[js] blit may throw "source too large" exception if length is changed

[vroad]

On js, specifying length in constructor is not allowed, but subclasses of haxe.io.Bytes could set this to a different value. OpenFL ByteArray sometimes stops working with this exception on js. Probably blit() should use src.b.byteLength (or src.b.length?) to get consistent behavior in this case.

[ncannasse]

I tried reading several times but still couldn't get it: could you post some actual code?

Also, your issue title is way too long :-)

[vroad]

I'll try creating some test code.

[vroad]

I tried creating test code from OpenFL ByteArray impl. This throws "Source too large" error only on js, but not on other targets such as cpp because b.byteLength and length no longer match in Bytes.

import haxe.io.Bytes;
import haxe.io.BytesData;

class ExtBytes extends Bytes {

    private var __length:Int;

    public function new(length:Int)
    {
        var bytes:Bytes = Bytes.alloc (length);
        #if js
        super(bytes.b.buffer);
        #else
        super(length, bytes.b);
        #end
        __length = length;
    }

    public function clear ():Void {

        length = 0;

    }

    public function __resize (size:Int) {

        if (size > __length) {

            var bytes = Bytes.alloc ((((size + 1) * 3) >> 1));
            var cacheLength = length;
            length = __length;
            bytes.blit (0, this, 0, __length);
            length = cacheLength;
            __setData (bytes);

        }

        if (length < size) {

            length = size;

        }

    }

    private inline function __setData (bytes:Bytes):Void {

        b = bytes.b;
        __length = bytes.length;

        #if js
        data = bytes.data;
        #end

    }
}

class Test {
    static function main() {
        var src:ExtBytes = new ExtBytes(50);
        src.clear();
        src.__resize(25);
        var dst:ExtBytes = new ExtBytes(20);
        dst.clear();
        dst.__resize(25);
        dst.blit(0, src, 0, 25);
    }
}

http://try.haxe.org/#F94C9

[vroad]

I fixed this by checking underlying Uint8Array's byteLength instead of Bytes.length. Should I make pull request instead?

vroad@4eddb4d

[tbilou]

We're having the same issue.
Tried the "fix" locally and it solved the problem.
@ncannasse how should we proceed here? pull request?

[ncannasse]

@tbilou yes a PR would work, thanks

[tbilou]

@vroad can you create the pull request?

[vroad]

@tbilou Created a PR. #5499

[ncannasse]

Closed by 8c03ac1