move cgroup-util.[ch] to shared/

1 files changed, 1111 insertions, 0 deletions

diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
new file mode 100644
index 0000000000..904d300952
--- /dev/null
+++ b/src/shared/cgroup-util.c
@@ -0,0 +1,1111 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <ftw.h>
+
+#include "cgroup-util.h"
+#include "log.h"
+#include "set.h"
+#include "macro.h"
+#include "util.h"
+
+int cg_enumerate_processes(const char *controller, const char *path, FILE **_f) {
+        char *fs;
+        int r;
+        FILE *f;
+
+        assert(controller);
+        assert(path);
+        assert(_f);
+
+        if ((r = cg_get_path(controller, path, "cgroup.procs", &fs)) < 0)
+                return r;
+
+        f = fopen(fs, "re");
+        free(fs);
+
+        if (!f)
+                return -errno;
+
+        *_f = f;
+        return 0;
+}
+
+int cg_enumerate_tasks(const char *controller, const char *path, FILE **_f) {
+        char *fs;
+        int r;
+        FILE *f;
+
+        assert(controller);
+        assert(path);
+        assert(_f);
+
+        if ((r = cg_get_path(controller, path, "tasks", &fs)) < 0)
+                return r;
+
+        f = fopen(fs, "re");
+        free(fs);
+
+        if (!f)
+                return -errno;
+
+        *_f = f;
+        return 0;
+}
+
+int cg_read_pid(FILE *f, pid_t *_pid) {
+        unsigned long ul;
+
+        /* Note that the cgroup.procs might contain duplicates! See
+         * cgroups.txt for details. */
+
+        errno = 0;
+        if (fscanf(f, "%lu", &ul) != 1) {
+
+                if (feof(f))
+                        return 0;
+
+                return errno ? -errno : -EIO;
+        }
+
+        if (ul <= 0)
+                return -EIO;
+
+        *_pid = (pid_t) ul;
+        return 1;
+}
+
+int cg_enumerate_subgroups(const char *controller, const char *path, DIR **_d) {
+        char *fs;
+        int r;
+        DIR *d;
+
+        assert(controller);
+        assert(path);
+        assert(_d);
+
+        /* This is not recursive! */
+
+        if ((r = cg_get_path(controller, path, NULL, &fs)) < 0)
+                return r;
+
+        d = opendir(fs);
+        free(fs);
+
+        if (!d)
+                return -errno;
+
+        *_d = d;
+        return 0;
+}
+
+int cg_read_subgroup(DIR *d, char **fn) {
+        struct dirent *de;
+
+        assert(d);
+
+        errno = 0;
+        while ((de = readdir(d))) {
+                char *b;
+
+                if (de->d_type != DT_DIR)
+                        continue;
+
+                if (streq(de->d_name, ".") ||
+                    streq(de->d_name, ".."))
+                        continue;
+
+                if (!(b = strdup(de->d_name)))
+                        return -ENOMEM;
+
+                *fn = b;
+                return 1;
+        }
+
+        if (errno)
+                return -errno;
+
+        return 0;
+}
+
+int cg_rmdir(const char *controller, const char *path, bool honour_sticky) {
+        char *p;
+        int r;
+
+        r = cg_get_path(controller, path, NULL, &p);
+        if (r < 0)
+                return r;
+
+        if (honour_sticky) {
+                char *tasks;
+
+                /* If the sticky bit is set don't remove the directory */
+
+                tasks = strappend(p, "/tasks");
+                if (!tasks) {
+                        free(p);
+                        return -ENOMEM;
+                }
+
+                r = file_is_priv_sticky(tasks);
+                free(tasks);
+
+                if (r > 0) {
+                        free(p);
+                        return 0;
+                }
+        }
+
+        r = rmdir(p);
+        free(p);
+
+        return (r < 0 && errno != ENOENT) ? -errno : 0;
+}
+
+int cg_kill(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, Set *s) {
+        bool done = false;
+        int r, ret = 0;
+        pid_t my_pid;
+        FILE *f = NULL;
+        Set *allocated_set = NULL;
+
+        assert(controller);
+        assert(path);
+        assert(sig >= 0);
+
+        /* This goes through the tasks list and kills them all. This
+         * is repeated until no further processes are added to the
+         * tasks list, to properly handle forking processes */
+
+        if (!s)
+                if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
+                        return -ENOMEM;
+
+        my_pid = getpid();
+
+        do {
+                pid_t pid = 0;
+                done = true;
+
+                if ((r = cg_enumerate_processes(controller, path, &f)) < 0) {
+                        if (ret >= 0 && r != -ENOENT)
+                                ret = r;
+
