From e15dd966d523731101f70ccf768bba12435a0208 Mon Sep 17 00:00:00 2001
From: Lorry Tar Creator <lorry-tar-importer@lorry>
Date: Thu, 15 Oct 2015 09:45:50 +0000
Subject: webkitgtk-2.10.2

---
 .../runtime/StringRecursionChecker.h               | 97 ++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 Source/JavaScriptCore/runtime/StringRecursionChecker.h

(limited to 'Source/JavaScriptCore/runtime/StringRecursionChecker.h')

diff --git a/Source/JavaScriptCore/runtime/StringRecursionChecker.h b/Source/JavaScriptCore/runtime/StringRecursionChecker.h
new file mode 100644
index 000000000..0f1990e76
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/StringRecursionChecker.h
@@ -0,0 +1,97 @@
+/*
+ *  Copyright (C) 2011 Apple Inc. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef StringRecursionChecker_h
+#define StringRecursionChecker_h
+
+#include "Interpreter.h"
+#include <wtf/StackStats.h>
+#include <wtf/WTFThreadData.h>
+
+namespace JSC {
+
+class StringRecursionChecker {
+    WTF_MAKE_NONCOPYABLE(StringRecursionChecker);
+
+public:
+    StringRecursionChecker(ExecState*, JSObject* thisObject);
+    ~StringRecursionChecker();
+
+    JSValue earlyReturnValue() const; // 0 if everything is OK, value to return for failure cases
+
+private:
+    JSValue throwStackOverflowError();
+    JSValue emptyString();
+    JSValue performCheck();
+
+    ExecState* m_exec;
+    JSObject* m_thisObject;
+    JSValue m_earlyReturnValue;
+
+    StackStats::CheckPoint stackCheckpoint;
+};
+
+inline JSValue StringRecursionChecker::performCheck()
+{
+    VM& vm = m_exec->vm();
+    if (!vm.isSafeToRecurse())
+        return throwStackOverflowError();
+
+    bool alreadyVisited = false;
+    if (!vm.stringRecursionCheckFirstObject)
+        vm.stringRecursionCheckFirstObject = m_thisObject;
+    else if (vm.stringRecursionCheckFirstObject == m_thisObject)
+        alreadyVisited = true;
+    else
+        alreadyVisited = !vm.stringRecursionCheckVisitedObjects.add(m_thisObject).isNewEntry;
+
+    if (alreadyVisited)
+        return emptyString(); // Return empty string to avoid infinite recursion.
+    return JSValue(); // Indicate success.
+}
+
+inline StringRecursionChecker::StringRecursionChecker(ExecState* exec, JSObject* thisObject)
+    : m_exec(exec)
+    , m_thisObject(thisObject)
+    , m_earlyReturnValue(performCheck())
+{
+}
+
+inline JSValue StringRecursionChecker::earlyReturnValue() const
+{
+    return m_earlyReturnValue;
+}
+
+inline StringRecursionChecker::~StringRecursionChecker()
+{
+    if (m_earlyReturnValue)
+        return;
+
+    VM& vm = m_exec->vm();
+    if (vm.stringRecursionCheckFirstObject == m_thisObject)
+        vm.stringRecursionCheckFirstObject = nullptr;
+    else {
+        ASSERT(vm.stringRecursionCheckVisitedObjects.contains(m_thisObject));
+        vm.stringRecursionCheckVisitedObjects.remove(m_thisObject);
+    }
+}
+
+}
+
+#endif
-- 
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