view rust/chg/src/sendfds.c @ 42468:a3a8887e4426

rust: using policy.importrust from Python callers

This commit converts all current Python callers of
mercurial.rustext to the new policy.importrust system.

After this point, going through policy.importrust
or policy.importmod (in some more distant future)
is mandatory for callers of Rust code outside of
Python tests.

We felt it to be appropriate to keep Rust-specific tests
run inconditionally if the Rust extensions are present.

/*
 * Utility to send fds via Unix domain socket
 *
 * Copyright 2011, 2018 Yuya Nishihara <[e-mail]>
 *
 * This software may be used and distributed according to the terms of the
 * GNU General Public License version 2 or any later version.
 */

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>

#define MAX_FD_LEN 10

/*
 * Sends the given fds with 1-byte dummy payload.
 *
 * Returns the number of bytes sent on success, -1 on error and errno is set
 * appropriately.
 */
ssize_t sendfds(int sockfd, const int *fds, size_t fdlen)
{
	char dummy[1] = {0};
	struct iovec iov = {dummy, sizeof(dummy)};
	char fdbuf[CMSG_SPACE(sizeof(fds[0]) * MAX_FD_LEN)];
	struct msghdr msgh;
	struct cmsghdr *cmsg;

	/* just use a fixed-size buffer since we'll never send tons of fds */
	if (fdlen > MAX_FD_LEN) {
		errno = EINVAL;
		return -1;
	}

	memset(&msgh, 0, sizeof(msgh));
	msgh.msg_iov = &iov;
	msgh.msg_iovlen = 1;
	msgh.msg_control = fdbuf;
	msgh.msg_controllen = CMSG_SPACE(sizeof(fds[0]) * fdlen);

	cmsg = CMSG_FIRSTHDR(&msgh);
	cmsg->cmsg_level = SOL_SOCKET;
	cmsg->cmsg_type = SCM_RIGHTS;
	cmsg->cmsg_len = CMSG_LEN(sizeof(fds[0]) * fdlen);
	memcpy(CMSG_DATA(cmsg), fds, sizeof(fds[0]) * fdlen);
	msgh.msg_controllen = cmsg->cmsg_len;
	return sendmsg(sockfd, &msgh, 0);
}