Wolfgang Jeltsch pushed to branch wip/jeltsch/obtaining-os-handles at Glasgow Haskell Compiler / GHC Commits: a979a516 by Wolfgang Jeltsch at 2025-09-09T17:18:01+03:00 Add variants of the operations that do not flush buffers - - - - - 1 changed file: - libraries/base/src/GHC/IO/Handle.hs Changes: ===================================== libraries/base/src/GHC/IO/Handle.hs ===================================== @@ -79,7 +79,11 @@ module GHC.IO.Handle withFileDescriptorReadingBiased, withFileDescriptorWritingBiased, withWindowsHandleReadingBiased, - withWindowsHandleWritingBiased + withWindowsHandleWritingBiased, + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw -- ** Caveats -- $with-ref-caveats @@ -90,7 +94,7 @@ import GHC.Internal.IO.Handle import GHC.Internal.Control.Monad (return) import GHC.Internal.Control.Concurrent.MVar (MVar) import GHC.Internal.Control.Exception (mask) -import GHC.Internal.Data.Function ((.), ($)) +import GHC.Internal.Data.Function (const, (.), ($)) import GHC.Internal.Data.Functor (fmap) #if defined(mingw32_HOST_OS) import GHC.Internal.Data.Bool (otherwise) @@ -132,11 +136,11 @@ import GHC.Internal.Foreign.C.Types (CInt) {-| Obtains an operating-system handle that underlies a Haskell handle and - executes a user-provided action on it. The Haskell-managed buffers related - to the operating-system handle are flushed before the user-provided action - is run. While this action is executed, further operations on the Haskell - handle are blocked to a degree that interference with this action is - prevented. + executes a user-provided action on it. Before the user-provided action is + run, user-defined perparation based on the handle state that contains the + operating-system handle is performed. While the user-provided action is + executed, further operations on the Haskell handle are blocked to a degree + that interference with this action is prevented. See [below](#with-ref-caveats) for caveats regarding this operation. -} @@ -149,16 +153,18 @@ withOSHandle :: String -} -> (forall d. Typeable d => d -> IO a) -- ^ Conversion of a device into an operating-system handle + -> (Handle__ -> IO ()) + -- ^ The preparation -> Handle -- ^ The Haskell handle to use -> (a -> IO r) -- ^ The action to execute on the operating-system handle -> IO r -withOSHandle opName handleStateVar getOSHandle handle act +withOSHandle opName handleStateVar getOSHandle prepare handle act = mask $ \ withOriginalMaskingState -> withHandleState $ \ handleState@Handle__ {haDevice = dev} -> do osHandle <- getOSHandle dev - flushBuffer handleState + prepare handleState withOriginalMaskingState $ act osHandle where @@ -272,6 +278,7 @@ withFileDescriptorReadingBiased :: Handle -> (CInt -> IO r) -> IO r withFileDescriptorReadingBiased = withOSHandle "withFileDescriptorReadingBiased" handleStateVarReadingBiased getFileDescriptor + flushBuffer {-| Obtains the POSIX file descriptor that underlies a handle or specifically @@ -290,6 +297,7 @@ withFileDescriptorWritingBiased :: Handle -> (CInt -> IO r) -> IO r withFileDescriptorWritingBiased = withOSHandle "withFileDescriptorWritingBiased" handleStateVarWritingBiased getFileDescriptor + flushBuffer {-| Obtains the Windows handle that underlies a Haskell handle or specifically @@ -308,6 +316,7 @@ withWindowsHandleReadingBiased :: Handle -> (Ptr () -> IO r) -> IO r withWindowsHandleReadingBiased = withOSHandle "withWindowsHandleReadingBiased" handleStateVarReadingBiased getWindowsHandle + flushBuffer {-| Obtains the Windows handle that underlies a Haskell handle or specifically @@ -326,17 +335,62 @@ withWindowsHandleWritingBiased :: Handle -> (Ptr () -> IO r) -> IO r withWindowsHandleWritingBiased = withOSHandle "withWindowsHandleWritingBiased" handleStateVarWritingBiased getWindowsHandle + flushBuffer + +{-| + Like 'withFileDescriptorReadingBiased' except that Haskell-managed buffers + are not flushed. +-} +withFileDescriptorReadingBiasedRaw :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorReadingBiasedRaw + = withOSHandle "withFileDescriptorReadingBiasedRaw" + handleStateVarReadingBiased + getFileDescriptor + (const $ return ()) + +{-| + Like 'withFileDescriptorWritingBiased' except that Haskell-managed buffers + are not flushed. +-} +withFileDescriptorWritingBiasedRaw :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorWritingBiasedRaw + = withOSHandle "withFileDescriptorWritingBiasedRaw" + handleStateVarWritingBiased + getFileDescriptor + (const $ return ()) + +{-| + Like 'withWindowsHandleReadingBiased' except that Haskell-managed buffers + are not flushed. +-} +withWindowsHandleReadingBiasedRaw :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleReadingBiasedRaw + = withOSHandle "withWindowsHandleReadingBiasedRaw" + handleStateVarReadingBiased + getWindowsHandle + (const $ return ()) + +{-| + Like 'withWindowsHandleWritingBiased' except that Haskell-managed buffers + are not flushed. +-} +withWindowsHandleWritingBiasedRaw :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleWritingBiasedRaw + = withOSHandle "withWindowsHandleWritingBiasedRaw" + handleStateVarWritingBiased + getWindowsHandle + (const $ return ()) -- ** Caveats {-$with-ref-caveats - #with-ref-caveats#There are the following caveats regarding each of the - above operations: + #with-ref-caveats#There are the following caveats regarding the above + operations: - * The flushing of buffers can fail if the given handle is readable but not + * Flushing of buffers can fail if the given handle is readable but not seekable. - * If the operation is performed as part of an action executed by + * If one of these operation is performed as part of an action executed by 'unsafePerformIO', 'unsafeInterleaveIO', or one of their “dupable” variants and the user-provided action receives an asychnchronous exception and does not catch it, then the following happens: View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a979a516a57dc3da9561ebd23a59128d... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a979a516a57dc3da9561ebd23a59128d... 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