cgmanager: chown cgroups to the container root

[mirror_lxc.git] / src / lxc / cgroup.c

/*
 * lxc: linux Container library
 *
 * (C) Copyright IBM Corp. 2007, 2008
 *
 * Authors:
 * Daniel Lezcano <daniel.lezcano at free.fr>
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#define _GNU_SOURCE
#include <stdio.h>
#undef _GNU_SOURCE
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/inotify.h>
#include <sys/mount.h>
#include <netinet/in.h>
#include <net/if.h>

#include "error.h"
#include "config.h"
#include "commands.h"
#include "list.h"
#include "conf.h"
#include "utils.h"
#include "bdev.h"
#include "log.h"
#include "cgroup.h"
#include "start.h"
#include "state.h"

#if IS_BIONIC
#include <../include/lxcmntent.h>
#else
#include <mntent.h>
#endif

lxc_log_define(lxc_cgroup, lxc);

static struct cgroup_process_info *lxc_cgroup_process_info_getx(const char *proc_pid_cgroup_str, struct cgroup_meta_data *meta);
static char **subsystems_from_mount_options(const char *mount_options, char **kernel_list);
static void lxc_cgroup_mount_point_free(struct cgroup_mount_point *mp);
static void lxc_cgroup_hierarchy_free(struct cgroup_hierarchy *h);
static bool is_valid_cgroup(const char *name);
static int create_cgroup(struct cgroup_mount_point *mp, const char *path);
static int remove_cgroup(struct cgroup_mount_point *mp, const char *path, bool recurse);
static char *cgroup_to_absolute_path(struct cgroup_mount_point *mp, const char *path, const char *suffix);
static struct cgroup_process_info *find_info_for_subsystem(struct cgroup_process_info *info, const char *subsystem);
static int do_cgroup_get(const char *cgroup_path, const char *sub_filename, char *value, size_t len);
static int do_cgroup_set(const char *cgroup_path, const char *sub_filename, const char *value);
static bool cgroup_devices_has_allow_or_deny(struct lxc_handler *h, char *v, bool for_allow);
static int do_setup_cgroup_limits(struct lxc_handler *h, struct lxc_list *cgroup_settings, bool do_devices);
static int cgroup_recursive_task_count(const char *cgroup_path);
static int count_lines(const char *fn);
static int handle_cgroup_settings(struct cgroup_mount_point *mp, char *cgroup_path);

static struct cgroup_ops cgfs_ops;
struct cgroup_ops *active_cg_ops = &cgfs_ops;
static void init_cg_ops(void);

#ifdef HAVE_CGMANAGER
/* this needs to be mutexed for api use */
extern bool cgmanager_initialized;
extern bool use_cgmanager;
extern bool lxc_init_cgmanager(void);
#else
static bool cgmanager_initialized = false;
static bool use_cgmanager = false;
static bool lxc_init_cgmanager(void) { return false; }
#endif

static int cgroup_rmdir(char *dirname)
{
        struct dirent dirent, *direntp;
        int saved_errno = 0;
        DIR *dir;
        int ret, failed=0;
        char pathname[MAXPATHLEN];

        dir = opendir(dirname);
        if (!dir) {
                ERROR("%s: failed to open %s", __func__, dirname);
                return -1;
        }

        while (!readdir_r(dir, &dirent, &direntp)) {
                struct stat mystat;
                int rc;

                if (!direntp)
                        break;

                if (!strcmp(direntp->d_name, ".") ||
                    !strcmp(direntp->d_name, ".."))
                        continue;

                rc = snprintf(pathname, MAXPATHLEN, "%s/%s", dirname, direntp->d_name);
                if (rc < 0 || rc >= MAXPATHLEN) {
                        ERROR("pathname too long");
                        failed=1;
                        if (!saved_errno)
                                saved_errno = -ENOMEM;
                        continue;
                }
                ret = lstat(pathname, &mystat);
                if (ret) {
                        SYSERROR("%s: failed to stat %s", __func__, pathname);
                        failed=1;
                        if (!saved_errno)
                                saved_errno = errno;
                        continue;
                }
                if (S_ISDIR(mystat.st_mode)) {
                        if (cgroup_rmdir(pathname) < 0) {
                                if (!saved_errno)
                                        saved_errno = errno;
                                failed=1;
                        }
                }
        }

        if (rmdir(dirname) < 0) {
                SYSERROR("%s: failed to delete %s", __func__, dirname);
                if (!saved_errno)
                        saved_errno = errno;
                failed=1;
        }

        ret = closedir(dir);
        if (ret) {
                SYSERROR("%s: failed to close directory %s", __func__, dirname);
                if (!saved_errno)
                        saved_errno = errno;
                failed=1;
        }

        errno = saved_errno;
        return failed ? -1 : 0;
}

struct cgroup_meta_data *lxc_cgroup_load_meta()
{
        const char *cgroup_use = NULL;
        char **cgroup_use_list = NULL;
        struct cgroup_meta_data *md = NULL;
        int saved_errno;

        errno = 0;
        cgroup_use = lxc_global_config_value("lxc.cgroup.use");
        if (!cgroup_use && errno != 0)
                return NULL;
        if (cgroup_use) {
                cgroup_use_list = lxc_string_split_and_trim(cgroup_use, ',');
                if (!cgroup_use_list)
                        return NULL;
        }

        md = lxc_cgroup_load_meta2((const char **)cgroup_use_list);
        saved_errno = errno;
        lxc_free_array((void **)cgroup_use_list, free);
        errno = saved_errno;
        return md;
}

/* Step 1: determine all kernel subsystems */
bool find_cgroup_subsystems(char ***kernel_subsystems)
{
        FILE *proc_cgroups;
        bool bret = false;
        char *line = NULL;
        size_t sz = 0;
        size_t kernel_subsystems_count = 0;
        size_t kernel_subsystems_capacity = 0;
        int r;

        proc_cgroups = fopen_cloexec("/proc/cgroups", "r");
        if (!proc_cgroups)
                return false;

        while (getline(&line, &sz, proc_cgroups) != -1) {
                char *tab1;
                char *tab2;
                int hierarchy_number;

                if (line[0] == '#')
                        continue;
                if (!line[0])
                        continue;

                tab1 = strchr(line, '\t');
                if (!tab1)
                        continue;
                *tab1++ = '\0';
                tab2 = strchr(tab1, '\t');
                if (!tab2)
                        continue;
                *tab2 = '\0';

                tab2 = NULL;
                hierarchy_number = strtoul(tab1, &tab2, 10);
                if (!tab2 || *tab2)
                        continue;
                (void)hierarchy_number;

                r = lxc_grow_array((void ***)kernel_subsystems, &kernel_subsystems_capacity, kernel_subsystems_count + 1, 12);
                if (r < 0)
                        goto out;
                (*kernel_subsystems)[kernel_subsystems_count] = strdup(line);
                if (!(*kernel_subsystems)[kernel_subsystems_count])
                        goto out;
                kernel_subsystems_count++;
        }
        bret = true;

out:
        fclose(proc_cgroups);
        free(line);
        return bret;
}

/* Step 2: determine all hierarchies (by reading /proc/self/cgroup),
 *         since mount points don't specify hierarchy number and
 *         /proc/cgroups does not contain named hierarchies
 */
static bool find_cgroup_hierarchies(struct cgroup_meta_data *meta_data,
        bool all_kernel_subsystems, bool all_named_subsystems,
        const char **subsystem_whitelist)
{
        FILE *proc_self_cgroup;
        char *line = NULL;
        size_t sz = 0;
        int r;
        bool bret = false;
        size_t hierarchy_capacity = 0;

        proc_self_cgroup = fopen_cloexec("/proc/self/cgroup", "r");
        /* if for some reason (because of setns() and pid namespace for example),
         * /proc/self is not valid, we try /proc/1/cgroup... */
        if (!proc_self_cgroup)
                proc_self_cgroup = fopen_cloexec("/proc/1/cgroup", "r");
        if (!proc_self_cgroup)
                return false;

        while (getline(&line, &sz, proc_self_cgroup) != -1) {
                /* file format: hierarchy:subsystems:group,
                 * we only extract hierarchy and subsystems
                 * here */
                char *colon1;
                char *colon2;
                int hierarchy_number;
                struct cgroup_hierarchy *h = NULL;
                char **p;

                if (!line[0])
                        continue;

                colon1 = strchr(line, ':');
                if (!colon1)
                        continue;
                *colon1++ = '\0';
                colon2 = strchr(colon1, ':');
                if (!colon2)
                        continue;
                *colon2 = '\0';

                colon2 = NULL;
                hierarchy_number = strtoul(line, &colon2, 10);
                if (!colon2 || *colon2)
                        continue;

                if (hierarchy_number > meta_data->maximum_hierarchy) {
                        /* lxc_grow_array will never shrink, so even if we find a lower
                        * hierarchy number here, the array will never be smaller
                        */
                        r = lxc_grow_array((void ***)&meta_data->hierarchies, &hierarchy_capacity, hierarchy_number + 1, 12);
                        if (r < 0)
                                goto out;

