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system.c revision 1.25 
      1 /*	$NetBSD: system.c,v 1.25 2015/01/20 18:31:25 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988, 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/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)system.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: system.c,v 1.25 2015/01/20 18:31:25 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/types.h>
     43 #include <sys/wait.h>
     44 #include <errno.h>
     45 #include <signal.h>
     46 #include <stdlib.h>
     47 #include <unistd.h>
     48 #include <paths.h>
     49 
     50 #include "env.h"
     51 
     52 int
     53 system(const char *command)
     54 {
     55 	pid_t pid;
     56 	struct sigaction intsa, quitsa, sa;
     57 	sigset_t nmask, omask;
     58 	int pstat;
     59 	const char *argp[] = {"sh", "-c", NULL, NULL};
     60 	argp[2] = command;
     61 
     62 	/*
     63 	 * ISO/IEC 9899:1999 in 7.20.4.6 describes this special case.
     64 	 * We need to check availability of a command interpreter.
     65 	 */
     66 	if (command == NULL) {
     67 		if (access(_PATH_BSHELL, X_OK) == 0)
     68 			return 1;
     69 		return 0;
     70 	}
     71 
     72 	sa.sa_handler = SIG_IGN;
     73 	sigemptyset(&sa.sa_mask);
     74 	sa.sa_flags = 0;
     75 
     76 	if (sigaction(SIGINT, &sa, &intsa) == -1)
     77 		return -1;
     78 	if (sigaction(SIGQUIT, &sa, &quitsa) == -1) {
     79 		sigaction(SIGINT, &intsa, NULL);
     80 		return -1;
     81 	}
     82 
     83 	sigemptyset(&nmask);
     84 	sigaddset(&nmask, SIGCHLD);
     85 	if (sigprocmask(SIG_BLOCK, &nmask, &omask) == -1) {
     86 		sigaction(SIGINT, &intsa, NULL);
     87 		sigaction(SIGQUIT, &quitsa, NULL);
     88 		return -1;
     89 	}
     90 
     91 	(void)__readlockenv();
     92 	switch(pid = vfork()) {
     93 	case -1:			/* error */
     94 		(void)__unlockenv();
     95 		sigaction(SIGINT, &intsa, NULL);
     96 		sigaction(SIGQUIT, &quitsa, NULL);
     97 		(void)sigprocmask(SIG_SETMASK, &omask, NULL);
     98 		return -1;
     99 	case 0:				/* child */
    100 		sigaction(SIGINT, &intsa, NULL);
    101 		sigaction(SIGQUIT, &quitsa, NULL);
    102 		(void)sigprocmask(SIG_SETMASK, &omask, NULL);
    103 		execve(_PATH_BSHELL, __UNCONST(argp), environ);
    104 		_exit(127);
    105 	}
    106 	(void)__unlockenv();
    107 
    108 	while (waitpid(pid, &pstat, 0) == -1) {
    109 		if (errno != EINTR) {
    110 			pstat = -1;
    111 			break;
    112 		}
    113 	}
    114 
    115 	sigaction(SIGINT, &intsa, NULL);
    116 	sigaction(SIGQUIT, &quitsa, NULL);
    117 	(void)sigprocmask(SIG_SETMASK, &omask, NULL);
    118 
    119 	return (pstat);
    120 }
    121