+                        goto finish;
+                }
+
+                while ((r = cg_read_pid(f, &pid)) > 0) {
+
+                        if (pid == my_pid && ignore_self)
+                                continue;
+
+                        if (set_get(s, LONG_TO_PTR(pid)) == LONG_TO_PTR(pid))
+                                continue;
+
+                        /* If we haven't killed this process yet, kill
+                         * it */
+                        if (kill(pid, sig) < 0) {
+                                if (ret >= 0 && errno != ESRCH)
+                                        ret = -errno;
+                        } else if (ret == 0) {
+
+                                if (sigcont)
+                                        kill(pid, SIGCONT);
+
+                                ret = 1;
+                        }
+
+                        done = false;
+
+                        if ((r = set_put(s, LONG_TO_PTR(pid))) < 0) {
+                                if (ret >= 0)
+                                        ret = r;
+
+                                goto finish;
+                        }
+                }
+
+                if (r < 0) {
+                        if (ret >= 0)
+                                ret = r;
+
+                        goto finish;
+                }
+
+                fclose(f);
+                f = NULL;
+
+                /* To avoid racing against processes which fork
+                 * quicker than we can kill them we repeat this until
+                 * no new pids need to be killed. */
+
+        } while (!done);
+
+finish:
+        if (allocated_set)
+                set_free(allocated_set);
+
+        if (f)
+                fclose(f);
+
+        return ret;
+}
+
+int cg_kill_recursive(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, bool rem, Set *s) {
+        int r, ret = 0;
+        DIR *d = NULL;
+        char *fn;
+        Set *allocated_set = NULL;
+
+        assert(path);
+        assert(controller);
+        assert(sig >= 0);
+
+        if (!s)
+                if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
+                        return -ENOMEM;
+
+        ret = cg_kill(controller, path, sig, sigcont, ignore_self, s);
+
+        if ((r = cg_enumerate_subgroups(controller, path, &d)) < 0) {
+                if (ret >= 0 && r != -ENOENT)
+                        ret = r;
+
+                goto finish;
+        }
+
+        while ((r = cg_read_subgroup(d, &fn)) > 0) {
+                char *p = NULL;
+
+                r = asprintf(&p, "%s/%s", path, fn);
+                free(fn);
+
+                if (r < 0) {
+                        if (ret >= 0)
+                                ret = -ENOMEM;
+
+                        goto finish;
+                }
+
+                r = cg_kill_recursive(controller, p, sig, sigcont, ignore_self, rem, s);
+                free(p);
+
+                if (r != 0 && ret >= 0)
+                        ret = r;
+        }
+
+        if (r < 0 && ret >= 0)
+                ret = r;
+
+        if (rem)
+                if ((r = cg_rmdir(controller, path, true)) < 0) {
+                        if (ret >= 0 &&
+                            r != -ENOENT &&
+                            r != -EBUSY)
+                                ret = r;
+                }
+
+finish:
+        if (d)
+                closedir(d);
+
+        if (allocated_set)
+                set_free(allocated_set);
+
+        return ret;
+}
+
+int cg_kill_recursive_and_wait(const char *controller, const char *path, bool rem) {
+        unsigned i;
+
+        assert(path);
+        assert(controller);
+
+        /* This safely kills all processes; first it sends a SIGTERM,
+         * then checks 8 times after 200ms whether the group is now
+         * empty, then kills everything that is left with SIGKILL and
+         * finally checks 5 times after 200ms each whether the group
+         * is finally empty. */
+
+        for (i = 0; i < 15; i++) {
+                int sig, r;
+
+                if (i <= 0)
+                        sig = SIGTERM;
+                else if (i == 9)
+                        sig = SIGKILL;
+                else
+                        sig = 0;
+
+                if ((r = cg_kill_recursive(controller, path, sig, true, true, rem, NULL)) <= 0)
+                        return r;
+
+                usleep(200 * USEC_PER_MSEC);
+        }
+
+        return 0;
+}
+
+int cg_migrate(const char *controller, const char *from, const char *to, bool ignore_self) {
+        bool done = false;
+        Set *s;
+        int r, ret = 0;
+        pid_t my_pid;
+        FILE *f = NULL;
+
+        assert(controller);
