fix(tui): handle padding requirements for visual bell (neovim#20238)

src/nvim/event/loop.c

@@ -31,41 +31,57 @@ void loop_init(Loop *loop, void *data)
   loop->poll_timer.data = xmalloc(sizeof(bool));  // "timeout expired" flag
 }
 
-/// Processes one `Loop.uv` event (at most).
-/// Processes all `Loop.fast_events` events.
-/// Does NOT process `Loop.events`, that is an application-specific decision.
+/// Process `Loop.uv` events with a timeout.
 ///
 /// @param loop
-/// @param ms   0: non-blocking poll.
-///            >0: timeout after `ms`.
-///            <0: wait forever.
-/// @returns true if `ms` timeout was reached
-bool loop_poll_events(Loop *loop, int ms)
+/// @param ms  0: non-blocking poll.
+///            > 0: timeout after `ms`.
+///            < 0: wait forever.
+/// @param once  true: process at most one `Loop.uv` event.
+///              false: process until `ms` timeout (only has effect if `ms` > 0).
+/// @return  true if `ms` > 0 and was reached
+bool loop_uv_run(Loop *loop, int ms, bool once)
 {
   if (loop->recursive++) {
     abort();  // Should not re-enter uv_run
   }
 
   uv_run_mode mode = UV_RUN_ONCE;
-  bool timeout_expired = false;
+  bool *timeout_expired = loop->poll_timer.data;
+  *timeout_expired = false;
 
   if (ms > 0) {
-    *((bool *)loop->poll_timer.data) = false;  // reset "timeout expired" flag
-    // Dummy timer to ensure UV_RUN_ONCE does not block indefinitely for I/O.
+    // This timer ensures UV_RUN_ONCE does not block indefinitely for I/O.
     uv_timer_start(&loop->poll_timer, timer_cb, (uint64_t)ms, (uint64_t)ms);
   } else if (ms == 0) {
     // For ms == 0, do a non-blocking event poll.
     mode = UV_RUN_NOWAIT;
   }
 
-  uv_run(&loop->uv, mode);
+  do {
+    uv_run(&loop->uv, mode);
+  } while (ms > 0 && !once && !*timeout_expired);
 
   if (ms > 0) {
-    timeout_expired = *((bool *)loop->poll_timer.data);
     uv_timer_stop(&loop->poll_timer);
   }
 
   loop->recursive--;  // Can re-enter uv_run now
+  return *timeout_expired;
+}
+
+/// Processes one `Loop.uv` event (at most).
+/// Processes all `Loop.fast_events` events.
+/// Does NOT process `Loop.events`, that is an application-specific decision.
+///
+/// @param loop
+/// @param ms  0: non-blocking poll.
+///            > 0: timeout after `ms`.
+///            < 0: wait forever.
+/// @return  true if `ms` > 0 and was reached
+bool loop_poll_events(Loop *loop, int ms)
+{
+  bool timeout_expired = loop_uv_run(loop, ms, true);
   multiqueue_process_events(loop->fast_events);
   return timeout_expired;
 }

src/nvim/tui/tui.c

@@ -1616,7 +1616,7 @@ static void unibi_goto(UI *ui, int row, int col)
       memset(&vars, 0, sizeof(vars)); \
       data->cork = true; \
 retry: \
-      unibi_format(vars, vars + 26, str, data->params, out, ui, NULL, NULL); \
+      unibi_format(vars, vars + 26, str, data->params, out, ui, pad, ui); \
       if (data->overflow) { \
         data->bufpos = orig_pos; \
         flush_buf(ui); \
@@ -1647,6 +1647,7 @@ static void out(void *ctx, const char *str, size_t len)
 
   if (len > available) {
     if (data->cork) {
+      // Called by unibi_format(): avoid flush_buf() halfway an escape sequence.
       data->overflow = true;
       return;
     } else {
@@ -1658,6 +1659,30 @@ static void out(void *ctx, const char *str, size_t len)
   data->bufpos += len;
 }
 
+/// Called by unibi_format() for padding instructions.
+/// The following parameter descriptions are extracted from unibi_format(3) and terminfo(5).
+///
+/// @param ctx    the same as `ctx2` passed to unibi_format()
+/// @param delay  the delay in tenths of milliseconds
+/// @param scale  padding is proportional to the number of lines affected
+/// @param force  padding is mandatory
+static void pad(void *ctx, size_t delay, int scale FUNC_ATTR_UNUSED, int force)
+{
+  if (!force) {
+    return;
+  }
+
+  UI *ui = ctx;
+  TUIData *data = ui->data;
+
+  if (data->overflow) {
+    return;
+  }
+
+  flush_buf(ui);
+  loop_uv_run(data->loop, (int)(delay / 10), false);
+}
+
 static void unibi_set_if_empty(unibi_term *ut, enum unibi_string str, const char *val)
 {
   if (!unibi_get_str(ut, str)) {