src/lxc/freezer.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 #define _GNU_SOURCE
  24 #include <stdio.h>
  25 #undef _GNU_SOURCE
  26 #include <stdlib.h>
  27 #include <errno.h>
  28 #include <unistd.h>
  29 #include <string.h>
  30 #include <fcntl.h>
  31 #include <sys/types.h>
  32 #include <sys/param.h>
  33
  34 #include "error.h"
  35
  36 #include <lxc/log.h>
  37 #include <lxc/cgroup.h>
  38
  39 lxc_log_define(lxc_freezer, lxc);
  40
  41 static int freeze_unfreeze(const char *name, int freeze)
  42 {
  43         char *nsgroup;
  44         char freezer[MAXPATHLEN], *f;
  45         char tmpf[32];
  46         int fd, ret;
  47
  48         ret = lxc_cgroup_path_get(&nsgroup, "freezer", name);
  49         if (ret)
  50                 return -1;
  51
  52         ret = snprintf(freezer, MAXPATHLEN, "%s/freezer.state", nsgroup);
  53         if (ret >= MAXPATHLEN) {
  54                 ERROR("freezer.state name too long");
  55                 return -1;
  56         }
  57
  58         fd = open(freezer, O_RDWR);
  59         if (fd < 0) {
  60                 SYSERROR("failed to open freezer for '%s'", name);
  61                 return -1;
  62         }
  63
  64         if (freeze) {
  65                 f = "FROZEN";
  66                 ret = write(fd, f, strlen(f) + 1);
  67         } else {
  68                 f = "THAWED";
  69                 ret = write(fd, f, strlen(f) + 1);
  70
  71                 /* compatibility code with old freezer interface */
  72                 if (ret < 0) {
  73                         f = "RUNNING";
  74                         ret = write(fd, f, strlen(f) + 1) < 0;
  75                 }
  76         }
  77
  78         if (ret < 0) {
  79                 SYSERROR("failed to write '%s' to '%s'", f, freezer);
  80                 goto out;
  81         }
  82
  83         while (1) {
  84                 ret = lseek(fd, 0L, SEEK_SET);
  85                 if (ret < 0) {
  86                         SYSERROR("failed to lseek on file '%s'", freezer);
  87                         goto out;
  88                 }
  89
  90                 ret = read(fd, tmpf, sizeof(tmpf));
  91                 if (ret < 0) {
  92                         SYSERROR("failed to read to '%s'", freezer);
  93                         goto out;
  94                 }
  95
  96                 ret = strncmp(f, tmpf, strlen(f));
  97                 if (!ret)
  98                         break;          /* Success */
  99
 100                 sleep(1);
 101
 102                 ret = lseek(fd, 0L, SEEK_SET);
 103                 if (ret < 0) {
 104                         SYSERROR("failed to lseek on file '%s'", freezer);
 105                         goto out;
 106                 }
 107
 108                 ret = write(fd, f, strlen(f) + 1);
 109                 if (ret < 0) {
 110                         SYSERROR("failed to write '%s' to '%s'", f, freezer);
 111                         goto out;
 112                 }
 113         }
 114
 115 out:
 116         close(fd);
 117         return ret;
 118 }
 119
 120 int lxc_freeze(const char *name)
 121 {
 122         return freeze_unfreeze(name, 1);
 123 }
 124
 125 int lxc_unfreeze(const char *name)
 126 {
 127         return freeze_unfreeze(name, 0);
 128 }
 129