/*-
 * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Berkeley Software Design Inc's name may not be used to endorse or
 *    promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/usr.sbin/daemon/daemon.c 231909 2012-02-19 10:20:37Z trociny $");

#include <sys/param.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <pwd.h>
#include <libutil.h>
#include <login_cap.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static void restrict_process(const char *);
static void wait_child(pid_t pid);
static void usage(void);

int
main(int argc, char *argv[])
{
	struct pidfh *pfh = NULL;
	int ch, nochdir, noclose;
	const char *pidfile, *user;
	pid_t otherpid, pid;

	nochdir = noclose = 1;
	pidfile = user = NULL;
	while ((ch = getopt(argc, argv, "-cfp:u:")) != -1) {
		switch (ch) {
		case 'c':
			nochdir = 0;
			break;
		case 'f':
			noclose = 0;
			break;
		case 'p':
			pidfile = optarg;
			break;
		case 'u':
			user = optarg;
			break;
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc == 0)
		usage();

	pfh = NULL;
	/*
	 * Try to open the pidfile before calling daemon(3),
	 * to be able to report the error intelligently
	 */
	if (pidfile != NULL) {
		pfh = pidfile_open(pidfile, 0600, &otherpid);
		if (pfh == NULL) {
			if (errno == EEXIST) {
				errx(3, "process already running, pid: %d",
				    otherpid);
			}
			err(2, "pidfile ``%s''", pidfile);
		}
	}

	if (daemon(nochdir, noclose) == -1)
		err(1, NULL);

	pid = 0;
	if (pidfile != NULL) {
		/*
		 * Spawn a child to exec the command, so in the parent
		 * we could wait for it to exit and remove pidfile.
		 */
		pid = fork();
		if (pid == -1) {
			pidfile_remove(pfh);
			err(1, "fork");
		}
	}
	if (pid == 0) {
		/* Now that we are the child, write out the pid. */
		pidfile_write(pfh);

		if (user != NULL)
			restrict_process(user);

		execvp(argv[0], argv);

		/*
		 * execvp() failed -- report the error. The child is
		 * now running, so the exit status doesn't matter.
		 */
		err(1, "%s", argv[0]);
	}
	setproctitle("%s[%d]", argv[0], pid);
	wait_child(pid);
	pidfile_remove(pfh);
	exit(0); /* Exit status does not matter. */
}

static void
restrict_process(const char *user)
{
	struct passwd *pw = NULL;

	pw = getpwnam(user);
	if (pw == NULL)
		errx(1, "unknown user: %s", user);

	if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
		errx(1, "failed to set user environment");
}

static void
wait_child(pid_t pid)
{
	int status;

	while (waitpid(pid, &status, 0) == -1) {
		if (errno != EINTR) {
			warn("waitpid");
			break;
		}
	}
}

static void
usage(void)
{
	(void)fprintf(stderr,
	    "usage: daemon [-cf] [-p pidfile] [-u user] command "
		"arguments ...\n");
	exit(1);
}