lib/libc/stdlib/system.c

   1 /*      $NetBSD: system.c,v 1.21 2006/10/07 22:16:19 elad 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 1.21 2006/10/07 22:16:19 elad 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 #include "reentrant.h"
  50
  51 #ifdef _REENTRANT
  52 extern rwlock_t __environ_lock;
  53 #endif
  54 extern char **environ;
  55
  56 int
  57 system(command)
  58         const char *command;
  59 {
  60         pid_t pid;
  61         struct sigaction intsa, quitsa, sa;
  62         sigset_t nmask, omask;
  63         int pstat;
  64         const char *argp[] = {"sh", "-c", NULL, NULL};
  65         argp[2] = command;
  66
  67         /*
  68          * ISO/IEC 9899:1999 in 7.20.4.6 describes this special case.
  69          * We need to check availability of a command interpreter.
  70          */
  71         if (command == NULL) {
  72                 if (access(_PATH_BSHELL, X_OK) == 0)
  73                         return 1;
  74                 return 0;
  75         }
  76
  77         sa.sa_handler = SIG_IGN;
  78         sigemptyset(&sa.sa_mask);
  79         sa.sa_flags = 0;
  80
  81         if (sigaction(SIGINT, &sa, &intsa) == -1)
  82                 return -1;
  83         if (sigaction(SIGQUIT, &sa, &quitsa) == -1) {
  84                 sigaction(SIGINT, &intsa, NULL);
  85                 return -1;
  86         }
  87
  88         sigemptyset(&nmask);
  89         sigaddset(&nmask, SIGCHLD);
  90         if (sigprocmask(SIG_BLOCK, &nmask, &omask) == -1) {
  91                 sigaction(SIGINT, &intsa, NULL);
  92                 sigaction(SIGQUIT, &quitsa, NULL);
  93                 return -1;
  94         }
  95
  96         rwlock_rdlock(&__environ_lock);
  97         switch(pid = vfork()) {
  98         case -1:                        /* error */
  99                 rwlock_unlock(&__environ_lock);
 100                 sigaction(SIGINT, &intsa, NULL);
 101                 sigaction(SIGQUIT, &quitsa, NULL);
 102                 (void)sigprocmask(SIG_SETMASK, &omask, NULL);
 103                 return -1;
 104         case 0:                         /* child */
 105                 sigaction(SIGINT, &intsa, NULL);
 106                 sigaction(SIGQUIT, &quitsa, NULL);
 107                 (void)sigprocmask(SIG_SETMASK, &omask, NULL);
 108                 execve(_PATH_BSHELL, __UNCONST(argp), environ);
 109                 _exit(127);
 110         }
 111         rwlock_unlock(&__environ_lock);
 112
 113         while (waitpid(pid, &pstat, 0) == -1) {
 114                 if (errno != EINTR) {
 115                         pstat = -1;
 116                         break;
 117                 }
 118         }
 119
 120         sigaction(SIGINT, &intsa, NULL);
 121         sigaction(SIGQUIT, &quitsa, NULL);
 122         (void)sigprocmask(SIG_SETMASK, &omask, NULL);
 123
 124         return (pstat);
 125 }