                        meta_data->maximum_hierarchy = hierarchy_number;
                }

                /* this shouldn't happen, we had this already */
                if (meta_data->hierarchies[hierarchy_number])
                        goto out;

                h = calloc(1, sizeof(struct cgroup_hierarchy));
                if (!h)
                        goto out;

                meta_data->hierarchies[hierarchy_number] = h;

                h->index = hierarchy_number;
                h->subsystems = lxc_string_split_and_trim(colon1, ',');
                if (!h->subsystems)
                        goto out;
                /* see if this hierarchy should be considered */
                if (!all_kernel_subsystems || !all_named_subsystems) {
                        for (p = h->subsystems; *p; p++) {
                                if (!strncmp(*p, "name=", 5)) {
                                        if (all_named_subsystems || (subsystem_whitelist && lxc_string_in_array(*p, subsystem_whitelist))) {
                                                h->used = true;
                                                break;
                                        }
                                } else {
                                        if (all_kernel_subsystems || (subsystem_whitelist && lxc_string_in_array(*p, subsystem_whitelist))) {
                                                h->used = true;
                                                break;
                                        }
                                }
                        }
                } else {
                        /* we want all hierarchy anyway */
                        h->used = true;
                }
        }
        bret = true;

out:
        fclose(proc_self_cgroup);
        free(line);
        return bret;
}

/* Step 3: determine all mount points of each hierarchy */
static bool find_hierarchy_mountpts( struct cgroup_meta_data *meta_data, char **kernel_subsystems)
{
        bool bret = false;
        FILE *proc_self_mountinfo;
        char *line = NULL;
        size_t sz = 0;
        char **tokens = NULL;
        size_t mount_point_count = 0;
        size_t mount_point_capacity = 0;
        size_t token_capacity = 0;
        int r;

        proc_self_mountinfo = fopen_cloexec("/proc/self/mountinfo", "r");
        /* if for some reason (because of setns() and pid namespace for example),
         * /proc/self is not valid, we try /proc/1/cgroup... */
        if (!proc_self_mountinfo)
                proc_self_mountinfo = fopen_cloexec("/proc/1/mountinfo", "r");
        if (!proc_self_mountinfo)
                return false;

        while (getline(&line, &sz, proc_self_mountinfo) != -1) {
                char *token, *line_tok, *saveptr = NULL;
                size_t i, j, k;
                struct cgroup_mount_point *mount_point;
                struct cgroup_hierarchy *h;
                char **subsystems;

                if (line[0] && line[strlen(line) - 1] == '\n')
                        line[strlen(line) - 1] = '\0';

                for (i = 0, line_tok = line; (token = strtok_r(line_tok, " ", &saveptr)); line_tok = NULL) {
                        r = lxc_grow_array((void ***)&tokens, &token_capacity, i + 1, 64);
                        if (r < 0)
                                goto out;
                        tokens[i++] = token;
                }

                /* layout of /proc/self/mountinfo:
                 *      0: id
                 *      1: parent id
                 *      2: device major:minor
                 *      3: mount prefix
                 *      4: mount point
                 *      5: per-mount options
                 *    [optional X]: additional data
                 *    X+7: "-"
                 *    X+8: type
                 *    X+9: source
                 *    X+10: per-superblock options
                 */
                for (j = 6; j < i && tokens[j]; j++)
                        if (!strcmp(tokens[j], "-"))
                                break;

                /* could not find separator */
                if (j >= i || !tokens[j])
                        continue;
                /* there should be exactly three fields after
                 * the separator
                 */
                if (i != j + 4)
                        continue;

                /* not a cgroup filesystem */
                if (strcmp(tokens[j + 1], "cgroup") != 0)
                        continue;

                subsystems = subsystems_from_mount_options(tokens[j + 3], kernel_subsystems);
                if (!subsystems)
                        goto out;

                h = NULL;
                for (k = 1; k <= meta_data->maximum_hierarchy; k++) {
                        if (meta_data->hierarchies[k] &&
                            meta_data->hierarchies[k]->subsystems[0] &&
                            lxc_string_in_array(meta_data->hierarchies[k]->subsystems[0], (const char **)subsystems)) {
                                /* TODO: we could also check if the lists really match completely,
                                 *       just to have an additional sanity check */
                                h = meta_data->hierarchies[k];
                                break;
                        }
                }
                lxc_free_array((void **)subsystems, free);

                r = lxc_grow_array((void ***)&meta_data->mount_points, &mount_point_capacity, mount_point_count + 1, 12);
                if (r < 0)
                        goto out;

                /* create mount point object */
                mount_point = calloc(1, sizeof(*mount_point));
                if (!mount_point)
                        goto out;

                meta_data->mount_points[mount_point_count++] = mount_point;

                mount_point->hierarchy = h;
                mount_point->mount_point = strdup(tokens[4]);
                mount_point->mount_prefix = strdup(tokens[3]);
                if (!mount_point->mount_point || !mount_point->mount_prefix)
                        goto out;
                mount_point->read_only = !lxc_string_in_list("rw", tokens[5], ',');

                if (!strcmp(mount_point->mount_prefix, "/")) {
                        if (mount_point->read_only) {
                                if (!h->ro_absolute_mount_point)
                                        h->ro_absolute_mount_point = mount_point;
                        } else {
                                if (!h->rw_absolute_mount_point)
                                        h->rw_absolute_mount_point = mount_point;
                        }
                }

                k = lxc_array_len((void **)h->all_mount_points);
                r = lxc_grow_array((void ***)&h->all_mount_points, &h->all_mount_point_capacity, k + 1, 4);
                if (r < 0)
                        goto out;
                h->all_mount_points[k] = mount_point;
        }
        bret = true;

out:
        fclose(proc_self_mountinfo);
        free(tokens);
        free(line);
        return bret;
}

struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
{
        bool all_kernel_subsystems = true;
        bool all_named_subsystems = false;
        struct cgroup_meta_data *meta_data = NULL;
        char **kernel_subsystems = NULL;
        int saved_errno = 0;

        /* if the subsystem whitelist is not specified, include all
         * hierarchies that contain kernel subsystems by default but
         * no hierarchies that only contain named subsystems
         *
         * if it is specified, the specifier @all will select all
         * hierarchies, @kernel will select all hierarchies with
         * kernel subsystems and @named will select all named
         * hierarchies
         */
        all_kernel_subsystems = subsystem_whitelist ?
                (lxc_string_in_array("@kernel", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
                true;
        all_named_subsystems = subsystem_whitelist ?
                (lxc_string_in_array("@named", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
                false;

        meta_data = calloc(1, sizeof(struct cgroup_meta_data));
        if (!meta_data)
                return NULL;
        meta_data->ref = 1;

        if (!find_cgroup_subsystems(&kernel_subsystems))
                goto out_error;

        if (!find_cgroup_hierarchies(meta_data, all_kernel_subsystems,
                                all_named_subsystems, subsystem_whitelist))
                goto out_error;

        if (!find_hierarchy_mountpts(meta_data, kernel_subsystems))
                goto out_error;

        /* oops, we couldn't find anything */
        if (!meta_data->hierarchies || !meta_data->mount_points) {
                errno = EINVAL;
                goto out_error;
        }

        lxc_free_array((void **)kernel_subsystems, free);
        return meta_data;

out_error:
        saved_errno = errno;
        lxc_free_array((void **)kernel_subsystems, free);
        lxc_cgroup_put_meta(meta_data);
        errno = saved_errno;
        return NULL;
}

struct cgroup_meta_data *lxc_cgroup_get_meta(struct cgroup_meta_data *meta_data)
{
        meta_data->ref++;
        return meta_data;
}

struct cgroup_meta_data *lxc_cgroup_put_meta(struct cgroup_meta_data *meta_data)
{
        size_t i;
        if (!meta_data)
                return NULL;
        if (--meta_data->ref > 0)
                return meta_data;
        lxc_free_array((void **)meta_data->mount_points, (lxc_free_fn)lxc_cgroup_mount_point_free);
        if (meta_data->hierarchies) {
                for (i = 0; i <= meta_data->maximum_hierarchy; i++)
                        lxc_cgroup_hierarchy_free(meta_data->hierarchies[i]);
        }
        free(meta_data->hierarchies);
        free(meta_data);
        return NULL;
}

struct cgroup_hierarchy *lxc_cgroup_find_hierarchy(struct cgroup_meta_data *meta_data, const char *subsystem)
{
        size_t i;
        for (i = 0; i <= meta_data->maximum_hierarchy; i++) {
                struct cgroup_hierarchy *h = meta_data->hierarchies[i];
                if (h && lxc_string_in_array(subsystem, (const char **)h->subsystems))
                        return h;
        }
        return NULL;
}

struct cgroup_mount_point *lxc_cgroup_find_mount_point(struct cgroup_hierarchy *hierarchy, const char *group, bool should_be_writable)
{
        struct cgroup_mount_point **mps;
        struct cgroup_mount_point *current_result = NULL;
        ssize_t quality = -1;

