-- Stability : provisional
-- Portability : portable
--
--- C-specific Marshalling support: Handling of C \"errno\" error codes
+-- C-specific Marshalling support: Handling of C \"errno\" error codes.
--
-----------------------------------------------------------------------------
module Foreign.C.Error (
- -- Haskell representation for "errno" values
- --
+ -- * Haskell representations of @errno@ values
+
Errno(..), -- instance: Eq
+
+ -- ** Common @errno@ symbols
+ -- | Different operating systems and\/or C libraries often support
+ -- different values of @errno@. This module defines the common values,
+ -- but due to the open definition of 'Errno' users may add definitions
+ -- which are not predefined.
eOK, e2BIG, eACCES, eADDRINUSE, eADDRNOTAVAIL, eADV, eAFNOSUPPORT, eAGAIN,
eALREADY, eBADF, eBADMSG, eBADRPC, eBUSY, eCHILD, eCOMM, eCONNABORTED,
eCONNREFUSED, eCONNRESET, eDEADLK, eDESTADDRREQ, eDIRTY, eDOM, eDQUOT,
eRANGE, eREMCHG, eREMOTE, eROFS, eRPCMISMATCH, eRREMOTE, eSHUTDOWN,
eSOCKTNOSUPPORT, eSPIPE, eSRCH, eSRMNT, eSTALE, eTIME, eTIMEDOUT,
eTOOMANYREFS, eTXTBSY, eUSERS, eWOULDBLOCK, eXDEV,
+
+ -- ** 'Errno' functions
-- :: Errno
isValidErrno, -- :: Errno -> Bool
--
throwErrno, -- :: String -> IO a
- -- guards for IO operations that may fail
- --
+ -- ** Guards for IO operations that may fail
+
throwErrnoIf, -- :: (a -> Bool) -> String -> IO a -> IO a
throwErrnoIf_, -- :: (a -> Bool) -> String -> IO a -> IO ()
throwErrnoIfRetry, -- :: (a -> Bool) -> String -> IO a -> IO a
-- "errno" type
-- ------------
--- Haskell representation for "errno" values
---
+-- | Haskell representation for @errno@ values.
+-- The implementation is deliberately exposed, to allow users to add
+-- their own definitions of 'Errno' values.
+
newtype Errno = Errno CInt
instance Eq Errno where
eXDEV = Errno (CONST_EXDEV)
#endif
--- checks whether the given errno value is supported on the current
--- architecture
+-- | Yield 'True' if the given 'Errno' value is valid on the system.
+-- This implies that the 'Eq' instance of 'Errno' is also system dependent
+-- as it is only defined for valid values of 'Errno'.
--
isValidErrno :: Errno -> Bool
--
-- access to the current thread's "errno" value
-- --------------------------------------------
--- yield the current thread's "errno" value
+-- | Get the current value of @errno@ in the current thread.
--
getErrno :: IO Errno
foreign import ccall unsafe "HsBase.h __hscore_get_errno" get_errno :: IO CInt
#endif
--- set the current thread's "errno" value to 0
+-- | Reset the current thread\'s @errno@ value to 'eOK'.
--
resetErrno :: IO ()
-- throw current "errno" value
-- ---------------------------
--- the common case: throw an IO error based on a textual description
--- of the error location and the current thread's "errno" value
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'.
--
-throwErrno :: String -> IO a
+throwErrno :: String -- ^ textual description of the error location
+ -> IO a
throwErrno loc =
do
errno <- getErrno
-- guards for IO operations that may fail
-- --------------------------------------
--- guard an IO operation and throw an "errno" based exception of the result
--- value of the IO operation meets the given predicate
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'
+-- if the result value of the 'IO' action meets the given predicate.
--
-throwErrnoIf :: (a -> Bool) -> String -> IO a -> IO a
+throwErrnoIf :: (a -> Bool) -- ^ predicate to apply to the result value
+ -- of the 'IO' operation
+ -> String -- ^ textual description of the location
+ -> IO a -- ^ the 'IO' operation to be executed
+ -> IO a
throwErrnoIf pred loc f =
do
res <- f
if pred res then throwErrno loc else return res
--- as `throwErrnoIf', but discards the result
+-- | as 'throwErrnoIf', but discards the result of the 'IO' action after
+-- error handling.
