hook desktop menu file installation into makefile and cabal

Build/InstallDesktopFile.hs

@@ -0,0 +1,39 @@
+{- Generating and installing a desktop menu entry file.
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Build.InstallDesktopFile where
+
+import Utility.Exception
+import Utility.FreeDesktop
+
+import Control.Applicative
+import System.Environment
+import System.Posix.User
+
+{- The command can be either just "git-annex", or the full path to use
+ - to run it. -}
+desktop :: FilePath -> DesktopEntry
+desktop command = genDesktopEntry
+	"Git Annex"
+	"Track and sync the files in your Git Annex"
+	False
+	(command ++ " webapp")
+	["Network", "FileTransfer"]
+
+writeDesktop :: DesktopEntry -> IO ()
+writeDesktop d = do
+	destdir <- catchDefaultIO (getEnv "DESTDIR") ""
+	uid <- fromIntegral <$> getRealUserID
+	dest <- if uid /= 0
+		then userDesktopMenuFilePath "git-annex"
+		else return $ systemDesktopMenuFilePath "git-annex"
+	writeDesktopMenuFile d dest
+
+main = getArgs >>= go
+	where
+		go [] = error "specify git-annex command"
+		go (command:_) = writeDesktop $ desktop command