1/*	$NetBSD: rumpuser_daemonize.c,v 1.10 2024/04/04 21:19:25 riastradh 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 1.10 2024/04/04 21:19:25 riastradh 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#if defined(HAVE_PATHS_H)
46#include <paths.h>
47#else
48#define _PATH_DEVNULL "/dev/null"
49#endif
50
51static int isdaemonizing;
52static int daemonpipe[2];
53
54#include <rump/rumpuser.h>
55
56static int
57openstdoutstderr(void)
58{
59	char path[PATH_MAX];
60	int fd;
61
62	if (getenv_r("RUMP_STDOUT", path, sizeof(path)) == 0) {
63		if ((fd = open(path, O_WRONLY|O_CREAT)) == -1)
64			return -1;
65		dup2(fd, STDOUT_FILENO);
66		(void)close(fd);
67	}
68	if (getenv_r("RUMP_STDERR", path, sizeof(path)) == 0) {
69		if ((fd = open(path, O_WRONLY|O_CREAT)) == -1)
70			return -1;
71		dup2(fd, STDERR_FILENO);
72		(void)close(fd);
73	}
74	return 0;
75}
76
77int
78rumpuser_daemonize_begin(void)
79{
80	ssize_t n;
81	int error;
82	int rv;
83
84	if (isdaemonizing) {
85		rv = EINPROGRESS;
86		goto out;
87	}
88	isdaemonizing = 1;
89
90	/*
91	 * For daemons we need to fork.  However, since we can't fork
92	 * after rump_init (which creates threads), do it now.  Add
93	 * a little pipe trickery to make sure we don't exit until the
94	 * service is fully inited (i.e. interlocked daemonization).
95	 * Actually, use socketpair since that allows to easily steer
96	 * clear of the dreaded sigpipe.
97	 *
98	 * Note: We do *NOT* host chdir("/").  It's up to the caller to
99	 * take care of that or not.
100	 */
101	if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) {
102		rv = errno;
103		goto out;
104	}
105
106	if (openstdoutstderr() == -1) {
107		rv = errno;
108		(void)close(daemonpipe[0]);
109		(void)close(daemonpipe[1]);
110		goto out;
111	}
112
113	switch (fork()) {
114	case 0:
115		if (setsid() == -1) {
116			rumpuser_daemonize_done(errno);
117		}
118		rv = 0;
119		break;
120	case -1:
121		rv = errno;
122		break;
123	default:
124		close(daemonpipe[1]);
125		n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL);
126		if (n == -1)
127			error = errno;
128		else if (n != sizeof(error))
129			error = ESRCH;
130		_exit(error);
131		/*NOTREACHED*/
132	}
133
134 out:
135	ET(rv);
136}
137
138int
139rumpuser_daemonize_done(int error)
140{
141	ssize_t n;
142	int fd, rv = 0;
143
144	if (!isdaemonizing) {
145		rv = ENOENT;
146		goto outout;
147	}
148
149	if (error == 0) {
150		fd = open(_PATH_DEVNULL, O_RDWR);
151		if (fd == -1) {
152			error = errno;
153			goto out;
154		}
155		dup2(fd, STDIN_FILENO);
156		if (getenv("RUMP_STDOUT") == NULL)
157			dup2(fd, STDOUT_FILENO);
158		if (getenv("RUMP_STDERR") == NULL)
159			dup2(fd, STDERR_FILENO);
160		if (fd > STDERR_FILENO)
161			close(fd);
162	}
163
164	fflush(stdout);
165	fflush(stderr);
166
167 out:
168	n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL);
169	if (n != sizeof(error)) {
170		rv = EPIPE;
171	} else if (n == -1) {
172		rv = errno;
173	} else {
174		close(daemonpipe[0]);
175		close(daemonpipe[1]);
176	}
177
178 outout:
179	ET(rv);
180}
181