1/* `group_member' -- test if process is in a given group.
2 Copyright (C) 1995-2022 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, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <sys/types.h>
20#include <unistd.h>
21#include <stdlib.h>
22#include <limits.h>
23
24#ifndef NGROUPS_MAX
25#define NGROUPS_MAX 16 /* First guess. */
26#endif
27
28int
29__group_member (gid_t gid)
30{
31 int n, size;
32 gid_t *groups;
33
34 size = NGROUPS_MAX;
35 do
36 {
37 groups = __alloca (size * sizeof *groups);
38 n = __getgroups (size, groups);
39 size *= 2;
40 }
41 while (n == size / 2);
42
43 while (n-- > 0)
44 if (groups[n] == gid)
45 return 1;
46
47 return 0;
48}
49weak_alias (__group_member, group_member)
50