* Decode bzip2 pages in BitRock installers - #400
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InstallBuilder content reconstruction rejects cookfs pages with compression id 2 even though the embedded Cookfs format supports bz2 pages. Decode each page with the managed BZip2 stream and cover it with a multi-page byte-exact fixture. Creation is still unavailable because a valid installer requires the vendor runtime stub.
… bzip2 stream A CFS0002 bzip2 page is [u32 BE uncompressed size][bzip2 stream], but the reader handed the whole page to the bzip2 decoder, so a real page fails on its first four bytes. The fixture was built to the same wrong layout, which is why the round-trip test passed. Layout taken from the BSD-licensed cookfs 1.4 sources (CookfsReadPageBz2 / CookfsWritePageBz2, rung 1 as specification; no code copied). The reader now skips and checks the prefix: a page too short for it, or one whose stream decodes to a different length, is rejected. Fixtures follow the cookfs layout; the notes no longer claim bzip2 InstallBuilder samples were seen.
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What changed
BitRock's cookfs (CFS0002) content reader handled stored and raw-DEFLATE pages and rejected compression id 2. This adds bzip2 pages.
In a CFS0002 bzip2 page the uncompressed size comes first, as a big-endian u32, followed by the bzip2 stream: libbz2's buffer API needs the output size, and the CFS0002 index doesn't record it. The first revision of this PR decoded from byte 0 and built its fixture the same way, so the test passed while real pages would fail. The reader now skips the prefix and checks it. A page too short for the prefix, or one that decodes to a different length, is rejected.
Sourcing
Rung 1 used as a specification: the BSD-licensed cookfs 1.x sources (
generic/pagesCompr.c,CookfsReadPageBz2/CookfsWritePageBz2, tag v1.4.0 of github.com/chpock/cookfs). No code was copied. Decoding uses the repository's managed BZip2 stream.Verification
dotnet test --filter Compression.Tests.BitRock: 15 passed.FORMAT-NOTES.mdsays so.BitRock stays read-only.