+        assert(from);
+        assert(to);
+
+        if (!(s = set_new(trivial_hash_func, trivial_compare_func)))
+                return -ENOMEM;
+
+        my_pid = getpid();
+
+        do {
+                pid_t pid = 0;
+                done = true;
+
+                if ((r = cg_enumerate_tasks(controller, from, &f)) < 0) {
+                        if (ret >= 0 && r != -ENOENT)
+                                ret = r;
+
+                        goto finish;
+                }
+
+                while ((r = cg_read_pid(f, &pid)) > 0) {
+
+                        /* This might do weird stuff if we aren't a
+                         * single-threaded program. However, we
+                         * luckily know we are not */
+                        if (pid == my_pid && ignore_self)
+                                continue;
+
+                        if (set_get(s, LONG_TO_PTR(pid)) == LONG_TO_PTR(pid))
+                                continue;
+
+                        if ((r = cg_attach(controller, to, pid)) < 0) {
+                                if (ret >= 0 && r != -ESRCH)
+                                        ret = r;
+                        } else if (ret == 0)
+                                ret = 1;
+
+                        done = false;
+
+                        if ((r = set_put(s, LONG_TO_PTR(pid))) < 0) {
+                                if (ret >= 0)
+                                        ret = r;
+
+                                goto finish;
+                        }
+                }
+
+                if (r < 0) {
+                        if (ret >= 0)
+                                ret = r;
+
+                        goto finish;
+                }
+
+                fclose(f);
+                f = NULL;
+
+        } while (!done);
+
+finish:
+        set_free(s);
+
+        if (f)
+                fclose(f);
+
+        return ret;
+}
+
+int cg_migrate_recursive(const char *controller, const char *from, const char *to, bool ignore_self, bool rem) {
+        int r, ret = 0;
+        DIR *d = NULL;
+        char *fn;
+
+        assert(controller);
+        assert(from);
+        assert(to);
+
+        ret = cg_migrate(controller, from, to, ignore_self);
+
+        if ((r = cg_enumerate_subgroups(controller, from, &d)) < 0) {
+                if (ret >= 0 && r != -ENOENT)
+                        ret = r;
+                goto finish;
+        }
+
+        while ((r = cg_read_subgroup(d, &fn)) > 0) {
+                char *p = NULL;
+
+                r = asprintf(&p, "%s/%s", from, fn);
+                free(fn);
+
+                if (r < 0) {
+                        if (ret >= 0)
+                                ret = -ENOMEM;
+
+                        goto finish;
+                }
+
+                r = cg_migrate_recursive(controller, p, to, ignore_self, rem);
+                free(p);
+
+                if (r != 0 && ret >= 0)
+                        ret = r;
+        }
+
+        if (r < 0 && ret >= 0)
+                ret = r;
+
+        if (rem)
+                if ((r = cg_rmdir(controller, from, true)) < 0) {
+                        if (ret >= 0 &&
+                            r != -ENOENT &&
+                            r != -EBUSY)
+                                ret = r;
+                }
+
+finish:
+        if (d)
+                closedir(d);
+
+        return ret;
+}
+
+int cg_get_path(const char *controller, const char *path, const char *suffix, char **fs) {
+        const char *p;
+        char *t;
+        static __thread bool good = false;
+
+        assert(controller);
+        assert(fs);
+
+        if (_unlikely_(!good)) {
+                int r;
+
+                r = path_is_mount_point("/sys/fs/cgroup", false);
+                if (r <= 0)
+                        return r < 0 ? r : -ENOENT;
+
+                /* Cache this to save a few stat()s */
+                good = true;
+        }
+
+        if (isempty(controller))
+                return -EINVAL;
+
+        /* This is a very minimal lookup from controller names to
+         * paths. Since we have mounted most hierarchies ourselves
+         * should be kinda safe, but eventually we might want to
+         * extend this to have a fallback to actually check
+         * /proc/mounts. Might need caching then. */
+
+        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER))
+                p = "systemd";
+        else if (startswith(controller, "name="))
+                p = controller + 5;
+        else
+                p = controller;
+
+        if (path && suffix)
+                t = join("/sys/fs/cgroup/", p, "/", path, "/", suffix, NULL);
