使用Registry-Key物件的控制碼

下表列出驅動程式可以在開啟索引鍵上執行的作業，以及要呼叫的適當常式。

作業	要呼叫的常式
檢查索引鍵的屬性，例如其名稱或其子機碼的數目。	ZwQueryKey
逐一查看索引鍵的子機碼，檢查每個索引鍵的屬性。	ZwEnumerateKey
檢查索引鍵值的屬性，包括值的資料。	ZwQueryValueKey
逐一查看索引鍵的值，並檢查每個值的屬性。	ZwEnumerateValueKey
設定與索引鍵相關聯之值的資料。	ZwSetValueKey
刪除金鑰。	ZwDeleteKey
刪除索引鍵值。	ZwDeleteValueKey

驅動程式完成其操作之後，它必須呼叫 ZwClose 以關閉控制碼，即使它已經呼叫 ZwDeleteKey 來刪除金鑰也一樣。 (刪除金鑰之後，所有開啟的控制碼都會變成無效，不過驅動程式仍然必須關閉 handle。)

下列程式碼範例說明如何開啟名為\Registry\Machine\Software\MyCompany\MyApp的機碼控制碼，然後擷取機碼資料並關閉控制碼。

//
// Get the frame location from the registry key
// HKLM\SOFTWARE\MyCompany\MyApp.
// For example: "FrameLocation"="X:\\MyApp\\Frames"
// 
HANDLE              handleRegKey = NULL;
for (int n = 0; n < 1; n++) 
{
    NTSTATUS           status = NULL;
    UNICODE_STRING     RegistryKeyName;
    OBJECT_ATTRIBUTES  ObjectAttributes;

    RtlInitUnicodeString(&RegistryKeyName, L"\\Registry\\Machine\\Software\\MyCompany\\MyApp");
    InitializeObjectAttributes(&ObjectAttributes, 
                               &RegistryKeyName,
                               OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
                               NULL,    // handle
                               NULL);
    status = ZwOpenKey(&handleRegKey, KEY_READ, &ObjectAttributes);

    // If the driver cannot open the key, the driver cannot continue. 
    // In this situation, the driver was probably set up incorrectly 
    // and worst case, the driver cannot stream.
    if( NT_SUCCESS(status) == FALSE ) 
    {
        break;
    }
    // The driver obtained the registry key.
    PKEY_VALUE_FULL_INFORMATION  pKeyInfo = NULL;
    UNICODE_STRING               ValueName;
    ULONG                        ulKeyInfoSize = 0;
    ULONG                        ulKeyInfoSizeNeeded = 0;

    // The driver requires the following value.
    RtlInitUnicodeString(&ValueName, L"FrameLocation");

    // Determine the required size of keyInfo.
    status = ZwQueryValueKey( handleRegKey,
                              &ValueName,
                              KeyValueFullInformation,
                              pKeyInfo,
                              ulKeyInfoSize,
                              &ulKeyInfoSizeNeeded );

    // The driver expects one of the following errors.
    if( (status == STATUS_BUFFER_TOO_SMALL) || (status == STATUS_BUFFER_OVERFLOW) )
    {
        // Allocate the memory required for the key.
        ulKeyInfoSize = ulKeyInfoSizeNeeded;
        pKeyInfo = (PKEY_VALUE_FULL_INFORMATION) ExAllocatePoolWithTag( NonPagedPool, ulKeyInfoSizeNeeded, g_ulTag);
        if( NULL == pKeyInfo )
        {
            break;
        }
        RtlZeroMemory( pKeyInfo, ulKeyInfoSize );

        // Get the key data.
        status = ZwQueryValueKey( handleRegKey,
                                  &ValueName,
                                  KeyValueFullInformation,
                                  pKeyInfo,
                                  ulKeyInfoSize,
                                  &ulKeyInfoSizeNeeded );
        if( (status != STATUS_SUCCESS) || (ulKeyInfoSizeNeeded != ulKeyInfoSize) || (NULL == pKeyInfo) )
        {
            break;
        }

        // Fill in the frame location if it has not been filled in already.
        if ( NULL == m_szwFramePath )
        {
            m_ulFramePathLength = pKeyInfo->DataLength;
            ULONG_PTR   pSrc = NULL;

            pSrc = (ULONG_PTR) ( (PBYTE) pKeyInfo + pKeyInfo->DataOffset);

            m_szwFramePath = (LPWSTR) ExAllocatePoolWithTag( NonPagedPool, m_ulFramePathLength, g_ulTag);
            if ( NULL == m_szwFramePath )
            {
                m_ulFramePathLength = 0;
                break;
            }

            // Copy the frame path.
            RtlCopyMemory(m_szwFramePath, (PVOID) pSrc, m_ulFramePathLength);
        }
        // The driver is done with the pKeyInfo.
        xFreePoolWithTag(pKeyInfo, g_ulTag);

    } // if( (status == STATUS_BUFFER_TOO_SMALL) || (status == STATUS_BUFFER_OVERFLOW) )
} // Get the Frame location from the registry key.

// All done with the registry.
if (NULL != handleRegKey)
{
    ZwClose(handleRegKey);
}

系統會快取記憶體中的金鑰變更，並每隔幾秒鐘將金鑰寫入磁片。 若要強制變更磁片的金鑰，請呼叫 ZwFlushKey。

若要透過更簡單的介面操作登錄，驅動程式也可以呼叫RtlXxx登錄Xxx常式。 如需詳細資訊，請參閱 登錄Run-Time程式庫常式。