1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 "namespace.h"
33 #include <sys/types.h>
34 #include <sys/wait.h>
35
36 #include <errno.h>
37 #include <paths.h>
38 #include <signal.h>
39 #include <stddef.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43 #include "un-namespace.h"
44 #include "libc_private.h"
45 #include "spinlock.h"
46
47 #pragma weak system
48 int
system(const char * command)49 system(const char *command)
50 {
51 return (((int (*)(const char *))
52 __libc_interposing[INTERPOS_system])(command));
53 }
54
55 int
__libc_system(const char * command)56 __libc_system(const char *command)
57 {
58 static spinlock_t lock = _SPINLOCK_INITIALIZER;
59 static volatile unsigned long concurrent;
60 static struct sigaction ointact, oquitact;
61 struct sigaction ign;
62 sigset_t sigblock, osigblock;
63 char *argv[] = { "sh", "-c", __DECONST(char *, command), NULL };
64 extern char **environ;
65 int pstat = -1, serrno = 0;
66 pid_t pid;
67
68 if (command == NULL) /* just checking... */
69 return (eaccess(_PATH_BSHELL, X_OK) == 0);
70
71 /*
72 * If we are the first concurrent instance, ignore SIGINT and
73 * SIGQUIT. Block SIGCHLD regardless of concurrency, since on
74 * FreeBSD, sigprocmask() is equivalent to pthread_sigmask().
75 */
76 if (__isthreaded)
77 _SPINLOCK(&lock);
78 if (concurrent++ == 0) {
79 memset(&ign, 0, sizeof(ign));
80 ign.sa_handler = SIG_IGN;
81 sigemptyset(&ign.sa_mask);
82 (void)__libc_sigaction(SIGINT, &ign, &ointact);
83 (void)__libc_sigaction(SIGQUIT, &ign, &oquitact);
84 }
85 sigemptyset(&sigblock);
86 sigaddset(&sigblock, SIGCHLD);
87 (void)__libc_sigprocmask(SIG_BLOCK, &sigblock, &osigblock);
88 if (__isthreaded)
89 _SPINUNLOCK(&lock);
90
91 /*
92 * Fork the child process.
93 */
94 if ((pid = fork()) < 0) { /* error */
95 serrno = errno;
96 } else if (pid == 0) { /* child */
97 /*
98 * Restore original signal dispositions.
99 */
100 (void)__libc_sigaction(SIGINT, &ointact, NULL);
101 (void)__libc_sigaction(SIGQUIT, &oquitact, NULL);
102 (void)__sys_sigprocmask(SIG_SETMASK, &osigblock, NULL);
103 /*
104 * Exec the command.
105 */
106 _execve(_PATH_BSHELL, argv, environ);
107 _exit(127);
108 } else { /* parent */
109 /*
110 * Wait for the child to terminate.
111 */
112 while (_wait4(pid, &pstat, 0, NULL) < 0) {
113 if (errno != EINTR) {
114 serrno = errno;
115 break;
116 }
117 }
118 }
119
120 /*
121 * If we are the last concurrent instance, restore original signal
122 * dispositions. Unblock SIGCHLD, unless it was already blocked.
123 */
124 if (__isthreaded)
125 _SPINLOCK(&lock);
126 if (--concurrent == 0) {
127 (void)__libc_sigaction(SIGINT, &ointact, NULL);
128 (void)__libc_sigaction(SIGQUIT, &oquitact, NULL);
129 }
130 if (!sigismember(&osigblock, SIGCHLD))
131 (void)__libc_sigprocmask(SIG_UNBLOCK, &sigblock, NULL);
132 if (__isthreaded)
133 _SPINUNLOCK(&lock);
134 if (serrno != 0)
135 errno = serrno;
136 return (pstat);
137 }
138
139 __weak_reference(__libc_system, __system);
140 __weak_reference(__libc_system, _system);
141