+        else if (path)
+                t = join("/sys/fs/cgroup/", p, "/", path, NULL);
+        else if (suffix)
+                t = join("/sys/fs/cgroup/", p, "/", suffix, NULL);
+        else
+                t = join("/sys/fs/cgroup/", p, NULL);
+
+        if (!t)
+                return -ENOMEM;
+
+        path_kill_slashes(t);
+
+        *fs = t;
+        return 0;
+}
+
+static int trim_cb(const char *path, const struct stat *sb, int typeflag, struct FTW *ftwbuf) {
+        char *p;
+        bool is_sticky;
+
+        if (typeflag != FTW_DP)
+                return 0;
+
+        if (ftwbuf->level < 1)
+                return 0;
+
+        p = strappend(path, "/tasks");
+        if (!p) {
+                errno = ENOMEM;
+                return 1;
+        }
+
+        is_sticky = file_is_priv_sticky(p) > 0;
+        free(p);
+
+        if (is_sticky)
+                return 0;
+
+        rmdir(path);
+        return 0;
+}
+
+int cg_trim(const char *controller, const char *path, bool delete_root) {
+        char *fs;
+        int r = 0;
+
+        assert(controller);
+        assert(path);
+
+        r = cg_get_path(controller, path, NULL, &fs);
+        if (r < 0)
+                return r;
+
+        errno = 0;
+        if (nftw(fs, trim_cb, 64, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) < 0)
+                r = errno ? -errno : -EIO;
+
+        if (delete_root) {
+                bool is_sticky;
+                char *p;
+
+                p = strappend(fs, "/tasks");
+                if (!p) {
+                        free(fs);
+                        return -ENOMEM;
+                }
+
+                is_sticky = file_is_priv_sticky(p) > 0;
+                free(p);
+
+                if (!is_sticky)
+                        if (rmdir(fs) < 0 && errno != ENOENT) {
+                                if (r == 0)
+                                        r = -errno;
+                        }
+        }
+
+        free(fs);
+
+        return r;
+}
+
+int cg_delete(const char *controller, const char *path) {
+        char *parent;
+        int r;
+
+        assert(controller);
+        assert(path);
+
+        if ((r = parent_of_path(path, &parent)) < 0)
+                return r;
+
+        r = cg_migrate_recursive(controller, path, parent, false, true);
+        free(parent);
+
+        return r == -ENOENT ? 0 : r;
+}
+
+int cg_create(const char *controller, const char *path) {
+        char *fs;
+        int r;
+
+        assert(controller);
+        assert(path);
+
+        if ((r = cg_get_path(controller, path, NULL, &fs)) < 0)
+                return r;
+
+        r = mkdir_parents(fs, 0755);
+
+        if (r >= 0) {
+                if (mkdir(fs, 0755) >= 0)
+                        r = 1;
+                else if (errno == EEXIST)
+                        r = 0;
+                else
+                        r = -errno;
+        }
+
+        free(fs);
+
+        return r;
+}
+
+int cg_attach(const char *controller, const char *path, pid_t pid) {
+        char *fs;
+        int r;
+        char c[32];
+
+        assert(controller);
+        assert(path);
+        assert(pid >= 0);
+
+        if ((r = cg_get_path(controller, path, "tasks", &fs)) < 0)
+                return r;
+
+        if (pid == 0)
+                pid = getpid();
+
+        snprintf(c, sizeof(c), "%lu\n", (unsigned long) pid);
+        char_array_0(c);
+
+        r = write_one_line_file(fs, c);
+        free(fs);
+
+        return r;
+}
+
+int cg_create_and_attach(const char *controller, const char *path, pid_t pid) {
+        int r, q;
+
+        assert(controller);
+        assert(path);
+        assert(pid >= 0);
+
+        if ((r = cg_create(controller, path)) < 0)
+                return r;
+
+        if ((q = cg_attach(controller, path, pid)) < 0)
+                return q;
+
+        /* This does not remove the cgroup on failure */
+
+        return r;
+}
+
+int cg_set_group_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid) {
+        char *fs;
+        int r;
+
+        assert(controller);
+        assert(path);
+
+        if (mode != (mode_t) -1)
+                mode &= 0777;
+
+        r = cg_get_path(controller, path, NULL, &fs);
+        if (r < 0)
+                return r;
+
+        r = chmod_and_chown(fs, mode, uid, gid);
+        free(fs);
+
+        return r;
+}
+
+int cg_set_task_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid, int sticky) {
+        char *fs;
+        int r;
+
+        assert(controller);
+        assert(path);
+
+        if (mode == (mode_t) -1 && uid == (uid_t) -1 && gid == (gid_t) -1 && sticky < 0)
+                return 0;
+
+        if (mode != (mode_t) -1)
