1  /* Copyright (C) 1993-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <unistd.h>
      20  #include <hurd.h>
      21  #include <hurd/id.h>
      22  #include <string.h>
      23  
      24  int
      25  __getgroups (int n, gid_t *gidset)
      26  {
      27    error_t err;
      28    int ngids;
      29    void *crit;
      30  
      31    if (n < 0)
      32      return __hurd_fail (EINVAL);
      33  
      34  retry:
      35    crit = _hurd_critical_section_lock ();
      36    __mutex_lock (&_hurd_id.lock);
      37  
      38    if (err = _hurd_check_ids ())
      39      {
      40        __mutex_unlock (&_hurd_id.lock);
      41        _hurd_critical_section_unlock (crit);
      42        if (err == EINTR)
      43  	/* Got a signal while inside an RPC of the critical section, retry again */
      44  	goto retry;
      45        return __hurd_fail (err);
      46      }
      47  
      48    ngids = _hurd_id.gen.ngids;
      49  
      50    if (n != 0)
      51      {
      52        /* Copy the gids onto stack storage and then release the idlock.  */
      53        gid_t gids[ngids];
      54        memcpy (gids, _hurd_id.gen.gids, sizeof (gids));
      55        __mutex_unlock (&_hurd_id.lock);
      56        _hurd_critical_section_unlock (crit);
      57  
      58        /* Now that the lock is released, we can safely copy the
      59  	 group set into the user's array, which might fault.  */
      60        if (ngids > n)
      61  	return __hurd_fail (EINVAL);
      62        memcpy (gidset, gids, ngids * sizeof (gid_t));
      63      }
      64    else
      65      {
      66        __mutex_unlock (&_hurd_id.lock);
      67        _hurd_critical_section_unlock (crit);
      68      }
      69  
      70    return ngids;
      71  }
      72  
      73  weak_alias (__getgroups, getgroups)