From 59b9a32b34d3724157aa8883a81213abe7be61d8 Mon Sep 17 00:00:00 2001
From: "yangguo@chromium.org"
 <yangguo@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Tue, 11 Sep 2012 14:16:56 +0000
Subject: [PATCH] Fix edge case of extension with NULL as source string.

BUG=144649

Review URL: https://chromiumcodereview.appspot.com/10914201

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12485 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/api.cc                  |  4 +++-
 src/objects.h               |  2 +-
 test/cctest/test-api.cc     | 12 ++++++++++++
 test/cctest/test-strings.cc |  7 +++++++
 4 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/api.cc b/src/api.cc
index 8b323b2..5c76e32 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -541,7 +541,9 @@ Extension::Extension(const char* name,
       source_(source, source_length_),
       dep_count_(dep_count),
       deps_(deps),
-      auto_enable_(false) { }
+      auto_enable_(false) {
+  CHECK(source != NULL || source_length_ == 0);
+}
 
 
 v8::Handle<Primitive> Undefined() {
diff --git a/src/objects.h b/src/objects.h
index 9b33a43..45a2ac0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7386,7 +7386,7 @@ class String: public HeapObject {
 #ifdef V8_HOST_CAN_READ_UNALIGNED
     ASSERT(kMaxAsciiCharCode == 0x7F);
     const uintptr_t non_ascii_mask = kUintptrAllBitsSet / 0xFF * 0x80;
-    while (chars <= limit - sizeof(uintptr_t)) {
+    while (chars + sizeof(uintptr_t) <= limit) {
       if (*reinterpret_cast<const uintptr_t*>(chars) & non_ascii_mask) {
         return false;
       }
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index f7d8d80..4bd99a6 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -4671,6 +4671,18 @@ THREADED_TEST(SimpleExtensions) {
 }
 
 
+THREADED_TEST(NullExtensions) {
+  v8::HandleScope handle_scope;
+  v8::RegisterExtension(new Extension("nulltest", NULL));
+  const char* extension_names[] = { "nulltest" };
+  v8::ExtensionConfiguration extensions(1, extension_names);
+  v8::Handle<Context> context = Context::New(&extensions);
+  Context::Scope lock(context);
+  v8::Handle<Value> result = Script::Compile(v8_str("1+3"))->Run();
+  CHECK_EQ(result, v8::Integer::New(4));
+}
+
+
 static const char* kEmbeddedExtensionSource =
     "function Ret54321(){return 54321;}~~@@$"
     "$%% THIS IS A SERIES OF NON-NULL-TERMINATED STRINGS.";
diff --git a/test/cctest/test-strings.cc b/test/cctest/test-strings.cc
index 4557100..5a9ccbb 100644
--- a/test/cctest/test-strings.cc
+++ b/test/cctest/test-strings.cc
@@ -11,6 +11,7 @@
 
 #include "api.h"
 #include "factory.h"
+#include "objects.h"
 #include "cctest.h"
 #include "zone-inl.h"
 
@@ -708,3 +709,9 @@ TEST(StringReplaceAtomTwoByteResult) {
   v8::Local<v8::String> expected = v8_str("ascii\x80only\x80string\x80");
   CHECK(expected->Equals(result));
 }
+
+
+TEST(IsAscii) {
+  CHECK(String::IsAscii(static_cast<char*>(NULL), 0));
+  CHECK(String::IsAscii(static_cast<uc16*>(NULL), 0));
+}
-- 
2.7.4