Parsing a Value List

The following example parses a value list returned from the CLUSCTL_RESOURCE_TYPE_STORAGE_GET_AVAILABLE_DISKS control code.

#include <windows.h>

//////////////////////////////////////////////////////////////////////

#include "ClusDocEx.h"

//////////////////////////////////////////////////////////////////////

#ifndef _CLUSDOCEX_NODISSIGNATUREAVAILABLE_CPP
#define _CLUSDOCEX_NODISSIGNATUREAVAILABLE_CPP

//--------------------------------------------------------------------
// ClusDocEx_NodIsSignatureAvailable
//
// Tests whether a node can access a disk with a specified signature.
// 
// Arguments:
// IN HCLUSTER hCluster Cluster handle.
// IN HNODE hNode Handle to the node to query.
// IN DWORD dwSignature Signature to query for.
//
// Return Value:
// TRUE if the signature is available to the node
// FALSE if not (or if an error occurs)
//
//--------------------------------------------------------------------
BOOL ClusDocEx_NodIsSignatureAvailable
(
 IN HCLUSTER hCluster,
 IN HNODE hNode,
 IN DWORD dwSignature
)
{
 DWORD dwResult = ERROR_SUCCESS;

 DWORD cbPosition = 0;
 DWORD cbListSize = 0;
 BOOL bDiskFound = FALSE;

 LPVOID lpValueList = NULL;

 CLUSPROP_BUFFER_HELPER cbh;

 if( ( hCluster == NULL ) ||
 ( hNode == NULL ) )
 {
 dwResult = ERROR_BAD_ARGUMENTS;
 goto endf;
 }

// Get all disks available to the specified node.
 
 lpValueList = ClusDocEx_RtpGetControlCodeOutput( 
 L"Physical Disk",
 hCluster,
 hNode,
 CLUSCTL_RESOURCE_TYPE_STORAGE_GET_AVAILABLE_DISKS,
 &amp;cbListSize );

 if( lpValueList == NULL )
 {
 dwResult = GetLastError();
 goto endf;
 }


// Parse the buffer. The control code returns a value list.
// The entry for each disk begins with a CLUSPROP_DISK_SIGNATURE structure.

 cbh.pb = (PBYTE) lpValueList;

 while( 1 )
 {
 if( ( cbh.pDiskSignatureValue->Syntax.dw == CLUSPROP_SYNTAX_DISK_SIGNATURE ) &amp;&amp;
 ( cbh.pDiskSignatureValue->dw == dwSignature ) ) 
 {
 // Syntax indicates a CLUSPROP_DISK_SIGNATURE structure.
 // The signature found matches the specified signature.
 bDiskFound = TRUE;
 break;
 }
 else if( cbh.pSyntax->dw == CLUSPROP_SYNTAX_ENDMARK )
 // Reached the end of the list.
 break;

 // Add the size of the current entry to the position indicator
 cbPosition += ClusDocEx_ListEntrySize( cbh.pValue->cbLength );

 // Compare position indicator to the size of the list.
 // Adding sizeof( DWORD ) allows for the read operation at the
 // top of the loop.
 if( ( cbPosition + sizeof( DWORD ) ) > cbListSize )
 break;

 // Advance cbh
 cbh.pb += ClusDocEx_ListEntrySize( cbh.pValue->cbLength );

 }
 // End while.

endf:

 if( lpValueList != NULL )
 LocalFree( lpValueList );

 SetLastError( dwResult );

 return bDiskFound;
}
// end ClusDocEx_NodIsSignatureAvailable
//--------------------------------------------------------------------
#endif