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Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
"""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, os
import zlib
import io
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("'
def _check_closed(self):
"""Raises a ValueError if the underlying file object has been closed.
"""
if self.closed:
raise ValueError('I/O operation on closed file.')
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 = os.path.basename(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_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 != '\037\213':
raise IOError, 'Not a gzipped file'
method, flag, self.mtime = struct.unpack(" 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)
return len(data)
def read(self, size=-1):
self._check_closed()
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
while self._read(readsize):
readsize = min(self.max_read_chunk, readsize * 2)
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)
offset = self.offset - self.extrastart
chunk = self.extrabuf[offset: offset + size]
self.extrasize = self.extrasize - size
self.offset += size
return chunk
def _unread(self, buf):
self.extrasize = len(buf) + self.extrasize
self.offset -= len(buf)
def _read(self, size=1024):
if self.fileobj is None:
return False
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():
return False
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.fileobj.seek(-len(self.decompress.unused_data), 1)
self._read_eof()
self._add_read_data( uncompress )
return False
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)
self.fileobj.seek(-len(self.decompress.unused_data), 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
return True
def _add_read_data(self, data):
self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
offset = self.offset - self.extrastart
self.extrabuf = self.extrabuf[offset:] + data
self.extrasize = self.extrasize + len(data)
self.extrastart = self.offset
self.size = self.size + len(data)
def _read_eof(self):
# We've read to the end of the file.
# 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(" 0:
self.extrasize -= i - offset
self.offset += i - offset
return self.extrabuf[offset: i]
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 _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()