pkg/filesystem: Make the zeroes underlying a pool file changeable #200
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So a future commit can still access the package by its name
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This allows bonanza to have (mutable) files backed by others. Bonanza can use another FileReader to supply the data for all the "holes" in a pool file. Note that this requires some care to work correctly: If a file is truncated to shrink and later extended again, the HoleSource must track that and emit zeroes from offset of the smallest truncation.
Right now we leave the size of the file set to zero, even if it was created with a non-zero size. This causes the stats for these files to be incorrect.
This is also the name of the underlying type.
Instead of simply returning the max() of the hole offsets of the file and the hole source, we need to repeatedly check for holes in both places. Only when we reach an offset where both locations correspond to a hole, we may return.
Instead of writing null bytes, the write path must now also merge data coming from the HoleSource. Otherwise we unintentially overwrite data before/after the area to be written with null bytes.
I'd rather use mocking here, so that we ensure that we properly respect the HoleSource instead of filling in null bytes ourselves.
This was referenced Oct 28, 2025
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This allows bonanza to have (mutable) files backed by others. Bonanza
can use another FileReader to supply the data for all the "holes" in a
pool file.
Note that this requires some care to work correctly: If a file is
truncated to shrink and later extended again, the HoleSource must track
that and emit zeroes from offset of the smallest truncation.