RegisterServiceCtrlHandlerEx

A service calls the RegisterServiceCtrlHandlerEx function to register a function to handle its service control requests.

This function supersedes the RegisterServiceCtrlHandler function. A service can use either function, but the new function supports user-defined context data, and the new handler function supports additional extended control codes.

SERVICE_STATUS_HANDLE RegisterServiceCtrlHandlerEx(
  LPCTSTR lpServiceName,                // name of service
  LPHANDLER_FUNCTION_EX lpHandlerProc,  // handler function
  LPVOID lpContext                      // user data
);

Parameters

lpServiceName

[in] Pointer to a null-terminated string that specifies the name of the service run by the calling thread. This is the service name that the service control program specified in the CreateService function when creating the service.

lpHandlerProc

[in] Pointer to the handler function to be registered. For more information, see HandlerEx.

lpContext

[in] User-defined data. This parameter, which is passed to the handler function, can help identify the service when multiple services share a process.

Return Values

If the function succeeds, the return value is a service status handle.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

The following error codes can be set by the service control manager. Other error codes can be set by the registry functions that are called by the service control manager.

Remarks

The ServiceMain function of a new service should immediately call the RegisterServiceCtrlHandlerEx function to register a control handler function with the control dispatcher. This enables the control dispatcher to invoke the specified function when it receives control requests for this service. The threads of the calling process can use the service status handle returned by this function to identify the service in subsequent calls to the SetServiceStatus function.

The RegisterServiceCtrlHandlerEx function must be called before the first SetServiceStatus call because RegisterServiceCtrlHandlerEx returns a service status handle for the caller to use so that no other service can inadvertently set this service status. In addition, the control handler must be in place to receive control requests by the time the service specifies the controls it accepts through the SetServiceStatus function.

When the control handler function is invoked with a control request, it must call SetServiceStatus to notify the service control manager of its current status, regardless of whether the status of the service has changed.

The service status handle does not have to be closed.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Header: Declared in Winsvc.h; include Windows.h.
  Library: Use Advapi32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows 2000.

See Also

Services Overview, Service Functions, CreateService, HandlerEx, ServiceMain, SetServiceStatus