1 files changed, 21 insertions, 1 deletions
diff --git a/src/Hakyll/Core/Util/File.hs b/src/Hakyll/Core/Util/File.hs
index 45f3760..71de322 100644
--- a/src/Hakyll/Core/Util/File.hs
+++ b/src/Hakyll/Core/Util/File.hs
@@ -4,15 +4,21 @@ module Hakyll.Core.Util.File
     ( makeDirectories
     , getRecursiveContents
     , isFileObsolete
+    , isFileInternal
     ) where
 
-import System.FilePath (normalise, takeDirectory, (</>))
 import System.Time (ClockTime)
 import Control.Monad (forM, filterM)
+import Data.List (isPrefixOf)
 import System.Directory ( createDirectoryIfMissing, doesDirectoryExist
                         , doesFileExist, getModificationTime
                         , getDirectoryContents
                         )
+import System.FilePath ( normalise, takeDirectory, splitPath
+                       , dropTrailingPathSeparator, (</>)
+                       )
+
+import Hakyll.Core.Configuration
 
 -- | Given a path to a file, try to make the path writable by making
 --   all directories on the path.
@@ -65,3 +71,17 @@ isFileObsolete file depends = do
         then return True
         else do timeStamp <- getModificationTime file
                 isObsolete timeStamp depends
+
+-- | Check if a file is meant for Hakyll internal use, i.e. if it is located in
+-- the destination or store directory
+--
+isFileInternal :: HakyllConfiguration  -- ^ Configuration
+               -> FilePath             -- ^ File to check
+               -> Bool                 -- ^ If the given file is internal
+isFileInternal configuration file =
+    any (`isPrefixOf` split file) dirs
+  where
+    split = map dropTrailingPathSeparator . splitPath
+    dirs = map (split . ($ configuration)) [ destinationDirectory
+                                           , storeDirectory
+                                           ]