fix(ui): re-organize tty fd handling and fix issues

- Use the correct fd to replace stdin on windows (CONIN)
- Don't start the TUI if there are no tty fd (not a regression,
  but makes sense regardless)
- De-mythologize "global input fd". it is just STDIN.

2 files changed, 8 insertions, 19 deletions

diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index b837a380d5..91fbdf7886 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -153,19 +153,7 @@ void tinput_init(TermInput *input, Loop *loop)
                               kitty_key_map_entry[i].name);
   }
 
-  // If stdin is not a pty, switch to stderr. For cases like:
-  //    echo q | nvim -es
-  //    ls *.md | xargs nvim
-#ifdef MSWIN
-  if (!os_isatty(input->in_fd)) {
-    input->in_fd = os_get_conin_fd();
-  }
-#else
-  if (!os_isatty(input->in_fd) && os_isatty(STDERR_FILENO)) {
-    input->in_fd = STDERR_FILENO;
-  }
-#endif
-  input_global_fd_init(input->in_fd);
+  input->in_fd = STDIN_FILENO;
 
   const char *term = os_getenv("TERM");
   if (!term) {
@@ -174,7 +162,7 @@ void tinput_init(TermInput *input, Loop *loop)
 
   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_hook_terminfo_getstr(input->tk, input->tk_ti_hook_fn, input);
   termkey_start(input->tk);
 
   int curflags = termkey_get_canonflags(input->tk);
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 44f6718039..e46dc892ea 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -1342,7 +1342,7 @@ static void suspend_event(void **argv)
   TUIData *tui = argv[0];
   bool enable_mouse = tui->mouse_enabled;
   tui_terminal_stop(tui);
-  stream_set_blocking(input_global_fd(), true);   // normalize stream (#2598)
+  stream_set_blocking(tui->input.in_fd, true);   // normalize stream (#2598)
 
   kill(0, SIGTSTP);
 
@@ -1351,7 +1351,7 @@ static void suspend_event(void **argv)
   if (enable_mouse) {
     tui_mouse_on(tui);
   }
-  stream_set_blocking(input_global_fd(), false);  // libuv expects this
+  stream_set_blocking(tui->input.in_fd, false);  // libuv expects this
 }
 #endif
 
@@ -2238,12 +2238,12 @@ static void flush_buf(TUIData *tui)
 ///
 /// @see tmux/tty-keys.c fe4e9470bb504357d073320f5d305b22663ee3fd
 /// @see https://bugzilla.redhat.com/show_bug.cgi?id=142659
-static const char *tui_get_stty_erase(void)
+static const char *tui_get_stty_erase(int fd)
 {
   static char stty_erase[2] = { 0 };
 #if defined(HAVE_TERMIOS_H)
   struct termios t;
-  if (tcgetattr(input_global_fd(), &t) != -1) {
+  if (tcgetattr(fd, &t) != -1) {
     stty_erase[0] = (char)t.c_cc[VERASE];
     stty_erase[1] = '\0';
     DLOG("stty/termios:erase=%s", stty_erase);
@@ -2256,9 +2256,10 @@ static const char *tui_get_stty_erase(void)
 /// @see TermInput.tk_ti_hook_fn
 static const char *tui_tk_ti_getstr(const char *name, const char *value, void *data)
 {
+  TermInput *input = data;
   static const char *stty_erase = NULL;
   if (stty_erase == NULL) {
-    stty_erase = tui_get_stty_erase();
+    stty_erase = tui_get_stty_erase(input->in_fd);
   }
 
   if (strequal(name, "key_backspace")) {