65 lines
2.3 KiB
Haskell
65 lines
2.3 KiB
Haskell
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{-# LANGUAGE CPP #-}
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#if __GLASGOW_HASKELL__ >= 702
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{-# LANGUAGE Trustworthy #-}
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#endif
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-- |
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-- Module : Data.ByteString.Base64.Lazy
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-- Copyright : (c) 2012 Ian Lynagh
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--
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-- License : BSD-style
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-- Maintainer : Emily Pillmore <emilypi@cohomolo.gy>,
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-- Herbert Valerio Riedel <hvr@gnu.org>,
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-- Mikhail Glushenkov <mikhail.glushenkov@gmail.com>
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-- Stability : experimental
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-- Portability : GHC
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--
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-- Fast and efficient encoding and decoding of base64-encoded
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-- lazy bytestrings.
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--
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-- @since 1.0.0.0
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module Data.ByteString.Base64.Lazy
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(
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encode
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, decode
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, decodeLenient
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) where
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import Data.ByteString.Base64.Internal
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import qualified Data.ByteString.Base64 as B64
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Lazy as L
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import qualified Data.ByteString.Lazy.Char8 as LC
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import Data.Char
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-- | Encode a string into base64 form. The result will always be a
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-- multiple of 4 bytes in length.
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encode :: L.ByteString -> L.ByteString
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encode = L.fromChunks . map B64.encode . reChunkIn 3 . L.toChunks
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-- | Decode a base64-encoded string. This function strictly follows
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-- the specification in
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-- <http://tools.ietf.org/rfc/rfc4648 RFC 4648>.
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decode :: L.ByteString -> Either String L.ByteString
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decode b = -- Returning an Either type means that the entire result will
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-- need to be in memory at once anyway, so we may as well
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-- keep it simple and just convert to and from a strict byte
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-- string
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-- TODO: Use L.{fromStrict,toStrict} once we can rely on
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-- a new enough bytestring
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case B64.decode $ S.concat $ L.toChunks b of
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Left err -> Left err
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Right b' -> Right $ L.fromChunks [b']
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-- | Decode a base64-encoded string. This function is lenient in
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-- following the specification from
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-- <http://tools.ietf.org/rfc/rfc4648 RFC 4648>, and will not generate
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-- parse errors no matter how poor its input.
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decodeLenient :: L.ByteString -> L.ByteString
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decodeLenient = L.fromChunks . map B64.decodeLenient . reChunkIn 4 . L.toChunks
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. LC.filter goodChar
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where -- We filter out and '=' padding here, but B64.decodeLenient
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-- handles that
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goodChar c = isDigit c || isAsciiUpper c || isAsciiLower c
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|| c == '+' || c == '/'
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