splitbyte.py [1.1]

#!/usr/bin/env python

"""splits a file at a given delimiter"""

__author__ = "S0lll0s"
__copyright__ = "Sol Bekic, 2013"
__license__ = "GPL"
__version__ = "1.1.0"

import sys

def splitbyte( file, pattern, verbose=False ):
 check = 0
 while 1:
  byte = file.read( len( pattern ) )

  if verbose: print "checking", byte
  if byte == '':
   if verbose: print 'Nothing found'
   break

  if check > 0: # we need to check the next 'check' bytes
   if pattern[-check:] in byte[ :check ]: # we found the rest
    file.seek( -len( pattern ) + check, 1 ) # rewind to the end of the match
    break

  if pattern in byte: # "full" match, we're at the end of the match already
   break

  check = 0
  for offset in range( 1, len( pattern ) ):
   if pattern[:-offset] in byte:
    if verbose: print "found with offset", offset
    check = offset
    break

 if verbose: print "found: "
 return file.read()

if __name__ == "__main__":
 import argparse

 parser = argparse.ArgumentParser( description='split files at a given delimiter' )

 parser.add_argument( "file", help='the file to search in' )
 parser.add_argument( "delimiter", help='delimiter, in hex notation' )
 parser.add_argument( "-v", "--verbose", action='store_true', help='verbose output' )
 parser.add_argument( "-d", "--direct", action='store_true', help='directly use the delimiter (no hex)' )

 args = parser.parse_args()

 file = open( args.file, 'r' )
 pattern = ( args.delimiter if args.direct else str( bytearray.fromhex( args.delimiter ) ) )

 if args.verbose: print "Pattern: ", ' '.join( hex( ord( x ) )[2:] for x in pattern )
 print splitbyte( file, pattern, args.verbose )