Revision 58d7af37f45f88130641188b1e39b00569acd575 authored by T. Foley on 06 June 2021, 15:59:28 UTC, committed by GitHub on 06 June 2021, 15:59:28 UTC
* Fix a bug in preprocessor "busy" logic This bug manifested in both incorrect preprocessor output for certain complicated cases, and also (more importantly) a use-after-free issue. One of the "clever" design choices in the Slang preprocessor implementation is that the set of "busy" macros during expansion is implicitly defined by a linked list of those invocations that are actively being read from as part of the input stack. This logic works very well for checking whether a macro name is busy before triggering expansion, and for computing what macros should be considered busy during expansion of an object-like macro. The problem case here was with function-like macros where the preprocessor was re-using the same list of busy macros that had been fetched when reading the macro name, but doing so *after* all the macro argument tokens had been read. Because additional tokens had been read from the input stream stack, there was no guarantee that the invocations that had been active before were still live. The new logic computes the set of busy macros fresh before starting expansion of a function-like macro invocation. A test is included to ensure that the case that showed the use-after-free bug has been fixed. In addition, the new logic is careful to compute the busy macros only based on where subsequent tokens will come from and not based on any macros that might have contributed to the argument tokens themselves. A test case has been added that relies on getting this detail correct. * Update slang-preprocessor.cpp Remove a test typo. Co-authored-by: jsmall-nvidia <jsmall@nvidia.com>
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slang-com-ptr.h
#ifndef SLANG_COM_PTR_H
#define SLANG_COM_PTR_H
#include "slang-com-helper.h"
#include <assert.h>
#include <cstddef>
namespace Slang {
/*! \brief ComPtr is a simple smart pointer that manages types which implement COM based interfaces.
\details A class that implements a COM, must derive from the IUnknown interface or a type that matches
it's layout exactly (such as ISlangUnknown). Trying to use this template with a class that doesn't follow
these rules, will lead to undefined behavior.
This is a 'strong' pointer type, and will AddRef when a non null pointer is set and Release when the pointer
leaves scope.
Using 'detach' allows a pointer to be removed from the management of the ComPtr.
To set the smart pointer to null, there is the method setNull, or alternatively just assign SLANG_NULL/nullptr.
One edge case using the template is that sometimes you want access as a pointer to a pointer. Sometimes this
is to write into the smart pointer, other times to pass as an array. To handle these different behaviors
there are the methods readRef and writeRef, which are used instead of the & (ref) operator. For example
\code
Void doSomething(ID3D12Resource** resources, IndexT numResources);
// ...
ComPtr<ID3D12Resource> resources[3];
doSomething(resources[0].readRef(), SLANG_COUNT_OF(resource));
\endcode
A more common scenario writing to the pointer
\code
IUnknown* unk = ...;
ComPtr<ID3D12Resource> resource;
Result res = unk->QueryInterface(resource.writeRef());
\endcode
*/
// Enum to force initializing as an attach (without adding a reference)
enum InitAttach
{
INIT_ATTACH
};
template <class T>
class ComPtr
{
public:
typedef T Type;
typedef ComPtr ThisType;
typedef ISlangUnknown* Ptr;
/// Constructors
/// Default Ctor. Sets to nullptr
SLANG_FORCE_INLINE ComPtr() :m_ptr(nullptr) {}
SLANG_FORCE_INLINE ComPtr(std::nullptr_t) : m_ptr(nullptr) {}
/// Sets, and ref counts.
SLANG_FORCE_INLINE explicit ComPtr(T* ptr) :m_ptr(ptr) { if (ptr) ((Ptr)ptr)->addRef(); }
/// The copy ctor
SLANG_FORCE_INLINE ComPtr(const ThisType& rhs) : m_ptr(rhs.m_ptr) { if (m_ptr) ((Ptr)m_ptr)->addRef(); }
/// Ctor without adding to ref count.
SLANG_FORCE_INLINE explicit ComPtr(InitAttach, T* ptr) :m_ptr(ptr) { }
/// Ctor without adding to ref count
SLANG_FORCE_INLINE ComPtr(InitAttach, const ThisType& rhs) : m_ptr(rhs.m_ptr) { }
#ifdef SLANG_HAS_MOVE_SEMANTICS
/// Move Ctor
SLANG_FORCE_INLINE ComPtr(ThisType&& rhs) : m_ptr(rhs.m_ptr) { rhs.m_ptr = nullptr; }
/// Move assign
SLANG_FORCE_INLINE ComPtr& operator=(ThisType&& rhs) { T* swap = m_ptr; m_ptr = rhs.m_ptr; rhs.m_ptr = swap; return *this; }
#endif
/// Destructor releases the pointer, assuming it is set
SLANG_FORCE_INLINE ~ComPtr() { if (m_ptr) ((Ptr)m_ptr)->release(); }
// !!! Operators !!!
/// Returns the dumb pointer
SLANG_FORCE_INLINE operator T *() const { return m_ptr; }
SLANG_FORCE_INLINE T& operator*() { return *m_ptr; }
/// For making method invocations through the smart pointer work through the dumb pointer
SLANG_FORCE_INLINE T* operator->() const { return m_ptr; }
/// Assign
SLANG_FORCE_INLINE const ThisType &operator=(const ThisType& rhs);
/// Assign from dumb ptr
SLANG_FORCE_INLINE T* operator=(T* in);
/// Get the pointer and don't ref
SLANG_FORCE_INLINE T* get() const { return m_ptr; }
/// Release a contained nullptr pointer if set
SLANG_FORCE_INLINE void setNull();
/// Detach
SLANG_FORCE_INLINE T* detach() { T* ptr = m_ptr; m_ptr = nullptr; return ptr; }
/// Set to a pointer without changing the ref count
SLANG_FORCE_INLINE void attach(T* in) { m_ptr = in; }
/// Get ready for writing (nulls contents)
SLANG_FORCE_INLINE T** writeRef() { setNull(); return &m_ptr; }
/// Get for read access
SLANG_FORCE_INLINE T*const* readRef() const { return &m_ptr; }
/// Swap
void swap(ThisType& rhs);
protected:
/// Gets the address of the dumb pointer.
// Disabled: use writeRef and readRef to get a reference based on usage.
SLANG_FORCE_INLINE T** operator&() = delete;
T* m_ptr;
};
//----------------------------------------------------------------------------
template <typename T>
void ComPtr<T>::setNull()
{
if (m_ptr)
{
((Ptr)m_ptr)->release();
m_ptr = nullptr;
}
}
//----------------------------------------------------------------------------
template <typename T>
const ComPtr<T>& ComPtr<T>::operator=(const ThisType& rhs)
{
if (rhs.m_ptr) ((Ptr)rhs.m_ptr)->addRef();
if (m_ptr) ((Ptr)m_ptr)->release();
m_ptr = rhs.m_ptr;
return *this;
}
//----------------------------------------------------------------------------
template <typename T>
T* ComPtr<T>::operator=(T* ptr)
{
if (ptr) ((Ptr)ptr)->addRef();
if (m_ptr) ((Ptr)m_ptr)->release();
m_ptr = ptr;
return m_ptr;
}
//----------------------------------------------------------------------------
template <typename T>
void ComPtr<T>::swap(ThisType& rhs)
{
T* tmp = m_ptr;
m_ptr = rhs.m_ptr;
rhs.m_ptr = tmp;
}
} // namespace Slang
#endif // SLANG_COM_PTR_H
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