/****************************************************************************
** $Id:  qt/qlibrary.cpp   3.0.3   edited Jan 30 23:03 $
**
** Implementation of QLibrary class
**
** Created : 2000-01-01
**
** Copyright (C) 2000 Trolltech AS.  All rights reserved.
**
** This file is part of the kernel 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.
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** Contact info@trolltech.com if any conditions of this licensing are
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**********************************************************************/


#include <private/qlibrary_p.h>

#include <qregexp.h>

// 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

// KAI C++ has at the moment problems with unloading the Qt plugins. So don't
// unload them as a workaround for now.
#if defined(Q_CC_KAI) || defined(Q_OS_MAC) || defined(Q_OS_HPUX)
#define QT_NO_LIBRARY_UNLOAD
#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

  \brief The QLibrary class provides a wrapper for handling shared libraries.

  \mainclass

  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 e.g. 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 become a null
  pointer. Upon destruction of the QLibrary object 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. 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( QRegExp("\\\\"), "/" );
    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 is exited.

  \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 a null pointer 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 a null pointer 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( "foo", "function" );

  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 this function explicitly. In
  some situations you might want the library loaded in advance, in
  which case you would call 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;

// ### this is a hack to solve problems with plugin unloading und KAI C++
// (other compilers may have the same problem)
#if !defined(QT_NO_LIBRARY_UNLOAD)
    if ( !d->freeLibrary() ) {
#if defined(QT_DEBUG_COMPONENT)
	qWarning( "%s could not be unloaded.", library().latin1() );
#endif
	return FALSE;
#else
	return TRUE;
#endif
#if !defined(QT_NO_LIBRARY_UNLOAD)
    }

#if defined(QT_DEBUG_COMPONENT) && QT_DEBUG_COMPONENT == 2
    qWarning( "%s has been unloaded.", library().latin1() );
#endif

    d->pHnd = 0;
    return TRUE;
#endif
}

/*!
  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.find( ".dll", 0, FALSE ) == -1 )
	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;
}
