Clean up stale Wayland socket on shutdown, crash, and startup

tabbed-wlroots.c

@@ -166,6 +166,7 @@ struct tabbed_host {
 static struct tabbed_server server;
 static struct tabbed_host host;
 static char tabbed_socket[64];
+static char socket_path[256];
 static volatile sig_atomic_t needs_redraw;
 static bool frame_pending;
 static bool shutting_down;
@@ -248,6 +249,18 @@ static void terminate_clients(void) {
     }
 }
 
+/* Remove the session's Wayland socket file (and its companion .lock file,
+   both created by wl_display_add_socket), if present.  The full path is
+   precomputed at startup so this only ever calls unlink()/snprintf(), which
+   are async-signal-safe and therefore safe from the signal/crash handlers
+   too.  A missing file is fine: ENOENT is ignored, i.e. nothing to clean. */
+static void remove_socket_file(void) {
+    unlink(socket_path);
+    char lock_path[sizeof(socket_path) + 6];
+    snprintf(lock_path, sizeof(lock_path), "%s.lock", socket_path);
+    unlink(lock_path);
+}
+
 /* Full shutdown of the nested session: take down the clients first, then
    free our own allocations and exit. Guarded so the various close paths
    (host window close, last tab closed) only run once. */
@@ -261,6 +274,7 @@ static void shutdown_cleanup(void) {
     }
     if (server.xkb_keymap) xkb_keymap_unref(server.xkb_keymap);
     if (server.xkb_ctx) xkb_context_unref(server.xkb_ctx);
+    remove_socket_file();
 }
 
 /* ===================== EGL helpers ===================== */
@@ -1924,6 +1938,7 @@ static void crash_handler(int sig, siginfo_t *info, void *ctx) {
     int n = backtrace(bt, 64);
     write(2, "\n=== BACKTRACE ===\n", 19);
     backtrace_symbols_fd(bt, n, 2);
+    remove_socket_file();
     _exit(139);
 }
 
@@ -1963,6 +1978,12 @@ static void sigusr1_handler(int sig) {
 int main(int argc, char *argv[]) {
     snprintf(tabbed_socket, sizeof(tabbed_socket), "tabbed-wayland-%d",
              (int)getpid());
+    const char *runtime = getenv("XDG_RUNTIME_DIR");
+    if (!runtime) runtime = "/tmp";
+    snprintf(socket_path, sizeof(socket_path), "%s/%s", runtime, tabbed_socket);
+    /* Clear a stale leftover (e.g. from a crashed previous run with the same
+       name) before we try to bind; harmless if there is none. */
+    remove_socket_file();
 
     /* Resolve TABBED_LOG up front so signal handlers can read the cached
        level without touching non-async-signal-safe functions. */
@@ -2092,6 +2113,7 @@ int main(int argc, char *argv[]) {
     /* Now connect to the host compositor and present inside it. */
     if (!host_init()) {
         fprintf(stderr, "tabbed-wlroots: could not start nested session\n");
+        remove_socket_file();
         return 1;
     }
 
@@ -2104,6 +2126,7 @@ int main(int argc, char *argv[]) {
                 "takes args, e.g. \"firefox -no-remote\".\n"
                 "       Arguments written bare (starting with '-') launch a "
                 "bogus extra tab.\n", argv[0]);
+        remove_socket_file();
         return 1;
     }
     if (total_apps > MAX_APPS) total_apps = MAX_APPS;