Protecting certain functions to be used

[Antonio Linares]

If you allow your users to define and execute a macro or use the runtime Harbour compiler (hbcplr.lib), sometimes you may want to avoid the use of certain Harbour functions. This code allows you to protect the symbols that you don't want to be used:

Fill the array { "QOut" } to include all the symbols that you want to protect. Next version will allow to restore them when you want.

protect.prg

Code: Select all  Expand view

extern Dummy

function Main()

   Protect( { "QOut" } )
   ? Test()

return nil

function Test()

return 2 + 2    

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT HB_SIZE hb_parinfa( int iParamNum, HB_SIZE nArrayIndex );
extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );

HB_FUNC( DUMMY )
{
   hb_ret();  
}

HB_FUNC( PROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr =
         hb_dynsymSymbol( hb_dynsymFindName( "DUMMY" ) )->value.pFunPtr;
   }
}

#pragma ENDDUMP

[Antonio Linares]

Enhanced version: functions Protect() and UnProtect()

Code: Select all  Expand view

extern Dummy

function Main()

   Protect( { "Test" } )
   ? Test()
   UnProtect( { "Test" } )
   ? Test()

return nil

function Test()

return 2 + 2    

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT HB_SIZE hb_parinfa( int iParamNum, HB_SIZE nArrayIndex );
extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );
extern HB_EXPORT void hb_ret( void );

HB_FUNC( DUMMY )
{
   hb_ret();  
}

HB_FUNC( PROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->scope.pointer =
         hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr;

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr =
         hb_dynsymSymbol( hb_dynsymFindName( "DUMMY" ) )->value.pFunPtr;
   }
}

HB_FUNC( UNPROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr =
         hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->scope.pointer;
   }
}

#pragma ENDDUMP

[Antonio Linares]

Simpler and Harbour generates an error as the functions becomes undefined, even if the functions are linked. Once Unprotect()ed they become available again

Code: Select all  Expand view

function Main()

   Protect( { "FErase" } )
   FErase()

return nil

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT HB_SIZE hb_parinfa( int iParamNum, HB_SIZE nArrayIndex );
extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );

HB_FUNC( PROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->scope.pointer =
         hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr;

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr = NULL;
   }
}

HB_FUNC( UNPROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );

      hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->value.pFunPtr =
         hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) )->scope.pointer;
   }
}

#pragma ENDDUMP

[paquitohm]

Muchísimas gracias. Grandisimo aporte Antonio
Recuerdo, creo que en el foro de harbour users, una vez alguien pidió exactamente esto mismo

[Antonio Linares]

Gracias Paco,

versión simplificada:

Code: Select all  Expand view

function Main()

   HB_Protect( { "memoWrit" } )
   memoWrit()

return nil

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT HB_SIZE hb_parinfa( int iParamNum, HB_SIZE nArrayIndex );
extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );

HB_FUNC( HB_PROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );
      PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) );

      if( pSym )
      {
         pSym->scope.pointer = pSym->value.pFunPtr;
         pSym->value.pFunPtr = NULL;
      }
   }  
}

HB_FUNC( HB_UNPROTECT )
{
   int iLen = ( int ) hb_parinfa( 1, 0 );  
   int i;

   for( i = 0; i < iLen; i++ )
   {
      const char * szSymbolName = hb_parvc( 1, i + 1 );
      PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) );

      if( pSym )
         pSym->value.pFunPtr = pSym->scope.pointer;
   }
}

#pragma ENDDUMP

[Antonio Linares]

I just realized that scope.pointer is member of an union and not a member of a struct, so modifying scope.pointer will be affecting the scope of the symbol.

This would be the right way to do it:

Code: Select all  Expand view

function Main()

   local pFunPtr := HB_Protect( "memoWrit" )

   memoWrit()

   // later on
   // HB_Unprotect( "memoWrit", pFunPtr )

return nil

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );
extern HB_EXPORT void * hb_parptr( int iParam );
extern HB_EXPORT void hb_retptr( void * ptr );

HB_FUNC( HB_PROTECT )
{
   const char * szSymbolName = hb_parvc( 1 );
   PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) );

   if( pSym )
   {
      hb_retptr( pSym->value.pFunPtr );
      pSym->value.pFunPtr = NULL;
   }
}

HB_FUNC( HB_UNPROTECT )
{
   const char * szSymbolName = hb_parvc( 1 );
   PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( szSymbolName ) );

   if( pSym )
      pSym->value.pFunPtr = hb_parptr( 2 );
}

#pragma ENDDUMP

[Antonio Linares]

simpler:

Code: Select all  Expand view

function Main()

   local pFunPtr := HB_Protect( "memoWrit" )

   memoWrit()

   // later on
   // HB_Unprotect( "memoWrit", pFunPtr )

return nil

#pragma BEGINDUMP

#define _HB_API_INTERNAL_
#include <hbvmpub.h>

extern HB_EXPORT const char * hb_parvc( int iParam, ... );
extern HB_EXPORT PHB_DYNS hb_dynsymFindName( const char * szName );
extern HB_EXPORT PHB_SYMB hb_dynsymSymbol( PHB_DYNS pDynSym );
extern HB_EXPORT void * hb_parptr( int iParam );
extern HB_EXPORT void hb_retptr( void * ptr );

HB_FUNC( HB_PROTECT )
{
   PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( hb_parvc( 1 ) ) );

   if( pSym )
   {
      hb_retptr( pSym->value.pFunPtr );
      pSym->value.pFunPtr = NULL;
   }
}

HB_FUNC( HB_UNPROTECT )
{
   PHB_SYMB pSym = hb_dynsymSymbol( hb_dynsymFindName( hb_parvc( 1 ) ) );

   if( pSym )
      pSym->value.pFunPtr = hb_parptr( 2 );
}

#pragma ENDDUMP