3 files changed, 76 insertions, 2 deletions
diff --git a/src/CabalHelper/Compiletime/Compile.hs b/src/CabalHelper/Compiletime/Compile.hs
index c1c3bc4..2f4b0a9 100644
--- a/src/CabalHelper/Compiletime/Compile.hs
+++ b/src/CabalHelper/Compiletime/Compile.hs
@@ -58,10 +58,11 @@ import CabalHelper.Compiletime.Data
 import CabalHelper.Compiletime.Log
 import CabalHelper.Compiletime.Program.GHC
 import CabalHelper.Compiletime.Program.CabalInstall
+import CabalHelper.Compiletime.Sandbox
+    ( getSandboxPkgDb )
 import CabalHelper.Compiletime.Types
 
 import CabalHelper.Shared.Common
-import CabalHelper.Shared.Sandbox (getSandboxPkgDb)
 
 data Compile
     = CompileWithCabalSource
diff --git a/src/CabalHelper/Compiletime/Data.hs b/src/CabalHelper/Compiletime/Data.hs
index 9fb5a53..07cf2d2 100644
--- a/src/CabalHelper/Compiletime/Data.hs
+++ b/src/CabalHelper/Compiletime/Data.hs
@@ -87,7 +87,6 @@ runtimeSources = $(
         [ ("Runtime/Main.hs")
         , ("Runtime/Compat.hs")
         , ("Shared/Common.hs")
-        , ("Shared/Sandbox.hs")
         , ("Shared/InterfaceTypes.hs")
         ]
   in do
diff --git a/src/CabalHelper/Compiletime/Sandbox.hs b/src/CabalHelper/Compiletime/Sandbox.hs
new file mode 100644
index 0000000..5af226a
--- /dev/null
+++ b/src/CabalHelper/Compiletime/Sandbox.hs
@@ -0,0 +1,74 @@
+-- cabal-helper: Simple interface to Cabal's configuration state
+-- Copyright (C) 2015-2017  Daniel Gröber <cabal-helper@dxld.at>
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+{-|
+Module      : CabalHelper.Shared.Sandbox
+Description : Extracting information from @cabal.sandbox.config@ files
+License     : GPL-3
+-}
+
+module CabalHelper.Compiletime.Sandbox where
+
+import Control.Applicative
+import Data.Char
+import Data.Maybe
+import Data.List
+import Data.Version
+import System.FilePath
+import Prelude
+
+import qualified Data.Traversable as T
+
+import CabalHelper.Shared.Common
+
+-- | Get the path to the sandbox package-db in a project
+getSandboxPkgDb :: String
+             -- ^ Cabal build platform, i.e. @buildPlatform@
+             -> Version
+             -- ^ GHC version (@cProjectVersion@ is your friend)
+             -> FilePath
+             -- ^ Path to the cabal package root directory (containing the
+             -- @cabal.sandbox.config@ file)
+             -> IO (Maybe FilePath)
+getSandboxPkgDb platform ghcVer projdir = do
+  mConf <-
+      T.traverse readFile =<< mightExist (projdir </> "cabal.sandbox.config")
+  return $ fixPkgDbVer <$> (extractSandboxDbDir =<< mConf)
+
+ where
+   fixPkgDbVer dir =
+       case takeFileName dir == ghcSandboxPkgDbDir platform ghcVer of
+         True -> dir
+         False -> takeDirectory dir </> ghcSandboxPkgDbDir platform ghcVer
+
+ghcSandboxPkgDbDir :: String -> Version -> String
+ghcSandboxPkgDbDir platform ghcVer =
+   platform ++ "-ghc-" ++ showVersion ghcVer ++ "-packages.conf.d"
+
+-- | Extract the sandbox package db directory from the cabal.sandbox.config
+-- file. Exception is thrown if the sandbox config file is broken.
+extractSandboxDbDir :: String -> Maybe FilePath
+extractSandboxDbDir conf = extractValue <$> parse conf
+  where
+    key = "package-db:"
+    keyLen = length key
+
+    parse = listToMaybe . filter (key `isPrefixOf`) . lines
+    extractValue = CabalHelper.Compiletime.Sandbox.dropWhileEnd isSpace . dropWhile isSpace . drop keyLen
+
+-- dropWhileEnd is not provided prior to base 4.5.0.0.
+dropWhileEnd :: (a -> Bool) -> [a] -> [a]
+dropWhileEnd p = foldr (\x xs -> if p x && null xs then [] else x : xs) []