src/lxc/monitor.c

	monitor.c revision 31c53c2e1afc6c81ce4aad5ef4cb982cd2fea365
/*
 * 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 <sys/un.h>
#include <netinet/in.h>
#include <net/if.h>

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

lxc_log_define(lxc_monitor, lxc);

#ifndef UNIX_PATH_MAX
#define UNIX_PATH_MAX 108
#endif

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

    nfd = inotify_init();
    if (nfd < 0) {
        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) {
        SYSERROR("failed to add a watch on %s", path);
        goto out;
    }

    for(;;) {
        struct inotify_event evt;

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

        if (evt.mask & IN_CLOSE_WRITE) {

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

            if (write(output_fd, &state, sizeof(state)) < 0) {
                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;
        }

        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_un addr = { .sun_family = AF_UNIX };
    char *offset = &addr.sun_path[1];

    strcpy(offset, "lxc-monitor");

    fd = socket(PF_UNIX, SOCK_DGRAM, 0);
    if (fd < 0)
        return;

    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)
{
    struct sockaddr_un addr = { .sun_family = AF_UNIX };
    char *offset = &addr.sun_path[1];
    int fd;

    strcpy(offset, "lxc-monitor");

    fd = socket(PF_UNIX, SOCK_DGRAM, 0);
    if (fd < 0)
        return -1;

    if (bind(fd, (struct sockaddr *)&addr, sizeof(addr))) {
        close(fd);
        return -1;
    }

    return fd;
}

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

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

    return ret;
}

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