/* 

 *  daemon.c : Handle daemon initialization

 *  Copyright (C) 1996 Thomas Koenig

 *

 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <stdio.h>

#include <stdlib.h>

#ifdef HAVE_STDARG_H

#include <stdarg.h>

#endif

#include <sys/types.h>

#include <sys/stat.h>

#include <signal.h>

#include <fcntl.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef HAVE_SYSLOG_H

#include <syslog.h>

#endif

#ifdef HAVE_ERRNO_H

#include <errno.h>

#endif

#include "daemon.h"

#include "privs.h"

int daemon_debug = 0;

int daemon_foreground = 0;

static int

lock_fd(int fd)

{

    struct flock lock;

    lock.l_type = F_WRLCK;

    lock.l_whence = SEEK_SET;

    lock.l_start = 0;

    lock.l_len = 0;

    return fcntl(fd, F_SETLK, &lock);

}

void

perr(const char *fmt,...)

{

    char buf[1024];

    va_list args;

    va_start(args, fmt);

    vsnprintf(buf, sizeof(buf), fmt, args);

    va_end(args);

    if (daemon_debug) {

	perror(buf);

    } else

	syslog(LOG_ERR, "%s: %m", buf);

    exit(EXIT_FAILURE);

}

void

lerr(const char *fmt,...)

{

    char buf[1024];

    va_list args;

    va_start(args, fmt);

    vsnprintf(buf, sizeof(buf), fmt, args);

    va_end(args);

    if (daemon_debug) {

	perror(buf);

    } else

	syslog(LOG_ERR, "%s: %m", buf);

}

void

pabort(const char *fmt,...)

{

    char buf[1024];

    va_list args;

    va_start(args, fmt);

    vsnprintf(buf, sizeof(buf), fmt, args);

    va_end(args);

    if (daemon_debug) {

	fprintf(stderr, "%s\n", buf);

    } else

	syslog(LOG_ERR, "%s", buf);

    exit(EXIT_FAILURE);

}

void

daemon_setup()

{

    /* Set up standard daemon environment */

    pid_t pid;

    mode_t old_umask;

    int fd;

    FILE *fp;

    if (!daemon_debug) {

	close(0);

	close(1);

	close(2);

	if ((open("/dev/null", O_RDWR) != 0) ||

	    (open("/dev/null", O_RDWR) != 1) ||

	    (open("/dev/null", O_RDWR) != 2)) {

	    perr("Error redirecting I/O");

	}

    }

    if (daemon_foreground)

	pid = getpid();

    else {

	pid = fork();

	if (pid == -1) {

	    perr("Cannot fork");

	} else if (pid != 0) {

	    exit(0);

	}

	(void) setsid();

    }

    old_umask = umask(S_IWGRP | S_IWOTH);

    PRIV_START

    fd = open(PIDFILE, O_RDWR | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);

    if (fd == -1) {

	if (errno != EEXIST)

	    perr("Cannot open " PIDFILE);

	if ((fd = open(PIDFILE, O_RDWR)) < 0)

	    perr("Cannot open " PIDFILE);

	fp = fdopen(fd, "rw");

	if (fp == NULL) {

	    perr("Cannot open " PIDFILE " for reading");

	}

	pid = -1;

	if ((fscanf(fp, "%d", &pid) != 1) || (pid == getpid())

	    || (lock_fd(fileno(fp)) == 0)) {

	    int rc;

	    syslog(LOG_NOTICE, "Removing stale lockfile for pid %d", pid);

	    rc = unlink(PIDFILE);

	    if (rc == -1) {

		perr("Cannot unlink " PIDFILE);

	    }

	} else {

	    pabort("Another atd already running with pid %d", pid);

	}

	fclose(fp);

	unlink(PIDFILE);

	fd = open(PIDFILE, O_RDWR | O_CREAT | O_EXCL,

		  S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);

	if (fd == -1)

	    perr("Cannot open " PIDFILE " the second time round");

    }

    if (lock_fd(fd) == -1)

	perr("Cannot lock " PIDFILE);

    fp = fdopen(fd, "w");

    if (fp == NULL)

	perr("Special weirdness: fdopen failed");

    fprintf(fp, "%d\n", getpid());

    /* We do NOT close fd, since we want to keep the lock. However, we don't

     * want to keep the file descriptor in case of an exec().

     */

    fflush(fp);

    fcntl(fd, F_SETFD, (long) 1);

    PRIV_END

    return;

}

void 

daemon_cleanup()

{

    PRIV_START

	unlink(PIDFILE);

    PRIV_END

}