-{-# OPTIONS -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
-----------------------------------------------------------------------------
---
+-- |
-- Module : System.IO.Error
-- Copyright : (c) The University of Glasgow 2001
--- License : BSD-style (see the file libraries/core/LICENSE)
+-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
--- $Id: Error.hs,v 1.3 2002/03/27 17:55:26 simonmar Exp $
---
-- Standard IO Errors.
--
-----------------------------------------------------------------------------
module System.IO.Error (
- IOError, -- abstract
- IOErrorType, -- abstract
- ioError, -- :: IOError -> IO a
- userError, -- :: String -> IOError
+ -- * I\/O errors
+ IOError, -- = IOException
+
+ userError, -- :: String -> IOError
- mkIOError, -- :: IOErrorType -> String -> Maybe Handle
- -- -> Maybe FilePath -> IOError
+ mkIOError, -- :: IOErrorType -> String -> Maybe Handle
+ -- -> Maybe FilePath -> IOError
- alreadyExistsErrorType, -- :: IOErrorType
+ annotateIOError, -- :: IOError -> String -> Maybe Handle
+ -- -> Maybe FilePath -> IOError
+
+ -- ** Classifying I\/O errors
+ isAlreadyExistsError, -- :: IOError -> Bool
+ isDoesNotExistError,
+ isAlreadyInUseError,
+ isFullError,
+ isEOFError,
+ isIllegalOperation,
+ isPermissionError,
+ isUserError,
+
+ -- ** Attributes of I\/O errors
+ ioeGetErrorType, -- :: IOError -> IOErrorType
+ ioeGetLocation, -- :: IOError -> String
+ ioeGetErrorString, -- :: IOError -> String
+ ioeGetHandle, -- :: IOError -> Maybe Handle
+ ioeGetFileName, -- :: IOError -> Maybe FilePath
+
+ ioeSetErrorType, -- :: IOError -> IOErrorType -> IOError
+ ioeSetErrorString, -- :: IOError -> String -> IOError
+ ioeSetLocation, -- :: IOError -> String -> IOError
+ ioeSetHandle, -- :: IOError -> Handle -> IOError
+ ioeSetFileName, -- :: IOError -> FilePath -> IOError
+
+ -- * Types of I\/O error
+ IOErrorType, -- abstract
+
+ alreadyExistsErrorType, -- :: IOErrorType
doesNotExistErrorType,
alreadyInUseErrorType,
fullErrorType,
permissionErrorType,
userErrorType,
- isAlreadyExistsErrorType, -- :: IOErrorType -> Bool
+ -- ** 'IOErrorType' predicates
+ isAlreadyExistsErrorType, -- :: IOErrorType -> Bool
isDoesNotExistErrorType,
isAlreadyInUseErrorType,
isFullErrorType,
isPermissionErrorType,
isUserErrorType,
- isAlreadyExistsError, -- :: IOError -> Bool
- isDoesNotExistError,
- isAlreadyInUseError,
- isFullError,
- isEOFError,
- isIllegalOperation,
- isPermissionError,
- isUserError,
+ -- * Throwing and catching I\/O errors
- ioeGetErrorType, -- :: IOError -> IOErrorType
- ioeGetErrorString, -- :: IOError -> String
- ioeGetHandle, -- :: IOError -> Maybe Handle
- ioeGetFileName, -- :: IOError -> Maybe FilePath
+ ioError, -- :: IOError -> IO a
+ catch, -- :: IO a -> (IOError -> IO a) -> IO a
+ try, -- :: IO a -> IO (Either IOError a)
+
+ modifyIOError, -- :: (IOError -> IOError) -> IO a -> IO a
) where
+#ifndef __HUGS__
+import qualified Control.Exception.Base as New (catch)
+#endif
+
+#ifndef __HUGS__
+import Data.Either
+#endif
+import Data.Maybe
#ifdef __GLASGOW_HASKELL__
import GHC.Base
-import Data.Maybe
-import GHC.IOBase
+import GHC.IO
+import GHC.IO.Exception
+import GHC.IO.Handle.Types
import Text.Show
#endif
+#ifdef __HUGS__
+import Hugs.Prelude(Handle, IOException(..), IOErrorType(..), IO)
+#endif
+
+#ifdef __NHC__
+import IO
+ ( IOError ()
+ , Handle ()
+ , try
+ , ioError
+ , userError
+ , isAlreadyExistsError -- :: IOError -> Bool
+ , isDoesNotExistError
+ , isAlreadyInUseError
+ , isFullError
+ , isEOFError
+ , isIllegalOperation
+ , isPermissionError
+ , isUserError
+ , ioeGetErrorString -- :: IOError -> String
+ , ioeGetHandle -- :: IOError -> Maybe Handle
+ , ioeGetFileName -- :: IOError -> Maybe FilePath
+ )
+import qualified NHC.Internal as NHC (IOError(..))
