/**************************************************************************** ** $Id$ ** ** Implementation of QLibrary class ** ** Created : 2000-01-01 ** ** Copyright (C) 2000-2002 Trolltech AS. All rights reserved. ** ** This file is part of the tools module of the Qt GUI Toolkit. ** ** This file may be distributed under the terms of the Q Public License ** as defined by Trolltech AS of Norway and appearing in the file ** LICENSE.QPL included in the packaging of this file. ** ** This file may be distributed and/or modified under the terms of the ** GNU General Public License version 2 as published by the Free Software ** Foundation and appearing in the file LICENSE.GPL included in the ** packaging of this file. ** ** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition ** licenses may use this file in accordance with the Qt Commercial License ** Agreement provided with the Software. ** ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ** ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for ** information about Qt Commercial License Agreements. ** See http://www.trolltech.com/qpl/ for QPL licensing information. ** See http://www.trolltech.com/gpl/ for GPL licensing information. ** ** Contact info@trolltech.com if any conditions of this licensing are ** not clear to you. ** **********************************************************************/ #include "qplatformdefs.h" #include <private/qlibrary_p.h> #ifndef QT_NO_LIBRARY // uncomment this to get error messages //#define QT_DEBUG_COMPONENT 1 // uncomment this to get error and success messages //#define QT_DEBUG_COMPONENT 2 #ifndef QT_DEBUG_COMPONENT # if defined(QT_DEBUG) # define QT_DEBUG_COMPONENT 1 # endif #endif #if defined(QT_DEBUG_COMPONENT) #include <qfile.h> #endif #if defined(Q_WS_WIN) && !defined(QT_MAKEDLL) #define QT_NO_LIBRARY_UNLOAD #endif QLibraryPrivate::QLibraryPrivate( QLibrary *lib ) : pHnd( 0 ), library( lib ) { } /*! \class QLibrary qlibrary.h \reentrant \brief The QLibrary class provides a wrapper for handling shared libraries. \mainclass \group plugins An instance of a QLibrary object can handle a single shared library and provide access to the functionality in the library in a platform independent way. If the library is a component server, QLibrary provides access to the exported component and can directly query this component for interfaces. QLibrary ensures that the shared library is loaded and stays in memory whilst it is in use. QLibrary can also unload the library on destruction and release unused resources. A typical use of QLibrary is to resolve an exported symbol in a shared object, and to call the function that this symbol represents. This is called "explicit linking" in contrast to "implicit linking", which is done by the link step in the build process when linking an executable against a library. The following code snippet loads a library, resolves the symbol "mysymbol", and calls the function if everything succeeded. If something went wrong, e.g. the library file does not exist or the symbol is not defined, the function pointer will be 0 and won't be called. When the QLibrary object is destroyed the library will be unloaded, making all references to memory allocated in the library invalid. \code typedef void (*MyPrototype)(); MyPrototype myFunction; QLibrary myLib( "mylib" ); myFunction = (MyProtoype) myLib.resolve( "mysymbol" ); if ( myFunction ) { myFunction(); } \endcode */ /*! Creates a QLibrary object for the shared library \a filename. The library will be unloaded in the destructor. Note that \a filename does not need to include the (platform specific) file extension, so calling \code QLibrary lib( "mylib" ); \endcode is equivalent to calling \code QLibrary lib( "mylib.dll" ); \endcode on Windows, and \code QLibrary lib( "libmylib.so" ); \endcode on Unix. Specifying the extension is not recommended, since doing so introduces a platform dependency. If \a filename does not include a path, the library loader will look for the file in the platform specific search paths. \sa load() unload(), setAutoUnload() */ QLibrary::QLibrary( const QString& filename ) : libfile( filename ), aunload( TRUE ) { libfile.replace( '\\', '/' ); d = new QLibraryPrivate( this ); } /*! Deletes the QLibrary object. The