Add new PTY node (replaces Pseudoterminal node)

Uses fork of node-pty native code for forking pseudoterminals.
Uses libuv pipe handle to communicate with the child process.

- Paves the way for cross-platform (Linux, macOS and Windows) support.
- Renames Pseudoterminal to PTY (which is much easier to type and spell :D).
- Better performance than the old Pseudoterminal node. Especially when
  streaming large amounts of data such as running the `yes` command.
- Allows setting custom file, args, initial window size, cwd, env vars
  (including important ones such as TERM and COLORTERM) and uid/gid
  on Linux and macOS.
- Returns process exit code and terminating signal.

addons/godot_xterm/nodes/pty/libuv_utils.gd

@@ -0,0 +1,29 @@
+# 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.
+
+const LibuvUtils := preload("./libuv_utils.gdns")
+
+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.new().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 on Windows.")
+	var release: String = LibuvUtils.new().get_os_release()
+	assert(false, "Not implemented.")
+	return 0
+
+static func new():
+	assert(false, "Abstract sealed (i.e. static) class should not be instantiated.")

addons/godot_xterm/nodes/pty/libuv_utils.gdns

@@ -0,0 +1,8 @@
+[gd_resource type="NativeScript" load_steps=2 format=2]
+
+[ext_resource path="res://addons/godot_xterm/native/godotxtermnative.gdnlib" type="GDNativeLibrary" id=1]
+
+[resource]
+resource_name = "Terminal"
+class_name = "LibuvUtils"
+library = ExtResource( 1 )

addons/godot_xterm/nodes/pty/pipe.gdns

@@ -0,0 +1,8 @@
+[gd_resource type="NativeScript" load_steps=2 format=2]
+
+[ext_resource path="res://addons/godot_xterm/native/godotxtermnative.gdnlib" type="GDNativeLibrary" id=1]
+
+[resource]
+resource_name = "Terminal"
+class_name = "Pipe"
+library = ExtResource( 1 )

