OpenService

The OpenService function opens a handle to an existing service.

SC_HANDLE OpenService(

SC_HANDLE hSCManager,	// handle to service control manager database
LPCTSTR lpServiceName,	// pointer to name of service to start
DWORD dwDesiredAccess	// type of access to service
);

Parameters

hSCManager

Identifies the service control manager (SCM) database. The OpenSCManager function returns this handle.

lpServiceName

Points to a null-terminated string that names the service to open. The maximum string length is 256 characters. The SCM database preserves the case of the characters, but service name comparisons are always case insensitive. A slash (/), backslash (\), comma, and space are invalid service name characters.

dwDesiredAccess

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. Any or all of the following service object access types can be specified:

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 ask the service control manager about 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.

STANDARD_RIGHTS_REQUIRED enables the following service object access types:

Standard rights	Description
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|WRITE_OWNER	Enables calling of the SetServiceObjectSecurity function to modify the security descriptor of the service object.

The dwDesiredAccess parameter can specify any or all of the following generic access types:

Generic access	Service access
GENERIC_READ	Combines the following access: STANDARD_RIGHTS_READ, SERVICE_QUERY_CONFIG, SERVICE_QUERY_STATUS, SERVICE_INTERROGATE, and SERVICE_ENUMERATE_DEPENDENTS.
GENERIC_WRITE	Combines the following access: STANDARD_RIGHTS_WRITE and SERVICE_CHANGE_CONFIG.
GENERIC_EXECUTE	Combines the following access: 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.

Errors

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.

Error code	Meaning
ERROR_ACCESS_DENIED	The specified service control manager database handle does not have access to the service.
ERROR_INVALID_HANDLE	The specified handle is invalid.
ERROR_INVALID_NAME	The specified service name is invalid.
ERROR_SERVICE_DOES_NOT_EXIST	The specified service does not exist.

Remarks

The calling process can use the returned handle to identify the service in the following functions, if the appropriate access rights are enabled:

ChangeServiceConfig
ControlService
DeleteService
EnumDependentServices
QueryServiceConfig
QueryServiceObjectSecurity
QueryServiceStatus
SetServiceObjectSecurity
StartService

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

See Also

ChangeServiceConfig, ControlService, CreateService, DeleteService, EnumDependentServices, OpenSCManager, QueryServiceConfig, QueryServiceObjectSecurity, QueryServiceStatus, SetServiceObjectSecurity, StartService

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