Bugfix and optimize GetStartXrefPosition#1036
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BobLd merged 2 commits intoUglyToad:masterfrom May 13, 2025
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The bugfix was the important part but the optimization is pretty nice too. - Bugfix: If startxref was found so far back (eg in the very beginning which can be the case for Linearized PDFs) that we ended up setting actualStartOffset to 0 then the loop would exit immediately without actually searching that part. - Optimization: GetStartXrefPosition would search for startxref in the last 2048 bytes and then double that search-range (looking back 4096, 8192, etc bytes) to look for startxref until the entire file was searched. This was rather inefficient since each step would search the same parts over and over again. This has been changed to properly search (still increasingly larger) chunks that doesn't overlap. On a test of 5000 PDFs that reduced their load-time by 10%. - Change: No need for the exception to say that startxref couldn't be found "in the last 2048 characters" since the entire file was searched anyway.
BobLd
approved these changes
May 13, 2025
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Wonderful, thanks @BobLd 👍 |
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@ricflams if you have document samples that where failing before your fix, feel free to share them here, im happy to add tests. Or feel free to add a PR with tests |
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@BobLd, here's one example of a file with some trailing html that's would cause the former backwards-search to fail finding the startxref - it would wrongfully skip searching the first about 50K of the file. |
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The bugfix was the important part but the optimization is pretty nice too.