    {-# LINE 1 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}
    {-# LANGUAGE CApiFFI #-}
    {-# LANGUAGE Trustworthy #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.Env.ByteString
    -- Copyright   :  (c) The University of Glasgow 2002
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  provisional
    -- Portability :  non-portable (requires POSIX)
    --
    -- POSIX environment support
    --
    -----------------------------------------------------------------------------

    module System.Posix.Env.ByteString (
           -- * Environment Variables
            getEnv
            , getEnvDefault
            , getEnvironmentPrim
            , getEnvironment
            , setEnvironment
            , putEnv
            , setEnv
            , unsetEnv
            , clearEnv

           -- * Program arguments
           , getArgs
    ) where

    import Control.Monad
    import Foreign
    import Foreign.C
    import Data.Maybe       ( fromMaybe )

    import System.Posix.Env ( clearEnv )
    import qualified Data.ByteString as B
    import qualified Data.ByteString.Char8 as BC
    import Data.ByteString (ByteString)
    import Data.ByteString.Internal (ByteString (PS))

    import qualified System.Posix.Env.Internal as Internal

    -- |'getEnv' looks up a variable in the environment.

    getEnv ::
      ByteString            {- ^ variable name  -} ->
      IO (Maybe ByteString) {- ^ variable value -}
    getEnv :: ByteString -> IO (Maybe ByteString)
    getEnv ByteString
    name = do
      litstring <- ByteString -> (CString -> IO CString) -> IO CString
    forall a. ByteString -> (CString -> IO a) -> IO a
    B.useAsCString ByteString
    name CString -> IO CString
    c_getenv
      if litstring /= nullPtr
         then Just <$> B.packCString litstring
         else return Nothing

    -- |'getEnvDefault' is a wrapper around 'getEnv' where the
    -- programmer can specify a fallback as the second argument, which will be
    -- used if the variable is not found in the environment.

    getEnvDefault ::
      ByteString    {- ^ variable name                    -} ->
      ByteString    {- ^ fallback value                   -} ->
      IO ByteString {- ^ variable value or fallback value -}
    getEnvDefault :: ByteString -> ByteString -> IO ByteString
    getEnvDefault ByteString
    name ByteString
    fallback = ByteString -> Maybe ByteString -> ByteString
    forall a. a -> Maybe a -> a
    fromMaybe ByteString
    fallback (Maybe ByteString -> ByteString)
    -> IO (Maybe ByteString) -> IO ByteString
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> ByteString -> IO (Maybe ByteString)
    getEnv ByteString
    name

    foreign import ccall unsafe "getenv"
       c_getenv :: CString -> IO CString

    getEnvironmentPrim :: IO [ByteString]
    getEnvironmentPrim :: IO [ByteString]
    getEnvironmentPrim = IO [CString]
    Internal.getEnvironmentPrim IO [CString] -> ([CString] -> IO [ByteString]) -> IO [ByteString]
    forall a b. IO a -> (a -> IO b) -> IO b
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= (CString -> IO ByteString) -> [CString] -> IO [ByteString]
    forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
    mapM CString -> IO ByteString
    B.packCString

    -- |'getEnvironment' retrieves the entire environment as a
    -- list of @(key,value)@ pairs.

    getEnvironment :: IO [(ByteString,ByteString)] {- ^ @[(key,value)]@ -}
    getEnvironment :: IO [(ByteString, ByteString)]
    getEnvironment = do
      env <- IO [ByteString]
    getEnvironmentPrim
      return $ map (dropEq.(BC.break ((==) '='))) env
     where
       dropEq :: (ByteString, ByteString) -> (ByteString, ByteString)
    dropEq (ByteString
    x,ByteString
    y)
          | ByteString -> Char
    BC.head ByteString
    y Char -> Char -> Bool
    forall a. Eq a => a -> a -> Bool
    == Char
    '=' = (ByteString
    x,HasCallStack => ByteString -> ByteString
    ByteString -> ByteString
    B.tail ByteString
    y)
          | Bool
    otherwise       = [Char] -> (ByteString, ByteString)
    forall a. HasCallStack => [Char] -> a
    error ([Char] -> (ByteString, ByteString))
    -> [Char] -> (ByteString, ByteString)
    forall a b. (a -> b) -> a -> b
    $ [Char]
    "getEnvironment: insane variable " [Char] -> [Char] -> [Char]
    forall a. [a] -> [a] -> [a]
    ++ ByteString -> [Char]
    BC.unpack ByteString
    x

    -- |'setEnvironment' resets the entire environment to the given list of
    -- @(key,value)@ pairs.
    --
    -- @since 2.8.0.0
    setEnvironment ::
      [(ByteString,ByteString)] {- ^ @[(key,value)]@ -} ->
      IO ()
    setEnvironment :: [(ByteString, ByteString)] -> IO ()
    setEnvironment [(ByteString, ByteString)]
    env = do
      IO ()
    clearEnv
      [(ByteString, ByteString)]
    -> ((ByteString, ByteString) -> IO ()) -> IO ()
    forall (t :: * -> *) (m :: * -> *) a b.
    (Foldable t, Monad m) =>
    t a -> (a -> m b) -> m ()
    forM_ [(ByteString, ByteString)]
    env (((ByteString, ByteString) -> IO ()) -> IO ())
    -> ((ByteString, ByteString) -> IO ()) -> IO ()
    forall a b. (a -> b) -> a -> b
    $ \(ByteString
    key,ByteString
    value) ->
        ByteString -> ByteString -> Bool -> IO ()
    setEnv ByteString
    key ByteString
    value Bool
    True {-overwrite-}

