Fixes memory leak of async directory lister

runtime/bin/directory.cc

Index: runtime/bin/directory.cc
diff --git a/runtime/bin/directory.cc b/runtime/bin/directory.cc
index 982a4be0147d5ffad9e0696042a6f8b741c990e5..bb3173f5b63466d6d9bd5d90906edb41802f56b4 100644
--- a/runtime/bin/directory.cc
+++ b/runtime/bin/directory.cc
@@ -7,6 +7,7 @@
 #include "bin/directory.h"
 
 #include "bin/dartutils.h"
+#include "bin/log.h"
 #include "include/dart_api.h"
 #include "platform/assert.h"
 
@@ -139,6 +140,61 @@ void FUNCTION_NAME(Directory_List)(Dart_NativeArguments args) {
 }
 
 
+static const int kAsyncDirectoryListerFieldIndex = 0;
+
+
+void FUNCTION_NAME(Directory_GetAsyncDirectoryListerPointer)(
+    Dart_NativeArguments args) {
+  AsyncDirectoryListing* listing;
+  Dart_Handle dart_this = ThrowIfError(Dart_GetNativeArgument(args, 0));
+  ASSERT(Dart_IsInstance(dart_this));
+  ThrowIfError(Dart_GetNativeInstanceField(
+      dart_this,
+      kAsyncDirectoryListerFieldIndex,
+      reinterpret_cast<intptr_t*>(&listing)));
+  if (listing != NULL) {
+    intptr_t listing_pointer = reinterpret_cast<intptr_t>(listing);
+    // Increment the listing's reference count. This native should only be
+    // be called when we are about to send the AsyncDirectoryListing* to the
+    // IO service.
+    listing->Retain();
+    Dart_SetReturnValue(args, Dart_NewInteger(listing_pointer));
+  }
+}
+
+
+static void ReleaseListing(void* isolate_callback_data,
+                           Dart_WeakPersistentHandle handle,
+                           void* peer) {
+  AsyncDirectoryListing* listing =
+      reinterpret_cast<AsyncDirectoryListing*>(peer);
+  listing->Release();
+}
+
+
+void FUNCTION_NAME(Directory_SetAsyncDirectoryListerPointer)(
+    Dart_NativeArguments args) {
+  Dart_Handle dart_this = ThrowIfError(Dart_GetNativeArgument(args, 0));
+  intptr_t listing_pointer =
+      DartUtils::GetIntptrValue(Dart_GetNativeArgument(args, 1));
+  AsyncDirectoryListing* listing =
+      reinterpret_cast<AsyncDirectoryListing*>(listing_pointer);
+  Dart_NewWeakPersistentHandle(
+      dart_this,
+      reinterpret_cast<void*>(listing),
+      sizeof(*listing),
+      ReleaseListing);
+  Dart_Handle result = Dart_SetNativeInstanceField(
+      dart_this,
+      kAsyncDirectoryListerFieldIndex,
+      listing_pointer);
+  if (Dart_IsError(result)) {
+    Log::PrintErr("SetAsyncDirectoryListerPointer failed\n");
+    Dart_PropagateError(result);
+  }
+}
+
+
 CObject* Directory::CreateRequest(const CObjectArray& request) {
   if ((request.Length() == 1) && request[0]->IsString()) {
     CObjectString path(request[0]);
@@ -226,7 +282,7 @@ CObject* Directory::ListStartRequest(const CObjectArray& request) {
     if (dir_listing->error()) {
       // Report error now, so we capture the correct OSError.
       CObject* err = CObject::NewOSError();
-      delete dir_listing;
+      dir_listing->Release();
       CObjectArray* error = new CObjectArray(CObject::NewArray(3));
       error->SetAt(0, new CObjectInt32(
           CObject::NewInt32(AsyncDirectoryListing::kListError)));
@@ -247,6 +303,7 @@ CObject* Directory::ListNextRequest(const CObjectArray& request) {
     CObjectIntptr ptr(request[0]);
     AsyncDirectoryListing* dir_listing =
         reinterpret_cast<AsyncDirectoryListing*>(ptr.Value());
+    RefCntReleaseScope<AsyncDirectoryListing> rs(dir_listing);
     if (dir_listing->IsEmpty()) {
       return new CObjectArray(CObject::NewArray(0));
     }
@@ -268,7 +325,15 @@ CObject* Directory::ListStopRequest(const CObjectArray& request) {
     CObjectIntptr ptr(request[0]);
     AsyncDirectoryListing* dir_listing =
         reinterpret_cast<AsyncDirectoryListing*>(ptr.Value());
-    delete dir_listing;
+    RefCntReleaseScope<AsyncDirectoryListing> rs(dir_listing);
+
+    // We have retained a reference to the listing here. Therefore the listing's
+    // destructor can't be running. Since no further requests are dispatched by
+    // the Dart code after an async stop call, this PopAll() can't be racing
+    // with any other call on the listing. We don't do an extra Release(), and
+    // we don't delete the weak persistent handle. The file is closed here, but
+    // the memory for the listing will be cleaned up when the finalizer runs.
+    dir_listing->PopAll();
     return new CObjectBool(CObject::Bool(true));
   }
   return CreateIllegalArgumentError();