1: /* `group_member' -- test if process is in a given group.
    2:    Copyright (C) 1995, 1997, 2002 Free Software Foundation, Inc.
    3:    This file is part of the GNU C Library.
    4: 
    5:    The GNU C Library is free software; you can redistribute it and/or
    6:    modify it under the terms of the GNU Lesser General Public
    7:    License as published by the Free Software Foundation; either
    8:    version 2.1 of the License, or (at your option) any later version.
    9: 
   10:    The GNU C Library is distributed in the hope that it will be useful,
   11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13:    Lesser General Public License for more details.
   14: 
   15:    You should have received a copy of the GNU Lesser General Public
   16:    License along with the GNU C Library; if not, write to the Free
   17:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   18:    02111-1307 USA.  */
   19: 
   20: #include <sys/types.h>
   21: #include <unistd.h>
   22: #include <stdlib.h>
   23: #include <limits.h>
   24: 
   25: #ifndef NGROUPS_MAX
   26: #define NGROUPS_MAX     16  /* First guess.  */
   27: #endif
   28: 
   29: int
   30: __group_member (gid)
   31:      gid_t gid;
   32: {
   33:   int n, size;
   34:   gid_t *groups;
   35: 
   36:   size = NGROUPS_MAX;
   37:   do
   38:     {
   39:       groups = __alloca (size * sizeof *groups);
   40:       n = __getgroups (size, groups);
   41:       size *= 2;
   42:     } while (n == size / 2);
   43: 
   44:   while (n >= 0)
   45:     if (groups[n--] == gid)
   46:       return 1;
   47: 
   48:   return 0;
   49: }
   50: weak_alias (__group_member, group_member)