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|
{-# 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.
#if defined(darwin_HOST_OS)
import Data.Word
import Foreign.C
import Foreign.Marshal.Alloc
import Foreign.Ptr
import Foreign.Storable
import System.Posix.Internals
#elif defined(linux_HOST_OS)
import Foreign.C
import Foreign.Marshal.Array
import System.Posix.Internals
#elif defined(mingw32_HOST_OS)
import Data.Word
import Foreign.C
import Foreign.Marshal.Array
import Foreign.Ptr
import System.Posix.Internals
#else
import Foreign.C
import Foreign.Marshal.Alloc
import Foreign.Ptr
import Foreign.Storable
import System.Posix.Internals
#endif
-- 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
#if defined(darwin_HOST_OS)
type UInt32 = Word32
foreign import ccall unsafe "mach-o/dyld.h _NSGetExecutablePath"
c__NSGetExecutablePath :: CString -> Ptr UInt32 -> IO CInt
-- | Returns the path of the main executable. The path may be a
-- symbolic link and not the real file.
--
-- See dyld(3)
_NSGetExecutablePath :: IO FilePath
_NSGetExecutablePath =
allocaBytes 1024 $ \ buf -> -- PATH_MAX is 1024 on OS X
alloca $ \ bufsize -> do
poke bufsize 1024
status <- c__NSGetExecutablePath buf bufsize
if status == 0
then peekFilePath buf
else do reqBufsize <- fromIntegral `fmap` peek bufsize
allocaBytes reqBufsize $ \ newBuf -> do
status2 <- c__NSGetExecutablePath newBuf bufsize
if status2 == 0
then peekFilePath newBuf
else error "_NSGetExecutablePath: buffer too small"
foreign import ccall unsafe "stdlib.h realpath"
c_realpath :: CString -> CString -> IO CString
-- | Resolves all symbolic links, extra \/ characters, and references
-- to \/.\/ and \/..\/. Returns an absolute pathname.
--
-- See realpath(3)
realpath :: FilePath -> IO FilePath
realpath path =
withFilePath path $ \ fileName ->
allocaBytes 1024 $ \ resolvedName -> do
_ <- throwErrnoIfNull "realpath" $ c_realpath fileName resolvedName
peekFilePath resolvedName
getExecutablePath = _NSGetExecutablePath >>= realpath
--------------------------------------------------------------------------------
-- Linux
#elif defined(linux_HOST_OS)
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
#elif defined(mingw32_HOST_OS)
# if defined(i386_HOST_ARCH)
## define WINDOWS_CCONV stdcall
# elif defined(x86_64_HOST_ARCH)
## define WINDOWS_CCONV ccall
# else
# error Unknown mingw32 arch
# endif
foreign import WINDOWS_CCONV unsafe "windows.h GetModuleFileNameW"
c_GetModuleFileName :: Ptr () -> CWString -> Word32 -> IO Word32
getExecutablePath = go 2048 -- plenty, PATH_MAX is 512 under Win32
where
go size = allocaArray (fromIntegral size) $ \ buf -> do
ret <- c_GetModuleFileName nullPtr buf size
case ret of
0 -> error "getExecutablePath: GetModuleFileNameW returned an error"
_ | ret < size -> peekFilePath buf
| otherwise -> go (size * 2)
--------------------------------------------------------------------------------
-- Fallback to argv[0]
#else
foreign import ccall unsafe "getFullProgArgv"
c_getFullProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()
getExecutablePath =
alloca $ \ p_argc ->
alloca $ \ p_argv -> do
c_getFullProgArgv p_argc p_argv
argc <- peek p_argc
if argc > 0
-- If argc > 0 then argv[0] is guaranteed by the standard
-- to be a pointer to a null-terminated string.
then peek p_argv >>= peek >>= peekFilePath
else error $ "getExecutablePath: " ++ msg
where msg = "no OS specific implementation and program name couldn't be " ++
"found in argv"
--------------------------------------------------------------------------------
#endif
|
