bug#12621: Emacs 24.1 crashing on Win7

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 13 Dec 2012 10:22:42 +0000 (GMT)
> From: Arunas Ruksnaitis <aris020@yahoo.co.uk>
> 
> Just to confirm, this is a big problem for me, too.
> My observations confirm the original report.
> Stack trace, should it help, is here. I guess "lookup_account_sid" is passing an invalid lpSid?

No, I don't think the Sid can be invalid, because it is validated just
before the call that crashes, by calling IsValidSid:

  if (what == UID)
    result = get_security_descriptor_owner (psd, &sid, &dflt);
  else if (what == GID)
    result = get_security_descriptor_group (psd, &sid, &dflt);
  else
    result = 0;

  if (!result || !is_valid_sid (sid))  <<<<<<<<<<<<<<<<<<<<<<<<<<<
    use_dflt = 1;
  else if (!w32_cached_id (sid, id, nm))
    {
      /* If FNAME is a UNC, we need to lookup account on the
	 specified machine.  */
      if (IS_DIRECTORY_SEP (fname[0]) && IS_DIRECTORY_SEP (fname[1])
	  && fname[2] != '\0')
	{
	  const char *s;
	  char *p;

	  for (s = fname + 2, p = machine;
	       *s && !IS_DIRECTORY_SEP (*s); s++, p++)
	    *p = *s;
	  *p = '\0';
	  mp = machine;
	}

      if (!lookup_account_sid (mp, sid, name, &name_len,
			       domain, &domain_len, &ignore)
	  || name_len > UNLEN+1)

I actually suspect that the problem might be in the server name, the
first argument to lookup_account_sid.  If you can easily reproduce
this under GDB, can you show what is the value of 'fname' and of
'machine' in the above snippet?