commands: make state server interface flexible

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

/* liblxcapi
 *
 * Copyright © 2017 Christian Brauner <christian.brauner@ubuntu.com>.
 * Copyright © 2017 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2, as
 * published by the Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>

#include "commands.h"
#include "commands_utils.h"
#include "log.h"
#include "monitor.h"
#include "state.h"

lxc_log_define(lxc_commands_utils, lxc);

int lxc_cmd_sock_rcv_state(int state_client_fd, int timeout)
{
	int ret;
	struct lxc_msg msg;
	struct timeval out;

	memset(&out, 0, sizeof(out));
	out.tv_sec = timeout;
	ret = setsockopt(state_client_fd, SOL_SOCKET, SO_RCVTIMEO,
			 (const void *)&out, sizeof(out));
	if (ret < 0) {
		SYSERROR("Failed to set %ds timeout on containter state socket", timeout);
		return -1;
	}

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

again:
	ret = recv(state_client_fd, &msg, sizeof(msg), 0);
	if (ret < 0) {
		if (errno == EINTR)
			goto again;

		ERROR("failed to receive message: %s", strerror(errno));
		return -1;
	}

	if (ret == 0) {
		ERROR("length of message was 0");
		return -1;
	}

	TRACE("received state %s from state client %d",
	      lxc_state2str(msg.value), state_client_fd);

	return msg.value;
}

/* Register a new state client and retrieve state from command socket. */
int lxc_cmd_sock_get_state(const char *name, const char *lxcpath,
			   lxc_state_t states[MAX_STATE], int timeout)
{
	int ret;
	int state_client_fd;

	ret = lxc_cmd_add_state_client(name, lxcpath, states, &state_client_fd);
	if (ret < 0)
		return -1;

	if (ret < MAX_STATE)
		return ret;

	ret = lxc_cmd_sock_rcv_state(state_client_fd, timeout);
	close(state_client_fd);
	return ret;
}