Description

Pdlzip is a lossless data compressor with a user interface similar to
the one of lzip, bzip2 or gzip.

Pdlzip uses the lzip file format; the files produced by pdlzip are
(hope)fully compatible with lzip-1.4 or newer. Pdlzip is in fact a
permissively licensed implementation of the lzip data compressor,
intended for those who can't distribute (or even use) GPL licensed Free
Software. (The name of pdlzip comes from "public domain lzip").

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.

   * 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.

Pdlzip is also able to decompress legacy lzma-alone (.lzma) files.
Lzma-alone is a very bad format; it is essentially a raw LZMA stream.
If you keep any lzma-alone files, it is advisable to recompress them to
lzip format. Lziprecover can convert some lzma-alone files to lzip format
without recompressing.

Pdlzip is written in C.

Pdlzip includes public domain (de)compression code from the LZMA SDK
(Software Development Kit) written by Igor Pavlov.

I would not write non-copylefted software unless it is too simple to be
worth copylefting it, but one of the uses of the lzip format is the
interchange of information, and it is therefore desirable that even the
users of the most non-free platforms can share lzip files with everybody
else.


Copyright (C) 2010-2018 Antonio Diaz Diaz.

This file is free documentation: you have unlimited permission to copy,
distribute and modify it.

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