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0d71623b50
If we are running a background thread in the launcher process to log failures, then allowing the main thread to proceed with monkeypatching system calls is a Bad Idea. This patch gives us an environment variable that, when set, indicates that it is unsafe for PoisonIOInterposer to run. This scenario is an uncommon one, but one that we must account for nonetheless. Differential Revision: https://phabricator.services.mozilla.com/D21607 --HG-- extra : moz-landing-system : lando
525 lines
16 KiB
C++
525 lines
16 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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#include <algorithm>
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#include <vector>
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#include "IOInterposer.h"
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#include "IOInterposerPrivate.h"
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#include "MainThreadIOLogger.h"
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#include "mozilla/Atomics.h"
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#include "mozilla/Mutex.h"
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#include "mozilla/RefPtr.h"
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#include "mozilla/StaticPtr.h"
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#include "mozilla/ThreadLocal.h"
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#include "nscore.h" // for NS_FREE_PERMANENT_DATA
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#if !defined(XP_WIN)
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# include "NSPRInterposer.h"
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#endif // !defined(XP_WIN)
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#include "nsXULAppAPI.h"
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#include "PoisonIOInterposer.h"
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#include "prenv.h"
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using namespace mozilla;
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namespace {
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/** Find if a vector contains a specific element */
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template <class T>
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bool VectorContains(const std::vector<T>& aVector, const T& aElement) {
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return std::find(aVector.begin(), aVector.end(), aElement) != aVector.end();
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}
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/** Remove element from a vector */
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template <class T>
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void VectorRemove(std::vector<T>& aVector, const T& aElement) {
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typename std::vector<T>::iterator newEnd =
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std::remove(aVector.begin(), aVector.end(), aElement);
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aVector.erase(newEnd, aVector.end());
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}
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/** Lists of Observers */
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struct ObserverLists {
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private:
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~ObserverLists() {}
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public:
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NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ObserverLists)
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ObserverLists() {}
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ObserverLists(ObserverLists const& aOther)
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: mCreateObservers(aOther.mCreateObservers),
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mReadObservers(aOther.mReadObservers),
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mWriteObservers(aOther.mWriteObservers),
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mFSyncObservers(aOther.mFSyncObservers),
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mStatObservers(aOther.mStatObservers),
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mCloseObservers(aOther.mCloseObservers),
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mStageObservers(aOther.mStageObservers) {}
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// Lists of observers for I/O events.
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// These are implemented as vectors since they are allowed to survive gecko,
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// without reporting leaks. This is necessary for the IOInterposer to be used
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// for late-write checks.
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std::vector<IOInterposeObserver*> mCreateObservers;
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std::vector<IOInterposeObserver*> mReadObservers;
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std::vector<IOInterposeObserver*> mWriteObservers;
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std::vector<IOInterposeObserver*> mFSyncObservers;
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std::vector<IOInterposeObserver*> mStatObservers;
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std::vector<IOInterposeObserver*> mCloseObservers;
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std::vector<IOInterposeObserver*> mStageObservers;
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};
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class PerThreadData {
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public:
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explicit PerThreadData(bool aIsMainThread = false)
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: mIsMainThread(aIsMainThread),
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mIsHandlingObservation(false),
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mCurrentGeneration(0) {
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MOZ_COUNT_CTOR(PerThreadData);
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}
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~PerThreadData() { MOZ_COUNT_DTOR(PerThreadData); }
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void CallObservers(IOInterposeObserver::Observation& aObservation) {
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// Prevent recursive reporting.
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if (mIsHandlingObservation) {
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return;
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}
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mIsHandlingObservation = true;
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// Decide which list of observers to inform
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std::vector<IOInterposeObserver*>* observers = nullptr;
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switch (aObservation.ObservedOperation()) {
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case IOInterposeObserver::OpCreateOrOpen:
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observers = &mObserverLists->mCreateObservers;
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break;
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case IOInterposeObserver::OpRead:
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observers = &mObserverLists->mReadObservers;
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break;
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case IOInterposeObserver::OpWrite:
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observers = &mObserverLists->mWriteObservers;
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break;
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case IOInterposeObserver::OpFSync:
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observers = &mObserverLists->mFSyncObservers;
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break;
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case IOInterposeObserver::OpStat:
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observers = &mObserverLists->mStatObservers;
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break;
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case IOInterposeObserver::OpClose:
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observers = &mObserverLists->mCloseObservers;
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break;
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case IOInterposeObserver::OpNextStage:
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observers = &mObserverLists->mStageObservers;
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break;
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default: {
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// Invalid IO operation, see documentation comment for
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// IOInterposer::Report()
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MOZ_ASSERT(false);
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// Just ignore it in non-debug builds.
