zigg/journal

Wednesday, April 15, 2009

Ubuntu's missing crc32sum tool, in Python

Did I hear you say "I want a crc32sum application for Linux that can not only output CRC32 sums for a list of files, but also handle stdin if I leave its argument list blank, and I don't mind if it's hackish, so long as it works?"
#!/usr/bin/env python
#
#       A CRC32 summing utility that functions mostly like md5sum or
#       sha1sum.
#
#       Public domain by Matt Behrens <matt@zigg.com> with NO WARRANTY.
#
#       Usage: crc32sum [<filename> [<filename>...]]
#

BLOCKSIZE = 0x10000

import sys
from zlib import crc32

if sys.argv[1:]:
      names = sys.argv[1:]
else:
      names = [None]

for name in names:
      if name is not None:
              f = open(name, 'rb')
      else:
              f = sys.stdin
              name = '-'

      crc = None
      while 1:
              data = f.read(BLOCKSIZE)
              if data:
                      if crc is None:
                              crc = crc32(data)
                      else:
                              crc = crc32(data, crc)
              else:
                      break

      print '%08x\t%s' % ((crc & 0xffffffff), name)
Don't say I've never done anything for you.

Labels:

posted by zigg 10:24 PM

0 Comments:

Further comments are disabled indefinitely. Here's why.