GetProcessAffinityMask返回空进程关联

Question

In a very simple test console application, I tried to get process' affinity mask:

EDIT This code is incorrect. Problem solved. Please check comments and validated answer.

#include <cstdlib>
#include <cstdio>
#include <windows.h>

int main()
{
    while (1)
    {
        DWORD dwProcessAffinityMask = 0;
        DWORD dwSystemAffinityMask = 0;

        BOOL res = GetProcessAffinityMask(
            GetCurrentProcess(),
            (PDWORD_PTR)&dwProcessAffinityMask,
            (PDWORD_PTR)&dwSystemAffinityMask);

        printf("%d 0x%X 0x%X\n",
            res,
            dwProcessAffinityMask,
            dwSystemAffinityMask);

        Sleep(1000);
    }

    return 0;
}

Here is the output (64-bit executable, 64-bit system, meaning I do not fall into the WoW64 special case):

1 0x0 0x3
1 0x0 0x3
...

Running on my laptop, which has a 2 cores CPU, the resulting system's mask looks correct. But I don't understand the meaning of the dwProcessAffinityMask value I get here. Just for the sake of it, I also tried to toy around with the Task Manager by changing the process' affinity mask but the output remains the same.

This behavior doesn't seem to be documented .

Answer 1

Pass the address of DWORD_PTR variables rather than DWORD variables.

DWORD_PTR dwProcessAffinityMask;
DWORD_PTR dwSystemAffinityMask;

And remove those casts. They were a clear indication of what was wrong. When the compiler reports that you are passing parameters whose types don't match, correct the types rather than suppressing the error. The compiler already told you what was wrong, you just need to learn how to interpret its messages.