view rust/chg/src/sendfds.c @ 47142:4292bed8da7c

revlog: make the index always return the same tuple

It is simpler to manage the diferrence in on disk format in the internal index
code itself and lets the rest of the code always handle the same object.

This will become even more important when the data we store will be entirely
different (for example the changelog does not need the "linkrev" field.

We start with item reading, we will deal with item writing in the next
changesets.

Differential Revision: https://phab.mercurial-scm.org/D10568

/*
 * 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);
}