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Please review the following information to ** ensure the GNU General Public License version 3.0 requirements will be ** met: http://www.gnu.org/copyleft/gpl.html. ** ** If you are unsure which license is appropriate for your use, please ** contact the sales department at http://www.qtsoftware.com/contact. ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qsharedpointer.h" // to be sure we aren't causing a namespace clash: #include "qshareddata.h" /*! \class QSharedPointer \brief The QSharedPointer class holds a strong reference to a shared pointer \since 4.5 \reentrant \ingroup misc The QSharedPointer is an automatic, shared pointer in C++. It behaves exactly like a normal pointer for normal purposes, including respect for constness. QSharedPointer will delete the pointer it is holding when it goes out of scope, provided no other QSharedPointer objects are referencing it. A QSharedPointer object can be created from a normal pointer, another QSharedPointer object or by promoting a QWeakPointer object to a strong reference. \section1 Thread-Safety QSharedPointer and QWeakPointer are thread-safe and operate atomically on the pointer value. Different threads can also access the same QSharedPointer or QWeakPointer object at the same time without need for locking mechanisms. It should be noted that, while the pointer value can be accessed in this manner, QSharedPointer and QWeakPointer provide no guarantee about the object being pointed to. Thread-safety and reentrancy rules for that object still apply. \section1 Other Pointer Classes Qt also provides two other pointer wrapper classes: QPointer and QSharedDataPointer. They are incompatible with one another, since each has its very different use case. QSharedPointer holds a shared pointer by means of an external reference count (i.e., a reference counter placed outside the object). Like its name indicates, the pointer value is shared among all instances of QSharedPointer and QWeakPointer. The contents of the object pointed to by the pointer should not considered shared, however: there is only one object. For that reason, QSharedPointer does not provide a way to detach or make copies of the pointed object. QSharedDataPointer, on the other hand, holds a pointer to shared data (i.e., a class derived from QSharedData). It does so by means of an internal reference count, placed in the QSharedData base class. This class can, therefore, detach based on the type of access made to the data being guarded: if it's a non-const access, it creates a copy atomically for the operation to complete. QExplicitlySharedDataPointer behaves like QSharedDataPointer, except that it only detaches if QExplicitlySharedDataPointer::detach() is explicitly called. Finally, QPointer holds a pointer to a QObject-derived object, but it does so weakly. QPointer is similar, in that behaviour, to QWeakPointer: it does not allow you to prevent the object from being destroyed. All you can do is query whether it has been destroyed or not. \sa QSharedDataPointer, QWeakPointer */ /*! \class QWeakPointer \brief The QWeakPointer class holds a weak reference to a shared pointer \since 4.5 \reentrant \ingroup misc The QWeakPointer is an automatic weak reference to a pointer in C++. It cannot be used to dereference the pointer directly, but it can be used to verify if the pointer has been deleted or not in another context. QWeakPointer objects can only be created by assignment from a QSharedPointer. To access the pointer that QWeakPointer is tracking, you must first create a QSharedPointer object and verify if the pointer is null or not. See QWeakPointer::toStrongRef() for more information. \sa QSharedPointer */ /*! \fn QSharedPointer::QSharedPointer() Creates a QSharedPointer that points to null (0). */ /*! \fn QSharedPointer::~QSharedPointer() Destroys this QSharedPointer object. If it is the last reference to the pointer stored, this will delete the pointer as well. */ /*! \fn QSharedPointer::QSharedPointer(T *ptr) Creates a QSharedPointer that points to \a ptr. The pointer \a ptr becomes managed by this QSharedPointer and must not be passed to another QSharedPointer object or deleted outside