Add return error status in the different functions

[mirror_lxc.git] / src / lxc / monitor.c

/*
 * lxc: linux Container library
 *
 * (C) Copyright IBM Corp. 2007, 2008
 *
 * Authors:
 * Daniel Lezcano <dlezcano at fr.ibm.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/inotify.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>

#include "error.h"
#include <lxc/lxc.h>

#ifndef UNIX_PATH_MAX
#define UNIX_PATH_MAX 108
#endif

#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif

/* assuming this multicast group is not used by anyone else :/
 * otherwise a new genetlink family should be defined to own
 * its multicast groups */
#define MONITOR_MCGROUP RTNLGRP_MAX

int lxc_monitor(const char *name, int output_fd)
{
	char path[MAXPATHLEN];
	int err = -1, nfd, wfd, state;

	nfd = inotify_init();
	if (nfd < 0) {
		lxc_log_syserror("failed to initialize inotify");
		return -1;
	}

	snprintf(path, MAXPATHLEN, LXCPATH "/%s/state", name);

	wfd = inotify_add_watch(nfd, path, IN_DELETE_SELF|IN_CLOSE_WRITE);
	if (wfd < 0) {
		lxc_log_syserror("failed to add a watch on %s", path);
		goto out;
	}

	for(;;) {
		struct inotify_event evt;

		if (read(nfd, &evt, sizeof(evt)) < 0) {
			lxc_log_syserror("failed to read inotify event");
			goto out;
		}

		if (evt.mask & IN_CLOSE_WRITE) {

			state = lxc_getstate(name);
			if (state < 0) {
				lxc_log_error("failed to get the state for %s",
					      name);
				goto out;
			}

			if (write(output_fd, &state, sizeof(state)) < 0) {
				lxc_log_syserror("failed to send state to %d", 
						 output_fd);
				goto out;
			}
			continue;
		}

		if (evt.mask & IN_DELETE_SELF) {
			close(output_fd);
			err = 0;
			goto out;
		}

		lxc_log_error("unknown evt for inotity (%d)", evt.mask);
		goto out;
	}

out:
	inotify_rm_watch(nfd, wfd);
	close(nfd);
	return err;
}

static void lxc_monitor_send(struct lxc_msg *msg)
{
	int fd;
	struct sockaddr_nl addr;

	fd = socket(PF_NETLINK, SOCK_RAW, 0);
	if (fd < 0) {
		lxc_log_syserror("failed to create notification socket");
		return;
	}

	memset(&addr, 0, sizeof(addr));

	addr.nl_family = AF_NETLINK;
	addr.nl_pid = 0;
 	addr.nl_groups = MONITOR_MCGROUP;

	sendto(fd, msg, sizeof(*msg), 0,
	       (const struct sockaddr *)&addr, sizeof(addr));

	close(fd);
}

void lxc_monitor_send_state(const char *name, lxc_state_t state)
{
	struct lxc_msg msg = { .type = lxc_msg_state,
			       .value = state };
	strncpy(msg.name, name, sizeof(msg.name));

	lxc_monitor_send(&msg);
}

int lxc_monitor_open(void)
{
	int fd;
	struct sockaddr_nl addr;

	fd = socket(PF_NETLINK, SOCK_RAW, 0);
	if (fd < 0) {
		lxc_log_syserror("failed to create notification socket");
		return -LXC_ERROR_INTERNAL;
	}

	memset(&addr, 0, sizeof(addr));

	addr.nl_family = AF_NETLINK;
	addr.nl_pid = 0;
  	addr.nl_groups = MONITOR_MCGROUP;

	if (bind(fd, (const struct sockaddr *)&addr, sizeof(addr))) {
		lxc_log_syserror("failed to bind to multicast group '%d'",
			addr.nl_groups);
		close(fd);
		return -1;
	}

	return fd;
}

int lxc_monitor_read(int fd, struct lxc_msg *msg)
{
	struct sockaddr_nl from;
	socklen_t len = sizeof(from);
	int ret;

	ret = recvfrom(fd, msg, sizeof(*msg), 0, 
		       (struct sockaddr *)&from, &len);
	if (ret < 0) {
		lxc_log_syserror("failed to received state");
		return -LXC_ERROR_INTERNAL;
	}

	return ret;
}

int lxc_monitor_close(int fd)
{
	return close(fd);
}