Allow unix 2.8.6

blockio/blockio.cabal

@@ -93,17 +93,21 @@ library
 
   if os(linux)
     hs-source-dirs: src-linux
-    other-modules:  System.FS.BlockIO.Internal
-    build-depends:  unix ^>=2.8.7
+    build-depends:  unix ^>=2.8.6
+    other-modules:
+      System.FS.BlockIO.Internal
+      System.FS.BlockIO.Internal.Fcntl
 
     if !flag(serialblockio)
       other-modules: System.FS.BlockIO.Async
       build-depends: blockio-uring ^>=0.1
 
   elif os(osx)
     hs-source-dirs: src-macos
-    build-depends:  unix ^>=2.8.7
-    other-modules:  System.FS.BlockIO.Internal
+    build-depends:  unix ^>=2.8.6
+    other-modules:
+      System.FS.BlockIO.Internal
+      System.FS.BlockIO.Internal.Fcntl
 
   elif os(windows)
     hs-source-dirs: src-windows

blockio/src-linux/System/FS/BlockIO/Internal.hs

@@ -1,16 +1,17 @@
 {-# LANGUAGE CPP #-}
-
 module System.FS.BlockIO.Internal (
     ioHasBlockIO
   ) where
 
 import qualified System.FS.API as FS
 import           System.FS.API (FsPath, Handle (..), HasFS)
 import           System.FS.BlockIO.API (Advice (..), FileOffset, HasBlockIO)
+import qualified System.FS.BlockIO.Internal.Fcntl as Fcntl
 import qualified System.FS.BlockIO.IO.Internal as IOI
 import           System.FS.IO (HandleIO)
 import qualified System.FS.IO.Handle as FS
-import qualified System.Posix.Fcntl as Fcntl
+import qualified System.Posix.Fcntl as Fcntl (Advice (..), fileAdvise,
+                     fileAllocate)
 import qualified System.Posix.Files as Unix
 import qualified System.Posix.Unistd as Unix
 

blockio/src-linux/System/FS/BlockIO/Internal/Fcntl.hsc

@@ -0,0 +1,38 @@
+{-# LANGUAGE CPP #-}
+-- | Compatibility layer for the @unix@ package to provide a @fileSetCaching@ function.
+--
+-- @unix >= 2.8.7@ defines a @fileSetCaching@ function, but @unix < 2.8.7@ does not. This module defines the function for @unix@ versions @< 2.8.7@. The implementation is adapted from https://github.com/haskell/unix/blob/v2.8.8.0/System/Posix/Fcntl.hsc#L116-L182.
+--
+-- NOTE: in the future if we no longer support @unix@ versions @< 2.8.7@, then this module can be removed.
+module System.FS.BlockIO.Internal.Fcntl (fileSetCaching) where
+
+#if MIN_VERSION_unix(2,8,7)
+
+import System.Posix.Fcntl (fileSetCaching)
+
+#else
+
+-- hsc2hs does not define _GNU_SOURCE, so a .hsc file must define it explicitly
+-- or O_DIRECT stays hidden. The unix package doesn’t define it in source, but
+-- its configure script calls AC_USE_SYSTEM_EXTENSIONS, which adds -D_GNU_SOURCE
+-- to the build CFLAGS, and those flags are passed on to hsc2hs through the
+-- generated `config.mk`.
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+
+import           Data.Bits (complement, (.&.), (.|.))
+import           Foreign.C (throwErrnoIfMinus1, throwErrnoIfMinus1_)
+import           System.Posix.Internals
+import           System.Posix.Types (Fd (Fd))
+
+-- | For simplification, we considered that Linux !HAS_F_NOCACHE and HAS_O_DIRECT
+fileSetCaching :: Fd -> Bool -> IO ()
+fileSetCaching (Fd fd) val = do
+    r <- throwErrnoIfMinus1 "fileSetCaching" (c_fcntl_read fd #{const F_GETFL})
+    let r' | val       = fromIntegral r .&. complement opt_val
+           | otherwise = fromIntegral r .|. opt_val
+    throwErrnoIfMinus1_ "fileSetCaching" (c_fcntl_write fd #{const F_SETFL} r')
+  where
+    opt_val = #{const O_DIRECT}
+#endif

blockio/src-macos/System/FS/BlockIO/Internal.hs

@@ -5,11 +5,11 @@ module System.FS.BlockIO.Internal (
 import qualified System.FS.API as FS
 import           System.FS.API (FsPath, Handle (..), HasFS)
 import           System.FS.BlockIO.API (Advice (..), FileOffset, HasBlockIO)
+import qualified System.FS.BlockIO.Internal.Fcntl as Unix
 import qualified System.FS.BlockIO.IO.Internal as IOI
 import qualified System.FS.BlockIO.Serial as Serial
 import           System.FS.IO (HandleIO)
 import qualified System.FS.IO.Handle as FS
-import qualified System.Posix.Fcntl as Unix
 import qualified System.Posix.Files as Unix
 import qualified System.Posix.Unistd as Unix
 

blockio/src-macos/System/FS/BlockIO/Internal/Fcntl.hsc

@@ -0,0 +1,25 @@
+{-# LANGUAGE CPP #-}
+-- | Compatibility layer for the @unix@ package to provide a @fileSetCaching@ function.
+--
+-- @unix >= 2.8.7@ defines a @fileSetCaching@ function, but @unix < 2.8.7@ does not. This module defines the function for @unix@ versions @< 2.8.7@. The implementation is adapted from https://github.com/haskell/unix/blob/v2.8.8.0/System/Posix/Fcntl.hsc#L116-L182.
+--
+-- NOTE: in the future if we no longer support @unix@ versions @< 2.8.7@, then this module can be removed.
+module System.FS.BlockIO.Internal.Fcntl (fileSetCaching) where
+
+#if MIN_VERSION_unix(2,8,7)
+
+import System.Posix.Fcntl (fileSetCaching)
+
+#else
+
+#include <fcntl.h>
+
+import           Foreign.C (throwErrnoIfMinus1_)
+import           System.Posix.Internals
+import           System.Posix.Types (Fd (Fd))
+
+-- | For simplification, we considered that MacOS HAS_F_NOCACHE and !HAS_O_DIRECT
+fileSetCaching :: Fd -> Bool -> IO ()
+fileSetCaching (Fd fd) val = do
+    throwErrnoIfMinus1_ "fileSetCaching" (c_fcntl_write fd #{const F_NOCACHE} (if val then 0 else 1))
+#endif