+ assert(path);
+
+ r = cg_path_get_slice(path, &slice);
+ if (r < 0)
+ return r;
+
+ start = startswith(slice, "user-");
+ if (!start)
+ return -ENOENT;
+ end = endswith(slice, ".slice");
+ if (!end)
+ return -ENOENT;
+
+ s = strndupa(start, end - start);
+ if (!s)
+ return -ENOENT;
+
+ if (parse_uid(s, &u) < 0)
+ return -EIO;
+
+ if (uid)
+ *uid = u;
+
+ return 0;
+}
+
+int cg_pid_get_owner_uid(pid_t pid, uid_t *uid) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_owner_uid(cgroup, uid);
+}
+
+int cg_path_get_slice(const char *p, char **slice) {
+ const char *e = NULL;
+ size_t m = 0;
+
+ assert(p);
+ assert(slice);
+
+ for (;;) {
+ size_t n;
+
+ p += strspn(p, "/");
+
+ n = strcspn(p, "/");
+ if (n <= 6 || memcmp(p + n - 6, ".slice", 6) != 0) {
+ char *s;
+
+ if (!e)
+ return -ENOENT;
+
+ s = strndup(e, m);
+ if (!s)
+ return -ENOMEM;
+
+ *slice = s;
+ return 0;
+ }
+
+ e = p;
+ m = n;
+
+ p += n;
+ }
+}
+
+int cg_pid_get_slice(pid_t pid, char **slice) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(slice);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_slice(cgroup, slice);
+}
+
+char *cg_escape(const char *p) {
+ bool need_prefix = false;
+
+ /* This implements very minimal escaping for names to be used
+ * as file names in the cgroup tree: any name which might
+ * conflict with a kernel name or is prefixed with '_' is
+ * prefixed with a '_'. That way, when reading cgroup names it
+ * is sufficient to remove a single prefixing underscore if
+ * there is one. */
+
+ /* The return value of this function (unlike cg_unescape())
+ * needs free()! */
+
+ if (p[0] == 0 ||
+ p[0] == '_' ||
+ p[0] == '.' ||
+ streq(p, "notify_on_release") ||
+ streq(p, "release_agent") ||
+ streq(p, "tasks"))
+ need_prefix = true;
+ else {
+ const char *dot;
+
+ dot = strrchr(p, '.');
+ if (dot) {
+
+ if (dot - p == 6 && memcmp(p, "cgroup", 6) == 0)
+ need_prefix = true;
+ else {
+ char *n;
+
+ n = strndupa(p, dot - p);
+
+ if (check_hierarchy(n) >= 0)
+ need_prefix = true;
+ }
+ }
+ }
+
+ if (need_prefix)
+ return strappend("_", p);
+ else
+ return strdup(p);
+}
+
+char *cg_unescape(const char *p) {
+ assert(p);
+
+ /* The return value of this function (unlike cg_escape())
+ * doesn't need free()! */
+
+ if (p[0] == '_')
+ return (char*) p+1;
+
+ return (char*) p;
+}
+
+#define CONTROLLER_VALID \
+ DIGITS LETTERS \
+ "_"