- manager_get_session_by_pid(m, leader, &session);
- if (session) {
- _cleanup_free_ char *path = NULL;
- _cleanup_close_ int fifo_fd = -1;
-
- /* Session already exists, client is probably
- * something like "su" which changes uid but is still
- * the same session */
-
- fifo_fd = session_create_fifo(session);
- if (fifo_fd < 0)
- return fifo_fd;
-
- path = session_bus_path(session);
- if (!path)
- return -ENOMEM;
-
- log_debug("Sending reply about an existing session: "
- "id=%s object_path=%s uid=%u runtime_path=%s "
- "session_fd=%d seat=%s vtnr=%u",
- session->id,
- path,
- (uint32_t) session->user->uid,
- session->user->runtime_path,
- fifo_fd,
- session->seat ? session->seat->id : "",
- (uint32_t) session->vtnr);
-
- return sd_bus_reply_method_return(
- message, "soshusub",
- session->id,
- path,
- session->user->runtime_path,
- fifo_fd,
- (uint32_t) session->user->uid,
- session->seat ? session->seat->id : "",
- (uint32_t) session->vtnr,
- true);
- }
+ r = manager_get_session_by_pid(m, leader, NULL);
+ if (r > 0)
+ return sd_bus_error_setf(error, BUS_ERROR_SESSION_BUSY, "Already running in a session");
+
+ /*
+ * Old gdm and lightdm start the user-session on the same VT as
+ * the greeter session. But they destroy the greeter session
+ * after the user-session and want the user-session to take
+ * over the VT. We need to support this for
+ * backwards-compatibility, so make sure we allow new sessions
+ * on a VT that a greeter is running on. Furthermore, to allow
+ * re-logins, we have to allow a greeter to take over a used VT for
+ * the exact same reasons.
+ */
+ if (c != SESSION_GREETER &&
+ vtnr > 0 &&
+ vtnr < m->seat0->position_count &&
+ m->seat0->positions[vtnr] &&
+ m->seat0->positions[vtnr]->class != SESSION_GREETER)
+ return sd_bus_error_setf(error, BUS_ERROR_SESSION_BUSY, "Already occupied by a session");