Fix gzip payload failure on python 2.6 (4a7d6b96) · Commits · Seblu / installsystems

installsystems/gzip.py

0 → 100644

+488 −0

Original line number	Diff line number	Diff line
		"""Functions that read and write gzipped files.

		The user of the file doesn't have to worry about the compression,
		but random access is not allowed."""

		# based on Andrew Kuchling's minigzip.py distributed with the zlib module

		import struct, sys, time
		import zlib
		import __builtin__

		__all__ = ["GzipFile","open"]

		FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16

		READ, WRITE = 1, 2

		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("<I", input.read(4))[0]

		def open(filename, mode="rb", compresslevel=9):
		"""Shorthand for GzipFile(filename, mode, compresslevel).

		The filename argument is required; mode defaults to 'rb'
		and compresslevel defaults to 9.

		"""
		return GzipFile(filename, mode, compresslevel)

		class GzipFile:
		"""The GzipFile class simulates most of the methods of a file object with
		the exception of the readinto() and truncate() methods.

		"""

		myfileobj = None
		max_read_chunk = 10 * 1024 * 1024 # 10Mb

		def __init__(self, filename=None, mode=None,
		compresslevel=9, fileobj=None, mtime=None):
		"""Constructor for the GzipFile class.

		At least one of fileobj and filename must be given a
		non-trivial value.

		The new class instance is based on fileobj, which can be a regular
		file, a StringIO object, or any other object which simulates a file.
		It defaults to None, in which case filename is opened to provide
		a file object.

		When fileobj is not None, the filename argument is only used to be
		included in the gzip file header, which may includes the original
		filename of the uncompressed file. It defaults to the filename of
		fileobj, if discernible; otherwise, it defaults to the empty string,
		and in this case the original filename is not included in the header.

		The mode argument can be any of 'r', 'rb', 'a', 'ab', 'w', or 'wb',
		depending on whether the file will be read or written. The default
		is the mode of fileobj if discernible; otherwise, the default is 'rb'.
		Be aware that only the 'rb', 'ab', and 'wb' values should be used
		for cross-platform portability.

		The compresslevel argument is an integer from 1 to 9 controlling the
		level of compression; 1 is fastest and produces the least compression,
		and 9 is slowest and produces the most compression. The default is 9.

		"""

		# guarantee the file is opened in binary mode on platforms
		# that care about that sort of thing
		if mode and 'b' not in mode:
		mode += 'b'
		if fileobj is None:
		fileobj = self.myfileobj = __builtin__.open(filename, mode or 'rb')
		if filename is None:
		if hasattr(fileobj, 'name'): filename = fileobj.name
		else: filename = ''
		if mode is None:
		if hasattr(fileobj, 'mode'): mode = fileobj.mode
		else: mode = 'rb'

		if mode[0:1] == 'r':
		self.mode = READ
		# Set flag indicating start of a new member
		self._new_member = True
		self.extrabuf = ""
		self.extrasize = 0
		self.name = filename
		# Starts small, scales exponentially
		self.min_readsize = 100

		elif mode[0:1] == 'w' or mode[0:1] == 'a':
		self.mode = WRITE
		self._init_write(filename)
		self.compress = zlib.compressobj(compresslevel,
		zlib.DEFLATED,
		-zlib.MAX_WBITS,
		zlib.DEF_MEM_LEVEL,
		0)
		else:
		raise IOError, "Mode " + mode + " not supported"

		self.fileobj = fileobj
		self.mtime = mtime
		self.offset = 0

		if self.mode == WRITE:
		self._write_gzip_header()

		@property
		def filename(self):
		import warnings
		warnings.warn("use the name attribute", DeprecationWarning, 2)
		if self.mode == WRITE and self.name[-3:] != ".gz":
		return self.name + ".gz"
		return self.name

		def __repr__(self):
		s = repr(self.fileobj)
		return '<gzip ' + s[1:-1] + ' ' + hex(id(self)) + '>'

		def _init_write(self, filename):
		self.name = filename
		self.crc = zlib.crc32("") & 0xffffffffL
		self.size = 0
		self.writebuf = []
		self.bufsize = 0

		def _write_gzip_header(self):
		self.fileobj.write('\037\213') # magic header
		self.fileobj.write('\010') # compression method
		fname = self.name
		if fname.endswith(".gz"):
		fname = fname[:-3]
		flags = 0
		if fname:
		flags = FNAME
		self.fileobj.write(chr(flags))
		mtime = self.mtime
		if mtime is None:
		mtime = time.time()
		write32u(self.fileobj, long(mtime))
		self.fileobj.write('\002')
		self.fileobj.write('\377')
		if fname:
		self.fileobj.write(fname + '\000')

