[PDFBOX-5326] TTFSubsetter incorrectly calculating 'searchRange'

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.24
• Fix Version/s: 2.0.25, 3.0.0 PDFBox
• Component/s: FontBox
• Assignee: Tilman Hausherr
• Reporter: Brian Blocher
• Created: 18/Nov/21 18:43
• Updated: 17/Dec/21 06:50
• Resolved: 19/Nov/21 19:42

Description

The log2 method in TTFSubsetter is incorrectly calling round instead of floor on the log2 result.

If 

Math.log(num) / Math.log(2)

results in a whole number, the searchRange is correct but decimal results could get rounded up or down. 

The spec calls for a floor of the result.
https://docs.microsoft.com/en-us/typography/opentype/spec/cmap#:~:text=uint16-,searchRange,-Maximum%20power%20of

Attached two svgs with embedded subset fonts. Firefox gives the best console error output.