fix(cmdwin): handle control characters properly #40488

- Replace newlines in the current cmdline with NULs when opening cmdwin,
  and do the reverse when putting a cmdwin line back into the cmdline.
- Escape control characters with Ctrl-V when feeding cmdline.

runtime/lua/vim/_core/cmdwin.lua

@@ -81,9 +81,10 @@ function M.open(type, init_line, init_col)
   vim.wo[win][0].statuscolumn = '%#NonText#' .. type
 
   local filled = fill_history(buf, type)
+  init_line = init_line and init_line:gsub('\n', '\0') or ''
 
   -- Append the in-flight cmdline as the last line (or only line if history is empty).
-  vim.api.nvim_buf_set_lines(buf, filled and -1 or 0, -1, false, { init_line or '' })
+  vim.api.nvim_buf_set_lines(buf, filled and -1 or 0, -1, false, { init_line })
   local last = vim.api.nvim_buf_line_count(buf)
   vim.api.nvim_win_set_cursor(win, { last, math.max(0, (init_col or 1) - 1) })
 
@@ -92,6 +93,11 @@ function M.open(type, init_line, init_col)
     vim.bo[buf].filetype = 'vim'
   end
 
+  if vim.o.wildchar == ('\t'):byte() then
+    vim.keymap.set('i', '<Tab>', '<C-X><C-V>', { buf = buf })
+    vim.keymap.set('n', '<Tab>', 'a<C-X><C-V>', { buf = buf })
+  end
+
   vim.api.nvim__cmdwin_set(type, buf) -- Update the C-side globals.
 
   state = {
@@ -155,6 +161,7 @@ function M.confirm()
     return
   end
   local line, type = _close()
+  line = line:gsub('%z', '\n'):gsub('(%c)', '\022%1') -- Escape control characters.
   vim.api.nvim_feedkeys(type .. line .. vim.keycode('<CR>'), 'nt', false)
 end
 
@@ -164,6 +171,7 @@ function M.cancel()
     return
   end
   local line, type = _close()
+  line = line:gsub('%z', '\n'):gsub('(%c)', '\022%1') -- Escape control characters.
   vim.api.nvim_feedkeys(type .. line, 'nt', false)
 end
 

test/functional/editor/cmdwin_spec.lua

@@ -81,13 +81,6 @@ describe('cmdwin', function()
     eq(2, fn.histnr('cmd')) -- History unchanged (the in-flight cmdline was not added).
   end)
 
-  it('history entry with literal newline char', function()
-    fn.histadd(':', 'echo \n x')
-    feed('q:')
-    eq(':', fn.getcmdwintype())
-    eq('echo \0 x', api.nvim_buf_get_lines(0, 0, 1, false)[1])
-  end)
-
   it('<C-C> in normal mode cancels without executing', function()
     feed('q:')
     feed('ilet g:executed = 1<Esc>')
@@ -102,6 +95,28 @@ describe('cmdwin', function()
     eq(':', fn.getcmdtype())
   end)
 
+  it('history entry or current cmdline with control chars', function()
+    local firstbuf = api.nvim_get_current_buf()
+    local cmdline = 'normal! \023\022ifoo\nbar\027' -- Ctrl-W Ctrl-V ifoo\nbar Esc
+    local bufline = cmdline:gsub('\n', '\0')
+    fn.histadd(':', cmdline)
+    feed('q:')
+    eq(':', fn.getcmdwintype())
+    eq({ bufline, '' }, api.nvim_buf_get_lines(0, 0, -1, false))
+    api.nvim_win_set_cursor(0, { 1, 0 })
+    feed('<C-C>')
+    eq(cmdline, fn.getcmdline())
+    eq(':', fn.getcmdtype())
+    eq({ firstbuf }, fn.tabpagebuflist())
+    feed('<C-F>')
+    n.poke_eventloop()
+    eq(':', fn.getcmdwintype())
+    eq({ bufline, bufline }, api.nvim_buf_get_lines(0, 0, -1, false))
+    feed('<CR>')
+    eq({ firstbuf, firstbuf }, fn.tabpagebuflist())
+    eq({ 'foo', 'bar' }, api.nvim_buf_get_lines(0, 0, -1, false))
+  end)
+
   it('async API calls work while cmdwin is open #40312', function()
     feed('q:')
     eq(':', fn.getcmdwintype())