LibGfx/JBIG2: Fix cross-chunk segment refs in embedded organization#26199
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nico merged 1 commit intoSerenityOS:masterfrom Sep 10, 2025
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LibGfx/JBIG2: Fix cross-chunk segment refs in embedded organization#26199nico merged 1 commit intoSerenityOS:masterfrom
nico merged 1 commit intoSerenityOS:masterfrom
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The extra validation in SerenityOS#26191 was added at the end of decode_segment_headers(). But in decode_embedded(), that can be called several times, once for each data chunk. We want to decode segment headers from all chunks first before we do validation, so that segments in later chunks can refer to segments in earlier chunks. Add a new complete_decoding_all_segment_headers() to house the validation code, and call it after all segment chunks have been decoded. Unbreaks rendering 0000372.pdf page 11 and 0000857.pdf pages 1-4.
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Test case created by copying Tests/LibGfx/test-inputs/jbig2/bitmap-symbol.jbig2, changing the byte at offset 0x31 from 0x01 to 0x00 to make the symbol dictionary segment a global segment instead of associated with page 1, then ran Meta/jbig2_to_pdf.py on that modified file to create the new PDF. The new file contains a JBIG2Globals stream with the symbol dictionary segment, which the main jbig2 data stream refers to. This would've caught the regression fixed in SerenityOS#26199.
nico
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Test case created by copying Tests/LibGfx/test-inputs/jbig2/bitmap-symbol.jbig2, changing the byte at offset 0x31 from 0x01 to 0x00 to make the symbol dictionary segment a global segment instead of associated with page 1, then ran Meta/jbig2_to_pdf.py on that modified file to create the new PDF. The new file contains a JBIG2Globals stream with the symbol dictionary segment, which the main jbig2 data stream refers to. This would've caught the regression fixed in SerenityOS#26199.
nico
added a commit
that referenced
this pull request
Sep 10, 2025
Test case created by copying Tests/LibGfx/test-inputs/jbig2/bitmap-symbol.jbig2, changing the byte at offset 0x31 from 0x01 to 0x00 to make the symbol dictionary segment a global segment instead of associated with page 1, then ran Meta/jbig2_to_pdf.py on that modified file to create the new PDF. The new file contains a JBIG2Globals stream with the symbol dictionary segment, which the main jbig2 data stream refers to. This would've caught the regression fixed in #26199.
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The extra validation in #26191 was added at the end of decode_segment_headers(). But in decode_embedded(), that can be called several times, once for each data chunk.
We want to decode segment headers from all chunks first before we do validation, so that segments in later chunks can refer to segments in earlier chunks.
Add a new complete_decoding_all_segment_headers() to house the validation code, and call it after all segment chunks have been decoded.
Unbreaks rendering 0000372.pdf page 11 and 0000857.pdf pages 1-4.