Détermination de la taille du Registre

Sur Windows 2000, il est courant qu’un utilitaire d’installation case activée la taille actuelle et maximale du Registre afin de déterminer s’il y a suffisamment d’espace disponible pour les nouvelles données qu’il ajoutera. Cet exemple montre comment effectuer cette opération par programmation à l’aide du compteur de performances « % de quota de Registre en cours d’utilisation » dans l’objet System.

L’exemple suivant utilise l’assistant de données de performances (PDH) pour obtenir la valeur du compteur : il doit être lié à Pdh.lib. PDH est un ensemble d’API de haut niveau utilisées pour obtenir des données de performances.

Notes

Il n’est pas nécessaire d’implémenter cette taille de registre case activée sur Windows Server 2003 ou Windows XP, car ils n’ont pas de limite de quota de Registre.

 

//*******************************************************************
// 
//  Determines the current and maximum registry size.
//
//*******************************************************************

#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include <pdh.h>

PDH_STATUS GetRegistrySize( LPTSTR szMachineName, 
    LPDWORD lpdwCurrentSize, LPDWORD lpdwMaximumSize );

//*******************************************************************
// 
//  Entry point for the program. This function demonstrates how to
//  use the GetRegistrySize function implemented below.
// 
//  It will use the first argument, if present, as the name of the
//  computer whose registry you wish to determine. If unspecified,
//  it will use the local computer.
//*******************************************************************

int _tmain( int argc, TCHAR *argv[] ) 
{

    LPTSTR      szMachineName  = NULL;
    PDH_STATUS  pdhStatus      = 0;
    DWORD       dwCurrent      = 0;
    DWORD       dwMaximum      = 0;

    // Allow a computer name to be specified on the command line.
    if ( argc > 1 )
        szMachineName = argv[1];

    // Get the registry size.
    pdhStatus=GetRegistrySize(szMachineName, &dwCurrent, &dwMaximum);

    // Print the results.
    if ( pdhStatus == ERROR_SUCCESS ) 
    {
        _tprintf( TEXT("Registry size: %ld bytes\n"), dwCurrent );
        _tprintf( TEXT("Max registry size: %ld bytes\n"), dwMaximum );

    } 
    else 
    {
        // If the operation failed, print the PDH error message.
        LPTSTR szMessage = NULL;

        FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER |
            FORMAT_MESSAGE_FROM_HMODULE,
            GetModuleHandle( TEXT("PDH.DLL") ), pdhStatus,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
            szMessage, 0, NULL );

        _tprintf( TEXT("GetRegistrySize failed:  %s"), szMessage );

        LocalFree( szMessage );
    }

    return 0;
}

//*******************************************************************
// 
//  Retrieves the current and maximum registry size. It gets this
//  information from the raw counter values for the "% Registry Quota 
//  In Use" performance counter within the System object.
// 
//  PARAMETERS:   
//      szMachineName - Null-terminated string that specifies the
//          name of the computer whose registry you wish to query.
//          If this parameter is NULL, the local computer is used.
// 
//      lpdwCurrentSize - Receives the current registry size.
// 
//      lpdwMaximumSize - Receives the maximum registry size.
// 
//  RETURN VALUE: 
//      ERROR_SUCCESS if successful. Otherwise, the function
//      returns a PDH error code. These error codes can be
//      found in PDHMSG.H. A textual error message can be
//      retrieved from PDH.DLL using the FormatMessage function.
// 
//******************************************************************

PDH_STATUS GetRegistrySize( LPTSTR szMachineName, 
    LPDWORD lpdwCurrentSize, LPDWORD lpdwMaximumSize ) 
{
    PDH_STATUS  pdhResult   = 0;
    TCHAR       szCounterPath[1024];
    DWORD       dwPathSize  = 1024;
    PDH_COUNTER_PATH_ELEMENTS pe;
    PDH_RAW_COUNTER pdhRawValues;
    HQUERY      hQuery      = NULL;
    HCOUNTER    hCounter    = NULL;
    DWORD       dwType      = 0;

    // Open PDH query
    pdhResult = PdhOpenQuery( NULL, 0, &hQuery );
    if ( pdhResult != ERROR_SUCCESS )
        return pdhResult;

    __try 
    {
        // Create counter path
        pe.szMachineName     = szMachineName;
        pe.szObjectName      = TEXT("System");
        pe.szInstanceName    = NULL;
        pe.szParentInstance  = NULL;
        pe.dwInstanceIndex   = 1;
        pe.szCounterName     = TEXT("% Registry Quota In Use");

        pdhResult = PdhMakeCounterPath( &pe, szCounterPath, 
            &dwPathSize, 0 );
        if ( pdhResult != ERROR_SUCCESS )
            __leave;

        // Add the counter to the query
        pdhResult=PdhAddCounter(hQuery, szCounterPath, 0, &hCounter);
        if ( pdhResult != ERROR_SUCCESS ) 
            __leave;

        // Run the query to collect the performance data
        pdhResult = PdhCollectQueryData( hQuery );
        if ( pdhResult != ERROR_SUCCESS ) 
            __leave;

        // Retrieve the raw counter data:
        //    The dividend (FirstValue) is the current registry size
        //    The divisor (SecondValue) is the maximum registry size
        ZeroMemory( &pdhRawValues, sizeof(pdhRawValues) );
        pdhResult = PdhGetRawCounterValue( hCounter, &dwType,
            &pdhRawValues );
        if ( pdhResult != ERROR_SUCCESS )
            __leave;

        // Store the sizes in variables.
        if ( lpdwCurrentSize )
            *lpdwCurrentSize = (DWORD) pdhRawValues.FirstValue;
         
        if ( lpdwMaximumSize )
            *lpdwMaximumSize = (DWORD) pdhRawValues.SecondValue;

    } 
    __finally 
    {
        // Close the query
        PdhCloseQuery( hQuery );
    }

    return 0;
}