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/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. 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.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qplatformdefs.h"
#include "qplugin.h"
#include "qpluginloader.h"
#include <qfileinfo.h>
#include "qlibrary_p.h"
#include "qdebug.h"
#include "qdir.h"
#if defined(Q_OS_SYMBIAN)
# include <f32file.h>
# include "private/qcore_symbian_p.h"
#endif
#ifndef QT_NO_LIBRARY
QT_BEGIN_NAMESPACE
/*!
\class QPluginLoader
\reentrant
\brief The QPluginLoader class loads a plugin at run-time.
\ingroup plugins
QPluginLoader provides access to a \l{How to Create Qt
Plugins}{Qt plugin}. A Qt plugin is stored in a shared library (a
DLL) and offers these benefits over shared libraries accessed
using QLibrary:
\list
\o QPluginLoader checks that a plugin is linked against the same
version of Qt as the application.
\o QPluginLoader provides direct access to a root component object
(instance()), instead of forcing you to resolve a C function manually.
\endlist
An instance of a QPluginLoader object operates on a single shared
library file, which we call a plugin. It provides access to the
functionality in the plugin in a platform-independent way. To
specify which plugin to load, either pass a file name in
the constructor or set it with setFileName().
The most important functions are load() to dynamically load the
plugin file, isLoaded() to check whether loading was successful,
and instance() to access the root component in the plugin. The
instance() function implicitly tries to load the plugin if it has
not been loaded yet. Multiple instances of QPluginLoader can be
used to access the same physical plugin.
Once loaded, plugins remain in memory until all instances of
QPluginLoader has been unloaded, or until the application
terminates. You can attempt to unload a plugin using unload(),
but if other instances of QPluginLoader are using the same
library, the call will fail, and unloading will only happen when
every instance has called unload(). Right before the unloading
happen, the root component will also be deleted.
In order to speed up loading and validation of plugins, some of
the information that is collected during loading is cached in
persistent memory (through QSettings). For instance, the result
of a load operation (e.g. succeeded or failed) is stored in the
cache, so that subsequent load operations don't try to load an
invalid plugin. However, if the "last modified" timestamp of
a plugin has changed, the plugin's cache entry is invalidated
and the plugin is reloaded regardless of the values in the cache
entry. The cache entry is then updated with the new result of the
load operation.
This also means that the timestamp must be updated each time the
plugin or any dependent resources (such as a shared library) is
updated, since the dependent resources might influence the result
of loading a plugin.
See \l{How to Create Qt Plugins} for more information about
how to make your application extensible through plugins.
Note that the QPluginLoader cannot be used if your application is
statically linked against Qt. In this case, you will also have to
link to plugins statically. You can use QLibrary if you need to
load dynamic libraries in a statically linked application.
\note In Symbian the plugin stub files must be used whenever a
path to plugin is needed. For the purposes of loading plugins,
the stubs can be considered to have the same name as the actual
plugin binary. In practice they have ".qtplugin" extension
instead of ".dll", but this difference is handled transparently
by QPluginLoader and QLibrary to avoid need for Symbian specific
plugin handling in most Qt applications. Plugin stubs are needed
because Symbian Platform Security denies all access to the directory
where the actual plugin binaries are located.
\sa QLibrary, {Plug & Paint Example}
*/
/*!
Constructs a plugin loader with the given \a parent.
*/
QPluginLoader::QPluginLoader(QObject *parent)
: QObject(parent), d(0), did_load(false)
{
}
/*!
Constructs a plugin loader with the given \a parent that will
load the plugin specified by \a fileName.
To be loadable, the file's suffix must be a valid suffix for a
loadable library in accordance with the platform, e.g. \c .so on
Unix, - \c .dylib on Mac OS X, and \c .dll on Windows. The suffix
can be verified with QLibrary::isLibrary().
Note: In Symbian the \a fileName must point to plugin stub file.
\sa setFileName()
*/
QPluginLoader::QPluginLoader(const QString &fileName, QObject *parent)
: QObject(parent), d(0), did_load(false)
{
setFileName(fileName);
}
/*!
Destroys the QPluginLoader object.
Unless unload() was called explicitly, the plugin stays in memory
until the application terminates.
\sa isLoaded(), unload()
*/
QPluginLoader::~QPluginLoader()
{
if (d)
d->release();
}
/*!
Returns the root component object of the plugin. The plugin is
loaded if necessary. The function returns 0 if the plugin could
not be loaded or if the root component object could not be
instantiated.
If the root component object was destroyed, calling this function
creates a new instance.
The root component, returned by this function, is not deleted when
the QPluginLoader is destroyed. If you want to ensure that the root
component is deleted, you should call unload() as soon you don't
need to access the core component anymore. When the library is
finally unloaded, the root component will automatically be deleted.
The component object is a QObject. Use qobject_cast() to access
interfaces you are interested in.
\sa load()
*/
QObject *QPluginLoader::instance()
{
if (!load())
return 0;
if (!d->inst && d->instance)
d->inst = d->instance();
return d->inst.data();
}
/*!
Loads the plugin and returns true if the plugin was loaded
successfully; otherwise returns false. Since instance() always
calls this function before resolving any symbols it is not
necessary to call it explicitly. In some situations you might want
the plugin loaded in advance, in which case you would use this
function.
\sa unload()
*/
bool QPluginLoader::load()
{
if (!d || d->fileName.isEmpty())
return false;
if (did_load)
return d->pHnd && d->instance;
if (!d->isPlugin())
return false;
did_load = true;
return d->loadPlugin();
}
/*!
