Add windows service name lookup to procstat input (#4811)

plugins/inputs/procstat/win_service_windows.go

@@ -0,0 +1,49 @@
+// +build windows
+
+package procstat
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/svc/mgr"
+)
+
+func getService(name string) (*mgr.Service, error) {
+	m, err := mgr.Connect()
+	if err != nil {
+		return nil, err
+	}
+	defer m.Disconnect()
+
+	srv, err := m.OpenService(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return srv, nil
+}
+
+func queryPidWithWinServiceName(winServiceName string) (uint32, error) {
+
+	srv, err := getService(winServiceName)
+	if err != nil {
+		return 0, err
+	}
+
+	var p *windows.SERVICE_STATUS_PROCESS
+	var bytesNeeded uint32
+	var buf []byte
+
+	if err := windows.QueryServiceStatusEx(srv.Handle, windows.SC_STATUS_PROCESS_INFO, nil, 0, &bytesNeeded); err != windows.ERROR_INSUFFICIENT_BUFFER {
+		return 0, err
+	}
+
+	buf = make([]byte, bytesNeeded)
+	p = (*windows.SERVICE_STATUS_PROCESS)(unsafe.Pointer(&buf[0]))
+	if err := windows.QueryServiceStatusEx(srv.Handle, windows.SC_STATUS_PROCESS_INFO, &buf[0], uint32(len(buf)), &bytesNeeded); err != nil {
+		return 0, err
+	}
+
+	return p.ProcessId, nil
+}