src/lxc/cgroup.h

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23 #ifndef _ncgroup_h
  24 #define _ncgroup_h
  25 #include <stdbool.h>
  26 #include <stdint.h>
  27 #include <stddef.h>
  28
  29 struct cgroup_hierarchy;
  30 struct cgroup_meta_data;
  31 struct cgroup_mount_point;
  32
  33 /*
  34  * cgroup_meta_data: the metadata about the cgroup infrastructure on this
  35  *                   host
  36  */
  37 struct cgroup_meta_data {
  38         ptrdiff_t ref; /* simple refcount */
  39         struct cgroup_hierarchy **hierarchies;
  40         struct cgroup_mount_point **mount_points;
  41         int maximum_hierarchy;
  42 };
  43
  44 /*
  45  * cgroup_hierarchy: describes a single cgroup hierarchy
  46  *                   (may have multiple mount points)
  47  */
  48 struct cgroup_hierarchy {
  49         int index;
  50         bool used; /* false if the hierarchy should be ignored by lxc */
  51         char **subsystems;
  52         struct cgroup_mount_point *rw_absolute_mount_point;
  53         struct cgroup_mount_point *ro_absolute_mount_point;
  54         struct cgroup_mount_point **all_mount_points;
  55         size_t all_mount_point_capacity;
  56 };
  57
  58 /*
  59  * cgroup_mount_point: a mount point to where a hierarchy
  60  *                     is mounted to
  61  */
  62 struct cgroup_mount_point {
  63         struct cgroup_hierarchy *hierarchy;
  64         char *mount_point;
  65         char *mount_prefix;
  66         bool read_only;
  67 };
  68
  69 /*
  70  * cgroup_process_info: describes the membership of a
  71  *                      process to the different cgroup
  72  *                      hierarchies
  73  */
  74 struct cgroup_process_info {
  75         struct cgroup_process_info *next;
  76         struct cgroup_meta_data *meta_ref;
  77         struct cgroup_hierarchy *hierarchy;
  78         char *cgroup_path;
  79         char *cgroup_path_sub;
  80         char **created_paths;
  81         size_t created_paths_capacity;
  82         size_t created_paths_count;
  83         struct cgroup_mount_point *designated_mount_point;
  84 };
  85
  86 /* meta data management:
  87  *    lxc_cgroup_load_meta  loads the meta data (using subsystem
  88  *                          whitelist from main lxc configuration)
  89  *    lxc_cgroup_load_meta2 does the same, but allows one to specify
  90  *                          a custom whitelist
  91  *    lxc_cgroup_get_meta   increments the refcount of a meta data
  92  *                          object
  93  *    lxc_cgroup_put_meta   decrements the refcount of a meta data
  94  *                          object, potentially destroying it
  95  */
  96 extern struct cgroup_meta_data *lxc_cgroup_load_meta();
  97 extern struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist);
  98 extern struct cgroup_meta_data *lxc_cgroup_get_meta(struct cgroup_meta_data *meta_data);
  99 extern struct cgroup_meta_data *lxc_cgroup_put_meta(struct cgroup_meta_data *meta_data);
 100
 101 /* find the hierarchy corresponding to a given subsystem */
 102 extern struct cgroup_hierarchy *lxc_cgroup_find_hierarchy(struct cgroup_meta_data *meta_data, const char *subsystem);
 103
 104 /* find a mount point for a given hierarchy that has access to the cgroup in 'cgroup' and (if wanted) is writable */
 105 extern struct cgroup_mount_point *lxc_cgroup_find_mount_point(struct cgroup_hierarchy *hierarchy, const char *group, bool should_be_writable);
 106
 107 /* all-in-one: find a mount point for a given hierarchy that has access to the cgroup and return the correct path within */
 108 extern char *lxc_cgroup_find_abs_path(const char *subsystem, const char *group, bool should_be_writable, const char *suffix);
 109
 110 /* determine the cgroup membership of a given process */
 111 extern struct cgroup_process_info *lxc_cgroup_process_info_get(pid_t pid, struct cgroup_meta_data *meta);
 112 extern struct cgroup_process_info *lxc_cgroup_process_info_get_init(struct cgroup_meta_data *meta);
 113 extern struct cgroup_process_info *lxc_cgroup_process_info_get_self(struct cgroup_meta_data *meta);
 114
 115 /* create a new cgroup */
 116 extern struct cgroup_process_info *lxc_cgroup_create(const char *name, const char *path_pattern, struct cgroup_meta_data *meta_data, const char *sub_pattern);
 117 extern int lxc_cgroup_create_legacy(struct cgroup_process_info *base_info, const char *name, pid_t pid);
 118
 119 /* get the cgroup membership of a given container */
 120 extern struct cgroup_process_info *lxc_cgroup_get_container_info(const char *name, const char *lxcpath, struct cgroup_meta_data *meta_data);
 121
 122 /* move a processs to the cgroups specified by the membership */
 123 extern int lxc_cgroup_enter(struct cgroup_process_info *info, pid_t pid, bool enter_sub);
 124
 125 /* free process membership information */
 126 extern void lxc_cgroup_process_info_free(struct cgroup_process_info *info);
 127 extern void lxc_cgroup_process_info_free_and_remove(struct cgroup_process_info *info);
 128
 129 struct lxc_handler;
 130 extern char *lxc_cgroup_get_hierarchy_path_handler(const char *subsystem, struct lxc_handler *handler);
 131 extern char *lxc_cgroup_get_hierarchy_path(const char *subsystem, const char *name, const char *lxcpath);
 132 extern char *lxc_cgroup_get_hierarchy_abs_path_handler(const char *subsystem, struct lxc_handler *handler);
 133 extern char *lxc_cgroup_get_hierarchy_abs_path(const char *subsystem, const char *name, const char *lxcpath);
 134 extern int lxc_cgroup_set_handler(const char *filename, const char *value, struct lxc_handler *handler);
 135 extern int lxc_cgroup_get_handler(const char *filename, char *value, size_t len, struct lxc_handler *handler);
 136 extern int lxc_cgroup_set(const char *filename, const char *value, const char *name, const char *lxcpath);
 137 extern int lxc_cgroup_get(const char *filename, char *value, size_t len, const char *name, const char *lxcpath);
 138
 139 /*
 140  * lxc_cgroup_path_get: Get the absolute pathname for a cgroup
 141  * file for a running container.
 142  *
 143  * @filename  : the file of interest (e.g. "freezer.state") or
 144  *              the subsystem name (e.g. "freezer") in which case
 145  *              the directory where the cgroup may be modified
 146  *              will be returned
 147  * @name      : name of container to connect to
 148  * @lxcpath   : the lxcpath in which the container is running
 149  *
 150  * This is the exported function, which determines cgpath from the
 151  * lxc-start of the @name container running in @lxcpath.
 152  *
 153  * Returns path on success, NULL on error. The caller must free()
 154  * the returned path.
 155  */
 156 extern char *lxc_cgroup_path_get(const char *subsystem, const char *name,
 157                                  const char *lxcpath);
 158
 159 struct lxc_list;
 160 extern int lxc_setup_cgroup_without_devices(struct lxc_handler *h, struct lxc_list *cgroup_settings);
 161 extern int lxc_setup_cgroup_devices(struct lxc_handler *h, struct lxc_list *cgroup_settings);
 162
 163 extern int lxc_setup_mount_cgroup(const char *root, struct cgroup_process_info *base_info);
 164
 165 extern int lxc_cgroup_nrtasks_handler(struct lxc_handler *handler);
 166
 167 #endif