/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "namespace.h"
#include <sys/types.h>
#include <sys/wait.h>

#include <errno.h>
#include <paths.h>
#include <signal.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "spinlock.h"

#pragma weak system
int
system(const char *command)
{
        return (((int (*)(const char *))
            __libc_interposing[INTERPOS_system])(command));
}

int
__libc_system(const char *command)
{
        static spinlock_t lock = _SPINLOCK_INITIALIZER;
        static volatile unsigned long concurrent;
        static struct sigaction ointact, oquitact;
        struct sigaction ign;
        sigset_t sigblock, osigblock;
        char *argv[] = { "sh", "-c", __DECONST(char *, command), NULL };
        extern char **environ;
        int pstat = -1, serrno = 0;
        pid_t pid;

        if (command == NULL)                    /* just checking... */
                return (eaccess(_PATH_BSHELL, X_OK) == 0);

        /*
         * If we are the first concurrent instance, ignore SIGINT and
         * SIGQUIT.  Block SIGCHLD regardless of concurrency, since on
         * FreeBSD, sigprocmask() is equivalent to pthread_sigmask().
         */
        if (__isthreaded)
                _SPINLOCK(&lock);
        if (concurrent++ == 0) {
                memset(&ign, 0, sizeof(ign));
                ign.sa_handler = SIG_IGN;
                sigemptyset(&ign.sa_mask);
                (void)__libc_sigaction(SIGINT, &ign, &ointact);
                (void)__libc_sigaction(SIGQUIT, &ign, &oquitact);
        }
        sigemptyset(&sigblock);
        sigaddset(&sigblock, SIGCHLD);
        (void)__libc_sigprocmask(SIG_BLOCK, &sigblock, &osigblock);
        if (__isthreaded)
                _SPINUNLOCK(&lock);

        /*
         * Fork the child process.
         */
        if ((pid = fork()) < 0) {               /* error */
                serrno = errno;
        } else if (pid == 0) {                  /* child */
                /*
                 * Restore original signal dispositions.
                 */
                (void)__libc_sigaction(SIGINT, &ointact, NULL);
                (void)__libc_sigaction(SIGQUIT,  &oquitact, NULL);
                (void)__sys_sigprocmask(SIG_SETMASK, &osigblock, NULL);
                /*
                 * Exec the command.
                 */
                _execve(_PATH_BSHELL, argv, environ);
                _exit(127);
        } else {                                /* parent */
                /*
                 * Wait for the child to terminate.
                 */
                while (_wait4(pid, &pstat, 0, NULL) < 0) {
                        if (errno != EINTR) {
                                serrno = errno;
                                break;
                        }
                }
        }

        /*
         * If we are the last concurrent instance, restore original signal
         * dispositions.  Unblock SIGCHLD, unless it was already blocked.
         */
        if (__isthreaded)
                _SPINLOCK(&lock);
        if (--concurrent == 0) {
                (void)__libc_sigaction(SIGINT, &ointact, NULL);
                (void)__libc_sigaction(SIGQUIT,  &oquitact, NULL);
        }
        if (!sigismember(&osigblock, SIGCHLD))
                (void)__libc_sigprocmask(SIG_UNBLOCK, &sigblock, NULL);
        if (__isthreaded)
                _SPINUNLOCK(&lock);
        if (serrno != 0)
                errno = serrno;
        return (pstat);
}

__weak_reference(__libc_system, __system);
__weak_reference(__libc_system, _system);