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return;
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}
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}
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MOZ_ASSERT(observers);
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// Inform observers
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for (auto i = observers->begin(), e = observers->end(); i != e; ++i) {
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(*i)->Observe(aObservation);
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}
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mIsHandlingObservation = false;
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}
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inline uint32_t GetCurrentGeneration() const { return mCurrentGeneration; }
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inline bool IsMainThread() const { return mIsMainThread; }
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inline void SetObserverLists(uint32_t aNewGeneration,
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RefPtr<ObserverLists>& aNewLists) {
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mCurrentGeneration = aNewGeneration;
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mObserverLists = aNewLists;
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}
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inline void ClearObserverLists() {
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if (mObserverLists) {
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mCurrentGeneration = 0;
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mObserverLists = nullptr;
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}
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}
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private:
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bool mIsMainThread;
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bool mIsHandlingObservation;
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uint32_t mCurrentGeneration;
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RefPtr<ObserverLists> mObserverLists;
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};
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class MasterList {
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public:
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MasterList()
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: mObservedOperations(IOInterposeObserver::OpNone), mIsEnabled(true) {
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MOZ_COUNT_CTOR(MasterList);
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}
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~MasterList() { MOZ_COUNT_DTOR(MasterList); }
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inline void Disable() { mIsEnabled = false; }
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inline void Enable() { mIsEnabled = true; }
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void Register(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver) {
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IOInterposer::AutoLock lock(mLock);
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ObserverLists* newLists = nullptr;
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if (mObserverLists) {
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newLists = new ObserverLists(*mObserverLists);
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} else {
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newLists = new ObserverLists();
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}
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// You can register to observe multiple types of observations
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// but you'll never be registered twice for the same observations.
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if (aOp & IOInterposeObserver::OpCreateOrOpen &&
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!VectorContains(newLists->mCreateObservers, aObserver)) {
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newLists->mCreateObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpRead &&
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!VectorContains(newLists->mReadObservers, aObserver)) {
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newLists->mReadObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpWrite &&
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!VectorContains(newLists->mWriteObservers, aObserver)) {
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newLists->mWriteObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpFSync &&
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!VectorContains(newLists->mFSyncObservers, aObserver)) {
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newLists->mFSyncObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpStat &&
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!VectorContains(newLists->mStatObservers, aObserver)) {
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newLists->mStatObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpClose &&
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!VectorContains(newLists->mCloseObservers, aObserver)) {
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newLists->mCloseObservers.push_back(aObserver);
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}
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if (aOp & IOInterposeObserver::OpNextStage &&
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!VectorContains(newLists->mStageObservers, aObserver)) {
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newLists->mStageObservers.push_back(aObserver);
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}
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mObserverLists = newLists;
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mObservedOperations =
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(IOInterposeObserver::Operation)(mObservedOperations | aOp);
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mCurrentGeneration++;
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}
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void Unregister(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver) {
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IOInterposer::AutoLock lock(mLock);
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ObserverLists* newLists = nullptr;
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if (mObserverLists) {
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newLists = new ObserverLists(*mObserverLists);
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} else {
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newLists = new ObserverLists();
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}
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if (aOp & IOInterposeObserver::OpCreateOrOpen) {
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VectorRemove(newLists->mCreateObservers, aObserver);
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if (newLists->mCreateObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpCreateOrOpen);
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}
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}
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if (aOp & IOInterposeObserver::OpRead) {
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VectorRemove(newLists->mReadObservers, aObserver);
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if (newLists->mReadObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpRead);
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}
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}
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if (aOp & IOInterposeObserver::OpWrite) {
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VectorRemove(newLists->mWriteObservers, aObserver);
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if (newLists->mWriteObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpWrite);
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}
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}
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if (aOp & IOInterposeObserver::OpFSync) {
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VectorRemove(newLists->mFSyncObservers, aObserver);
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if (newLists->mFSyncObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpFSync);
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}
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}
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if (aOp & IOInterposeObserver::OpStat) {
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VectorRemove(newLists->mStatObservers, aObserver);
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if (newLists->mStatObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpStat);
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}
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}
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if (aOp & IOInterposeObserver::OpClose) {
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VectorRemove(newLists->mCloseObservers, aObserver);
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if (newLists->mCloseObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpClose);
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}
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}
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if (aOp & IOInterposeObserver::OpNextStage) {
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VectorRemove(newLists->mStageObservers, aObserver);
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if (newLists->mStageObservers.empty()) {
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mObservedOperations = (IOInterposeObserver::Operation)(
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mObservedOperations & ~IOInterposeObserver::OpNextStage);
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}
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}
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mObserverLists = newLists;
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mCurrentGeneration++;
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}
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void Update(PerThreadData& aPtd) {
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if (mCurrentGeneration == aPtd.GetCurrentGeneration()) {
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return;
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}
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// If the generation counts don't match then we need to update the current
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// thread's observer list with the new master list.
