From 58befc6c45875185a9891c2f886340863350284f Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Fri, 18 Nov 2022 14:39:38 +1300
Subject: [PATCH] Review CharSet bindings for correct memory management.

---
 Graphics/Text/Font/Choose/CharSet.hs | 10 ++++++----
 Graphics/Text/Font/Choose/Value.hs   |  3 ++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/Graphics/Text/Font/Choose/CharSet.hs b/Graphics/Text/Font/Choose/CharSet.hs
index f0a29ab..303ae7d 100644
--- a/Graphics/Text/Font/Choose/CharSet.hs
+++ b/Graphics/Text/Font/Choose/CharSet.hs
@@ -2,7 +2,7 @@ module Graphics.Text.Font.Choose.CharSet where
 
 import Data.Set (Set)
 import qualified Data.Set as Set
-import Graphics.Text.Font.Choose.Result (throwNull)
+import Graphics.Text.Font.Choose.Result (throwNull, throwFalse)
 
 import Data.Word (Word32)
 import Foreign.Ptr
@@ -28,7 +28,8 @@ foreign import ccall "FcCharSetDestroy" fcCharSetDestroy :: CharSet_ -> IO ()
 
 withCharSet :: CharSet -> (CharSet_ -> IO a) -> IO a
 withCharSet chars cb = withNewCharSet $ \chars' -> do
-    forM (Set.elems chars) $ fcCharSetAddChar chars' . fromIntegral . ord
+    forM (Set.elems chars) $ \ch' ->
+        throwFalse <$> (fcCharSetAddChar chars' $ fromIntegral $ ord ch')
     cb chars'
 foreign import ccall "FcCharSetAddChar" fcCharSetAddChar :: CharSet_ -> Word32 -> IO Bool
 
@@ -42,8 +43,9 @@ thawCharSet chars' = allocaBytes fcCHARSET_MAP_SIZE $ \iter' -> alloca $ \next'
             chs <- go
             return (ch:chs)
       }
-    rest <- go
-    return $ Set.fromList $ map (unsafeChr . fromIntegral) (first:rest)
+    if first == maxBound then return Set.empty else do
+        rest <- go
+        return $ Set.fromList $ map (unsafeChr . fromIntegral) (first:rest)
 foreign import ccall "FcCharSetFirstPage" fcCharSetFirstPage ::
     CharSet_ -> Ptr Word32 -> Ptr Word32 -> IO Word32
 foreign import ccall "FcCharSetNextPage" fcCharSetNextPage ::
diff --git a/Graphics/Text/Font/Choose/Value.hs b/Graphics/Text/Font/Choose/Value.hs
index 62f4b4e..9e03e81 100644
--- a/Graphics/Text/Font/Choose/Value.hs
+++ b/Graphics/Text/Font/Choose/Value.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE DeriveGeneric #-}
-module Graphics.Text.Font.Choose.Value where
+module Graphics.Text.Font.Choose.Value (Value(..), Value_, withValue, thawValue,
+    value'Size) where
 
 import Linear.Matrix (M22)
 import Linear.V2 (V2(..))
-- 
2.30.2