+import qualified NHC.DErrNo as NHC (ErrNo(..))
+import Data.Maybe (fromJust)
+import Control.Monad (MonadPlus(mplus))
+#endif
+
+-- | The construct 'try' @comp@ exposes IO errors which occur within a
+-- computation, and which are not fully handled.
+--
+-- Non-I\/O exceptions are not caught by this variant; to catch all
+-- exceptions, use 'Control.Exception.try' from "Control.Exception".
+
+#ifndef __NHC__
+try :: IO a -> IO (Either IOError a)
+try f = catch (do r <- f
+ return (Right r))
+ (return . Left)
+#endif
+
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
-- -----------------------------------------------------------------------------
-- Constructing an IOError
+-- | Construct an 'IOError' of the given type where the second argument
+-- describes the error location and the third and fourth argument
+-- contain the file handle and file path of the file involved in the
+-- error if applicable.
mkIOError :: IOErrorType -> String -> Maybe Handle -> Maybe FilePath -> IOError
mkIOError t location maybe_hdl maybe_filename =
- IOException IOError{ ioe_type = t,
- ioe_location = location,
- ioe_descr = "",
- ioe_handle = maybe_hdl,
- ioe_filename = maybe_filename
- }
-
+ IOError{ ioe_type = t,
+ ioe_location = location,
+ ioe_description = "",
+#if defined(__GLASGOW_HASKELL__)
+ ioe_errno = Nothing,
+#endif
+ ioe_handle = maybe_hdl,
+ ioe_filename = maybe_filename
+ }
+#endif /* __GLASGOW_HASKELL__ || __HUGS__ */
+#ifdef __NHC__
+mkIOError EOF location maybe_hdl maybe_filename =
+ NHC.EOFError location (fromJust maybe_hdl)
+mkIOError UserError location maybe_hdl maybe_filename =
+ NHC.UserError location ""
+mkIOError t location maybe_hdl maybe_filename =
+ NHC.IOError location maybe_filename maybe_hdl (ioeTypeToErrNo t)
+ where
+ ioeTypeToErrNo AlreadyExists = NHC.EEXIST
+ ioeTypeToErrNo NoSuchThing = NHC.ENOENT
+ ioeTypeToErrNo ResourceBusy = NHC.EBUSY
+ ioeTypeToErrNo ResourceExhausted = NHC.ENOSPC
+ ioeTypeToErrNo IllegalOperation = NHC.EPERM
+ ioeTypeToErrNo PermissionDenied = NHC.EACCES
+#endif /* __NHC__ */
+
+#ifndef __NHC__
-- -----------------------------------------------------------------------------
-- IOErrorType
-isAlreadyExistsError, isDoesNotExistError, isAlreadyInUseError,
- isFullError, isEOFError, isIllegalOperation, isPermissionError,
- isUserError :: IOError -> Bool
-
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments already exists.
+isAlreadyExistsError :: IOError -> Bool
isAlreadyExistsError = isAlreadyExistsErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments does not exist.
+isDoesNotExistError :: IOError -> Bool
isDoesNotExistError = isDoesNotExistErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- one of its arguments is a single-use resource, which is already
+-- being used (for example, opening the same file twice for writing
+-- might give this error).
+isAlreadyInUseError :: IOError -> Bool
isAlreadyInUseError = isAlreadyInUseErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the device is full.
+isFullError :: IOError -> Bool
isFullError = isFullErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the end of file has been reached.
+isEOFError :: IOError -> Bool
isEOFError = isEOFErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the operation was not possible.
