vim-patch:8.0.0096: has('ttyin'), has('ttyout')

Nvim note: intentionally did not include `--ttyfail` since its purpose
is not clear. (And it isn't used in any Vim test files/scripts).

---

Problem:    When the input or output is not a tty Vim appears to hang.
Solution:   Add the --ttyfail argument.  Also add the "ttyin" and "ttyout"
            features to be able to check in Vim script.

https://github.com/vim/vim/commit/2cab0e191055a8145ccd46cd52869fbb9798b971

4 files changed, 24 insertions, 15 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 300bdd061e..271adc833d 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -8317,6 +8317,8 @@ termresponse		Compiled with support for |t_RV| and |v:termresponse|.
 textobjects		Compiled with support for |text-objects|.
 timers			Compiled with |timer_start()| support.
 title			Compiled with window title support |'title'|.
+ttyin			input is a terminal (tty)
+ttyout			output is a terminal (tty)
 unix			Unix version of Vim.
 unnamedplus		Compiled with support for "unnamedplus" in 'clipboard'
 user_commands		User-defined commands.
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index c7cb51ac29..9752851d4e 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -10672,6 +10672,10 @@ static void f_has(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       n = has_nvim_version(name + 5);
     } else if (STRICMP(name, "vim_starting") == 0) {
       n = (starting != 0);
+    } else if (STRICMP(name, "ttyin") == 0) {
+      n = stdin_isatty;
+    } else if (STRICMP(name, "ttyout") == 0) {
+      n = stdout_isatty;
     } else if (STRICMP(name, "multi_byte_encoding") == 0) {
       n = has_mbyte != 0;
 #if defined(USE_ICONV) && defined(DYNAMIC_ICONV)
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 0f3e132bc0..8f804ff888 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -564,21 +564,22 @@ EXTERN int ru_col;              /* column for ruler */
 EXTERN int ru_wid;              /* 'rulerfmt' width of ruler when non-zero */
 EXTERN int sc_col;              /* column for shown command */
 
-/*
- * When starting or exiting some things are done differently (e.g. screen
- * updating).
- */
+//
+// When starting or exiting some things are done differently (e.g. screen
+// updating).
+//
+
+// First NO_SCREEN, then NO_BUFFERS, then 0 when startup finished.
 EXTERN int starting INIT(= NO_SCREEN);
-/* first NO_SCREEN, then NO_BUFFERS and then
- * set to 0 when starting up finished */
-EXTERN int exiting INIT(= FALSE);
-/* TRUE when planning to exit Vim.  Might
- * still keep on running if there is a changed
- * buffer. */
-// volatile because it is used in signal handler deathtrap().
+// true when planning to exit. Might keep running if there is a changed buffer.
+EXTERN int exiting INIT(= false);
+// is stdin a terminal?
+EXTERN int stdin_isatty INIT(= true);
+// is stdout a terminal?
+EXTERN int stdout_isatty INIT(= true);
+// true when doing full-screen output, otherwise only writing some messages.
+// volatile because it is used in a signal handler.
 EXTERN volatile int full_screen INIT(= false);
-// TRUE when doing full-screen output
-// otherwise only writing some messages
 
 EXTERN int restricted INIT(= FALSE);
 // TRUE when started in restricted mode (-Z)
diff --git a/src/nvim/main.c b/src/nvim/main.c
index ea7a58bda3..93afe11f3a 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1240,8 +1240,10 @@ static void init_startuptime(mparm_T *paramp)
 
 static void check_and_set_isatty(mparm_T *paramp)
 {
-  paramp->input_isatty = os_isatty(fileno(stdin));
-  paramp->output_isatty = os_isatty(fileno(stdout));
+  stdin_isatty
+    = paramp->input_isatty = os_isatty(fileno(stdin));
+  stdout_isatty
+    = paramp->output_isatty = os_isatty(fileno(stdout));
   paramp->err_isatty = os_isatty(fileno(stderr));
   TIME_MSG("window checked");
 }