--
-throwErrnoIf_ :: (a -> Bool) -> String -> IO a -> IO ()
+throwErrnoIf_ :: (a -> Bool) -> String -> IO a -> IO ()
throwErrnoIf_ pred loc f = void $ throwErrnoIf pred loc f
--- as `throwErrnoIf', but retries interrupted IO operations (ie, those whose
--- flag `EINTR')
+-- | as 'throwErrnoIf', but retry the 'IO' action when it yields the
+-- error code 'eINTR' - this amounts to the standard retry loop for
+-- interrupted POSIX system calls.
--
throwErrnoIfRetry :: (a -> Bool) -> String -> IO a -> IO a
throwErrnoIfRetry pred loc f =
else throwErrno loc
else return res
--- as `throwErrnoIfRetry', but checks for operations that would block and
--- executes an alternative action in that case.
-
-throwErrnoIfRetryMayBlock :: (a -> Bool) -> String -> IO a -> IO b -> IO a
+-- | as 'throwErrnoIfRetry', but checks for operations that would block and
+-- executes an alternative action before retrying in that case.
+--
+throwErrnoIfRetryMayBlock
+ :: (a -> Bool) -- ^ predicate to apply to the result value
+ -- of the 'IO' operation
+ -> String -- ^ textual description of the location
+ -> IO a -- ^ the 'IO' operation to be executed
+ -> IO b -- ^ action to execute before retrying if
+ -- an immediate retry would block
+ -> IO a
throwErrnoIfRetryMayBlock pred loc f on_block =
do
res <- f
else throwErrno loc
else return res
--- as `throwErrnoIfRetry', but discards the result
+-- | as 'throwErrnoIfRetry', but discards the result.
--
throwErrnoIfRetry_ :: (a -> Bool) -> String -> IO a -> IO ()
throwErrnoIfRetry_ pred loc f = void $ throwErrnoIfRetry pred loc f
--- as `throwErrnoIfRetryMayBlock', but discards the result
+-- | as 'throwErrnoIfRetryMayBlock', but discards the result.
--
throwErrnoIfRetryMayBlock_ :: (a -> Bool) -> String -> IO a -> IO b -> IO ()
throwErrnoIfRetryMayBlock_ pred loc f on_block
= void $ throwErrnoIfRetryMayBlock pred loc f on_block
--- throws "errno" if a result of "-1" is returned
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'
+-- if the 'IO' action returns a result of @-1@.
--
throwErrnoIfMinus1 :: Num a => String -> IO a -> IO a
throwErrnoIfMinus1 = throwErrnoIf (== -1)
--- as `throwErrnoIfMinus1', but discards the result
+-- | as 'throwErrnoIfMinus1', but discards the result.
--
throwErrnoIfMinus1_ :: Num a => String -> IO a -> IO ()
throwErrnoIfMinus1_ = throwErrnoIf_ (== -1)
--- throws "errno" if a result of "-1" is returned, but retries in case of an
--- interrupted operation
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'
+-- if the 'IO' action returns a result of @-1@, but retries in case of
+-- an interrupted operation.
--
throwErrnoIfMinus1Retry :: Num a => String -> IO a -> IO a
throwErrnoIfMinus1Retry = throwErrnoIfRetry (== -1)
--- as `throwErrnoIfMinus1', but discards the result
+-- | as 'throwErrnoIfMinus1', but discards the result.
--
throwErrnoIfMinus1Retry_ :: Num a => String -> IO a -> IO ()
throwErrnoIfMinus1Retry_ = throwErrnoIfRetry_ (== -1)
--- as throwErrnoIfMinus1Retry, but checks for operations that would block
+-- | as 'throwErrnoIfMinus1Retry', but checks for operations that would block.
--
throwErrnoIfMinus1RetryMayBlock :: Num a => String -> IO a -> IO b -> IO a
throwErrnoIfMinus1RetryMayBlock = throwErrnoIfRetryMayBlock (== -1)
--- as `throwErrnoIfMinus1RetryMayBlock', but discards the result
+-- | as 'throwErrnoIfMinus1RetryMayBlock', but discards the result.