+-- Any computation which returns an 'IO' result may fail with
+-- 'isIllegalOperation'. In some cases, an implementation will not be
+-- able to distinguish between the possible error causes. In this case
+-- it should fail with 'isIllegalOperation'.
+isIllegalOperation :: IOError -> Bool
isIllegalOperation = isIllegalOperationErrorType . ioeGetErrorType
+
+-- | An error indicating that an 'IO' operation failed because
+-- the user does not have sufficient operating system privilege
+-- to perform that operation.
+isPermissionError :: IOError -> Bool
isPermissionError = isPermissionErrorType . ioeGetErrorType
+
+-- | A programmer-defined error value constructed using 'userError'.
+isUserError :: IOError -> Bool
isUserError = isUserErrorType . ioeGetErrorType
+#endif /* __NHC__ */
-- -----------------------------------------------------------------------------
-- IOErrorTypes
-#ifdef __GLASGOW_HASKELL__
-alreadyExistsErrorType, doesNotExistErrorType, alreadyInUseErrorType,
- fullErrorType, eofErrorType, illegalOperationErrorType,
- permissionErrorType, userErrorType :: IOErrorType
+#ifdef __NHC__
+data IOErrorType = AlreadyExists | NoSuchThing | ResourceBusy
+ | ResourceExhausted | EOF | IllegalOperation
+ | PermissionDenied | UserError
+#endif
+-- | I\/O error where the operation failed because one of its arguments
+-- already exists.
+alreadyExistsErrorType :: IOErrorType
alreadyExistsErrorType = AlreadyExists
+
+-- | I\/O error where the operation failed because one of its arguments
+-- does not exist.
+doesNotExistErrorType :: IOErrorType
doesNotExistErrorType = NoSuchThing
+
+-- | I\/O error where the operation failed because one of its arguments
+-- is a single-use resource, which is already being used.
+alreadyInUseErrorType :: IOErrorType
alreadyInUseErrorType = ResourceBusy
+
+-- | I\/O error where the operation failed because the device is full.
+fullErrorType :: IOErrorType
fullErrorType = ResourceExhausted
+
+-- | I\/O error where the operation failed because the end of file has
+-- been reached.
+eofErrorType :: IOErrorType
eofErrorType = EOF
+
+-- | I\/O error where the operation is not possible.
+illegalOperationErrorType :: IOErrorType
illegalOperationErrorType = IllegalOperation
+
+-- | I\/O error where the operation failed because the user does not
+-- have sufficient operating system privilege to perform that operation.
+permissionErrorType :: IOErrorType
permissionErrorType = PermissionDenied
-userErrorType = UserError
-#endif
+
+-- | I\/O error that is programmer-defined.
+userErrorType :: IOErrorType
+userErrorType = UserError
-- -----------------------------------------------------------------------------
-- IOErrorType predicates
-isAlreadyExistsErrorType, isDoesNotExistErrorType, isAlreadyInUseErrorType,
- isFullErrorType, isEOFErrorType, isIllegalOperationErrorType,
- isPermissionErrorType, isUserErrorType :: IOErrorType -> Bool
-
-#ifdef __GLASGOW_HASKELL__
+-- | I\/O error where the operation failed because one of its arguments
+-- already exists.
+isAlreadyExistsErrorType :: IOErrorType -> Bool
isAlreadyExistsErrorType AlreadyExists = True
isAlreadyExistsErrorType _ = False
+-- | I\/O error where the operation failed because one of its arguments
+-- does not exist.
+isDoesNotExistErrorType :: IOErrorType -> Bool
isDoesNotExistErrorType NoSuchThing = True
isDoesNotExistErrorType _ = False
+-- | I\/O error where the operation failed because one of its arguments
+-- is a single-use resource, which is already being used.
+isAlreadyInUseErrorType :: IOErrorType -> Bool
isAlreadyInUseErrorType ResourceBusy = True
isAlreadyInUseErrorType _ = False
+-- | I\/O error where the operation failed because the device is full.
+isFullErrorType :: IOErrorType -> Bool
isFullErrorType ResourceExhausted = True
isFullErrorType _ = False
+-- | I\/O error where the operation failed because the end of file has
+-- been reached.
+isEOFErrorType :: IOErrorType -> Bool
isEOFErrorType EOF = True
isEOFErrorType _ = False
+-- | I\/O error where the operation is not possible.
