{-# LINE 1 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
{-# LANGUAGE Safe #-}
{-# LANGUAGE CPP #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  System.Environment.ExecutablePath
-- Copyright   :  (c) The University of Glasgow 2001
-- License     :  BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer  :  libraries@haskell.org
-- Stability   :  provisional
-- Portability :  portable
--
-- Function to retrieve the absolute filepath of the current executable.
--
-- @since 4.6.0.0
-----------------------------------------------------------------------------

module System.Environment.ExecutablePath
  ( getExecutablePath
  , executablePath
  ) where

-- The imports are purposely kept completely disjoint to prevent edits
-- to one OS implementation from breaking another.


{-# LINE 42 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
import Control.Exception (catch, throw)
import Foreign.C
import Foreign.Marshal.Alloc
import Foreign.Marshal.Array
import Foreign.Ptr
import Foreign.Storable
import System.IO.Error (isDoesNotExistError)
import System.Posix.Internals



{-# LINE 68 "libraries/base/System/Environment/ExecutablePath.hsc" #-}

-- The exported function is defined outside any if-guard to make sure
-- every OS implements it with the same type.

-- | Returns the absolute pathname of the current executable,
-- or @argv[0]@ if the operating system does not provide a reliable
-- way query the current executable.
--
-- Note that for scripts and interactive sessions, this is the path to
-- the interpreter (e.g. ghci.)
--
-- Since base 4.11.0.0, 'getExecutablePath' resolves symlinks on Windows.
-- If an executable is launched through a symlink, 'getExecutablePath'
-- returns the absolute path of the original executable.
--
-- If the executable has been deleted, behaviour is ill-defined and
-- varies by operating system.  See 'executablePath' for a more
-- reliable way to query the current executable.
--
-- @since 4.6.0.0
getExecutablePath :: IO FilePath

-- | Get an action to query the absolute pathname of the current executable.
--
-- If the operating system provides a reliable way to determine the current
-- executable, return the query action, otherwise return @Nothing@.  The action
-- is defined on FreeBSD, Linux, MacOS and Windows.
--
-- Even where the query action is defined, there may be situations where no
-- result is available, e.g. if the executable file was deleted while the
-- program is running.  Therefore the result of the query action is a @Maybe
-- FilePath@.
--
-- Note that for scripts and interactive sessions, the result is the path to
-- the interpreter (e.g. ghci.)
--
-- @since 4.17.0.0
executablePath :: Maybe (IO (Maybe FilePath))


--------------------------------------------------------------------------------
-- Mac OS X


{-# LINE 193 "libraries/base/System/Environment/ExecutablePath.hsc" #-}

foreign import ccall unsafe "sysctl"
  c_sysctl
    :: Ptr CInt   -- MIB
    -> CUInt      -- MIB size
    -> Ptr CChar  -- old / current value buffer
    -> Ptr CSize  -- old / current value buffer size
    -> Ptr CChar  -- new value
    -> CSize      -- new value size
    -> IO CInt    -- result