--
throwErrnoIfMinus1RetryMayBlock_ :: Num a => String -> IO a -> IO b -> IO ()
throwErrnoIfMinus1RetryMayBlock_ = throwErrnoIfRetryMayBlock_ (== -1)
--- throws "errno" if a result of a NULL pointer is returned
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'
+-- if the 'IO' action returns 'nullPtr'.
--
throwErrnoIfNull :: String -> IO (Ptr a) -> IO (Ptr a)
throwErrnoIfNull = throwErrnoIf (== nullPtr)
--- throws "errno" if a result of a NULL pointer is returned, but retries in
--- case of an interrupted operation
+-- | Throw an 'IOError' corresponding to the current value of 'getErrno'
+-- if the 'IO' action returns 'nullPtr',
+-- but retry in case of an interrupted operation.
--
throwErrnoIfNullRetry :: String -> IO (Ptr a) -> IO (Ptr a)
throwErrnoIfNullRetry = throwErrnoIfRetry (== nullPtr)
--- as throwErrnoIfNullRetry, but checks for operations that would block
+-- | as 'throwErrnoIfNullRetry', but checks for operations that would block.
--
throwErrnoIfNullRetryMayBlock :: String -> IO (Ptr a) -> IO b -> IO (Ptr a)
throwErrnoIfNullRetryMayBlock = throwErrnoIfRetryMayBlock (== nullPtr)
-- conversion of an "errno" value into IO error
-- --------------------------------------------
--- convert a location string, an "errno" value, an optional handle,
--- and an optional filename into a matching IO error
+-- | Construct a Haskell 98 I\/O error based on the given 'Errno' value.
+-- The optional information can be used to improve the accuracy of
+-- error messages.
--
-errnoToIOError :: String -> Errno -> Maybe Handle -> Maybe String -> IOError
+errnoToIOError :: String -- ^ the location where the error occurred
+ -> Errno -- ^ the error number
+ -> Maybe Handle -- ^ optional handle associated with the error
+ -> Maybe String -- ^ optional filename associated with the error
+ -> IOError
errnoToIOError loc errno maybeHdl maybeName = unsafePerformIO $ do
str <- strerror errno >>= peekCString
#if __GLASGOW_HASKELL__
-----------------------------------------------------------------------------
module Foreign.C.Types
+ ( -- * Representations of C types
#ifndef __NHC__
- ( -- Integral types, instances of: Eq, Ord, Num, Read, Show, Enum,
- -- Typeable, Storable, Bounded, Real, Integral, Bits
+ -- $ctypes
+
+ -- ** Integral types
+ -- | These types are are represented as @newtype@s of types in
+ -- "Data.Int" and "Data.Word", and are instances of
+ -- 'Eq', 'Ord', 'Num', 'Read', 'Show', 'Enum', 'Typeable',
+ -- 'Storable', 'Bounded', 'Real', 'Integral' and 'Bits'.
CChar, CSChar, CUChar
, CShort, CUShort, CInt, CUInt
, CLong, CULong
, CPtrdiff, CSize, CWchar, CSigAtomic
, CLLong, CULLong
- -- Numeric types, instances of: Eq, Ord, Num, Read, Show, Enum,
- -- Typeable, Storable
+
+ -- ** Numeric types
+ -- | These types are are represented as @newtype@s of basic
+ -- foreign types, and are instances of
+ -- 'Eq', 'Ord', 'Num', 'Read', 'Show', 'Enum', 'Typeable' and
+ -- 'Storable'.
, CClock, CTime
- -- Floating types, instances of: Eq, Ord, Num, Read, Show, Enum,
- -- Typeable, Storable, Real, Fractional, Floating, RealFrac,
- -- RealFloat
+ -- ** Floating types
+ -- | These types are are represented as @newtype@s of 'Float'
+ -- and 'Double', and are instances of
+ -- 'Eq', 'Ord', 'Num', 'Read', 'Show', 'Enum', 'Typeable',
+ -- 'Storable', 'Real', 'Fractional', 'Floating', 'RealFrac'
+ -- and 'RealFloat'.
, CFloat, CDouble, CLDouble
#else
- ( -- Exported non-abstractly in nhc98 to fix an interface file problem.
