import ctypes
import mmap
import os
import tempfile

def killctypes():
    fd, name = tempfile.mkstemp()
    os.write(fd, '\x00' * mmap.PAGESIZE)

    m = mmap.mmap(fd, mmap.PAGESIZE, mmap.MAP_SHARED, mmap.PROT_WRITE)
    m.resize(mmap.PAGESIZE * 2)

    killer_t = ctypes.c_char * (mmap.PAGESIZE + 1)
    killer = killer_t.from_buffer(m, 0)
    killer.value = 'x' * (mmap.PAGESIZE + 1)
    print killer.value
    m.resize(mmap.PAGESIZE * 3)
    print repr(m[0])
    print killer.value


if __name__ == '__main__':
    killctypes()