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rumpuser_daemonize.c revision 1.4 
      1 /*	$NetBSD: rumpuser_daemonize.c,v 1.4 2012/11/18 19:29:40 pooka Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2010 Antti Kantee.  All Rights Reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     16  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include "rumpuser_port.h"
     29 
     30 #if !defined(lint)
     31 __RCSID("$NetBSD: rumpuser_daemonize.c,v 1.4 2012/11/18 19:29:40 pooka Exp $");
     32 #endif /* !lint */
     33 
     34 #include <sys/types.h>
     35 #include <sys/socket.h>
     36 
     37 #include <errno.h>
     38 #include <fcntl.h>
     39 #include <stdio.h>
     40 #include <unistd.h>
     41 
     42 #ifdef __sun__
     43 #define _PATH_DEVNULL "/dev/null"
     44 #else
     45 #include <paths.h>
     46 #endif
     47 
     48 static int isdaemonizing;
     49 static int daemonpipe[2];
     50 
     51 #include <rump/rumpuser.h>
     52 
     53 int
     54 rumpuser_daemonize_begin(void)
     55 {
     56 	ssize_t n;
     57 	int error;
     58 
     59 	if (isdaemonizing)
     60 		return EINPROGRESS;
     61 	isdaemonizing = 1;
     62 
     63 	/*
     64 	 * For daemons we need to fork.  However, since we can't fork
     65 	 * after rump_init (which creates threads), do it now.  Add
     66 	 * a little pipe trickery to make sure we don't exit until the
     67 	 * service is fully inited (i.e. interlocked daemonization).
     68 	 * Actually, use sucketpair since that allows to easily steer
     69 	 * clear of the dreaded sigpipe.
     70 	 *
     71 	 * Note: We do *NOT* host chdir("/").  It's up to the caller to
     72 	 * take care of that or not.
     73 	 */
     74 	if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) {
     75 		return errno;
     76 	}
     77 
     78 	switch (fork()) {
     79 	case 0:
     80 		if (setsid() == -1) {
     81 			rumpuser_daemonize_done(errno);
     82 		}
     83 		return 0;
     84 	case -1:
     85 		return errno;
     86 	default:
     87 		close(daemonpipe[1]);
     88 		n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL);
     89 		if (n == -1)
     90 			error = errno;
     91 		else if (n != sizeof(error))
     92 			error = ESRCH;
     93 		_exit(error);
     94 		/*NOTREACHED*/
     95 	}
     96 }
     97 
     98 int
     99 rumpuser_daemonize_done(int error)
    100 {
    101 	ssize_t n;
    102 	int fd;
    103 
    104 	if (!isdaemonizing)
    105 		return ENOENT;
    106 
    107 	if (error == 0) {
    108 		fd = open(_PATH_DEVNULL, O_RDWR);
    109 		if (fd == -1) {
    110 			error = errno;
    111 			goto out;
    112 		}
    113 		dup2(fd, STDIN_FILENO);
    114 		dup2(fd, STDOUT_FILENO);
    115 		dup2(fd, STDERR_FILENO);
    116 		if (fd > STDERR_FILENO)
    117 			close(fd);
    118 	}
    119 
    120  out:
    121 	n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL);
    122 	if (n != sizeof(error))
    123 		return EPIPE;
    124 	else if (n == -1)
    125 		return errno;
    126 	close(daemonpipe[0]);
    127 	close(daemonpipe[1]);
    128 
    129 	return 0;
    130 }
    131