dist-install/build/System/Environment/ExecutablePath.hs

    {-# 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 ) where

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

    {-# LINE 32 "libraries/base/System/Environment/ExecutablePath.hsc" #-}
    import Foreign.C
    import Foreign.Marshal.Array
    import System.Posix.Internals

    {-# LINE 48 "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.
    --
    -- Note that for scripts and interactive sessions, this is the path to
    -- the interpreter (e.g. ghci.)
    --
    -- @since 4.6.0.0
    getExecutablePath :: IO FilePath

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

    {-# LINE 109 "libraries/base/System/Environment/ExecutablePath.hsc" #-}

    foreign import ccall unsafe "readlink"
        c_readlink :: CString -> CString -> CSize -> IO CInt

    -- | Reads the @FilePath@ pointed to by the symbolic link and returns
    -- it.
    --
    -- See readlink(2)
    readSymbolicLink :: FilePath -> IO FilePath
    readSymbolicLink file =
        allocaArray0 4096 $ \buf -> do
            withFilePath file $ \s -> do
                len <- throwErrnoPathIfMinus1 "readSymbolicLink" file $
                       c_readlink s buf 4096
                peekFilePathLen (buf,fromIntegral len)

    getExecutablePath = readSymbolicLink $ "/proc/self/exe"

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

    {-# LINE 176 "libraries/base/System/Environment/ExecutablePath.hsc" #-}