Merge pull request #32 from haskell-nix/readonly-store-hash

Implement readonly store path hashing

hnix-store-core/hnix-store-core.cabal

@@ -24,9 +24,11 @@ library
                      , System.Nix.Internal.Hash
                      , System.Nix.Nar
                      , System.Nix.Path
+                     , System.Nix.ReadonlyStore
                      , System.Nix.Store
                      , System.Nix.Util
   build-depends:       base >=4.10 && <4.12
+                     , base16-bytestring
                      , bytestring
                      , binary
                      , bytestring
@@ -61,7 +63,7 @@ test-suite format-tests
        NarFormat
        Hash
    hs-source-dirs:
-       tests 
+       tests
    build-depends:
        hnix-store-core
      , base

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

@@ -12,25 +12,29 @@ Maintainer  : Greg Hale <imalsogreg@gmail.com>
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeApplications    #-}
 {-# LANGUAGE TypeInType          #-}
+{-# LANGUAGE OverloadedStrings   #-}
 
 module System.Nix.Internal.Hash where
 
-import qualified Crypto.Hash.MD5       as MD5
-import qualified Crypto.Hash.SHA1      as SHA1
-import qualified Crypto.Hash.SHA256    as SHA256
-import qualified Data.ByteString       as BS
-import qualified Data.ByteString.Char8 as BSC
-import           Data.Bits             (xor)
-import qualified Data.ByteString       as BS
-import qualified Data.ByteString.Lazy  as BSL
-import qualified Data.Hashable         as DataHashable
-import           Data.Kind             (Type)
-import           Data.List             (foldl')
-import           Data.Proxy            (Proxy(Proxy))
-import qualified Data.Text             as T
-import qualified Data.Text.Encoding    as T
-import qualified Data.Vector           as V
-import           Data.Word             (Word8)
+import qualified Crypto.Hash.MD5        as MD5
+import qualified Crypto.Hash.SHA1       as SHA1
+import qualified Crypto.Hash.SHA256     as SHA256
+import qualified Data.ByteString        as BS
+import qualified Data.ByteString.Base16 as Base16
+import qualified Data.ByteString.Char8  as BSC
+import           Data.Bits              (xor)
+import qualified Data.ByteString        as BS
+import qualified Data.ByteString.Lazy   as BSL
+import qualified Data.Hashable          as DataHashable
+import           Data.Kind              (Type)
+import           Data.List              (foldl')
+import           Data.Monoid
+import           Data.Proxy             (Proxy(Proxy))
+import           Data.Text              (Text)
+import qualified Data.Text              as T
+import qualified Data.Text.Encoding     as T
+import qualified Data.Vector            as V
+import           Data.Word              (Word8)
 import           GHC.TypeLits
 
 -- | A tag for different hashing algorithms
@@ -45,6 +49,18 @@ data HashAlgorithm' n
   | Truncated n (HashAlgorithm' n)
   deriving (Eq, Show)
 
+class HashAlgoText a where
+  algoString :: Proxy a -> Text
+
+instance HashAlgoText 'MD5 where
+  algoString (Proxy :: Proxy 'MD5) = "md5"
+
+instance HashAlgoText 'SHA1 where
+  algoString (Proxy :: Proxy 'SHA1) = "sha1"
+
+instance HashAlgoText 'SHA256 where
+  algoString (Proxy :: Proxy 'SHA256) = "sha256"
+
 type HashAlgorithm = HashAlgorithm' Nat
 
 -- | Types with kind @HashAlgorithm@ may be a @HasDigest@ instance
@@ -80,8 +96,11 @@ hashLazy :: forall a.HasDigest a => BSL.ByteString -> Digest a
 hashLazy bsl =
   finalize $ foldl' (update @a) (initialize @a) (BSL.toChunks bsl)
 
+digestText32 :: forall a. HashAlgoText a => Digest a -> T.Text
+digestText32 d = algoString (Proxy :: Proxy a) <> ":" <> printAsBase32 d
 
