1 /* group-member.c -- determine whether group id is in calling user's group list
3 Copyright (C) 1994, 1997-1998, 2003, 2005-2006, 2009-2010 Free Software
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
21 #include "group-member.h"
25 #include <sys/types.h>
39 free_group_info (struct group_info const *g)
45 get_group_info (struct group_info *gi)
48 int n_group_slots = getgroups (0, NULL);
51 if (n_group_slots < 0)
54 /* Avoid xnmalloc, as it goes awry when SIZE_MAX < n_group_slots. */
55 if (xalloc_oversized (n_group_slots, sizeof *group))
57 group = xmalloc (n_group_slots * sizeof *group);
58 n_groups = getgroups (n_group_slots, group);
60 /* In case of error, the user loses. */
67 gi->n_groups = n_groups;
73 /* Return non-zero if GID is one that we have in our groups list.
74 Note that the groups list is not guaranteed to contain the current
75 or effective group ID, so they should generally be checked
79 group_member (gid_t gid)
85 if (! get_group_info (&gi))
88 /* Search through the list looking for GID. */
90 for (i = 0; i < gi.n_groups; i++)
92 if (gid == gi.group[i])
99 free_group_info (&gi);
109 main (int argc, char **argv)
113 program_name = argv[0];
115 for (i = 1; i < argc; i++)
119 gid = atoi (argv[i]);
120 printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no");