src/Ganeti/Codec.hs

{-| Provides interface to the 'zlib' library.

-}

{-

Copyright (C) 2014 Google Inc.
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-}

module Ganeti.Codec
  ( compressZlib
  , decompressZlib
  ) where

import Prelude ()
import Ganeti.Prelude

import Codec.Compression.Zlib
import qualified Codec.Compression.Zlib.Internal as I
import Control.Monad (liftM)
import Control.Monad.Error.Class (MonadError(..))
import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString.Lazy.Internal as BL

import Ganeti.BasicTypes


-- | Compresses a lazy bytestring.
compressZlib :: BL.ByteString -> BL.ByteString
compressZlib = compressWith $
  defaultCompressParams { compressLevel = CompressionLevel 3 }

-- | Decompresses a lazy bytestring, throwing decoding errors using
-- 'throwError'.
decompressZlib :: (MonadError e m, FromString e)
               => BL.ByteString -> m BL.ByteString
decompressZlib = I.foldDecompressStream
                     (liftM . BL.chunk)
                     (return mempty)
                     (const $ throwError . mkFromString . ("Zlib: " ++))
                 . I.decompressWithErrors
                     I.zlibFormat
                     I.defaultDecompressParams