RFR: 8313739: ZipOutputStream.close() should always close the wrapped stream [v3]

[Eirik Bjørsnøs]

On Tue, 2 Jan 2024 12:21:21 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

>> Please consider this PR which makes `DeflaterOutputStream.close()` always close its wrapped output stream exactly once.
>> 
>> Currently, closing of the wrapped output stream happens outside the finally block where `finish()` is called. If `finish()` throws, this means the wrapped stream will not be closed. This can potentially lead to leaking resources such as file descriptors or sockets.
>> 
>> This fix is to move the closing of the wrapped stream inside the finally block.
>> 
>> Additionally, the `closed = true;` statement is moved to the start of the close method. This makes sure we only ever close the wrapped stream once (this aligns with the overridden method `FilterOutputStream.close´)
>> 
>> Specification: This change brings the implementation of `DeflaterOutputStream.close()` in line with its specification:  *Writes remaining compressed data to the output stream and closes the underlying stream.*
>> 
>> Risk: This is a behavioural change. There is a small risk that existing code depends on the close method not following its specification.
>> 
>> Testing: The PR adds a new JUnit 5 test `CloseWrappedStream.java` which simulates the failure condition and verifies that the wrapped stream was closed under failing and non-failing conditions.
>
> Eirik Bjørsnøs has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Add more extensive testing of combined write/close failure modes
>  - Don't suppress if finishException is null, mark stream as closed even when closing the wrapped stream failed

A CSR for this change has been proposed and is ready for review: [JDK-8322871](https://bugs.openjdk.org/browse/JDK-8322871)

-------------

PR Comment: https://git.openjdk.org/jdk/pull/17209#issuecomment-1874623292