Adding upstream version 1.23.upstream/1.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+Description
+
+Lziprecover is a data recovery tool and decompressor for files in the lzip
+compressed data format (.lz). Lziprecover is able to repair slightly damaged
+files (up to one single-byte error per member), produce a correct file by
+merging the good parts of two or more damaged copies, reproduce a missing
+(zeroed) sector using a reference file, extract data from damaged files,
+decompress files, and test integrity of files.
+
+Lziprecover can remove the damaged members from multimember files, for
+example multimember tar.lz archives.
+
+Lziprecover provides random access to the data in multimember files; it only
+decompresses the members containing the desired data.
+
+Lziprecover facilitates the management of metadata stored as trailing data
+in lzip files.
+
+Lziprecover is not a replacement for regular backups, but a last line of
+defense for the case where the backups are also damaged.
+
+The lzip file format is designed for data sharing and long-term archiving,
+taking into account both data integrity and decoder availability:
+
+   * The lzip format provides very safe integrity checking and some data
+     recovery means. The program lziprecover can repair bit flip errors
+     (one of the most common forms of data corruption) in lzip files, and
+     provides data recovery capabilities, including error-checked merging
+     of damaged copies of a file.
+
+   * The lzip format is as simple as possible (but not simpler). The lzip
+     manual provides the source code of a simple decompressor along with a
+     detailed explanation of how it works, so that with the only help of the
+     lzip manual it would be possible for a digital archaeologist to extract
+     the data from a lzip file long after quantum computers eventually
+     render LZMA obsolete.
+
+   * Additionally the lzip reference implementation is copylefted, which
+     guarantees that it will remain free forever.
+
+A nice feature of the lzip format is that a corrupt byte is easier to repair
+the nearer it is from the beginning of the file. Therefore, with the help of
+lziprecover, losing an entire archive just because of a corrupt byte near
+the beginning is a thing of the past.
+
+Compression may be good for long-term archiving. For compressible data,
+multiple compressed copies may provide redundancy in a more useful form and
+may have a better chance of surviving intact than one uncompressed copy
+using the same amount of storage space. This is specially true if the format
+provides recovery capabilities like those of lziprecover, which is able to
+find and combine the good parts of several damaged copies.
+
+Lziprecover is able to recover or decompress files produced by any of the
+compressors in the lzip family: lzip, plzip, minilzip/lzlib, clzip, and
+pdlzip.
+
+If the cause of file corruption is a damaged medium, the combination
+GNU ddrescue + lziprecover is the recommended option for recovering data
+from damaged lzip files.
+
+If a file is too damaged for lziprecover to repair it, all the recoverable
+data in all members of the file can be extracted in one step with the
+command 'lziprecover -cd -i file.lz > file'.
+
+When recovering data, lziprecover takes as arguments the names of the
+damaged files and writes zero or more recovered files depending on the
+operation selected and whether the recovery succeeded or not. The damaged
+files themselves are kept unchanged.
+
+When decompressing or testing file integrity, lziprecover behaves like lzip
+or lunzip.
+
+To give you an idea of its possibilities, when merging two copies, each of
+them with one damaged area affecting 1 percent of the copy, the probability
+of obtaining a correct file is about 98 percent. With three such copies the
+probability rises to 99.97 percent. For large files (a few MB) with small
+errors (one sector damaged per copy), the probability approaches 100 percent
+even with only two copies. (Supposing that the errors are randomly located
+inside each copy).
+
+The lziprecover package also includes unzcrash, a program written to test
+robustness to decompression of corrupted data, inspired by unzcrash.c from
+Julian Seward's bzip2. Type 'make unzcrash' in the lziprecover source
+directory to build it. Then try 'unzcrash --help'.
+
+
+Copyright (C) 2009-2022 Antonio Diaz Diaz.
+
+This file is free documentation: you have unlimited permission to copy,
+distribute, and modify it.
+
+The file Makefile.in is a data file used by configure to produce the
+Makefile. It has the same copyright owner and permissions that configure
+itself.