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{- Interface to mtab (and fstab)
-
- Derived from hsshellscript, originally written by
- Volker Wysk <hsss@volker-wysk.de>
-
- Modified to support BSD, Mac OS X, and Android by
- Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU LGPL version 2.1 or higher.
-}
{-# LANGUAGE ForeignFunctionInterface #-}
module Utility.Mounts (
Mntent(..),
getMounts
) where
#ifndef __ANDROID__
import Control.Monad
import Foreign
import Foreign.C
#include "libmounts.h"
#else
import Utility.Exception
import Data.Maybe
import Control.Applicative
#endif
{- This is a stripped down mntent, containing only
- fields available everywhere. -}
data Mntent = Mntent
{ mnt_fsname :: String
, mnt_dir :: FilePath
, mnt_type :: String
} deriving (Read, Show, Eq, Ord)
#ifndef __ANDROID__
getMounts :: IO [Mntent]
getMounts = do
h <- c_mounts_start
when (h == nullPtr) $
throwErrno "getMounts"
mntent <- getmntent h []
_ <- c_mounts_end h
return mntent
where
getmntent h c = do
ptr <- c_mounts_next h
if (ptr == nullPtr)
then return $ reverse c
else do
mnt_fsname_str <- #{peek struct mntent, mnt_fsname} ptr >>= peekCString
mnt_dir_str <- #{peek struct mntent, mnt_dir} ptr >>= peekCString
mnt_type_str <- #{peek struct mntent, mnt_type} ptr >>= peekCString
let ent = Mntent
{ mnt_fsname = mnt_fsname_str
, mnt_dir = mnt_dir_str
, mnt_type = mnt_type_str
}
getmntent h (ent:c)
{- Using unsafe imports because the C functions are belived to never block.
- Note that getmntinfo is called with MNT_NOWAIT to avoid possibly blocking;
- while getmntent only accesses a file in /etc (or /proc) that should not
- block. -}
foreign import ccall unsafe "libmounts.h mounts_start" c_mounts_start
:: IO (Ptr ())
foreign import ccall unsafe "libmounts.h mounts_next" c_mounts_next
:: Ptr () -> IO (Ptr ())
foreign import ccall unsafe "libmounts.h mounts_end" c_mounts_end
:: Ptr () -> IO CInt
#else
{- Android does not support getmntent (well, it's a no-op stub in Bionic).
-
- But, the linux kernel's /proc/mounts is available to be parsed.
-}
getMounts :: IO [Mntent]
getMounts = catchDefaultIO [] $
mapMaybe (parse . words) . lines <$> readFile "/proc/mounts"
where
parse (device:mountpoint:fstype:_rest) = Just $ Mntent
{ mnt_fsname = device
, mnt_dir = mountpoint
, mnt_type = fstype
}
parse _ = Nothing
#endif
|
