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rumpuser_daemonize.c revision 1.2.4.3 
      1 /*	$NetBSD: rumpuser_daemonize.c,v 1.2.4.3 2014/05/22 11:37:00 yamt 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 1.2.4.3 2014/05/22 11:37:00 yamt 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 <stdint.h>
     40 #include <stdio.h>
     41 #include <unistd.h>
     42 
     43 #include "rumpuser_int.h"
     44 
     45 #ifdef __sun__
     46 #define _PATH_DEVNULL "/dev/null"
     47 #else
     48 #include <paths.h>
     49 #endif
     50 
     51 static int isdaemonizing;
     52 static int daemonpipe[2];
     53 
     54 #include <rump/rumpuser.h>
     55 
     56 int
     57 rumpuser_daemonize_begin(void)
     58 {
     59 	ssize_t n;
     60 	int error;
     61 	int rv;
     62 
     63 	if (isdaemonizing) {
     64 		rv = EINPROGRESS;
     65 		goto out;
     66 	}
     67 	isdaemonizing = 1;
     68 
     69 	/*
     70 	 * For daemons we need to fork.  However, since we can't fork
     71 	 * after rump_init (which creates threads), do it now.  Add
     72 	 * a little pipe trickery to make sure we don't exit until the
     73 	 * service is fully inited (i.e. interlocked daemonization).
     74 	 * Actually, use sucketpair since that allows to easily steer
     75 	 * clear of the dreaded sigpipe.
     76 	 *
     77 	 * Note: We do *NOT* host chdir("/").  It's up to the caller to
     78 	 * take care of that or not.
     79 	 */
     80 	if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) {
     81 		rv = errno;
     82 		goto out;
     83 	}
     84 
     85 	switch (fork()) {
     86 	case 0:
     87 		if (setsid() == -1) {
     88 			rumpuser_daemonize_done(errno);
     89 		}
     90 		rv = 0;
     91 		break;
     92 	case -1:
     93 		rv = errno;
     94 		break;
     95 	default:
     96 		close(daemonpipe[1]);
     97 		n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL);
     98 		if (n == -1)
     99 			error = errno;
    100 		else if (n != sizeof(error))
    101 			error = ESRCH;
    102 		_exit(error);
    103 		/*NOTREACHED*/
    104 	}
    105 
    106  out:
    107 	ET(rv);
    108 }
    109 
    110 int
    111 rumpuser_daemonize_done(int error)
    112 {
    113 	ssize_t n;
    114 	int fd, rv = 0;
    115 
    116 	if (!isdaemonizing) {
    117 		rv = ENOENT;
    118 		goto outout;
    119 	}
    120 
    121 	if (error == 0) {
    122 		fd = open(_PATH_DEVNULL, O_RDWR);
    123 		if (fd == -1) {
    124 			error = errno;
    125 			goto out;
    126 		}
    127 		dup2(fd, STDIN_FILENO);
    128 		dup2(fd, STDOUT_FILENO);
    129 		dup2(fd, STDERR_FILENO);
    130 		if (fd > STDERR_FILENO)
    131 			close(fd);
    132 	}
    133 
    134  out:
    135 	n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL);
    136 	if (n != sizeof(error)) {
    137 		rv = EPIPE;
    138 	} else if (n == -1) {
    139 		rv = errno;
    140 	} else {
    141 		close(daemonpipe[0]);
    142 		close(daemonpipe[1]);
    143 	}
    144 
    145  outout:
    146 	ET(rv);
    147 }
    148