+                mode &= 0666;
+
+        r = cg_get_path(controller, path, "tasks", &fs);
+        if (r < 0)
+                return r;
+
+        if (sticky >= 0 && mode != (mode_t) -1)
+                /* Both mode and sticky param are passed */
+                mode |= (sticky ? S_ISVTX : 0);
+        else if ((sticky >= 0 && mode == (mode_t) -1) ||
+                 (mode != (mode_t) -1 && sticky < 0)) {
+                struct stat st;
+
+                /* Only one param is passed, hence read the current
+                 * mode from the file itself */
+
+                r = lstat(fs, &st);
+                if (r < 0) {
+                        free(fs);
+                        return -errno;
+                }
+
+                if (mode == (mode_t) -1)
+                        /* No mode set, we just shall set the sticky bit */
+                        mode = (st.st_mode & ~S_ISVTX) | (sticky ? S_ISVTX : 0);
+                else
+                        /* Only mode set, leave sticky bit untouched */
+                        mode = (st.st_mode & ~0777) | mode;
+        }
+
+        r = chmod_and_chown(fs, mode, uid, gid);
+        free(fs);
+
+        return r;
+}
+
+int cg_get_by_pid(const char *controller, pid_t pid, char **path) {
+        int r;
+        char *p = NULL;
+        FILE *f;
+        char *fs;
+        size_t cs;
+
+        assert(controller);
+        assert(path);
+        assert(pid >= 0);
+
+        if (pid == 0)
+                pid = getpid();
+
+        if (asprintf(&fs, "/proc/%lu/cgroup", (unsigned long) pid) < 0)
+                return -ENOMEM;
+
+        f = fopen(fs, "re");
+        free(fs);
+
+        if (!f)
+                return errno == ENOENT ? -ESRCH : -errno;
+
+        cs = strlen(controller);
+
+        while (!feof(f)) {
+                char line[LINE_MAX];
+                char *l;
+
+                errno = 0;
+                if (!(fgets(line, sizeof(line), f))) {
+                        if (feof(f))
+                                break;
+
+                        r = errno ? -errno : -EIO;
+                        goto finish;
+                }
+
+                truncate_nl(line);
+
+                if (!(l = strchr(line, ':')))
+                        continue;
+
+                l++;
+                if (strncmp(l, controller, cs) != 0)
+                        continue;
+
+                if (l[cs] != ':')
+                        continue;
+
+                if (!(p = strdup(l + cs + 1))) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                *path = p;
+                r = 0;
+                goto finish;
+        }
+
+        r = -ENOENT;
+
+finish:
+        fclose(f);
+
+        return r;
+}
+
+int cg_install_release_agent(const char *controller, const char *agent) {
+        char *fs = NULL, *contents = NULL, *line = NULL, *sc;
+        int r;
+
+        assert(controller);
+        assert(agent);
+
+        if ((r = cg_get_path(controller, NULL, "release_agent", &fs)) < 0)
+                return r;
+
+        if ((r = read_one_line_file(fs, &contents)) < 0)
+                goto finish;
+
+        sc = strstrip(contents);
+        if (sc[0] == 0) {
+
+                if (asprintf(&line, "%s\n", agent) < 0) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                if ((r = write_one_line_file(fs, line)) < 0)
+                        goto finish;
+
+        } else if (!streq(sc, agent)) {
+                r = -EEXIST;
+                goto finish;
+        }
+
+        free(fs);
+        fs = NULL;
+        if ((r = cg_get_path(controller, NULL, "notify_on_release", &fs)) < 0)
+                goto finish;
+
+        free(contents);
+        contents = NULL;
+        if ((r = read_one_line_file(fs, &contents)) < 0)
+                goto finish;
+
+        sc = strstrip(contents);
+
+        if (streq(sc, "0")) {
+                if ((r = write_one_line_file(fs, "1\n")) < 0)
+                        goto finish;
+
+                r = 1;
+        } else if (!streq(sc, "1")) {
+                r = -EIO;
+                goto finish;
+        } else
+                r = 0;
+
+finish:
+        free(fs);
+        free(contents);
+        free(line);
+
+        return r;
+}
+
+int cg_is_empty(const char *controller, const char *path, bool ignore_self) {
+        pid_t pid = 0;
+        int r;
+        FILE *f = NULL;
+        bool found = false;
+
+        assert(controller);
+        assert(path);
+
+        if ((r = cg_enumerate_tasks(controller, path, &f)) < 0)
+                return r == -ENOENT ? 1 : r;
+
+        while ((r = cg_read_pid(f, &pid)) > 0) {
+
+                if (ignore_self && pid == getpid())
