ladybird/AK/RefPtr.h
Andreas Kling b7e847e58b AK: Fix crash during teardown of self-owning objects
We now null out smart pointers *before* calling unref on the pointee.
This ensures that the same smart pointer can't be used to acquire a new
reference to the pointee after its destruction has begun.

I ran into this when destroying a non-empty IntrusiveList of RefPtrs,
but the problem was more general so this fixes it for all of RefPtr,
NonnullRefPtr, OwnPtr and NonnullOwnPtr.
2023-04-21 18:15:00 +02:00

338 lines
7.1 KiB
C++

/*
* Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#define REFPTR_SCRUB_BYTE 0xe0
#include <AK/Assertions.h>
#include <AK/Atomic.h>
#include <AK/Error.h>
#include <AK/Format.h>
#include <AK/Forward.h>
#include <AK/NonnullRefPtr.h>
#include <AK/StdLibExtras.h>
#include <AK/Traits.h>
#include <AK/Types.h>
namespace AK {
template<typename T>
class [[nodiscard]] RefPtr {
template<typename U>
friend class RefPtr;
template<typename U>
friend class WeakPtr;
template<typename U>
friend class NonnullRefPtr;
public:
enum AdoptTag {
Adopt
};
RefPtr() = default;
RefPtr(T const* ptr)
: m_ptr(const_cast<T*>(ptr))
{
ref_if_not_null(m_ptr);
}
RefPtr(T const& object)
: m_ptr(const_cast<T*>(&object))
{
m_ptr->ref();
}
RefPtr(AdoptTag, T& object)
: m_ptr(&object)
{
}
RefPtr(RefPtr&& other)
: m_ptr(other.leak_ref())
{
}
ALWAYS_INLINE RefPtr(NonnullRefPtr<T> const& other)
: m_ptr(const_cast<T*>(other.ptr()))
{
m_ptr->ref();
}
template<typename U>
ALWAYS_INLINE RefPtr(NonnullRefPtr<U> const& other)
requires(IsConvertible<U*, T*>)
: m_ptr(const_cast<T*>(static_cast<T const*>(other.ptr())))
{
m_ptr->ref();
}
template<typename U>
ALWAYS_INLINE RefPtr(NonnullRefPtr<U>&& other)
requires(IsConvertible<U*, T*>)
: m_ptr(static_cast<T*>(&other.leak_ref()))
{
}
template<typename U>
RefPtr(RefPtr<U>&& other)
requires(IsConvertible<U*, T*>)
: m_ptr(static_cast<T*>(other.leak_ref()))
{
}
RefPtr(RefPtr const& other)
: m_ptr(other.m_ptr)
{
ref_if_not_null(m_ptr);
}
template<typename U>
RefPtr(RefPtr<U> const& other)
requires(IsConvertible<U*, T*>)
: m_ptr(const_cast<T*>(static_cast<T const*>(other.ptr())))
{
ref_if_not_null(m_ptr);
}
ALWAYS_INLINE ~RefPtr()
{
clear();
#ifdef SANITIZE_PTRS
m_ptr = reinterpret_cast<T*>(explode_byte(REFPTR_SCRUB_BYTE));
#endif
}
template<typename U>
RefPtr(OwnPtr<U> const&) = delete;
template<typename U>
RefPtr& operator=(OwnPtr<U> const&) = delete;
void swap(RefPtr& other)
{
AK::swap(m_ptr, other.m_ptr);
}
template<typename U>
void swap(RefPtr<U>& other)
requires(IsConvertible<U*, T*>)
{
AK::swap(m_ptr, other.m_ptr);
}
ALWAYS_INLINE RefPtr& operator=(RefPtr&& other)
{
RefPtr tmp { move(other) };
swap(tmp);
return *this;
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(RefPtr<U>&& other)
requires(IsConvertible<U*, T*>)
{
RefPtr tmp { move(other) };
swap(tmp);
return *this;
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<U>&& other)
requires(IsConvertible<U*, T*>)
{
RefPtr tmp { move(other) };
swap(tmp);
return *this;
}
ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<T> const& other)
{
RefPtr tmp { other };
swap(tmp);
return *this;
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<U> const& other)
requires(IsConvertible<U*, T*>)
{