this object. */ /*! \fn QSharedPointer::QSharedPointer(T *ptr, Deleter deleter) Creates a QSharedPointer that points to \a ptr. The pointer \a ptr becomes managed by this QSharedPointer and must not be passed to another QSharedPointer object or deleted outside this object. The \a deleter paramter specifies the custom deleter for this object. The custom deleter is called when the strong reference count drops to 0 instead of the operator delete(). This is useful, for instance, for calling deleteLater() in a QObject instead: \code static void doDeleteLater(MyObject *obj) { obj->deleteLater(); } void otherFunction() { QSharedPointer obj = QSharedPointer(new MyObject, doDeleteLater); // continue using obj obj.clear(); // calls obj->deleteLater(); } \endcode It is also possible to specify a member function directly, as in: \code QSharedPointer obj = QSharedPointer(new MyObject, &QObject::deleteLater); \endcode \sa clear() */ /*! \fn QSharedPointer::QSharedPointer(const QSharedPointer &other) Creates a QSharedPointer object that shares \a other's pointer. If \tt T is a derived type of the template parameter of this class, QSharedPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn QSharedPointer::QSharedPointer(const QWeakPointer &other) Creates a QSharedPointer by promoting the weak reference \a other to strong reference and sharing its pointer. If \tt T is a derived type of the template parameter of this class, QSharedPointer will perform an automatic cast. Otherwise, you will get a compiler error. \sa QWeakPointer::toStrongRef() */ /*! \fn QSharedPointer &QSharedPointer::operator=(const QSharedPointer &other) Makes this object share \a other's pointer. The current pointer reference is discarded and, if it was the last, the pointer will be deleted. If \tt T is a derived type of the template parameter of this class, QSharedPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn QSharedPointer &QSharedPointer::operator=(const QWeakPointer &other) Promotes \a other to a strong reference and makes this object share a reference to the pointer referenced by it. The current pointer reference is discarded and, if it was the last, the pointer will be deleted. If \tt T is a derived type of the template parameter of this class, QSharedPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn T *QSharedPointer::data() const Returns the value of the pointer referenced by this object. Note: do not delete the pointer returned by this function or pass it to another function that could delete it, including creating QSharedPointer or QWeakPointer objects. */ /*! \fn T &QSharedPointer::operator *() const Provides access to the shared pointer's members. \sa isNull() */ /*! \fn T *QSharedPointer::operator ->() const Provides access to the shared pointer's members. \sa isNull() */ /*! \fn bool QSharedPointer::isNull() const Returns true if this object is holding a reference to a null pointer. */ /*! \fn QSharedPointer::operator bool() const Returns true if this object is not null. This function is suitable for use in \tt if-constructs, like: \code if (sharedptr) { ... } \endcode \sa isNull() */ /*! \fn bool QSharedPointer::operator !() const Returns true if this object is null. This function is suitable for use in \tt if-constructs, like: \code if (!sharedptr) { ... } \endcode \sa isNull() */ /*! \fn QSharedPointer QSharedPointer::staticCast() const Performs a static cast from this pointer's type to \tt X and returns a QSharedPointer that shares the reference. This function can be used for up- and for down-casting, but is more useful for up-casting. Note: the template type \c X must have the same const and volatile qualifiers as the template of this object, or the cast will fail. Use constCast() if you need to drop those qualifiers. \sa dynamicCast(), constCast(), qSharedPointerCast() */ /*! \fn QSharedPointer QSharedPointer::dynamicCast() const Performs a dynamic cast from this pointer's type to \tt X and returns a QSharedPointer that shares the reference. If this function is used to up-cast, then QSharedPointer will perform a \tt dynamic_cast, which means that if the object being pointed by this QSharedPointer is not of type \tt X, the returned object will be null. Note: