Implement pipe API for executed processes IO redirection.

[bruvzg]

• Implement OS.execute_with_pipe method to run process with redirected stdio.
  • Allow reading process output incrementally (from a thread, since pipes are blocking).
  • Allow independently reading stdout and stderr.
  • Allow writing to process stdin.
  • IO use FileAccess API, instead of limiting it to the String.
• Implement pipe://* path handling for creation of named pipes.
  • Mostly side product of the API, but can be useful for something.

Implemented on Windows and Unix (tested on macOS, but should work on Linux/Android as well).

Samples - click to expand

Process redirect:

var pipe
var thread


func _ready():
	# start terminal and open pipes
	var info
	if OS.get_name() == "Windows":
		info = OS.execute_with_pipe("cmd.exe", [])
	else:
		info = OS.execute_with_pipe("/bin/zsh", [])
	pipe = ret["stdio"]
	print(ret)
	thread = Thread.new()
	thread.start(_thread_func)
	get_window().close_requested.connect(clean_func)


func _thread_func():
	# read stdin and add to TextEdit.
	while pipe.is_open() and pipe.get_error() == OK:
		_add_char.call_deferred(char(pipe.get_8()))


func _add_char(c):
	$TextEdit.text += c
	$TextEdit.scroll_vertical = $TextEdit.get_v_scroll_bar().max_value


func _on_line_edit_text_submitted(new_text: String) -> void:
	# send command to stdin.
	var cmd = new_text + "\n"
	var buffer = cmd.to_utf8_buffer()
	pipe.store_buffer(buffer)
	$LineEdit.text = ""


func clean_func():
	# close pipe and cleanup.
	pipe.close()
	thread.wait_to_finish()

Named pipe (server):

	var pipe_nw = FileAccess.open("pipe://test_pipe_3425r72347hjkv", FileAccess.WRITE)
	pipe_nw.store_64(234334); # depending on platform, might block until client connected

Named pipe (client):

	var pipe_nr = FileAccess.open("pipe://test_pipe_3425r72347hjkv", FileAccess.READ)
	var r = pipe_nr.get_64();
	print(r)

• Production edit: See Improve OS.execute() (run a callback with the line contents every time a line is printed) godot-proposals#216.

[KoBeWi]

Tested on Windows and it works great.

[akien-mga]

Thanks!

[KoBeWi]

Unless I'm missing something, there is no way to get the result code from finished process 🤔

[silverkorn]

Unless I'm missing something, there is no way to get the result code from finished process 🤔

Maybe check tiny-process-library techniques?

• https://gitlab.com/eidheim/tiny-process-library/-/blob/master/process_win.cpp
• https://gitlab.com/eidheim/tiny-process-library/-/blob/master/process_unix.cpp

[time-killer-games]

Thank you so very much for this! Life saver!!! :D

[wyattbiker]

PLEASE IGNORE THIS COMMENT. I TESTED AGAIN (NO UPDATES NOR CHANGES) AND FOR WHATEVER REASON, IT"S WORKING. I''LEAVE COMMENT IN CASE IT COMES BACK. THANKS

Hi I am testing on Linux : Kubuntu 23.10, KDE Plasma Version: 5.27.8

Using the samples, I can get the named pipes to work. However I cannot get the Process Redirect to work.
(Also in the sample array ret["stdio"] should be info["stdio"])

I changed the execute command to /usr/bin/bash -c uname for Linux. It does transfer the output to TextEdit when I run it. However when I type something in LineEdit and press Enter, the _on_line_edit_text_submitted(new_text: String) executes, but then the application just terminates does not even go to clean_func. No message. Any ideas?

Here is the code I run:

extends Control

var pipe
var thread

func _ready():
	$TextEdit.text = "Textedit "
	$LineEdit.text = "Lineedit "
	# start terminal and open pipes
	var info
	if OS.get_name() == "Windows":
		info = OS.execute_with_pipe("cmd.exe", [])
	else:
		var args = ["-c","uname"]
		info = OS.execute_with_pipe("/usr/bin/bash", args)
		pass
	pipe = info["stdio"]
	print(info)
	thread = Thread.new()
	thread.start(_thread_func)
	get_window().close_requested.connect(clean_func)

func _thread_func():
	# read stdin and add to TextEdit.
	while pipe.is_open() and pipe.get_error() == OK:
		_add_char.call_deferred(char(pipe.get_8()))

func _add_char(c):
	print(c)
	$TextEdit.text += c
	$TextEdit.scroll_vertical = $TextEdit.get_v_scroll_bar().max_value

func _on_line_edit_text_submitted(new_text: String) -> void:
	# send command to stdin.
	var cmd = new_text + "\n"
	var buffer = cmd.to_utf8_buffer()
	pipe.store_buffer(buffer)
	$LineEdit.text = ""

func clean_func():
	# close pipe and cleanup.
	pipe.close()
	thread.wait_to_finish()

[wyattbiker]

PLEASE IGNORE THIS COMMENT. I TESTED AGAIN (NO UPDATES NOR CHANGES) AND FOR WHATEVER REASON, IT"S WORKING. I''LEAVE COMMENT IN CASE IT COMES BACK. THANKS

Additional Info:

I get this error in the output when it hits a breakpoint right after `info = OS.execute_with_pipe("/usr/bin/bash", args)

Godot Engine v4.3.beta1.official.a4f2ea91a - https://godotengine.org
Vulkan 1.3.255 - Forward+ - Using Device #0: Intel - Intel(R) Graphics (ADL GT2)

  editor/editor_properties.cpp:1328 - Cannot reliably represent '-9223372004306975481' in the inspector, value is too large.
  editor/editor_properties.cpp:1328 - Cannot reliably represent '-9223372004290198016' in the inspector, value is too large.
  editor/editor_properties.cpp:1328 - Cannot reliably represent '-9223372004306975481' in the inspector, value is too large.
  editor/editor_properties.cpp:1328 - Cannot reliably represent '-9223372004290198016' in the inspector, value is too large.

Also info is { "stdio": <FileAccess#-9223372004306975481>, "stderr": <FileAccess#-9223372004290198016>, "pid": 3668695 }