lzma-native
Provides bindings to the native liblzma library
Example usage:
The simplest possible usage:
var lzma = require('lzma-native');
var encoder = lzma.createStream();
process.stdin.pipe(encoder).pipe(process.stdout);
This mimicks the functionality of the xz
command line util.
Equivalently, one could have written
var encoder = lzma.createStream('easyEncoder', {preset: lzma.PRESET_DEFAULT, check: lzma.CHECK_CRC32})
or, for stronger and slower compression:
var encoder = lzma.createStream('easyEncoder', {preset: 9})
Here easyEncoder
corresponds to the xz
command line util, resp. its file format .xz.
For the older .lzma
format, you can just use aloneEncoder
instead.
The API is loosely based on the native API, with a few bits of wrapper code added for convenience.
Methods like stream.code
and lzma.crc32
accept Node.js Buffer
s as arguments.
Unless you set .synchronous = true
in createStream
s second parameter, the library will use its
own thread for compression (if compiled with support for that).
The encoder
object here is an instance of stream.Duplex
(see the Node.js docs),
so you could also manually perform any of the write and read operations that you’re familiar with on it.
List of encoders/decoders and options
Encoders and decoders you probably are interested in:
easyEncoder
: Creates.xz
files. Supports.preset
and.check
options.aloneEncoder
: Creates.lzma
files. Supports.preset
and a bunch of very specific options (see the liblzma C headers for details)autoDecoder
: Supports various flags. Detects input type automatically.
That is, the following is essentially (quite a slow version of) cat
:
var encoder = lzma.createStream('easyEncoder');
var decoder = lzma.createStream('autoDecoder');
process.stdin.pipe(encoder).pipe(decoder).pipe(process.stdout);
If you know specifically what you want, you may also look into these encoders:
rawDecoder
: Supports.filters
.rawEncoder
: Supports.filters
.streamEncoder
: Supports.filters
and.check
.streamDecoder
: Supports various flags.aloneDecoder
: Supports various flags.
Also, all encoders accept a .memlimit
option.
Installation
This package includes the native C library, so there is no need to install it separately.
You may want to use a somewhat recent C++ compiler, and asynchronous
compression support requires std::thread
, which is included in C++11
(but is not essential for compiling).
Licensing
The original C library package contains code under various licenses, with its core (liblzma) being public domain. See its contents for details. This wrapper is licensed under the LGPL 3 or any later version of the LGPL.