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Diffstat (limited to 'doc/plzip.info')
| -rw-r--r-- | doc/plzip.info | 71 |
1 files changed, 44 insertions, 27 deletions
diff --git a/doc/plzip.info b/doc/plzip.info index 717471c..77c7640 100644 --- a/doc/plzip.info +++ b/doc/plzip.info @@ -11,7 +11,7 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir) Plzip Manual ************ -This manual is for Plzip (version 1.2-pre1, 20 January 2014). +This manual is for Plzip (version 1.2-rc1, 8 May 2014). * Menu: @@ -48,29 +48,46 @@ but on files of only a few MB plzip is no faster than lzip. 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. - - 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. + The lzip file format is designed for long-term data 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. + + * 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. + + * Additionally lzip is copylefted, which guarantees that it will + remain free forever. + + 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 @@ -215,7 +232,7 @@ The format for running plzip is: '--dictionary-size=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 + size for each 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 (BYTES / 16) to it. @@ -401,13 +418,13 @@ Concept index Tag Table: Node: Top221 -Node: Introduction878 -Node: Program design4650 -Node: Invoking plzip5704 -Ref: --data-size6149 -Node: File format11300 -Node: Problems13805 -Node: Concept index14334 +Node: Introduction872 +Node: Program design5441 +Node: Invoking plzip6495 +Ref: --data-size6940 +Node: File format12089 +Node: Problems14594 +Node: Concept index15123 End Tag Table |