		def _init_read(self):
		self.crc = zlib.crc32("") & 0xffffffffL
		self.size = 0

		def _read_gzip_header(self):
		magic = self.fileobj.read(2)
		if magic != '\037\213':
		raise IOError, 'Not a gzipped file'
		method = ord( self.fileobj.read(1) )
		if method != 8:
		raise IOError, 'Unknown compression method'
		flag = ord( self.fileobj.read(1) )
		self.mtime = self.fileobj.read(4)
		# extraflag = self.fileobj.read(1)
		# os = self.fileobj.read(1)
		self.fileobj.read(2)

		if flag & FEXTRA:
		# Read & discard the extra field, if present
		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:
		s = self.fileobj.read(1)
		if not s or s=='\000':
		break
		if flag & FCOMMENT:
		# Read and discard a null-terminated string containing a comment
		while True:
		s = self.fileobj.read(1)
		if not s or s=='\000':
		break
		if flag & FHCRC:
		self.fileobj.read(2) # Read & discard the 16-bit header CRC


		def write(self,data):
		if self.mode != WRITE:
		import errno
		raise IOError(errno.EBADF, "write() on read-only GzipFile object")

		if self.fileobj is None:
		raise ValueError, "write() on closed GzipFile object"
		if len(data) > 0:
		self.size = self.size + len(data)
		self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
		self.fileobj.write( self.compress.compress(data) )
		self.offset += len(data)

		def read(self, size=-1):
		if self.mode != READ:
		import errno
		raise IOError(errno.EBADF, "read() on write-only GzipFile object")

		if self.extrasize <= 0 and self.fileobj is None:
		return ''

		readsize = 1024
		if size < 0: # get the whole thing
		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
		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

		chunk = self.extrabuf[:size]
		self.extrabuf = self.extrabuf[size:]
		self.extrasize = self.extrasize - size

		self.offset += size
		return chunk

		def _unread(self, buf):
		self.extrabuf = buf + self.extrabuf
		self.extrasize = len(buf) + self.extrasize
		self.offset -= len(buf)

		def _read(self, size=1024):
		if self.fileobj is None:
		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.
		#
		# First, check if we're at the end of the file;
		# if so, it's time to stop; no more members to read.
		pos = self.fileobj.tell() # Save current position
		self.fileobj.seek(0, 2) # Seek to end of file
		if pos == self.fileobj.tell():
		raise EOFError, "Reached EOF"
		else:
		self.fileobj.seek( pos ) # Return to original position

		self._init_read()
		self._read_gzip_header()
		self.decompress = zlib.decompressobj(-zlib.MAX_WBITS)
		self._new_member = False

		# Read a chunk of data from the file
		buf = self.fileobj.read(size)

		# If the EOF has been reached, flush the decompression object
		# and mark this object as finished.

		if buf == "":
		uncompress = self.decompress.flush()
		self._read_eof()
		self._add_read_data( uncompress )
		raise EOFError, 'Reached EOF'

		uncompress = self.decompress.decompress(buf)
		self._add_read_data( uncompress )

		if self.decompress.unused_data != "":
		# Ending case: we've come to the end of a member in the file,
		# so seek back to the start of the unused data, finish up
		# this member, and read a new gzip header.
		# (The number of bytes to seek back is the length of the unused
		# data, minus 8 because _read_eof() will rewind a further 8 bytes)
		self.fileobj.seek( -len(self.decompress.unused_data)+8, 1)

		# Check the CRC and file size, and set the flag so we read
		# a new member on the next call
		self._read_eof()
		self._new_member = True

		def _add_read_data(self, data):
		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)

		def _read_eof(self):
		# We've read to the end of the file, so we have to rewind in order
		# to reread the 8 bytes containing the CRC and the file size.
		# 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.
		self.fileobj.seek(-8, 1)
		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)))
		elif isize != (self.size & 0xffffffffL):
		raise IOError, "Incorrect length of data produced"

		def close(self):
		if self.fileobj is None:
		return
		if self.mode == WRITE:
		self.fileobj.write(self.compress.flush())
		write32u(self.fileobj, self.crc)
		# self.size may exceed 2GB, or even 4GB
		write32u(self.fileobj, self.size & 0xffffffffL)
		self.fileobj = None
		elif self.mode == READ:
		self.fileobj = None
		if self.myfileobj:
		self.myfileobj.close()
		self.myfileobj = None

		def __del__(self):
		try:
		if (self.myfileobj is None and
		self.fileobj is None):
		return
		except AttributeError:
		return
		self.close()

		def flush(self,zlib_mode=zlib.Z_SYNC_FLUSH):
		if self.mode == WRITE:
		# Ensure the compressor's buffer is flushed
		self.fileobj.write(self.compress.flush(zlib_mode))
		self.fileobj.flush()

		def fileno(self):
		"""Invoke the underlying file object's fileno() method.

