#!/usr/bin/env python
import mmap
import os
from random import randint
import sys
RANGE_START = 0x1b30
RANGE_END = 0x1b50
MIN_BYTES_TO_FLIP = 1
MAX_BYTES_TO_FLIP = 5
with open(sys.argv[1], "r+b") as f:
mapped = mmap.mmap(f.fileno(), 0)
bytes_to_flip = randint(MIN_BYTES_TO_FLIP, MAX_BYTES_TO_FLIP)
bytes_flipped = 0
while bytes_flipped < bytes_to_flip:
byte_pos = randint(RANGE_START, RANGE_END)
byte_new = chr(randint(0, 255))
mapped[byte_pos] = byte_new
bytes_flipped += 1
mapped.close()