archive/zip: don't read data descriptor early #501
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Go 1.17 introduced an unnecessary change to when a zip's data descriptor is read for file entries, how it is parsed and how the crc32 field is used. Before Go 1.17, the data descriptor was read immediately after a file entry's content. This continuous read is a pattern existing applications have come to rely upon (for example, where reads at specific offsets might be translated to HTTP range requests). In Go 1.17, all data descriptors are immediately read upon opening the file. This results in scattered and non-continuous reads of the archive, and depending on the underlying reader, might have severe performance implications. In addition, an additional object is now initialized for each entry, but is mostly redundant. Previously, the crc32 field in the data descriptor would return an error if it did not match the central directory's entry. This check has seemingly been unintentionally removed. If the central directory crc32 is invalid and a data descriptor is present, no error is returned. This change reverts to the previous handling of data descriptors, before CL 312310. Fixes #48374 Fixes #49089 Change-Id: I5df2878c4fcc9e500064e7175f3ab9727c82f100 Reviewed-on: https://go-review.googlesource.com/c/go/+/357489 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Trust: Dmitri Shuralyov <dmitshur@golang.org>
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@saracen Why is the test removed? |
@klauspost This test was added along with the modified The test was removed, because like the modified |
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Great! Thanks! |
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I expect a release soon to include #503 before merging the zstd decoder changes. |
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This is a patch originally applied to stdlib's
archive/zip: https://go-review.googlesource.com/c/go/+/357489/Your own
compress/zipfork synced with stdlib after the problem was introduced, but before this commit, which reverted the change.