/*      $OpenBSD: kqueue-exec.c,v 1.1 2023/08/20 15:19:34 visa Exp $    */

/*
 * Copyright (c) 2023 Visa Hankala
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "main.h"

static void     do_exec_child(void);
static void     do_exec_parent(const char *, int);

int
do_exec(const char *argv0)
{
        do_exec_parent(argv0, 0);
        do_exec_parent(argv0, 1);
        return 0;
}

static void
do_exec_parent(const char *argv0, int cloexec)
{
        char *args[] = {
                (char *)argv0,
                "-e",
                NULL
        };
        char fdbuf[12];
        pid_t pid;
        int kq, status;

        if (getenv("REGRESS_KQUEUE_FD") != NULL) {
                do_exec_child();
                _exit(0);
        }

        pid = fork();
        if (pid == -1)
                err(1, "fork");
        if (pid == 0) {
                kq = kqueue1(cloexec ? O_CLOEXEC : 0);
                if (kq == -1)
                        err(1, "kqueue1");
                snprintf(fdbuf, sizeof(fdbuf), "%d", kq);
                if (setenv("REGRESS_KQUEUE_FD", fdbuf, 1) == -1)
                        err(1, "setenv");
                if (setenv("REGRESS_KQUEUE_CLOEXEC",
                    cloexec ? "1" : "0", 1) == -1)
                        err(1, "setenv 2");
                execv(argv0, args);
                err(1, "execve");
        }
        if (waitpid(pid, &status, 0) == -1)
                err(1, "waitpid");
        if (status != 0)
                errx(1, "child failed");
}

static void
do_exec_child(void)
{
        char *arg;
        int cloexec, fd;

        arg = getenv("REGRESS_KQUEUE_FD");
        if (arg == NULL)
                errx(1, "fd arg is missing");
        fd = atoi(arg);

        arg = getenv("REGRESS_KQUEUE_CLOEXEC");
        if (arg != NULL && strcmp(arg, "1") == 0)
                cloexec = 1;
        else
                cloexec = 0;

        if (cloexec) {
                if (kevent(fd, NULL, 0, NULL, 0, 0) == -1) {
                        if (errno != EBADF)
                                err(1, "child after exec: kevent cloexec");
                } else {
                        errx(1, "child after exec: "
                            "kqueue cloexec fd is not closed");
                }
        } else {
                if (kevent(fd, NULL, 0, NULL, 0, 0) == -1) {
                        err(1, "child after exec: kevent");
                }
        }
}