Merging upstream version 1.2~rc1.
Signed-off-by: Daniel Baumann <daniel@debian.org>
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@ -11,7 +11,7 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir)
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Plzip Manual
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************
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This manual is for Plzip (version 1.2-pre1, 20 January 2014).
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This manual is for Plzip (version 1.2-rc1, 8 May 2014).
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* Menu:
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@ -48,29 +48,46 @@ but on files of only a few MB plzip is no faster than lzip.
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fully compatible with lzip-1.4 or newer, and can be rescued with
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lziprecover.
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The lzip file format is designed for long-term data archiving and
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provides very safe integrity checking. The member trailer stores the
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32-bit CRC of the original data, the size of the original data and the
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size of the member. These values, together with the value remaining in
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the range decoder and the end-of-stream marker, provide a 4 factor
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integrity checking which guarantees that the decompressed version of the
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data is identical to the original. This guards against corruption of the
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compressed data, and against undetected bugs in plzip (hopefully very
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unlikely). The chances of data corruption going undetected are
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microscopic. Be aware, though, that the check occurs upon decompression,
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so it can only tell you that something is wrong. It can't help you
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recover the original uncompressed data.
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The lzip file format is designed for long-term data archiving, taking
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into account both data integrity and decoder availability:
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If you ever need to recover data from a damaged lzip file, try the
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lziprecover program. Lziprecover makes lzip files resistant to bit-flip
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(one of the most common forms of data corruption), and provides data
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recovery capabilities, including error-checked merging of damaged copies
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of a file.
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* The lzip format provides very safe integrity checking and some data
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recovery means. The lziprecover program can repair bit-flip errors
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(one of the most common forms of data corruption) in lzip files,
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and provides data recovery capabilities, including error-checked
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merging of damaged copies of a file.
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* The lzip format is as simple as possible (but not simpler). The
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lzip manual provides the code of a simple decompressor along with
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a detailed explanation of how it works, so that with the only help
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of the lzip manual it would be possible for a digital
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archaeologist to extract the data from a lzip file long after
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quantum computers eventually render LZMA obsolete.
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* Additionally lzip is copylefted, which guarantees that it will
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remain free forever.
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The member trailer stores the 32-bit CRC of the original data, the
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size of the original data and the size of the member. These values,
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together with the value remaining in the range decoder and the
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end-of-stream marker, provide a 4 factor integrity checking which
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guarantees that the decompressed version of the data is identical to
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the original. This guards against corruption of the compressed data,
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and against undetected bugs in plzip (hopefully very unlikely). The
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chances of data corruption going undetected are microscopic. Be aware,
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though, that the check occurs upon decompression, so it can only tell
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you that something is wrong. It can't help you recover the original
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uncompressed data.
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Plzip uses the same well-defined exit status values used by lzip and
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bzip2, which makes it safer than compressors returning ambiguous warning
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values (like gzip) when it is used as a back end for tar or zutils.
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Plzip will automatically use the smallest possible dictionary size
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for each file without exceeding the given limit. Keep in mind that the
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decompression memory requirement is affected at compression time by the
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choice of dictionary size limit.
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When compressing, plzip replaces every file given in the command line
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with a compressed version of itself, with the name "original_name.lz".
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When decompressing, plzip attempts to guess the name for the
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@ -215,7 +232,7 @@ The format for running plzip is:
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'--dictionary-size=BYTES'
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Set the dictionary size limit in bytes. Valid values range from 4
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KiB to 512 MiB. Plzip will use the smallest possible dictionary
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size for each member without exceeding this limit. Note that
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size for each file without exceeding this limit. Note that
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dictionary sizes are quantized. If the specified size does not
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match one of the valid sizes, it will be rounded upwards by adding
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up to (BYTES / 16) to it.
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@ -401,13 +418,13 @@ Concept index
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Tag Table:
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Node: Top221
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Node: Introduction878
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Node: Program design4650
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Node: Invoking plzip5704
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Ref: --data-size6149
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Node: File format11300
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Node: Problems13805
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Node: Concept index14334
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Node: Introduction872
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Node: Program design5441
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Node: Invoking plzip6495
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Ref: --data-size6940
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Node: File format12089
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Node: Problems14594
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Node: Concept index15123
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End Tag Table
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