[PATCH] Cygwin: Allow to set SO_PEERCRED zero (v2)

[Corinna Vinschen]

On Dec  7 02:29, Mark Geisert wrote:
> The existing code errors as EINVAL any attempt to set a value for
> SO_PEERCRED via setsockopt() on an AF_UNIX/AF_LOCAL socket.  But to
> enable the workaround set_no_getpeereid behavior for Python one has
> to be able to set SO_PEERCRED to zero.  Ergo, this patch.  Python has
> no way to specify a NULL pointer for 'optval'.
> 
> This v2 of patch allows the original working (i.e., allow NULL,0 for
> optval,optlen to mean turn off SO_PEERCRED) in addition to the new
> working described above.  The sense of the 'if' stmt is reversed for
> readability.
> 
> ---
>  winsup/cygwin/fhandler_socket_local.cc | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/winsup/cygwin/fhandler_socket_local.cc b/winsup/cygwin/fhandler_socket_local.cc
> index c94bf828f..964f3e819 100644
> --- a/winsup/cygwin/fhandler_socket_local.cc
> +++ b/winsup/cygwin/fhandler_socket_local.cc
> @@ -1430,10 +1430,14 @@ fhandler_socket_local::setsockopt (int level, int optname, const void *optval,
>  	     FIXME: In the long run we should find a more generic solution
>  	     which doesn't require a blocking handshake in accept/connect
>  	     to exchange SO_PEERCRED credentials. */
> -	  if (optval || optlen)
> -	    set_errno (EINVAL);
> -	  else
> +	  /* Temporary: Allow SO_PEERCRED to only be zeroed. Two ways to
> +	     accomplish this: pass NULL,0 for optval,optlen; or pass the
> +	     address,length of an '(int) 0' set up by the caller. */
> +	  if ((!optval && !optlen) ||
> +		(optlen == (socklen_t) sizeof (int) && !*(int *) optval))
>  	    ret = af_local_set_no_getpeereid ();
> +	  else
> +	    set_errno (EINVAL);
>  	  return ret;
>  
>  	case SO_REUSEADDR:
> -- 
> 2.29.2

Pushed


Thanks,
Corinna