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Back out patch for #1159051, which caused backwards compatibility problems.

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This commit is contained in:
Georg Brandl 2013-05-12 11:57:26 +02:00
parent 64949fa20e
commit b3bd624a55
5 changed files with 44 additions and 82 deletions
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81
Lib/gzip.py
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@ -65,6 +65,9 @@ def write32u(output, value):
# or unsigned.
output.write(struct.pack("<L", value))
def read32(input):
return struct.unpack("<I", input.read(4))[0]
class _PaddedFile:
"""Minimal read-only file object that prepends a string to the contents
of an actual file. Shouldn't be used outside of gzip.py, as it lacks
@ -278,32 +281,28 @@ class GzipFile(io.BufferedIOBase):
self.crc = zlib.crc32(b"") & 0xffffffff
self.size = 0
def _read_exact(self, n):
data = self.fileobj.read(n)
while len(data) < n:
b = self.fileobj.read(n - len(data))
if not b:
raise EOFError("Compressed file ended before the "
"end-of-stream marker was reached")
data += b
return data
def _read_gzip_header(self):
magic = self.fileobj.read(2)
if magic == b'':
return False
raise EOFError("Reached EOF")
if magic != b'\037\213':
raise IOError('Not a gzipped file')
method, flag, self.mtime = struct.unpack("<BBIxx", self._read_exact(8))
method = ord( self.fileobj.read(1) )
if method != 8:
raise IOError('Unknown compression method')
flag = ord( self.fileobj.read(1) )
self.mtime = read32(self.fileobj)
# extraflag = self.fileobj.read(1)
# os = self.fileobj.read(1)
self.fileobj.read(2)
if flag & FEXTRA:
# Read & discard the extra field, if present
extra_len, = struct.unpack("<H", self._read_exact(2))
self._read_exact(extra_len)
xlen = ord(self.fileobj.read(1))
xlen = xlen + 256*ord(self.fileobj.read(1))
self.fileobj.read(xlen)
if flag & FNAME:
# Read and discard a null-terminated string containing the filename
while True:
@ -317,13 +316,12 @@ class GzipFile(io.BufferedIOBase):
if not s or s==b'\000':
break
if flag & FHCRC:
self._read_exact(2) # Read & discard the 16-bit header CRC
self.fileobj.read(2) # Read & discard the 16-bit header CRC
unused = self.fileobj.unused()
if unused:
uncompress = self.decompress.decompress(unused)
self._add_read_data(uncompress)
return True
def write(self,data):
self._check_closed()
@ -357,16 +355,20 @@ class GzipFile(io.BufferedIOBase):
readsize = 1024
if size < 0: # get the whole thing
while self._read(readsize):
readsize = min(self.max_read_chunk, readsize * 2)
size = self.extrasize
try:
while True:
self._read(readsize)
readsize = min(self.max_read_chunk, readsize * 2)
except EOFError:
size = self.extrasize
else: # just get some more of it
while size > self.extrasize:
if not self._read(readsize):
if size > self.extrasize:
size = self.extrasize
break
readsize = min(self.max_read_chunk, readsize * 2)
try:
while size > self.extrasize:
self._read(readsize)
readsize = min(self.max_read_chunk, readsize * 2)
except EOFError:
if size > self.extrasize:
size = self.extrasize
offset = self.offset - self.extrastart
chunk = self.extrabuf[offset: offset + size]
@ -384,9 +386,12 @@ class GzipFile(io.BufferedIOBase):
if self.extrasize <= 0 and self.fileobj is None:
return b''
# For certain input data, a single call to _read() may not return
# any data. In this case, retry until we get some data or reach EOF.
while self.extrasize <= 0 and self._read():
try:
# For certain input data, a single call to _read() may not return
# any data. In this case, retry until we get some data or reach EOF.
while self.extrasize <= 0:
self._read()
except EOFError:
pass
if size < 0 or size > self.extrasize:
size = self.extrasize
@ -409,9 +414,12 @@ class GzipFile(io.BufferedIOBase):
if self.extrasize == 0:
if self.fileobj is None:
return b''
# Ensure that we don't return b"" if we haven't reached EOF.
# 1024 is the same buffering heuristic used in read()
while self.extrasize == 0 and self._read(max(n, 1024)):
try:
# Ensure that we don't return b"" if we haven't reached EOF.
while self.extrasize == 0:
# 1024 is the same buffering heuristic used in read()
self._read(max(n, 1024))
except EOFError:
pass
offset = self.offset - self.extrastart
remaining = self.extrasize
@ -424,14 +432,13 @@ class GzipFile(io.BufferedIOBase):
def _read(self, size=1024):
if self.fileobj is None:
return False
raise EOFError("Reached EOF")
if self._new_member:
# If the _new_member flag is set, we have to
# jump to the next member, if there is one.
self._init_read()
if not self._read_gzip_header():
return False
self._read_gzip_header()
self.decompress = zlib.decompressobj(-zlib.MAX_WBITS)
self._new_member = False
@ -448,7 +455,7 @@ class GzipFile(io.BufferedIOBase):
self.fileobj.prepend(self.decompress.unused_data, True)
self._read_eof()
self._add_read_data( uncompress )
return False
raise EOFError('Reached EOF')
uncompress = self.decompress.decompress(buf)
self._add_read_data( uncompress )
@ -464,7 +471,6 @@ class GzipFile(io.BufferedIOBase):
# a new member on the next call
self._read_eof()
self._new_member = True
return True
def _add_read_data(self, data):
self.crc = zlib.crc32(data, self.crc) & 0xffffffff
@ -479,7 +485,8 @@ class GzipFile(io.BufferedIOBase):
# We check the that the computed CRC and size of the
# uncompressed data matches the stored values. Note that the size
# stored is the true file size mod 2**32.
crc32, isize = struct.unpack("<II", self._read_exact(8))
crc32 = read32(self.fileobj)
isize = read32(self.fileobj) # may exceed 2GB
if crc32 != self.crc:
raise IOError("CRC check failed %s != %s" % (hex(crc32),
hex(self.crc)))