/*
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 2014 The FreeBSD Foundation
 * All rights reserved.
 *
 * This code is derived from software written by Ken Arnold and
 * published in UNIX Review, Vol. 6, No. 8.
 *
 * Portions of this software were developed by Edward Tomasz Napierala
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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 <sys/param.h>
#include <sys/queue.h>
#include <sys/wait.h>

#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <paths.h>

#include "common.h"

extern char **environ;

struct pid {
        SLIST_ENTRY(pid) next;
        FILE *outfp;
        pid_t pid;
        char *command;
};
static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);

#define ARGV_LEN        42

/*
 * Replacement for popen(3), without stdin (which we do not use), but with
 * stderr, proper logging, and improved command line arguments passing.
 * Error handling is built in - if it returns, then it succeeded.
 */
FILE *
auto_popen(const char *argv0, ...)
{
        va_list ap;
        struct pid *cur, *p;
        pid_t pid;
        int error, i, nullfd, outfds[2];
        char *arg, *argv[ARGV_LEN], *command;

        nullfd = open(_PATH_DEVNULL, O_RDWR, 0);
        if (nullfd < 0)
                log_err(1, "cannot open %s", _PATH_DEVNULL);

        error = pipe(outfds);
        if (error != 0)
                log_err(1, "pipe");

        cur = malloc(sizeof(struct pid));
        if (cur == NULL)
                log_err(1, "malloc");

        argv[0] = checked_strdup(argv0);
        command = argv[0];

        va_start(ap, argv0);
        for (i = 1;; i++) {
                if (i >= ARGV_LEN)
                        log_errx(1, "too many arguments to auto_popen");
                arg = va_arg(ap, char *);
                argv[i] = arg;
                if (arg == NULL)
                        break;

                command = concat(command, ' ', arg);
        }
        va_end(ap);

        cur->command = checked_strdup(command);

        switch (pid = fork()) {
        case -1:                        /* Error. */
                log_err(1, "fork");
                /* NOTREACHED */
        case 0:                         /* Child. */
                dup2(nullfd, STDIN_FILENO);
                dup2(outfds[1], STDOUT_FILENO);

                close(nullfd);
                close(outfds[0]);
                close(outfds[1]);

                SLIST_FOREACH(p, &pidlist, next)
                        close(fileno(p->outfp));
                execvp(argv[0], argv);
                log_err(1, "failed to execute %s", argv[0]);
                /* NOTREACHED */
        }

        log_debugx("executing \"%s\" as pid %d", command, pid);

        /* Parent; assume fdopen cannot fail. */
        cur->outfp = fdopen(outfds[0], "r");
        close(nullfd);
        close(outfds[1]);

        /* Link into list of file descriptors. */
        cur->pid = pid;
        SLIST_INSERT_HEAD(&pidlist, cur, next);

        return (cur->outfp);
}

int
auto_pclose(FILE *iop)
{
        struct pid *cur, *last = NULL;
        int status;
        pid_t pid;

        /*
         * Find the appropriate file pointer and remove it from the list.
         */
        SLIST_FOREACH(cur, &pidlist, next) {
                if (cur->outfp == iop)
                        break;
                last = cur;
        }
        if (cur == NULL) {
                return (-1);
        }
        if (last == NULL)
                SLIST_REMOVE_HEAD(&pidlist, next);
        else
                SLIST_REMOVE_AFTER(last, next);

        fclose(cur->outfp);

        do {
                pid = wait4(cur->pid, &status, 0, NULL);
        } while (pid == -1 && errno == EINTR);

        if (WIFSIGNALED(status)) {
                log_warnx("\"%s\", pid %d, terminated with signal %d",
                    cur->command, pid, WTERMSIG(status));
                return (status);
        }

        if (WEXITSTATUS(status) != 0) {
                log_warnx("\"%s\", pid %d, terminated with exit status %d",
                    cur->command, pid, WEXITSTATUS(status));
                return (status);
        }

        log_debugx("\"%s\", pid %d, terminated gracefully", cur->command, pid);

        free(cur->command);
        free(cur);

        return (pid == -1 ? -1 : status);
}