implement NumFDs for Windows

process/process_windows.go

@@ -43,6 +43,7 @@ var (
 	procGetPriorityClass           = common.Modkernel32.NewProc("GetPriorityClass")
 	procGetProcessIoCounters       = common.Modkernel32.NewProc("GetProcessIoCounters")
 	procGetNativeSystemInfo        = common.Modkernel32.NewProc("GetNativeSystemInfo")
+	procGetProcessHandleCount      = common.Modkernel32.NewProc("GetProcessHandleCount")
 
 	processorArchitecture uint
 )
@@ -549,7 +550,18 @@ func (p *Process) NumCtxSwitchesWithContext(ctx context.Context) (*NumCtxSwitche
 }
 
 func (p *Process) NumFDsWithContext(ctx context.Context) (int32, error) {
-	return 0, common.ErrNotImplementedError
+	handle, err := windows.OpenProcess(processQueryInformation, false, uint32(p.Pid))
+	if err != nil {
+		return 0, err
+	}
+	defer windows.CloseHandle(handle)
+
+	var handleCount uint32
+	ret, _, err := procGetProcessHandleCount.Call(uintptr(handle), uintptr(unsafe.Pointer(&handleCount)))
+	if ret == 0 {
+		return 0, err
+	}
+	return int32(handleCount), nil
 }
 
 func (p *Process) NumThreadsWithContext(ctx context.Context) (int32, error) {