CFF2 fonts with no vstore are rejected

[plokmijnuhby]

If a font using CFF2 has no variation data, according to the OTF spec, it should not reference a vstore in its top DICT. However, if it doesn't reference a vstore, OTS will reject it, with the message "Failed to parse Top DICT Data".
This happens because the code to check the top DICT (here) assumes that a vstore is present, reads the entire dict looking for it, gets to the end of the dict and can't read any more bytes, and complains.

[jfkthame]

@plokmijnuhby Could you attach an example of such a font (or point to a freely-available one)? I'd be reluctant to try fixing without a testcase on hand.

[plokmijnuhby]

I don't have a fully complete file available unfortunately (and I couldn't find one online). This file has no vstore and triggers the message, although it has other issues which are nothing to do with this bug.
font.zip

[behdad]

We should fix this. I don't immediately see where the error comes from. Can you please paste the error output at least? A test font would be best.

[plokmijnuhby]

The only errors are these:

[behdad]

I don't have a fully complete file available unfortunately (and I couldn't find one online). This file has no vstore and triggers the message, although it has other issues which are nothing to do with this bug.

When I debug the failure with this font, it's using operator byte 11 in TopDICT. There's no such operation in the CFF2 spec, so OTS fails.