Fix issue 289: check external source strings validity in Runtime_DebugGetLoadedScripts

Review URL: http://codereview.chromium.org/56002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1630 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -6509,6 +6509,22 @@ static Object* Runtime_DebugEvaluateGlobal(Arguments args) {
 }
 
 
+// If an object given is an external string, check that the underlying
+// resource is accessible. For other kinds of objects, always return true.
+static bool IsExternalStringValid(Object* str) {
+  if (!str->IsString() || !StringShape(String::cast(str)).IsExternal()) {
+    return true;
+  }
+  if (StringShape(String::cast(str)).IsAsciiRepresentation()) {
+    return ExternalAsciiString::cast(str)->resource() != 0;
+  } else if (StringShape(String::cast(str)).IsTwoByteRepresentation()) {
+    return ExternalTwoByteString::cast(str)->resource() != 0;
+  } else {
+    return true;
+  }
+}
+
+
 // Helper function used by Runtime_DebugGetLoadedScripts below.
 static int DebugGetLoadedScripts(FixedArray* instances, int instances_size) {
   NoHandleAllocation ha;
@@ -6520,7 +6536,7 @@ static int DebugGetLoadedScripts(FixedArray* instances, int instances_size) {
   while (iterator.has_next()) {
     HeapObject* obj = iterator.next();
     ASSERT(obj != NULL);
-    if (obj->IsScript()) {
+    if (obj->IsScript() && IsExternalStringValid(Script::cast(obj)->source())) {
       if (instances != NULL && count < instances_size) {
         instances->set(count, obj);
       }

test/cctest/test-debug.cc

@@ -3980,3 +3980,42 @@ TEST(DebuggerAgentProtocolOverflowHeader) {
   delete client;
   delete server;
 }
+
+
+// Test for issue http://code.google.com/p/v8/issues/detail?id=289.
+// Make sure that DebugGetLoadedScripts doesn't return scripts
+// with disposed external source.
+class EmptyExternalStringResource : public v8::String::ExternalStringResource {
+ public:
+  EmptyExternalStringResource() { empty_[0] = 0; }
+  virtual ~EmptyExternalStringResource() {};
+  virtual size_t length() const { return empty_.length(); }
+  virtual const uint16_t* data() const { return empty_.start(); }
+ private:
+  ::v8::internal::EmbeddedVector<uint16_t,1> empty_;
+};
+
+
+TEST(DebugGetLoadedScripts) {
+  v8::HandleScope scope;
+  DebugLocalContext env;
+  EmptyExternalStringResource source_ext_str;
+  v8::Local<v8::String> source = v8::String::NewExternal(&source_ext_str);
+  v8::Handle<v8::Script> evil_script = v8::Script::Compile(source);
+  Handle<i::ExternalTwoByteString> i_source(
+      i::ExternalTwoByteString::cast(*v8::Utils::OpenHandle(*source)));
+  // This situation can happen if source was an external string disposed
+  // by its owner.
+  i_source->set_resource(0);
+
+  bool allow_natives_syntax = i::FLAG_allow_natives_syntax;
+  i::FLAG_allow_natives_syntax = true;
+  CompileRun(
+      "var scripts = %DebugGetLoadedScripts();"
+      "for (var i = 0; i < scripts.length; ++i) {"
+      "    scripts[i].line_ends;"
+      "}"
+  );
+  // Must not crash while accessing line_ends.
+  i::FLAG_allow_natives_syntax = allow_natives_syntax;
+}