https://bugs.documentfoundation.org/show_bug.cgi?id=83108
Robinson Tryon (qubit) <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEEDINFO Ever confirmed|0 |1 --- Comment #9 from Robinson Tryon (qubit) <[email protected]> --- (In reply to João Paulo from comment #8) > Hi, I can confirm LibreOffice 4.4.1.2 has a ramdomness problem when > generating font names: AAAAAA+Arial, AAAAAB+Arial etc. > Okay, that "randomness" part has been confirmed, but... (In reply to hyper_ch from comment #0) > LO seems to have a lack of randomness for glyphs when exporting to PDF. > ... > ...So, when you send the two PDFs to Ghostcript's pdfwrite device, > it gets the Arial font, with the "P" in index 0 for the first PDF, then it > gets Arial for the second document - but it already has an instance of Arial > defined, so uses that. It gets a reference to index 0, which is already > occupied, and thus does not need populated. It sounds like LibreOffice is generating legal PDF output, but Ghostscript can't handle two separate PDFs that reuse indexes/identifiers. > Bear with me, I'm getting to why it's a LibreOffice problem :-) > > Now, Adobe document a mechanism to prevent that kind of clash, which is > that such font subsets should have a unique, random six letter prefix I'm confused about "unique" AND "random". "unique" suggests reproducibility, and "random" suggests the opposite. > added > to the name. The problem is that LibreOffice always use the same seed to > create these prefixes for each document. So, for example, the prefixes are > always of the pattern AAAAAA+Arial, AAAAAB+Arial..... so they are unique > within the *current* document but not sufficiently unique to give protection > from this kind of clash. A random 6-letter prefix only gives ~309 million possibilities. That's a pretty small space, and doesn't seem like it gives much "protection" for the millions of PDF documents that I assume are produced every day. What does Adobe/the specs say about resolving collisions? Status -> NEEDINFO -- You are receiving this mail because: You are the assignee for the bug.
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