From c644578d8b83dda5e3129579f2e24fb0b5ed99b1 Mon Sep 17 00:00:00 2001
From: Ilya Rezvov <ilya.rezvov@revjet.com>
Date: Tue, 10 Apr 2018 21:25:54 -0700
Subject: [PATCH] fix memory growing behavior

---
 src/Language/Wasm/Interpreter.hs | 6 +++---
 tests/Test.hs                    | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Language/Wasm/Interpreter.hs b/src/Language/Wasm/Interpreter.hs
index 12ade8d..ca65b1d 100644
--- a/src/Language/Wasm/Interpreter.hs
+++ b/src/Language/Wasm/Interpreter.hs
@@ -794,12 +794,12 @@ eval store FunctionInstance { funcType, moduleInstance, code = Function { localT
         step ctx@EvalCtx{ stack = (VI32 n:rest) } GrowMemory = do
             let ref = memInstances store ! (memaddrs moduleInstance ! 0)
             MemoryInstance { memory, maxLen } <- readIORef ref
-            let size = fromIntegral $ IOVector.length memory `div` pageSize
+            let size = fromIntegral $ IOVector.length memory `quot` pageSize
             let growTo = size + fromIntegral n
             result <- (
-                    if fromMaybe True ((growTo <=) <$> maxLen)
+                    if fromMaybe True ((growTo <=) <$> maxLen) && growTo <= 0xFFFF
                     then do
-                        mem' <- IOVector.grow memory $ growTo * pageSize
+                        mem' <- IOVector.grow memory $ fromIntegral n * pageSize
                         writeIORef ref $ MemoryInstance mem' maxLen
                         return size
                     else return $ -1
diff --git a/tests/Test.hs b/tests/Test.hs
index f98a53e..febd4af 100644
--- a/tests/Test.hs
+++ b/tests/Test.hs
@@ -34,7 +34,7 @@ compile file = do
 main :: IO ()
 main = do
   files <- Directory.listDirectory "tests/samples"
-  -- let files = ["memory.wast"]
+  -- let files = ["resizing.wast"]
   scriptTestCases <- (`mapM` files) $ \file -> do
     content <- LBS.readFile $ "tests/samples/" ++ file
     let Right script = Parser.parseScript <$> Lexer.scanner content