1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 * Copyright (c) 2016 by Delphix. All rights reserved.
26 */
27
28 #include "lint.h"
29 #include "file64.h"
30 #include "mtlib.h"
31
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <unistd.h>
35 #include <fcntl.h>
36
37 #include "stdiom.h"
38
39 /*
40 * Use fork/setsid/fork to go into background and permanently remove
41 * controlling terminal.
42 */
43 int
daemon(int nochdir,int noclose)44 daemon(int nochdir, int noclose)
45 {
46 int retv, fd;
47
48 /*
49 * By the first fork+setsid, we disconnect from our current controlling
50 * terminal and become a session group leader.
51 */
52 retv = fork();
53 if (retv == -1)
54 return (-1);
55 if (retv != 0)
56 _exit(EXIT_SUCCESS);
57 if (setsid() == -1)
58 return (-1);
59 /*
60 * By forking again without calling setsid again, we make certain
61 * that we are not the session group leader and can never reacquire
62 * a controlling terminal.
63 */
64 retv = fork();
65 if (retv == -1)
66 return (-1);
67 if (retv != 0)
68 _exit(EXIT_SUCCESS);
69
70 if (nochdir == 0)
71 (void) chdir("/");
72
73 if (noclose == 0) {
74 /*
75 * Missing the PRIV_FILE_READ privilege may be one of the
76 * reasons that prevent the opening of /dev/null to succeed.
77 */
78 if ((fd = open("/dev/null", O_RDWR)) == -1)
79 return (-1);
80
81 /*
82 * Also, if any of the descriptor redirects fails we should
83 * return with error to signal to the caller that its request
84 * cannot be fulfilled properly. It is up to the caller to
85 * do the cleanup.
86 */
87 if ((fd != STDIN_FILENO) && (dup2(fd, STDIN_FILENO) < 0)) {
88 (void) close(fd);
89 return (-1);
90 }
91 if ((fd != STDOUT_FILENO) && (dup2(fd, STDOUT_FILENO) < 0)) {
92 (void) close(fd);
93 return (-1);
94 }
95 if ((fd != STDERR_FILENO) && (dup2(fd, STDERR_FILENO) < 0)) {
96 (void) close(fd);
97 return (-1);
98 }
99
100 if (fd > STDERR_FILENO)
101 (void) close(fd);
102 }
103 return (0);
104 }
105