fix: refuse to create entries inside a stream - #84
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Creating a stream or storage resolved its parent by name without checking that the parent is a storage. With a stream named `a`, creating `/A/child` hung the new entry off the stream's directory entry as its child, which strict validation (and other readers) reject. The parent must now be a storage; otherwise the call fails with InvalidInput. Found by a fuzz target that drives the write API.
Creates, overwrites and removes streams and storages under names taken from the fuzz input (including names that differ only in case), then reopens the result under strict validation and checks every entry and its content against a model of what should be there.
mdsteele
reviewed
Sep 8, 2026
| let cursor = Cursor::new(Vec::new()); | ||
| let mut comp = CompoundFile::create(cursor).unwrap(); | ||
| comp.create_stream("/a").unwrap().write_all(b"data").unwrap(); | ||
| let err = match comp.create_stream("/A/child") { |
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Could this just be let err = comp.create_stream("/A/child").unwrap_err();, similarly to below?
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Creating a stream or storage did not check that the parent is a storage. Names compare case-insensitively, so with a stream
ain the root,create_stream("/A/child")hung the new entry off the stream's directory entry as a child, which strict validation (and other readers) reject.create_stream,create_new_streamandcreate_storagenow fail withInvalidInputwhen the parent is a stream.Found by the new
fuzz_writetarget in the second commit, which drives the write API and reopens the result under strict validation; it runs clean with the fix.