TUI: set os/input.c:global_fd to input->in_fd #10174

Problem: When we changed startup to wait for the TUI (like a remote UI),
         we forgot to set os/input.c:global_fd.  That used to be done by
         input_start().

Solution: Initialize os/input.c:global_fd before initializing libtermkey
          (termkey_new_abstract) so that tui_get_stty_erase() and
          friends can inspect the correct fd.

fixes #10134
close #10174

src/nvim/os/input.c

@@ -50,6 +50,11 @@ void input_init(void)
   input_buffer = rbuffer_new(INPUT_BUFFER_SIZE + MAX_KEY_CODE_LEN);
 }
 
+void input_global_fd_init(int fd)
+{
+  global_fd = fd;
+}
+
 /// Global TTY (or pipe for "-es") input stream, before UI starts.
 int input_global_fd(void)
 {
@@ -62,7 +67,7 @@ void input_start(int fd)
     return;
   }
 
-  global_fd = fd;
+  input_global_fd_init(fd);
   rstream_init_fd(&main_loop, &read_stream, fd, READ_BUFFER_SIZE);
   rstream_start(&read_stream, input_read_cb, NULL);
 }

src/nvim/tui/input.c

@@ -32,23 +32,6 @@ void tinput_init(TermInput *input, Loop *loop)
   uv_mutex_init(&input->key_buffer_mutex);
   uv_cond_init(&input->key_buffer_cond);
 
-  const char *term = os_getenv("TERM");
-  if (!term) {
-    term = "";  // termkey_new_abstract assumes non-null (#2745)
-  }
-
-#if TERMKEY_VERSION_MAJOR > 0 || TERMKEY_VERSION_MINOR > 18
-  input->tk = termkey_new_abstract(term,
-                                   TERMKEY_FLAG_UTF8 | TERMKEY_FLAG_NOSTART);
-  termkey_hook_terminfo_getstr(input->tk, input->tk_ti_hook_fn, NULL);
-  termkey_start(input->tk);
-#else
-  input->tk = termkey_new_abstract(term, TERMKEY_FLAG_UTF8);
-#endif
-
-  int curflags = termkey_get_canonflags(input->tk);
-  termkey_set_canonflags(input->tk, curflags | TERMKEY_CANON_DELBS);
-
   // If stdin is not a pty, switch to stderr. For cases like:
   //    echo q | nvim -es
   //    ls *.md | xargs nvim
@@ -67,6 +50,24 @@ void tinput_init(TermInput *input, Loop *loop)
     input->in_fd = 2;
   }
 #endif
+  input_global_fd_init(input->in_fd);
+
+  const char *term = os_getenv("TERM");
+  if (!term) {
+    term = "";  // termkey_new_abstract assumes non-null (#2745)
+  }
+
+#if TERMKEY_VERSION_MAJOR > 0 || TERMKEY_VERSION_MINOR > 18
+  input->tk = termkey_new_abstract(term,
+                                   TERMKEY_FLAG_UTF8 | TERMKEY_FLAG_NOSTART);
+  termkey_hook_terminfo_getstr(input->tk, input->tk_ti_hook_fn, NULL);
+  termkey_start(input->tk);
+#else
+  input->tk = termkey_new_abstract(term, TERMKEY_FLAG_UTF8);
+#endif
+
+  int curflags = termkey_get_canonflags(input->tk);
+  termkey_set_canonflags(input->tk, curflags | TERMKEY_CANON_DELBS);
 
   // setup input handle
   rstream_init_fd(loop, &input->read_stream, input->in_fd, 0xfff);

test/functional/terminal/tui_spec.lua

@@ -268,14 +268,13 @@ describe('TUI', function()
   end)
 end)
 
-describe('TUI with non-tty file descriptors', function()
+describe('TUI', function()
-  before_each(helpers.clear)
+  before_each(clear)
-
   after_each(function()
-    os.remove('testF') -- ensure test file is removed
+    os.remove('testF')
   end)
 
-  it('can handle pipes as stdout and stderr', function()
+  it('with non-tty (pipe) stdout/stderr', function()
     local screen = thelpers.screen_setup(0, '"'..nvim_prog
       ..' -u NONE -i NONE --cmd \'set noswapfile noshowcmd noruler\' --cmd \'normal iabc\' > /dev/null 2>&1 && cat testF && rm testF"')
     feed_data(':w testF\n:q\n')
@@ -289,6 +288,22 @@ describe('TUI with non-tty file descriptors', function()
       {3:-- TERMINAL --}                                    |
     ]])
   end)
+
+  it('<C-h> #10134', function()
+    local screen = thelpers.screen_setup(0, '["'..nvim_prog
+      ..[[", "-u", "NONE", "-i", "NONE", "--cmd", "set noruler", "--cmd", ':nnoremap <C-h> :echomsg "\<C-h\>"<CR>']]..']')
+
+    command([[call chansend(b:terminal_job_id, "\<C-h>")]])
+    screen:expect([[
+      {1: }                                                 |
+      {4:~                                                 }|
+      {4:~                                                 }|
+      {4:~                                                 }|
+      {5:[No Name]                                         }|
+      <C-h>                                             |
+      {3:-- TERMINAL --}                                    |
+    ]])
+  end)
 end)
 
 describe('TUI FocusGained/FocusLost', function()