Look before you leap

There are countless reasons to do unsafe memory access.  Here's some help:

import ctypes

import os

if hasattr(ctypes.cdll, "msvcrt"):  #windows branch

    _BUF = ctypes.create_string_buffer('a')

    def _check(address):

        try:

            ctypes.cdll.msvcrt.memcpy(_BUF, address, 1)

            return True

        except WindowsError:

            return False

else:

    libc = ctypes.CDLL('libc.so.6')

    libc.write.argtypes = ctypes.c_int, ctypes.c_void_p, ctypes.c_size_t

    _BUF = open('/tmp/_buf', 'w')

    _FD = _BUF.fileno()

    os.unlink(_BUF)

    def _check(address):

        rc = libc.write(_FD, address, 1)

        _BUF.seek(0)

        return rc == 1

def is_valid_ptr(address):

    'determines if the passed address (integer) is a valid pointer'

    return _check(address)