        /* trivial case */
        if (hierarchy->rw_absolute_mount_point)
                return hierarchy->rw_absolute_mount_point;
        if (!should_be_writable && hierarchy->ro_absolute_mount_point)
                return hierarchy->ro_absolute_mount_point;

        for (mps = hierarchy->all_mount_points; mps && *mps; mps++) {
                struct cgroup_mount_point *mp = *mps;
                size_t prefix_len = mp->mount_prefix ? strlen(mp->mount_prefix) : 0;

                if (prefix_len == 1 && mp->mount_prefix[0] == '/')
                        prefix_len = 0;

                if (should_be_writable && mp->read_only)
                        continue;

                if (!prefix_len ||
                    (strncmp(group, mp->mount_prefix, prefix_len) == 0 &&
                     (group[prefix_len] == '\0' || group[prefix_len] == '/'))) {
                        /* search for the best quality match, i.e. the match with the
                         * shortest prefix where this group is still contained
                         */
                        if (quality == -1 || prefix_len < quality) {
                                current_result = mp;
                                quality = prefix_len;
                        }
                }
        }

        if (!current_result)
                errno = ENOENT;
        return current_result;
}

char *lxc_cgroup_find_abs_path(const char *subsystem, const char *group, bool should_be_writable, const char *suffix)
{
        struct cgroup_meta_data *meta_data;
        struct cgroup_hierarchy *h;
        struct cgroup_mount_point *mp;
        char *result;
        int saved_errno;

        meta_data = lxc_cgroup_load_meta();
        if (!meta_data)
                return NULL;

        h = lxc_cgroup_find_hierarchy(meta_data, subsystem);
        if (!h)
                goto out_error;

        mp = lxc_cgroup_find_mount_point(h, group, should_be_writable);
        if (!mp)
                goto out_error;

        result = cgroup_to_absolute_path(mp, group, suffix);
        if (!result)
                goto out_error;

        lxc_cgroup_put_meta(meta_data);
        return result;

out_error:
        saved_errno = errno;
        lxc_cgroup_put_meta(meta_data);
        errno = saved_errno;
        return NULL;
}

struct cgroup_process_info *lxc_cgroup_process_info_get(pid_t pid, struct cgroup_meta_data *meta)
{
        char pid_buf[32];
        snprintf(pid_buf, 32, "/proc/%lu/cgroup", (unsigned long)pid);
        return lxc_cgroup_process_info_getx(pid_buf, meta);
}

struct cgroup_process_info *lxc_cgroup_process_info_get_init(struct cgroup_meta_data *meta)
{
        return lxc_cgroup_process_info_get(1, meta);
}

struct cgroup_process_info *lxc_cgroup_process_info_get_self(struct cgroup_meta_data *meta)
{
        struct cgroup_process_info *i;
        i = lxc_cgroup_process_info_getx("/proc/self/cgroup", meta);
        if (!i)
                i = lxc_cgroup_process_info_get(getpid(), meta);
        return i;
}

/*
 * If a controller has ns cgroup mounted, then in that cgroup the handler->pid
 * is already in a new cgroup named after the pid.  'mnt' is passed in as
 * the full current cgroup.  Say that is /sys/fs/cgroup/lxc/2975 and the container
 * name is c1. .  We want to rename the cgroup directory to /sys/fs/cgroup/lxc/c1,
 * and return the string /sys/fs/cgroup/lxc/c1.
 */
static char *cgroup_rename_nsgroup(const char *mountpath, const char *oldname, pid_t pid, const char *name)
{
        char *dir, *fulloldpath;
        char *newname, *fullnewpath;
        int len, newlen, ret;

        /*
         * if cgroup is mounted at /cgroup and task is in cgroup /ab/, pid 2375 and
         * name is c1,
         * dir: /ab
         * fulloldpath = /cgroup/ab/2375
         * fullnewpath = /cgroup/ab/c1
         * newname = /ab/c1
         */
        dir = alloca(strlen(oldname) + 1);
        strcpy(dir, oldname);

        len = strlen(oldname) + strlen(mountpath) + 22;
        fulloldpath = alloca(len);
        ret = snprintf(fulloldpath, len, "%s/%s/%ld", mountpath, oldname, (unsigned long)pid);
        if (ret < 0 || ret >= len)
                return NULL;

        len = strlen(dir) + strlen(name) + 2;
        newname = malloc(len);
        if (!newname) {
                SYSERROR("Out of memory");
                return NULL;
        }
        ret = snprintf(newname, len, "%s/%s", dir, name);
        if (ret < 0 || ret >= len) {
                free(newname);
                return NULL;
        }

        newlen = strlen(mountpath) + len + 2;
        fullnewpath = alloca(newlen);
        ret = snprintf(fullnewpath, newlen, "%s/%s", mountpath, newname);
        if (ret < 0 || ret >= newlen) {
                free(newname);
                return NULL;
        }

        if (access(fullnewpath, F_OK) == 0) {
                if (rmdir(fullnewpath) != 0) {
                        SYSERROR("container cgroup %s already exists.", fullnewpath);
                        free(newname);
                        return NULL;
                }
        }
        if (rename(fulloldpath, fullnewpath)) {
                SYSERROR("failed to rename cgroup %s->%s", fulloldpath, fullnewpath);
                free(newname);
                return NULL;
        }

        DEBUG("'%s' renamed to '%s'", oldname, newname);

        return newname;
}

/* create a new cgroup */
struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const char *path_pattern, struct cgroup_meta_data *meta_data, const char *sub_pattern)
{
        char **cgroup_path_components = NULL;
        char **p = NULL;
        char *path_so_far = NULL;
        char **new_cgroup_paths = NULL;
        char **new_cgroup_paths_sub = NULL;
        struct cgroup_mount_point *mp;
        struct cgroup_hierarchy *h;
        struct cgroup_process_info *base_info = NULL;
        struct cgroup_process_info *info_ptr;
        int saved_errno;
        int r;
        unsigned suffix = 0;
        bool had_sub_pattern = false;
        size_t i;

        if (!is_valid_cgroup(name)) {
                ERROR("Invalid cgroup name: '%s'", name);
                errno = EINVAL;
                return NULL;
        }

        if (!strstr(path_pattern, "%n")) {
                ERROR("Invalid cgroup path pattern: '%s'; contains no %%n for specifying container name", path_pattern);
                errno = EINVAL;
                return NULL;
        }

        /* we will modify the result of this operation directly,
         * so we don't have to copy the data structure
         */
        base_info = (path_pattern[0] == '/') ?
                lxc_cgroup_process_info_get_init(meta_data) :
                lxc_cgroup_process_info_get_self(meta_data);
        if (!base_info)
                return NULL;

        new_cgroup_paths = calloc(meta_data->maximum_hierarchy + 1, sizeof(char *));
        if (!new_cgroup_paths)
                goto out_initial_error;

        new_cgroup_paths_sub = calloc(meta_data->maximum_hierarchy + 1, sizeof(char *));
        if (!new_cgroup_paths_sub)
                goto out_initial_error;

        /* find mount points we can use */
        for (info_ptr = base_info; info_ptr; info_ptr = info_ptr->next) {
                h = info_ptr->hierarchy;
                mp = lxc_cgroup_find_mount_point(h, info_ptr->cgroup_path, true);
                if (!mp) {
                        ERROR("Could not find writable mount point for cgroup hierarchy %d while trying to create cgroup.", h->index);
                        goto out_initial_error;
                }
                info_ptr->designated_mount_point = mp;

                if (lxc_string_in_array("ns", (const char **)h->subsystems))
                        continue;
                if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0) {
                        ERROR("Could not set clone_children to 1 for cpuset hierarchy in parent cgroup.");
                        goto out_initial_error;
                }
        }

        /* normalize the path */
        cgroup_path_components = lxc_normalize_path(path_pattern);
        if (!cgroup_path_components)
                goto out_initial_error;

        /* go through the path components to see if we can create them */
        for (p = cgroup_path_components; *p || (sub_pattern && !had_sub_pattern); p++) {
                /* we only want to create the same component with -1, -2, etc.
                 * if the component contains the container name itself, otherwise
                 * it's not an error if it already exists
                 */
                char *p_eff = *p ? *p : (char *)sub_pattern;
                bool contains_name = strstr(p_eff, "%n");
                char *current_component = NULL;
                char *current_subpath = NULL;
                char *current_entire_path = NULL;
                char *parts[3];
                size_t j = 0;
                i = 0;

                /* if we are processing the subpattern, we want to make sure
                 * loop is ended the next time around
                 */
                if (!*p) {
                        had_sub_pattern = true;
                        p--;
                }

                goto find_name_on_this_level;
        
        cleanup_name_on_this_level:
                /* This is reached if we found a name clash.
                 * In that case, remove the cgroup from all previous hierarchies
                 */
                for (j = 0, info_ptr = base_info; j < i && info_ptr; info_ptr = info_ptr->next, j++) {
                        r = remove_cgroup(info_ptr->designated_mount_point, info_ptr->created_paths[info_ptr->created_paths_count - 1], false);
                        if (r < 0)
                                WARN("could not clean up cgroup we created when trying to create container");
                        free(info_ptr->created_paths[info_ptr->created_paths_count - 1]);
                        info_ptr->created_paths[--info_ptr->created_paths_count] = NULL;
                }
                if (current_component != current_subpath)
                        free(current_subpath);
                if (current_component != p_eff)
                        free(current_component);
                current_component = current_subpath = NULL;
                /* try again with another suffix */
                ++suffix;
        
        find_name_on_this_level:
                /* determine name of the path component we should create */
                if (contains_name && suffix > 0) {
                        char *buf = calloc(strlen(name) + 32, 1);
                        if (!buf)
                                goto out_initial_error;
                        snprintf(buf, strlen(name) + 32, "%s-%u", name, suffix);
                        current_component = lxc_string_replace("%n", buf, p_eff);
                        free(buf);
                } else {
                        current_component = contains_name ? lxc_string_replace("%n", name, p_eff) : p_eff;
                }
                parts[0] = path_so_far;
                parts[1] = current_component;
                parts[2] = NULL;
                current_subpath = path_so_far ? lxc_string_join("/", (const char **)parts, false) : current_component;

