1 /* $NetBSD: system.c,v 1.28 2022/03/14 22:14:19 riastradh 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 1.28 2022/03/14 22:14:19 riastradh 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 <spawn.h> 50 51 #include "env.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, sigdefault; 59 int pstat; 60 const char *argp[] = {"sh", "-c", "--", command, NULL}; 61 posix_spawnattr_t attr; 62 int error; 63 64 /* 65 * ISO/IEC 9899:1999 in 7.20.4.6 describes this special case. 66 * We need to check availability of a command interpreter. 67 */ 68 if (command == NULL) { 69 if (access(_PATH_BSHELL, X_OK) == 0) 70 return 1; 71 return 0; 72 } 73 74 sa.sa_handler = SIG_IGN; 75 sigemptyset(&sa.sa_mask); 76 sa.sa_flags = 0; 77 78 if (sigaction(SIGINT, &sa, &intsa) == -1) 79 return -1; 80 if (sigaction(SIGQUIT, &sa, &quitsa) == -1) { 81 sigaction(SIGINT, &intsa, NULL); 82 return -1; 83 } 84 85 sigemptyset(&nmask); 86 sigaddset(&nmask, SIGCHLD); 87 if (sigprocmask(SIG_BLOCK, &nmask, &omask) == -1) { 88 sigaction(SIGINT, &intsa, NULL); 89 sigaction(SIGQUIT, &quitsa, NULL); 90 return -1; 91 } 92 93 /* 94 * We arrange to inherit all signal handlers from the caller by 95 * default, except possibly SIGINT and SIGQUIT. These we have 96 * overridden internally for system(3) to be SIG_IGN. 97 * 98 * - If the caller had SIGINT or SIGQUIT at SIG_IGN, then we 99 * inherit them as is -- caller had SIG_IGN, child will too. 100 * 101 * - Otherwise, they are SIG_DFL or a signal handler, and we 102 * must reset them to SIG_DFL in the child, rather than 103 * SIG_IGN in system(3) in the parent, by including them in 104 * the sigdefault set. 105 */ 106 sigemptyset(&sigdefault); 107 if (intsa.sa_handler != SIG_IGN) 108 sigaddset(&sigdefault, SIGINT); 109 if (quitsa.sa_handler != SIG_IGN) 110 sigaddset(&sigdefault, SIGQUIT); 111 112 posix_spawnattr_init(&attr); 113 posix_spawnattr_setsigdefault(&attr, &sigdefault); 114 posix_spawnattr_setsigmask(&attr, &omask); 115 posix_spawnattr_setflags(&attr, 116 POSIX_SPAWN_SETSIGDEF|POSIX_SPAWN_SETSIGMASK); 117 (void)__readlockenv(); 118 error = posix_spawn(&pid, _PATH_BSHELL, NULL, &attr, __UNCONST(argp), 119 environ); 120 (void)__unlockenv(); 121 posix_spawnattr_destroy(&attr); 122 123 if (error) { 124 errno = error; 125 pstat = -1; 126 goto out; 127 } 128 129 while (waitpid(pid, &pstat, 0) == -1) { 130 if (errno != EINTR) { 131 pstat = -1; 132 break; 133 } 134 } 135 136 out: sigaction(SIGINT, &intsa, NULL); 137 sigaction(SIGQUIT, &quitsa, NULL); 138 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 139 140 return (pstat); 141 } 142