finally really add back custom-setup stanza

Fourth or fifth try at this and finally found a way to make it work.

Absurd amount of busy-work forced on me by change in cabal's behavior.
Split up Utility modules that need posix stuff out of ones used by
Setup. Various other hacks around inability for Setup to use anything
that ifdefs a use of unix.

Probably lost a full day of my life to this.
This is how build systems make their users hate them. Just saying.

1 files changed, 40 insertions, 0 deletions

diff --git a/Utility/Path/Max.hs b/Utility/Path/Max.hs
new file mode 100644
index 000000000..4a810e591
--- /dev/null
+++ b/Utility/Path/Max.hs
@@ -0,0 +1,40 @@
+{- path manipulation
+ -
+ - Copyright 2010-2014 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# LANGUAGE CPP #-}
+{-# OPTIONS_GHC -fno-warn-tabs #-}
+
+module Utility.Path.Max where
+
+import System.FilePath
+import Data.List
+import Control.Applicative
+import Prelude
+
+#ifndef mingw32_HOST_OS
+import Utility.Exception
+import System.Posix.Files
+#endif
+
+{- Maximum size to use for a file in a specified directory.
+ -
+ - Many systems have a 255 byte limit to the name of a file, 
+ - so that's taken as the max if the system has a larger limit, or has no
+ - limit.
+ -}
+fileNameLengthLimit :: FilePath -> IO Int
+#ifdef mingw32_HOST_OS
+fileNameLengthLimit _ = return 255
+#else
+fileNameLengthLimit dir = do
+	-- getPathVar can fail due to statfs(2) overflow
+	l <- catchDefaultIO 0 $
+		fromIntegral <$> getPathVar dir FileNameLimit
+	if l <= 0
+		then return 255
+		else return $ minimum [l, 255]
+#endif