                /* Now go through each hierarchy and try to create the
                 * corresponding cgroup
                 */
                for (i = 0, info_ptr = base_info; info_ptr; info_ptr = info_ptr->next, i++) {
                        char *parts2[3];

                        if (lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems))
                                continue;
                        current_entire_path = NULL;

                        parts2[0] = !strcmp(info_ptr->cgroup_path, "/") ? "" : info_ptr->cgroup_path;
                        parts2[1] = current_subpath;
                        parts2[2] = NULL;
                        current_entire_path = lxc_string_join("/", (const char **)parts2, false);

                        if (!*p) {
                                /* we are processing the subpath, so only update that one */
                                free(new_cgroup_paths_sub[i]);
                                new_cgroup_paths_sub[i] = strdup(current_entire_path);
                                if (!new_cgroup_paths_sub[i])
                                        goto cleanup_from_error;
                        } else {
                                /* remember which path was used on this controller */
                                free(new_cgroup_paths[i]);
                                new_cgroup_paths[i] = strdup(current_entire_path);
                                if (!new_cgroup_paths[i])
                                        goto cleanup_from_error;
                        }

                        r = create_cgroup(info_ptr->designated_mount_point, current_entire_path);
                        if (r < 0 && errno == EEXIST && contains_name) {
                                /* name clash => try new name with new suffix */
                                free(current_entire_path);
                                current_entire_path = NULL;
                                goto cleanup_name_on_this_level;
                        } else if (r < 0 && errno != EEXIST) {
                                SYSERROR("Could not create cgroup %s", current_entire_path);
                                goto cleanup_from_error;
                        } else if (r == 0) {
                                /* successfully created */
                                r = lxc_grow_array((void ***)&info_ptr->created_paths, &info_ptr->created_paths_capacity, info_ptr->created_paths_count + 1, 8);
                                if (r < 0)
                                        goto cleanup_from_error;
                                info_ptr->created_paths[info_ptr->created_paths_count++] = current_entire_path;
                        } else {
                                /* if we didn't create the cgroup, then we have to make sure that
                                 * further cgroups will be created properly
                                 */
                                if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0) {
                                        ERROR("Could not set clone_children to 1 for cpuset hierarchy in pre-existing cgroup.");
                                        goto cleanup_from_error;
                                }

                                /* already existed but path component of pattern didn't contain '%n',
                                 * so this is not an error; but then we don't need current_entire_path
                                 * anymore...
                                 */
                                free(current_entire_path);
                                current_entire_path = NULL;
                        }
                }

                /* save path so far */
                free(path_so_far);
                path_so_far = strdup(current_subpath);
                if (!path_so_far)
                        goto cleanup_from_error;

                /* cleanup */
                if (current_component != current_subpath)
                        free(current_subpath);
                if (current_component != p_eff)
                        free(current_component);
                current_component = current_subpath = NULL;
                continue;
        
        cleanup_from_error:
                /* called if an error occured in the loop, so we
                 * do some additional cleanup here
                 */
                saved_errno = errno;
                if (current_component != current_subpath)
                        free(current_subpath);
                if (current_component != p_eff)
                        free(current_component);
                free(current_entire_path);
                errno = saved_errno;
                goto out_initial_error;
        }

        /* we're done, now update the paths */
        for (i = 0, info_ptr = base_info; info_ptr; info_ptr = info_ptr->next, i++) {
                /* ignore legacy 'ns' subsystem here, lxc_cgroup_create_legacy
                 * will take care of it
                 * Since we do a continue in above loop, new_cgroup_paths[i] is
                 * unset anyway, as is new_cgroup_paths_sub[i]
                 */
                if (lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems))
                        continue;
                free(info_ptr->cgroup_path);
                info_ptr->cgroup_path = new_cgroup_paths[i];
                info_ptr->cgroup_path_sub = new_cgroup_paths_sub[i];
        }
        /* don't use lxc_free_array since we used the array members
         * to store them in our result...
         */
        free(new_cgroup_paths);
        free(new_cgroup_paths_sub);
        free(path_so_far);
        lxc_free_array((void **)cgroup_path_components, free);
        return base_info;

out_initial_error:
        saved_errno = errno;
        free(path_so_far);
        lxc_cgroup_process_info_free_and_remove(base_info);
        lxc_free_array((void **)new_cgroup_paths, free);
        lxc_free_array((void **)new_cgroup_paths_sub, free);
        lxc_free_array((void **)cgroup_path_components, free);
        errno = saved_errno;
        return NULL;
}

int lxc_cgroup_create_legacy(struct cgroup_process_info *base_info, const char *name, pid_t pid)
{
        struct cgroup_process_info *info_ptr;
        int r;

        for (info_ptr = base_info; info_ptr; info_ptr = info_ptr->next) {
                if (!lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems))
                        continue;
                /*
                 * For any path which has ns cgroup mounted, handler->pid is already
                 * moved into a container called '%d % (handler->pid)'.  Rename it to
                 * the cgroup name and record that.
                 */
                char *tmp = cgroup_rename_nsgroup((const char *)info_ptr->designated_mount_point->mount_point,
                                info_ptr->cgroup_path, pid, name);
                if (!tmp)
                        return -1;
                free(info_ptr->cgroup_path);
                info_ptr->cgroup_path = tmp;
                r = lxc_grow_array((void ***)&info_ptr->created_paths, &info_ptr->created_paths_capacity, info_ptr->created_paths_count + 1, 8);
                if (r < 0)
                        return -1;
                tmp = strdup(tmp);
                if (!tmp)
                        return -1;
                info_ptr->created_paths[info_ptr->created_paths_count++] = tmp;
        }
        return 0;
}

/* get the cgroup membership of a given container */
struct cgroup_process_info *lxc_cgroup_get_container_info(const char *name, const char *lxcpath, struct cgroup_meta_data *meta_data)
{
        struct cgroup_process_info *result = NULL;
        int saved_errno = 0;
        size_t i;
        struct cgroup_process_info **cptr = &result;
        struct cgroup_process_info *entry = NULL;
        char *path = NULL;

        for (i = 0; i <= meta_data->maximum_hierarchy; i++) {
                struct cgroup_hierarchy *h = meta_data->hierarchies[i];
                if (!h || !h->used)
                        continue;

                /* use the command interface to look for the cgroup */
                path = lxc_cmd_get_cgroup_path(name, lxcpath, h->subsystems[0]);
                if (!path)
                        goto out_error;

                entry = calloc(1, sizeof(struct cgroup_process_info));
                if (!entry)
                        goto out_error;
                entry->meta_ref = lxc_cgroup_get_meta(meta_data);
                entry->hierarchy = h;
                entry->cgroup_path = path;
                path = NULL;

                /* it is not an error if we don't find anything here,
                 * it is up to the caller to decide what to do in that
                 * case */
                entry->designated_mount_point = lxc_cgroup_find_mount_point(h, entry->cgroup_path, true);

                *cptr = entry;
                cptr = &entry->next;
                entry = NULL;
        }

        return result;
out_error:
        saved_errno = errno;
        free(path);
        lxc_cgroup_process_info_free(result);
        lxc_cgroup_process_info_free(entry);
        errno = saved_errno;
        return NULL;
}

/* move a processs to the cgroups specified by the membership */
int lxc_cgroupfs_enter(struct cgroup_process_info *info, pid_t pid, bool enter_sub)
{
        char pid_buf[32];
        char *cgroup_tasks_fn;
        int r;
        struct cgroup_process_info *info_ptr;

        snprintf(pid_buf, 32, "%lu", (unsigned long)pid);
        for (info_ptr = info; info_ptr; info_ptr = info_ptr->next) {
                char *cgroup_path = (enter_sub && info_ptr->cgroup_path_sub) ?
                        info_ptr->cgroup_path_sub :
                        info_ptr->cgroup_path;

                if (!info_ptr->designated_mount_point) {
                        info_ptr->designated_mount_point = lxc_cgroup_find_mount_point(info_ptr->hierarchy, cgroup_path, true);
                        if (!info_ptr->designated_mount_point) {
                                SYSERROR("Could not add pid %lu to cgroup %s: internal error (couldn't find any writable mountpoint to cgroup filesystem)", (unsigned long)pid, cgroup_path);
                                return -1;
                        }
                }

                cgroup_tasks_fn = cgroup_to_absolute_path(info_ptr->designated_mount_point, cgroup_path, "/tasks");
                if (!cgroup_tasks_fn) {
                        SYSERROR("Could not add pid %lu to cgroup %s: internal error", (unsigned long)pid, cgroup_path);
                        return -1;
                }

                r = lxc_write_to_file(cgroup_tasks_fn, pid_buf, strlen(pid_buf), false);
                free(cgroup_tasks_fn);
                if (r < 0) {
                        SYSERROR("Could not add pid %lu to cgroup %s: internal error", (unsigned long)pid, cgroup_path);
                        return -1;
                }
        }

        return 0;
}

/* free process membership information */
void lxc_cgroup_process_info_free(struct cgroup_process_info *info)
{
        struct cgroup_process_info *next;
        if (!info)
                return;
        next = info->next;
        lxc_cgroup_put_meta(info->meta_ref);
        free(info->cgroup_path);
        free(info->cgroup_path_sub);
        lxc_free_array((void **)info->created_paths, free);
        free(info);
        lxc_cgroup_process_info_free(next);
}