+                        continue;
+
+                found = true;
+                break;
+        }
+
+        fclose(f);
+
+        if (r < 0)
+                return r;
+
+        return !found;
+}
+
+int cg_is_empty_recursive(const char *controller, const char *path, bool ignore_self) {
+        int r;
+        DIR *d = NULL;
+        char *fn;
+
+        assert(controller);
+        assert(path);
+
+        if ((r = cg_is_empty(controller, path, ignore_self)) <= 0)
+                return r;
+
+        if ((r = cg_enumerate_subgroups(controller, path, &d)) < 0)
+                return r == -ENOENT ? 1 : r;
+
+        while ((r = cg_read_subgroup(d, &fn)) > 0) {
+                char *p = NULL;
+
+                r = asprintf(&p, "%s/%s", path, fn);
+                free(fn);
+
+                if (r < 0) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                r = cg_is_empty_recursive(controller, p, ignore_self);
+                free(p);
+
+                if (r <= 0)
+                        goto finish;
+        }
+
+        if (r >= 0)
+                r = 1;
+
+finish:
+
+        if (d)
+                closedir(d);
+
+        return r;
+}
+
+int cg_split_spec(const char *spec, char **controller, char **path) {
+        const char *e;
+        char *t = NULL, *u = NULL;
+
+        assert(spec);
+        assert(controller || path);
+
+        if (*spec == '/') {
+
+                if (path) {
+                        if (!(t = strdup(spec)))
+                                return -ENOMEM;
+
+                        *path = t;
+                }
+
+                if (controller)
+                        *controller = NULL;
+
+                return 0;
+        }
+
+        if (!(e = strchr(spec, ':'))) {
+
+                if (strchr(spec, '/') || spec[0] == 0)
+                        return -EINVAL;
+
+                if (controller) {
+                        if (!(t = strdup(spec)))
+                                return -ENOMEM;
+
+                        *controller = t;
+                }
+
+                if (path)
+                        *path = NULL;
+
+                return 0;
+        }
+
+        if (e[1] != '/' ||
+            e == spec ||
+            memchr(spec, '/', e-spec))
+                return -EINVAL;
+
+        if (controller)
+                if (!(t = strndup(spec, e-spec)))
+                        return -ENOMEM;
+
+        if (path)
+                if (!(u = strdup(e+1))) {
+                        free(t);
+                        return -ENOMEM;
+                }
+
+        if (controller)
+                *controller = t;
+
+        if (path)
+                *path = u;
+
+        return 0;
+}
+
+int cg_join_spec(const char *controller, const char *path, char **spec) {
+        assert(controller);
+        assert(path);
+
+        if (!path_is_absolute(path) ||
+            controller[0] == 0 ||
+            strchr(controller, ':') ||
+            strchr(controller, '/'))
+                return -EINVAL;
+
+        if (asprintf(spec, "%s:%s", controller, path) < 0)
+                return -ENOMEM;
+
+        return 0;
+}
+
+int cg_fix_path(const char *path, char **result) {
+        char *t, *c, *p;
+        int r;
+
+        assert(path);
+        assert(result);
+
+        /* First check if it already is a filesystem path */
+        if (path_is_absolute(path) &&
+            path_startswith(path, "/sys/fs/cgroup") &&
+            access(path, F_OK) >= 0) {
+
+                if (!(t = strdup(path)))
+                        return -ENOMEM;
+
+                *result = t;
+                return 0;
+        }
+
+        /* Otherwise treat it as cg spec */
+        if ((r = cg_split_spec(path, &c, &p)) < 0)
+                return r;
+
+        r = cg_get_path(c ? c : SYSTEMD_CGROUP_CONTROLLER, p ? p : "/", NULL, result);
+        free(c);
+        free(p);
+
+        return r;
+}
+
+int cg_get_user_path(char **path) {
+        char *root, *p;
+
+        assert(path);
+
+        /* Figure out the place to put user cgroups below. We use the
+         * same as PID 1 has but with the "/system" suffix replaced by
+         * "/user" */
+
+        if (cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 1, &root) < 0)
+                p = strdup("/user");
+        else {
+                if (endswith(root, "/system"))
+                        root[strlen(root) - 7] = 0;
+                else if (streq(root, "/"))
+                        root[0] = 0;
+
+                p = strappend(root, "/user");
+                free(root);
+        }
+
+        if (!p)
+                return -ENOMEM;
+
+        *path = p;
+        return 0;
+}