Question

I’m trying to run QueryPerformanceCounter() function from a particular process and get its return value to my C# application. Since those two processes (my application and the application i’m trying to affect) are different, what kind of strategy should i follow?

Answer 1

QueryPerformanceCounter is synchronized across all processes on a computer. You can just call it locally. That’s the same value that the other process would have received.

Update: Okay, you’re defending against cheaters. If they are hooking your process, then they are also going to hook your child processes, so spawning a helper process won’t help much.

One thing you can do is correlate multiple timers. For example,

QueryPerformanceCounter(&liStart);
dwStart = GetTickCount();
GetSystemTimeAsFileTime(&ftStart);
Sleep(1000);
QueryPerformanceCounter(&liStop);
dwStop = GetTickCount();
GetSystemTimeAsFileTime(&ftStop);

All four timers (QPC, GetTickCount, GetSystemTimeAsFileTime, and Sleep) should agree to within measurement error.

Another thing you can do is correlate against an external source. For example, you can write a function which obtains the time from the file system by creating a file and then asking for the file creation time. Correlate this against the other four timers. Other external sources are the sound and video hardware. For example, you can play a 1 second sound clip and see how long it takes. Or wait for the vertical blank and see if it matches the monitor refresh rate.