Unloads the plugin and returns true if the plugin could be
unloaded; otherwise returns false.
This happens automatically on application termination, so you
shouldn't normally need to call this function.
If other instances of QPluginLoader are using the same plugin, the
call will fail, and unloading will only happen when every instance
has called unload().
Don't try to delete the root component. Instead rely on
that unload() will automatically delete it when needed.
\sa instance(), load()
*/
bool QPluginLoader::unload()
{
if (did_load) {
did_load = false;
return d->unload();
}
if (d) // Ouch
d->errorString = tr("The plugin was not loaded.");
return false;
}
/*!
Returns true if the plugin is loaded; otherwise returns false.
\sa load()
*/
bool QPluginLoader::isLoaded() const
{
return d && d->pHnd && d->instance;
}
/*!
\property QPluginLoader::fileName
\brief the file name of the plugin
To be loadable, the file's suffix must be a valid suffix for a
loadable library in accordance with the platform, e.g. \c .so on
Unix, \c .dylib on Mac OS X, and \c .dll on Windows. The suffix
can be verified with QLibrary::isLibrary().
If the file name does not exist, it will not be set. This property
will then contain an empty string.
By default, this property contains an empty string.
Note: In Symbian the \a fileName must point to plugin stub file.
\sa load()
*/
void QPluginLoader::setFileName(const QString &fileName)
{
#if defined(QT_SHARED)
QLibrary::LoadHints lh;
if (d) {
lh = d->loadHints;
d->release();
d = 0;
did_load = false;
}
#if defined(Q_OS_SYMBIAN)
// In Symbian we actually look for plugin stub, so modify the filename
// to make canonicalFilePath find the file, if .dll is specified.
QFileInfo fi(fileName);
if (fi.suffix() == QLatin1String("dll")) {
QString stubName = fileName;
stubName.chop(3);
stubName += QLatin1String("qtplugin");
fi = QFileInfo(stubName);
}
QString fn = fi.canonicalFilePath();
// If not found directly, check also all the available drives
if (!fn.length()) {
QString stubPath(fi.fileName().length() ? fi.absoluteFilePath() : QString());
if (stubPath.length() > 1) {
if (stubPath.at(1).toAscii() == ':')
stubPath.remove(0,2);
QFileInfoList driveList(QDir::drives());
RFs rfs = qt_s60GetRFs();
foreach(const QFileInfo& drive, driveList) {
QString testFilePath(drive.absolutePath() + stubPath);
testFilePath = QDir::cleanPath(testFilePath);
// Use native Symbian code to check for file existence, because checking
// for file from under non-existent protected dir like E:/private/<uid> using
// QFile::exists causes platform security violations on most apps.
QString nativePath = QDir::toNativeSeparators(testFilePath);
TPtrC ptr(qt_QString2TPtrC(nativePath));
TUint attributes;
TInt err = rfs.Att(ptr, attributes);
if (err == KErrNone) {
fn = testFilePath;
break;
}
}
}
}
#else
QString fn = QFileInfo(fileName).canonicalFilePath();
#endif
d = QLibraryPrivate::findOrCreate(fn);
d->loadHints = lh;
if (fn.isEmpty())
d->errorString = QLibrary::tr("The shared library was not found.");
#else
if (qt_debug_component()) {
qWarning("Cannot load %s into a statically linked Qt library.",
(const char*)QFile::encodeName(fileName));
}
Q_UNUSED(fileName);
#endif
}
QString QPluginLoader::fileName() const
{
if (d)
return d->fileName;
return QString();
}
/*!
\since 4.2
Returns a text string with the description of the last error that occurred.
*/
QString QPluginLoader::errorString() const
{
return (!d || d->errorString.isEmpty()) ? tr("Unknown error") : d->errorString;
}
typedef QList<QtPluginInstanceFunction> StaticInstanceFunctionList;
Q_GLOBAL_STATIC(StaticInstanceFunctionList, staticInstanceFunctionList)
/*! \since 4.4
\property QPluginLoader::loadHints
\brief Give the load() function some hints on how it should behave.
You can give hints on how the symbols in the plugin are
resolved. By default, none of the hints are set.
See the documentation of QLibrary::loadHints for a complete
description of how this property works.
\sa QLibrary::loadHints
*/
void QPluginLoader::setLoadHints(QLibrary::LoadHints loadHints)
{
if (!d) {
d = QLibraryPrivate::findOrCreate(QString()); // ugly, but we need a d-ptr
d->errorString.clear();
}
d->loadHints = loadHints;
}
QLibrary::LoadHints QPluginLoader::loadHints() const
{
if (!d) {
QPluginLoader *that = const_cast<QPluginLoader *>(this);
that->d = QLibraryPrivate::findOrCreate(QString()); // ugly, but we need a d-ptr
that->d->errorString.clear();
}
return d->loadHints;
}
/*!
\relates QPluginLoader
\since 4.4
Registers the given \a function with the plugin loader.
*/
void Q_CORE_EXPORT qRegisterStaticPluginInstanceFunction(QtPluginInstanceFunction function)
{
staticInstanceFunctionList()->append(function);
}
/*!
Returns a list of static plugin instances (root components) held
by the plugin loader.
*/
QObjectList QPluginLoader::staticInstances()
{
QObjectList instances;
StaticInstanceFunctionList *functions = staticInstanceFunctionList();
if (functions) {
for (int i = 0; i < functions->count(); ++i)
instances.append((*functions)[i]());
}
return instances;
}
QT_END_NAMESPACE
#endif // QT_NO_LIBRARY
|