Core: Internal: mv Base dec -> Base, Hash.decode(Base->DigestWith)

Author: Anton-Latukha

hnix-store-core/src/System/Nix/Hash.hs

@@ -15,7 +15,7 @@ module System.Nix.Hash
 
   , Base.BaseEncoding(..)
   , Hash.encodeDigestWith
-  , Hash.decodeBase
+  , Hash.decodeDigestWith
   )
 where
 

hnix-store-core/src/System/Nix/Internal/Base.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP #-}
+
 module System.Nix.Internal.Base
   ( module System.Nix.Internal.Base
   , Base32.encode
@@ -26,3 +28,18 @@ encodeWith :: BaseEncoding -> Bytes.ByteString -> T.Text
 encodeWith Base16 = T.decodeUtf8 . Base16.encode
 encodeWith NixBase32 = Base32.encode
 encodeWith Base64 = T.decodeUtf8 . Base64.encode
+
+-- | Take the input & @Base@ encoding witness -> decode into @Text@.
+decodeWith :: BaseEncoding -> T.Text -> Either String Bytes.ByteString
+#if MIN_VERSION_base16_bytestring(1,0,0)
+decodeWith Base16 = Base16.decode . T.encodeUtf8
+#else
+decodeWith Base16 = lDecode  -- this tacit sugar simply makes GHC pleased with number of args
+ where
+  lDecode t =
+    case Base16.decode (T.encodeUtf8 t) of
+      (x, "") -> pure $ x
+      _       -> Left $ "Unable to decode base16 string" <> T.unpack t
+#endif
+decodeWith NixBase32 = Base32.decode
+decodeWith Base64 = Base64.decode . T.encodeUtf8

hnix-store-core/src/System/Nix/Internal/Hash.hs

@@ -19,24 +19,21 @@ import qualified Crypto.Hash.SHA1       as SHA1
 import qualified Crypto.Hash.SHA256     as SHA256
 import qualified Crypto.Hash.SHA512     as SHA512
 import qualified Data.ByteString        as BS
-import qualified Data.ByteString.Base16 as Base16
-import qualified System.Nix.Base32      as Base32  -- Nix has own Base32 encoding
-import qualified Data.ByteString.Base64 as Base64
 import           Data.Bits              (xor)
 import qualified Data.ByteString.Lazy   as BSL
 import qualified Data.Hashable          as DataHashable
 import           Data.List              (foldl')
 import           Data.Proxy             (Proxy(Proxy))
 import           Data.Text              (Text)
 import qualified Data.Text              as T
-import qualified Data.Text.Encoding     as T
 import           Data.Word              (Word8)
 import qualified GHC.TypeLits           as Kind
                                         (Nat, KnownNat, natVal)
 import           Data.Coerce            (coerce)
 import           System.Nix.Internal.Base
                                         ( BaseEncoding(Base16,NixBase32,Base64)
                                         , encodeWith
+                                        , decodeWith
                                         )
 
 -- | The universe of supported hash algorithms.
@@ -116,9 +113,9 @@ mkNamedDigest name sriHash =
     _        -> Left $ "Unknown hash name: " <> T.unpack name
   decodeGo :: forall a . (NamedAlgo a, ValidAlgo a) => Text -> Either String (Digest a)
   decodeGo h
-    | size == base16Len = decodeBase Base16 h
-    | size == base32Len = decodeBase NixBase32 h
-    | size == base64Len = decodeBase Base64 h
+    | size == base16Len = decodeDigestWith Base16 h
+    | size == base32Len = decodeDigestWith NixBase32 h
+    | size == base64Len = decodeDigestWith Base64 h
     | otherwise = Left $ T.unpack sriHash <> " is not a valid " <> T.unpack name <> " hash. Its length (" <> show size <> ") does not match any of " <> show [base16Len, base32Len, base64Len]
    where
     size = T.length h
@@ -154,18 +151,8 @@ encodeDigestWith b = encodeWith b . coerce
 
 
 -- | Take BaseEncoding type of the input -> take the input itself -> decodeBase into Digest
-decodeBase :: BaseEncoding -> T.Text -> Either String (Digest a)
-#if MIN_VERSION_base16_bytestring(1,0,0)
-decodeBase Base16 = fmap Digest . Base16.decode . T.encodeUtf8
-#else
-decodeBase Base16 = lDecode  -- this tacit sugar simply makes GHC pleased with number of args
- where
-  lDecode t = case Base16.decode (T.encodeUtf8 t) of
-    (x, "") -> Right $ Digest x
-    _       -> Left $ "Unable to decode base16 string" <> T.unpack t
-#endif
-decodeBase NixBase32 = fmap Digest . Base32.decode
-decodeBase Base64 = fmap Digest . Base64.decode . T.encodeUtf8
+decodeDigestWith :: BaseEncoding -> T.Text -> Either String (Digest a)
+decodeDigestWith b x = Digest <$> decodeWith b x
 
 
 -- | Uses "Crypto.Hash.MD5" from cryptohash-md5.

hnix-store-core/src/System/Nix/Internal/StorePath.hs

@@ -17,7 +17,7 @@ import           System.Nix.Hash                ( HashAlgorithm
                                                 , Digest
                                                 , BaseEncoding(..)
                                                 , encodeDigestWith
-                                                , decodeBase
+                                                , decodeDigestWith
                                                 , SomeNamedDigest
                                                 )
 
@@ -178,7 +178,7 @@ parsePath expectedRoot x =
   let
     (rootDir, fname) = FilePath.splitFileName . Bytes.Char8.unpack $ x
     (digestPart, namePart) = Text.breakOn "-" $ Text.pack fname
-    digest = decodeBase NixBase32 digestPart
+    digest = decodeDigestWith NixBase32 digestPart
     name = makeStorePathName . Text.drop 1 $ namePart
     --rootDir' = dropTrailingPathSeparator rootDir
     -- cannot use ^^ as it drops multiple slashes /a/b/// -> /a/b
@@ -200,7 +200,7 @@ pathParser expectedRoot = do
       <?> "Expecting path separator"
 
   digest <-
-    decodeBase NixBase32
+    decodeDigestWith NixBase32
     <$> Parser.Text.Lazy.takeWhile1 (`elem` Nix.Base32.digits32)
       <?> "Invalid Base32 part"
 

hnix-store-core/tests/Hash.hs

@@ -55,7 +55,7 @@ prop_nixBase32Roundtrip = forAllShrink nonEmptyString genericShrink $
 
 -- | API variants
 prop_nixBase16Roundtrip :: Digest StorePathHashAlgo -> Property
-prop_nixBase16Roundtrip x = pure x === (decodeBase Base16 . encodeDigestWith Base16 $ x)
+prop_nixBase16Roundtrip x = pure x === (decodeDigestWith Base16 . encodeDigestWith Base16 $ x)
 
 -- | Hash encoding conversion ground-truth.
 -- Similiar to nix/tests/hash.sh