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https://github.com/LadybirdBrowser/ladybird
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b9ec043b5a
Maintain a HashTable<HeapBlock*> of live heap blocks in the Heap, updated on block creation and destruction. Weak containers (WeakMap, WeakSet, WeakRef, FinalizationRegistry) now check block liveness before accessing cell memory in their remove_dead_cells() methods. This prevents use-after-free when blocks have been freed during incremental sweeping.
84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
/*
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* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGC/HeapBlock.h>
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#include <LibJS/Runtime/ExternalMemory.h>
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#include <LibJS/Runtime/WeakMap.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(WeakMap);
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GC::Ref<WeakMap> WeakMap::create(Realm& realm)
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{
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return realm.create<WeakMap>(realm.intrinsics().weak_map_prototype());
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}
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WeakMap::WeakMap(Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, WeakContainer(heap())
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{
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}
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Optional<Value> WeakMap::weak_map_get(GC::Ptr<Cell> key) const
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{
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if (auto it = m_values.find(key); it != m_values.end())
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return it->value;
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return {};
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}
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bool WeakMap::weak_map_has(GC::Ptr<Cell> key) const
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{
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return m_values.contains(key);
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}
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void WeakMap::weak_map_set(GC::Ptr<Cell> key, Value value)
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{
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auto old_external_memory_size = external_memory_size();
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m_values.set(key, value);
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account_external_memory_change(old_external_memory_size);
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}
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bool WeakMap::weak_map_remove(GC::Ptr<Cell> key)
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{
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auto old_external_memory_size = external_memory_size();
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auto did_remove = m_values.remove(key);
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if (did_remove)
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account_external_memory_change(old_external_memory_size);
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return did_remove;
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}
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void WeakMap::remove_dead_cells(Badge<GC::Heap>)
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{
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m_values.remove_all_matching([this](Cell* key, Value) {
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auto* block = GC::HeapBlock::from_cell(key);
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return !heap().is_live_heap_block(block) || key->state() != Cell::State::Live || !key->is_marked();
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});
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}
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size_t WeakMap::external_memory_size() const
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{
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return saturating_add_external_memory_size(Object::external_memory_size(), hash_map_external_memory_size(m_values));
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}
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void WeakMap::account_external_memory_change(size_t old_external_memory_size)
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{
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auto new_external_memory_size = external_memory_size();
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if (new_external_memory_size > old_external_memory_size)
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heap().did_allocate_external_memory(new_external_memory_size - old_external_memory_size);
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else if (old_external_memory_size > new_external_memory_size)
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heap().did_free_external_memory(old_external_memory_size - new_external_memory_size);
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}
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void WeakMap::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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for (auto& entry : m_values)
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visitor.visit(entry.value);
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}
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}
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