mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
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134 lines
4.9 KiB
C++
134 lines
4.9 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 file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef replace_malloc_bridge_h
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#define replace_malloc_bridge_h
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/*
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* The replace-malloc bridge allows bidirectional method calls between
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* a program and the replace-malloc library that has been loaded for it.
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* In Firefox, this is used to allow method calls between code in libxul
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* and code in the replace-malloc library, without libxul needing to link
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* against that library or vice-versa.
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*
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* Subsystems can add methods for their own need. Replace-malloc libraries
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* can decide to implement those methods or not.
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*
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* Replace-malloc libraries can provide such a bridge by implementing
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* a ReplaceMallocBridge-derived class, and a replace_get_bridge function
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* returning an instance of that class. The default methods in
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* ReplaceMallocBridge are expected to return values that callers would
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* understand as "the bridge doesn't implement this method", so that a
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* replace-malloc library doesn't have to implement all methods.
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*
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* The ReplaceMallocBridge class contains definitions for methods for
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* all replace-malloc libraries. Each library picks the methods it wants
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* to reply to in its ReplaceMallocBridge-derived class instance.
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* All methods of ReplaceMallocBridge must be virtual. Similarly,
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* anything passed as an argument to those methods must be plain data, or
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* an instance of a class with only virtual methods.
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*
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* Binary compatibility is expected to be maintained, such that a newer
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* Firefox can be used with an old replace-malloc library, or an old
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* Firefox can be used with a newer replace-malloc library. As such, only
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* new virtual methods should be added to ReplaceMallocBridge, and
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* each change should have a corresponding bump of the mVersion value.
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* At the same time, each virtual method should have a corresponding
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* wrapper calling the virtual method on the instance from
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* ReplaceMallocBridge::Get(), giving it the version the virtual method
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* was added.
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*
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* Parts that are not relevant to the replace-malloc library end of the
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* bridge are hidden when REPLACE_MALLOC_IMPL is not defined, which is
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* the case when including replace_malloc.h.
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*/
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struct ReplaceMallocBridge;
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#ifdef __cplusplus
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#include "mozilla/NullPtr.h"
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#include "mozilla/Types.h"
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#ifndef REPLACE_MALLOC_IMPL
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/* Returns the replace-malloc bridge if there is one to be returned. */
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extern "C" MFBT_API ReplaceMallocBridge* get_bridge();
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#endif
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namespace mozilla {
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namespace dmd {
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struct DMDFuncs;
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}
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/* Callbacks to register debug file handles for Poison IO interpose.
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* See Mozilla(|Un)RegisterDebugHandle in xpcom/build/PoisonIOInterposer.h */
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struct DebugFdRegistry
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{
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virtual void RegisterHandle(intptr_t aFd);
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virtual void UnRegisterHandle(intptr_t aFd);
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};
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} // namespace mozilla
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struct ReplaceMallocBridge
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{
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ReplaceMallocBridge() : mVersion(2) {}
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/* This method was added in version 1 of the bridge. */
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virtual mozilla::dmd::DMDFuncs* GetDMDFuncs() { return nullptr; }
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/* Send a DebugFdRegistry instance to the replace-malloc library so that
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* it can register/unregister file descriptors whenever needed. The
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* instance is valid until the process dies.
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* This method was added in version 2 of the bridge. */
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virtual void InitDebugFd(mozilla::DebugFdRegistry&) {}
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#ifndef REPLACE_MALLOC_IMPL
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/* Returns the replace-malloc bridge if its version is at least the
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* requested one. */
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static ReplaceMallocBridge* Get(int aMinimumVersion) {
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static ReplaceMallocBridge* sSingleton = get_bridge();
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return (sSingleton && sSingleton->mVersion >= aMinimumVersion)
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? sSingleton : nullptr;
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}
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#endif
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protected:
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const int mVersion;
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};
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#ifndef REPLACE_MALLOC_IMPL
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/* Class containing wrappers for calls to ReplaceMallocBridge methods.
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* Those wrappers need to be static methods in a class because compilers
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* complain about unused static global functions, and linkers complain
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* about multiple definitions of non-static global functions.
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* Using a separate class from ReplaceMallocBridge allows the function
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* names to be identical. */
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struct ReplaceMalloc
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{
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/* Don't call this method from performance critical code. Use
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* mozilla::dmd::DMDFuncs::Get() instead, it has less overhead. */
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static mozilla::dmd::DMDFuncs* GetDMDFuncs()
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{
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auto singleton = ReplaceMallocBridge::Get(/* minimumVersion */ 1);
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return singleton ? singleton->GetDMDFuncs() : nullptr;
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}
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static void InitDebugFd(mozilla::DebugFdRegistry& aRegistry)
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{
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auto singleton = ReplaceMallocBridge::Get(/* minimumVersion */ 2);
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if (singleton) {
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singleton->InitDebugFd(aRegistry);
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}
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}
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};
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#endif
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#endif /* __cplusplus */
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#endif /* replace_malloc_bridge_h */
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