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145 lines
3.0 KiB
C
145 lines
3.0 KiB
C
/* group-member.c -- determine whether group id is in calling user's group list
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Copyright (C) 1994, 1997, 1998, 2003 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "group-member.h"
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#include <stdio.h>
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#include <sys/types.h>
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#include <stdlib.h>
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#include "xalloc.h"
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struct group_info
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{
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int n_groups;
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GETGROUPS_T *group;
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};
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#if HAVE_GETGROUPS
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static void
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free_group_info (struct group_info *g)
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{
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free (g->group);
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free (g);
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}
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static struct group_info *
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get_group_info (void)
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{
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int n_groups;
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int n_group_slots;
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struct group_info *gi;
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GETGROUPS_T *group;
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/* getgroups () returns the number of elements that it was able to
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place into the array. We simply continue to call getgroups ()
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until the number of elements placed into the array is smaller than
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the physical size of the array. */
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group = NULL;
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n_groups = 0;
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n_group_slots = 0;
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while (n_groups == n_group_slots)
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{
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n_group_slots += 64;
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group = xrealloc (group, n_group_slots * sizeof (GETGROUPS_T));
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n_groups = getgroups (n_group_slots, group);
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}
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/* In case of error, the user loses. */
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if (n_groups < 0)
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{
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free (group);
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return NULL;
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}
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gi = xmalloc (sizeof (*gi));
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gi->n_groups = n_groups;
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gi->group = group;
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return gi;
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}
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#endif /* not HAVE_GETGROUPS */
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/* Return non-zero if GID is one that we have in our groups list.
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If there is no getgroups function, return non-zero if GID matches
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either of the current or effective group IDs. */
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int
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group_member (gid_t gid)
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{
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#ifndef HAVE_GETGROUPS
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return ((gid == getgid ()) || (gid == getegid ()));
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#else
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int i;
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int found;
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struct group_info *gi;
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gi = get_group_info ();
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if (gi == NULL)
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return 0;
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/* Search through the list looking for GID. */
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found = 0;
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for (i = 0; i < gi->n_groups; i++)
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{
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if (gid == gi->group[i])
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{
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found = 1;
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break;
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}
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}
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free_group_info (gi);
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return found;
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#endif /* HAVE_GETGROUPS */
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}
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#ifdef TEST
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char *program_name;
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int
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main (int argc, char **argv)
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{
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int i;
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program_name = argv[0];
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for (i=1; i<argc; i++)
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{
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gid_t gid;
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gid = atoi (argv[i]);
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printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no");
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}
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exit (0);
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}
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#endif /* TEST */
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