Back to index

glibc  2.9
group_member.c
Go to the documentation of this file.
00001 /* `group_member' -- test if process is in a given group.
00002    Copyright (C) 1995, 1997, 2002 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <sys/types.h>
00021 #include <unistd.h>
00022 #include <stdlib.h>
00023 #include <limits.h>
00024 
00025 #ifndef NGROUPS_MAX
00026 #define NGROUPS_MAX  16     /* First guess.  */
00027 #endif
00028 
00029 int
00030 __group_member (gid)
00031      gid_t gid;
00032 {
00033   int n, size;
00034   gid_t *groups;
00035 
00036   size = NGROUPS_MAX;
00037   do
00038     {
00039       groups = __alloca (size * sizeof *groups);
00040       n = __getgroups (size, groups);
00041       size *= 2;
00042     } while (n == size / 2);
00043 
00044   while (n >= 0)
00045     if (groups[n--] == gid)
00046       return 1;
00047 
00048   return 0;
00049 }
00050 weak_alias (__group_member, group_member)