vim-patch:8.2.4975: recursive command line loop may cause a crash (#18614)

Problem:    Recursive command line loop may cause a crash.
Solution:   Limit recursion of getcmdline().
https://github.com/vim/vim/commit/51f0bfb88a3554ca2dde777d78a59880d1ee37a8

Cherry-pick e_command_too_recursive from patch 8.2.3957.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 114f1e2ae5..1d496cbf25 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -804,6 +804,12 @@ static uint8_t *command_line_enter(int firstc, long count, int indent, bool init
     ccline.cmdlen = s->indent;
   }
 
+  if (cmdline_level == 50) {
+    // Somehow got into a loop recursively calling getcmdline(), bail out.
+    emsg(_(e_command_too_recursive));
+    goto theend;
+  }
+
   ExpandInit(&s->xpc);
   ccline.xpc = &s->xpc;
 
@@ -995,12 +1001,13 @@ static uint8_t *command_line_enter(int firstc, long count, int indent, bool init
   State = s->save_State;
   setmouse();
   ui_cursor_shape();            // may show different cursor shape
+  sb_text_end_cmdline();
+
+theend:
   xfree(s->save_p_icm);
   xfree(ccline.last_colors.cmdbuff);
   kv_destroy(ccline.last_colors.colors);
 
-  sb_text_end_cmdline();
-
   char_u *p = ccline.cmdbuff;
 
   if (ui_has(kUICmdline)) {