+int cg_path_decode_unit(const char *cgroup, char **unit){
+ char *c, *s;
+ size_t n;
+
+ assert(cgroup);
+ assert(unit);
+
+ n = strcspn(cgroup, "/");
+ if (n < 3)
+ return -ENXIO;
+
+ c = strndupa(cgroup, n);
+ c = cg_unescape(c);
+
+ if (!unit_name_is_valid(c, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE))
+ return -ENXIO;
+
+ s = strdup(c);
+ if (!s)
+ return -ENOMEM;
+
+ *unit = s;
+ return 0;
+}
+
+static bool valid_slice_name(const char *p, size_t n) {
+
+ if (!p)
+ return false;
+
+ if (n < strlen("x.slice"))
+ return false;
+
+ if (memcmp(p + n - 6, ".slice", 6) == 0) {
+ char buf[n+1], *c;
+
+ memcpy(buf, p, n);
+ buf[n] = 0;
+
+ c = cg_unescape(buf);
+
+ return unit_name_is_valid(c, UNIT_NAME_PLAIN);
+ }
+
+ return false;
+}
+
+static const char *skip_slices(const char *p) {
+ assert(p);
+
+ /* Skips over all slice assignments */
+
+ for (;;) {
+ size_t n;
+
+ p += strspn(p, "/");
+
+ n = strcspn(p, "/");
+ if (!valid_slice_name(p, n))
+ return p;
+
+ p += n;
+ }
+}
+
+int cg_path_get_unit(const char *path, char **ret) {
+ const char *e;
+ char *unit;
+ int r;
+
+ assert(path);
+ assert(ret);
+
+ e = skip_slices(path);
+
+ r = cg_path_decode_unit(e, &unit);
+ if (r < 0)
+ return r;
+
+ /* We skipped over the slices, don't accept any now */
+ if (endswith(unit, ".slice")) {
+ free(unit);
+ return -ENXIO;
+ }
+
+ *ret = unit;
+ return 0;
+}
+
+int cg_pid_get_unit(pid_t pid, char **unit) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(unit);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_unit(cgroup, unit);
+}
+
+/**
+ * Skip session-*.scope, but require it to be there.
+ */
+static const char *skip_session(const char *p) {
+ size_t n;
+
+ if (isempty(p))
+ return NULL;
+
+ p += strspn(p, "/");
+
+ n = strcspn(p, "/");
+ if (n < strlen("session-x.scope"))
+ return NULL;
+
+ if (memcmp(p, "session-", 8) == 0 && memcmp(p + n - 6, ".scope", 6) == 0) {
+ char buf[n - 8 - 6 + 1];
+
+ memcpy(buf, p + 8, n - 8 - 6);
+ buf[n - 8 - 6] = 0;
+
+ /* Note that session scopes never need unescaping,
+ * since they cannot conflict with the kernel's own
+ * names, hence we don't need to call cg_unescape()
+ * here. */
+
+ if (!session_id_valid(buf))
+ return false;
+
+ p += n;
+ p += strspn(p, "/");
+ return p;
+ }
+
+ return NULL;
+}
+
+/**
+ * Skip user@*.service, but require it to be there.
+ */
+static const char *skip_user_manager(const char *p) {
+ size_t n;
+
+ if (isempty(p))
+ return NULL;
+
+ p += strspn(p, "/");
+
+ n = strcspn(p, "/");
+ if (n < strlen("user@x.service"))
+ return NULL;
+
+ if (memcmp(p, "user@", 5) == 0 && memcmp(p + n - 8, ".service", 8) == 0) {
+ char buf[n - 5 - 8 + 1];
+
+ memcpy(buf, p + 5, n - 5 - 8);
+ buf[n - 5 - 8] = 0;
+
+ /* Note that user manager services never need unescaping,
+ * since they cannot conflict with the kernel's own
+ * names, hence we don't need to call cg_unescape()
+ * here. */
+
+ if (parse_uid(buf, NULL) < 0)
+ return NULL;
+
+ p += n;
+ p += strspn(p, "/");
+
+ return p;
+ }
+
+ return NULL;
+}
+
+static const char *skip_user_prefix(const char *path) {
+ const char *e, *t;
+
+ assert(path);
+
+ /* Skip slices, if there are any */
+ e = skip_slices(path);
+
+ /* Skip the user manager, if it's in the path now... */
+ t = skip_user_manager(e);
+ if (t)
+ return t;
+
+ /* Alternatively skip the user session if it is in the path... */
+ return skip_session(e);
+}
+
+int cg_path_get_user_unit(const char *path, char **ret) {
+ const char *t;
+
+ assert(path);
+ assert(ret);
+
+ t = skip_user_prefix(path);
+ if (!t)
+ return -ENXIO;
+
+ /* And from here on it looks pretty much the same as for a
+ * system unit, hence let's use the same parser from here
+ * on. */
+ return cg_path_get_unit(t, ret);
+}
+
+int cg_pid_get_user_unit(pid_t pid, char **unit) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(unit);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_user_unit(cgroup, unit);
+}
+
+int cg_path_get_machine_name(const char *path, char **machine) {
+ _cleanup_free_ char *u = NULL, *sl = NULL;
+ int r;
+
+ r = cg_path_get_unit(path, &u);
+ if (r < 0)
+ return r;
+
+ sl = strjoin("/run/systemd/machines/unit:", u, NULL);
+ if (!sl)
+ return -ENOMEM;
+
+ return readlink_malloc(sl, machine);
+}