Python implementation of streaming Adler32 checksum

adler32.py

#!/usr/bin/env python
import io,sys,zlib

for filename in sys.argv[1:]:
	try:
		file = io.open(filename,'rb')
		buf = bytearray(1024*128)
		part_sum = 1;
		while True:
			n = file.readinto(buf)
			if n == 0:
				break
			part_sum = zlib.adler32(bytes(buf)[0:n], part_sum)
		print ("%08X  %s" % (part_sum & 0xFFFFFFFF, filename))
	except IOError as e:
		sys.stderr.write('%s: %s: %s\n' % (sys.argv[0], filename, e))