C++ WMI UINT64 question

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4.67/5 (2 votes)

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I have a WMI class and im reading fine, I have a couple of small functins that read properties. Obviously each will have a different property type.

My question is what would you use to read the uint64?

For Strings:

C++

void WMIReader::ReadPropertyString( WCHAR* PropertyName, char* ReturnBuffer )
{
	VARIANT pProperty;
	ClassObject->Get( PropertyName, 0, &pProperty, 0, 0 );
	sprintf( ReturnBuffer, "%S", pProperty.bstrVal ); //bstrVal for strings
	VariantClear( &pProperty );
}

For Integers:

C++

void WMIReader::ReadPropertyInt( WCHAR* PropertyName, char* ReturnBuffer )
{
	VARIANT pProperty;
	ClassObject->Get( PropertyName, 0, &pProperty, 0, 0 );
	sprintf( ReturnBuffer, "%i", pProperty.intVal ); //intVal for integers
	VariantClear( &pProperty );
}

For UINT64:

C++

void WMIReader::ReadPropertyInt( WCHAR* PropertyName, char* ReturnBuffer )
{
    VARIANT pProperty;
    ClassObject->Get( PropertyName, 0, &pProperty, 0, 0 );
    sprintf( ReturnBuffer, "%i", pProperty.???? ); //What for uint64?
    VariantClear( &pProperty );
}

Thanks

Posted 14-May-12 1:11am

sjsteve33171

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5 solutions

Solution 1

Aah, you need a reference to the documentation.

Here you go http://msdn.microsoft.com/en-us/library/ms221627(v=vs.85)[^]

Alan.

Posted 14-May-12 1:40am

Alan N

Solution 2

Hi there, looking at VARIANT structure[^] my guess would be ullVal

I.e sizeof(unsigned long long) = 8 (win7 32bit app)

Posted 14-May-12 1:41am

enhzflep

Solution 3

Maybe i've done something wrong but i've done the following:

Read UINT64:

C++

void WMIReader::ReadPropertyUINT64( WCHAR* PropertyName, char* ReturnBuffer )
{
	VARIANT pProperty;
	ClassObject->Get( PropertyName, 0, &pProperty, 0, 0 );
	sprintf( ReturnBuffer, "%ld", pProperty.ulVal );
	VariantClear( &pProperty );
}

Query Logical Disk Class

C++

if( Reader->GetFirstDevice( L"Win32_LogicalDisk" ) )
{
	Reader->ReadPropertyUINT64( L"Size", pBuffer );
	strcpy( FoundDrive->FreeSpace, pBuffer );
}

Print out the Result

C++

Tools.AppendWindowText( pThis->m_StatusWindow, "Hard Disk: [%s\\] - Size: [%s]", CurrentDrive->DriveLetter, CurrentDrive->FreeSpace );

What i get is the following:
Hard Disk: [C:\] - Size: [4157124]

My Drive is:
Used: 138,660,515,840 bytes - 129gb
Free: 861,541,523,456 bytes - 802gb
Total: 1,000,202,039,296 bytes - 931gb

Posted 14-May-12 2:05am

sjsteve33171

Comments

enhzflep 14-May-12 9:36am

You've just asked for a (4 byte) unsigned long. Notice, you've only used 1 l - pProperty.ulVal (unsigned long)

you need 2 l's: pProperty.ullVal (unsigned long long)

Solution 5

My answer for UINT64 is: uVal

UINT64 means unsigned int** secPoint (i.e. point to *point)
that is (2 ^ 2)(4, unsigned int) * (2 ^ 6) 64KB = 2 ^ 8
So it is uVal.

void WMIReader::ReadPropertyInt( WCHAR* PropertyName, char* ReturnBuffer )
{
... ...
sprintf( ReturnBuffer, "%i", pProperty.???? ); //What for uint64?
VariantClear( &pProperty );
}

Posted 15-May-12 0:33am

smartguy

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sjsteve33171 · Accepted Answer · 2012-05-14T21:42:00

Ok turns out you would use the string to read a uint64 value. I ran wbemtest, queried my hard disk found the size value if you then edit the property it tells you the qualifier is "CIMTYPE CIM_STRING uint64".

I put this to the test and queried the size using the string reader and got:

Hard Disk: [C:\] - Size: [1000202039296]

Which matches what windows shows me as 1,000,202,039,296 bytes. Divide that by 1024 to get 976759804 KB. Divide that by 1024 to get 953866 MB. Divide that by 1024 to get 931 GB.

So for others wanting to read a uint64 use the bStrVal (String).