From 87758b27893534d6b7b5c3289dfd83578c7c4ae3 Mon Sep 17 00:00:00 2001
From: Ilya Rezvov <ilya.rezvov@revjet.com>
Date: Sun, 8 Apr 2018 10:53:14 -0700
Subject: [PATCH] fix memory growing for empty data segments

---
 src/Language/Wasm/Interpreter.hs | 3 ++-
 tests/Test.hs                    | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/Language/Wasm/Interpreter.hs b/src/Language/Wasm/Interpreter.hs
index 6df713e..0c56960 100644
--- a/src/Language/Wasm/Interpreter.hs
+++ b/src/Language/Wasm/Interpreter.hs
@@ -316,6 +316,7 @@ initialize inst Module {elems, datas, start} store = do
             return $ st { tableInstances = tableInstances st Vector.// [(idx, table)] }
 
         fitOrGrowMemory :: Address -> Store -> Int -> IO MemoryInstance
+        fitOrGrowMemory idx st 0 = return $ memInstances st ! idx
         fitOrGrowMemory idx st last = do
             let m@(MemoryInstance mem maxLen) = memInstances st ! idx
             let len = IOVector.length mem
@@ -329,7 +330,7 @@ initialize inst Module {elems, datas, start} store = do
                 Nothing -> increased
                 Just max ->
                     let maxInBytes = max * pageSize in
-                    if maxInBytes <= last
+                    if maxInBytes < last
                     then error $ "Max memory length reached. Max " ++ show max ++ "(" ++ show maxInBytes ++ "b), but requested " ++ show last
                     else increased
 
diff --git a/tests/Test.hs b/tests/Test.hs
index 6d63405..9050d50 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 = ["func.wast"]
+  -- let files = ["memory.wast"]
   scriptTestCases <- (`mapM` files) $ \file -> do
     content <- LBS.readFile $ "tests/samples/" ++ file
     let Right script = Parser.parseScript <$> Lexer.scanner content