[CONNECTOR]: Add userspace example code into Documentation/connector/

/*

 * 	ucon.c

 *

 * Copyright (c) 2004+ Evgeniy Polyakov <johnpol@2ka.mipt.ru>

 *

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

 */

#include <asm/types.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/poll.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <arpa/inet.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <errno.h>

#include <time.h>

#include <linux/connector.h>

#define DEBUG

#define NETLINK_CONNECTOR 	11

#ifdef DEBUG

#define ulog(f, a...) fprintf(stdout, f, ##a)

#else

#define ulog(f, a...) do {} while (0)

#endif

static int need_exit;

static __u32 seq;

static int netlink_send(int s, struct cn_msg *msg)

{

	struct nlmsghdr *nlh;

	unsigned int size;

	int err;

	char buf[128];

	struct cn_msg *m;

	size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len);

	nlh = (struct nlmsghdr *)buf;

	nlh->nlmsg_seq = seq++;

	nlh->nlmsg_pid = getpid();

	nlh->nlmsg_type = NLMSG_DONE;

	nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh));

	nlh->nlmsg_flags = 0;

	m = NLMSG_DATA(nlh);

#if 0

	ulog("%s: [%08x.%08x] len=%u, seq=%u, ack=%u.\n",

	       __func__, msg->id.idx, msg->id.val, msg->len, msg->seq, msg->ack);

#endif

	memcpy(m, msg, sizeof(*m) + msg->len);

	err = send(s, nlh, size, 0);

	if (err == -1)

		ulog("Failed to send: %s [%d].\n",

			strerror(errno), errno);

	return err;

}

int main(int argc, char *argv[])

{

	int s;

	char buf[1024];

	int len;

	struct nlmsghdr *reply;

	struct sockaddr_nl l_local;

	struct cn_msg *data;

	FILE *out;

	time_t tm;

	struct pollfd pfd;

	if (argc < 2)

		out = stdout;

	else {

		out = fopen(argv[1], "a+");

		if (!out) {

			ulog("Unable to open %s for writing: %s\n",

				argv[1], strerror(errno));

			out = stdout;

		}

	}

	memset(buf, 0, sizeof(buf));

	s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);

	if (s == -1) {

		perror("socket");

		return -1;

	}

	l_local.nl_family = AF_NETLINK;

	l_local.nl_groups = 0x123; /* bitmask of requested groups */

	l_local.nl_pid = 0;

	if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) {

		perror("bind");

		close(s);

		return -1;

	}

#if 0

	{

		int on = 0x57; /* Additional group number */

		setsockopt(s, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &on, sizeof(on));

	}

#endif

	if (0) {

		int i, j;

		memset(buf, 0, sizeof(buf));

		data = (struct cn_msg *)buf;

		data->id.idx = 0x123;

		data->id.val = 0x456;

		data->seq = seq++;

		data->ack = 0;

		data->len = 0;

		for (j=0; j<10; ++j) {

			for (i=0; i<1000; ++i) {

				len = netlink_send(s, data);

			}

			ulog("%d messages have been sent to %08x.%08x.\n", i, data->id.idx, data->id.val);

		}

		return 0;

	}

	pfd.fd = s;

	while (!need_exit) {

		pfd.events = POLLIN;

		pfd.revents = 0;

		switch (poll(&pfd, 1, -1)) {

			case 0:

				need_exit = 1;

				break;

			case -1:

				if (errno != EINTR) {

					need_exit = 1;

					break;

				}

				continue;

		}

		if (need_exit)

			break;

		memset(buf, 0, sizeof(buf));

		len = recv(s, buf, sizeof(buf), 0);

		if (len == -1) {

			perror("recv buf");

			close(s);

			return -1;

		}

		reply = (struct nlmsghdr *)buf;

		switch (reply->nlmsg_type) {

		case NLMSG_ERROR:

			fprintf(out, "Error message received.\n");

			fflush(out);

			break;

		case NLMSG_DONE:

			data = (struct cn_msg *)NLMSG_DATA(reply);

			time(&tm);

			fprintf(out, "%.24s : [%x.%x] [%08u.%08u].\n",

				ctime(&tm), data->id.idx, data->id.val, data->seq, data->ack);

			fflush(out);

			break;

		default:

			break;

		}

	}

	close(s);

	return 0;

}