Begin refactoring low-level foreign imports into their own hierarchy

It’s clear at this point that this system is going to get large enough
that a two-layer implementation is warranted. `Internal` will contain
low-level bindings to BoringSSL; other modules will export an idiomatic
interface on top of them.

6 files changed, 75 insertions, 27 deletions

diff --git a/btls.cabal b/btls.cabal
index 0359ab7..4f46ec3 100644
--- a/btls.cabal
+++ b/btls.cabal
@@ -56,6 +56,8 @@ library
   other-modules:       Data.Digest.Internal
                      , Foreign.Ptr.Cast
                      , Foreign.Ptr.ConstantTimeEquals
+                     , Internal.Base
+                     , Internal.Digest
                      , Result
   c-sources:           cbits/btls.c
   -- Use special names for the BoringSSL libraries to avoid accidentally pulling
diff --git a/src/Data/Digest.chs b/src/Data/Digest.chs
index 09ab518..0ed24d2 100644
--- a/src/Data/Digest.chs
+++ b/src/Data/Digest.chs
@@ -27,6 +27,7 @@ module Data.Digest
 import Foreign (Ptr)
 
 {#import Data.Digest.Internal#}
+{#import Internal.Base#}
 
 #include <openssl/digest.h>
 
diff --git a/src/Data/Digest/Internal.chs b/src/Data/Digest/Internal.chs
index 86cea65..6478810 100644
--- a/src/Data/Digest/Internal.chs
+++ b/src/Data/Digest/Internal.chs
@@ -12,8 +12,6 @@
 -- License for the specific language governing permissions and limitations under
 -- the License.
 
-{-# OPTIONS_GHC -Wno-missing-methods #-}
-
 module Data.Digest.Internal where
 
 import Data.Bits (Bits((.&.)), shiftR)
@@ -24,13 +22,14 @@ import qualified Data.ByteString.Unsafe as ByteString
 import Data.Char (intToDigit)
 import Data.Word (Word8)
 import Foreign
-       (FinalizerPtr, ForeignPtr, Ptr, Storable(alignment, peek, sizeOf),
-        addForeignPtrFinalizer, alloca, allocaArray, mallocForeignPtr,
-        nullPtr, withForeignPtr)
+       (FinalizerPtr, ForeignPtr, Ptr, Storable(peek), addForeignPtrFinalizer,
+        alloca, allocaArray, mallocForeignPtr, withForeignPtr)
 import Foreign.C.Types
 import Foreign.Marshal.Unsafe (unsafeLocalState)
 import Unsafe.Coerce (unsafeCoerce)
 
+{#import Internal.Base#}
+{#import Internal.Digest#} ()
 import Foreign.Ptr.Cast (asVoidPtr)
 import Result
 
@@ -40,26 +39,6 @@ type LazyByteString = ByteString.Lazy.ByteString
 
 -- First, we build basic bindings to the BoringSSL EVP interface.
 
--- | The BoringSSL @ENGINE@ type.
-data Engine
-{#pointer *ENGINE as 'Ptr Engine' -> Engine nocode#}
-
-noEngine :: Ptr Engine
-noEngine = nullPtr
-
--- | The BoringSSL @EVP_MD@ type, representing a hash algorithm.
-data EvpMd
-{#pointer *EVP_MD as 'Ptr EvpMd' -> EvpMd nocode#}
-
--- | The BoringSSL @EVP_MD_CTX@ type, representing the state of a pending
--- hashing operation.
-data EvpMdCtx
-{#pointer *EVP_MD_CTX as 'Ptr EvpMdCtx' -> EvpMdCtx nocode#}
-
-instance Storable EvpMdCtx where
-  sizeOf _ = {#sizeof EVP_MD_CTX#}
-  alignment _ = {#alignof EVP_MD_CTX#}
-
 -- Imported functions from BoringSSL. See
 -- https://commondatastorage.googleapis.com/chromium-boringssl-docs/digest.h.html
 -- for documentation.
diff --git a/src/Data/Hmac.chs b/src/Data/Hmac.chs
index 907c352..e78c1af 100644
--- a/src/Data/Hmac.chs
+++ b/src/Data/Hmac.chs
@@ -33,10 +33,10 @@ import Foreign.Marshal.Unsafe (unsafeLocalState)
 import Unsafe.Coerce (unsafeCoerce)
 
 {#import Data.Digest.Internal#}
-       (Algorithm(Algorithm), Digest(Digest), Engine, EvpMd, evpMaxMdSize,
-        noEngine)
+       (Algorithm(Algorithm), Digest(Digest), evpMaxMdSize)
 import Foreign.Ptr.Cast (asVoidPtr)
 {#import Foreign.Ptr.ConstantTimeEquals#} (constantTimeEquals)
+{#import Internal.Base#}
 import Result
 
 type LazyByteString = ByteString.Lazy.ByteString
diff --git a/src/Internal/Base.chs b/src/Internal/Base.chs
new file mode 100644
index 0000000..552e76b
--- /dev/null
+++ b/src/Internal/Base.chs
@@ -0,0 +1,38 @@
+-- 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.
+
+{-# OPTIONS_GHC -Wno-missing-methods #-}
+{-# OPTIONS_GHC -Wno-unused-imports #-}
+
+module Internal.Base where
+
+import Foreign (Ptr, nullPtr)
+
+#include <openssl/base.h>
+
+-- | The BoringSSL @ENGINE@ type.
+data Engine
+{#pointer *ENGINE as 'Ptr Engine' -> Engine nocode#}
+
+noEngine :: Ptr Engine
+noEngine = nullPtr
+
+-- | The BoringSSL @EVP_MD_CTX@ type, representing the state of a pending
+-- hashing operation.
+data EvpMdCtx
+{#pointer *EVP_MD_CTX as 'Ptr EvpMdCtx' -> EvpMdCtx nocode#}
+
+-- | The BoringSSL @EVP_MD@ type, representing a hash algorithm.
+data EvpMd
+{#pointer *EVP_MD as 'Ptr EvpMd' -> EvpMd nocode#}
diff --git a/src/Internal/Digest.chs b/src/Internal/Digest.chs
new file mode 100644
index 0000000..46b497e
--- /dev/null
+++ b/src/Internal/Digest.chs
@@ -0,0 +1,28 @@
+-- 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.
+
+{-# OPTIONS_GHC -Wno-missing-methods #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
+
+module Internal.Digest where
+
+import Foreign (Storable(alignment, sizeOf))
+
+{#import Internal.Base#}
+
+#include <openssl/digest.h>
+
+instance Storable EvpMdCtx where
+  sizeOf _ = {#sizeof EVP_MD_CTX#}
+  alignment _ = {#alignof EVP_MD_CTX#}