lib/libc/stdlib/system.c

   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 }