+isIllegalOperationErrorType :: IOErrorType -> Bool
isIllegalOperationErrorType IllegalOperation = True
isIllegalOperationErrorType _ = False
+-- | I\/O error where the operation failed because the user does not
+-- have sufficient operating system privilege to perform that operation.
+isPermissionErrorType :: IOErrorType -> Bool
isPermissionErrorType PermissionDenied = True
isPermissionErrorType _ = False
+-- | I\/O error that is programmer-defined.
+isUserErrorType :: IOErrorType -> Bool
isUserErrorType UserError = True
isUserErrorType _ = False
-#endif
-- -----------------------------------------------------------------------------
-- Miscellaneous
-#ifdef __GLASGOW_HASKELL__
-ioeGetErrorType :: IOError -> IOErrorType
-ioeGetHandle :: IOError -> Maybe Handle
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+ioeGetErrorType :: IOError -> IOErrorType
ioeGetErrorString :: IOError -> String
+ioeGetLocation :: IOError -> String
+ioeGetHandle :: IOError -> Maybe Handle
ioeGetFileName :: IOError -> Maybe FilePath
-ioeGetErrorType (IOException ioe) = ioe_type ioe
-ioeGetErrorType _ = error "System.IO.Error.ioeGetHandle: not an IO error"
+ioeGetErrorType ioe = ioe_type ioe
-ioeGetHandle (IOException ioe) = ioe_handle ioe
-ioeGetHandle _ = error "System.IO.Error.ioeGetHandle: not an IO error"
-
-ioeGetErrorString (IOException ioe)
- | isUserErrorType (ioe_type ioe) = show (ioe_descr ioe)
+ioeGetErrorString ioe
+ | isUserErrorType (ioe_type ioe) = ioe_description ioe
| otherwise = show (ioe_type ioe)
-ioeGetErrorString _ = error "System.IO.Error.ioeGetErrorString: not an IO error"
-ioeGetFileName (IOException ioe) = ioe_filename ioe
-ioeGetFileName _ = error "System.IO.Error.ioeGetFileName: not an IO error"
+ioeGetLocation ioe = ioe_location ioe
+
+ioeGetHandle ioe = ioe_handle ioe
+
+ioeGetFileName ioe = ioe_filename ioe
+
+ioeSetErrorType :: IOError -> IOErrorType -> IOError
+ioeSetErrorString :: IOError -> String -> IOError
+ioeSetLocation :: IOError -> String -> IOError
+ioeSetHandle :: IOError -> Handle -> IOError
+ioeSetFileName :: IOError -> FilePath -> IOError
+
+ioeSetErrorType ioe errtype = ioe{ ioe_type = errtype }
+ioeSetErrorString ioe str = ioe{ ioe_description = str }
+ioeSetLocation ioe str = ioe{ ioe_location = str }
+ioeSetHandle ioe hdl = ioe{ ioe_handle = Just hdl }
+ioeSetFileName ioe filename = ioe{ ioe_filename = Just filename }
+
+#elif defined(__NHC__)
+ioeGetErrorType :: IOError -> IOErrorType
+ioeGetLocation :: IOError -> String
+
+ioeGetErrorType e | isAlreadyExistsError e = AlreadyExists
+ | isDoesNotExistError e = NoSuchThing
+ | isAlreadyInUseError e = ResourceBusy
+ | isFullError e = ResourceExhausted
+ | isEOFError e = EOF
+ | isIllegalOperation e = IllegalOperation
+ | isPermissionError e = PermissionDenied
+ | isUserError e = UserError
+
+ioeGetLocation (NHC.IOError _ _ _ _) = "unknown location"
+ioeGetLocation (NHC.EOFError _ _ ) = "unknown location"
+ioeGetLocation (NHC.PatternError loc) = loc
+ioeGetLocation (NHC.UserError loc _) = loc
+
+ioeSetErrorType :: IOError -> IOErrorType -> IOError
+ioeSetErrorString :: IOError -> String -> IOError
+ioeSetLocation :: IOError -> String -> IOError
+ioeSetHandle :: IOError -> Handle -> IOError
+ioeSetFileName :: IOError -> FilePath -> IOError
+
+ioeSetErrorType e _ = e
+ioeSetErrorString (NHC.IOError _ f h e) s = NHC.IOError s f h e
+ioeSetErrorString (NHC.EOFError _ f) s = NHC.EOFError s f
+ioeSetErrorString e@(NHC.PatternError _) _ = e
+ioeSetErrorString (NHC.UserError l _) s = NHC.UserError l s
+ioeSetLocation e@(NHC.IOError _ _ _ _) _ = e
+ioeSetLocation e@(NHC.EOFError _ _) _ = e
+ioeSetLocation (NHC.PatternError _) l = NHC.PatternError l
+ioeSetLocation (NHC.UserError _ m) l = NHC.UserError l m
+ioeSetHandle (NHC.IOError o f _ e) h = NHC.IOError o f (Just h) e
+ioeSetHandle (NHC.EOFError o _) h = NHC.EOFError o h
+ioeSetHandle e@(NHC.PatternError _) _ = e
+ioeSetHandle e@(NHC.UserError _ _) _ = e
+ioeSetFileName (NHC.IOError o _ h e) f = NHC.IOError o (Just f) h e
+ioeSetFileName e _ = e
#endif
+-- | Catch any 'IOError' that occurs in the computation and throw a
+-- modified version.
