ensure that hash representations don't change in future

3 files changed, 23 insertions, 6 deletions

diff --git a/Backend/Hash.hs b/Backend/Hash.hs
index 309c0fe9f..d9a1bbc97 100644
--- a/Backend/Hash.hs
+++ b/Backend/Hash.hs
@@ -136,12 +136,6 @@ hashFile hash file filesize = do
 				=<< externalSHA command hashsize file
 	go (SkeinHash hashsize) = skeinHasher hashsize <$> L.readFile file
 
-skeinHasher :: HashSize -> (L.ByteString -> String)
-skeinHasher hashsize 
-	| hashsize == 256 = show . skein256
-	| hashsize == 512 = show . skein512
-	| otherwise = error $ "bad skein size " ++ show hashsize
-
 shaCommand :: HashSize -> Integer -> Either (L.ByteString -> String) String
 shaCommand hashsize filesize
 	| hashsize == 1 = use SysConfig.sha1 sha1
@@ -160,3 +154,9 @@ shaCommand hashsize filesize
 		 - process unless the file is large. -}
 		| filesize < 1048576 = use Nothing hasher
 		| otherwise = Right c
+
+skeinHasher :: HashSize -> (L.ByteString -> String)
+skeinHasher hashsize 
+	| hashsize == 256 = show . skein256
+	| hashsize == 512 = show . skein512
+	| otherwise = error $ "bad skein size " ++ show hashsize
diff --git a/Test.hs b/Test.hs
index 17047af5b..5cf1aea9e 100644
--- a/Test.hs
+++ b/Test.hs
@@ -58,6 +58,7 @@ import qualified Utility.InodeCache
 import qualified Utility.Env
 import qualified Utility.Matcher
 import qualified Utility.Exception
+import qualified Utility.Hash
 #ifndef mingw32_HOST_OS
 import qualified GitAnnex
 import qualified Remote.Helper.Encryptable
@@ -136,6 +137,7 @@ quickcheck =
 	, check "prop_parse_show_log" Logs.Presence.prop_parse_show_log
 	, check "prop_read_show_TrustLevel" Types.TrustLevel.prop_read_show_TrustLevel
 	, check "prop_parse_show_TrustLog" Logs.Trust.prop_parse_show_TrustLog
+	, check "prop_hashes_stable" Utility.Hash.prop_hashes_stable
 	]
   where
 	check desc prop = do
diff --git a/Utility/Hash.hs b/Utility/Hash.hs
index e90f50623..8b25998ae 100644
--- a/Utility/Hash.hs
+++ b/Utility/Hash.hs
@@ -6,6 +6,7 @@ module Utility.Hash where
 
 import Crypto.Hash
 import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString.Char8 as C8
 
 sha1 :: L.ByteString -> Digest SHA1
 sha1 = hashlazy
@@ -31,3 +32,17 @@ skein256 = hashlazy
 
 skein512 :: L.ByteString -> Digest Skein512_512
 skein512 = hashlazy
+
+{- Check that all the hashes continue to hash the same. -}
+prop_hashes_stable :: Bool
+prop_hashes_stable = all (\(hasher, result) -> hasher foo == result)
+	[ (show . sha1, "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33")
+	, (show . sha224, "0808f64e60d58979fcb676c96ec938270dea42445aeefcd3a4e6f8db")
+	, (show . sha256, "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae")
+	, (show . sha384, "98c11ffdfdd540676b1a137cb1a22b2a70350c9a44171d6b1180c6be5cbb2ee3f79d532c8a1dd9ef2e8e08e752a3babb")
+	, (show . sha512, "f7fbba6e0636f890e56fbbf3283e524c6fa3204ae298382d624741d0dc6638326e282c41be5e4254d8820772c5518a2c5a8c0c7f7eda19594a7eb539453e1ed7")
+	, (show . skein256, "a04efd9a0aeed6ede40fe5ce0d9361ae7b7d88b524aa19917b9315f1ecf00d33")
+	, (show . skein512, "fd8956898113510180aa4658e6c0ac85bd74fb47f4a4ba264a6b705d7a8e8526756e75aecda12cff4f1aca1a4c2830fbf57f458012a66b2b15a3dd7d251690a7")
+	]
+  where
+	foo = L.fromChunks [C8.pack "foo"]