Error: Custom([file_write,stderr]) on startup

dustinaux · June 18, 2015, 12:20am

I recently released a game on Steam with openFL and HaxeFlixel and some users are reporting a crash on startup with the error “Error: Custom([file_write,stderr])”

I’ve seen the error myself in the past during development but it was very sporadic and haven’t seen it for a few months at least, and can’t reproduce it. It happens on the windows target. Maybe mac too but haven’t heard any reports yet.

Bug reports:
http://steamcommunity.com/app/368610/discussions/0/615086038664047518/
http://steamcommunity.com/app/368610/discussions/0/594820656463990356/

One user emailed me and says it happens just sometimes. Others all the time. Most people that buy the game seem to have no issues but there’s maybe 1% that get this error and can’t play at all.

I’m at a complete loss with very little to go on and can’t reproduce it, so I was hoping someone here may know what this error is about?

Thanks

player_03 · June 18, 2015, 1:42am

I’ve seen similar errors myself, and I’ve been able to work them out based on context. Normally the error looks more like [file_open, C:\Example\Path\To\SomeFile.txt]. At first I thought it was a “this file is open in another program” error, but it’s more general than that. file_open is the name of the function that crashed, and SomeFile.txt was the file that it was trying to open.

So in your case, it’s the file_write function that’s crashing, and it’s crashing when it tries to write to stderr.

I don’t know what you could do about it, but hopefully this helps anyway.

dustinaux · June 18, 2015, 2:15am

Makes sense, and is also what I found in an old issue here:

FWIW the Custom([file_write,stderr]) is a message that appears when an exception is thrown and not caught. OpenFL then somehow tries to write that error to disk or something, but fails in the process and that dialog box appears. So, that means that any error that would throw an exception will give that same dialog box.

But unfortunately that still doesn’t help much, it still amounts to basically just “there was an error.”

I found one instance in openFL source of “stderr” at https://github.com/openfl/openfl/blob/1ea6f103a581f139821990470ba27a12884f1ab1/openfl/_legacy/Lib.hx
line 362, which seems where it likely comes from since there’s also a Sys.exit() immediately following.

player_03 · June 18, 2015, 2:43am

It’s not just OpenFL that you have to search. OpenFL depends on Lime, and both of those depend on Haxe itself.

Plus, searching for “stderr” isn’t enough. You need to find where the file_write function is called.

github.com

HaxeFoundation/haxe/blob/development/std/cpp/_std/sys/io/FileOutput.hx#L64


/*
* Copyright (C)2005-2018 Haxe Foundation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
package sys.io;
import sys.io.FileSeek;
import cpp.NativeFile;


@:coreApi
class FileOutput extends haxe.io.Output {


	private var __f : Dynamic;


	function new(f:Dynamic) : Void {
		__f = f;
	}


	public override function writeByte( c : Int ) : Void {
		try NativeFile.file_write_char(__f,c) catch( e : Dynamic ) throw haxe.io.Error.Custom(e);
	}


	public override function writeBytes( s : haxe.io.Bytes, p : Int, l : Int ) : Int {
		return try NativeFile.file_write(__f,s.getData(),p,l) catch( e : Dynamic ) throw haxe.io.Error.Custom(e);
	}


	public override function flush() : Void {
		NativeFile.file_flush(__f);
	}


	public override function close() : Void {
		super.close();
		NativeFile.file_close(__f);
	}


	public function seek( p : Int, pos : FileSeek ) : Void {
		NativeFile.file_seek(__f,p, pos == SeekBegin ? 0 : pos ==  SeekCur ? 1 : 2);
	}


	public function tell() : Int {
		return NativeFile.file_tell(__f);
	}


}

Working backwards from there, we find that file_open() is only called from writeBytes(), which in turn is called from write(), which… is indeed called from rethrow().

Maybe you should make a couple changes to rethrow():

try {
    Sys.stderr ().write (Bytes.ofString (message));
} catch(e:haxe.io.Error) {
    throw new haxe.io.Error.Custom (message));
}

Hopefully then you can at least get the real error message.

singmajesty · June 22, 2015, 9:17pm

This error occurs when trying to write a file, but it can’t – like trying to write to a file when the directory path has not been created. Could this be caused by using a SharedObject, or do you write a file somewhere in your code?

dustinaux · June 22, 2015, 10:47pm

The only file writing being done would be with a SharedObject but I’m not sure if that would be the reason. Some users have fixed it after updating some sound drivers it seems, and others have it happen sporadically with different results depending on what other programs they have running. Nobody’s seem to found something that fixes it or makes it fail 100% of the time it seems.