src/liblxc/monitor.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23 #include <stdio.h>
  24 #include <errno.h>
  25 #include <unistd.h>
  26 #include <string.h>
  27 #include <fcntl.h>
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <sys/param.h>
  31 #include <sys/inotify.h>
  32 #include <netinet/in.h>
  33 #include <net/if.h>
  34
  35 #include <lxc.h>
  36 #include <state.h>
  37 #include <log.h>
  38
  39 int lxc_monitor(const char *name, int output_fd)
  40 {
  41         char path[MAXPATHLEN];
  42         int err = -1, nfd, wfd, state;
  43
  44         nfd = inotify_init();
  45         if (nfd < 0) {
  46                 lxc_log_syserror("failed to initialize inotify");
  47                 return -1;
  48         }
  49
  50         snprintf(path, MAXPATHLEN, LXCPATH "/%s/state", name);
  51
  52         wfd = inotify_add_watch(nfd, path, IN_DELETE_SELF|IN_CLOSE_WRITE);
  53         if (wfd < 0) {
  54                 lxc_log_syserror("failed to add a watch on %s", path);
  55                 goto out;
  56         }
  57
  58         for(;;) {
  59                 struct inotify_event evt;
  60
  61                 if (read(nfd, &evt, sizeof(evt)) < 0) {
  62                         lxc_log_syserror("failed to read inotify event");
  63                         goto out;
  64                 }
  65
  66                 if (evt.mask & IN_CLOSE_WRITE) {
  67
  68                         state = lxc_getstate(name);
  69                         if (state < 0) {
  70                                 lxc_log_error("failed to get the state for %s",
  71                                               name);
  72                                 goto out;
  73                         }
  74
  75                         if (write(output_fd, &state, sizeof(state)) < 0) {
  76                                 lxc_log_syserror("failed to send state to %d",
  77                                                  output_fd);
  78                                 goto out;
  79                         }
  80                         continue;
  81                 }
  82
  83                 if (evt.mask & IN_DELETE_SELF) {
  84                         close(output_fd);
  85                         err = 0;
  86                         goto out;
  87                 }
  88
  89                 lxc_log_error("unknown evt for inotity (%d)", evt.mask);
  90                 goto out;
  91         }
  92
  93 out:
  94         inotify_rm_watch(nfd, wfd);
  95         close(nfd);
  96         return err;
  97 }