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/*
* Copyright (C) 2015-2022 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 "JSCast.h"
#include "ScopeOffset.h"
#include "VM.h"
#include <wtf/Assertions.h>
#include <wtf/CagedUniquePtr.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
class WatchpointSet;
// This class's only job is to hold onto the list of ScopeOffsets for each argument that a
// function has. Most of the time, the BytecodeGenerator will create one of these and it will
// never be modified subsequently. There is a rare case where a ScopedArguments object is created
// and aliases one of these and then decides to modify it; in that case we do copy-on-write. This
// makes sense because such modifications are so uncommon. You'd have to do something crazy like
// "delete arguments[i]" or some variant of defineOwnProperty.
class ScopedArgumentsTable final : public JSCell {
friend class CachedScopedArgumentsTable;
public:
using Base = JSCell;
static constexpr unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
static constexpr DestructionMode needsDestruction = NeedsDestruction;
template<typename CellType, SubspaceAccess mode>
static GCClient::IsoSubspace* subspaceFor(VM& vm)
{
return vm.scopedArgumentsTableSpace<mode>();
}
private:
ScopedArgumentsTable(VM&);
~ScopedArgumentsTable();
public:
static ScopedArgumentsTable* create(VM&);
static ScopedArgumentsTable* tryCreate(VM&, uint32_t length);
static void destroy(JSCell*);
uint32_t length() const { return m_length; }
ScopedArgumentsTable* trySetLength(VM&, uint32_t newLength);
ScopeOffset get(uint32_t i) const { return at(i); }
WatchpointSet* getWatchpointSet(uint32_t i) const { return m_watchpointSets.at(i); }
void lock()
{
m_locked = true;
}
ScopedArgumentsTable* trySet(VM&, uint32_t index, ScopeOffset);
void trySetWatchpointSet(uint32_t index, WatchpointSet* watchpoints);
void clearWatchpointSet(uint32_t index) { m_watchpointSets[index] = nullptr; }
DECLARE_INFO;
static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
static constexpr ptrdiff_t offsetOfLength() { return OBJECT_OFFSETOF(ScopedArgumentsTable, m_length); }
static constexpr ptrdiff_t offsetOfArguments() { return OBJECT_OFFSETOF(ScopedArgumentsTable, m_arguments); }
typedef CagedUniquePtr<Gigacage::Primitive, ScopeOffset> ArgumentsPtr;
private:
ScopedArgumentsTable* tryClone(VM&);
ScopeOffset& at(uint32_t i) const
{
ASSERT_WITH_SECURITY_IMPLICATION(i < m_length);
return m_arguments.get()[i];
}
uint32_t m_length;
bool m_locked; // Being locked means that there are multiple references to this object and none of them expect to see the others' modifications. This means that modifications need to make a copy first.
ArgumentsPtr m_arguments;
Vector<WatchpointSet*> m_watchpointSets;
};
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
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