/*
 *  swrap by Davide Libenzi (secure exec wrapper)
 *  Copyright (C) 2003..2010  Davide Libenzi
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>


static void usage(char *prg)
{
	fprintf(stderr, "%s {-u UID, -U UNAME} {-g GID, -G GNAME} CMD [PARAM ...]\n", prg);
	exit(1);
}

int main(int ac, char **av)
{
	int i;
	uid_t uid = (uid_t) -1;
	gid_t gid = (gid_t) -1;
	char const *uname = NULL, *gname = NULL;

	while ((i = getopt(ac, av, "+u:U:g:G:h")) != EOF) {
		switch (i) {
		case 'u':
			uid = atoi(optarg);
			break;
		case 'U':
			uname = optarg;
			break;
		case 'g':
			gid = atoi(optarg);
			break;
		case 'G':
			gname = optarg;
			break;
		case 'h':
			usage(av[0]);
		}
	}
	if (uname != NULL) {
		struct passwd *pwn;

		if ((pwn = getpwnam(uname)) == NULL) {
			perror(uname);
			return 2;
		}
		uid = pwn->pw_uid;
	}
	if (gname != NULL) {
		struct group *grn;

		if ((grn = getgrnam(gname)) == NULL) {
			perror(gname);
			return 3;
		}
		gid = grn->gr_gid;
	}
	if (uid == (uid_t) -1 || gid == (gid_t) -1 || optind >= ac)
		usage(av[0]);


	if (setgid(gid)) {
		perror("Setting group");
		return 4;
	}
	if (setuid(uid)) {
		perror("Setting user");
		return 5;
	}

	execvp(av[optind], &av[optind]);
	perror(av[optind]);

	return 6;
}