src/lxc/lxc_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 <libgen.h>
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27
  28 #include <lxc.h>
  29 #include <state.h>
  30
  31 void usage(char *cmd)
  32 {
  33         fprintf(stderr, "%s <command>\n", basename(cmd));
  34         fprintf(stderr, "\t -n <name>   : name of the container\n");
  35         _exit(1);
  36 }
  37
  38 int main(int argc, char *argv[])
  39 {
  40         char opt;
  41         char *name = NULL;
  42         int fds[2];
  43         pid_t pid;
  44
  45         while ((opt = getopt(argc, argv, "n:")) != -1) {
  46                 switch (opt) {
  47                 case 'n':
  48                         name = optarg;
  49                         break;
  50                 }
  51         }
  52
  53         if (!name)
  54                 usage(argv[0]);
  55
  56         if (pipe(fds)) {
  57                 perror("pipe");
  58                 return 1;
  59         }
  60
  61         pid = fork();
  62         if (pid < 0) {
  63                 perror("fork");
  64                 return 1;
  65         }
  66
  67         if (!pid) {
  68                 close(fds[0]);
  69                 if (lxc_monitor(name, fds[1])) {
  70                         fprintf(stderr, "failed to monitor %s\n", name);
  71                         return 1;
  72                 }
  73
  74                 return 0;
  75         }
  76
  77         close(fds[1]);
  78
  79         for (;;) {
  80                 int err, state;
  81
  82                 err = read(fds[0], &state, sizeof(state));
  83                 if (err < 0) {
  84                         perror("read");
  85                         return 1;
  86                 }
  87
  88                 if (!err) {
  89                         printf("container has been destroyed\n");
  90                         return 0;
  91                 }
  92
  93                 printf("container has changed the state to %d - %s\n",
  94                        state, state2str(state));
  95         }
  96         return 0;
  97 }
  98