Hurd: Fix setres[ug]id handling of -1

1 files changed, 61 insertions, 15 deletions

diff --git a/sysdeps/mach/hurd/setresgid.c b/sysdeps/mach/hurd/setresgid.c
index 9d5885beda..eebd364fc6 100644
--- a/sysdeps/mach/hurd/setresgid.c
+++ b/sysdeps/mach/hurd/setresgid.c
@@ -1,5 +1,5 @@
 /* setresgid -- set real group ID, effective group ID, and saved-set group ID
-   Copyright (C) 2002, 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2002-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -28,7 +28,6 @@ __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
 {
   auth_t newauth;
   error_t err;
-  gid_t agids[2] = { rgid, sgid };
 
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
@@ -37,31 +36,78 @@ __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
   if (!err)
     {
       /* Make a new auth handle which has EGID as the first element in the
-         list of effective gids.  */
+	 list of effective gids.  */
 
-      if (_hurd_id.gen.ngids > 0)
+      uid_t *newgen, *newaux;
+      uid_t auxs[2] = { rgid, sgid };
+      size_t ngen, naux;
+
+      newgen = _hurd_id.gen.gids;
+      ngen = _hurd_id.gen.ngids;
+      if (egid != -1)
+	{
+	  if (_hurd_id.gen.ngids == 0)
+	    {
+	      /* No effective gids now.  The new set will be just UID.  */
+	      newgen = &egid;
+	      ngen = 1;
+	    }
+	  else
+	    {
+	      _hurd_id.gen.gids[0] = egid;
+	      _hurd_id.valid = 0;
+	    }
+	}
+
+      newaux = _hurd_id.aux.gids;
+      naux = _hurd_id.aux.ngids;
+      if (rgid != -1)
 	{
-	  _hurd_id.gen.gids[0] = egid;
-	  _hurd_id.valid = 0;
+	  if (_hurd_id.aux.ngids == 0)
+	    {
+	      newaux = &rgid;
+	      naux = 1;
+	    }
+	  else
+	    {
+	      _hurd_id.aux.gids[0] = rgid;
+	      _hurd_id.valid = 0;
+	    }
 	}
-      if (_hurd_id.aux.ngids > 1)
+
+      if (sgid != -1)
 	{
-	  _hurd_id.aux.gids[0] = rgid;
-	  _hurd_id.aux.gids[1] = sgid;
-	  _hurd_id.valid = 0;
+	  if (rgid == -1)
+	    {
+	      if (_hurd_id.aux.ngids >= 1)
+		auxs[0] = _hurd_id.aux.gids[0];
+	      else if (_hurd_id.gen.ngids >= 1)
+		auxs[0] = _hurd_id.gen.gids[0];
+	      else
+		/* Not even an effective GID.
+                   Fall back to the only GID we have. */
+		auxs[0] = sgid;
+	    }
+	  if (_hurd_id.aux.ngids <= 1)
+	    {
+	      /* No saved gids now.  The new set will be just UID.  */
+	      newaux = auxs;
+	      naux = 2;
+	    }
+	  else
+	    {
+	      _hurd_id.aux.gids[1] = sgid;
+	      _hurd_id.valid = 0;
+	    }
 	}
 
       err = __USEPORT (AUTH, __auth_makeauth
 		       (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
 			_hurd_id.gen.uids, _hurd_id.gen.nuids,
 			_hurd_id.aux.uids, _hurd_id.aux.nuids,
-			_hurd_id.gen.ngids ? _hurd_id.gen.gids : &egid,
-			_hurd_id.gen.ngids ?: 1,
-			_hurd_id.aux.ngids > 1 ? _hurd_id.aux.gids : agids,
-			_hurd_id.aux.ngids > 1 ? _hurd_id.aux.ngids : 2,
+			newgen, ngen, newaux, naux,
 			&newauth));
     }
-
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;