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IOInterposer::AutoLock lock(mLock);
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aPtd.SetObserverLists(mCurrentGeneration, mObserverLists);
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}
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inline bool IsObservedOperation(IOInterposeObserver::Operation aOp) {
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// The quick reader may observe that no locks are being employed here,
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// hence the result of the operations is truly undefined. However, most
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// computers will usually return either true or false, which is good enough.
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// It is not a problem if we occasionally report more or less IO than is
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// actually occurring.
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return mIsEnabled && !!(mObservedOperations & aOp);
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}
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private:
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RefPtr<ObserverLists> mObserverLists;
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// Note, we cannot use mozilla::Mutex here as the ObserverLists may be leaked
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// (We want to monitor IO during shutdown). Furthermore, as we may have to
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// unregister observers during shutdown an OffTheBooksMutex is not an option
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// either, as its base calls into sDeadlockDetector which may be nullptr
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// during shutdown.
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IOInterposer::Mutex mLock;
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// Flags tracking which operations are being observed
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IOInterposeObserver::Operation mObservedOperations;
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// Used for quickly disabling everything by IOInterposer::Disable()
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Atomic<bool> mIsEnabled;
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// Used to inform threads that the master observer list has changed
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Atomic<uint32_t> mCurrentGeneration;
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};
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// Special observation used by IOInterposer::EnteringNextStage()
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class NextStageObservation : public IOInterposeObserver::Observation {
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public:
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NextStageObservation()
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: IOInterposeObserver::Observation(IOInterposeObserver::OpNextStage,
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"IOInterposer", false) {
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mStart = TimeStamp::Now();
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mEnd = mStart;
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}
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};
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// List of observers registered
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static StaticAutoPtr<MasterList> sMasterList;
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static MOZ_THREAD_LOCAL(PerThreadData*) sThreadLocalData;
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static bool sThreadLocalDataInitialized;
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} // namespace
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IOInterposeObserver::Observation::Observation(Operation aOperation,
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const char* aReference,
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bool aShouldReport)
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: mOperation(aOperation),
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mReference(aReference),
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mShouldReport(IOInterposer::IsObservedOperation(aOperation) &&
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aShouldReport) {
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if (mShouldReport) {
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mStart = TimeStamp::Now();
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}
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}
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IOInterposeObserver::Observation::Observation(Operation aOperation,
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const TimeStamp& aStart,
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const TimeStamp& aEnd,
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const char* aReference)
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: mOperation(aOperation),
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mStart(aStart),
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mEnd(aEnd),
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mReference(aReference),
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mShouldReport(false) {}
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const char* IOInterposeObserver::Observation::ObservedOperationString() const {
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switch (mOperation) {
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case OpCreateOrOpen:
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return "create/open";
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case OpRead:
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return "read";
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case OpWrite:
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return "write";
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case OpFSync:
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return "fsync";
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case OpStat:
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return "stat";
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case OpClose:
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return "close";
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case OpNextStage:
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return "NextStage";
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default:
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return "unknown";
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}
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}
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void IOInterposeObserver::Observation::Report() {
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if (mShouldReport) {
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mEnd = TimeStamp::Now();
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IOInterposer::Report(*this);
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}
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}
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bool IOInterposer::Init() {
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// Don't initialize twice...
