Make SubStringStub more robust wrt unsafe arguments.

test/cctest/test-strings.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 
 // Check that we can traverse very deep stacks of ConsStrings using
 // StringInputBuffer.  Check that Get(int) works on very deep stacks
 // of ConsStrings.  These operations may not be very fast, but they
 // should be possible without getting errors due to too deep recursion.
 
 #include <stdlib.h>
 
 #include "v8.h"
@@ skipping 602 matching lines @@
   LocalContext context;
   v8::V8::IgnoreOutOfMemoryException();
   v8::Local<v8::Script> script =
       v8::Script::Compile(v8::String::New(join_causing_out_of_memory));
   v8::Local<v8::Value> result = script->Run();
 
   // Check for out of memory state.
   CHECK(result.IsEmpty());
   CHECK(context->HasOutOfMemoryException());
 }
+
+
+TEST(RobustSubStringStub) {
+  // This tests whether the SubStringStub can handle unsafe arguments.
+  // If not recognized, those unsafe arguments lead to out-of-bounds reads.
+  FLAG_allow_natives_syntax = true;
+  InitializeVM();
+  HandleScope scope;
+  v8::Local<v8::Value> result;
+  Handle<String> string;
+  CompileRun("%_SubString('abcdef', 0, 10000)");
+  CompileRun("%_SubString('abcdef', 5, 2)");

[Erik Corry, 2012/04/17 09:06:58]

I'd like more tests here.  Negative numbers, borderline numbers, heap numbers,
input strings large enough to trigger the creation of SlicedStrings, slices of
slices where the args are out of bounds for the slice, but not for the
underlying string.

+}