+modifyIOError :: (IOError -> IOError) -> IO a -> IO a
+modifyIOError f io = catch io (\e -> ioError (f e))
+
-- -----------------------------------------------------------------------------
-- annotating an IOError
-#ifdef __GLASGOW_HASKELL__
+-- | Adds a location description and maybe a file path and file handle
+-- to an 'IOError'. If any of the file handle or file path is not given
+-- the corresponding value in the 'IOError' remains unaltered.
annotateIOError :: IOError
-> String
- -> Maybe FilePath
-> Maybe Handle
+ -> Maybe FilePath
-> IOError
-annotateIOError (IOException (IOError hdl errTy _ str path)) loc opath ohdl =
- IOException (IOError (hdl `mplus` ohdl) errTy loc str (path `mplus` opath))
+
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+annotateIOError ioe loc hdl path =
+ ioe{ ioe_handle = hdl `mplus` ioe_handle ioe,
+ ioe_location = loc, ioe_filename = path `mplus` ioe_filename ioe }
where
+ mplus :: Maybe a -> Maybe a -> Maybe a
Nothing `mplus` ys = ys
xs `mplus` _ = xs
-annotateIOError exc _ _ _ =
- exc
+#endif /* __GLASGOW_HASKELL__ || __HUGS__ */
+
+#if defined(__NHC__)
+annotateIOError (NHC.IOError msg file hdl code) msg' hdl' file' =
+ NHC.IOError (msg++'\n':msg') (file`mplus`file') (hdl`mplus`hdl') code
+annotateIOError (NHC.EOFError msg hdl) msg' _ _ =
+ NHC.EOFError (msg++'\n':msg') hdl
+annotateIOError (NHC.UserError loc msg) msg' _ _ =
+ NHC.UserError loc (msg++'\n':msg')
+annotateIOError (NHC.PatternError loc) msg' _ _ =
+ NHC.PatternError (loc++'\n':msg')
#endif
+
+#ifndef __HUGS__
+-- | The 'catch' function establishes a handler that receives any 'IOError'
+-- raised in the action protected by 'catch'. An 'IOError' is caught by
+-- the most recent handler established by 'catch'. These handlers are
+-- not selective: all 'IOError's are caught. Exception propagation
+-- must be explicitly provided in a handler by re-raising any unwanted
+-- exceptions. For example, in
+--
+-- > f = catch g (\e -> if IO.isEOFError e then return [] else ioError e)
+--
+-- the function @f@ returns @[]@ when an end-of-file exception
+-- (cf. 'System.IO.Error.isEOFError') occurs in @g@; otherwise, the
+-- exception is propagated to the next outer handler.
+--
+-- When an exception propagates outside the main program, the Haskell
+-- system prints the associated 'IOError' value and exits the program.
+--
+-- Non-I\/O exceptions are not caught by this variant; to catch all
+-- exceptions, use 'Control.Exception.catch' from "Control.Exception".
+catch :: IO a -> (IOError -> IO a) -> IO a
+catch = New.catch
+#endif /* !__HUGS__ */
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