Split Binary File on Zero'd Memory Regions

binary-split-zero.py

#!/usr/bin/env python

# The idea behind this file is that many times firmware images are constructed with zero'd out address regions as the delimiter.
# This script will split files in a firmware image when the embedded files are $MAX zero'd bytes in distance from each other.

import sys
import copy

FILE=sys.argv[1]
MAX=512

print ("Analyzing File: " + FILE)

with open(FILE) as f:
    counter = 0
    data = f.read()
    start = 0
    tripped = False
    for byte in range(len(data)):
        if data[byte] == '\x00':
            if not tripped:
                counter = counter + 1
                if counter == MAX:
                    tripped = True
                    with open('splitter-%08d-%08d.bin' % (start, byte - start - MAX), 'w') as wf:
                        wf.write(data[start:(byte - MAX)])
                        wf.close()
                        print('wrote file. start: %08d. length was %08d' % (start, byte - start - MAX))
                        start = byte + 1
                        counter = 0
            else:
                start = byte + 1
        else:
            tripped = False
            counter = 0
    f.close()