[PATCH,HURD]: Fix setres[ug]id handling of -1

[Samuel Thibault]

Hello,

When passed -1, setres[ug]id are supposed not to change the existing
value.  The patch below does this the same way as setre[ug]id.

Samuel

2011-10-17  Samuel Thibault  <samuel.thibault@ens-lyon.org>

* sysdeps/mach/hurd/setresgid.c (__setresgid): Handle the -1 case, which
shall preserve existing values.
* sysdeps/mach/hurd/setresuid.c (__setresuid): Likewise.

diff --git a/sysdeps/mach/hurd/setresgid.c b/sysdeps/mach/hurd/setresgid.c
index 8fcf26e..2a0dd90 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, 2005, 2006, 2011 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
@@ -29,7 +29,6 @@ __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);
@@ -40,29 +39,75 @@ __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
       /* Make a new auth handle which has EGID as the first element in the
          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, fallback to the only UID 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;
 
diff --git a/sysdeps/mach/hurd/setresuid.c b/sysdeps/mach/hurd/setresuid.c
index ccf8d08..e254437 100644
--- a/sysdeps/mach/hurd/setresuid.c
+++ b/sysdeps/mach/hurd/setresuid.c
@@ -1,5 +1,5 @@
 /* setresuid -- set real user ID, effective user ID, and saved-set user ID
-   Copyright (C) 2002, 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2005, 2006, 2011 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
@@ -29,7 +29,6 @@ __setresuid (uid_t ruid, uid_t euid, uid_t suid)
 {
   auth_t newauth;
   error_t err;
-  uid_t auids[2] = { ruid, suid };
 
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
@@ -40,29 +39,75 @@ __setresuid (uid_t ruid, uid_t euid, uid_t suid)
       /* Make a new auth handle which has EUID as the first element in the
          list of effective uids.  */
 
-      if (_hurd_id.gen.nuids > 0)
+      uid_t *newgen, *newaux;
+      uid_t auxs[2] = { ruid, suid };
+      size_t ngen, naux;
+
+      newgen = _hurd_id.gen.uids;
+      ngen = _hurd_id.gen.nuids;
+      if (euid != -1)
+       {
+         if (_hurd_id.gen.nuids == 0)
+           {
+             /* No effective uids now.  The new set will be just UID.  */
+             newgen = &euid;
+             ngen = 1;
+           }
+         else
+           {
+             _hurd_id.gen.uids[0] = euid;
+             _hurd_id.valid = 0;
+           }
+       }
+
+      newaux = _hurd_id.aux.uids;
+      naux = _hurd_id.aux.nuids;
+      if (ruid != -1)
        {
-         _hurd_id.gen.uids[0] = euid;
-         _hurd_id.valid = 0;
+         if (_hurd_id.aux.nuids == 0)
+           {
+             newaux = &ruid;
+             naux = 1;
+           }
+         else
+           {
+             _hurd_id.aux.uids[0] = ruid;
+             _hurd_id.valid = 0;
+           }
        }
-      if (_hurd_id.aux.nuids > 1)
+
+      if (suid != -1)
        {
-         _hurd_id.aux.uids[0] = ruid;
-         _hurd_id.aux.uids[1] = suid;
-         _hurd_id.valid = 0;
+         if (ruid == -1)
+           {
+             if (_hurd_id.aux.nuids >= 1)
+               auxs[0] = _hurd_id.aux.uids[0];
+             else if (_hurd_id.gen.nuids >= 1)
+               auxs[0] = _hurd_id.gen.uids[0];
+             else
+               /* Not even an effective uid, fallback to the only UID we have. 
*/
+               auxs[0] = suid;
+           }
+         if (_hurd_id.aux.nuids <= 1)
+           {
+             /* No saved uids now.  The new set will be just UID.  */
+             newaux = auxs;
+             naux = 2;
+           }
+         else
+           {
+             _hurd_id.aux.uids[1] = suid;
+             _hurd_id.valid = 0;
+           }
        }
 
       err = __USEPORT (AUTH, __auth_makeauth
                       (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
-                       _hurd_id.gen.nuids ? _hurd_id.gen.uids : &euid,
-                       _hurd_id.gen.nuids ?: 1,
-                       _hurd_id.aux.nuids > 1 ? _hurd_id.aux.uids : auids,
-                       _hurd_id.aux.nuids > 1 ? _hurd_id.aux.nuids : 2,
+                       newgen, ngen, newaux, naux,
                        _hurd_id.gen.gids, _hurd_id.gen.ngids,
                        _hurd_id.aux.gids, _hurd_id.aux.ngids,
                        &newauth));
     }
-
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;