OpenService

The OpenService function opens an existing service.

SC_HANDLE OpenService(
  SC_HANDLE hSCManager,  // handle to SCM database
  LPCTSTR lpServiceName, // service name
  DWORD dwDesiredAccess  // access
);

Parameters

hSCManager

[in] Handle to the service control manager database. The OpenSCManager function returns this handle.

lpServiceName

[in] Pointer to a null-terminated string that specifies the name of the service to open. The maximum string length is 256 characters. The service control manager database preserves the case of the characters, but service name comparisons are always case insensitive. Forward-slash (/) and backslash (\) are invalid service name characters.

dwDesiredAccess

[in] Specifies the access to the service. Before granting the requested access, the system checks the access token of the calling process against the discretionary access-control list of the security descriptor associated with the service object.

The STANDARD_RIGHTS_REQUIRED constant enables the following object access types.

Standard rights	Description
ACCESS_SYSTEM_SECURITY	Enables calling of the QueryServiceObjectSecurity or SetServiceObjectSecurity function to access the SACL. The proper way to obtain this access is to enable the SE_SECURITY_NAME privilege in the caller's current access token, open the handle for ACCESS_SYSTEM_SECURITY access, and then disable the privilege.
DELETE	Enables calling of the DeleteService function to delete the service.
READ_CONTROL	Enables calling of the QueryServiceObjectSecurity function to query the security descriptor of the service object.
WRITE_DAC	Enables calling of the SetServiceObjectSecurity function to modify the Dacl member of the service object's security descriptor.
WRITE_OWNER	Enables calling of the SetServiceObjectSecurity function to modify the Owner and Group members of the service object's security descriptor.

You can specify any or all of the following service object access types.

Object access	Description
SERVICE_ALL_ACCESS	Includes STANDARD_RIGHTS_REQUIRED in addition to all of the access types listed in this table.
SERVICE_CHANGE_CONFIG	Enables calling of the ChangeServiceConfig function to change the service configuration.
SERVICE_ENUMERATE_DEPENDENTS	Enables calling of the EnumDependentServices function to enumerate all the services dependent on the service.
SERVICE_INTERROGATE	Enables calling of the ControlService function to ask the service to report its status immediately.
SERVICE_PAUSE_CONTINUE	Enables calling of the ControlService function to pause or continue the service.
SERVICE_QUERY_CONFIG	Enables calling of the QueryServiceConfig function to query the service configuration.
SERVICE_QUERY_STATUS	Enables calling of the QueryServiceStatus function to query the status of the service.
SERVICE_START	Enables calling of the StartService function to start the service.
SERVICE_STOP	Enables calling of the ControlService function to stop the service.
SERVICE_USER_DEFINED_CONTROL	Enables calling of the ControlService function to specify a user-defined control code.

You can specify any of the following generic access types.

Generic access	Service access
GENERIC_READ	Combines the following access types: STANDARD_RIGHTS_READ, SERVICE_QUERY_CONFIG, SERVICE_QUERY_STATUS, and SERVICE_ENUMERATE_DEPENDENTS.
GENERIC_WRITE	Combines the following access types: STANDARD_RIGHTS_WRITE and SERVICE_CHANGE_CONFIG.
GENERIC_EXECUTE	Combines the following access types: STANDARD_RIGHTS_EXECUTE, SERVICE_START, SERVICE_STOP, SERVICE_PAUSE_CONTINUE, and SERVICE_USER_DEFINED_CONTROL.

Return Values

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

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

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

Remarks

The returned handle is only valid for the process that called OpenService. It can be closed by calling the CloseServiceHandle function.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Header: Declared in Winsvc.h; include Windows.h.
  Library: Use Advapi32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.

See Also

Services Overview, Service Functions, ChangeServiceConfig, CloseServiceHandle, ControlService, CreateService, DeleteService, EnumDependentServices, OpenSCManager, QueryServiceConfig, QueryServiceObjectSecurity, QueryServiceStatus, SetServiceObjectSecurity, StartService