the template type \c X must have the same const and volatile qualifiers as the template of this object, or the cast will fail. Use constCast() if you need to drop those qualifiers. \sa qSharedPointerDynamicCast() */ /*! \fn QSharedPointer QSharedPointer::constCast() const Performs a \tt const_cast from this pointer's type to \tt X and returns a QSharedPointer that shares the reference. This function can be used for up- and for down-casting, but is more useful for up-casting. \sa isNull(), qSharedPointerConstCast() */ /*! \fn QSharedPointer QSharedPointer::objectCast() const \since 4.6 Performs a \l qobject_cast() from this pointer's type to \tt X and returns a QSharedPointer that shares the reference. If this function is used to up-cast, then QSharedPointer will perform a \tt qobject_cast, which means that if the object being pointed by this QSharedPointer is not of type \tt X, the returned object will be null. Note: the template type \c X must have the same const and volatile qualifiers as the template of this object, or the cast will fail. Use constCast() if you need to drop those qualifiers. \sa qSharedPointerObjectCast() */ /*! \fn QWeakPointer QSharedPointer::toWeakRef() const Returns a weak reference object that shares the pointer referenced by this object. \sa QWeakPointer::QWeakPointer() */ /*! \fn void QSharedPointer::clear() Clears this QSharedPointer object, dropping the reference that it may have had to the pointer. If this was the last reference, then the pointer itself will be deleted. */ /*! \fn QWeakPointer::QWeakPointer() Creates a QWeakPointer that points to nothing. */ /*! \fn QWeakPointer::~QWeakPointer() Destroys this QWeakPointer object. The pointer referenced by this object will not be deleted. */ /*! \fn QWeakPointer::QWeakPointer(const QWeakPointer &other) Creates a QWeakPointer that holds a weak reference to the pointer referenced by \a other. If \tt T is a derived type of the template parameter of this class, QWeakPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn QWeakPointer::QWeakPointer(const QSharedPointer &other) Creates a QWeakPointer that holds a weak reference to the pointer referenced by \a other. If \tt T is a derived type of the template parameter of this class, QWeakPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn QWeakPointer &QWeakPointer::operator=(const QWeakPointer &other) Makes this object share \a other's pointer. The current pointer reference is discarded but is not deleted. If \tt T is a derived type of the template parameter of this class, QWeakPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn QWeakPointer &QWeakPointer::operator=(const QSharedPointer &other) Makes this object share \a other's pointer. The current pointer reference is discarded but is not deleted. If \tt T is a derived type of the template parameter of this class, QWeakPointer will perform an automatic cast. Otherwise, you will get a compiler error. */ /*! \fn bool QWeakPointer::isNull() const Returns true if this object is holding a reference to a null pointer. Note that, due to the nature of weak references, the pointer that QWeakPointer references can become null at any moment, so the value returned from this function can change from false to true from one call to the next. */ /*! \fn QWeakPointer::operator bool() const Returns true if this object is not null. This function is suitable for use in \tt if-constructs, like: \code if (weakref) { ... } \endcode Note that, due to the nature of weak references, the pointer that QWeakPointer references can become null at any moment, so the value returned from this function can change from true to false from one call to the next. \sa isNull() */ /*! \fn bool QWeakPointer::operator !