NetBSD/lib/librumpuser/rumpuser_daemonize.c

125 lines
3.3 KiB
C

/* $NetBSD: rumpuser_daemonize.c,v 1.2 2011/01/22 14:18:55 pooka 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 <sys/cdefs.h>
#if !defined(lint)
__RCSID("$NetBSD: rumpuser_daemonize.c,v 1.2 2011/01/22 14:18:55 pooka Exp $");
#endif /* !lint */
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <unistd.h>
static int isdaemonizing;
static int daemonpipe[2];
#include <rump/rumpuser.h>
int
rumpuser_daemonize_begin(void)
{
ssize_t n;
int error;
if (isdaemonizing)
return EINPROGRESS;
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 sucketpair 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) {
return errno;
}
switch (fork()) {
case 0:
if (setsid() == -1) {
rumpuser_daemonize_done(errno);
}
return 0;
case -1:
return errno;
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*/
}
}
int
rumpuser_daemonize_done(int error)
{
ssize_t n;
int fd;
if (!isdaemonizing)
return ENOENT;
if (error == 0) {
fd = open(_PATH_DEVNULL, O_RDWR);
if (fd == -1) {
error = errno;
goto out;
}
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
close(fd);
}
out:
n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL);
if (n != sizeof(error))
return EPIPE;
else if (n == -1)
return errno;
close(daemonpipe[0]);
close(daemonpipe[1]);
return 0;
}