lzma-streams-0.1.0.0: IO-Streams interface for lzma/xz compression

Copyright© 2015 Herbert Valerio Riedel
LicenseBSD3
Maintainerhvr@gnu.org
Stabilityexperimental
Portabilityportable
Safe HaskellNone
LanguageHaskell2010

System.IO.Streams.Lzma

Contents

Description

Simple IO-Streams interface for lzma/xz compression

See also the XZ Utils home page: http://tukaani.org/xz/

Synopsis

ByteString decompression

decompress :: InputStream ByteString -> IO (InputStream ByteString) Source

Decompress an InputStream of strict ByteStrings from the .xz format

decompressWith :: DecompressParams -> InputStream ByteString -> IO (InputStream ByteString) Source

Like decompress but with the ability to specify various decompression parameters. Typical usage:

decompressWith defaultDecompressParams { decompress... = ... }

defaultDecompressParams :: DecompressParams

The default set of parameters for decompression. This is typically used with the decompressWith function with specific parameters overridden.

data DecompressParams :: *

Set of parameters for decompression. The defaults are defaultDecompressParams.

compressIntegrityCheck :: CompressParams -> IntegrityCheck

CompressParams field: Specify type of integrity check

compressLevelExtreme :: CompressParams -> Bool

CompressParams field: Enable slower variant of the lzmaCompLevel preset, see xz(1) man-page for details.

ByteString compression

compress :: OutputStream ByteString -> IO (OutputStream ByteString) Source

Convert an OutputStream that consumes compressed ByteStrings (in the .xz format) into an OutputStream that consumes uncompressed ByteStrings

compressWith :: CompressParams -> OutputStream ByteString -> IO (OutputStream ByteString) Source

Like compress but with the ability to specify various compression parameters. Typical usage:

compressWith defaultCompressParams { compress... = ... }

defaultCompressParams :: CompressParams

The default set of parameters for compression. This is typically used with the compressWith function with specific parameters overridden.

data CompressParams :: *

Set of parameters for compression. The defaults are defaultCompressParams.

decompressTellNoCheck :: DecompressParams -> Bool

DecompressParams field: If set, abort if decoded stream has no integrity check.

decompressTellUnsupportedCheck :: DecompressParams -> Bool

DecompressParams field: If set, abort (via LzmaRetGetCheck) if decoded stream integrity check is unsupported.

decompressTellAnyCheck :: DecompressParams -> Bool

DecompressParams field: If set, abort (via LzmaRetGetCheck) as soon as the type of the integrity check has been detected.

decompressConcatenated :: DecompressParams -> Bool

DecompressParams field: If set, concatenated files as decoded seamless.

decompressAutoDecoder :: DecompressParams -> Bool

DecompressParams field: If set, legacy .lzma-encoded streams are allowed too.

decompressMemLimit :: DecompressParams -> Word64

DecompressParams field: decompressor memory limit. Set to maxBound to disable memory limit.

data IntegrityCheck :: *

Integrity check type (only supported when compressing .xz files)

Constructors

IntegrityCheckNone

disable integrity check (not recommended)

IntegrityCheckCrc32

CRC32 using the polynomial from IEEE-802.3

IntegrityCheckCrc64

CRC64 using the polynomial from ECMA-182

IntegrityCheckSha256

SHA-256

data CompressionLevel :: *

Compression level presets that define the tradeoff between computational complexity and compression ratio

CompressionLevel0 has the lowest compression ratio as well as the lowest memory requirements, whereas CompressionLevel9 has the highest compression ratio and can require over 600MiB during compression (and over 60MiB during decompression). The man-page for xz(1) contains more detailed information with tables describing the properties of all compression level presets.

CompressionLevel6 is the default setting in defaultCompressParams as it provides a good trade-off and matches the default of the xz(1) tool.