() const Returns true if this object is null. This function is suitable for use in \tt if-constructs, like: \code if (!weakref) { ... } \endcode Note that, due to the nature of weak references, the pointer that QWeakPointer references can become null at any moment, so the value returned from this function can change from false to true from one call to the next. \sa isNull() */ /*! \fn T *QWeakPointer::data() const \since 4.6 Returns the value of the pointer being tracked by this QWeakPointer, \b without ensuring that it cannot get deleted. To have that guarantee, use toStrongRef(), which returns a QSharedPointer object. If this function can determine that the pointer has already been deleted, it returns 0. It is ok to obtain the value of the pointer and using that value itself, like for example in debugging statements: \code qDebug("Tracking %p", weakref.data()); \endcode However, dereferencing the pointer is only allowed if you can guarantee by external means that the pointer does not get deleted. For example, if you can be certain that no other thread can delete it, nor the functions that you may call. If that is the case, then the following code is valid: \code // this pointer cannot be used in another thread // so other threads cannot delete it QWeakPointer weakref = obtainReference(); Object *obj = weakref.data(); if (obj) { // if the pointer wasn't deleted yet, we know it can't get // deleted by our own code here nor the functions we call otherFunction(obj); } \endcode Use this function with care. \sa isNull(), toStrongRef() */ /*! \fn QSharedPointer QWeakPointer::toStrongRef() const Promotes this weak reference to a strong one and returns a QSharedPointer object holding that reference. When promoting to QSharedPointer, this function verifies if the object has been deleted already or not. If it hasn't, this function increases the reference count to the shared object, thus ensuring that it will not get deleted. Since this function can fail to obtain a valid strong reference to the shared object, you should always verify if the conversion succeeded, by calling QSharedPointer::isNull() on the returned object. For example, the following code promotes a QWeakPointer that was held to a strong reference and, if it succeeded, it prints the value of the integer that was held: \code QWeakPointer weakref; // ... QSharedPointer strong = weakref.toStrongRef(); if (strong) qDebug() << "The value is:" << *strong; else qDebug() << "The value has already been deleted"; \endcode \sa QSharedPointer::QSharedPointer() */ /*! \fn void QWeakPointer::clear() Clears this QWeakPointer object, dropping the reference that it may have had to the pointer. */ /*! \fn bool operator==(const QSharedPointer &ptr1, const QSharedPointer &ptr2) \relates QSharedPointer Returns true if the pointer referenced by \a ptr1 is the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn bool operator!=(const QSharedPointer &ptr1, const QSharedPointer &ptr2) \relates QSharedPointer Returns true if the pointer referenced by \a ptr1 is not the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn bool operator==(const QSharedPointer &ptr1, const X *ptr2) \relates QSharedPointer Returns true if the pointer referenced by \a ptr1 is the same pointer as \a ptr2. If \a ptr2's type is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's type is not a base or a derived type from this \a ptr1's, you will get a compiler error. */ /*! \fn bool operator!=(const QSharedPointer &ptr1, const X *ptr2) \relates QSharedPointer Returns true if the pointer referenced by \a ptr1 is not the same pointer as \a ptr2. If \a ptr2's type is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's type is not a base or a derived type from this \a ptr1's, you will get a compiler error. */ /*! \fn bool operator==(const T *ptr1, const QSharedPointer &ptr2) \relates QSharedPointer Returns true if the pointer \a ptr1 is the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's type, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's type, you will get a compiler error. */ /*! \fn bool operator!=(const T *ptr1, const QSharedPointer &ptr2) \relates QSharedPointer Returns true if the pointer \a ptr1 is not the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's type, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's type, you will get a compiler error. */ /*! \fn bool operator==(const QSharedPointer &ptr1, const QWeakPointer &ptr2) \relates QWeakPointer Returns true if the pointer referenced by \a ptr1 is the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn bool operator!