sortix-mirror/regress/test-unix-socket-fd-leak.c
Jonas 'Sortie' Termansen 3c43f71084 Implement file descriptor passing.
This change refactors the Unix socket / pipe backend to have a ring buffer
containing segments, where each segment has an optional leading ancillary
buffer containing control messages followed by a normal data buffer.

The SCM_RIGHTS control message has been implemented which transfers file
descriptors to the receiving process. File descriptors are reference counted
and cycles are prevented using the following restrictions:

1) Unix sockets cannot be sent on themselves (on either end).
2) Unix sockets themselves being sent cannot be sent on.
3) Unix sockets cannot send a Unix socket being sent on.

This is a compatible ABI change.
2021-12-31 22:24:11 +01:00

66 lines
1.8 KiB
C

/*
* Copyright (c) 2021 Jonas 'Sortie' Termansen.
*
* 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.
*
* test-unix-socket-fd-leak.c
* Tests whether leaking file descriptors over a Unix socket works.
*/
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <stdalign.h>
#include <stdio.h>
#include <unistd.h>
#include "test.h"
int main(void)
{
int fds[2];
test_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
FILE* file;
test_assert((file = tmpfile()));
struct msghdr mhdr;
char buf[1] = { 0 };
struct iovec iov;
iov.iov_base = buf;
iov.iov_len = sizeof(buf);
alignas(struct cmsghdr) char cmsgdata[CMSG_SPACE(sizeof(int))];
buf[0] = 'X';
memset(&mhdr, 0, sizeof(mhdr));
mhdr.msg_iov = &iov;
mhdr.msg_iovlen = 1;
mhdr.msg_control = cmsgdata;
mhdr.msg_controllen = sizeof(cmsgdata);
struct cmsghdr* cmsg = CMSG_FIRSTHDR(&mhdr);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
int* cdata = (int*) CMSG_DATA(cmsg);
*cdata = fileno(file);
ssize_t amount = sendmsg(fds[1], &mhdr, 0);
test_assert(0 <= amount);
test_assertx(amount == 1);
fclose(file);
close(fds[0]);
close(fds[1]);
return 0;
}