tw-crc32sum

#!/usr/bin/env python

from binascii import crc32

def crc32tw(data, crc=0):
	return crc32(data, crc)


def _file_bin_chunks(file, count=2**15):
	return iter((lambda:file.read(count)), b'')

if __name__ == '__main__':
	try:
		import argparse
		import sys

		p = argparse.ArgumentParser(description="Print Teeworlds' CRC checksums.")
		p.add_argument('filenames', metavar="FILE", type=str, nargs='*', help="With no FILE, or when FILE is -, read standard input.")
		p.add_argument('-q', '--quiet', help="Quiet mode, only output the CRC checksums, omit filenames", action='store_true')
		args = p.parse_args()
		for filename in args.filenames or ('-'):
			crc = crc32tw(b'')
			_filename = filename
			if filename == '-':
				_filename = 0
			try:
				with open(_filename, 'rb') as f:
					for chunk in _file_bin_chunks(f):
						crc = crc32tw(chunk, crc)
			except FileNotFoundError:
				sys.stderr.write("{}: {}: No such file or directory\n".format(p.prog, filename))
			except IsADirectoryError:
				sys.stderr.write("{}: {}: Is a directory\n".format(p.prog, filename))
			except PermissionError:
				sys.stderr.write("{}: {}: Permission denied\n".format(p.prog, filename))
			else:
				if not args.quiet:
					print("{:08x} {}".format(crc, filename))
				else:
					print("{:08x}".format(crc))
	except KeyboardInterrupt as e:
		print()