=(const QSharedPointer &ptr1, const QWeakPointer &ptr2) \relates QWeakPointer Returns true if the pointer referenced by \a ptr1 is not the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn bool operator==(const QWeakPointer &ptr1, const QSharedPointer &ptr2) \relates QWeakPointer Returns true if the pointer referenced by \a ptr1 is the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn bool operator!=(const QWeakPointer &ptr1, const QSharedPointer &ptr2) \relates QWeakPointer Returns true if the pointer referenced by \a ptr1 is not the same pointer as that referenced by \a ptr2. If \a ptr2's template parameter is different from \a ptr1's, QSharedPointer will attempt to perform an automatic \tt static_cast to ensure that the pointers being compared are equal. If \a ptr2's template parameter is not a base or a derived type from \a ptr1's, you will get a compiler error. */ /*! \fn QSharedPointer qSharedPointerCast(const QSharedPointer &other) \relates QSharedPointer Returns a shared pointer to the pointer held by \a other, cast to type \tt X. The types \tt T and \tt X must belong to one hierarchy for the \tt static_cast to succeed. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QSharedPointer::staticCast(), qSharedPointerDynamicCast(), qSharedPointerConstCast() */ /*! \fn QSharedPointer qSharedPointerCast(const QWeakPointer &other) \relates QSharedPointer \relates QWeakPointer Returns a shared pointer to the pointer held by \a other, cast to type \tt X. The types \tt T and \tt X must belong to one hierarchy for the \tt static_cast to succeed. The \a other object is converted first to a strong reference. If that conversion fails (because the object it's pointing to has already been deleted), this function returns a null QSharedPointer. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QWeakPointer::toStrongRef(), qSharedPointerDynamicCast(), qSharedPointerConstCast() */ /*! \fn QSharedPointer qSharedPointerDynamicCast(const QSharedPointer &other) \relates QSharedPointer Returns a shared pointer to the pointer held by \a other, using a dynamic cast to type \tt X to obtain an internal pointer of the appropriate type. If the \tt dynamic_cast fails, the object returned will be null. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QSharedPointer::dynamicCast(), qSharedPointerCast(), qSharedPointerConstCast() */ /*! \fn QSharedPointer qSharedPointerDynamicCast(const QWeakPointer &other) \relates QSharedPointer \relates QWeakPointer Returns a shared pointer to the pointer held by \a other, using a dynamic cast to type \tt X to obtain an internal pointer of the appropriate type. If the \tt dynamic_cast fails, the object returned will be null. The \a other object is converted first to a strong reference. If that conversion fails (because the object it's pointing to has already been deleted), this function also returns a null QSharedPointer. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QWeakPointer::toStrongRef(), qSharedPointerCast(), qSharedPointerConstCast() */ /*! \fn QSharedPointer qSharedPointerConstCast(const QSharedPointer &other) \relates QSharedPointer Returns a shared pointer to the pointer held by \a other, cast to type \tt X. The types \tt T and \tt X must belong to one hierarchy for the \tt const_cast to succeed. The \tt const and \tt volatile differences between \tt T and \tt X are ignored. \sa QSharedPointer::constCast(), qSharedPointerCast(), qSharedPointerDynamicCast() */ /*! \fn QSharedPointer qSharedPointerConstCast(const QWeakPointer &other) \relates QSharedPointer \relates QWeakPointer Returns a shared pointer to the pointer held by \a other, cast to type \tt X. The types \tt T and \tt X must belong to one hierarchy for the \tt const_cast to succeed. The \tt const and \tt volatile differences between \tt T and \tt X are ignored. The \a other object is converted first to a strong reference. If that conversion fails (because the object it's pointing to has already been deleted), this function returns a null QSharedPointer. \sa QWeakPointer::toStrongRef(), qSharedPointerCast(), qSharedPointerDynamicCast() */ /*! \fn QSharedPointer qSharedPointerObjectCast(const QSharedPointer &other) \relates QSharedPointer \since 4.6 Returns a shared pointer to the pointer held by \a other, using a \l qobject_cast() to type \tt X to obtain an internal pointer of the appropriate type. If the \tt qobject_cast fails, the object returned will be null. