Re: [ctypes-users] finding PID through handle with Ctypes

[eryk s. <er...@gm...>]

On Mon, Aug 14, 2017 at 7:57 PM, Michael C
<mys...@gm...> wrote:
>
> I am trying to get the PID of a process given its name. I acquire the
> handle, and then feed it to the ctypes function hoping it would return the
> PID, but it returns 0!
>
> import ctypes
>
> window_name = 'chrome.exe'
> User32 = ctypes.WinDLL('User32', use_last_error=True)
> Kernel32 = ctypes.WinDLL('Kernel32', use_last_error=True)
> handle = User32.FindWindowW(None, window_name )
> print(Kernel32.GetProcessId(handle))

GetProcessId [1] takes a kernel Process handle, but you're passing it
a user Window handle. Ask the window manager instead. Every Window is
owned by a Thread, and every Thread belongs to a Process.
user32.GetWindowThreadProcessId [2] returns both identifiers. The
second argument to this function is a pointer to a DWORD, to which it
writes the Process ID.

[1]: https://msdn.microsoft.com/en-us/library/ms683215
[2]: https://msdn.microsoft.com/en-us/library/ms633522