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if (sMasterList) {
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return true;
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}
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if (!sThreadLocalData.init()) {
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return false;
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}
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sThreadLocalDataInitialized = true;
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bool isMainThread = true;
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RegisterCurrentThread(isMainThread);
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sMasterList = new MasterList();
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MainThreadIOLogger::Init();
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// Now we initialize the various interposers depending on platform
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// Under certain conditions it may be unsafe to initialize PoisonIOInterposer,
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// such as when a background thread is already running. We set this variable
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// elsewhere when such a condition applies.
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if (!PR_GetEnv("MOZ_DISABLE_POISON_IO_INTERPOSER")) {
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InitPoisonIOInterposer();
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}
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// We don't hook NSPR on Windows because PoisonIOInterposer captures a
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// superset of the former's events.
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#if !defined(XP_WIN)
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InitNSPRIOInterposing();
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#endif
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return true;
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}
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bool IOInterposeObserver::IsMainThread() {
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if (!sThreadLocalDataInitialized) {
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return false;
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}
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PerThreadData* ptd = sThreadLocalData.get();
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if (!ptd) {
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return false;
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}
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return ptd->IsMainThread();
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}
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void IOInterposer::Clear() {
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/* Clear() is a no-op on release builds so that we may continue to trap I/O
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until process termination. In leak-checking builds, we need to shut down
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IOInterposer so that all references are properly released. */
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#ifdef NS_FREE_PERMANENT_DATA
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UnregisterCurrentThread();
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sMasterList = nullptr;
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#endif
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}
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void IOInterposer::Disable() {
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if (!sMasterList) {
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return;
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}
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sMasterList->Disable();
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}
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void IOInterposer::Enable() {
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if (!sMasterList) {
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return;
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}
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sMasterList->Enable();
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}
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void IOInterposer::Report(IOInterposeObserver::Observation& aObservation) {
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PerThreadData* ptd = sThreadLocalData.get();
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if (!ptd) {
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// In this case the current thread is not registered with IOInterposer.
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// Alternatively we could take the slow path and just lock everything if
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// we're not registered. That could potentially perform poorly, though.
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return;
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}
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if (!sMasterList) {
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// If there is no longer a master list then we should clear the local one.
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ptd->ClearObserverLists();
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return;
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}
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sMasterList->Update(*ptd);
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// Don't try to report if there's nobody listening.
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if (!IOInterposer::IsObservedOperation(aObservation.ObservedOperation())) {
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return;
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}
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ptd->CallObservers(aObservation);
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}
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bool IOInterposer::IsObservedOperation(IOInterposeObserver::Operation aOp) {
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return sMasterList && sMasterList->IsObservedOperation(aOp);
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}
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void IOInterposer::Register(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver) {
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MOZ_ASSERT(aObserver);
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if (!sMasterList || !aObserver) {
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return;
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}
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sMasterList->Register(aOp, aObserver);
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}
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void IOInterposer::Unregister(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver) {
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if (!sMasterList) {
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return;
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}
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sMasterList->Unregister(aOp, aObserver);
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}
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void IOInterposer::RegisterCurrentThread(bool aIsMainThread) {
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if (!sThreadLocalDataInitialized) {
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return;
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}
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MOZ_ASSERT(!sThreadLocalData.get());
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PerThreadData* curThreadData = new PerThreadData(aIsMainThread);
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sThreadLocalData.set(curThreadData);
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}
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void IOInterposer::UnregisterCurrentThread() {
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if (!sThreadLocalDataInitialized) {
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return;
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}
|
|
PerThreadData* curThreadData = sThreadLocalData.get();
|
|
MOZ_ASSERT(curThreadData);
|
|
sThreadLocalData.set(nullptr);
|
|
delete curThreadData;
|
|
}
|
|
|
|
void IOInterposer::EnteringNextStage() {
|
|
if (!sMasterList) {
|
|
return;
|
|
}
|
|
NextStageObservation observation;
|
|
Report(observation);
|
|
}
|