Wolfgang Jeltsch pushed to branch wip/jeltsch/obtaining-os-handles at Glasgow Haskell Compiler / GHC Commits: fd01c7b8 by Wolfgang Jeltsch at 2025-09-09T17:11:46+03:00 Fix the texts regarding handle type errors Note, in particular, that the operations for obtaining operating-system handles also fail with socket-based handles; so failure is not just about the I/O manager in use. - - - - - 1 changed file: - libraries/base/src/GHC/IO/Handle.hs Changes: ===================================== libraries/base/src/GHC/IO/Handle.hs ===================================== @@ -198,38 +198,45 @@ handleStateVarWritingBiased (DuplexHandle _ _ writingVar) = writingVar {-| Yields the result of another operation if that operation succeeded, and otherwise throws an exception that signals that the other operation failed - because a certain I/O subsystem is not in use. + because some Haskell handle does not use an operating-system handle of a + required type. -} -requiringSubsystem :: String - -- ^ The name of the required subsystem - -> Maybe a - -- ^ The result of the other operation if it succeeded - -> IO a -requiringSubsystem subsystemName - = maybe (ioException subsystemRequired) return +requiringOSHandleOfType :: String + -- ^ The name of the operating-system handle type + -> Maybe a + {-^ + The result of the other operation if it succeeded + -} + -> IO a +requiringOSHandleOfType osHandleTypeName + = maybe (ioException osHandleOfTypeRequired) return where - subsystemRequired :: IOException - subsystemRequired = IOError Nothing - IllegalOperation - "" - (subsystemName ++ " I/O subsystem required") - Nothing - Nothing + osHandleOfTypeRequired :: IOException + osHandleOfTypeRequired + = IOError Nothing + IllegalOperation + "" + ("handle does not use " ++ osHandleTypeName ++ "s") + Nothing + Nothing {-| - Obtains the POSIX file descriptor of a device if the POSIX I/O subsystem is - in use, and throws an exception otherwise. + Obtains the POSIX file descriptor of a device if the device contains one, + and throws an exception otherwise. -} getFileDescriptor :: Typeable d => d -> IO CInt -getFileDescriptor = requiringSubsystem "POSIX" . fmap fdFD . cast +getFileDescriptor = requiringOSHandleOfType "POSIX file descriptor" . + fmap fdFD . cast {-| - Obtains the Windows handle of a device if the Windows I/O subsystem is in - use, and throws an exception otherwise. + Obtains the Windows handle of a device if the device contains one, and + throws an exception otherwise. -} getWindowsHandle :: Typeable d => d -> IO (Ptr ()) -getWindowsHandle = requiringSubsystem "native" . toMaybeWindowsHandle where +getWindowsHandle = requiringOSHandleOfType "Windows handle" . + toMaybeWindowsHandle + where toMaybeWindowsHandle :: Typeable d => d -> Maybe (Ptr ()) #if defined(mingw32_HOST_OS) @@ -257,7 +264,7 @@ getWindowsHandle = requiringSubsystem "native" . toMaybeWindowsHandle where further operations on the handle are blocked to a degree that interference with this action is prevented. - If the I/O subsystem in use is not the POSIX one, an exception is thrown. + If the handle does not use POSIX file descriptors, an exception is thrown. See [below](#with-ref-caveats) for caveats regarding this operation. -} @@ -275,7 +282,7 @@ withFileDescriptorReadingBiased = withOSHandle "withFileDescriptorReadingBiased" further operations on the handle are blocked to a degree that interference with this action is prevented. - If the I/O subsystem in use is not the POSIX one, an exception is thrown. + If the handle does not use POSIX file descriptors, an exception is thrown. See [below](#with-ref-caveats) for caveats regarding this operation. -} @@ -293,7 +300,7 @@ withFileDescriptorWritingBiased = withOSHandle "withFileDescriptorWritingBiased" operations on the Haskell handle are blocked to a degree that interference with this action is prevented. - If the I/O subsystem in use is not the Windows one, an exception is thrown. + If the Haskell handle does not use Windows handles, an exception is thrown. See [below](#with-ref-caveats) for caveats regarding this operation. -} @@ -311,7 +318,7 @@ withWindowsHandleReadingBiased = withOSHandle "withWindowsHandleReadingBiased" operations on the Haskell handle are blocked to a degree that interference with this action is prevented. - If the I/O subsystem in use is not the Windows one, an exception is thrown. + If the Haskell handle does not use Windows handles, an exception is thrown. See [below](#with-ref-caveats) for caveats regarding this operation. -} View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fd01c7b8ce5eca29346fcb90257c757f... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fd01c7b8ce5eca29346fcb90257c757f... You're receiving this email because of your account on gitlab.haskell.org.