Summary

If the underlying OutputStream associated with ZipOutputStream or GZIPOutputStream throws an IOException while the zip stream is being closed, the associated compressor is left in an inconsistent state and may cause infinite looping.

Problem

If a call to GZIPOutputStream.close(), GZIPOutputStream.finish() or ZipOutputStream.closeEntry() results in an IOException, an call to GZIPOutputStream.write() or ZipOutputStream.write() may result in an infinite loop.

Solution

If an IOException is encountered while using the default JDK compressor in GZIPOutputStream.finish() or ZipOutputStream.closeEntry(), then close the compressor before propagating that Exception up the stack. DeflaterOutputStream.close() is hardened to ensure that the default JDK compressor is closed in case where Throwable is propagated up the stack. This will ensure that subsequent write operations using the same deflater will fail. An exception is made for the ZipOutputStream.closeEntry() call. For that method, IOExceptions of type ZipException will not cause the associated compressor to be closed.

Harden DeflaterOutputStream.close() to close out the associated default JDK compressor before propagating a Throwable (if any) up the stack

Harden ZIPOutputStream.closeEntry() to close out the associated default JDK compressor before propagating an IOException, not of type ZipException, (if any) up the stack

Harden GZIPOutputStream.finish() to close out the associated default JDK compressor before propagating an IOException (if any) up the stack

The behavioral change will be documented in a release note.

Specification

A future CSR may propose spec clarifications.