+ -- Exported non-abstractly in nhc98 to fix an interface file problem.
CChar(..), CSChar(..), CUChar(..)
, CShort(..), CUShort(..), CInt(..), CUInt(..)
, CLong(..), CULong(..)
, CClock(..), CTime(..)
, CFloat(..), CDouble(..), CLDouble(..)
#endif
+ -- ** Other types
-- Instances of: Eq and Storable
, CFile, CFpos, CJmpBuf
#include "Typeable.h"
#include "CTypes.h"
+-- | Haskell type representing the C @char@ type.
INTEGRAL_TYPE(CChar,tyConCChar,"CChar",HTYPE_CHAR)
+-- | Haskell type representing the C @signed char@ type.
INTEGRAL_TYPE(CSChar,tyConCSChar,"CSChar",HTYPE_SIGNED_CHAR)
+-- | Haskell type representing the C @unsigned char@ type.
INTEGRAL_TYPE(CUChar,tyConCUChar,"CUChar",HTYPE_UNSIGNED_CHAR)
+-- | Haskell type representing the C @short@ type.
INTEGRAL_TYPE(CShort,tyConCShort,"CShort",HTYPE_SHORT)
+-- | Haskell type representing the C @unsigned short@ type.
INTEGRAL_TYPE(CUShort,tyConCUShort,"CUShort",HTYPE_UNSIGNED_SHORT)
+-- | Haskell type representing the C @int@ type.
INTEGRAL_TYPE(CInt,tyConCInt,"CInt",HTYPE_INT)
+-- | Haskell type representing the C @unsigned int@ type.
INTEGRAL_TYPE(CUInt,tyConCUInt,"CUInt",HTYPE_UNSIGNED_INT)
+-- | Haskell type representing the C @long@ type.
INTEGRAL_TYPE(CLong,tyConCLong,"CLong",HTYPE_LONG)
+-- | Haskell type representing the C @unsigned long@ type.
INTEGRAL_TYPE(CULong,tyConCULong,"CULong",HTYPE_UNSIGNED_LONG)
+-- | Haskell type representing the C @long long@ type.
INTEGRAL_TYPE(CLLong,tyConCLLong,"CLLong",HTYPE_LONG_LONG)
+-- | Haskell type representing the C @unsigned long long@ type.
INTEGRAL_TYPE(CULLong,tyConCULLong,"CULLong",HTYPE_UNSIGNED_LONG_LONG)
{-# RULES
"fromIntegral/CULLong->a" fromIntegral = \(CULLong x) -> fromIntegral x
#-}
+-- | Haskell type representing the C @float@ type.
FLOATING_TYPE(CFloat,tyConCFloat,"CFloat",HTYPE_FLOAT)
+-- | Haskell type representing the C @double@ type.
FLOATING_TYPE(CDouble,tyConCDouble,"CDouble",HTYPE_DOUBLE)
-- HACK: Currently no long double in the FFI, so we simply re-use double
+-- | Haskell type representing the C @long double@ type.
FLOATING_TYPE(CLDouble,tyConCLDouble,"CLDouble",HTYPE_DOUBLE)
{-# RULES
"realToFrac/CLDouble->a" realToFrac = \(CLDouble x) -> realToFrac x
#-}
+-- | Haskell type representing the C @ptrdiff_t@ type.
INTEGRAL_TYPE(CPtrdiff,tyConCPtrdiff,"CPtrdiff",HTYPE_PTRDIFF_T)
+-- | Haskell type representing the C @size_t@ type.
INTEGRAL_TYPE(CSize,tyConCSize,"CSize",HTYPE_SIZE_T)
+-- | Haskell type representing the C @wchar_t@ type.
INTEGRAL_TYPE(CWchar,tyConCWchar,"CWchar",HTYPE_WCHAR_T)
+-- | Haskell type representing the C @sig_atomic_t@ type.
INTEGRAL_TYPE(CSigAtomic,tyConCSigAtomic,"CSigAtomic",HTYPE_SIG_ATOMIC_T)
{-# RULES
"fromIntegral/CSigAtomic->a" fromIntegral = \(CSigAtomic x) -> fromIntegral x
#-}
+-- | Haskell type representing the C @clock_t@ type.
