build-sys: fix built with --disable-logind

src/shared/cgroup-util.c

@@ -1149,3 +1149,108 @@ char **cg_shorten_controllers(char **controllers) {
         *t = NULL;
         return controllers;
 }
+
+int cg_pid_get_cgroup(pid_t pid, char **root, char **cgroup) {
+        char *cg_process, *cg_init, *p;
+        int r;
+
+        assert(pid >= 0);
+
+        if (pid == 0)
+                pid = getpid();
+
+        r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, pid, &cg_process);
+        if (r < 0)
+                return r;
+
+        r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 1, &cg_init);
+        if (r < 0) {
+                free(cg_process);
+                return r;
+        }
+
+        if (endswith(cg_init, "/system"))
+                cg_init[strlen(cg_init)-7] = 0;
+        else if (streq(cg_init, "/"))
+                cg_init[0] = 0;
+
+        if (startswith(cg_process, cg_init))
+                p = cg_process + strlen(cg_init);
+        else
+                p = cg_process;
+
+        free(cg_init);
+
+        if (cgroup) {
+                char* c;
+
+                c = strdup(p);
+                if (!c) {
+                        free(cg_process);
+                        return -ENOMEM;
+                }
+
+                *cgroup = c;
+        }
+
+        if (root) {
+                cg_process[p-cg_process] = 0;
+                *root = cg_process;
+        } else
+                free(cg_process);
+
+        return 0;
+}
+
+int cg_pid_get_unit(pid_t pid, char **unit) {
+        int r;
+        char *cgroup, *p, *at, *b;
+        size_t k;
+
+        assert(pid >= 0);
+        assert(unit);
+
+        r = cg_pid_get_cgroup(pid, NULL, &cgroup);
+        if (r < 0)
+                return r;
+
+        if (!startswith(cgroup, "/system/")) {
+                free(cgroup);
+                return -ENOENT;
+        }
+
+        p = cgroup + 8;
+        k = strcspn(p, "/");
+
+        at = memchr(p, '@', k);
+        if (at && at[1] == '.') {
+                size_t j;
+
+                /* This is a templated service */
+                if (p[k] != '/') {
+                        free(cgroup);
+                        return -EIO;
+                }
+
+                j = strcspn(p+k+1, "/");
+
+                b = malloc(k + j + 1);
+
+                if (b) {
+                        memcpy(b, p, at - p + 1);
+                        memcpy(b + (at - p) + 1, p + k + 1, j);
+                        memcpy(b + (at - p) + 1 + j, at + 1, k - (at - p) - 1);
+                        b[k+j] = 0;
+                }
+        } else
+                  b = strndup(p, k);
+
+        free(cgroup);
+
+        if (!b)
+                return -ENOMEM;
+
+        *unit = b;
+        return 0;
+
+}

src/shared/cgroup-util.h

@@ -69,6 +69,8 @@ int cg_is_empty(const char *controller, const char *path, bool ignore_self);
 int cg_is_empty_recursive(const char *controller, const char *path, bool ignore_self);
 
 int cg_get_user_path(char **path);
+int cg_pid_get_cgroup(pid_t pid, char **root, char **cgroup);
+int cg_pid_get_unit(pid_t pid, char **unit);
 
 char **cg_shorten_controllers(char **controllers);