RefPtr tmp { other };
swap(tmp);
return *this;
}
ALWAYS_INLINE RefPtr& operator=(RefPtr const& other)
{
RefPtr tmp { other };
swap(tmp);
return *this;
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(RefPtr<U> const& other)
requires(IsConvertible<U*, T*>)
{
RefPtr tmp { other };
swap(tmp);
return *this;
}
ALWAYS_INLINE RefPtr& operator=(T const* ptr)
{
RefPtr tmp { ptr };
swap(tmp);
return *this;
}
ALWAYS_INLINE RefPtr& operator=(T const& object)
{
RefPtr tmp { object };
swap(tmp);
return *this;
}
RefPtr& operator=(nullptr_t)
{
clear();
return *this;
}
ALWAYS_INLINE bool assign_if_null(RefPtr&& other)
{
if (this == &other)
return is_null();
*this = move(other);
return true;
}
template<typename U>
ALWAYS_INLINE bool assign_if_null(RefPtr<U>&& other)
{
if (this == &other)
return is_null();
*this = move(other);
return true;
}
ALWAYS_INLINE void clear()
{
auto* ptr = exchange(m_ptr, nullptr);
unref_if_not_null(ptr);
}
bool operator!() const { return !m_ptr; }
[[nodiscard]] T* leak_ref()
{
return exchange(m_ptr, nullptr);
}
NonnullRefPtr<T> release_nonnull()
{
auto* ptr = leak_ref();
VERIFY(ptr);
return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *ptr);
}
ALWAYS_INLINE T* ptr() const { return as_ptr(); }
ALWAYS_INLINE T* operator->() const
{
return as_nonnull_ptr();
}
ALWAYS_INLINE T& operator*() const
{
return *as_nonnull_ptr();
}
ALWAYS_INLINE operator T*() const { return as_ptr(); }
ALWAYS_INLINE operator bool() { return !is_null(); }
bool operator==(nullptr_t) const { return is_null(); }
bool operator==(RefPtr const& other) const { return as_ptr() == other.as_ptr(); }
template<typename U>
bool operator==(NonnullRefPtr<U> const& other) const { return as_ptr() == other.m_ptr; }
template<typename RawPtr>
bool operator==(RawPtr other) const
requires(IsPointer<RawPtr>)
{
return as_ptr() == other;
}
ALWAYS_INLINE bool is_null() const { return !m_ptr; }
private:
ALWAYS_INLINE T* as_ptr() const
{
return m_ptr;
}
ALWAYS_INLINE T* as_nonnull_ptr() const
{
VERIFY(m_ptr);
return m_ptr;
}
T* m_ptr { nullptr };
};
template<typename T>
struct Formatter<RefPtr<T>> : Formatter<T const*> {
ErrorOr<void> format(FormatBuilder& builder, RefPtr<T> const& value)
{
return Formatter<T const*>::format(builder, value.ptr());
}
};
template<typename T>
struct Traits<RefPtr<T>> : public GenericTraits<RefPtr<T>> {
using PeekType = T*;
using ConstPeekType = T const*;
static unsigned hash(RefPtr<T> const& p) { return ptr_hash(p.ptr()); }
static bool equals(RefPtr<T> const& a, RefPtr<T> const& b) { return a.ptr() == b.ptr(); }
};
template<typename T, typename U>
inline NonnullRefPtr<T> static_ptr_cast(NonnullRefPtr<U> const& ptr)
{
return NonnullRefPtr<T>(static_cast<T const&>(*ptr));
}
template<typename T, typename U>
inline RefPtr<T> static_ptr_cast(RefPtr<U> const& ptr)
{
return RefPtr<T>(static_cast<T const*>(ptr.ptr()));
}
template<typename T, typename U>
inline void swap(RefPtr<T>& a, RefPtr<U>& b)
requires(IsConvertible<U*, T*>)
{
a.swap(b);
}
template<typename T>
inline RefPtr<T> adopt_ref_if_nonnull(T* object)
{
if (object)
return RefPtr<T>(RefPtr<T>::Adopt, *object);
return {};
}
}
#if USING_AK_GLOBALLY
using AK::adopt_ref_if_nonnull;
using AK::RefPtr;
using AK::static_ptr_cast;
#endif