/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include "mt.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <wait.h>
#include <fcntl.h>
#include <thread.h>
#include <unistd.h>
#include <errno.h>
#include <ucontext.h>
#include <syslog.h>
#include <rpcsvc/daemon_utils.h>

static int open_daemon_lock(const char *, int);

/*
 * Use an advisory lock to ensure that only one daemon process is
 * active in the system at any point in time. If the lock is held
 * by another process, do not block but return the pid owner of
 * the lock to the caller immediately. The lock is cleared if the
 * holding daemon process exits for any reason even if the lock
 * file remains, so the daemon can be restarted if necessary.
 */

/*
 * check if another process is holding lock on the lock file.
 *
 * return: 0 if file is not locked, else,
 *         1 if file is locked by another process, else,
 *         -1 on any error.
 */
int
_check_daemon_lock(const char *name)
{
        int             fd, err;
        struct flock    lock;

        if ((fd = open_daemon_lock(name, O_RDONLY)) == -1) {
                if (errno == ENOENT)
                        return (0);
                return (-1);
        }

        lock.l_type = F_WRLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = (off_t)0;
        lock.l_len = (off_t)0;

        err = fcntl(fd, F_GETLK, &lock);
        (void) close(fd);

        if (err == -1)
                return (-1);

        return ((lock.l_type == F_UNLCK) ? 0 : 1);
}

static int
open_daemon_lock(const char *name, int mode)
{
        char            lock_file[MAXPATHLEN], buf[MAXPATHLEN];
        int             fd;
        char            *p;

        /*
         * Our args look like this:
         *   svc:/network/nfs/status:default
         * We want to create a lock file named like this:
         *   /etc/svc/volatile/nfs-status.lock
         * i.e., we want the last two path components in the name.
         */
        (void) strncpy(buf, name, MAXPATHLEN);

        /* First, strip off ":<instance>", if present. */
        p = strrchr(buf, ':');
        if (p != NULL)
                *p = '\0';

        /* Next, find final '/' and replace it with a dash */
        p = strrchr(buf, '/');
        if (p == NULL)
                p = buf;
        else {
                *p = '-';
                /* Now find the start of what we want our name to be */
                p = strrchr(buf, '/');
                if (p == NULL)
                        p = buf;
                else
                        p++;
        }

        (void) snprintf(lock_file, MAXPATHLEN, "/etc/svc/volatile/%s.lock", p);

        if ((fd = open(lock_file, mode, 0644)) == -1)
                return (-1);

        if (mode & O_CREAT)
                (void) fchmod(fd, 0644);

        return (fd);
}
/*
 * lock the file, write caller's pid to the lock file
 * return: 0 if caller can establish lock, else,
 *         pid of the current lock holder, else,
 *         -1 on any printable error.
 */
pid_t
_enter_daemon_lock(const char *name)
{
        int             fd;
        pid_t           pid;
        char            line[BUFSIZ];
        struct flock    lock;

        pid = getpid();
        (void) snprintf(line, sizeof (line), "%ld\n", pid);

        if ((fd = open_daemon_lock(name, O_RDWR|O_CREAT)) == -1)
                return ((pid_t)-1);

        lock.l_type = F_WRLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = (off_t)0;
        lock.l_len = (off_t)0;

        if (fcntl(fd, F_SETLK, &lock) == -1) {
                if (fcntl(fd, F_GETLK, &lock) == -1) {
                        (void) close(fd);
                        return ((pid_t)-1);
                }
                (void) close(fd);
                return (lock.l_pid);
        }

        if (write(fd, line, strlen(line)) == -1) {
                (void) close(fd);
                return ((pid_t)-1);
        }

        return ((pid_t)0);
}

int
_create_daemon_lock(const char *name, uid_t uid, gid_t gid)
{
        int fd = open_daemon_lock(name, O_CREAT);
        int ret;

        if (fd < 0)
                return (-1);

        ret = fchown(fd, uid, gid);
        (void) close(fd);

        return (ret);
}