1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/param.h>
33#include <sys/stat.h>
34
35#include <err.h>
36#include <errno.h>
37#include <fcntl.h>
38#include <signal.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42#include <unistd.h>
43
44static void dofile(void);
45static void usage(void) __dead2;
46
47#define	FILENAME	"nohup.out"
48/*
49 * POSIX mandates that we exit with:
50 * 126 - If the utility was found, but failed to execute.
51 * 127 - If any other error occurred.
52 */
53#define	EXIT_NOEXEC	126
54#define	EXIT_NOTFOUND	127
55#define	EXIT_MISC	127
56
57int
58main(int argc, char *argv[])
59{
60	int exit_status;
61
62	while (getopt(argc, argv, "") != -1)
63		usage();
64	argc -= optind;
65	argv += optind;
66	if (argc < 1)
67		usage();
68
69	if (isatty(STDOUT_FILENO))
70		dofile();
71	if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
72		/* may have just closed stderr */
73		err(EXIT_MISC, "%s", argv[0]);
74
75	(void)signal(SIGHUP, SIG_IGN);
76
77	execvp(*argv, argv);
78	exit_status = (errno == ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
79	err(exit_status, "%s", argv[0]);
80}
81
82static void
83dofile(void)
84{
85	int fd;
86	char path[MAXPATHLEN];
87	const char *p;
88
89	/*
90	 * POSIX mandates if the standard output is a terminal, the standard
91	 * output is appended to nohup.out in the working directory.  Failing
92	 * that, it will be appended to nohup.out in the directory obtained
93	 * from the HOME environment variable.  If file creation is required,
94	 * the mode_t is set to S_IRUSR | S_IWUSR.
95	 */
96	p = FILENAME;
97	fd = open(p, O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
98	if (fd != -1)
99		goto dupit;
100	if ((p = getenv("HOME")) != NULL && *p != '\0' &&
101	    (size_t)snprintf(path, sizeof(path), "%s/%s", p, FILENAME) <
102	    sizeof(path)) {
103		fd = open(p = path, O_RDWR | O_CREAT | O_APPEND,
104		    S_IRUSR | S_IWUSR);
105		if (fd != -1)
106			goto dupit;
107	}
108	errx(EXIT_MISC, "can't open a nohup.out file");
109
110dupit:
111	if (dup2(fd, STDOUT_FILENO) == -1)
112		err(EXIT_MISC, NULL);
113	(void)fprintf(stderr, "appending output to %s\n", p);
114}
115
116static void
117usage(void)
118{
119	(void)fprintf(stderr, "usage: nohup [--] utility [arguments]\n");
120	exit(EXIT_MISC);
121}
122