lzip/tarlz
1
0
Fork 0
Code Issues Activity

Merging upstream version 0.11.

Browse source 
Signed-off-by: Daniel Baumann <daniel@debian.org>
This commit is contained in:
Daniel Baumann 2025-02-17 21:12:14 +01:00
parent 3b818501c2
commit 5db1949a73
Signed by: daniel
GPG key ID: FBB4F0E80A80222F
18 changed files with 1504 additions and 654 deletions
Download patch file Download diff file Expand all files Collapse all files

39
README
View file

@ -1,21 +1,21 @@
Description
Tarlz is a combined implementation of the tar archiver and the lzip
compressor. By default tarlz creates, lists and extracts archives in a
simplified posix pax format compressed with lzip on a per file basis. Each
tar member is compressed in its own lzip member, as well as the end-of-file
blocks. 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 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 four levels of compression granularity;
per file, per directory, appendable solid, and solid.
Tarlz can create tar archives with five levels of compression granularity;
per file, per block, per directory, appendable solid, and solid.
Of course, compressing each file (or each directory) individually is
less efficient than compressing the whole tar archive, but it has the
following advantages:
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.
@ -48,14 +48,15 @@ potentially much worse that undetected corruption in the data. Even more so
in the case of pax because the amount of metadata it stores is potentially
large, making undetected corruption more probable.
Because of the above, tarlz protects the extended records with a CRC in
a way compatible with standard tar tools.
Because of the above, tarlz protects the extended records with a CRC in a
way compatible with standard tar tools.
Tarlz does not understand other tar formats like gnu, oldgnu, star or v7.
The diagram below shows the correspondence between each tar member
(formed by one or two headers plus optional data) in the tar archive and
each lzip member in the resulting multimember tar.lz archive:
The diagram below shows the correspondence between each tar member (formed
by one or two headers plus optional data) in the tar archive and each lzip
member in the resulting multimember tar.lz archive, when per file
compression is used:
tar
+========+======+=================+===============+========+======+========+