c# - How do I GetModuleFileName() if I only have a window handle (hWnd)?

Question

I'm trying to get the name of the executable of a window that is outside my C# 2.0 application. My app currently gets a window handle (hWnd) using the GetForegroundWindow() call from "user32.dll".

From the digging that I've been able to do, I think I want to use the GetModuleFileNameEx() function (from PSAPI) to obtain the name, but GetModuleFileNameEx() requires a handle to a Process, not a Window.

Is it possible to get a process handle from a window handle? (Do I need to get the thread handle of the window first?)

EDITED the first sentence to make it clearer what I'm trying to do.

UPDATE! Here's the C# code that I found worked for me. The only caveat is occasionally it returns a file/path where the drive letter is a "?" instead of the actual drive letter (like "C"). -- Haven't figured out why yet.

[DllImport("user32.dll")]
static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

[DllImport("kernel32.dll")]
static extern IntPtr OpenProcess(UInt32 dwDesiredAccess, Int32 bInheritHandle, UInt32 dwProcessId);

[DllImport("psapi.dll")]
static extern uint GetModuleFileNameEx(IntPtr hProcess, IntPtr hModule, [Out] StringBuilder lpBaseName, [In] [MarshalAs(UnmanagedType.U4)] int nSize);

[DllImport("kernel32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool CloseHandle(IntPtr hObject);

private string GetWindowModuleFileName(IntPtr hWnd)
{
    uint processId = 0;
    const int nChars = 1024;
    StringBuilder filename = new StringBuilder(nChars);
    GetWindowThreadProcessId(hWnd, out processId);
    IntPtr hProcess = OpenProcess(1040, 0, processId);
    GetModuleFileNameEx(hProcess,IntPtr.Zero,filename,nChars);
    CloseHandle(hProcess);
    return (filename.ToString());
}

Answer 1

Been struggling with the same problem for an hour now, also got the first letter replaced by a ? by using GetModuleFileNameEx. Finaly came up with this solution using the System.Diagnostics.Process class.

[DllImport("user32.dll")]
public static extern IntPtr GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId);

void GetProcessPathFromWindowHandle(IntPtr hwnd)
{
   uint pid = 0;
   Win32.GetWindowThreadProcessId(hwnd, out pid);
   Process p = Process.GetProcessById((int)pid);
   return p.MainModule.FileName;
}