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257d9118dc
Right now, NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR expects singleton constructors to return already-addrefed raw pointers, and while it accepts constructors that return already_AddRefed, most existing don't do so. Meanwhile, the convention elsewhere is that a raw pointer return value is owned by the callee, and that the caller needs to addref it if it wants to keep its own reference to it. The difference in convention makes it easy to leak (I've definitely caused more than one shutdown leak this way), so it would be better if we required the singleton getters to return an explicit already_AddRefed, which would behave the same for all callers. This also cleans up several singleton constructors that left a dangling pointer to their singletons when their initialization methods failed, when they released their references without clearing their global raw pointers. MozReview-Commit-ID: 9peyG4pRYcr --HG-- extra : rebase_source : 2f5bd89c17cb554541be38444672a827c1392f3f
96 lines
5.3 KiB
C++
96 lines
5.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_GenericModule_h
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#define mozilla_GenericModule_h
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#include "mozilla/Attributes.h"
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#include "mozilla/Module.h"
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#define NS_GENERIC_FACTORY_CONSTRUCTOR(_InstanceClass) \
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static nsresult \
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_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, \
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void **aResult) \
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{ \
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RefPtr<_InstanceClass> inst; \
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\
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*aResult = nullptr; \
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if (nullptr != aOuter) { \
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return NS_ERROR_NO_AGGREGATION; \
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} \
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\
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inst = new _InstanceClass(); \
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return inst->QueryInterface(aIID, aResult); \
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}
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#define NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod) \
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static nsresult \
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_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, \
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void **aResult) \
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{ \
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nsresult rv; \
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\
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RefPtr<_InstanceClass> inst; \
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\
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*aResult = nullptr; \
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if (nullptr != aOuter) { \
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return NS_ERROR_NO_AGGREGATION; \
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} \
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\
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inst = new _InstanceClass(); \
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rv = inst->_InitMethod(); \
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if (NS_SUCCEEDED(rv)) { \
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rv = inst->QueryInterface(aIID, aResult); \
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} \
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\
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return rv; \
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}
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namespace mozilla {
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namespace detail {
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template<typename T>
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struct RemoveAlreadyAddRefed
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{
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using Type = T;
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};
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template<typename T>
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struct RemoveAlreadyAddRefed<already_AddRefed<T>>
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{
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using Type = T;
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};
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} // namespace detail
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} // namespace mozilla
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// 'Constructor' that uses an existing getter function that gets a singleton.
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#define NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(_InstanceClass, _GetterProc) \
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static nsresult \
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_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, \
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void **aResult) \
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{ \
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RefPtr<_InstanceClass> inst; \
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\
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*aResult = nullptr; \
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if (nullptr != aOuter) { \
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return NS_ERROR_NO_AGGREGATION; \
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} \
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\
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using T = mozilla::detail::RemoveAlreadyAddRefed<decltype(_GetterProc())>::Type; \
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static_assert(mozilla::IsSame<already_AddRefed<T>, decltype(_GetterProc())>::value, \
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"Singleton constructor must return already_AddRefed"); \
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static_assert(mozilla::IsBaseOf<_InstanceClass, T>::value, \
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"Singleton constructor must return correct already_AddRefed");\
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inst = _GetterProc(); \
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if (nullptr == inst) { \
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return NS_ERROR_OUT_OF_MEMORY; \
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} \
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return inst->QueryInterface(aIID, aResult); \
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}
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#endif // mozilla_GenericModule_h
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