1 files changed, 29 insertions, 0 deletions
diff --git a/source/Felix/Output/Atomic.hs b/source/Felix/Output/Atomic.hs
new file mode 100644
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+++ b/source/Felix/Output/Atomic.hs
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+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | Sibling-temporary replacement for generated byte artifacts.
+module Felix.Output.Atomic (writeBytesAtomically) where
+
+import Base
+
+import Data.ByteString (ByteString)
+import Data.ByteString qualified as ByteString
+import System.Directory qualified as Directory
+import System.FilePath.Posix qualified as Posix
+
+writeBytesAtomically :: FilePath -> ByteString -> IO ()
+writeBytesAtomically destination bytes = do
+    let directory = Posix.takeDirectory destination
+        template = Posix.takeFileName destination <> ".tmp"
+    bracketOnError
+        (openBinaryTempFileWithDefaultPermissions directory template)
+        cleanupTemporary
+        \(temporary, handle) -> do
+            ByteString.hPut handle bytes
+            hFlush handle
+            hClose handle
+            Directory.renameFile temporary destination
+
+cleanupTemporary :: (FilePath, Handle) -> IO ()
+cleanupTemporary (temporary, handle) = do
+    void (tryIOError (hClose handle))
+    void (tryIOError (Directory.removeFile temporary))