/* free process membership information and remove cgroups that were created */
void lxc_cgroup_process_info_free_and_remove(struct cgroup_process_info *info)
{
        struct cgroup_process_info *next;
        char **pp;
        if (!info)
                return;
        next = info->next;
        {
                struct cgroup_mount_point *mp = info->designated_mount_point;
                if (!mp)
                        mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, true);
                if (mp)
                        /* ignore return value here, perhaps we created the
                         * '/lxc' cgroup in this container but another container
                         * is still running (for example)
                         */
                        (void)remove_cgroup(mp, info->cgroup_path, true);
        }
        for (pp = info->created_paths; pp && *pp; pp++);
        for ((void)(pp && --pp); info->created_paths && pp >= info->created_paths; --pp) {
                free(*pp);
        }
        free(info->created_paths);
        lxc_cgroup_put_meta(info->meta_ref);
        free(info->cgroup_path);
        free(info->cgroup_path_sub);
        free(info);
        lxc_cgroup_process_info_free_and_remove(next);
}

static char *lxc_cgroup_get_hierarchy_path_handler(const char *subsystem, struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *info = d->info;
        info = find_info_for_subsystem(info, subsystem);
        if (!info)
                return NULL;
        return info->cgroup_path;
}

char *lxc_cgroup_get_hierarchy_path(const char *subsystem, const char *name, const char *lxcpath)
{
        return lxc_cmd_get_cgroup_path(name, lxcpath, subsystem);
}

char *lxc_cgroup_get_hierarchy_abs_path_handler(const char *subsystem, struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *info = d->info;
        struct cgroup_mount_point *mp = NULL;

        info = find_info_for_subsystem(info, subsystem);
        if (!info)
                return NULL;
        if (info->designated_mount_point) {
                mp = info->designated_mount_point;
        } else {
                mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, true);
                if (!mp)
                        return NULL;
        }
        return cgroup_to_absolute_path(mp, info->cgroup_path, NULL);
}

char *lxc_cgroup_get_hierarchy_abs_path(const char *subsystem, const char *name, const char *lxcpath)
{
        struct cgroup_meta_data *meta;
        struct cgroup_process_info *base_info, *info;
        struct cgroup_mount_point *mp;
        char *result = NULL;

        meta = lxc_cgroup_load_meta();
        if (!meta)
                return NULL;
        base_info = lxc_cgroup_get_container_info(name, lxcpath, meta);
        if (!base_info)
                goto out1;
        info = find_info_for_subsystem(base_info, subsystem);
        if (!info)
                goto out2;
        if (info->designated_mount_point) {
                mp = info->designated_mount_point;
        } else {
                mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, true);
                if (!mp)
                        goto out3;
        }
        result = cgroup_to_absolute_path(mp, info->cgroup_path, NULL);
out3:
out2:
        lxc_cgroup_process_info_free(base_info);
out1:
        lxc_cgroup_put_meta(meta);
        return result;
}

int lxc_cgroup_set_handler(const char *filename, const char *value, struct lxc_handler *handler)
{
        char *subsystem = NULL, *p, *path;
        int ret = -1;

        subsystem = alloca(strlen(filename) + 1);
        strcpy(subsystem, filename);
        if ((p = index(subsystem, '.')) != NULL)
                *p = '\0';

        path = lxc_cgroup_get_hierarchy_abs_path_handler(subsystem, handler);
        if (path) {
                ret = do_cgroup_set(path, filename, value);
                free(path);
        }
        return ret;
}

int lxc_cgroup_get_handler(const char *filename, char *value, size_t len, struct lxc_handler *handler)
{
        char *subsystem = NULL, *p, *path;
        int ret = -1;

        subsystem = alloca(strlen(filename) + 1);
        strcpy(subsystem, filename);
        if ((p = index(subsystem, '.')) != NULL)
                *p = '\0';

        path = lxc_cgroup_get_hierarchy_abs_path_handler(subsystem, handler);
        if (path) {
                ret = do_cgroup_get(path, filename, value, len);
                free(path);
        }
        return ret;
}

int lxc_cgroupfs_set(const char *filename, const char *value, const char *name, const char *lxcpath)
{
        char *subsystem = NULL, *p, *path;
        int ret = -1;

        subsystem = alloca(strlen(filename) + 1);
        strcpy(subsystem, filename);
        if ((p = index(subsystem, '.')) != NULL)
                *p = '\0';

        path = lxc_cgroup_get_hierarchy_abs_path(subsystem, name, lxcpath);
        if (path) {
                ret = do_cgroup_set(path, filename, value);
                free(path);
        }
        return ret;
}

int lxc_cgroupfs_get(const char *filename, char *value, size_t len, const char *name, const char *lxcpath)
{
        char *subsystem = NULL, *p, *path;
        int ret = -1;

        subsystem = alloca(strlen(filename) + 1);
        strcpy(subsystem, filename);
        if ((p = index(subsystem, '.')) != NULL)
                *p = '\0';

        path = lxc_cgroup_get_hierarchy_abs_path(subsystem, name, lxcpath);
        if (path) {
                ret = do_cgroup_get(path, filename, value, len);
                free(path);
        }
        return ret;
}

/*
 * lxc_cgroup_path_get: Get the absolute pathname for a cgroup
 * file for a running container.
 *
 * @filename  : the file of interest (e.g. "freezer.state") or
 *              the subsystem name (e.g. "freezer") in which case
 *              the directory where the cgroup may be modified
 *              will be returned
 * @name      : name of container to connect to
 * @lxcpath   : the lxcpath in which the container is running
 *
 * This is the exported function, which determines cgpath from the
 * lxc-start of the @name container running in @lxcpath.
 *
 * Returns path on success, NULL on error. The caller must free()
 * the returned path.
 */
char *lxc_cgroup_path_get(const char *filename, const char *name,
                          const char *lxcpath)
{
        char *subsystem = NULL, *longer_file = NULL, *p, *group, *path;

        subsystem = alloca(strlen(filename) + 1);
        strcpy(subsystem, filename);
        if ((p = index(subsystem, '.')) != NULL) {
                *p = '\0';
                longer_file = alloca(strlen(filename) + 2);
                longer_file[0] = '/';
                strcpy(longer_file + 1, filename);
        }

        group = lxc_cgroup_get_hierarchy_path(subsystem, name, lxcpath);
        if (!group)
                return NULL;

        path = lxc_cgroup_find_abs_path(subsystem, group, true, p ? longer_file : NULL);
        free(group);
        return path;
}

int lxc_setup_mount_cgroup(const char *root, struct lxc_cgroup_info *cgroup_info, int type)
{
        size_t bufsz = strlen(root) + sizeof("/sys/fs/cgroup");
        char *path = NULL;
        char **parts = NULL;
        char *dirname = NULL;
        char *abs_path = NULL;
        char *abs_path2 = NULL;
        struct cgfs_data *cgfs_d;
        struct cgroup_process_info *info, *base_info;
        int r, saved_errno = 0;

        init_cg_ops();

        if (strcmp(active_cg_ops->name, "cgmanager") == 0) {
                // todo - offer to bind-mount /sys/fs/cgroup/cgmanager/
                return 0;
        }

        cgfs_d = cgroup_info->data;
        base_info = cgfs_d->info;

        if (type < LXC_AUTO_CGROUP_RO || type > LXC_AUTO_CGROUP_FULL_MIXED) {
                ERROR("could not mount cgroups into container: invalid type specified internally");
                errno = EINVAL;
                return -1;
        }

        path = calloc(1, bufsz);
        if (!path)
                return -1;
        snprintf(path, bufsz, "%s/sys/fs/cgroup", root);
        r = mount("cgroup_root", path, "tmpfs", MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_RELATIME, "size=10240k,mode=755");
        if (r < 0) {
                SYSERROR("could not mount tmpfs to /sys/fs/cgroup in the container");
                return -1;
        }

        /* now mount all the hierarchies we care about */
        for (info = base_info; info; info = info->next) {
                size_t subsystem_count, i;
                struct cgroup_mount_point *mp = info->designated_mount_point;
                if (!mp)
                        mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, true);
                if (!mp) {
                        SYSERROR("could not find original mount point for cgroup hierarchy while trying to mount cgroup filesystem");
                        goto out_error;
                }

                subsystem_count = lxc_array_len((void **)info->hierarchy->subsystems);
                parts = calloc(subsystem_count + 1, sizeof(char *));
                if (!parts)
                        goto out_error;

                for (i = 0; i < subsystem_count; i++) {
                        if (!strncmp(info->hierarchy->subsystems[i], "name=", 5))
                                parts[i] = info->hierarchy->subsystems[i] + 5;
                        else
                                parts[i] = info->hierarchy->subsystems[i];
                }
                dirname = lxc_string_join(",", (const char **)parts, false);
                if (!dirname)
                        goto out_error;

