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      1 /*	$NetBSD: nohup.c,v 1.15 2011/09/06 18:24:15 joerg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989 The Regents of the University of California.
      5  * 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/cdefs.h>
     33 #ifndef lint
     34 __COPYRIGHT("@(#) Copyright (c) 1989\
     35  The Regents of the University of California.  All rights reserved.");
     36 #endif /* not lint */
     37 
     38 #ifndef lint
     39 #if 0
     40 static char sccsid[] = "@(#)nohup.c	5.4 (Berkeley) 6/1/90";
     41 #endif
     42 __RCSID("$NetBSD: nohup.c,v 1.15 2011/09/06 18:24:15 joerg Exp $");
     43 #endif /* not lint */
     44 
     45 #include <sys/param.h>
     46 #include <sys/file.h>
     47 #include <sys/stat.h>
     48 #include <fcntl.h>
     49 #include <unistd.h>
     50 #include <signal.h>
     51 #include <stdio.h>
     52 #include <stdlib.h>
     53 #include <string.h>
     54 #include <errno.h>
     55 
     56 static void dofile(void);
     57 __dead static void usage(void);
     58 
     59 /* nohup shall exit with one of the following values:
     60    126 - The utility was found but could not be invoked.
     61    127 - An error occurred in the nohup utility, or the utility could
     62          not be found. */
     63 #define EXIT_NOEXEC	126
     64 #define EXIT_NOTFOUND	127
     65 #define EXIT_MISC	127
     66 
     67 int
     68 main(int argc, char **argv)
     69 {
     70 	int exit_status;
     71 
     72 	while (getopt(argc, argv, "") != -1) {
     73 		usage();
     74 	}
     75 	argc -= optind;
     76 	argv += optind;
     77 
     78 	if (argc < 1)
     79 		usage();
     80 
     81 	if (isatty(STDOUT_FILENO))
     82 		dofile();
     83 	if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
     84 		/* may have just closed stderr */
     85 		(void)fprintf(stdin, "nohup: %s\n", strerror(errno));
     86 		exit(EXIT_MISC);
     87 	}
     88 
     89 	/* The nohup utility shall take the standard action for all signals
     90 	   except that SIGHUP shall be ignored. */
     91 	(void)signal(SIGHUP, SIG_IGN);
     92 
     93 	execvp(argv[0], &argv[0]);
     94 	exit_status = (errno == ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
     95 	(void)fprintf(stderr, "nohup: %s: %s\n", argv[0], strerror(errno));
     96 	exit(exit_status);
     97 }
     98 
     99 static void
    100 dofile(void)
    101 {
    102 	int fd;
    103 	char path[MAXPATHLEN];
    104 	const char *p;
    105 
    106 	/* If the standard output is a terminal, all output written to
    107 	   its standard output shall be appended to the end of the file
    108 	   nohup.out in the current directory.  If nohup.out cannot be
    109 	   created or opened for appending, the output shall be appended
    110 	   to the end of the file nohup.out in the directory specified
    111 	   by the HOME environment variable.
    112 
    113 	   If a file is created, the file's permission bits shall be
    114 	   set to S_IRUSR | S_IWUSR. */
    115 #define	FILENAME	"nohup.out"
    116 	p = FILENAME;
    117 	if ((fd = open(p, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR)) >= 0)
    118 		goto dupit;
    119 	if ((p = getenv("HOME")) != NULL) {
    120 		(void)strlcpy(path, p, sizeof(path));
    121 		(void)strlcat(path, "/", sizeof(path));
    122 		(void)strlcat(path, FILENAME, sizeof(path));
    123 		if ((fd = open(p = path, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR)) >= 0)
    124 			goto dupit;
    125 	}
    126 	(void)fprintf(stderr, "nohup: can't open a nohup.out file.\n");
    127 	exit(EXIT_MISC);
    128 
    129 dupit:	(void)lseek(fd, 0L, SEEK_END);
    130 	if (dup2(fd, STDOUT_FILENO) == -1) {
    131 		(void)fprintf(stderr, "nohup: %s\n", strerror(errno));
    132 		exit(EXIT_MISC);
    133 	}
    134 	(void)fprintf(stderr, "sending output to %s\n", p);
    135 }
    136 
    137 static void
    138 usage(void)
    139 {
    140 	(void)fprintf(stderr, "usage: nohup utility [argument ...]\n");
    141 	exit(EXIT_MISC);
    142 }
    143