| /* |
| * Copyright (C) 2017-2020 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include <wtf/ForbidHeapAllocation.h> |
| |
| namespace JSC { |
| |
| class VM; |
| |
| // The only reason we implement DisallowVMEntry as specialization of a template |
| // is so that we can work around having to #include VM.h, which can hurt build |
| // time. This defers the cost of #include'ing VM.h to only the clients that |
| // need it. |
| |
| template<typename VMType = VM> |
| class DisallowVMEntryImpl { |
| WTF_FORBID_HEAP_ALLOCATION; |
| public: |
| DisallowVMEntryImpl(VMType& vm) |
| : m_vm(&vm) |
| { |
| m_vm->disallowVMEntryCount++; |
| } |
| |
| DisallowVMEntryImpl(const DisallowVMEntryImpl& other) |
| : m_vm(other.m_vm) |
| { |
| m_vm->disallowVMEntryCount++; |
| } |
| |
| ~DisallowVMEntryImpl() |
| { |
| RELEASE_ASSERT(m_vm->disallowVMEntryCount); |
| m_vm->disallowVMEntryCount--; |
| m_vm = nullptr; |
| } |
| |
| DisallowVMEntryImpl& operator=(const DisallowVMEntryImpl& other) |
| { |
| RELEASE_ASSERT(m_vm && m_vm == other.m_vm); |
| RELEASE_ASSERT(m_vm->disallowVMEntryCount); |
| // Conceptually, we need to decrement the disallowVMEntryCount of the |
| // old m_vm, and increment the disallowVMEntryCount of the new m_vm. |
| // But since the old and the new m_vm should always be the same, the |
| // decrementing and incrementing cancels out, and there's nothing more |
| // to do here. |
| return *this; |
| } |
| |
| private: |
| VMType* m_vm; |
| }; |
| |
| using DisallowVMEntry = DisallowVMEntryImpl<VM>; |
| |
| } // namespace JSC |