ARITHMETIC_TYPE(CClock,tyConCClock,"CClock",HTYPE_CLOCK_T)
+-- | Haskell type representing the C @time_t@ type.
ARITHMETIC_TYPE(CTime,tyConCTime,"CTime",HTYPE_TIME_T)
-- FIXME: Implement and provide instances for Eq and Storable
+-- | Haskell type representing the C @FILE@ type.
data CFile = CFile
+-- | Haskell type representing the C @fpos_t@ type.
data CFpos = CFpos
+-- | Haskell type representing the C @jmp_buf@ type.
data CJmpBuf = CJmpBuf
-- C99 types which are still missing include:
-- intptr_t, uintptr_t, intmax_t, uintmax_t, wint_t, wctrans_t, wctype_t
+{- $ctypes
+
+These types are needed to accurately represent C function prototypes,
+in order to access C library interfaces in Haskell. The Haskell system
+is not required to represent those types exactly as C does, but the
+following guarantees are provided concerning a Haskell type @CT@
+representing a C type @t@:
+
+* If a C function prototype has @t@ as an argument or result type,
+ the use of @CT@ in the corresponding position in a foreign declaration
+ permits the Haskell program to access the full range of values encoded by
+ the C type; and conversely, any Haskell value for @CT@ has a valid
+ representation in C.
+
+* @'sizeOf' ('undefined' :: CT)@ will yield the same value as
+ @sizeof (t)@ in C.
+
+* @'alignment' ('undefined' :: CT)@ matches the alignment constraint
+ enforced by the C implementation for @t@.
+
+* The members 'peek' and 'poke' of the 'Storable' class map all values of
+ @CT@ to the corresponding value of @t@ and vice versa.
+
+* When an instance of 'Bounded' is defined for @CT@, the values of
+ 'minBound' and 'maxBound' coincide with @t_MIN@ and @t_MAX@ in C.
+
+* When an instance of 'Eq' or 'Ord' is defined for @CT@, the predicates
+ defined by the type class implement the same relation as the
+ corresponding predicate in C on @t@.
+
+* When an instance of 'Num', 'Read', 'Integral', 'Fractional', 'Floating',
+ 'RealFrac', or 'RealFloat' is defined for @CT@, the arithmetic
+ operations defined by the type class implement the same function as
+ the corresponding arithmetic operations (if available) in C on @t@.
+
+* When an instance of 'Bits' is defined for @CT@, the bitwise operation
+ defined by the type class implement the same function as the
+ corresponding bitwise operation in C on @t@.
+
+-}
+
#else /* __NHC__ */
import NHC.FFI
-- Stability : provisional
-- Portability : portable
--
--- Marshalling support: Handling of common error conditions
+-- Routines for testing return values and raising a 'userError' exception
+-- in case of values indicating an error state.
--
-----------------------------------------------------------------------------
module Foreign.Marshal.Error (
- -- * Error utilities
-
- -- |Throw an exception on specific return values
- --
throwIf, -- :: (a -> Bool) -> (a -> String) -> IO a -> IO a
throwIf_, -- :: (a -> Bool) -> (a -> String) -> IO a -> IO ()
throwIfNeg, -- :: (Ord a, Num a)
import Foreign.Ptr
#ifdef __GLASGOW_HASKELL__
+#ifdef __HADDOCK__
+import Data.Bool
+import System.IO.Error
+#endif
import GHC.Base
import GHC.Num
import GHC.IOBase
-- exported functions
-- ------------------
--- |Guard an 'IO' operation and throw an exception if the result meets the given
--- predicate
---
--- * the second argument computes an error message from the result of the 'IO'
--- operation
+-- |Execute an 'IO' action, throwing a 'userError' if the predicate yields
+-- 'True' when applied to the result returned by the 'IO' action.
+-- If no exception is raised, return the result of the computation.
--
-throwIf :: (a -> Bool) -> (a -> String) -> IO a -> IO a
+throwIf :: (a -> Bool) -- ^ error condition on the result of the 'IO' action
+ -> (a -> String) -- ^ computes an error message from erroneous results
+ -- of the 'IO' action
+ -> IO a -- ^ the 'IO' action to be executed
+ -> IO a
throwIf pred msgfct act =
do
res <- act
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