Lbzip2

This release fixes a use-after-free security vulnerability introduced in version 2.0. All users are recommended to update to version 2.1.

In this release, lbzip2 writes a single compressed stream per bz2 file instead of multiple concatenated streams. It doesn't decompress streams embedded within trailing garbage. It detects and rejects more kinds of invalid bz2 files. Relying on the independent bzip2 stack written by the new maintainer, lbzip2-2.0 features significantly improved (de)compression speed and robustness. In verbose mode, the compression ratio and progress information is displayed for each file. Decompression failures result in more detailed messages now. Lbzip2-2.x is licensed under the GPL v3.0 or any later version.

In this release, if lbzip2 intends to exit with status 1 due to any fatal error, but any SIGPIPE or SIGXFSZ with an inherited SIG_DFL action was generated for lbzip2 previously, then lbzip2 terminates by way of one of the said signals, after cleaning up any interrupted output file. This should improve compatibility with GNU tar when it spawns lbzip2 as a filter and closes the pipe between them early, before it receives an EOF from lbzip2.

Code examination revealed that lbzip2-0.18 introduced a race between the following two code paths: the muxer thread displays an error message when it encounters a write error; and the main thread, in preparation to terminate the process, frees the output file name after an INT or TERM signal is delivered to it. This bug had a negligible chance to occur, but it was fixed nonetheless.

This release cleans up two theoretical portability problems. The input file's sanity check in the multiple-workers decompressor relied on character constants being encoded in ASCII; such character constants were replaced by their ASCII octet values. "Flexible" array members were replaced by unnamed memory regions following the affected structures, since the "struct hack" idiom entails undefined behavior in C89.