{-# LANGUAGE Safe #-} {-# LANGUAGE CPP #-} ----------------------------------------------------------------------------- -- | -- Module : System.Environment -- Copyright : (c) The University of Glasgow 2001 -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : provisional -- Portability : portable -- -- Miscellaneous information about the system environment. -- ----------------------------------------------------------------------------- module System.Environment ( getArgs, getProgName, executablePath, getExecutablePath, getEnv, lookupEnv, setEnv, unsetEnv, withArgs, withProgName, getEnvironment, ) where import Foreign import Foreign.C import System.IO.Error (mkIOError) import Control.Exception.Base (bracket_, throwIO) #if defined(mingw32_HOST_OS) import Control.Exception.Base (bracket) #endif -- import GHC.IO import GHC.IO.Exception import qualified GHC.Foreign as GHC import Control.Monad #if defined(mingw32_HOST_OS) import GHC.IO.Encoding (argvEncoding) import GHC.Windows #else import GHC.IO.Encoding (getFileSystemEncoding, argvEncoding) import System.Posix.Internals (withFilePath) #endif import System.Environment.ExecutablePath #if 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 #endif #include "HsBaseConfig.h" -- --------------------------------------------------------------------------- -- getArgs, getProgName, getEnv -- | Computation 'getArgs' returns a list of the program's command -- line arguments (not including the program name). getArgs :: IO [String] getArgs = alloca $ \ p_argc -> alloca $ \ p_argv -> do getProgArgv p_argc p_argv p <- fromIntegral `liftM` peek p_argc argv <- peek p_argv enc <- argvEncoding peekArray (p - 1) (advancePtr argv 1) >>= mapM (GHC.peekCString enc) foreign import ccall unsafe "getProgArgv" getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO () {-| Computation 'getProgName' returns the name of the program as it was invoked. However, this is hard-to-impossible to implement on some non-Unix OSes, so instead, for maximum portability, we just return the leafname of the program as invoked. Even then there are some differences between platforms: on Windows, for example, a program invoked as foo is probably really @FOO.EXE@, and that is what 'getProgName' will return. -} getProgName :: IO String -- Ignore the arguments to hs_init on Windows for the sake of Unicode compat getProgName = alloca $ \ p_argc -> alloca $ \ p_argv -> do getProgArgv p_argc p_argv argv <- peek p_argv unpackProgName argv unpackProgName :: Ptr (Ptr CChar) -> IO String -- argv[0] unpackProgName argv = do enc <- argvEncoding s <- peekElemOff argv 0 >>= GHC.peekCString enc return (basename s) basename :: FilePath -> FilePath basename f = go f f where go acc [] = acc go acc (x:xs) | isPathSeparator x = go xs xs | otherwise = go acc xs isPathSeparator :: Char -> Bool isPathSeparator '/' = True #if defined(mingw32_HOST_OS) isPathSeparator '\\' = True #endif isPathSeparator _ = False -- | Computation 'getEnv' @var@ returns the value -- of the environment variable @var@. For the inverse, the -- `System.Environment.setEnv` function can be used. -- -- This computation may fail with: -- -- * 'System.IO.Error.isDoesNotExistError' if the environment variable -- does not exist. getEnv :: String -> IO String getEnv name = lookupEnv name >>= maybe handleError return where #if defined(mingw32_HOST_OS) handleError = do err <- c_GetLastError if err == eRROR_ENVVAR_NOT_FOUND then ioe_missingEnvVar name else throwGetLastError "getEnv" eRROR_ENVVAR_NOT_FOUND :: DWORD eRROR_ENVVAR_NOT_FOUND = 203 foreign import WINDOWS_CCONV unsafe "windows.h GetLastError" c_GetLastError:: IO DWORD #else handleError = ioe_missingEnvVar name #endif -- | Return the value of the environment variable @var@, or @Nothing@ if -- there is no such value. -- -- For POSIX users, this is equivalent to 'System.Posix.Env.getEnv'. -- -- @since 4.6.0.0 lookupEnv :: String -> IO (Maybe String) #if defined(mingw32_HOST_OS) lookupEnv name = withCWString name $ \s -> try_size s 256 where try_size s size = allocaArray (fromIntegral size) $ \p_value -> do res <- c_GetEnvironmentVariable s p_value size case res of 0 -> return Nothing _ | res > size -> try_size s res -- Rare: size increased between calls to GetEnvironmentVariable | otherwise -> peekCWString p_value >>= return . Just foreign import WINDOWS_CCONV unsafe "windows.h GetEnvironmentVariableW" c_GetEnvironmentVariable :: LPWSTR -> LPWSTR -> DWORD -> IO DWORD #else lookupEnv name = withCString name $ \s -> do litstring <- c_getenv s if litstring /= nullPtr then do enc <- getFileSystemEncoding result <- GHC.peekCString enc litstring return $ Just result else return Nothing foreign import ccall unsafe "getenv" c_getenv :: CString -> IO (Ptr CChar) #endif ioe_missingEnvVar :: String -> IO a ioe_missingEnvVar name = ioException (IOError Nothing NoSuchThing "getEnv" "no environment variable" Nothing (Just name)) -- | @setEnv name value@ sets the specified environment variable to @value@. -- -- Early versions of this function operated under the mistaken belief that -- setting an environment variable to the /empty string/ on Windows removes -- that environment variable from the environment. For the sake of -- compatibility, it adopted that behavior on POSIX. In particular -- -- @ -- setEnv name \"\" -- @ -- -- has the same effect as -- -- @ -- `unsetEnv` name -- @ -- -- If you'd like to be able to set environment variables to blank strings, -- use `System.Environment.Blank.setEnv`. -- -- Throws `Control.Exception.IOException` if @name@ is the empty string or -- contains an equals sign. -- -- @since 4.7.0.0 setEnv :: String -> String -> IO () setEnv key_ value_ | null key = throwIO (mkIOError InvalidArgument "setEnv" Nothing Nothing) | '=' `elem` key = throwIO (mkIOError InvalidArgument "setEnv" Nothing Nothing) | null value = unsetEnv key | otherwise = setEnv_ key value where key = takeWhile (/= '\NUL') key_ value = takeWhile (/= '\NUL') value_ setEnv_ :: String -> String -> IO () #if defined(mingw32_HOST_OS) setEnv_ key value = withCWString key $ \k -> withCWString value $ \v -> do success <- c_SetEnvironmentVariable k v unless success (throwGetLastError "setEnv") foreign import WINDOWS_CCONV unsafe "windows.h SetEnvironmentVariableW" c_SetEnvironmentVariable :: LPTSTR -> LPTSTR -> IO Bool #else -- NOTE: The 'setenv()' function is not available on all systems, hence we use -- 'putenv()'. This leaks memory, but so do common implementations of -- 'setenv()' (AFAIK). setEnv_ k v = putEnv (k ++ "=" ++ v) putEnv :: String -> IO () putEnv keyvalue = do s <- getFileSystemEncoding >>= (`GHC.newCString` keyvalue) -- IMPORTANT: Do not free `s` after calling putenv! -- -- According to SUSv2, the string passed to putenv becomes part of the -- environment. throwErrnoIf_ (/= 0) "putenv" (c_putenv s) foreign import ccall unsafe "putenv" c_putenv :: CString -> IO CInt #endif -- | @unsetEnv name@ removes the specified environment variable from the -- environment of the current process. -- -- Throws `Control.Exception.IOException` if @name@ is the empty string or -- contains an equals sign. -- -- @since 4.7.0.0 unsetEnv :: String -> IO () #if defined(mingw32_HOST_OS) unsetEnv key = withCWString key $ \k -> do success <- c_SetEnvironmentVariable k nullPtr unless success $ do -- We consider unsetting an environment variable that does not exist not as -- an error, hence we ignore eRROR_ENVVAR_NOT_FOUND. err <- c_GetLastError unless (err == eRROR_ENVVAR_NOT_FOUND) $ do throwGetLastError "unsetEnv" #else #if defined(HAVE_UNSETENV) unsetEnv key = withFilePath key (throwErrnoIf_ (/= 0) "unsetEnv" . c_unsetenv) foreign import ccall unsafe "__hsbase_unsetenv" c_unsetenv :: CString -> IO CInt #else unsetEnv key = setEnv_ key "" #endif #endif {-| 'withArgs' @args act@ - while executing action @act@, have 'getArgs' return @args@. -} withArgs :: [String] -> IO a -> IO a withArgs xs act = do p <- System.Environment.getProgName withArgv (p:xs) act {-| 'withProgName' @name act@ - while executing action @act@, have 'getProgName' return @name@. -} withProgName :: String -> IO a -> IO a withProgName nm act = do xs <- System.Environment.getArgs withArgv (nm:xs) act -- Worker routine which marshals and replaces an argv vector for -- the duration of an action. withArgv :: [String] -> IO a -> IO a withArgv = withProgArgv withProgArgv :: [String] -> IO a -> IO a withProgArgv new_args act = do pName <- System.Environment.getProgName existing_args <- System.Environment.getArgs bracket_ (setProgArgv new_args) (setProgArgv (pName:existing_args)) act setProgArgv :: [String] -> IO () setProgArgv argv = do enc <- argvEncoding GHC.withCStringsLen enc argv $ \len css -> c_setProgArgv (fromIntegral len) css -- setProgArgv copies the arguments foreign import ccall unsafe "setProgArgv" c_setProgArgv :: CInt -> Ptr CString -> IO () -- |'getEnvironment' retrieves the entire environment as a -- list of @(key,value)@ pairs. -- -- If an environment entry does not contain an @\'=\'@ character, -- the @key@ is the whole entry and the @value@ is the empty string. getEnvironment :: IO [(String, String)] #if defined(mingw32_HOST_OS) getEnvironment = bracket c_GetEnvironmentStrings c_FreeEnvironmentStrings $ \pBlock -> if pBlock == nullPtr then return [] else go pBlock where go pBlock = do -- The block is terminated by a null byte where there -- should be an environment variable of the form X=Y c <- peek pBlock if c == 0 then return [] else do -- Seek the next pair (or terminating null): pBlock' <- seekNull pBlock False -- We now know the length in bytes, but ignore it when -- getting the actual String: str <- peekCWString pBlock fmap (divvy str :) $ go pBlock' -- Returns pointer to the byte *after* the next null seekNull pBlock done = do let pBlock' = pBlock `plusPtr` sizeOf (undefined :: CWchar) if done then return pBlock' else do c <- peek pBlock' seekNull pBlock' (c == (0 :: Word8 )) foreign import WINDOWS_CCONV unsafe "windows.h GetEnvironmentStringsW" c_GetEnvironmentStrings :: IO (Ptr CWchar) foreign import WINDOWS_CCONV unsafe "windows.h FreeEnvironmentStringsW" c_FreeEnvironmentStrings :: Ptr CWchar -> IO Bool #else getEnvironment = do pBlock <- getEnvBlock if pBlock == nullPtr then return [] else do enc <- getFileSystemEncoding stuff <- peekArray0 nullPtr pBlock >>= mapM (GHC.peekCString enc) return (map divvy stuff) foreign import ccall unsafe "__hscore_environ" getEnvBlock :: IO (Ptr CString) #endif divvy :: String -> (String, String) divvy str = case break (=='=') str of (xs,[]) -> (xs,[]) -- don't barf (like Posix.getEnvironment) (name,_:value) -> (name,value)