SFV sum

gistfile1.py

#!/usr/bin/env python3

import sys, os
import zlib

ChunkSize = 1024*1024

def crcFile(f):
    Chunk = f.read(ChunkSize)
    CRC = 0
    while Chunk:
        CRC = zlib.crc32(Chunk, CRC)
        Chunk = f.read(ChunkSize)

    return CRC & 0xffffffff

def checkSFV(sfv_name):
    """Returns a generator of (filename, passed) in which `passed' is
    a bool.
    """
    import re
    SFV = open(sfv_name, 'r')
    # Result = []
    for Line in SFV:
        Match = re.match('(.*)[ \t]+([0-9a-f]+)', Line.strip())
        Filename = Match.group(1)
        Sum = int(Match.group(2), 16)
        with open(Filename, 'rb') as File:
            # Result.append((Filename, Sum == crcFile(File)))
            yield (Filename, Sum == crcFile(File))

    SFV.close()
    # return Result

def main(argv):
    import argparse

    Parser = argparse.ArgumentParser(description='SFV checksum-mer.')
    Parser.add_argument('Files', metavar='FILE', type=str, nargs='*',
                        help='SFV File(s) to checksum, or file(s) to check to generate a SFV.')
    Parser.add_argument('-p', '--progress', dest='ShowProg', action='store_true',
                        help='Which each file checked, prints a "." to stderr.  Only works with "-g".')
    Parser.add_argument('-g', '--generate', dest='GenSFV', action='store_true',
                        help="If issued, generate a SFV file from FILEs to stdout, "
                        "instead of treating FILEs as SFVs.")

    Args = Parser.parse_args(argv[1:])

    if Args.GenSFV == False and len(Args.Files) == 0:
        print("{:08x}".format(crcFile(sys.stdin.buffer)))

    if Args.GenSFV:
        if Args.Files:
            for FName in Args.Files:
                with open(FName, 'rb') as File:
                    print(FName, "{:08x}".format(crcFile(File)))
                if Args.ShowProg:
                    sys.stderr.write('.')
                    sys.stderr.flush()
            if Args.ShowProg:
                sys.stderr.write('\n')
        else:
            print("Need filenames... :-(", file=sys.stderr)
            return -1
        
    else:
        Results = []
        Fails = []
        for SFVName in Args.Files:
            for Result in checkSFV(SFVName):
                if Result[1] == True:
                    print("PASSED ---", Result[0])
                else:
                    print("FAILED ---", Result[0])
                    Fails.append(Result)
            
        if Fails:
            print()
            print("Fails:")
            for Fail in Fails:
                print(Fail[0])
        else:
            print("All passed.")
            
    return 0

if __name__ == "__main__":
    sys.exit(main(sys.argv))