addons/godot_xterm/nodes/pty/pty.gd

@@ -0,0 +1,261 @@
+# Derived from https://github.com/microsoft/node-pty/blob/main/src/terminal.ts
+# Copyright (c) 2012-2015, Christopher Jeffrey (MIT License)
+# Copyright (c) 2016, Daniel Imms (MIT License).
+# Copyright (c) 2018, Microsoft Corporation (MIT License).
+# Copyright (c) 2021, Leroy Hopson (MIT License).
+
+tool
+extends Node
+
+const LibuvUtils := preload("./libuv_utils.gd")
+const Pipe := preload("./pipe.gdns")
+const Terminal := preload("../terminal/terminal.gd")
+
+const DEFAULT_NAME := "xterm-256color"
+const DEFAULT_COLS := 80
+const DEFAULT_ROWS := 24
+const DEFAULT_ENV := {TERM = DEFAULT_NAME, COLORTERM = "truecolor"}
+
+## Default messages to indicate PAUSE/RESUME for automatic flow control.
+## To avoid conflicts with rebound XON/XOFF control codes (such as on-my-zsh),
+## the sequences can be customized in IPtyForkOptions.
+#const FLOW_CONTROL_PAUSE = char(0x13) # defaults to XOFF
+#const FLOW_CONTROL_RESUME = char(0x11) # defaults to XON
+
+enum Status { NONE, OPEN, EXITED, ERROR }
+const STATUS_NONE = Status.NONE
+const STATUS_OPEN = Status.OPEN
+const STATUS_EXITED = Status.EXITED
+const STATUS_ERROR = Status.ERROR
+
+# Any signal_number can be sent to the pty's process using the kill() function,
+# these are just the signals with numbers specified in the POSIX standard.
+enum Signal {
+	SIGHUP = 1,  # Hangup
+	SIGINT = 2,  # Terminal interrupt signal
+	SIGQUIT = 3,  # Terminal quit signal
+	SIGILL = 4,  # Illegal instruction
+	SIGTRAP = 5,  # Trace/breakpoint trap
+	SIGABRT = 6,  # Process abort signal
+	SIGFPE = 8,  # Erroneous arithmetic operation
+	SIGKILL = 9,  # Kill (cannot be caught or ignored)
+	SIGSEGV = 11,  # Invalid memory reference
+	SIGPIPE = 13,  # Write on a pipe with no one to read it
+	SIGALRM = 14,  # Alarm clock
+	SIGTERM = 15,  # Termination signal
+}
+
+signal data_received(data)
+signal exited(exit_code, signum)
+signal errored(message)
+
+export (NodePath) var terminal_path := NodePath() setget set_terminal_path
+
+var status := STATUS_NONE
+var error_string := ""
+var terminal: Terminal = null setget set_terminal
+
+## Name of the terminal to be set in environment ($TERM variable).
+#export (String) var term_name: String
+
+# The name of the process.
+var process: String
+
+# The process ID.
+var pid: int
+
+# The column size in characters.
+export (int) var cols: int = DEFAULT_COLS setget set_cols
+
+# The row size in characters.
+export (int) var rows: int = DEFAULT_ROWS setget set_rows
+
+# Working directory to be set for the child program.
+#export (String) var cwd := LibuvUtils.get_cwd()
+
+# Environment to be set for the child program.
+export (Dictionary) var env := DEFAULT_ENV
+
+# If true the environment variables in the env Dictionary will be merged with
+# the environment variables of the operating system (e.g. printenv), with the
+# former taking precedence in the case of conflicts.
+export (bool) var use_os_env := true
+
+# If true, pty will call fork() in in _ready().
+export (bool) var autostart := false
+
+# (EXPERIMENTAL)
+# If true, PTY node will create a blocking libuv loop in a new thread.
+# signals will be emitted using call_deferred.
+#export (bool) var use_threads := false
+
+## String encoding of the underlying pty.
+## If set, incoming data will be decoded to strings and outgoing strings to bytes applying this encoding.
+## If unset, incoming data will be delivered as raw bytes (PoolByteArray type).
+## By default 'utf8' is assumed, to unset it explicitly set it to `null`.
+#var encoding: String = "utf8"
+
+## (EXPERIMENTAL)
+## Whether to enable flow control handling (false by default). If enabled a message of `flow_control_pause`
+## will pause the socket and thus blocking the child program execution due to buffer back pressure.
+## A message of `flow_control_resume` will resume the socket into flow mode.
+## For performance reasons only a single message as a whole will match (no message part matching).
+## If flow control is enabled the `flow_control_pause` and `flow_control_resume` messages are not forwarded to
+## the underlying pseudoterminal.
+#var handle_flow_control: bool = false
+#
+## (EXPERIMENTAL)
+## The string that should pause the pty when `handle_flow_control` is true. Default is XOFF ("\u0013").
+#var flow_control_pause: String = FLOW_CONTROL_PAUSE
+#
+## (EXPERIMENTAL)
+## The string that should resume the pty when `handle_flow_control` is true. Default is XON ("\u0011").
+#var flow_control_resume: String = FLOW_CONTROL_RESUME
+
+#var _native_term # Platform appropriate instance of this class.
+var _pipe: Pipe
+
+
+func set_cols(value: int):
+	resize(value, rows)
+
+
+func set_rows(value: int):
+	resize(cols, value)
+
+
+func set_terminal_path(value := NodePath()):
+	terminal_path = value
+	set_terminal(get_node_or_null(terminal_path))
+
+
+func set_terminal(value: Terminal):
+	if terminal == value:
+		return
+
+	# Disconect the current terminal, if any.
+	if terminal:
+		disconnect("data_received", terminal, "write")
+		terminal.disconnect("data_sent", self, "write")
+		terminal.disconnect("size_changed", self, "resize")
+
+	terminal = value
+
+	if not terminal:
+		return
+
+	# Connect the new terminal.
+	# FIXME! resize(terminal.get_cols(), terminal.get_rows())
+	if not terminal.is_connected("size_changed", self, "resize"):
+		terminal.connect("size_changed", self, "resize")
+	if not terminal.is_connected("data_sent", self, "write"):
+		terminal.connect("data_sent", self, "write")
+	if not is_connected("data_received", terminal, "write"):
+		connect("data_received", terminal, "write")
+
+
+# Writes data to the socket.
+# data: The data to write.
+func write(data) -> void:
+	assert(data is String or data is PoolByteArray)
+
+	if data is PoolByteArray:
+		data = data.get_string_from_utf8()
+
+#	if handle_flow_control:
+#		# PAUSE/RESUME messages are not forwarded to the pty.
+#		if data == flow_control_pause:
+#			pause()
+#			return
+#		if data == flow_control_resume:
+#			resume()
+#			return
+#	# Everything else goes to the real pty.
+	_write(data)
+
+
+func _write(data: String) -> void:
+	if _pipe:
+		_pipe.write(data)
+
+
+# Resizes the dimensions of the pty.
+# cols: The number of columns.
+# rows: The number of rows.
+# Also accepts a single Vector2 argument where x is the the number of columns
+# and y is the number of rows.
+func resize(cols, rows = null) -> void:
+	assert(
+		(cols is Vector2 and rows == null) or (cols is int and rows is int),
+		"Usage: resize(size: Vector2) or resize(cols: int, rows: int)"
+	)
+
+	if cols is Vector2:
+		rows = cols.y  # Must get rows before reassigning cols!
+		cols = cols.x
+
+	if cols <= 0 or rows <= 0 or cols == NAN or rows == NAN or cols == INF or rows == INF:
+		push_error("Resizing must be done using positive cols and rows.")
+
+	_resize(cols, rows)
+
+
+func _resize(cols: int, rows: int) -> void:
+	assert(false, "Not implemented.")
+
+
+# Close, kill and destroy the pipe.
+func destroy() -> void:
+	pass
+
+
+# Kill the pty.
+# sigint: The signal to send. By default this is SIGHUP.
+# This is not supported on Windows.
+func kill(sigint: int = Signal.SIGHUP) -> void:
+	pass
+
+
+func fork(
+	p_file: String,
+	p_args = PoolStringArray(),
+	p_cwd: String = LibuvUtils.get_cwd(),
+	p_cols: int = DEFAULT_COLS,
+	p_rows: int = DEFAULT_ROWS
+):
+	push_error("Not implemented.")
+
+
+func open(cols: int = DEFAULT_COLS, rows: int = DEFAULT_ROWS) -> void:
+	pass
+
+
+func _parse_env(env: Dictionary = {}) -> PoolStringArray:
+	var keys := env.keys()
+	var pairs := PoolStringArray()
+
+	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.")
+
+		if not valid:
+			push_warning("Skipping invalid env key/value pair.")
+			continue
+
+		pairs.append("%s=%s" % [key, value])
+
+	return pairs
+
+
+func _process(_delta):
+	if _pipe:
+		_pipe.poll()
+
+
+func _notification(what: int):
+	match what:
+		NOTIFICATION_PARENTED:
+			var parent = get_parent()
+			if parent is Terminal:
+				set_terminal_path(get_path_to(parent))

