1 files changed, 41 insertions, 0 deletions
diff --git a/src/BTLS/Buffer.hs b/src/BTLS/Buffer.hs
new file mode 100644
index 0000000..d7b3f14
--- /dev/null
+++ b/src/BTLS/Buffer.hs
@@ -0,0 +1,41 @@
+-- Copyright 2018 Google LLC
+--
+-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
+-- use this file except in compliance with the License. You may obtain a copy of
+-- the License at
+--
+--     https://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+-- License for the specific language governing permissions and limitations under
+-- the License.
+
+module BTLS.Buffer
+  ( unsafeUseAsCUStringLen
+  , packCUStringLen
+  ) where
+
+import Data.ByteString (ByteString)
+import qualified Data.ByteString as ByteString
+import qualified Data.ByteString.Unsafe as ByteString
+import Foreign (Ptr)
+import Foreign.C.Types
+import Unsafe.Coerce (unsafeCoerce)
+
+unsafeUseAsCUStringLen ::
+     Integral n => ByteString -> ((Ptr CUChar, n) -> IO a) -> IO a
+unsafeUseAsCUStringLen bs f =
+  ByteString.unsafeUseAsCStringLen bs $ \(pStr, len) ->
+    f (asCUCharBuf pStr, fromIntegral len)
+
+packCUStringLen :: Integral n => (Ptr CUChar, n) -> IO ByteString
+packCUStringLen (pStr, len) =
+  ByteString.packCStringLen (asCCharBuf pStr, fromIntegral len)
+
+asCUCharBuf :: Ptr CChar -> Ptr CUChar
+asCUCharBuf = unsafeCoerce
+
+asCCharBuf :: Ptr CUChar -> Ptr CChar
+asCCharBuf = unsafeCoerce