system.c revision 16117 
1/*
2 * Copyright (c) 1988, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)system.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/types.h>
39#include <sys/wait.h>
40#include <signal.h>
41#include <stdlib.h>
42#include <stddef.h>
43#include <unistd.h>
44#include <paths.h>
45#include <errno.h>
46
47int system(command)
48	const char *command;
49{
50	pid_t pid;
51	int pstat;
52	struct sigaction ign, intact, quitact;
53	sigset_t newsigblock, oldsigblock;
54
55	if (!command)		/* just checking... */
56		return(1);
57
58	/*
59	 * Ignore SIGINT and SIGQUIT, block SIGCHLD. Remember to save
60	 * existing signal dispositions.
61	 */
62	ign.sa_handler = SIG_IGN;
63	(void)sigemptyset(&ign.sa_mask);
64	ign.sa_flags = 0;
65	(void)sigaction(SIGINT, &ign, &intact);
66	(void)sigaction(SIGQUIT, &ign, &quitact);
67	(void)sigemptyset(&newsigblock);
68	sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
69	switch(pid = fork()) {
70	case -1:			/* error */
71		break;
72	case 0:				/* child */
73		/*
74		 * Restore original signal dispositions and exec the command.
75		 */
76		(void)sigaction(SIGINT, &intact, NULL);
77		(void)sigaction(SIGQUIT,  &quitact, NULL);
78		(void)sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
79		execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
80		_exit(127);
81	default:			/* parent */
82		do {
83			pid = waitpid(pid, &pstat, 0);
84		} while (pid == -1 && errno == EINTR);
85		break;
86	}
87	(void)sigaction(SIGINT, &intact, NULL);
88	(void)sigaction(SIGQUIT,  &quitact, NULL);
89	(void)sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
90	return(pid == -1 ? -1 : pstat);
91}
92