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QSharedPointer::objectCast(), qSharedPointerCast(), qSharedPointerConstCast() */ /*! \fn QSharedPointer qSharedPointerObjectCast(const QWeakPointer &other) \relates QSharedPointer \relates QWeakPointer \since 4.6 Returns a shared pointer to the pointer held by \a other, using a \l qobject_cast() to type \tt X to obtain an internal pointer of the appropriate type. If the \tt qobject_cast fails, the object returned will be null. The \a other object is converted first to a strong reference. If that conversion fails (because the object it's pointing to has already been deleted), this function also returns a null QSharedPointer. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. \sa QWeakPointer::toStrongRef(), qSharedPointerCast(), qSharedPointerConstCast() */ /*! \fn QWeakPointer qWeakPointerCast(const QWeakPointer &other) \relates QWeakPointer Returns a weak pointer to the pointer held by \a other, cast to type \tt X. The types \tt T and \tt X must belong to one hierarchy for the \tt static_cast to succeed. Note that \tt X must have the same cv-qualifiers (\tt const and \tt volatile) that \tt T has, or the code will fail to compile. Use qSharedPointerConstCast to cast away the constness. */ #include #include #if !defined(QT_NO_QOBJECT) #include "../kernel/qobject_p.h" QT_BEGIN_NAMESPACE /*! \internal This function is called for a just-created QObject \a obj, to enable the use of QSharedPointer and QWeakPointer. When QSharedPointer is active in a QObject, the object must not be deleted directly: the lifetime is managed by the QSharedPointer object. In that case, the deleteLater() and parent-child relationship in QObject only decrease the strong reference count, instead of deleting the object. */ void QtSharedPointer::ExternalRefCountData::setQObjectShared(const QObject *obj, bool) { Q_ASSERT(obj); QObjectPrivate *d = QObjectPrivate::get(const_cast(obj)); if (d->sharedRefcount) qFatal("QSharedPointer: pointer %p already has reference counting", obj); d->sharedRefcount = this; // QObject decreases the refcount too, so increase it up weakref.ref(); } QtSharedPointer::ExternalRefCountData *QtSharedPointer::ExternalRefCountData::getAndRef(const QObject *obj) { Q_ASSERT(obj); QObjectPrivate *d = QObjectPrivate::get(const_cast(obj)); ExternalRefCountData *that = d->sharedRefcount; if (that) { that->weakref.ref(); return that; } // we can create the refcount data because it doesn't exist ExternalRefCountData *x = new ExternalRefCountData(Qt::Uninitialized); x->strongref = -1; x->weakref = 2; // the QWeakPointer that called us plus the QObject itself if (!d->sharedRefcount.testAndSetRelease(0, x)) { delete x; d->sharedRefcount->weakref.ref(); } return d->sharedRefcount; } QT_END_NAMESPACE #endif #if !defined(QT_NO_MEMBER_TEMPLATES) //# define QT_SHARED_POINTER_BACKTRACE_SUPPORT # ifdef QT_SHARED_POINTER_BACKTRACE_SUPPORT # if defined(__GLIBC__) && (__GLIBC__ >= 2) && !defined(__UCLIBC__) && !defined(QT_LINUXBASE) # define BACKTRACE_SUPPORTED # elif defined(Q_OS_MACX) # define BACKTRACE_SUPPORTED # endif # endif # if defined(BACKTRACE_SUPPORTED) # include # include # include # include # include QT_BEGIN_NAMESPACE static inline QByteArray saveBacktrace() __attribute__((always_inline)); static inline QByteArray saveBacktrace() { static const int maxFrames = 32; QByteArray stacktrace; stacktrace.resize(sizeof(void*) * maxFrames); int stack_size = backtrace((void**)stacktrace.data(), maxFrames); stacktrace.resize(sizeof(void*) * stack_size); return stacktrace; } static void printBacktrace(QByteArray stacktrace) { void *const *stack = (void *const *)stacktrace.constData(); int stack_size = stacktrace.size() / sizeof(void*); char **stack_symbols = backtrace_symbols(stack, stack_size); int filter[2]; pid_t child = -1; if (pipe(filter) != -1) child = fork(); if (child == 0) { // child process dup2(fileno(stderr), fileno(stdout)); dup2(filter[0], fileno(stdin)); close(filter[0]); close(filter[1]); execlp("c++filt", "c++filt", "-n", NULL); // execlp failed execl("/bin/cat", "/bin/cat", NULL); _exit(127); } // parent