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Everywhere: Prevent risky implicit casts of (Nonnull)RefPtr

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Our existing implementation did not check the element type of the other
pointer in the constructors and move assignment operators. This meant
that some operations that would require explicit casting on raw pointers
were done implicitly, such as:
- downcasting a base class to a derived class (e.g. `Kernel::Inode` =>
  `Kernel::ProcFSDirectoryInode` in Kernel/ProcFS.cpp),
- casting to an unrelated type (e.g. `Promise<bool>` => `Promise<Empty>`
  in LibIMAP/Client.cpp)

This, of course, allows gross violations of the type system, and makes
the need to type-check less obvious before downcasting. Luckily, while
adding the `static_ptr_cast`s, only two truly incorrect usages were
found; in the other instances, our casts just needed to be made
explicit.
This commit is contained in:
Daniel Bertalan 2021-09-03 19:11:51 +02:00 • committed by Andreas Kling
parent bad23e3f8c
commit d7b6cc6421
21 changed files with 43 additions and 43 deletions
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20
AK/RefPtr.h
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@ -154,18 +154,18 @@ public:
{
}
template<typename U>
ALWAYS_INLINE RefPtr(const NonnullRefPtr<U>& other)
ALWAYS_INLINE RefPtr(const NonnullRefPtr<U>& other) requires(IsConvertible<U*, T*>)
: m_bits(PtrTraits::as_bits(const_cast<U*>(other.add_ref())))
{
}
template<typename U>
ALWAYS_INLINE RefPtr(NonnullRefPtr<U>&& other)
ALWAYS_INLINE RefPtr(NonnullRefPtr<U>&& other) requires(IsConvertible<U*, T*>)
: m_bits(PtrTraits::as_bits(&other.leak_ref()))
{
VERIFY(!is_null());
}
template<typename U, typename P = RefPtrTraits<U>>
RefPtr(RefPtr<U, P>&& other)
RefPtr(RefPtr<U, P>&& other) requires(IsConvertible<U*, T*>)
: m_bits(PtrTraits::template convert_from<U, P>(other.leak_ref_raw()))
{
}
@ -174,7 +174,7 @@ public:
{
}
template<typename U, typename P = RefPtrTraits<U>>
RefPtr(const RefPtr<U, P>& other)
RefPtr(const RefPtr<U, P>& other) requires(IsConvertible<U*, T*>)
: m_bits(other.add_ref_raw())
{
}
@ -203,7 +203,7 @@ public:
}
template<typename U, typename P = RefPtrTraits<U>>
void swap(RefPtr<U, P>& other)
void swap(RefPtr<U, P>& other) requires(IsConvertible<U*, T*>)
{
// NOTE: swap is not atomic!
FlatPtr other_bits = P::exchange(other.m_bits, P::default_null_value);
@ -219,14 +219,14 @@ public:
}
template<typename U, typename P = RefPtrTraits<U>>
ALWAYS_INLINE RefPtr& operator=(RefPtr<U, P>&& other)
ALWAYS_INLINE RefPtr& operator=(RefPtr<U, P>&& other) requires(IsConvertible<U*, T*>)
{
assign_raw(PtrTraits::template convert_from<U, P>(other.leak_ref_raw()));
return *this;
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<U>&& other)
ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<U>&& other) requires(IsConvertible<U*, T*>)
{
assign_raw(PtrTraits::as_bits(&other.leak_ref()));
return *this;
@ -239,7 +239,7 @@ public:
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(const NonnullRefPtr<U>& other)
ALWAYS_INLINE RefPtr& operator=(const NonnullRefPtr<U>& other) requires(IsConvertible<U*, T*>)
{
assign_raw(PtrTraits::as_bits(other.add_ref()));
return *this;
@ -253,7 +253,7 @@ public:
}
template<typename U>
ALWAYS_INLINE RefPtr& operator=(const RefPtr<U>& other)
ALWAYS_INLINE RefPtr& operator=(const RefPtr<U>& other) requires(IsConvertible<U*, T*>)
{
assign_raw(other.add_ref_raw());
return *this;
@ -470,7 +470,7 @@ inline RefPtr<T> static_ptr_cast(const RefPtr<U>& ptr)
}
template<typename T, typename PtrTraitsT, typename U, typename PtrTraitsU>
inline void swap(RefPtr<T, PtrTraitsT>& a, RefPtr<U, PtrTraitsU>& b)
inline void swap(RefPtr<T, PtrTraitsT>& a, RefPtr<U, PtrTraitsU>& b) requires(IsConvertible<U*, T*>)
{
a.swap(b);
}