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/* $OpenBSD: mcontrol-stream.c,v 1.1 2018/12/19 21:21:59 bluhm Exp $ */
/*
* Copyright (c) 2018 Alexander Bluhm <bluhm@openbsd.org>
*
* 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/socket.h>
#include <sys/wait.h>
#include <err.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
pid_t pid;
int fd, s[2], status;
char str[] = "foo";
struct msghdr msg;
struct cmsghdr *cmsg;
union {
struct cmsghdr hdr;
unsigned char buf[CMSG_SPACE(sizeof(int))];
} cmsgbuf;
struct iovec io_vector[1];
if ((fd = open("/dev/null", O_RDONLY)) == -1)
err(1, "open");
if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) == -1)
err(1, "socketpair");
if ((pid = fork()) == -1)
err(1, "fork");
if (pid == 0) {
char buf[16];
ssize_t n;
/*
* The first recv(2) will block until the second control
* message causes a short read.
*/
if ((n = recv(s[1], buf, sizeof(buf), MSG_WAITALL)) == -1)
err(1, "recv 1");
if ((size_t)n != strlen(str))
errx(1, "recv 1: len %zd", n);
if ((n = recv(s[1], buf, sizeof(buf), 0)) == -1)
err(1, "recv 2");
if ((size_t)n != strlen(str))
errx(1, "recv 2: len %zd", n);
_exit(0);
}
io_vector[0].iov_base = str;
io_vector[0].iov_len = strlen(str);
memset(&msg, 0, sizeof(msg));
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
msg.msg_iov = io_vector;
msg.msg_iovlen = 1;
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
*(int *)CMSG_DATA(cmsg) = fd;
if (sendmsg(s[0], &msg, 0) == -1)
err(1, "sendmsg 1");
/* Wait until child is blocking in recv(2) MSG_WAITALL syscall. */
sleep(2);
/* This will insert a control mbuf while soreceive() is sleeping. */
if (sendmsg(s[0], &msg, 0) == -1)
err(1, "sendmsg 2");
if (close(s[0]) == -1)
err(1, "close");
if (waitpid(pid, &status, 0) == -1)
err(1, "waitpid");
if (status != 0)
errx(1, "child: %d", status);
return 0;
}
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