1 /* 2 * Copyright (C) 2011 Apple Inc. All rights reserved. 3 * 4 * This library is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Lesser General Public 6 * License as published by the Free Software Foundation; either 7 * version 2 of the License, or (at your option) any later version. 8 * 9 * This library is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Lesser General Public License for more details. 13 * 14 * You should have received a copy of the GNU Lesser General Public 15 * License along with this library; if not, write to the Free Software 16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 17 * 18 */ 19 20 #ifndef StringRecursionChecker_h 21 #define StringRecursionChecker_h 22 23 #include "Interpreter.h" 24 25 namespace JSC { 26 27 class StringRecursionChecker { 28 WTF_MAKE_NONCOPYABLE(StringRecursionChecker); 29 30 public: 31 StringRecursionChecker(ExecState*, JSObject* thisObject); 32 ~StringRecursionChecker(); 33 34 EncodedJSValue earlyReturnValue() const; // 0 if everything is OK, value to return for failure cases 35 36 private: 37 EncodedJSValue throwStackOverflowError(); 38 EncodedJSValue emptyString(); 39 EncodedJSValue performCheck(); 40 41 ExecState* m_exec; 42 JSObject* m_thisObject; 43 EncodedJSValue m_earlyReturnValue; 44 }; 45 46 inline EncodedJSValue StringRecursionChecker::performCheck() 47 { 48 int size = m_exec->globalData().stringRecursionCheckVisitedObjects.size(); 49 if (size >= MaxSmallThreadReentryDepth && size >= m_exec->globalData().maxReentryDepth) 50 return throwStackOverflowError(); 51 bool alreadyVisited = !m_exec->globalData().stringRecursionCheckVisitedObjects.add(m_thisObject).second; 52 if (alreadyVisited) 53 return emptyString(); // Return empty string to avoid infinite recursion. 54 return 0; // Indicate success. 55 } 56 57 inline StringRecursionChecker::StringRecursionChecker(ExecState* exec, JSObject* thisObject) 58 : m_exec(exec) 59 , m_thisObject(thisObject) 60 , m_earlyReturnValue(performCheck()) 61 { 62 } 63 64 inline EncodedJSValue StringRecursionChecker::earlyReturnValue() const 65 { 66 return m_earlyReturnValue; 67 } 68 69 inline StringRecursionChecker::~StringRecursionChecker() 70 { 71 if (m_earlyReturnValue) 72 return; 73 ASSERT(m_exec->globalData().stringRecursionCheckVisitedObjects.contains(m_thisObject)); 74 m_exec->globalData().stringRecursionCheckVisitedObjects.remove(m_thisObject); 75 } 76 77 } 78 79 #endif 80
