assuming it fits in 32 bits.
If it's >= 2GB when viewed as a 32-bit unsigned int, return a long.
"""
if i < 0:
i += 1L << 32
return i
def LOWU32(i):
"""Return the low-order 32 bits of an int, as a non-negative int."""
"""Return the low-order 32 bits, as a non-negative int or long."""
return i & 0xFFFFFFFFL
def write32(output, value):
output.write(struct.pack("<l", value))
def write32u(output, value):
# The L format writes the bit pattern correctly whether signed
# or unsigned.
output.write(struct.pack("<L", value))
def read32(input):
return struct.unpack("<l", input.read(4))[0]
return struct.unpack("<I", input.read(4))[0]
def open(filename, mode="rb", compresslevel=9):
"""Shorthand for GzipFile(filename, mode, compresslevel).
@ -141,7 +129,7 @@ def __repr__(self):
def _init_write(self, filename):
self.name = filename
self.crc = zlib.crc32("")
self.crc = zlib.crc32("") & 0xffffffffL
self.size = 0
self.writebuf = []
self.bufsize = 0
@ -163,7 +151,7 @@ def _write_gzip_header(self):
self.fileobj.write(fname + '\000')
def _init_read(self):
self.crc = zlib.crc32("")
self.crc = zlib.crc32("") & 0xffffffffL
self.size = 0
def _read_gzip_header(self):
@ -209,7 +197,7 @@ def write(self,data):
raise ValueError, "write() on closed GzipFile object"
if len(data) > 0:
self.size = self.size + len(data)
self.crc = zlib.crc32(data, self.crc)
self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
self.fileobj.write( self.compress.compress(data) )
self.offset += len(data)
@ -301,7 +289,7 @@ def _read(self, size=1024):
self._new_member = True
def _add_read_data(self, data):
self.crc = zlib.crc32(data, self.crc)
self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
self.extrabuf = self.extrabuf + data
self.extrasize = self.extrasize + len(data)
self.size = self.size + len(data)
@ -314,25 +302,19 @@ def _read_eof(self):
# stored is the true file size mod 2**32.
self.fileobj.seek(-8, 1)
crc32 = read32(self.fileobj)
isize = U32(read32(self.fileobj)) # may exceed 2GB
if U32(crc32) != U32(self.crc):
raise IOError("CRC check failed %s != %s" % (hex(U32(crc32)),
hex(U32(self.crc))))
elif isize != LOWU32(self.size):
isize = read32(self.fileobj) # may exceed 2GB
if crc32 != self.crc:
raise IOError("CRC check failed %s != %s" % (hex(crc32),
hex(self.crc)))
elif isize != self.size:
raise IOError, "Incorrect length of data produced"
def close(self):
if self.mode == WRITE:
self.fileobj.write(self.compress.flush())
# The native zlib crc is an unsigned 32-bit integer, but
# the Python wrapper implicitly casts that to a signed C
# long. So, on a 32-bit box self.crc may "look negative",
# while the same crc on a 64-bit box may "look positive".
# To avoid irksome warnings from the `struct` module, force
# it to look positive on all boxes.
write32u(self.fileobj, LOWU32(self.crc))
write32u(self.fileobj, self.crc)
# self.size may exceed 2GB, or even 4GB
write32u(self.fileobj, LOWU32(self.size))
write32u(self.fileobj, self.size)
self.fileobj = None
elif self.mode == READ:
self.fileobj = None