1 /* 2 * Copyright (C) 2010 Apple Inc. All Rights Reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 */ 26 27 #ifndef StackBounds_h 28 #define StackBounds_h 29 30 namespace WTF { 31 32 class StackBounds { 33 // recursionCheck() / recursionLimit() tests (by default) 34 // that we are at least this far from the end of the stack. 35 const static size_t s_defaultAvailabilityDelta = 4096; 36 37 public: StackBounds()38 StackBounds() 39 : m_origin(0) 40 , m_bound(0) 41 { 42 } 43 currentThreadStackBounds()44 static StackBounds currentThreadStackBounds() 45 { 46 StackBounds bounds; 47 bounds.initialize(); 48 bounds.checkConsistency(); 49 return bounds; 50 } 51 origin()52 void* origin() const 53 { 54 ASSERT(m_origin); 55 return m_origin; 56 } 57 current()58 void* current() const 59 { 60 checkConsistency(); 61 void* currentPosition = ¤tPosition; 62 return currentPosition; 63 } 64 65 void* recursionLimit(size_t minAvailableDelta = s_defaultAvailabilityDelta) const 66 { 67 checkConsistency(); 68 return isGrowingDownward() 69 ? static_cast<char*>(m_bound) + minAvailableDelta 70 : static_cast<char*>(m_bound) - minAvailableDelta; 71 } 72 73 bool recursionCheck(size_t minAvailableDelta = s_defaultAvailabilityDelta) const 74 { 75 checkConsistency(); 76 return isGrowingDownward() 77 ? current() >= recursionLimit(minAvailableDelta) 78 : current() <= recursionLimit(minAvailableDelta); 79 } 80 81 private: 82 void initialize(); 83 84 isGrowingDownward()85 bool isGrowingDownward() const 86 { 87 ASSERT(m_origin && m_bound); 88 #if OS(WINCE) 89 return m_origin > m_bound; 90 #else 91 return true; 92 #endif 93 } 94 checkConsistency()95 void checkConsistency() const 96 { 97 #if !ASSERT_DISABLED 98 void* currentPosition = ¤tPosition; 99 ASSERT(m_origin != m_bound); 100 ASSERT(isGrowingDownward() 101 ? (currentPosition < m_origin && currentPosition > m_bound) 102 : (currentPosition > m_origin && currentPosition < m_bound)); 103 #endif 104 } 105 106 void* m_origin; 107 void* m_bound; 108 }; 109 110 } // namespace WTF 111 112 using WTF::StackBounds; 113 114 #endif 115