core: optionally encrypt SMP files (#3082)

* core: optionally encrypt SMP files

* encrypt to temp file and rename or remove encryption args if it fails

* fix file encryption error handling

src/Simplex/Chat/Util.hs

@@ -1,6 +1,32 @@
-module Simplex.Chat.Util (week) where
+module Simplex.Chat.Util (week, encryptFile, chunkSize) where
 
+import Control.Monad
+import Control.Monad.Except
+import Control.Monad.IO.Class
+import qualified Data.ByteString.Lazy as LB
 import Data.Time (NominalDiffTime)
+import Simplex.Messaging.Crypto.File (CryptoFile (..), CryptoFileArgs (..))
+import qualified Simplex.Messaging.Crypto.File as CF
+import UnliftIO.IO (IOMode (..), withFile)
 
 week :: NominalDiffTime
 week = 7 * 86400
+
+encryptFile :: FilePath -> FilePath -> CryptoFileArgs -> ExceptT String IO ()
+encryptFile fromPath toPath cfArgs = do
+  let toFile = CryptoFile toPath $ Just cfArgs
+  -- uncomment to test encryption error in runTestFileTransferEncrypted
+  -- throwError "test error"
+  withExceptT show $
+    withFile fromPath ReadMode $ \r -> CF.withFile toFile WriteMode $ \w -> do
+      encryptChunks r w
+      liftIO $ CF.hPutTag w
+  where
+    encryptChunks r w = do
+      ch <- liftIO $ LB.hGet r chunkSize
+      unless (LB.null ch) $ liftIO $ CF.hPut w ch
+      unless (LB.length ch < chunkSize) $ encryptChunks r w
+
+chunkSize :: Num a => a
+chunkSize = 65536
+{-# INLINE chunkSize #-}