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[Lzip-bug] Tarlz 0.12 released

From: Antonio Diaz Diaz
Subject: [Lzip-bug] Tarlz 0.12 released
Date: Sun, 24 Feb 2019 19:05:28 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i586; en-US; rv: Gecko/20110420 SeaMonkey/2.0.14

I am pleased to announce the release of tarlz 0.12.

Tarlz is a massively parallel (multi-threaded) combined implementation of the tar archiver and the lzip compressor. Tarlz creates, lists and extracts archives in a simplified posix pax format compressed with lzip, keeping the alignment between tar members and lzip members. This method adds an indexed lzip layer on top of the tar archive, making it possible to decode the archive safely in parallel. The resulting multimember tar.lz archive is fully backward compatible with standard tar tools like GNU tar, which treat it like any other tar.lz archive. Tarlz can append files to the end of such compressed archives.

Tarlz can create tar archives with five levels of compression granularity; per file, per block (default), per directory, appendable solid, and solid.

Of course, compressing each file (or each directory) individually can't achieve a compression ratio as high as compressing solidly the whole tar archive, but it has the following advantages:

   * The resulting multimember tar.lz archive can be decompressed in
     parallel, multiplying the decompression speed.

   * New members can be appended to the archive (by removing the EOF
     member) just like to an uncompressed tar archive.

   * It is a safe posix-style backup format. In case of corruption,
     tarlz can extract all the undamaged members from the tar.lz
     archive, skipping over the damaged members, just like the standard
     (uncompressed) tar. Moreover, the option '--keep-damaged' can be
     used to recover as much data as possible from each damaged member,
     and lziprecover can be used to recover some of the damaged members.

   * A multimember tar.lz archive is usually smaller than the
     corresponding solidly compressed tar.gz archive, except when
     individually compressing files smaller than about 32 KiB.

Note that the posix pax format has a serious flaw. The metadata stored in pax extended records are not protected by any kind of check sequence. Because of this, tarlz protects the extended records with a CRC in a way compatible with standard tar tools.

The homepage is at http://www.nongnu.org/lzip/tarlz.html

An online manual for tarlz can be found at http://www.nongnu.org/lzip/manual/tarlz_manual.html

The sources can be downloaded from

The sha256sum is:
a81381dc0290d4b039b70af0588a813118ec13595ded26de0ab7c275b0120917 tarlz-0.12.tar.lz

Changes in version 0.12:

* When dumping a character special file or a block special file, the devmajor and devminor fields were incorrectly filled with the values corresponding to the device containing the special file instead of the values corresponding to the special file itself.

* If when creating an archive tarlz can't find a user or group name in the database, it now saves just the numerical uid/gid instead of exiting with error status.

* When listing verbosely a character special file or a block special file, the devmajor and devminor values are now shown.

* The new option '-d, --diff', which reports differences between archive and file system, has been added.

* The new option '--ignore-ids', which tells '-d, --diff' to ignore differences in owner and group IDs, has been added. This option is useful when comparing an --anonymous archive.

* Listing of large seekable uncompressed archives is now much faster because tarlz now skips over member data instead of reading it.

Please send bug reports and suggestions to address@hidden

Antonio Diaz, tarlz author and maintainer.
Self-determination is a right, not a crime. Free Catalan political prisoners.
If you care about long-term archiving, please help me replace xz with lzip. See http://www.nongnu.org/lzip/lzip_benchmark.html#xz1
http://www.nongnu.org/lzip/manual/lzip_manual.html#Quality-assurance and
http://www.nongnu.org/lzip/xz_inadequate.html Thanks.

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