                /* create subsystem directory */
                abs_path = lxc_append_paths(path, dirname);
                if (!abs_path)
                        goto out_error;
                r = mkdir_p(abs_path, 0755);
                if (r < 0 && errno != EEXIST) {
                        SYSERROR("could not create cgroup subsystem directory /sys/fs/cgroup/%s", dirname);
                        goto out_error;
                }

                abs_path2 = lxc_append_paths(abs_path, info->cgroup_path);
                if (!abs_path2)
                        goto out_error;

                if (type == LXC_AUTO_CGROUP_FULL_RO || type == LXC_AUTO_CGROUP_FULL_RW || type == LXC_AUTO_CGROUP_FULL_MIXED) {
                        /* bind-mount the cgroup entire filesystem there */
                        if (strcmp(mp->mount_prefix, "/") != 0) {
                                /* FIXME: maybe we should just try to remount the entire hierarchy
                                 *        with a regular mount command? may that works? */
                                ERROR("could not automatically mount cgroup-full to /sys/fs/cgroup/%s: host has no mount point for this cgroup filesystem that has access to the root cgroup", dirname);
                                goto out_error;
                        }
                        r = mount(mp->mount_point, abs_path, "none", MS_BIND, 0);
                        if (r < 0) {
                                SYSERROR("error bind-mounting %s to %s", mp->mount_point, abs_path);
                                goto out_error;
                        }
                        /* main cgroup path should be read-only */
                        if (type == LXC_AUTO_CGROUP_FULL_RO || type == LXC_AUTO_CGROUP_FULL_MIXED) {
                                r = mount(NULL, abs_path, NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL);
                                if (r < 0) {
                                        SYSERROR("error re-mounting %s readonly", abs_path);
                                        goto out_error;
                                }
                        }
                        /* own cgroup should be read-write */
                        if (type == LXC_AUTO_CGROUP_FULL_MIXED) {
                                r = mount(abs_path2, abs_path2, NULL, MS_BIND, NULL);
                                if (r < 0) {
                                        SYSERROR("error bind-mounting %s onto itself", abs_path2);
                                        goto out_error;
                                }
                                r = mount(NULL, abs_path2, NULL, MS_REMOUNT|MS_BIND, NULL);
                                if (r < 0) {
                                        SYSERROR("error re-mounting %s readwrite", abs_path2);
                                        goto out_error;
                                }
                        }
                } else {
                        /* create path for container's cgroup */
                        r = mkdir_p(abs_path2, 0755);
                        if (r < 0 && errno != EEXIST) {
                                SYSERROR("could not create cgroup directory /sys/fs/cgroup/%s%s", dirname, info->cgroup_path);
                                goto out_error;
                        }

                        free(abs_path);
                        abs_path = NULL;

                        /* bind-mount container's cgroup to that directory */
                        abs_path = cgroup_to_absolute_path(mp, info->cgroup_path, NULL);
                        if (!abs_path)
                                goto out_error;
                        r = mount(abs_path, abs_path2, "none", MS_BIND, 0);
                        if (r < 0) {
                                SYSERROR("error bind-mounting %s to %s", abs_path, abs_path2);
                                goto out_error;
                        }
                        if (type == LXC_AUTO_CGROUP_RO) {
                                r = mount(NULL, abs_path2, NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL);
                                if (r < 0) {
                                        SYSERROR("error re-mounting %s readonly", abs_path2);
                                        goto out_error;
                                }
                        }
                }

                free(abs_path);
                free(abs_path2);
                abs_path = NULL;
                abs_path2 = NULL;

                /* add symlinks for every single subsystem */
                if (subsystem_count > 1) {
                        for (i = 0; i < subsystem_count; i++) {
                                abs_path = lxc_append_paths(path, parts[i]);
                                if (!abs_path)
                                        goto out_error;
                                r = symlink(dirname, abs_path);
                                if (r < 0)
                                        WARN("could not create symlink %s -> %s in /sys/fs/cgroup of container", parts[i], dirname);
                                free(abs_path);
                                abs_path = NULL;
                        }
                }
                free(dirname);
                free(parts);
                dirname = NULL;
                parts = NULL;
        }

        /* try to remount the tmpfs readonly, since the container shouldn't
         * change anything (this will also make sure that trying to create
         * new cgroups outside the allowed area fails with an error instead
         * of simply causing this to create directories in the tmpfs itself)
         */
        if (type != LXC_AUTO_CGROUP_RW && type != LXC_AUTO_CGROUP_FULL_RW)
                mount(NULL, path, NULL, MS_REMOUNT|MS_RDONLY, NULL);

        free(path);

        return 0;

out_error:
        saved_errno = errno;
        free(path);
        free(dirname);
        free(parts);
        free(abs_path);
        free(abs_path2);
        errno = saved_errno;
        return -1;
}

int lxc_cgroup_nrtasks_handler(struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *info = d->info;
        struct cgroup_mount_point *mp = NULL;
        char *abs_path = NULL;
        int ret;

        if (!info) {
                errno = ENOENT;
                return -1;
        }

        if (info->designated_mount_point) {
                mp = info->designated_mount_point;
        } else {
                mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, false);
                if (!mp)
                        return -1;
        }

        abs_path = cgroup_to_absolute_path(mp, info->cgroup_path, NULL);
        if (!abs_path)
                return -1;

        ret = cgroup_recursive_task_count(abs_path);
        free(abs_path);
        return ret;
}

static struct cgroup_process_info *
lxc_cgroup_process_info_getx(const char *proc_pid_cgroup_str,
                             struct cgroup_meta_data *meta)
{
        struct cgroup_process_info *result = NULL;
        FILE *proc_pid_cgroup = NULL;
        char *line = NULL;
        size_t sz = 0;
        int saved_errno = 0;
        struct cgroup_process_info **cptr = &result;
        struct cgroup_process_info *entry = NULL;

        proc_pid_cgroup = fopen_cloexec(proc_pid_cgroup_str, "r");
        if (!proc_pid_cgroup)
                return NULL;

        while (getline(&line, &sz, proc_pid_cgroup) != -1) {
                /* file format: hierarchy:subsystems:group */
                char *colon1;
                char *colon2;
                char *endptr;
                int hierarchy_number;
                struct cgroup_hierarchy *h = NULL;

                if (!line[0])
                        continue;

                if (line[strlen(line) - 1] == '\n')
                        line[strlen(line) - 1] = '\0';

                colon1 = strchr(line, ':');
                if (!colon1)
                        continue;
                *colon1++ = '\0';
                colon2 = strchr(colon1, ':');
                if (!colon2)
                        continue;
                *colon2++ = '\0';

                endptr = NULL;
                hierarchy_number = strtoul(line, &endptr, 10);
                if (!endptr || *endptr)
                        continue;

                if (hierarchy_number > meta->maximum_hierarchy) {
                        /* we encountered a hierarchy we didn't have before,
                         * so probably somebody remounted some stuff in the
                         * mean time...
                         */
                        errno = EAGAIN;
                        goto out_error;
                }

                h = meta->hierarchies[hierarchy_number];
                if (!h) {
                        /* we encountered a hierarchy that was thought to be
                         * dead before, so probably somebody remounted some
                         * stuff in the mean time...
                         */
                        errno = EAGAIN;
                        goto out_error;
                }

                /* we are told that we should ignore this hierarchy */
                if (!h->used)
                        continue;

                entry = calloc(1, sizeof(struct cgroup_process_info));
                if (!entry)
                        goto out_error;

                entry->meta_ref = lxc_cgroup_get_meta(meta);
                entry->hierarchy = h;
                entry->cgroup_path = strdup(colon2);
                if (!entry->cgroup_path)
                        goto out_error;

