/*      $OpenBSD: kqueue-fdpass.c,v 1.3 2016/09/20 23:05:27 bluhm Exp $ */
/*
 *      Written by Philip Guenther <guenther@openbsd.org> 2011 Public Domain
 */

#include <sys/types.h>
#include <sys/event.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "main.h"

int
do_fdpass(void)
{
        struct msghdr msg;
        union {
                struct cmsghdr hdr;
                char buf[CMSG_SPACE(sizeof(int))];
        } cmsgbuf;
        struct kevent ke;
        struct cmsghdr *cmp;
        pid_t pid;
        int pfd[2], fd, status;

        ASS(socketpair(PF_LOCAL, SOCK_STREAM, 0, pfd) == 0,
            warn("socketpair"));

        pid = fork();
        if (pid == -1)
                err(1, "fork");
        if (pid == 0) {
                close(pfd[0]);

                /* a kqueue with event to pass */
                fd = kqueue();
                EV_SET(&ke, SIGHUP, EVFILT_SIGNAL, EV_ADD|EV_ENABLE,
                    0, 0, NULL);
                if (kevent(fd, &ke, 1, NULL, 0, NULL) != 0)
                        err(1, "can't register events on kqueue");

                memset(&cmsgbuf.buf, 0, sizeof cmsgbuf.buf);
                memset(&msg, 0, sizeof msg);
                msg.msg_control = &cmsgbuf.buf;
                msg.msg_controllen = sizeof(cmsgbuf);

                cmp = CMSG_FIRSTHDR(&msg);
                cmp->cmsg_len = CMSG_LEN(sizeof(int));
                cmp->cmsg_level = SOL_SOCKET;
                cmp->cmsg_type = SCM_RIGHTS;

                *(int *)CMSG_DATA(cmp) = fd;

                if (sendmsg(pfd[1], &msg, 0) == 0)
                        errx(1, "sendmsg succeeded when it shouldn't");
                if (errno != EINVAL)
                        err(1, "child sendmsg");
                printf("sendmsg failed with EINVAL as expected\n");
                close(pfd[1]);
                exit(0);
        }

        close(pfd[1]);
        wait(&status);
        close(pfd[0]);

        return (0);
}