addons/godot_xterm/nodes/pty/pty_icon.svg

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   id="svg4716"
+   version="1.1"
+   width="16"
+   viewBox="0 0 16 16"
+   height="16">
+  <metadata
+     id="metadata4722">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <defs
+     id="defs4720">
+    <clipPath
+       id="clipPath826"
+       clipPathUnits="userSpaceOnUse">
+      <use
+         height="100%"
+         width="100%"
+         id="use828"
+         xlink:href="#g822"
+         y="0"
+         x="0" />
+    </clipPath>
+  </defs>
+  <g
+     clip-path="url(#clipPath826)"
+     id="g824">
+    <g
+       id="g822">
+      <path
+         style="fill:#e0e0e0;fill-opacity:0.99607999"
+         d="M 4,1 1,5 H 3 V 8 H 5 V 5 h 2 z m 7,0 V 4 H 9 l 3,4 3,-4 H 13 V 1 Z m -2,9 v 1 h 1 v 4 h 1 v -4 h 1 v -1 z m -4,0 v 2 1 2 H 6 V 13 H 7 8 V 12 10 H 6 Z m 1,1 h 1 v 1 H 6 Z"
+         id="path4714" />
+    </g>
+  </g>
+</svg>

addons/godot_xterm/nodes/pty/pty_icon.svg.import

@@ -0,0 +1,34 @@
+[remap]
+
+importer="texture"
+type="StreamTexture"
+path="res://.import/pty_icon.svg-e9e42570b4744b3370a02d174395c793.stex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://addons/godot_xterm/nodes/pty/pty_icon.svg"
+dest_files=[ "res://.import/pty_icon.svg-e9e42570b4744b3370a02d174395c793.stex" ]
+
+[params]
+
+compress/mode=0
+compress/lossy_quality=0.7
+compress/hdr_mode=0
+compress/bptc_ldr=0
+compress/normal_map=0
+flags/repeat=0
+flags/filter=true
+flags/mipmaps=false
+flags/anisotropic=false
+flags/srgb=2
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/HDR_as_SRGB=false
+process/invert_color=false
+stream=false
+size_limit=0
+detect_3d=true
+svg/scale=1.0

