3 files changed, 49 insertions, 14 deletions
diff --git a/src/BTLS/BoringSSLPatterns.hs b/src/BTLS/BoringSSLPatterns.hs
index e77abcb..44f4b0c 100644
--- a/src/BTLS/BoringSSLPatterns.hs
+++ b/src/BTLS/BoringSSLPatterns.hs
@@ -18,13 +18,12 @@ module BTLS.BoringSSLPatterns
   ) where
 
 import Data.ByteString (ByteString)
-import qualified Data.ByteString as ByteString
-import qualified Data.ByteString.Unsafe as ByteString
 import qualified Data.ByteString.Lazy as ByteString.Lazy
 import Foreign (ForeignPtr, Storable(peek), Ptr, alloca, allocaArray, withForeignPtr)
 import Foreign.C.Types
 
 import BTLS.BoringSSL.Digest (evpMaxMDSize)
+import BTLS.Buffer (packCUStringLen, unsafeUseAsCUStringLen)
 
 type LazyByteString = ByteString.Lazy.ByteString
 
@@ -41,8 +40,8 @@ type LazyByteString = ByteString.Lazy.ByteString
 initUpdateFinalize ::
      IO (ForeignPtr ctx)
   -> (Ptr ctx -> IO ())
-  -> (Ptr ctx -> Ptr CChar -> CULong -> IO ())
-  -> (Ptr ctx -> Ptr CChar -> Ptr CUInt -> IO ())
+  -> (Ptr ctx -> Ptr CUChar -> CULong -> IO ())
+  -> (Ptr ctx -> Ptr CUChar -> Ptr CUInt -> IO ())
   -> LazyByteString
   -> IO ByteString
 initUpdateFinalize mallocCtx initialize update finalize bytes = do
@@ -54,9 +53,8 @@ initUpdateFinalize mallocCtx initialize update finalize bytes = do
   where
     updateBytes ctx chunk =
       -- The updater won't mutate its arguments, so the sharing inherent in
-      -- 'ByteString.unsafeUseAsCStringLen' is fine.
-      ByteString.unsafeUseAsCStringLen chunk $ \(buf, len) ->
-        update ctx buf (fromIntegral len)
+      -- 'unsafeUseAsCUStringLen' is fine.
+      unsafeUseAsCUStringLen chunk $ \(buf, len) -> update ctx buf len
 
 -- | Allocates a buffer, runs a function 'f' to partially fill it, and packs the
 -- filled data into a 'ByteString'. 'f' must write the size of the filled data,
@@ -67,11 +65,11 @@ initUpdateFinalize mallocCtx initialize update finalize bytes = do
 onBufferOfMaxSize ::
      (Integral size, Storable size)
   => Int
-  -> (Ptr CChar -> Ptr size -> IO ())
+  -> (Ptr CUChar -> Ptr size -> IO ())
   -> IO ByteString
 onBufferOfMaxSize maxSize f =
   allocaArray maxSize $ \pOut ->
     alloca $ \pOutLen -> do
       f pOut pOutLen
-      outLen <- fromIntegral <$> peek pOutLen
-      ByteString.packCStringLen (pOut, outLen)
+      outLen <- peek pOutLen
+      packCUStringLen (pOut, outLen)
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
diff --git a/src/BTLS/Cast.hs b/src/BTLS/Cast.hs
index a467c90..6f29469 100644
--- a/src/BTLS/Cast.hs
+++ b/src/BTLS/Cast.hs
@@ -15,11 +15,7 @@
 module BTLS.Cast where
 
 import Foreign (Ptr)
-import Foreign.C.Types
 import Unsafe.Coerce (unsafeCoerce)
 
-asCUCharBuf :: Ptr CChar -> Ptr CUChar
-asCUCharBuf = unsafeCoerce
-
 asVoidPtr :: Ptr a -> Ptr ()
 asVoidPtr = unsafeCoerce