Generate shorter keys for WORM and URL, avoiding keys that are longer than used for SHA256, so as to not break on systems like Windows that have very small maximum path length limits.

4 files changed, 24 insertions, 19 deletions

diff --git a/Backend/URL.hs b/Backend/URL.hs
index 2c2988ac0..ac517a5f3 100644
--- a/Backend/URL.hs
+++ b/Backend/URL.hs
@@ -32,10 +32,8 @@ backend = Backend
 
 {- Every unique url has a corresponding key. -}
 fromUrl :: String -> Maybe Integer -> Annex Key
-fromUrl url size = do
-	n <- genKeyName url
-	return $ stubKey
-		{ keyName = n
-		, keyBackendName = "URL"
-		, keySize = size
-		}
+fromUrl url size = return $ stubKey
+	{ keyName = genKeyName url
+	, keyBackendName = "URL"
+	, keySize = size
+	}
diff --git a/Backend/Utilities.hs b/Backend/Utilities.hs
index 24dbfd6d9..6426353e7 100644
--- a/Backend/Utilities.hs
+++ b/Backend/Utilities.hs
@@ -13,13 +13,18 @@ import Common.Annex
 
 {- Generates a keyName from an input string. Takes care of sanitizing it.
  - If it's not too long, the full string is used as the keyName.
- - Otherwise, it's truncated at half the filename length limit, and its
- - md5 is prepended to ensure a unique key. -}
-genKeyName :: String -> Annex String
-genKeyName s = do
-	limit <- liftIO . fileNameLengthLimit =<< fromRepo gitAnnexDir
-	let s' = preSanitizeKeyName s
-	let truncs = truncateFilePath (limit `div` 2) s'
-	return $ if s' == truncs
-		then s'
-		else truncs ++ "-" ++ md5s (Str s)
+ - Otherwise, it's truncated, and its md5 is prepended to ensure a unique
+ - key. -}
+genKeyName :: String -> String
+genKeyName s
+	-- Avoid making keys longer than the length of a SHA256 checksum.
+	| bytelen > sha256len =
+		truncateFilePath (sha256len - md5len - 1) s' ++ "-" ++ md5s (Str s)
+	| otherwise = s'
+  where
+	s' = preSanitizeKeyName s
+	bytelen = length (decodeW8 s')
+
+	sha256len = 64
+	md5len = 32
+
diff --git a/Backend/WORM.hs b/Backend/WORM.hs
index de7779bb3..bd5e374e1 100644
--- a/Backend/WORM.hs
+++ b/Backend/WORM.hs
@@ -34,9 +34,8 @@ keyValue :: KeySource -> Annex (Maybe Key)
 keyValue source = do
 	stat <- liftIO $ getFileStatus $ contentLocation source
 	relf <- getTopFilePath <$> inRepo (toTopFilePath $ keyFilename source)
-	n <- genKeyName relf
 	return $ Just $ stubKey
-		{ keyName = n
+		{ keyName = genKeyName relf
 		, keyBackendName = name backend
 		, keySize = Just $ fromIntegral $ fileSize stat
 		, keyMtime = Just $ modificationTime stat
diff --git a/debian/changelog b/debian/changelog
index 908636f05..40a0a6707 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -12,6 +12,9 @@ git-annex (5.20141232) UNRELEASED; urgency=medium
   * Check git version at runtime, rather than assuming it will be the same
     as the git version used at build time when running git-checkattr and
     git-branch remove.
+  * Generate shorter keys for WORM and URL, avoiding keys that are longer
+    than used for SHA256, so as to not break on systems like Windows that
+    have very small maximum path length limits.
 
  -- Joey Hess <id@joeyh.name>  Fri, 02 Jan 2015 13:35:13 -0400