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|
-- |
-- Copyright: 2012 Joey Hess <id@joeyh.name>
-- License: LGPL 2.1 or higher
--
-- Derived from hsshellscript, originally written by
-- Volker Wysk <hsss@volker-wysk.de>
{-# LANGUAGE ForeignFunctionInterface, CPP #-}
module System.MountPoints (
Mntent(..),
getMounts,
getProcMounts,
) where
#include "libmounts.h"
import Control.Monad
import Control.Exception
import Data.Maybe
import Control.Applicative
import Foreign
import Foreign.C
import Prelude
-- | This is a stripped down mntent, containing only fields available
-- everywhere.
data Mntent = Mntent
{ mnt_fsname :: String -- ^ what's mounted
, mnt_dir :: FilePath -- ^ where it's mounted
, mnt_type :: String -- ^ what sort of filesystem is mounted
} deriving (Show, Eq, Ord)
-- | Get currently mounted filesystems.
--
-- This uses eiher getmntent or getmntinfo, depending on the OS.
getMounts :: IO [Mntent]
#ifndef linux_android_HOST_OS
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)
#else
getMounts = getProcMounts
#endif
#ifndef linux_android_HOST_OS
-- 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
#endif
-- | Read </proc/mounts> to get currently mounted filesystems.
--
-- This works on Linux and related systems, including Android.
-- Note that on Android, `getMounts` calls this function.
getProcMounts :: IO [Mntent]
getProcMounts = do
v <- try go :: IO (Either SomeException [Mntent])
return (either (const []) id v)
where
go = mapMaybe (parse . words) . lines <$> readFile "/proc/mounts"
parse (device:mountpoint:fstype:_rest) = Just $ Mntent
{ mnt_fsname = device
, mnt_dir = mountpoint
, mnt_type = fstype
}
parse _ = Nothing
|
