FM / zlib

/usr/lib64/python2.7/Demo/zlib

Name	Size	Mode	Actions
minigzip.py	4304	0755	edit dl rm
minigzip.pyc	3645	0644	edit dl rm
minigzip.pyo	3645	0644	edit dl rm
zlibdemo.py	1469	0755	edit dl rm
zlibdemo.pyc	1243	0644	edit dl rm
zlibdemo.pyo	1243	0644	edit dl rm

Edit: /usr/lib64/python2.7/Demo/zlib/minigzip.py (4304B)

#! /usr/bin/python2.7
# Demo program for zlib; it compresses or decompresses files, but *doesn't*
# delete the original.  This doesn't support all of gzip's options.
#
# The 'gzip' module in the standard library provides a more complete
# implementation of gzip-format files.

import zlib, sys, os

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

def write32(output, value):
    output.write(chr(value & 255)) ; value=value // 256
    output.write(chr(value & 255)) ; value=value // 256
    output.write(chr(value & 255)) ; value=value // 256
    output.write(chr(value & 255))

def read32(input):
    v = ord(input.read(1))
    v += (ord(input.read(1)) << 8 )
    v += (ord(input.read(1)) << 16)
    v += (ord(input.read(1)) << 24)
    return v

def compress (filename, input, output):
    output.write('\037\213\010')        # Write the header, ...
    output.write(chr(FNAME))            # ... flag byte ...

statval = os.stat(filename)           # ... modification time ...
    mtime = statval[8]
    write32(output, mtime)
    output.write('\002')                # ... slowest compression alg. ...
    output.write('\377')                # ... OS (=unknown) ...
    output.write(filename+'\000')       # ... original filename ...

crcval = zlib.crc32("")
    compobj = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS,
                             zlib.DEF_MEM_LEVEL, 0)
    while True:
        data = input.read(1024)
        if data == "":
            break
        crcval = zlib.crc32(data, crcval)
        output.write(compobj.compress(data))
    output.write(compobj.flush())
    write32(output, crcval)             # ... the CRC ...
    write32(output, statval[6])         # and the file size.

def decompress (input, output):
    magic = input.read(2)
    if magic != '\037\213':
        print 'Not a gzipped file'
        sys.exit(0)
    if ord(input.read(1)) != 8:
        print 'Unknown compression method'
        sys.exit(0)
    flag = ord(input.read(1))
    input.read(4+1+1)                   # Discard modification time,
                                        # extra flags, and OS byte.
    if flag & FEXTRA:
        # Read & discard the extra field, if present
        xlen = ord(input.read(1))
        xlen += 256*ord(input.read(1))
        input.read(xlen)
    if flag & FNAME:
        # Read and discard a null-terminated string containing the filename
        while True:
            s = input.read(1)
            if s == '\0': break
    if flag & FCOMMENT:
        # Read and discard a null-terminated string containing a comment
        while True:
            s=input.read(1)
            if s=='\0': break
    if flag & FHCRC:
        input.read(2)                   # Read & discard the 16-bit header CRC

decompobj = zlib.decompressobj(-zlib.MAX_WBITS)
    crcval = zlib.crc32("")
    length = 0
    while True:
        data=input.read(1024)
        if data == "":
            break
        decompdata = decompobj.decompress(data)
        output.write(decompdata)
        length += len(decompdata)
        crcval = zlib.crc32(decompdata, crcval)

decompdata = decompobj.flush()
    output.write(decompdata)
    length += len(decompdata)
    crcval = zlib.crc32(decompdata, crcval)

# 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.  The
    # decompressor is smart and knows when to stop, so feeding it
    # extra data is harmless.
    input.seek(-8, 2)
    crc32 = read32(input)
    isize = read32(input)
    if crc32 != crcval:
        print 'CRC check failed.'
    if isize != length:
        print 'Incorrect length of data produced'

def main():
    if len(sys.argv)!=2:
        print 'Usage: minigzip.py <filename>'
        print '  The file will be compressed or decompressed.'
        sys.exit(0)

filename = sys.argv[1]
    if filename.endswith('.gz'):
        compressing = False
        outputname = filename[:-3]
    else:
        compressing = True
        outputname = filename + '.gz'

input = open(filename, 'rb')
    output = open(outputname, 'wb')

if compressing:
        compress(filename, input, output)
    else:
        decompress(input, output)

input.close()
    output.close()

if __name__ == '__main__':
    main()

cmd: