lib/libc/stdlib/system.c

   1 /*      $NetBSD: system.c,v 1.24 2012/06/25 22:32:45 abs 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 1.24 2012/06/25 22:32:45 abs 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 #include "reentrant.h"
  52
  53 int
  54 system(const char *command)
  55 {
  56         pid_t pid;
  57         struct sigaction intsa, quitsa, sa;
  58         sigset_t nmask, omask;
  59         int pstat;
  60         const char *argp[] = {"sh", "-c", NULL, NULL};
  61         argp[2] = command;
  62
  63         /*
  64          * ISO/IEC 9899:1999 in 7.20.4.6 describes this special case.
  65          * We need to check availability of a command interpreter.
  66          */
  67         if (command == NULL) {
  68                 if (access(_PATH_BSHELL, X_OK) == 0)
  69                         return 1;
  70                 return 0;
  71         }
  72
  73         sa.sa_handler = SIG_IGN;
  74         sigemptyset(&sa.sa_mask);
  75         sa.sa_flags = 0;
  76
  77         if (sigaction(SIGINT, &sa, &intsa) == -1)
  78                 return -1;
  79         if (sigaction(SIGQUIT, &sa, &quitsa) == -1) {
  80                 sigaction(SIGINT, &intsa, NULL);
  81                 return -1;
  82         }
  83
  84         sigemptyset(&nmask);
  85         sigaddset(&nmask, SIGCHLD);
  86         if (sigprocmask(SIG_BLOCK, &nmask, &omask) == -1) {
  87                 sigaction(SIGINT, &intsa, NULL);
  88                 sigaction(SIGQUIT, &quitsa, NULL);
  89                 return -1;
  90         }
  91
  92         (void)__readlockenv();
  93         switch(pid = vfork()) {
  94         case -1:                        /* error */
  95                 (void)__unlockenv();
  96                 sigaction(SIGINT, &intsa, NULL);
  97                 sigaction(SIGQUIT, &quitsa, NULL);
  98                 (void)sigprocmask(SIG_SETMASK, &omask, NULL);
  99                 return -1;
 100         case 0:                         /* child */
 101                 sigaction(SIGINT, &intsa, NULL);
 102                 sigaction(SIGQUIT, &quitsa, NULL);
 103                 (void)sigprocmask(SIG_SETMASK, &omask, NULL);
 104                 execve(_PATH_BSHELL, __UNCONST(argp), environ);
 105                 _exit(127);
 106         }
 107         (void)__unlockenv();
 108
 109         while (waitpid(pid, &pstat, 0) == -1) {
 110                 if (errno != EINTR) {
 111                         pstat = -1;
 112                         break;
 113                 }
 114         }
 115
 116         sigaction(SIGINT, &intsa, NULL);
 117         sigaction(SIGQUIT, &quitsa, NULL);
 118         (void)sigprocmask(SIG_SETMASK, &omask, NULL);
 119
 120         return (pstat);
 121 }