5 files changed, 64 insertions, 1 deletions

diff --git a/src/nvim/auevents.lua b/src/nvim/auevents.lua
index 11d1597236..b931907fe3 100644
--- a/src/nvim/auevents.lua
+++ b/src/nvim/auevents.lua
@@ -109,6 +109,7 @@ return {
     'TermEnter', -- after entering Terminal mode
     'TermLeave', -- after leaving Terminal mode
     'TermOpen', -- after opening a terminal buffer
+    'TermRequest', -- after an unhandled OSC sequence is emitted
     'TermResponse', -- after setting "v:termresponse"
     'TextChanged', -- text was modified
     'TextChangedI', -- text was modified in Insert mode(no popup)
@@ -166,6 +167,7 @@ return {
     TabNewEntered = true,
     TermClose = true,
     TermOpen = true,
+    TermRequest = true,
     UIEnter = true,
     UILeave = true,
   },
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 5069f00df0..451e258356 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -185,6 +185,7 @@ static struct vimvar {
   VV(VV_VERSION,          "version",          VAR_NUMBER, VV_COMPAT + VV_RO),
   VV(VV_LNUM,             "lnum",             VAR_NUMBER, VV_RO_SBX),
   VV(VV_TERMRESPONSE,     "termresponse",     VAR_STRING, VV_RO),
+  VV(VV_TERMREQUEST,      "termrequest",      VAR_STRING, VV_RO),
   VV(VV_FNAME,            "fname",            VAR_STRING, VV_RO),
   VV(VV_LANG,             "lang",             VAR_STRING, VV_RO),
   VV(VV_LC_TIME,          "lc_time",          VAR_STRING, VV_RO),
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index c46a895c06..abe2685424 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -86,6 +86,7 @@ typedef enum {
   VV_THIS_SESSION,
   VV_VERSION,
   VV_LNUM,
+  VV_TERMREQUEST,
   VV_TERMRESPONSE,
   VV_FNAME,
   VV_LANG,
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index c6a2cb3354..ee482f7104 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -169,6 +169,54 @@ static VTermScreenCallbacks vterm_screen_callbacks = {
 
 static Set(ptr_t) invalidated_terminals = SET_INIT;
 
+static void emit_term_request(void **argv)
+{
+  char *payload = argv[0];
+  size_t payload_length = (size_t)argv[1];
+
+  String termrequest = { .data = payload, .size = payload_length };
+  Object data = STRING_OBJ(termrequest);
+  set_vim_var_string(VV_TERMREQUEST, payload, (ptrdiff_t)payload_length);
+  apply_autocmds_group(EVENT_TERMREQUEST, NULL, NULL, false, AUGROUP_ALL, curbuf, NULL, &data);
+  xfree(payload);
+}
+
+static int on_osc(int command, VTermStringFragment frag, void *user)
+{
+  if (frag.str == NULL) {
+    return 0;
+  }
+
+  StringBuilder request = KV_INITIAL_VALUE;
+  kv_printf(request, "\x1b]%d;", command);
+  kv_concat_len(request, frag.str, frag.len);
+  multiqueue_put(main_loop.events, emit_term_request, request.items, (void *)request.size);
+  return 1;
+}
+
+static int on_dcs(const char *command, size_t commandlen, VTermStringFragment frag, void *user)
+{
+  if ((command == NULL) || (frag.str == NULL)) {
+    return 0;
+  }
+
+  StringBuilder request = KV_INITIAL_VALUE;
+  kv_printf(request, "\x1bP%*s", (int)commandlen, command);
+  kv_concat_len(request, frag.str, frag.len);
+  multiqueue_put(main_loop.events, emit_term_request, request.items, (void *)request.size);
+  return 1;
+}
+
+static VTermStateFallbacks vterm_fallbacks = {
+  .control = NULL,
+  .csi = NULL,
+  .osc = on_osc,
+  .dcs = on_dcs,
+  .apc = NULL,
+  .pm = NULL,
+  .sos = NULL,
+};
+
 void terminal_init(void)
 {
   time_watcher_init(&main_loop, &refresh_timer, NULL);
@@ -222,6 +270,7 @@ void terminal_open(Terminal **termpp, buf_T *buf, TerminalOptions opts)
   vterm_screen_enable_reflow(rv->vts, true);
   // delete empty lines at the end of the buffer
   vterm_screen_set_callbacks(rv->vts, &vterm_screen_callbacks, rv);
+  vterm_screen_set_unrecognised_fallbacks(rv->vts, &vterm_fallbacks, rv);
   vterm_screen_set_damage_merge(rv->vts, VTERM_DAMAGE_SCROLL);
   vterm_screen_reset(rv->vts, 1);
   vterm_output_set_callback(rv->vt, term_output_callback, rv);
diff --git a/src/nvim/vvars.lua b/src/nvim/vvars.lua
index d1b5e13401..6410df1a57 100644
--- a/src/nvim/vvars.lua
+++ b/src/nvim/vvars.lua
@@ -770,13 +770,23 @@ M.vars = {
     desc = 'Value of |String| type.  Read-only.  See: |type()|',
   },
   termresponse = {
+    type = 'string',
     desc = [=[
-      The value of the most recent OSC or DCS escape sequence
+      The value of the most recent OSC or DCS control sequence
       received by Nvim from the terminal. This can be read in a
       |TermResponse| event handler after querying the terminal using
       another escape sequence.
     ]=],
   },
+  termrequest = {
+    type = 'string',
+    desc = [=[
+      The value of the most recent OSC or DCS control sequence
+      sent from a process running in the embedded |terminal|.
+      This can be read in a |TermRequest| event handler to respond
+      to queries from embedded applications.
+    ]=],
+  },
   testing = {
     desc = [=[
       Must be set before using `test_garbagecollect_now()`.