[PDFBOX-5191] isEmbeddingPermitted() is too restrictive on TTFs with OS2 table versions 0-2

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.21, 3.0.0 PDFBox
• Fix Version/s: 2.0.24, 3.0.0 PDFBox
• Component/s: PDModel
• Assignee: Tilman Hausherr
• Reporter: Larry Lynn
• Created: 11/May/21 16:48
• Updated: 11/Jun/21 06:08
• Resolved: 14/May/21 07:33

Description

PDFBOX-4882 fixed a bug that made isEmbeddingPermitted() too permissive.  But it introduced a bug that made isEmbeddingPermitted() too restrictive for TTFs with OS2 table versions 0-2.

 

TTFs with OS2 table versions 0-2 can have multiple permission bits set.  According to the spec described in 

https://docs.microsoft.com/en-us/typography/opentype/spec/os2#fstype

"in the event that more than one of bits 0 to 3 are set in a given font, then the least-restrictive permission indicated take precedence."

Unfortunately, the current code essentially makes the most restrictive permission take precedence.  This causes pdfbox to throw an error: 

"This font does not permit embedding"

when attempting to process fonts that worked fine in pdfbox v2.0.20 and lower

Issue Links

• is caused by: PDFBOX-4882 Two conditions are always false in TrueTypeEmbedder.isEmbeddingPermitted
• links to: download link to a TTF file that reproduces the permissions problem.
• links to: GitHub Pull Request #117
• links to: PR with a proposed patch to address this bug
• links to: TTF OS2 fsType documentation