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Merging upstream version 1.2~rc1.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-24 04:04:08 +01:00
parent bf5f23daeb
commit fb976cb29b
Signed by: daniel
GPG key ID: FBB4F0E80A80222F
17 changed files with 288 additions and 217 deletions
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61
doc/plzip.texi
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@ -6,8 +6,8 @@
@finalout
@c %**end of header
@set UPDATED 20 January 2014
@set VERSION 1.2-pre1
@set UPDATED 8 May 2014
@set VERSION 1.2-rc1
@dircategory Data Compression
@direntry
@ -68,29 +68,50 @@ but on files of only a few MB plzip is no faster than lzip.
Plzip uses the lzip file format; the files produced by plzip are fully
compatible with lzip-1.4 or newer, and can be rescued with lziprecover.
The lzip file format is designed for long-term data archiving and
provides very safe integrity checking. The member trailer stores the
32-bit CRC of the original data, the size of the original data and the
size of the member. These values, together with the value remaining in
the range decoder and the end-of-stream marker, provide a 4 factor
integrity checking which guarantees that the decompressed version of the
data is identical to the original. This guards against corruption of the
compressed data, and against undetected bugs in plzip (hopefully very
unlikely). The chances of data corruption going undetected are
microscopic. Be aware, though, that the check occurs upon decompression,
so it can only tell you that something is wrong. It can't help you
recover the original uncompressed data.
The lzip file format is designed for long-term data archiving, taking
into account both data integrity and decoder availability:
If you ever need to recover data from a damaged lzip file, try the
lziprecover program. Lziprecover makes lzip files resistant to bit-flip
(one of the most common forms of data corruption), and provides data
recovery capabilities, including error-checked merging of damaged copies
of a file.
@itemize @bullet
@item
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.
@item
The lzip format is as simple as possible (but not simpler). The lzip
manual provides the 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.
@item
Additionally lzip is copylefted, which guarantees that it will remain
free forever.
@end itemize
The member trailer stores the 32-bit CRC of the original data, the size
of the original data and the size of the member. These values, together
with the value remaining in the range decoder and the end-of-stream
marker, provide a 4 factor integrity checking which guarantees that the
decompressed version of the data is identical to the original. This
guards against corruption of the compressed data, and against undetected
bugs in plzip (hopefully very unlikely). The chances of data corruption
going undetected are microscopic. Be aware, though, that the check
occurs upon decompression, so it can only tell you that something is
wrong. It can't help you recover the original uncompressed data.
Plzip uses the same well-defined exit status values used by lzip and
bzip2, which makes it safer than compressors returning ambiguous warning
values (like gzip) when it is used as a back end for tar or zutils.
Plzip will automatically use the smallest possible dictionary size for
each file without exceeding the given limit. Keep in mind that the
decompression memory requirement is affected at compression time by the
choice of dictionary size limit.
When compressing, plzip replaces every file given in the command line
with a compressed version of itself, with the name "original_name.lz".
When decompressing, plzip attempts to guess the name for the decompressed
@ -238,7 +259,7 @@ Quiet operation. Suppress all messages.
@itemx --dictionary-size=@var{bytes}
Set the dictionary size limit in bytes. Valid values range from 4 KiB to
512 MiB. Plzip will use the smallest possible dictionary size for each
member without exceeding this limit. Note that dictionary sizes are
file without exceeding this limit. Note that dictionary sizes are
quantized. If the specified size does not match one of the valid sizes,
it will be rounded upwards by adding up to (@var{bytes} / 16) to it.