> `GZIPInputStream` supports reading data from multiple concatenated GZIP data > streams since [JDK-4691425](https://bugs.openjdk.org/browse/JDK-4691425). In > order to do this, after a GZIP trailer frame is read, it attempts to read a > GZIP header frame and, if successful, proceeds onward to decompress the new > stream. If the attempt to decode a GZIP header frame fails, or happens to > trigger an `IOException`, it just ignores the trailing garbage and/or the > `IOException` and returns EOF. > > There are several issues with this: > > 1. The behaviors of (a) supporting concatenated streams and (b) ignoring > trailing garbage are not documented, much less precisely specified. > 2. Ignoring trailing garbage is dubious because it could easily hide errors > or other data corruption that an application would rather be notified about. > Moreover, the API claims that a `ZipException` will be thrown when corrupt > data is read, but obviously that doesn't happen in the trailing garbage > scenario (so N concatenated streams where the last one has a corrupted header > frame is indistinguishable from N-1 valid streams). > 3. There's no way to create a `GZIPInputStream` that does _not_ support > stream concatenation. > > On the other hand, `GZIPInputStream` is an old class with lots of existing > usage, so it's important to preserve the existing behavior, warts and all > (note: my the definition of "existing behavior" here includes the bug fix in > [JDK-7036144](https://bugs.openjdk.org/browse/JDK-7036144)). > > So this patch adds a new constructor that takes two new parameters > `allowConcatenation` and `allowTrailingGarbage`. The legacy behavior is > enabled by setting both to true; otherwise, they do what they sound like. In > particular, when `allowTrailingGarbage` is false, then the underlying input > must contain exactly one (if `allowConcatenation` is false) or exactly N (if > `allowConcatenation` is true) concatenated GZIP data streams, otherwise an > exception is guaranteed.
Archie Cobbs has updated the pull request incrementally with one additional commit since the last revision: Revert all functional changes, leaving only tests & Javadoc. ------------- Changes: - all: https://git.openjdk.org/jdk/pull/18385/files - new: https://git.openjdk.org/jdk/pull/18385/files/f3939c05..a69bf2a9 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=18385&range=08 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18385&range=07-08 Stats: 133 lines in 3 files changed: 18 ins; 84 del; 31 mod Patch: https://git.openjdk.org/jdk/pull/18385.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/18385/head:pull/18385 PR: https://git.openjdk.org/jdk/pull/18385
