base-4.12.0.0: 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.
#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 Control.Exception
import Data.List
import Data.Word
import Foreign.C
import Foreign.Marshal.Array
import Foreign.Ptr
#include <windows.h>
#include <stdint.h>
#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 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.
--
-- @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
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 -> do
path <- peekCWString buf
real <- getFinalPath path
exists <- withCWString real c_pathFileExists
if exists
then return real
else fail path
| otherwise -> go (size * 2)
-- | Returns the final path of the given path. If the given
-- path is a symbolic link, the returned value is the
-- path the (possibly chain of) symbolic link(s) points to.
-- Otherwise, the original path is returned, even when the filepath
-- is incorrect.
--
-- Adapted from:
-- https://msdn.microsoft.com/en-us/library/windows/desktop/aa364962.aspx
getFinalPath :: FilePath -> IO FilePath
getFinalPath path = withCWString path $ \s ->
bracket (createFile s) c_closeHandle $ \h -> do
let invalid = h == wordPtrToPtr (#const (intptr_t)INVALID_HANDLE_VALUE)
if invalid then pure path else go h bufSize
where go h sz = allocaArray (fromIntegral sz) $ \outPath -> do
ret <- c_getFinalPathHandle h outPath sz (#const FILE_NAME_OPENED)
if ret < sz
then sanitize . rejectUNCPath <$> peekCWString outPath
else go h (2 * sz)
sanitize s
| "\\\\?\\" `isPrefixOf` s = drop 4 s
| otherwise = s
-- see https://ghc.haskell.org/trac/ghc/ticket/14460
rejectUNCPath s
| "\\\\?\\UNC\\" `isPrefixOf` s = path
| otherwise = s
-- the initial size of the buffer in which we store the
-- final path; if this is not enough, we try with a buffer of
-- size 2^k * bufSize, for k = 1, 2, 3, ... until the buffer
-- is large enough.
bufSize = 1024
foreign import WINDOWS_CCONV unsafe "windows.h GetModuleFileNameW"
c_GetModuleFileName :: Ptr () -> CWString -> Word32 -> IO Word32
foreign import WINDOWS_CCONV unsafe "windows.h PathFileExistsW"
c_pathFileExists :: CWString -> IO Bool
foreign import WINDOWS_CCONV unsafe "windows.h CreateFileW"
c_createFile :: CWString
-> Word32
-> Word32
-> Ptr ()
-> Word32
-> Word32
-> Ptr ()
-> IO (Ptr ())
createFile :: CWString -> IO (Ptr ())
createFile file =
c_createFile file (#const GENERIC_READ)
(#const FILE_SHARE_READ)
nullPtr
(#const OPEN_EXISTING)
(#const FILE_ATTRIBUTE_NORMAL)
nullPtr
foreign import WINDOWS_CCONV unsafe "windows.h CloseHandle"
c_closeHandle :: Ptr () -> IO Bool
foreign import WINDOWS_CCONV unsafe "windows.h GetFinalPathNameByHandleW"
c_getFinalPathHandle :: Ptr () -> CWString -> Word32 -> Word32 -> IO Word32
--------------------------------------------------------------------------------
-- 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