-
+digestText16 :: forall a. HashAlgoText a => Digest a -> T.Text
+digestText16 (Digest bs) = algoString (Proxy :: Proxy a) <> ":" <> T.decodeUtf8 (Base16.encode bs)
 
 -- | Convert any Digest to a base32-encoded string.
 --   This is not used in producing store path hashes

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

@@ -3,11 +3,13 @@ Description : Types and effects for interacting with the Nix store.
 Maintainer  : Shea Levy <shea@shealevy.com>
 -}
 {-# LANGUAGE DataKinds                  #-}
+{-# LANGUAGE OverloadedStrings          #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 module System.Nix.Path
   ( FilePathPart(..)
   , PathHashAlgo
   , Path(..)
+  , pathToText
   , PathSet
   , SubstitutablePathInfo(..)
   , ValidPathInfo(..)
@@ -19,12 +21,14 @@ module System.Nix.Path
 
 import           System.Nix.Hash           (Digest(..),
                                             HashAlgorithm'(Truncated, SHA256))
+import           System.Nix.Internal.Hash
 import qualified Data.ByteString           as BS
 import qualified Data.ByteString.Char8     as BSC
 import           Data.Hashable             (Hashable (..), hashPtrWithSalt)
 import           Data.HashMap.Strict       (HashMap)
 import           Data.HashSet              (HashSet)
 import           Data.Map.Strict           (Map)
+import           Data.Monoid
 import           Data.Text                 (Text)
 import qualified Data.Text                 as T
 import           System.IO.Unsafe          (unsafeDupablePerformIO)
@@ -46,7 +50,7 @@ newtype PathName = PathName
 -- | A regular expression for matching a valid 'PathName'
 nameRegex :: Regex
 nameRegex =
-  makeRegex "[a-zA-Z0-9\\+\\-\\_\\?\\=][a-zA-Z0-9\\+\\-\\.\\_\\?\\=]*"
+  makeRegex ("[a-zA-Z0-9\\+\\-\\_\\?\\=][a-zA-Z0-9\\+\\-\\.\\_\\?\\=]*" :: String)
 
 -- | Construct a 'PathName', assuming the provided contents are valid.
 pathName :: Text -> Maybe PathName
@@ -58,6 +62,9 @@ pathName n = case matchTest nameRegex n of
 data Path = Path !(Digest PathHashAlgo) !PathName
   deriving (Eq, Ord, Show)
 
+pathToText :: Text -> Path -> Text
+pathToText storeDir (Path h nm) = storeDir <> "/" <> printAsBase32 h <> "-" <> pathNameContents nm
+
 type PathSet = HashSet Path
 
 -- | Information about substitutes for a 'Path'.

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

@@ -0,0 +1,33 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+module System.Nix.ReadonlyStore where
+
+import           Data.ByteString (ByteString)
+import           Data.ByteString.Base16 as Base16
+import qualified Data.HashSet as HS
+import           Data.Text (Text)
+import qualified Data.Text as T
+import           Data.Text.Encoding
+import           System.Nix.Internal.Hash
+import           System.Nix.Path
+
+makeStorePath :: Text -> Text -> Digest 'SHA256 -> Text -> Path
+makeStorePath storeDir ty h nm = Path storeHash (PathName nm)
+  where
+    s = T.intercalate ":"
+      [ ty
+      , digestText16 h
+      , storeDir
+      , nm
+      ]
+    storeHash = truncateDigest $ hash $ encodeUtf8 s
+
+makeTextPath :: Text -> Text -> Digest 'SHA256 -> PathSet -> Path
+makeTextPath storeDir nm h refs = makeStorePath storeDir ty h nm
+  where
+    ty = T.intercalate ":" ("text" : map (pathToText storeDir) (HS.toList refs))
+
+computeStorePathForText :: Text -> Text -> ByteString -> PathSet -> Path
+computeStorePathForText storeDir nm s refs = makeTextPath storeDir nm (hash s) refs