Codec.Compression.Lzma

Compression and decompression of data streams in the lzma/xz format

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

Simple (de)compression

compress :: ByteString -> ByteString

Compress lazy ByteString into .xz format using defaultCompressParams.

decompress :: ByteString -> ByteString

Decompress lazy ByteString from the .xz format

Extended API with control over parameters

compressWith :: CompressParams -> ByteString -> ByteString

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

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

decompressWith :: DecompressParams -> ByteString -> ByteString

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

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

Monadic incremental (de)compression API

See zlib's incremental API documentation for more information.

Compression

data CompressStream m

Constructors

CompressInputRequired (m (CompressStream m)) (ByteString -> m (CompressStream m))

Compression process requires input to proceed. You can either flush the stream (first field), supply an input chunk (second field), or signal the end of input (via empty chunk).

CompressOutputAvailable !ByteString (m (CompressStream m))

Output chunk available.

CompressStreamEnd

compressIO :: CompressParams -> IO (CompressStream IO)

Incremental compression in the IO monad.

compressST :: CompressParams -> ST s (CompressStream (ST s))

Incremental compression in the lazy ST monad.

Decompression

data DecompressStream m

Constructors

DecompressInputRequired (ByteString -> m (DecompressStream m))

Decoding process requires input to proceed. An empty ByteString chunk signals end of input.

DecompressOutputAvailable !ByteString (m (DecompressStream m))

Decompressed output chunk available.

DecompressStreamEnd ByteString

Decoded stream is finished. Any unconsumed leftovers from the input stream are returned via the ByteString field

DecompressStreamError !LzmaRet

decompressIO :: DecompressParams -> IO (DecompressStream IO)

Incremental decompression in the IO monad.

decompressST :: DecompressParams -> ST s (DecompressStream (ST s))

Incremental decompression in the lazy ST monad.

data LzmaRet

Constructors

LzmaRetOK

LzmaRetStreamEnd

LzmaRetUnsupportedCheck

LzmaRetGetCheck

LzmaRetMemError

LzmaRetMemlimitError

LzmaRetFormatError

LzmaRetOptionsError

LzmaRetDataError

LzmaRetBufError

LzmaRetProgError

Instances

Eq LzmaRet

Ord LzmaRet

Read LzmaRet

Show LzmaRet

Exception LzmaRet

Typeable * LzmaRet

Parameters

Compression parameters

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.

Instances

Eq CompressParams

Show CompressParams

compressIntegrityCheck :: CompressParams -> IntegrityCheck

CompressParams field: Specify type of integrity check

compressLevel :: CompressParams -> CompressionLevel

CompressParams field: See documentation of CompressionLevel

compressLevelExtreme :: CompressParams -> Bool

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

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

Instances

Eq IntegrityCheck

Ord IntegrityCheck

Read IntegrityCheck

Show IntegrityCheck

Typeable * IntegrityCheck

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.

Constructors

CompressionLevel0

CompressionLevel1

CompressionLevel2

CompressionLevel3

CompressionLevel4

CompressionLevel5

CompressionLevel6

CompressionLevel7

CompressionLevel8

CompressionLevel9

Instances

Enum CompressionLevel

Eq CompressionLevel

Ord CompressionLevel

Read CompressionLevel

Show CompressionLevel

Typeable * CompressionLevel

Decompression parameters

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.

Instances

Eq DecompressParams

Show DecompressParams

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.