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Write a full save's cross-reference table as one subsection - #86
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A full save wrote a subsection per run of written objects and gave the numbers between runs no entry at all. Every engine editing session holds object numbers it may never use, so a rewrite after any edit left holes (64 per local session) under /Size. ISO 32000-1 7.5.4 says a file that was never updated has one subsection, numbered from 0, and Acrobat can't judge a later revision against a table with holes: a signature over a rewritten file read as indeterminate after any edit (HasSparseXref). - complete-xref: the table is one subsection from 0 through the last number written. A number no written object holds is a free entry with generation 0; entry 0 heads the free list, each entry links to the next higher one, and the last links back to 0. Object numbers never change. Update sections (incremental saves) are unchanged. - check_saved_pdfs.py: a full rewrite's table must be one subsection from 0 through /Size. - FPDFSaveEmbedderTest.SaveLinearizedDoc: 26 and 28 are free entries now (+28 bytes).
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A full save wrote a subsection per run of written objects and gave the numbers between runs no entry at all. Every engine editing session holds object numbers it may never use, so a rewrite after any edit left holes (64 per local session) under /Size. ISO 32000-1 7.5.4 says a file that was never updated has one subsection, numbered from 0, and Acrobat can't judge a later revision against a table with holes: a signature over a rewritten file read as indeterminate after any edit (HasSparseXref).