1 files changed, 63 insertions, 0 deletions
diff --git a/src/Propellor/Property/File.hs b/src/Propellor/Property/File.hs
index 95fc6f81..869fa48b 100644
--- a/src/Propellor/Property/File.hs
+++ b/src/Propellor/Property/File.hs
@@ -6,8 +6,10 @@ import Propellor.Base
 import Utility.FileMode
 
 import qualified Data.ByteString.Lazy as L
+import Data.List (isInfixOf, isPrefixOf)
 import System.Posix.Files
 import System.Exit
+import Data.Char
 
 type Line = String
 
@@ -21,11 +23,33 @@ f `hasContent` newcontent = fileProperty
 containsLine :: FilePath -> Line -> Property UnixLike
 f `containsLine` l = f `containsLines` [l]
 
+-- | Ensures that a list of lines are present in a file, adding any that are not
+-- to the end of the file.
+--
+-- Note that this property does not guarantee that the lines will appear
+-- consecutively, nor in the order specified.  If you need either of these, use
+-- 'File.containsBlock'.
 containsLines :: FilePath -> [Line] -> Property UnixLike
 f `containsLines` ls = fileProperty (f ++ " contains:" ++ show ls) go f
   where
 	go content = content ++ filter (`notElem` content) ls
 
+-- | Ensures that a block of consecutive lines is present in a file, adding it
+-- to the end if not.  Revert to ensure that the block is not present (though
+-- the lines it contains could be present, non-consecutively).
+containsBlock :: FilePath -> [Line] -> RevertableProperty UnixLike UnixLike
+f `containsBlock` ls =
+	fileProperty (f ++ " contains block:" ++ show ls) add f
+	<!> fileProperty (f ++ " lacks block:" ++ show ls) remove f
+  where
+	add content
+		| ls `isInfixOf` content = content
+		| otherwise              = content ++ ls
+	remove [] = []
+	remove content@(x:xs)
+		| ls `isPrefixOf` content = remove (drop (length ls) content)
+		| otherwise = x : remove xs
+
 -- | Ensures that a line is not present in a file.
 -- Note that the file is ensured to exist, so if it doesn't, an empty
 -- file will be written.
@@ -221,3 +245,42 @@ viaStableTmp a f = bracketIO setup cleanup go
 	go tmpfile = do
 		a tmpfile
 		liftIO $ rename tmpfile f
+
+-- | Generates a base configuration file name from a String, which
+-- can be put in a configuration directory, such as
+-- </etc/apt/sources.list.d/>
+--
+-- The generated file name is limited to using ASCII alphanumerics,
+-- \'_\' and \'.\' , so that programs that only accept a limited set of
+-- characters will accept it. Any other characters will be encoded
+-- in escaped form.
+--
+-- Some file extensions, such as ".old" may be filtered out by
+-- programs that use configuration directories. To avoid such problems,
+-- it's a good idea to add an static prefix and extension to the 
+-- result of this function. For example:
+--
+-- > aptConf foo = "/etc/apt/apt.conf.d" </> "propellor_" ++ configFileName foo <.> ".conf"
+configFileName :: String -> FilePath
+configFileName = concatMap escape
+  where
+	escape c
+		| isAscii c && isAlphaNum c = [c]
+		| c == '.' = [c]
+		| otherwise = '_' : show (ord c)
+
+-- | Applies configFileName to any value that can be shown.
+showConfigFileName :: Show v => v -> FilePath
+showConfigFileName = configFileName . show
+
+-- | Inverse of showConfigFileName.
+readConfigFileName :: Read v => FilePath -> Maybe v
+readConfigFileName = readish . unescape
+  where
+	unescape [] = []
+	unescape ('_':cs) = case break (not . isDigit) cs of
+		([], _) -> '_' : unescape cs
+		(ns, cs') -> case readish ns of
+			Nothing -> '_' : ns ++ unescape cs'
+			Just n -> chr n : unescape cs'
+	unescape (c:cs) = c : unescape cs