diff options
Diffstat (limited to 'Lib/gzip.py')
| -rw-r--r-- | Lib/gzip.py | 44 |
1 files changed, 13 insertions, 31 deletions
diff --git a/Lib/gzip.py b/Lib/gzip.py index 5d8761e..f3cf9fe 100644 --- a/Lib/gzip.py +++ b/Lib/gzip.py @@ -16,28 +16,16 @@ FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 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 @@ class GzipFile: 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 @@ class GzipFile: 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 @@ class GzipFile: 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 @@ class GzipFile: 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 @@ class GzipFile: # 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 |