                *cptr = entry;
                cptr = &entry->next;
                entry = NULL;
        }

        fclose(proc_pid_cgroup);
        free(line);
        return result;

out_error:
        saved_errno = errno;
        if (proc_pid_cgroup)
                fclose(proc_pid_cgroup);
        lxc_cgroup_process_info_free(result);
        lxc_cgroup_process_info_free(entry);
        free(line);
        errno = saved_errno;
        return NULL;
}

static char **subsystems_from_mount_options(const char *mount_options,
                                            char **kernel_list)
{
        char *token, *str, *saveptr = NULL;
        char **result = NULL;
        size_t result_capacity = 0;
        size_t result_count = 0;
        int saved_errno;
        int r;

        str = alloca(strlen(mount_options)+1);
        strcpy(str, mount_options);
        for (; (token = strtok_r(str, ",", &saveptr)); str = NULL) {
                /* we have a subsystem if it's either in the list of
                 * subsystems provided by the kernel OR if it starts
                 * with name= for named hierarchies
                 */
                if (!strncmp(token, "name=", 5) || lxc_string_in_array(token, (const char **)kernel_list)) {
                        r = lxc_grow_array((void ***)&result, &result_capacity, result_count + 1, 12);
                        if (r < 0)
                                goto out_free;
                        result[result_count + 1] = NULL;
                        result[result_count] = strdup(token);
                        if (!result[result_count])
                                goto out_free;
                        result_count++;
                }
        }

        return result;

out_free:
        saved_errno = errno;
        lxc_free_array((void**)result, free);
        errno = saved_errno;
        return NULL;
}

static void lxc_cgroup_mount_point_free(struct cgroup_mount_point *mp)
{
        if (!mp)
                return;
        free(mp->mount_point);
        free(mp->mount_prefix);
        free(mp);
}

static void lxc_cgroup_hierarchy_free(struct cgroup_hierarchy *h)
{
        if (!h)
                return;
        lxc_free_array((void **)h->subsystems, free);
        free(h->all_mount_points);
        free(h);
}

static bool is_valid_cgroup(const char *name)
{
        const char *p;
        for (p = name; *p; p++) {
                /* Use the ASCII printable characters range(32 - 127)
                 * is reasonable, we kick out 32(SPACE) because it'll
                 * break legacy lxc-ls
                 */
                if (*p <= 32 || *p >= 127 || *p == '/')
                        return false;
        }
        return strcmp(name, ".") != 0 && strcmp(name, "..") != 0;
}

static int create_or_remove_cgroup(bool do_remove,
                struct cgroup_mount_point *mp, const char *path, int recurse)
{
        int r, saved_errno = 0;
        char *buf = cgroup_to_absolute_path(mp, path, NULL);
        if (!buf)
                return -1;

        /* create or remove directory */
        if (do_remove) {
                if (recurse)
                        r = cgroup_rmdir(buf);
                else
                        r = rmdir(buf);
        } else
                r = mkdir(buf, 0777);
        saved_errno = errno;
        free(buf);
        errno = saved_errno;
        return r;
}

static int create_cgroup(struct cgroup_mount_point *mp, const char *path)
{
        return create_or_remove_cgroup(false, mp, path, false);
}

static int remove_cgroup(struct cgroup_mount_point *mp,
                         const char *path, bool recurse)
{
        return create_or_remove_cgroup(true, mp, path, recurse);
}

static char *cgroup_to_absolute_path(struct cgroup_mount_point *mp,
                                     const char *path, const char *suffix)
{
        /* first we have to make sure we subtract the mount point's prefix */
        char *prefix = mp->mount_prefix;
        char *buf;
        ssize_t len, rv;

        /* we want to make sure only absolute paths to cgroups are passed to us */
        if (path[0] != '/') {
                errno = EINVAL;
                return NULL;
        }

        if (prefix && !strcmp(prefix, "/"))
                prefix = NULL;

        /* prefix doesn't match */
        if (prefix && strncmp(prefix, path, strlen(prefix)) != 0) {
                errno = EINVAL;
                return NULL;
        }
        /* if prefix is /foo and path is /foobar */
        if (prefix && path[strlen(prefix)] != '/' && path[strlen(prefix)] != '\0') {
                errno = EINVAL;
                return NULL;
        }

        /* remove prefix from path */
        path += prefix ? strlen(prefix) : 0;

        len = strlen(mp->mount_point) + strlen(path) + (suffix ? strlen(suffix) : 0);
        buf = calloc(len + 1, 1);
        if (!buf)
                return NULL;
        rv = snprintf(buf, len + 1, "%s%s%s", mp->mount_point, path, suffix ? suffix : "");
        if (rv > len) {
                free(buf);
                errno = ENOMEM;
                return NULL;
        }

        return buf;
}

static struct cgroup_process_info *
find_info_for_subsystem(struct cgroup_process_info *info, const char *subsystem)
{
        struct cgroup_process_info *info_ptr;
        for (info_ptr = info; info_ptr; info_ptr = info_ptr->next) {
                struct cgroup_hierarchy *h = info_ptr->hierarchy;
                if (lxc_string_in_array(subsystem, (const char **)h->subsystems))
                        return info_ptr;
        }
        errno = ENOENT;
        return NULL;
}

static int do_cgroup_get(const char *cgroup_path, const char *sub_filename,
                         char *value, size_t len)
{
        const char *parts[3] = {
                cgroup_path,
                sub_filename,
                NULL
        };
        char *filename;
        int ret, saved_errno;

        filename = lxc_string_join("/", parts, false);
        if (!filename)
                return -1;

        ret = lxc_read_from_file(filename, value, len);
        saved_errno = errno;
        free(filename);
        errno = saved_errno;
        return ret;
}

static int do_cgroup_set(const char *cgroup_path, const char *sub_filename,
                         const char *value)
{
        const char *parts[3] = {
                cgroup_path,
                sub_filename,
                NULL
        };
        char *filename;
        int ret, saved_errno;

        filename = lxc_string_join("/", parts, false);
        if (!filename)
                return -1;

        ret = lxc_write_to_file(filename, value, strlen(value), false);
        saved_errno = errno;
        free(filename);
        errno = saved_errno;
        return ret;
}

static int do_setup_cgroup_limits(struct lxc_handler *h,
                           struct lxc_list *cgroup_settings, bool do_devices)
{
        struct lxc_list *iterator;
        struct lxc_cgroup *cg;
        int ret = -1;

        if (lxc_list_empty(cgroup_settings))
                return 0;

        lxc_list_for_each(iterator, cgroup_settings) {
                cg = iterator->elem;

                if (do_devices == !strncmp("devices", cg->subsystem, 7)) {
                        if (strcmp(cg->subsystem, "devices.deny") == 0 &&
                                        cgroup_devices_has_allow_or_deny(h, cg->value, false))
                                continue;
                        if (strcmp(cg->subsystem, "devices.allow") == 0 &&
                                        cgroup_devices_has_allow_or_deny(h, cg->value, true))
                                continue;
                        if (lxc_cgroup_set_handler(cg->subsystem, cg->value, h)) {
                                ERROR("Error setting %s to %s for %s\n",
                                      cg->subsystem, cg->value, h->name);
                                goto out;
                        }
                }

                DEBUG("cgroup '%s' set to '%s'", cg->subsystem, cg->value);
        }

        ret = 0;
        INFO("cgroup has been setup");
out:
        return ret;
}

static bool cgroup_devices_has_allow_or_deny(struct lxc_handler *h,
                                             char *v, bool for_allow)
{
        char *path;
        FILE *devices_list;
        char *line = NULL;
        size_t sz = 0;
        bool ret = !for_allow;
        const char *parts[3] = {
                NULL,
                "devices.list",
                NULL
        };

        // XXX FIXME if users could use something other than 'lxc.devices.deny = a'.
        // not sure they ever do, but they *could*
        // right now, I'm assuming they do NOT
        if (!for_allow && strcmp(v, "a") != 0 && strcmp(v, "a *:* rwm") != 0)
                return false;

        parts[0] = (const char *)lxc_cgroup_get_hierarchy_abs_path_handler("devices", h);
        if (!parts[0])
                return false;
        path = lxc_string_join("/", parts, false);
        if (!path) {
                free((void *)parts[0]);
                return false;
        }

        devices_list = fopen_cloexec(path, "r");
        if (!devices_list) {
                free(path);
                return false;
        }

        while (getline(&line, &sz, devices_list) != -1) {
                size_t len = strlen(line);
                if (len > 0 && line[len-1] == '\n')
                        line[len-1] = '\0';
                if (strcmp(line, "a *:* rwm") == 0) {
                        ret = for_allow;
                        goto out;
                } else if (for_allow && strcmp(line, v) == 0) {
                        ret = true;
                        goto out;
                }
        }

out:
        fclose(devices_list);
        free(line);
        free(path);
        return ret;
}

static int cgroup_recursive_task_count(const char *cgroup_path)
{
        DIR *d;
        struct dirent *dent_buf;
        struct dirent *dent;
        ssize_t name_max;
        int n = 0, r;

        /* see man readdir_r(3) */
        name_max = pathconf(cgroup_path, _PC_NAME_MAX);
        if (name_max <= 0)
                name_max = 255;
        dent_buf = malloc(offsetof(struct dirent, d_name) + name_max + 1);
        if (!dent_buf)
                return -1;

        d = opendir(cgroup_path);
        if (!d) {
                free(dent_buf);
                return 0;
        }

        while (readdir_r(d, dent_buf, &dent) == 0 && dent) {
                const char *parts[3] = {
                        cgroup_path,
                        dent->d_name,
                        NULL
                };
                char *sub_path;
                struct stat st;

                if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, ".."))
                        continue;
                sub_path = lxc_string_join("/", parts, false);
                if (!sub_path) {
                        closedir(d);
                        free(dent_buf);
                        return -1;
                }
                r = stat(sub_path, &st);
                if (r < 0) {
                        closedir(d);
                        free(dent_buf);
                        free(sub_path);
                        return -1;
                }
                if (S_ISDIR(st.st_mode)) {
                        r = cgroup_recursive_task_count(sub_path);
                        if (r >= 0)
                                n += r;
                } else if (!strcmp(dent->d_name, "tasks")) {
                        r = count_lines(sub_path);
                        if (r >= 0)
                                n += r;
                }
                free(sub_path);
        }
        closedir(d);
        free(dent_buf);

        return n;
}

static int count_lines(const char *fn)
{
        FILE *f;
        char *line = NULL;
        size_t sz = 0;
        int n = 0;

        f = fopen_cloexec(fn, "r");
        if (!f)
                return -1;

        while (getline(&line, &sz, f) != -1) {
                n++;
        }
        free(line);
        fclose(f);
        return n;
}

static int handle_cgroup_settings(struct cgroup_mount_point *mp,
                                  char *cgroup_path)
{
        int r, saved_errno = 0;
        char buf[2];

