Further progress towards Godot 4.0 support

- Primary example scenes (menu, terminal, and asciicast) working but
  still a lot of warning/error messages and some regressions.
- Editor integrated terminal works, but still a lot of warning/error
  messages and some regressions.
- Added support for "blink" display attribute.
- Removed GDScript terminal code. Terminal node is now purely a
  GDExtension. So is LibuvUtils.
- GUT tests not working yet.
- Still a lot of things to fix.
- So far, only built for and manually tested on Linux x86_64.

addons/godot_xterm/nodes/pty/libuv_utils.gd

@@ -1,36 +0,0 @@
-# Copyright (c) 2021, Leroy Hopson (MIT License)
-
-@tool
-extends Object
-# Wrapper around libuv utility functions.
-# GDNative does not currently support registering static functions so we fake it.
-# Only the static functions of this class should be called.
-
-
-static func get_os_environ() -> Dictionary:
-	# While Godot has OS.get_environment(), I could see a way to get all environent
-	# variables, other than by OS.execute() which would require to much platform
-	# specific code. Easier to use libuv's utility function.
-	return LibuvUtils.get_os_environ()
-
-
-static func get_cwd() -> String:
-	# Use uv_cwd() rather than Directory.get_current_dir() because the latter
-	# defaults to res:// even if starting godot from a different directory.
-	return LibuvUtils.new().get_cwd()
-
-
-static func get_windows_build_number() -> int:
-	assert(OS.get_name() == "Windows") #,"This function is only supported checked Windows.")
-	var release: String = LibuvUtils.new().get_os_release()
-	assert(false) #,"Not implemented.")
-	return 0
-
-
-static func kill(pid: int, signum: int):
-	if pid > 1:
-		return LibuvUtils.new().kill(pid, signum)
-
-
-static func new():
-	assert(false) #,"Abstract sealed (i.e. static) class should not be instantiated.")

addons/godot_xterm/nodes/pty/unix/pty_unix.gd

@@ -64,7 +64,10 @@ var _exit_cb: Callable
 # Writes data to the socket.
 # data: The data to write.
 func write(data) -> void:
-	assert(data is PackedByteArray or data is String, "Invalid type for argument 'data'. Should be of type PackedByteArray or String")
+	var correct_type: bool = data is PackedByteArray or data is String
+	var err_message := "Invalid type for argument 'data'. Should be of type PackedByteArray or String"
+	assert(correct_type, err_message)
+
 	if _pipe:
 		_pipe.write(data if data is PackedByteArray else data.to_utf8_buffer())
 
@@ -88,7 +91,7 @@ func _parse_env(env: Dictionary = {}) -> PackedStringArray:
 	for key in keys:
 		var value = env[key]
 		var valid = key is String and value is String
-		assert(valid) #,"Env key/value pairs must be of type String/String.")
+		assert(valid)  #,"Env key/value pairs must be of type String/String.")
 
 		if not valid:
 			push_warning("Skipping invalid env key/value pair.")
@@ -129,9 +132,23 @@ func fork(
 	_exit_cb = Callable(self, "on_exit")
 
 	# Actual fork.
-	var result = PTYUnix.new().fork(
-		# VERY IMPORTANT: The second argument must be 0, otherwise will get an ENOTSOCK error after connecting our pipe to the fd.
-		file, 0, args, parsed_env, cwd, cols, rows, uid, gid, utf8, _exit_cb
+	var result = (
+		PTYUnix
+		. new()
+		. fork(
+			# VERY IMPORTANT: The second argument must be 0, otherwise will get an ENOTSOCK error after connecting our pipe to the fd.
+			file,
+			0,
+			args,
+			parsed_env,
+			cwd,
+			cols,
+			rows,
+			uid,
+			gid,
+			utf8,
+			_exit_cb
+		)
 	)
 
 	if result[0] != OK:
@@ -146,10 +163,10 @@ func fork(
 	_pid = result[1].pid
 
 	_pipe = Pipe.new()
-	_pipe.open(_fd, true) # FIXME: _pipe.open(_fd) should be sufficient but requires two args.
+	_pipe.open(_fd, false)
 
 	# Must connect to signal AFTER opening, otherwise we will get error ENOTSOCK.
-	_pipe.connect("data_received",Callable(self,"_on_pipe_data_received"))
+	_pipe.connect("data_received", Callable(self, "_on_pipe_data_received"))
 
 	return OK
 
@@ -159,7 +176,7 @@ func open(cols: int = DEFAULT_COLS, rows: int = DEFAULT_ROWS) -> Array:
 
 
 func _exit_tree():
-	_exit_cb = null
+	_exit_cb = Callable()
 	if _pid > 1:
 		LibuvUtils.kill(_pid, IPCSignal.SIGHUP)
 		if _pipe:

addons/godot_xterm/nodes/terminal/viewport.gd

@@ -1,2 +0,0 @@
-@tool
-extends SubViewport

addons/godot_xterm/nodes/terminal/viewport.tscn

@@ -1,23 +0,0 @@
-[gd_scene load_steps=2 format=3 uid="uid://c62updkby54f3"]
-
-[sub_resource type="GDScript" id="GDScript_d8lvm"]
-script/source = "@tool
-extends SubViewport
-"
-
-[node name="SubViewport" type="SubViewport"]
-transparent_bg = true
-handle_input_locally = false
-gui_snap_controls_to_pixels = false
-size = Vector2i(2, 2)
-render_target_clear_mode = 1
-script = SubResource("GDScript_d8lvm")
-
-[node name="Terminal" type="Terminal" parent="."]
-anchors_preset = 15
-anchor_right = 1.0
-anchor_bottom = 1.0
-offset_right = -2.0
-offset_bottom = -2.0
-grow_horizontal = 2
-grow_vertical = 2