The Old New Thing

How can I tell if a file is an image of some type?

April 30, 2015 Apr 30, 2015 04/30/15

Raymond Chen

The perceived type tells you what kind of file it is, for a very general sense of the word "kind".

Is the atom returned by RegisterClass(Ex) a "real" atom?

April 29, 2015 Apr 29, 2015 04/29/15

Raymond Chen

A customer was debugging some code that calls RegisterClass on a class that's already been registered. In this case, it was registered by another DLL in the same process. Normally, this wouldn't be a problem, because each DLL passes its own instance handle to RegisterClass so that there are no name collisions. However, in this case...

Access to a file's attributes is controlled by two things

April 28, 2015 Apr 28, 2015 04/28/15

Raymond Chen

We saw some time ago that permission to delete a file is granted either if you have DELETE access on the file, or if you have FILE_DELETE_CHILD access on the containing directory. File attributes behave in an analogous way. Permission to read a file's attributes is granted either if you have FILE_READ_ATTRIBUTES access on the file...

Wow, they really crammed a lot into those 410 transistors

April 27, 2015 Apr 27, 2015 04/27/15

Raymond Chen

Just an order of magnitude. Or three. Or more.

How do I extract the path to Control Panel from this shortcut so I can launch it?

April 27, 2015 Apr 27, 2015 04/27/15

Raymond Chen

You don't need to.

Why can't I have variadic COM methods?

April 24, 2015 Apr 24, 2015 04/24/15

Raymond Chen

COM methods cannot be variadic. Why not? Answer: Because the marshaler doesn't know when to stop. Suppose variadic COM methods were possible. And then you wrote this code: interface IVariadic { HRESULT Mystery([in] int code, ...); }; IVariadic *variadic = something; uint32_t ipaddr; HRESULT hr = variadic->Mystery(9, 192, 168, 1, 1...