getExecutablePath :: IO FilePath
getExecutablePath = do
  [CInt] -> (Int -> Ptr CInt -> IO FilePath) -> IO FilePath
forall a b. Storable a => [a] -> (Int -> Ptr a -> IO b) -> IO b
withArrayLen [CInt]
mib ((Int -> Ptr CInt -> IO FilePath) -> IO FilePath)
-> (Int -> Ptr CInt -> IO FilePath) -> IO FilePath
forall a b. (a -> b) -> a -> b
$ \Int
n Ptr CInt
mibPtr -> do
    let mibLen :: CUInt
mibLen = Int -> CUInt
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int
n
    (Ptr CSize -> IO FilePath) -> IO FilePath
forall a b. Storable a => (Ptr a -> IO b) -> IO b
alloca ((Ptr CSize -> IO FilePath) -> IO FilePath)
-> (Ptr CSize -> IO FilePath) -> IO FilePath
forall a b. (a -> b) -> a -> b
$ \Ptr CSize
bufSizePtr -> do
      CInt
status <- Ptr CInt
-> CUInt -> Ptr CChar -> Ptr CSize -> Ptr CChar -> CSize -> IO CInt
c_sysctl Ptr CInt
mibPtr CUInt
mibLen Ptr CChar
forall a. Ptr a
nullPtr Ptr CSize
bufSizePtr Ptr CChar
forall a. Ptr a
nullPtr CSize
0
      case CInt
status of
        CInt
0 -> do
          Int
reqBufSize <- CSize -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral (CSize -> Int) -> IO CSize -> IO Int
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Ptr CSize -> IO CSize
forall a. Storable a => Ptr a -> IO a
peek Ptr CSize
bufSizePtr
          Int -> (Ptr CChar -> IO FilePath) -> IO FilePath
forall a b. Int -> (Ptr a -> IO b) -> IO b
allocaBytes Int
reqBufSize ((Ptr CChar -> IO FilePath) -> IO FilePath)
-> (Ptr CChar -> IO FilePath) -> IO FilePath
forall a b. (a -> b) -> a -> b
$ \Ptr CChar
buf -> do
            CInt
newStatus <- Ptr CInt
-> CUInt -> Ptr CChar -> Ptr CSize -> Ptr CChar -> CSize -> IO CInt
c_sysctl Ptr CInt
mibPtr CUInt
mibLen Ptr CChar
buf Ptr CSize
bufSizePtr Ptr CChar
forall a. Ptr a
nullPtr CSize
0
            case CInt
newStatus of
              CInt
0 -> Ptr CChar -> IO FilePath
peekFilePath Ptr CChar
buf
              CInt
_ -> IO FilePath
forall {a}. IO a
barf
        CInt
_ -> IO FilePath
forall {a}. IO a
barf
  where
    barf :: IO a
barf = FilePath -> IO a
forall a. FilePath -> IO a
throwErrno FilePath
"getExecutablePath"
    mib :: [CInt]
mib =
      [ (CInt
1)
{-# LINE 222 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
      , (CInt
14)
{-# LINE 223 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
      , (CInt
12)
{-# LINE 224 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
      , -CInt
1   -- current process
      ]

executablePath :: Maybe (IO (Maybe FilePath))
executablePath = IO (Maybe FilePath) -> Maybe (IO (Maybe FilePath))
forall a. a -> Maybe a
Just ((FilePath -> Maybe FilePath) -> IO FilePath -> IO (Maybe FilePath)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap FilePath -> Maybe FilePath
forall a. a -> Maybe a
Just IO FilePath
getExecutablePath IO (Maybe FilePath)
-> (IOError -> IO (Maybe FilePath)) -> IO (Maybe FilePath)
forall e a. Exception e => IO a -> (e -> IO a) -> IO a
`catch` IOError -> IO (Maybe FilePath)
forall {f :: * -> *} {a}. Applicative f => IOError -> f (Maybe a)
f)
  where
  -- The sysctl fails with errno ENOENT when executable has been deleted;
  -- see https://gitlab.haskell.org/ghc/ghc/-/issues/12377#note_321346.
  f :: IOError -> f (Maybe a)
f IOError
e | IOError -> Bool
isDoesNotExistError IOError
e = Maybe a -> f (Maybe a)
forall (f :: * -> *) a. Applicative f => a -> f a
pure Maybe a
forall a. Maybe a
Nothing

  -- As far as I know, ENOENT is the only kind of failure that should be
  -- expected and handled.  Re-throw other errors.
      | Bool
otherwise             = IOError -> f (Maybe a)
forall a e. Exception e => e -> a
throw IOError
e


--------------------------------------------------------------------------------
-- Windows


{-# LINE 362 "libraries/base/System/Environment/ExecutablePath.hsc" #-}