From 7b0123dd6a06a032516cce66d82c064b1d942013 Mon Sep 17 00:00:00 2001
From: shafouz <38974831+shafouz@users.noreply.github.com>
Date: Sun, 13 Aug 2023 02:14:08 -0400
Subject: [PATCH] feat(remote): avoid --remote-ui infinite loop (#24465)

---
 src/nvim/main.c                       |  5 +++++
 test/functional/core/startup_spec.lua | 13 +++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/nvim/main.c b/src/nvim/main.c
index 377b804661..d9ca82784f 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -921,6 +921,11 @@ static void remote_request(mparm_T *params, int remote_args, char *server_addr,
       os_errmsg(connect_error);
       os_errmsg("\n");
       os_exit(1);
+    } else if (strequal(server_addr, os_getenv("NVIM"))) {
+      os_errmsg("Cannot attach UI of :terminal child to its parent. ");
+      os_errmsg("(Unset $NVIM to skip this check)");
+      os_errmsg("\n");
+      os_exit(1);
     }
 
     ui_client_channel_id = chan;
diff --git a/test/functional/core/startup_spec.lua b/test/functional/core/startup_spec.lua
index fb30ddebb9..94ec3d4907 100644
--- a/test/functional/core/startup_spec.lua
+++ b/test/functional/core/startup_spec.lua
@@ -41,6 +41,19 @@ describe('startup', function()
     ok(string.find(alter_slashes(meths.get_option_value('runtimepath', {})), funcs.stdpath('config'), 1, true) == nil)
   end)
 
+  it('prevents remote UI infinite loop', function()
+    clear()
+    local screen
+    screen = Screen.new(84, 3)
+    screen:attach()
+    funcs.termopen({ nvim_prog, '-u', 'NONE', '--server', eval('v:servername'), '--remote-ui' })
+    screen:expect([[
+      ^Cannot attach UI of :terminal child to its parent. (Unset $NVIM to skip this check) |
+                                                                                          |
+                                                                                          |
+    ]])
+  end)
+
   it('--startuptime', function()
     local testfile = 'Xtest_startuptime'
     finally(function()