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/* $OpenBSD: pass.c,v 1.1.1.1 2018/04/10 23:00:53 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 <string.h>
#include <unistd.h>
#include "header.h"
void
fdops(int fdpre, int fdpost)
{
struct msghdr msg;
struct iovec iov[1];
char buf[1];
struct cmsghdr *cmsg;
union {
struct cmsghdr hdr;
unsigned char buf[CMSG_SPACE(sizeof(int))];
} cmsgbuf;
pid_t child;
int pair[2], status;
if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) == -1)
err(1, "socketpair");
memset(&msg, 0, sizeof(msg));
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
if ((child = fork()) == -1)
err(1, "fork");
if (child == 0) {
/* child process */
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) = fdpre;
if (sendmsg(pair[1], &msg, 0) == -1)
err(1, "sendmsg pre");
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) = fdpost;
if (sendmsg(pair[1], &msg, 0) == -1)
err(1, "sendmsg post");
_exit(0);
}
/* parent process */
msg.msg_iov = iov;
msg.msg_iovlen = 1;
iov[0].iov_base = buf;
iov[0].iov_len = sizeof(buf);
if (recvmsg(pair[0], &msg, 0) == -1)
err(1, "recvmsg pre");
if ((msg.msg_flags & MSG_TRUNC) || (msg.msg_flags & MSG_CTRUNC))
errx(1, "trunk pre");
if (recvmsg(pair[0], &msg, 0) == -1)
err(1, "recvmsg post");
if ((msg.msg_flags & MSG_TRUNC) || (msg.msg_flags & MSG_CTRUNC))
errx(1, "trunk post");
if (waitpid(child, &status, 0) == -1)
err(1, "waitpid");
if (status != 0)
errx(1, "child failed: %d", status);
}
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