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

@@ -0,0 +1,124 @@
+# Derived from https://github.com/microsoft/node-pty/blob/main/src/unixTerminal.ts
+# Copyright (c) 2012-2015, Christopher Jeffrey (MIT License).
+# Copyright (c) 2016, Daniel Imms (MIT License).
+# Copyright (c) 2018, Microsoft Corporation (MIT License).
+# Copyright (c) 2021, Leroy Hopson (MIT License).
+
+tool
+extends "../pty.gd"
+
+const PTYUnix = preload("./pty_unix.gdns")
+
+const FALLBACK_FILE = "sh"
+
+# Security warning: use this option with great caution, as opened file descriptors
+# with higher privileges might leak to the child program.
+var uid: int
+var gid: int
+
+var thread: Thread
+
+var _fd: int = -1
+var _exit_cb: FuncRef
+
+static func get_uid() -> int:
+	return -1  # Not implemented.
+
+static func get_gid() -> int:
+	return -1  # Not implemented.
+
+
+func _ready():
+	if autostart:
+		fork()
+
+
+func _resize(cols: int, rows: int) -> void:
+	if _fd < 0:
+		return
+
+	PTYUnix.new().resize(_fd, cols, rows)
+
+
+func _fork_thread(args):
+	var result = preload("./pty_unix.gdns").new().callv("fork", args)
+	print(result)
+	return result
+
+
+func fork(
+	file: String = OS.get_environment("SHELL"),
+	args: PoolStringArray = PoolStringArray(),
+	cwd = LibuvUtils.get_cwd(),
+	p_cols: int = DEFAULT_COLS,
+	p_rows: int = DEFAULT_ROWS,
+	uid: int = -1,
+	gid: int = -1,
+	utf8 = true
+):
+	# File.
+	if file.empty():
+		file = FALLBACK_FILE
+
+	# Environment variables.
+	# If we are using OS env vars, sanitize them to remove variables that might confuse our terminal.
+	var final_env := _sanitize_env(LibuvUtils.get_os_environ()) if use_os_env else {}
+	for key in env.keys():
+		final_env[key] = env[key]
+	var parsed_env: PoolStringArray = _parse_env(final_env)
+
+	# Exit callback.
+	_exit_cb = FuncRef.new()
+	_exit_cb.set_instance(self)
+	_exit_cb.function = "_on_exit"
+
+	# Actual fork.
+	var result = PTYUnix.new().fork(  # VERY IMPORTANT: The must be set null or 0, otherwise will get an ENOTSOCK error after connecting our pipe to the fd.
+		file, null, args, parsed_env, cwd, cols, rows, uid, gid, utf8, _exit_cb
+	)
+
+	if result[0] != OK:
+		push_error("Fork failed.")
+		status = STATUS_ERROR
+		return FAILED
+
+	_fd = result[1].fd
+	if _fd < 0:
+		push_error("File descriptor must be a non-negative integer value.")
+		status = STATUS_ERROR
+		return FAILED
+
+	_pipe = Pipe.new()
+	_pipe.open(_fd)
+
+	# Must connect to signal AFTER opening, otherwise we will get error ENOTSOCK.
+	_pipe.connect("data_received", self, "_on_pipe_data_received")
+
+	return OK
+
+
+func _on_pipe_data_received(data):
+	emit_signal("data_received", data)
+
+
+func _on_exit(exit_code: int, signum: int) -> void:
+	emit_signal("exited", exit_code, signum)
+
+
+func _sanitize_env(env: Dictionary) -> Dictionary:
+	# Make sure we didn't start our server from inside tmux.
+	env.erase("TMUX")
+	env.erase("TMUX_PANE")
+
+	# Make sure we didn't start our server from inside screen.
+	# http://web.mit.edu/gnu/doc/html/screen_20.html
+	env.erase("STY")
+	env.erase("WINDOW")
+
+	# Delete some variables that might confuse our terminal.
+	env.erase("WINDOWID")
+	env.erase("TERMCAP")
+	env.erase("COLUMNS")
+	env.erase("LINES")
+
+	return env

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

@@ -0,0 +1,7 @@
+[gd_resource type="NativeScript" load_steps=2 format=2]
+
+[ext_resource path="res://addons/godot_xterm/native/godotxtermnative.gdnlib" type="GDNativeLibrary" id=1]
+
+[resource]
+class_name = "PTYUnix"
+library = ExtResource( 1 )