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Merging upstream version 1.22.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-21 11:31:04 +01:00
parent fb5506e101
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README
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@ -3,8 +3,9 @@ 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, produce a correct file by merging the good parts of two or more
damaged copies, extract data from damaged files, decompress files and test
integrity of files.
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.
@ -22,68 +23,71 @@ 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 lziprecover program 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.
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.
* 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.
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.
For compressible data, multiple lzip-compressed copies have a better
chance of surviving intact than one uncompressed copy using the same
amount of storage space.
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.
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 damaged media, the combination
GNU ddrescue + lziprecover is the best option for recovering data from
multiple damaged copies.
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 '-D' option.
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.
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.
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).
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'.
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) 2009-2019 Antonio Diaz Diaz.
Copyright (C) 2009-2021 Antonio Diaz Diaz.
This file is free documentation: you have unlimited permission to copy,
distribute and modify it.
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