-static int session_link_x11_socket(Session *s) {
- _cleanup_free_ char *t = NULL, *f = NULL;
- char *c;
- size_t k;
-
- assert(s);
- assert(s->user);
- assert(s->user->runtime_path);
-
- if (s->user->display)
- return 0;
-
- if (!s->display || !display_is_local(s->display))
- return 0;
-
- k = strspn(s->display+1, "0123456789");
- f = new(char, sizeof("/tmp/.X11-unix/X") + k);
- if (!f)
- return log_oom();
-
- c = stpcpy(f, "/tmp/.X11-unix/X");
- memcpy(c, s->display+1, k);
- c[k] = 0;
-
- if (access(f, F_OK) < 0) {
- log_warning("Session %s has display %s with non-existing socket %s.", s->id, s->display, f);
- return -ENOENT;
- }
-
- /* Note that this cannot be in a subdir to avoid
- * vulnerabilities since we are privileged but the runtime
- * path is owned by the user */
-
- t = strappend(s->user->runtime_path, "/X11-display");
- if (!t)
- return log_oom();
-
- if (link(f, t) < 0) {
- if (errno == EEXIST) {
- unlink(t);
-
- if (link(f, t) >= 0)
- goto done;
- }
-
- if (symlink(f, t) < 0) {
-
- if (errno == EEXIST) {
- unlink(t);
-
- if (symlink(f, t) >= 0)
- goto done;
- }
-
- log_error("Failed to link %s to %s: %m", f, t);
- return -errno;
- }
- }
-
-done:
- log_info("Linked %s to %s.", f, t);
- s->user->display = s;
-
- return 0;
-}
-