library will be unloaded if autoUnload() is TRUE (the default), otherwise it stays in memory until the application exits. \sa unload(), setAutoUnload() */ QLibrary::~QLibrary() { if ( autoUnload() ) unload(); delete d; } /*! Returns the address of the exported symbol \a symb. The library is loaded if necessary. The function returns 0 if the symbol could not be resolved or the library could not be loaded. \code typedef int (*avgProc)( int, int ); avgProc avg = (avgProc) library->resolve( "avg" ); if ( avg ) return avg( 5, 8 ); else return -1; \endcode */ void *QLibrary::resolve( const char* symb ) { if ( !d->pHnd ) load(); if ( !d->pHnd ) return 0; void *address = d->resolveSymbol( symb ); return address; } /*! \overload Loads the library \a filename and returns the address of the exported symbol \a symb. Note that like the constructor, \a filename does not need to include the (platform specific) file extension. The library remains loaded until the process exits. The function returns 0 if the symbol could not be resolved or the library could not be loaded. This function is useful only if you want to resolve a single symbol, e.g. a function pointer from a specific library once: \code typedef void (*FunctionType)(); static FunctionType *ptrFunction = 0; static bool triedResolve = FALSE; if ( !ptrFunction && !triedResolve ) ptrFunction = QLibrary::resolve( "mylib", "mysymb" ); if ( ptrFunction ) ptrFunction(); else ... \endcode If you want to resolve multiple symbols, use a QLibrary object and call the non-static version of resolve(). \sa resolve() */ void *QLibrary::resolve( const QString &filename, const char *symb ) { QLibrary lib( filename ); lib.setAutoUnload( FALSE ); return lib.resolve( symb ); } /*! Returns TRUE if the library is loaded; otherwise returns FALSE. \sa unload() */ bool QLibrary::isLoaded() const { return d->pHnd != 0; } /*! Loads the library. Since resolve() always calls this function before resolving any symbols it is not necessary to call it explicitly. In some situations you might want the library loaded in advance, in which case you would use this function. */ bool QLibrary::load() { return d->loadLibrary(); } /*! Unloads the library and returns TRUE if the library could be unloaded; otherwise returns FALSE. This function is called by the destructor if autoUnload() is enabled. \sa resolve() */ bool QLibrary::unload() { if ( !d->pHnd ) return TRUE; #if !defined(QT_NO_LIBRARY_UNLOAD) if ( !d->freeLibrary() ) { # if defined(QT_DEBUG_COMPONENT) qWarning( "%s could not be unloaded", (const char*) QFile::encodeName(library()) ); # endif return FALSE; } # if defined(QT_DEBUG_COMPONENT) && QT_DEBUG_COMPONENT == 2 qWarning( "%s has been unloaded", (const char*) QFile::encodeName(library()) ); # endif d->pHnd = 0; #endif return TRUE; } /*! Returns TRUE if the library will be automatically unloaded when this wrapper object is destructed; otherwise returns FALSE. The default is TRUE. \sa setAutoUnload() */ bool QLibrary::autoUnload() const { return (bool)aunload; } /*! If \a enabled is TRUE (the default), the wrapper object is set to automatically unload the library upon destruction. If \a enabled is FALSE, the wrapper object is not unloaded unless you explicitly call unload(). \sa autoUnload() */ void QLibrary::setAutoUnload( bool enabled ) { aunload = enabled; } /*! Returns the filename of the shared library this QLibrary object handles, including the platform specific file extension. For example: \code QLibrary lib( "mylib" ); QString str = lib.library(); \endcode will set \e str to "mylib.dll" on Windows, and "libmylib.so" on Linux. */ QString QLibrary::library() const { if ( libfile.isEmpty() ) return libfile; QString filename = libfile; #if defined(Q_WS_WIN) if ( filename.findRev( '.' ) <= filename.findRev( '/' ) ) filename += ".dll"; #elif defined(Q_OS_MACX) if ( filename.find( ".dylib" ) == -1 ) filename += ".dylib"; #else if ( filename.find( ".so" ) == -1 ) { const int x = filename.findRev( "/" ); if ( x != -1 ) { QString path = filename.left( x + 1 ); QString file = filename.right( filename.length() - x - 1 ); filename = QString( "%1lib%2.so" ).arg( path ).arg( file ); } else { filename = QString( "lib%1.so" ).arg( filename ); } } #endif return filename; } #endif //QT_NO_LIBRARY