Spotting problems with destructors for C++ temporaries

Raymond ChenApril 29, 2019Apr 29, 201904/29/19

Consider the unique_handle. It specializes std::unique_ptr to support Windows kernel handles. It lets you get all the niceties of std::unique_ptr with just a handful of lines of code. But then you have the problem of interoperating with the rest of the system. For example, how would you use a unique_handle to receive the result of a duplicati

How many ways are there to sort GUIDs? How much time do you have?

Raymond ChenApril 26, 2019Apr 26, 201904/26/19

Suppose you want to sort GUIDs, say because they are a key in an ordered map. How many ways are there to order them? Before we can even talk about how to order GUIDs, we need to figure out how we're going to represent them. You can take the view that a GUID is just an array of 16 bytes.¹ But the GUID structure itself groups them into four

How can I launch an unelevated process from my elevated process, redux

Raymond ChenApril 25, 2019Apr 25, 201904/25/19

Some time ago, I showed how you can launch an unelevated process from an elevated process by asking Explorer to launch the program on your behalf. There's another way which is a bit more direct, but it assumes that the thing you want to do can be done with a direct Create­Process call. In other words, if you need the system to look up the

A little program to look for files with inconsistent line endings

Raymond ChenApril 22, 2019Apr 22, 201904/22/19

I wrote this little program to look for files with inconsistent line endings. Maybe you'll find it useful. Probably not, but I'm posting it anyway. The Enumerate­Files method recursively enumerates the contents of the directory, but skips over hidden files, hidden directories, and directories with specific names. The main program takes t

On resolving the type vs member conflict in C++: The Color Color problem

Raymond ChenApril 19, 2019Apr 19, 201904/19/19

In C++, there are ambiguities when a member function has the same name as a type. Consider: Your project has a custom element, say like this: And now you are implementing the On­Theme­Changed method. This code doesn't compile. The word Style can mean multiple things: C++ unqualified name lookup in member functions searches the c

How arbitrary is the ArbitraryUserPointer in the TEB?

Raymond ChenApril 18, 2019Apr 18, 201904/18/19

There's a member of the NT_TIB structure called Arbitrary­User­Pointer. How arbitrary is this value? Can I use it for anything I want? This is another case of looking at the world through kernel-colored glasses. The Arbitrary­User­Pointer is arbitrary from the kernel's point of view, but that doesn't mean that it's available