Jpx infinite loop for tiles with 0 Psot

JPEG2000 allows to set tile-part length to 0 in SOT segment (only the last part). This case is not handled in the code resulting in an infinite loop. End of data stream is marked by EOC in this case. As padding is possible, it must be found. Below possible solution:

tile.length = readUint32(data, position + 4);
if (tile.length === 0) {
  for (var i = end - 2; i > position + length; i--) {
    if (0xFFD9 === readUint16(data, i)) {
      tile.dataEnd = i;
      break;
    }
  }
  if (tile.dataEnd === undefined) {
    throw new Error('JPX Error: missing EOC');
  }
} else {
  tile.dataEnd = tile.length + position - 2;
}

[Snuffleupagus]

@timvandermeij Sorry, but I think the right label would be 4-image-jpx here.

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Also, the document in https://github.com/mozilla/pdf.js/issues/10793#issuecomment-490522099 doesn’t contain a single JPX image, actually it doesn’t even contain any XObject of any kind. Hence that comment is completely unrelated to this issue, and only serves to add confusion to the discussion. (It seems related to a custom implementation, since the file renders fine in the default viewer.)

@timvandermeij Mind hiding/removing https://github.com/mozilla/pdf.js/issues/10793#issuecomment-490522099 and also this comment itself; thank you!

[madej]

On the other hand solution is right there, just review it and add it to codebase.

As purely a matter of principle, we don’t want to make these types of code changes without any way of either verifying or testing them since doing so has the potential to cause regressions elsewhere.

If you look closer, it’s just an ‘if’ statement for this special case, ‘else’ doesn’t change anything

Creating j2k file seems quite easy with hex editor.

If it’s indeed easy, then please just provide a PDF file that can be used to reproduce this 😃

I said j2k.

Without more information, I’d still suggest closing this issue as INCOMPLETE for now.

It’s closed by now. 👍