process close(filter[0]); FILE *output; if (child == -1) { // failed forking close(filter[1]); output = stderr; } else { output = fdopen(filter[1], "w"); } fprintf(stderr, "Backtrace of the first creation (most recent frame first):\n"); for (int i = 0; i < stack_size; ++i) { if (strlen(stack_symbols[i])) fprintf(output, "#%-2d %s\n", i, stack_symbols[i]); else fprintf(output, "#%-2d %p\n", i, stack[i]); } if (child != -1) { fclose(output); waitpid(child, 0, 0); } } QT_END_NAMESPACE # endif // BACKTRACE_SUPPORTED namespace { QT_USE_NAMESPACE struct Data { const volatile void *pointer; # ifdef BACKTRACE_SUPPORTED QByteArray backtrace; # endif }; class KnownPointers { public: QMutex mutex; QHash dPointers; QHash dataPointers; }; } Q_GLOBAL_STATIC(KnownPointers, knownPointers) QT_BEGIN_NAMESPACE namespace QtSharedPointer { Q_CORE_EXPORT void internalSafetyCheckAdd(const volatile void *); Q_CORE_EXPORT void internalSafetyCheckRemove(const volatile void *); Q_AUTOTEST_EXPORT void internalSafetyCheckCleanCheck(); } /*! \internal */ void QtSharedPointer::internalSafetyCheckAdd(const volatile void *) { // Qt 4.5 compatibility // this function is broken by design, so it was replaced with internalSafetyCheckAdd2 // // it's broken because we tracked the pointers added and // removed from QSharedPointer, converted to void*. // That is, this is supposed to track the "top-of-object" pointer in // case of multiple inheritance. // // However, it doesn't work well in some compilers: // if you create an object with a class of type A and the last reference // is dropped of type B, then the value passed to internalSafetyCheckRemove could // be different than was added. That would leave dangling addresses. // // So instead, we track the pointer by the d-pointer instead. } /*! \internal */ void QtSharedPointer::internalSafetyCheckRemove(const volatile void *) { // Qt 4.5 compatibility // see comments above } /*! \internal */ void QtSharedPointer::internalSafetyCheckAdd2(const void *d_ptr, const volatile void *ptr) { // see comments above for the rationale for this function KnownPointers *const kp = knownPointers(); if (!kp) return; // end-game: the application is being destroyed already QMutexLocker lock(&kp->mutex); Q_ASSERT(!kp->dPointers.contains(d_ptr)); //qDebug("Adding d=%p value=%p", d_ptr, ptr); const void *other_d_ptr = kp->dataPointers.value(ptr, 0); if (other_d_ptr) { # ifdef BACKTRACE_SUPPORTED printBacktrace(knownPointers()->dPointers.value(other_d_ptr).backtrace); # endif qFatal("QSharedPointer: internal self-check failed: pointer %p was already tracked " "by another QSharedPointer object %p", ptr, other_d_ptr); } Data data; data.pointer = ptr; # ifdef BACKTRACE_SUPPORTED data.backtrace = saveBacktrace(); # endif kp->dPointers.insert(d_ptr, data); kp->dataPointers.insert(ptr, d_ptr); Q_ASSERT(kp->dPointers.size() == kp->dataPointers.size()); } /*! \internal */ void QtSharedPointer::internalSafetyCheckRemove2(const void *d_ptr) { KnownPointers *const kp = knownPointers(); if (!kp) return; // end-game: the application is being destroyed already QMutexLocker lock(&kp->mutex); QHash::iterator it = kp->dPointers.find(d_ptr); if (it == kp->dPointers.end()) { qFatal("QSharedPointer: internal self-check inconsistency: pointer %p was not tracked. " "To use QT_SHAREDPOINTER_TRACK_POINTERS, you have to enable it throughout " "in your code.", d_ptr); } QHash::iterator it2 = kp->dataPointers.find(it->pointer); Q_ASSERT(it2 != kp->dataPointers.end()); //qDebug("Removing d=%p value=%p", d_ptr, it->pointer); // remove entries kp->dataPointers.erase(it2); kp->dPointers.erase(it); Q_ASSERT(kp->dPointers.size() == kp->dataPointers.size()); } /*! \internal Called by the QSharedPointer autotest */ void QtSharedPointer::internalSafetyCheckCleanCheck() { # ifdef QT_BUILD_INTERNAL KnownPointers *const kp = knownPointers(); Q_ASSERT_X(kp, "internalSafetyCheckSelfCheck()", "Called after global statics deletion!"); if (kp->dPointers.size() != kp->dataPointers.size()) qFatal("Internal consistency error: the number of pointers is not equal!"); if (!kp->dPointers.isEmpty()) qFatal("Pointer cleaning failed: %d entries remaining", kp->dPointers.size()); # endif } QT_END_NAMESPACE #endif