Avoid crashing when built with MagicMime support, but when the magic database cannot be loaded.

Annex/FileMatcher.hs

@@ -129,8 +129,10 @@ preferredContentParser matchstandard matchgroupwanted getgroupmap configmap mu e
 mkLargeFilesParser :: Annex (String -> [ParseResult])
 mkLargeFilesParser = do
 #ifdef WITH_MAGICMIME
-	magicmime <- liftIO $ magicOpen [MagicMimeType]
-	liftIO $ magicLoadDefault magicmime
+	magicmime <- liftIO $ catchMaybeIO $ do
+		m <- magicOpen [MagicMimeType]
+		liftIO $ magicLoadDefault m
+		return m
 #endif
 	let parse = parseToken $ commonTokens
 #ifdef WITH_MAGICMIME

Limit.hs

@@ -97,14 +97,15 @@ matchGlobFile glob = go
 	go (MatchingInfo af _ _ _) = matchGlob cglob <$> getInfo af
 
 #ifdef WITH_MAGICMIME
-matchMagic :: Magic -> MkLimit Annex
-matchMagic magic glob = Right $ const go
+matchMagic :: Maybe Magic -> MkLimit Annex
+matchMagic (Just magic) glob = Right $ const go
   where
  	cglob = compileGlob glob CaseSensative -- memoized
 	go (MatchingKey _) = pure False
 	go (MatchingFile fi) = liftIO $ catchBoolIO $
 		matchGlob cglob <$> magicFile magic (matchFile fi)
 	go (MatchingInfo _ _ _ mimeval) = matchGlob cglob <$> getInfo mimeval
+matchMagic Nothing _ = Left "unable to load magic database; \"mimetype\" cannot be used"
 #endif
 
 {- Adds a limit to skip files not believed to be present

debian/changelog

@@ -9,6 +9,8 @@ git-annex (6.20160218) UNRELEASED; urgency=medium
   * info: Mention when run in a dead repository.
   * Linux and OSX standalone builds put the bundled gpg last in PATH,
     so any system gpg will be preferred over it.
+  * Avoid crashing when built with MagicMime support, but when the magic
+    database cannot be loaded.
 
  -- Joey Hess <id@joeyh.name>  Thu, 18 Feb 2016 13:09:21 -0400