    -- |The 'unsetEnv' function deletes all instances of the variable name
    -- from the environment.

    unsetEnv :: ByteString {- ^ variable name -} -> IO ()

    {-# LINE 105 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}

    unsetEnv :: ByteString -> IO ()
    {-# LINE 106 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}
    unsetEnv name = B.useAsCString name $ \ s ->
      throwErrnoIfMinus1_ "unsetenv" (c_unsetenv s)

    -- POSIX.1-2001 compliant unsetenv(3)
    foreign import capi unsafe "HsUnix.h unsetenv"
       c_unsetenv :: CString -> IO CInt

    {-# LINE 119 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}

    {-# LINE 122 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}

    -- |'putEnv' function takes an argument of the form @name=value@
    -- and is equivalent to @setEnv(key,value,True{-overwrite-})@.

    putEnv :: ByteString {- ^ "key=value" -} -> IO ()
    putEnv :: ByteString -> IO ()
    putEnv (PS ForeignPtr Word8
    fp Int
    o Int
    l) = ForeignPtr Word8 -> (Ptr Word8 -> IO ()) -> IO ()
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    withForeignPtr ForeignPtr Word8
    fp ((Ptr Word8 -> IO ()) -> IO ()) -> (Ptr Word8 -> IO ()) -> IO ()
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    p -> do
      -- https://pubs.opengroup.org/onlinepubs/009696899/functions/putenv.html
      --
      -- "the string pointed to by string shall become part of the environment,
      -- so altering the string shall change the environment. The space used by
      -- string is no longer used once a new string which defines name is passed to putenv()."
      --
      -- hence we must not free the buffer
      buf <- Int -> IO (Ptr Any)
    forall a. Int -> IO (Ptr a)
    mallocBytes (Int
    lInt -> Int -> Int
    forall a. Num a => a -> a -> a
    +Int
    1)
      copyBytes buf (p `plusPtr` o) l
      pokeByteOff buf l (0::Word8)
      throwErrnoIfMinus1_ "putenv" (c_putenv (castPtr buf))

    foreign import ccall unsafe "putenv"
       c_putenv :: CString -> IO CInt

    {- |The 'setEnv' function inserts or resets the environment variable name in
         the current environment list.  If the variable @name@ does not exist in the
         list, it is inserted with the given value.  If the variable does exist,
         the argument @overwrite@ is tested; if @overwrite@ is @False@, the variable is
         not reset, otherwise it is reset to the given value.
    -}

    setEnv ::
      ByteString {- ^ variable name  -} ->
      ByteString {- ^ variable value -} ->
      Bool       {- ^ overwrite      -} ->
      IO ()

    {-# LINE 156 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}
    setEnv key value ovrwrt = do
      B.useAsCString key $ \ keyP ->
        B.useAsCString value $ \ valueP ->
          throwErrnoIfMinus1_ "setenv" $
            c_setenv keyP valueP (fromIntegral (fromEnum ovrwrt))

    foreign import ccall unsafe "setenv"
       c_setenv :: CString -> CString -> CInt -> IO CInt

    {-# LINE 172 "libraries/unix/System/Posix/Env/ByteString.hsc" #-}

    -- | Computation 'getArgs' returns a list of the program's command
    -- line arguments (not including the program name), as 'ByteString's.
    --
    -- Unlike 'System.Environment.getArgs', this function does no Unicode
    -- decoding of the arguments; you get the exact bytes that were passed
    -- to the program by the OS.  To interpret the arguments as text, some
    -- Unicode decoding should be applied.
    --
    getArgs :: IO [ByteString]
    getArgs :: IO [ByteString]
    getArgs =
      (Ptr CInt -> IO [ByteString]) -> IO [ByteString]
    forall a b. Storable a => (Ptr a -> IO b) -> IO b
    alloca ((Ptr CInt -> IO [ByteString]) -> IO [ByteString])
    -> (Ptr CInt -> IO [ByteString]) -> IO [ByteString]
    forall a b. (a -> b) -> a -> b
    $ \ Ptr CInt
    p_argc ->
      (Ptr (Ptr CString) -> IO [ByteString]) -> IO [ByteString]
    forall a b. Storable a => (Ptr a -> IO b) -> IO b
    alloca ((Ptr (Ptr CString) -> IO [ByteString]) -> IO [ByteString])
    -> (Ptr (Ptr CString) -> IO [ByteString]) -> IO [ByteString]
    forall a b. (a -> b) -> a -> b
    $ \ Ptr (Ptr CString)
    p_argv -> do
       Ptr CInt -> Ptr (Ptr CString) -> IO ()
    getProgArgv Ptr CInt
    p_argc Ptr (Ptr CString)
    p_argv
       p    <- CInt -> Int
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral (CInt -> Int) -> IO CInt -> IO Int
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> Ptr CInt -> IO CInt
    forall a. Storable a => Ptr a -> IO a
    peek Ptr CInt
    p_argc
       argv <- peek p_argv
       peekArray (p - 1) (advancePtr argv 1) >>= mapM B.packCString

    foreign import ccall unsafe "getProgArgv"
      getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()