Module crypto.comp
Low-level Lua interface to the Linux Kernel Crypto API for synchronous compression algorithms.
This module provides a new function to create COMP transform objects, which can then be used for compression and decompression.
Class COMP
| comp:compress (data, max_output_len) | Compresses the given data. |
| comp:decompress (data, max_output_len) | Decompresses the given data. |
comp
| new (algname) | Creates a new COMP transform (TFM) object. |
Class COMP
COMP Object methods.
These methods are available on COMP objects created by
comp.new().
- comp:compress (data, max_output_len)
-
Compresses the given data.
Requires the maximum possible compressed size as an argument, as the kernel
API needs a destination buffer of sufficient size. A common approach is to
provide a size slightly larger than the input data (e.g., input size + a small fixed overhead or percentage).
Parameters:
- data string The data to compress.
- max_output_len integer The maximum possible size of the compressed data.
Returns:
-
string
The compressed data.
Raises:
Error on failure (e.g., allocation error, crypto API error). - comp:decompress (data, max_output_len)
-
Decompresses the given data.
Requires the maximum possible decompressed size as an argument, as the kernel
API needs a destination buffer of sufficient size.
Parameters:
- data string The data to decompress.
- max_output_len integer The maximum possible size of the decompressed data.
Returns:
-
string
The decompressed data.
Raises:
Error on failure (e.g., allocation error, crypto API error, input data corrupted,
<code>max\_output\_len</code> too small).
comp
- new (algname)
-
Creates a new COMP transform (TFM) object.
This is the constructor function for the
crypto_compmodule.Parameters:
- algname string The name of the compression algorithm (e.g., "lz4", "deflate").
Returns:
-
comp
The new COMP TFM object.
Raises:
Error if the TFM object cannot be allocated/initialized.Usage:
local comp = require("crypto.comp") local compressor = comp.new("lz4")