uclibc-ng/libc/pwd_grp/initgroups.c

/* vi: set sw=4 ts=4: */
/*
 * initgroups.c - This file is part of the libc-8086/grp package for ELKS,
 * Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>.
 * Copyright (C) 2001-2003 Erik Andersen <andersee@debian.org>
 * 
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <paths.h>
#include <stdlib.h>
#include <errno.h>
#include "config.h"

#ifdef __UCLIBC_HAS_THREADS__
#include <pthread.h>
static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER;
# define LOCK   pthread_mutex_lock(&mylock)
# define UNLOCK pthread_mutex_unlock(&mylock);
#else
# define LOCK
# define UNLOCK
#endif

int initgroups(__const char *user, gid_t gid)
{
	gid_t *group_list = NULL;
	register char **tmp_mem;
	int num_groups;
	int grp_fd;
	static struct group group;
	static char line_buff[PWD_BUFFER_SIZE];

	if ((grp_fd = open(_PATH_GROUP, O_RDONLY)) < 0)
		return errno;

	num_groups = 0;
	group_list = (gid_t *) realloc(group_list, 1);
	group_list[num_groups] = gid;
	LOCK;
	while (__getgrent_r(&group, line_buff, sizeof(line_buff), grp_fd) == 0)
	{
		if (group.gr_gid != gid)
		{
			tmp_mem = group.gr_mem;
			while (*tmp_mem != NULL) {
				if (!strcmp(*tmp_mem, user)) {
					num_groups++;
					group_list = (gid_t *) realloc(group_list, num_groups * sizeof(gid_t *));
					group_list[num_groups-1] = group.gr_gid;
				}
				tmp_mem++;
			}
		}
	}
	close(grp_fd);
	UNLOCK;
	return setgroups(num_groups, group_list);
}