        /* If this is the memory cgroup, we want to enforce hierarchy.
         * But don't fail if for some reason we can't.
         */
        if (lxc_string_in_array("memory", (const char **)mp->hierarchy->subsystems)) {
                char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/memory.use_hierarchy");
                if (cc_path) {
                        r = lxc_read_from_file(cc_path, buf, 1);
                        if (r < 1 || buf[0] != '1') {
                                r = lxc_write_to_file(cc_path, "1", 1, false);
                                if (r < 0)
                                        SYSERROR("failed to set memory.use_hiararchy to 1; continuing");
                        }
                        free(cc_path);
                }
        }

        /* if this is a cpuset hierarchy, we have to set cgroup.clone_children in
         * the base cgroup, otherwise containers will start with an empty cpuset.mems
         * and cpuset.cpus and then
         */
        if (lxc_string_in_array("cpuset", (const char **)mp->hierarchy->subsystems)) {
                char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/cgroup.clone_children");
                if (!cc_path)
                        return -1;
                r = lxc_read_from_file(cc_path, buf, 1);
                if (r == 1 && buf[0] == '1') {
                        free(cc_path);
                        return 0;
                }
                r = lxc_write_to_file(cc_path, "1", 1, false);
                saved_errno = errno;
                free(cc_path);
                errno = saved_errno;
                return r < 0 ? -1 : 0;
        }
        return 0;
}

extern void lxc_monitor_send_state(const char *name, lxc_state_t state,
                            const char *lxcpath);
int do_unfreeze(int freeze, const char *name, const char *lxcpath)
{
        char v[100];
        const char *state = freeze ? "FROZEN" : "THAWED";

        if (lxc_cgroup_set("freezer.state", state, name, lxcpath) < 0) {
                ERROR("Failed to freeze %s:%s", lxcpath, name);
                return -1;
        }
        while (1) {
                if (lxc_cgroup_get("freezer.state", v, 100, name, lxcpath) < 0) {
                        ERROR("Failed to get new freezer state for %s:%s", lxcpath, name);
                        return -1;
                }
                if (v[strlen(v)-1] == '\n')
                        v[strlen(v)-1] = '\0';
                if (strncmp(v, state, strlen(state)) == 0) {
                        if (name)
                                lxc_monitor_send_state(name, freeze ? FROZEN : THAWED, lxcpath);
                        return 0;
                }
                sleep(1);
        }
}

int freeze_unfreeze(const char *name, int freeze, const char *lxcpath)
{
        return do_unfreeze(freeze, name, lxcpath);
}

lxc_state_t freezer_state(const char *name, const char *lxcpath)
{
        char v[100];
        if (lxc_cgroup_get("freezer.state", v, 100, name, lxcpath) < 0)
                return -1;

        if (v[strlen(v)-1] == '\n')
                v[strlen(v)-1] = '\0';
        return lxc_str2state(v);
}

static void cgfs_destroy(struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        if (!d)
                return;
        if (d->info)
                lxc_cgroup_process_info_free_and_remove(d->info);
        if (d->meta)
                lxc_cgroup_put_meta(d->meta);
        free(d);
        handler->cgroup_info->data = NULL;
}

static inline bool cgfs_init(struct lxc_handler *handler)
{
        struct cgfs_data *d = malloc(sizeof(*d));
        if (!d)
                return false;
        d->info = NULL;
        d->meta = lxc_cgroup_load_meta();

        if (!d->meta) {
                ERROR("cgroupfs failed to detect cgroup metadata");
                free(d);
                return false;
        }
        handler->cgroup_info->data = d;
        return true;
}

static inline bool cgfs_create(struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *i;
        struct cgroup_meta_data *md = d->meta;
        i = lxc_cgroupfs_create(handler->name, handler->cgroup_info->cgroup_pattern, md, NULL);
        if (!i)
                return false;
        d->info = i;
        return true;
}

static inline bool cgfs_enter(struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *i = d->info;
        int ret;
        
        ret = lxc_cgroupfs_enter(i, handler->pid, false);

        return ret == 0;
}

static inline bool cgfs_create_legacy(struct lxc_handler *handler)
{
        struct cgfs_data *d = handler->cgroup_info->data;
        struct cgroup_process_info *i = d->info;
        if (lxc_cgroup_create_legacy(i, handler->name, handler->pid) < 0) {
                ERROR("failed to create legacy ns cgroups for '%s'", handler->name);
                return false;
        }
        return true;
}

static char *cgfs_get_cgroup(struct lxc_handler *handler, const char *subsystem)
{
        return lxc_cgroup_get_hierarchy_path_handler(subsystem, handler);
}

static int cgfs_unfreeze_fromhandler(struct lxc_handler *handler)
{
        char *cgabspath, *cgrelpath;
        int ret;

        cgrelpath = lxc_cgroup_get_hierarchy_path_handler("freezer", handler);
        cgabspath = lxc_cgroup_find_abs_path("freezer", cgrelpath, true, NULL);
        if (!cgabspath)
                return -1;

        ret = do_cgroup_set(cgabspath, "freezer.state", "THAWED");
        free(cgabspath);
        return ret;
}

bool cgroupfs_setup_limits(struct lxc_handler *h, bool with_devices)
{
        return do_setup_cgroup_limits(h, &h->conf->cgroup, with_devices) == 0;
}

static struct cgroup_ops cgfs_ops = {
        .destroy = cgfs_destroy,
        .init = cgfs_init,
        .create = cgfs_create,
        .enter = cgfs_enter,
        .create_legacy = cgfs_create_legacy,
        .get_cgroup = cgfs_get_cgroup,
        .get = lxc_cgroupfs_get,
        .set = lxc_cgroupfs_set,
        .unfreeze_fromhandler = cgfs_unfreeze_fromhandler,
        .setup_limits = cgroupfs_setup_limits,
        .name = "cgroupfs",
        .chown = NULL,
};
static void init_cg_ops(void)
{
        if (!use_cgmanager)
                return;
        if (cgmanager_initialized)
                return;
        if (!lxc_init_cgmanager()) {
                ERROR("Could not contact cgroup manager, falling back to cgroupfs");
                active_cg_ops = &cgfs_ops;
        }
}

/*
 * These are the backend-independent cgroup handlers for container
 * start and stop
 */

/* Free all cgroup info held by the handler */
void cgroup_destroy(struct lxc_handler *handler)
{
        if (!handler->cgroup_info)
                return;
        if (active_cg_ops)
                active_cg_ops->destroy(handler);
}

/*
 * Allocate a lxc_cgroup_info for the active cgroup
 * backend, and assign it to the handler
 */
bool cgroup_init(struct lxc_handler *handler)
{
        init_cg_ops();
        handler->cgroup_info = malloc(sizeof(struct lxc_cgroup_info));
        if (!handler->cgroup_info)
                return false;
        memset(handler->cgroup_info, 0, sizeof(struct lxc_cgroup_info));
        /* if we are running as root, use system cgroup pattern, otherwise
         * just create a cgroup under the current one. But also fall back to
         * that if for some reason reading the configuration fails and no
         * default value is available
         */
        if (geteuid() == 0)
                handler->cgroup_info->cgroup_pattern = lxc_global_config_value("lxc.cgroup.pattern");
        if (!handler->cgroup_info->cgroup_pattern)
                handler->cgroup_info->cgroup_pattern = "%n";

        return active_cg_ops->init(handler);
}

/* Create the container cgroups for all requested controllers */
bool cgroup_create(struct lxc_handler *handler)
{
        return active_cg_ops->create(handler);
}

/*
 * Enter the container init into its new cgroups for all
 * requested controllers */
bool cgroup_enter(struct lxc_handler *handler)
{
        return active_cg_ops->enter(handler);
}

bool cgroup_create_legacy(struct lxc_handler *handler)
{
        if (active_cg_ops->create_legacy)
                return active_cg_ops->create_legacy(handler);
        return true;
}

char *cgroup_get_cgroup(struct lxc_handler *handler, const char *subsystem)
{
        return active_cg_ops->get_cgroup(handler, subsystem);
}

int lxc_cgroup_set(const char *filename, const char *value, const char *name, const char *lxcpath)
{
        init_cg_ops();
        return active_cg_ops->set(filename, value, name, lxcpath);
}

int lxc_cgroup_get(const char *filename, char *value, size_t len, const char *name, const char *lxcpath)
{
        init_cg_ops();
        return active_cg_ops->get(filename, value, len, name, lxcpath);
}

int lxc_unfreeze_fromhandler(struct lxc_handler *handler)
{
        return active_cg_ops->unfreeze_fromhandler(handler);
}

bool cgroup_setup_limits(struct lxc_handler *handler, bool with_devices)
{
        return active_cg_ops->setup_limits(handler, with_devices);
}

bool cgroup_chown(struct lxc_handler *handler)
{
        if (active_cg_ops->chown)
                return active_cg_ops->chown(handler);
        return true;
}