How does Resource Monitor get information for processes that already terminated?

Raymond ChenDecember 28, 2017Dec 28, 201712/28/17

How does the Resource Monitor program get information for processes that have already terminated? Try it: Run Task Manager, then go to the Performance tab. From there, click Open Resource Monitor. Now run another program, say, Notepad. Let Notepad run for a while, and then close it. Observe that there is still an entry for notepad.exe in ...

Why do I have to pass a valid page protection value to VirtualAlloc even if it ignores it?

Raymond ChenDecember 27, 2017Dec 27, 201712/27/17

The Virtual­Alloc function accepts a flProtect value, and even though the value is not used by MEM_RESET or MEM_RESET_UNDO, you still have to pass a valid value. (The documentation suggests PAGE_NO­ACCESS.) Why do you have to pass a valid value even if the system doesn't use it? This is an artifact of how the front-end parameter ...

Time travel is here, at least when it comes to debugging

Raymond ChenDecember 25, 2017Dec 25, 201712/25/17

At CppCon 2017, the Time Travel Debugging team (TTD) came through with a present for all the developers out there: A reverse debugging tool! Time Travel Debugging captures a trace of the program being executed so that the run can be replayed later. When you load the trace in the debugger, you can jump to any point in the program's ...

Exposing undefined behavior when trying to port code to another platform

Raymond ChenDecember 22, 2017Dec 22, 201712/22/17

A developer was porting some old Visual Studio code to another platform and found that the code was behavior strangely. Here's a simplified version of the code: This class is an array of references to integers. Each slot starts out uninitialized, but you can use methods (not shown here) to make each slot point to a particular integer, and you...

What’s the difference between VARIANT and VARIANTARG?

Raymond ChenDecember 21, 2017Dec 21, 201712/21/17

One of my colleagues asked me, "What's the difference between VARIANT and VARIANTARG?" If you look at the definitions in the oaidl.h header file, you'll see that VARIANTARG is just an alias for VARIANT. "Why have two names for the same thing?" The two structures are physically identical, but the rules surrounding them are different. This ...

How do I ShellExecute a file, but with a specific program instead of the default program?

Raymond ChenDecember 20, 2017Dec 20, 201712/20/17

The usual way to launch a file is to use Shell­Execute, which opens the file in the default program registered to handle that type of file. But what if you want to override the default? We saw some time ago that if you know the ProgId of the program you want to run, you can specify it in the lpClass of the SHELL­EXECUTE­INFO to ...