1 /* group-member.c -- determine whether group id is in calling user's group list
3 Copyright (C) 1994, 1997, 1998, 2003, 2005, 2006 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>
41 free_group_info (struct group_info const *g)
47 get_group_info (struct group_info *gi)
50 int n_group_slots = getgroups (0, NULL);
53 if (n_group_slots < 0)
56 /* Avoid xnmalloc, as it goes awry when SIZE_MAX < n_group_slots. */
57 if (xalloc_oversized (n_group_slots, sizeof *group))
59 group = xmalloc (n_group_slots * sizeof *group);
60 n_groups = getgroups (n_group_slots, group);
62 /* In case of error, the user loses. */
69 gi->n_groups = n_groups;
75 #endif /* not HAVE_GETGROUPS */
77 /* Return non-zero if GID is one that we have in our groups list.
78 If there is no getgroups function, return non-zero if GID matches
79 either of the current or effective group IDs. */
82 group_member (gid_t gid)
84 #ifndef HAVE_GETGROUPS
85 return ((gid == getgid ()) || (gid == getegid ()));
91 if (! get_group_info (&gi))
94 /* Search through the list looking for GID. */
96 for (i = 0; i < gi.n_groups; i++)
98 if (gid == gi.group[i])
105 free_group_info (&gi);
108 #endif /* HAVE_GETGROUPS */
116 main (int argc, char **argv)
120 program_name = argv[0];
122 for (i=1; i<argc; i++)
126 gid = atoi (argv[i]);
127 printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no");