The Old New Thing

What does it mean when GetQueuedCompletionStatus return ERROR_SEM_TIMEOUT?

July 17, 2014 Jul 17, 2014 07/17/14

Raymond Chen

A customer asked for assistance interpreting a failure of the function. We are observing that is intermittently behaving as follows: That's all the information we have in our log files. We don't know the value of or , sorry. We realize that this is a rather vague question, but when this problem hits our machines, it causes our ...

How do I configure Windows Update programmatically?

July 16, 2014 Jul 16, 2014 07/16/14

Raymond Chen

First of all, normal programs shouldn't be messing with Windows Update configuration. That's something the user (or the user's administrator) decides. If you're an IT administrator, then you can use Group Policy to configure Windows Update on your network. But maybe you're a special case where the above remarks don't apply. Say you're a ...

Enumerating integer compositions (the return of the binomial coefficients)

July 14, 2014 Jul 14, 2014 07/14/14

Raymond Chen

In number theory, a composition of an integer is an ordered sequence of positive integers which sum to the target value. For example, the value 3 can be written as 3, 1+2, 2+1, or 1+1+1. You can think about the target number as a string of stars, and a composition is a way of breaking the stars into groups. For example, here are the ...

If I duplicate a handle, can I keep using the duplicate after closing the original?

July 11, 2014 Jul 11, 2014 07/11/14

Raymond Chen

A customer asked whether it was okay to use a duplicated handle even after the original handle was closed. Yes. That's sort of why you would duplicate it. Duplicating a handle creates a second handle which refers to the same underlying object as the original. Once that's done, the two handles are completely equivalent. There's no way to know...

Using the REFIID/void** pattern for returning COM objects for future-proofing and to avoid problems with dependencies

July 10, 2014 Jul 10, 2014 07/10/14

Raymond Chen

Suppose you have a function that creates a reference to a COM object: There are a few issues with this design. First of all, it requires that whoever uses your header file must have included first, since that's where is defined. You could solve that problem by putting at the top of , but that creates its own problems. For example, ...