From 6f7ed089017205be016acdb8a633cca76de1355d Mon Sep 17 00:00:00 2001
From: Simon Hengel <sol@typeful.net>
Date: Sat, 4 Nov 2023 22:55:26 +0700
Subject: [PATCH] Add `byteArrayAsForeignPtr`

---
 Data/Primitive/ByteArray.hs | 9 +++++++++
 changelog.md                | 3 +++
 primitive.cabal             | 2 +-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Data/Primitive/ByteArray.hs b/Data/Primitive/ByteArray.hs
index 03d81a9..25daddb 100644
--- a/Data/Primitive/ByteArray.hs
+++ b/Data/Primitive/ByteArray.hs
@@ -62,6 +62,7 @@ module Data.Primitive.ByteArray (
 #if __GLASGOW_HASKELL__ >= 802
   isByteArrayPinned, isMutableByteArrayPinned,
 #endif
+  byteArrayAsForeignPtr,
   byteArrayContents,
   withByteArrayContents,
   mutableByteArrayContents,
@@ -84,6 +85,7 @@ import Data.Word ( Word8 )
 import qualified GHC.Exts as Exts
 #endif
 import GHC.Exts hiding (setByteArray#)
+import GHC.ForeignPtr (ForeignPtr(..), ForeignPtrContents(..))
 
 #if __GLASGOW_HASKELL__ < 804
 import System.IO.Unsafe (unsafeDupablePerformIO)
@@ -128,6 +130,13 @@ newAlignedPinnedByteArray (I# n#) (I# k#)
   = primitive (\s# -> case newAlignedPinnedByteArray# n# k# s# of
                         (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))
 
+-- | Create a foreign pointer that points to the array's data. This operation
+-- is only safe on /pinned/ byte arrays.  The array's data is not garbage
+-- collected while references to the foreign pointer exist.
+byteArrayAsForeignPtr :: ByteArray -> ForeignPtr Word8
+{-# INLINE byteArrayAsForeignPtr #-}
+byteArrayAsForeignPtr (ByteArray arr#) = ForeignPtr (byteArrayContents# arr#) (PlainPtr (unsafeCoerce# arr#))
+
 -- | Yield a pointer to the array's data. This operation is only safe on
 -- /pinned/ byte arrays. Byte arrays allocated by 'newPinnedByteArray' and
 -- 'newAlignedPinnedByteArray' are guaranteed to be pinned. Byte arrays
diff --git a/changelog.md b/changelog.md
index 3b96aff..bdcd77d 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,6 @@
+## Changes in version 0.9.1.0
+  * Add `byteArrayAsForeignPtr`.
+
 ## Changes in version 0.9.0.0
 
   * Add `withByteArrayContents`, `withMutableByteArrayContents`,
diff --git a/primitive.cabal b/primitive.cabal
index 57ecfe9..22c9e35 100644
--- a/primitive.cabal
+++ b/primitive.cabal
@@ -1,6 +1,6 @@
 Cabal-Version:  2.0
 Name:           primitive
-Version:        0.9.0.0
+Version:        0.9.1.0
 License:        BSD3
 License-File:   LICENSE