fix(tui): detach/attach on suspend/resume (#22040)

Problem:
When a TUI client is suspended it still receives UI events from the
server, and has to process these accumulated events when it is resumed.
With mulitple TUI clients this is a bigger problem, considering the
following steps:
1. A TUI client is attached.
2. CTRL-Z is pressed and the first client is suspended.
3. Another TUI client is attached.
4. CTRL-Z is pressed and a "suspend" event is sent to both clients. The
   second client is suspended, while the first client isn't able to
   process the event because it has already been suspended.
5. The first client is resumed. It processes the accumulated "suspend"
   event and suspends immediately.

Solution:
Make a TUI client detach on suspend and re-attach on resume.

1 files changed, 21 insertions, 8 deletions

diff --git a/src/nvim/ui_client.c b/src/nvim/ui_client.c
index 378c0e4831..b5c8dff412 100644
--- a/src/nvim/ui_client.c
+++ b/src/nvim/ui_client.c
@@ -23,6 +23,7 @@
 #include "nvim/ui_client.h"
 
 static TUIData *tui = NULL;
+static bool ui_client_is_remote = false;
 
 // uncrustify:off
 #ifdef INCLUDE_GENERATED_DECLARATIONS
@@ -66,13 +67,8 @@ uint64_t ui_client_start_server(int argc, char **argv)
   return channel->id;
 }
 
-void ui_client_run(bool remote_ui)
-  FUNC_ATTR_NORETURN
+void ui_client_attach(int width, int height, char *term)
 {
-  int width, height;
-  char *term;
-  tui = tui_start(&width, &height, &term);
-
   MAXSIZE_TEMP_ARRAY(args, 3);
   ADD_C(args, INTEGER_OBJ(width));
   ADD_C(args, INTEGER_OBJ(height));
@@ -82,14 +78,14 @@ void ui_client_run(bool remote_ui)
   PUT_C(opts, "ext_linegrid", BOOLEAN_OBJ(true));
   PUT_C(opts, "ext_termcolors", BOOLEAN_OBJ(true));
   if (term) {
-    PUT(opts, "term_name", STRING_OBJ(cstr_to_string(term)));
+    PUT_C(opts, "term_name", STRING_OBJ(cstr_as_string(term)));
   }
   if (ui_client_bg_response != kNone) {
     bool is_dark = (ui_client_bg_response == kTrue);
     PUT_C(opts, "term_background", STRING_OBJ(cstr_as_string(is_dark ? "dark" : "light")));
   }
   PUT_C(opts, "term_colors", INTEGER_OBJ(t_colors));
-  if (!remote_ui) {
+  if (!ui_client_is_remote) {
     PUT_C(opts, "stdin_tty", BOOLEAN_OBJ(stdin_isatty));
     PUT_C(opts, "stdout_tty", BOOLEAN_OBJ(stdout_isatty));
     if (ui_client_forward_stdin) {
@@ -100,6 +96,23 @@ void ui_client_run(bool remote_ui)
 
   rpc_send_event(ui_client_channel_id, "nvim_ui_attach", args);
   ui_client_attached = true;
+}
+
+void ui_client_detach(void)
+{
+  rpc_send_event(ui_client_channel_id, "nvim_ui_detach", (Array)ARRAY_DICT_INIT);
+  ui_client_attached = false;
+}
+
+void ui_client_run(bool remote_ui)
+  FUNC_ATTR_NORETURN
+{
+  ui_client_is_remote = remote_ui;
+  int width, height;
+  char *term;
+  tui = tui_start(&width, &height, &term);
+
+  ui_client_attach(width, height, term);
 
   // os_exit() will be invoked when the client channel detaches
   while (true) {