Regression test for existing bug in String::MakeExternal.

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 603 matching lines @@
   char* buf = i::NewArray<char>(buf_size);
   memset(buf, 'a', buf_size);
   buf[buf_size - 1] = '\0';
   Local<String> large_string = String::New(buf);
   i::DeleteArray(buf);
   // Large strings should be immediately accepted.
   CHECK(large_string->CanMakeExternal());
 }
 
 
+TEST(MakingExternalUnalignedAsciiString) {
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+
+  // Create a cons string that will land in old pointer space.
+  Local<String> string = Local<String>::Cast(CompileRun(
+      "function cons(a, b) { return a + b; }"
+      "cons('abcdefghijklm', 'nopqrstuvwxyz');"));
+
+  // Trigger GCs so that the newly allocated string moves to old gen.
+  SimulateFullSpace(HEAP->old_pointer_space());
+  HEAP->CollectGarbage(i::NEW_SPACE);  // in survivor space now
+  HEAP->CollectGarbage(i::NEW_SPACE);  // in old gen now
+
+  // Turn into external string with unaligned resource data.
+  int dispose_count = 0;
+  const char* c_source = "_abcdefghijklmnopqrstuvwxyz";
+  bool success = string->MakeExternal(
+      new TestAsciiResource(i::StrDup(c_source) + 1, &dispose_count));
+  CHECK(success);
+
+  // Trigger GCs and force evacuation.
+  HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
+  HEAP->CollectAllGarbage(i::Heap::kReduceMemoryFootprintMask);
+}
+
+
 THREADED_TEST(UsingExternalString) {
   i::Factory* factory = i::Isolate::Current()->factory();
   {
     v8::HandleScope scope(v8::Isolate::GetCurrent());
     uint16_t* two_byte_string = AsciiToTwoByteString("test string");
     Local<String> string =
         String::NewExternal(new TestResource(two_byte_string));
     i::Handle<i::String> istring = v8::Utils::OpenHandle(*string);
     // Trigger GCs so that the newly allocated string moves to old gen.
     HEAP->CollectGarbage(i::NEW_SPACE);  // in survivor space now
@@ skipping 19263 matching lines @@
   CheckCorrectThrow("%HasProperty(other, 'x')");
   CheckCorrectThrow("%HasElement(other, 1)");
   CheckCorrectThrow("%IsPropertyEnumerable(other, 'x')");
   CheckCorrectThrow("%GetPropertyNames(other)");
   CheckCorrectThrow("%GetLocalPropertyNames(other, true)");
   CheckCorrectThrow("%DefineOrRedefineAccessorProperty("
                         "other, 'x', null, null, 1)");
 }
 
 #endif  // WIN32