{-# 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 errorWithoutStackTrace "_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 -> errorWithoutStackTrace "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 errorWithoutStackTrace $ "getExecutablePath: " ++ msg where msg = "no OS specific implementation and program name couldn't be " ++ "found in argv" -------------------------------------------------------------------------------- #endif