		This will raise AttributeError if the underlying file object
		doesn't support fileno().
		"""
		return self.fileobj.fileno()

		def isatty(self):
		return False

		def tell(self):
		return self.offset

		def rewind(self):
		'''Return the uncompressed stream file position indicator to the
		beginning of the file'''
		if self.mode != READ:
		raise IOError("Can't rewind in write mode")
		self.fileobj.seek(0)
		self._new_member = True
		self.extrabuf = ""
		self.extrasize = 0
		self.offset = 0

		def seek(self, offset, whence=0):
		if whence:
		if whence == 1:
		offset = self.offset + offset
		else:
		raise ValueError('Seek from end not supported')
		if self.mode == WRITE:
		if offset < self.offset:
		raise IOError('Negative seek in write mode')
		count = offset - self.offset
		for i in range(count // 1024):
		self.write(1024 * '\0')
		self.write((count % 1024) * '\0')
		elif self.mode == READ:
		if offset < self.offset:
		# for negative seek, rewind and do positive seek
		self.rewind()
		count = offset - self.offset
		for i in range(count // 1024):
		self.read(1024)
		self.read(count % 1024)

		def readline(self, size=-1):
		if size < 0:
		size = sys.maxint
		readsize = self.min_readsize
		else:
		readsize = size
		bufs = []
		while size != 0:
		c = self.read(readsize)
		i = c.find('\n')

		# We set i=size to break out of the loop under two
		# conditions: 1) there's no newline, and the chunk is
		# larger than size, or 2) there is a newline, but the
		# resulting line would be longer than 'size'.
		if (size <= i) or (i == -1 and len(c) > size):
		i = size - 1

		if i >= 0 or c == '':
		bufs.append(c[:i + 1]) # Add portion of last chunk
		self._unread(c[i + 1:]) # Push back rest of chunk
		break

		# Append chunk to list, decrease 'size',
		bufs.append(c)
		size = size - len(c)
		readsize = min(size, readsize * 2)
		if readsize > self.min_readsize:
		self.min_readsize = min(readsize, self.min_readsize * 2, 512)
		return ''.join(bufs) # Return resulting line

		def readlines(self, sizehint=0):
		# Negative numbers result in reading all the lines
		if sizehint <= 0:
		sizehint = sys.maxint
		L = []
		while sizehint > 0:
		line = self.readline()
		if line == "":
		break
		L.append(line)
		sizehint = sizehint - len(line)

		return L

		def writelines(self, L):
		for line in L:
		self.write(line)

		def __iter__(self):
		return self

		def next(self):
		line = self.readline()
		if line:
		return line
		else:
		raise StopIteration


		def _test():
		# Act like gzip; with -d, act like gunzip.
		# The input file is not deleted, however, nor are any other gzip
		# options or features supported.
		args = sys.argv[1:]
		decompress = args and args[0] == "-d"
		if decompress:
		args = args[1:]
		if not args:
		args = ["-"]
		for arg in args:
		if decompress:
		if arg == "-":
		f = GzipFile(filename="", mode="rb", fileobj=sys.stdin)
		g = sys.stdout
		else:
		if arg[-3:] != ".gz":
		print "filename doesn't end in .gz:", repr(arg)
		continue
		f = open(arg, "rb")
		g = __builtin__.open(arg[:-3], "wb")
		else:
		if arg == "-":
		f = sys.stdin
		g = GzipFile(filename="", mode="wb", fileobj=sys.stdout)
		else:
		f = __builtin__.open(arg, "rb")
		g = open(arg + ".gz", "wb")
		while True:
		chunk = f.read(1024)
		if not chunk:
		break
		g.write(chunk)
		if g is not sys.stdout:
		g.close()
		if f is not sys.stdin:
		f.close()

		if __name__ == '__main__':
		_test()