/*      $NetBSD: rumpuser_daemonize.c,v 1.10 2024/04/04 21:19:25 riastradh Exp $        */

/*
 * Copyright (c) 2010 Antti Kantee.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR OR CONTRIBUTORS 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.
 */

#include "rumpuser_port.h"

#if !defined(lint)
__RCSID("$NetBSD: rumpuser_daemonize.c,v 1.10 2024/04/04 21:19:25 riastradh Exp $");
#endif /* !lint */

#include <sys/types.h>
#include <sys/socket.h>

#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <unistd.h>

#include "rumpuser_int.h"

#if defined(HAVE_PATHS_H)
#include <paths.h>
#else
#define _PATH_DEVNULL "/dev/null"
#endif

static int isdaemonizing;
static int daemonpipe[2];

#include <rump/rumpuser.h>

static int
openstdoutstderr(void)
{
        char path[PATH_MAX];
        int fd;

        if (getenv_r("RUMP_STDOUT", path, sizeof(path)) == 0) {
                if ((fd = open(path, O_WRONLY|O_CREAT)) == -1)
                        return -1;
                dup2(fd, STDOUT_FILENO);
                (void)close(fd);
        }
        if (getenv_r("RUMP_STDERR", path, sizeof(path)) == 0) {
                if ((fd = open(path, O_WRONLY|O_CREAT)) == -1)
                        return -1;
                dup2(fd, STDERR_FILENO);
                (void)close(fd);
        }
        return 0;
}

int
rumpuser_daemonize_begin(void)
{
        ssize_t n;
        int error;
        int rv;

        if (isdaemonizing) {
                rv = EINPROGRESS;
                goto out;
        }
        isdaemonizing = 1;

        /*
         * For daemons we need to fork.  However, since we can't fork
         * after rump_init (which creates threads), do it now.  Add
         * a little pipe trickery to make sure we don't exit until the
         * service is fully inited (i.e. interlocked daemonization).
         * Actually, use socketpair since that allows to easily steer
         * clear of the dreaded sigpipe.
         *
         * Note: We do *NOT* host chdir("/").  It's up to the caller to
         * take care of that or not.
         */
        if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) {
                rv = errno;
                goto out;
        }

        if (openstdoutstderr() == -1) {
                rv = errno;
                (void)close(daemonpipe[0]);
                (void)close(daemonpipe[1]);
                goto out;
        }

        switch (fork()) {
        case 0:
                if (setsid() == -1) {
                        rumpuser_daemonize_done(errno);
                }
                rv = 0;
                break;
        case -1:
                rv = errno;
                break;
        default:
                close(daemonpipe[1]);
                n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL);
                if (n == -1)
                        error = errno;
                else if (n != sizeof(error))
                        error = ESRCH;
                _exit(error);
                /*NOTREACHED*/
        }

 out:
        ET(rv);
}

int
rumpuser_daemonize_done(int error)
{
        ssize_t n;
        int fd, rv = 0;

        if (!isdaemonizing) {
                rv = ENOENT;
                goto outout;
        }

        if (error == 0) {
                fd = open(_PATH_DEVNULL, O_RDWR);
                if (fd == -1) {
                        error = errno;
                        goto out;
                }
                dup2(fd, STDIN_FILENO);
                if (getenv("RUMP_STDOUT") == NULL)
                        dup2(fd, STDOUT_FILENO);
                if (getenv("RUMP_STDERR") == NULL)
                        dup2(fd, STDERR_FILENO);
                if (fd > STDERR_FILENO)
                        close(fd);
        }

        fflush(stdout);
        fflush(stderr);

 out:
        n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL);
        if (n != sizeof(error)) {
                rv = EPIPE;
        } else if (n == -1) {
                rv = errno;
        } else {
                close(daemonpipe[0]);
                close(daemonpipe[1]);
        }

 outout:
        ET(rv);
}