src/Darcs/CheckFileSystem.lhs

   1 %  Copyright (C) 2004 David Roundy
   2 %
   3 %  This program is free software; you can redistribute it and/or modify
   4 %  it under the terms of the GNU General Public License as published by
   5 %  the Free Software Foundation; either version 2, or (at your option)
   6 %  any later version.
   7 %
   8 %  This program is distributed in the hope that it will be useful,
   9 %  but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 %  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 %  GNU General Public License for more details.
  12 %
  13 %  You should have received a copy of the GNU General Public License
  14 %  along with this program; see the file COPYING.  If not, write to
  15 %  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  16 %  Boston, MA 02110-1301, USA.
  17
  18
  19 \begin{code}
  20 module Darcs.CheckFileSystem ( can_I_use_mmap ) where
  21
  22 import System.Directory ( removeFile, removeDirectory, setCurrentDirectory,
  23                           createDirectory,
  24                         )
  25 import Control.Exception ( block )
  26
  27 import Darcs.Utils ( withCurrentDirectory )
  28 import Darcs.Lock ( withOpenTemp )
  29
  30 -- Beware that the below test will return true in any directory where we
  31 -- don't have write permission.  This is risky, but means we'll do the
  32 -- right thing in the common case where we're dealing with posix
  33 -- filesystems and directories in which we don't have permission to write.
  34
  35 can_I_remove_open_files :: IO Bool
  36 can_I_remove_open_files = block $
  37    (withOpenTemp $ \ (_,f) ->
  38        (do { removeFile f; return True}) `catch` \_ -> return False)
  39    `catch` \_ -> return True
  40
  41 can_I_remove_directories_holding_open_files :: IO Bool
  42 can_I_remove_directories_holding_open_files = block $
  43    (do createDirectory "darcs_testing_for_nfs"
  44        okay <- (withCurrentDirectory "darcs_testing_for_nfs" $
  45                 do withOpenTemp $ \ (_,f) ->
  46                        (do removeFile f
  47                            setCurrentDirectory ".."
  48                            removeDirectory "darcs_testing_for_nfs"
  49                            return True
  50                        ) `catch` \_ -> return False
  51                ) `catch` \_ -> return True
  52        removeDirectory "darcs_testing_for_nfs" `catch` \_ -> return ()
  53        return okay
  54    ) `catch` \_ -> return True
  55
  56 can_I_use_mmap :: IO Bool
  57 can_I_use_mmap = do a <- can_I_remove_open_files
  58                     if a then can_I_remove_directories_holding_open_files
  59                          else return False
  60 \end{code}
  61
  62