Silent woff2_decompress failure?

[justvanrossum]

I'm having a very large font (that I cannot share publicly), that successfully compresses with woff2_compress:

Processing /path/to/my/font.ttf => /path/to/my/font.woff2
Compressed 45975079 to 21308821.

If I decompress it with fonttools, the result is fine (identical except for the head table, the mod date differs probably).

But woff2_decompress doesn't produce any output, and no error message is shown. The exit code is 1, though.

opentype-sanitizer is complaining about this file, too:

$ python -m ots /path/to/my/font.woff2 
ERROR: Failed to convert WOFF 2.0 font to SFNT
Failed to sanitize file!

Perhaps it is the same issue, as it appears that ots uses google/woff2.

If anyone would be willing to have a look, I'd gladly share the file privately. It's from the GS CJK project, in case you're familiar with that.

[justvanrossum]

Hm, maybe this is a clue: if I try to use the uncompressed font in a web page, Chrome complains:

OTS parsing error: Web font size more than 30MB

If I try to use the woff2 file, Chrome echoes ots:

OTS parsing error: Failed to convert WOFF 2.0 font to SFNT

For completeness sake: ots does not complain about the uncomressed ttf outside of Chrome.

[jfkthame]

I believe Chrome configures a smaller size limit for OTS than the default that you presumably get if you build it standalone; see khaledhosny/ots#244.

[drott]

Is this identical to https://bugs.chromium.org/p/chromium/issues/detail?id=1348101 ?

[justvanrossum]

(I have no access to that issue, so I wouldn't know)

[anthrotype]

it reads like this:

Issue 1348101: 30MB OTS Limit too small for certain fonts
Reported by drott@chromium.org on Thu, Jul 28, 2022, 8:00 AM GMT+1 (28 days ago)
The 30MB limit by OTS to accept web fonts after decoding is too small for certain fonts. For example the internal Google Sans CJK.
Let's consider raising it.

[justvanrossum]

It's definitely related. My main issue here is probably two things:

• it hardcodes a limit that may not apply to all users of the tool
• when it hits the limit, it doesn't tell you that it does, it just fails with a non-zero exit code

[anthrotype]

this:

woff2/include/woff2/output.h

Lines 19 to 20 in 4721483

	// Suggested max size for output.
	const size_t kDefaultMaxSize = 30 * 1024 * 1024;