Starten eines Diensts
Um einen Dienst zu starten, öffnet ein Dienststeuerungsprogramm ein Handle für eine installierte Datenbank und gibt dann das Handle in einem Aufruf der StartService-Funktion an. Nach dem Starten des Diensts verwendet das Programm die Member der SERVICE_STATUS_PROCESS-Struktur , die von der QueryServiceStatusEx-Funktion zurückgegeben wird, um den Fortschritt des Diensts nachzuverfolgen.
Die DoStartSvc-Funktion im folgenden Beispiel zeigt, wie ein Dienst gestartet wird. Die Variable szSvcName ist eine globale Variable, die den Namen des zu startenden Diensts enthält. Das vollständige Beispiel, das diese Variable festlegt, finden Sie unter SvcControl.cpp.
//
// Purpose:
// Starts the service if possible.
//
// Parameters:
// None
//
// Return value:
// None
//
VOID __stdcall DoStartSvc()
{
SERVICE_STATUS_PROCESS ssStatus;
DWORD dwOldCheckPoint;
DWORD dwStartTickCount;
DWORD dwWaitTime;
DWORD dwBytesNeeded;
// Get a handle to the SCM database.
schSCManager = OpenSCManager(
NULL, // local computer
NULL, // servicesActive database
SC_MANAGER_ALL_ACCESS); // full access rights
if (NULL == schSCManager)
{
printf("OpenSCManager failed (%d)\n", GetLastError());
return;
}
// Get a handle to the service.
schService = OpenService(
schSCManager, // SCM database
szSvcName, // name of service
SERVICE_ALL_ACCESS); // full access
if (schService == NULL)
{
printf("OpenService failed (%d)\n", GetLastError());
CloseServiceHandle(schSCManager);
return;
}
// Check the status in case the service is not stopped.
if (!QueryServiceStatusEx(
schService, // handle to service
SC_STATUS_PROCESS_INFO, // information level
(LPBYTE) &ssStatus, // address of structure
sizeof(SERVICE_STATUS_PROCESS), // size of structure
&dwBytesNeeded ) ) // size needed if buffer is too small
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
// Check if the service is already running. It would be possible
// to stop the service here, but for simplicity this example just returns.
if(ssStatus.dwCurrentState != SERVICE_STOPPED && ssStatus.dwCurrentState != SERVICE_STOP_PENDING)
{
printf("Cannot start the service because it is already running\n");
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
// Save the tick count and initial checkpoint.
dwStartTickCount = GetTickCount();
dwOldCheckPoint = ssStatus.dwCheckPoint;
// Wait for the service to stop before attempting to start it.
while (ssStatus.dwCurrentState == SERVICE_STOP_PENDING)
{
// Do not wait longer than the wait hint. A good interval is
// one-tenth of the wait hint but not less than 1 second
// and not more than 10 seconds.
dwWaitTime = ssStatus.dwWaitHint / 10;
if( dwWaitTime < 1000 )
dwWaitTime = 1000;
else if ( dwWaitTime > 10000 )
dwWaitTime = 10000;
Sleep( dwWaitTime );
// Check the status until the service is no longer stop pending.
if (!QueryServiceStatusEx(
schService, // handle to service
SC_STATUS_PROCESS_INFO, // information level
(LPBYTE) &ssStatus, // address of structure
sizeof(SERVICE_STATUS_PROCESS), // size of structure
&dwBytesNeeded ) ) // size needed if buffer is too small
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
if ( ssStatus.dwCheckPoint > dwOldCheckPoint )
{
// Continue to wait and check.
dwStartTickCount = GetTickCount();
dwOldCheckPoint = ssStatus.dwCheckPoint;
}
else
{
if(GetTickCount()-dwStartTickCount > ssStatus.dwWaitHint)
{
printf("Timeout waiting for service to stop\n");
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
}
}
// Attempt to start the service.
if (!StartService(
schService, // handle to service
0, // number of arguments
NULL) ) // no arguments
{
printf("StartService failed (%d)\n", GetLastError());
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
else printf("Service start pending...\n");
// Check the status until the service is no longer start pending.
if (!QueryServiceStatusEx(
schService, // handle to service
SC_STATUS_PROCESS_INFO, // info level
(LPBYTE) &ssStatus, // address of structure
sizeof(SERVICE_STATUS_PROCESS), // size of structure
&dwBytesNeeded ) ) // if buffer too small
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
return;
}
// Save the tick count and initial checkpoint.
dwStartTickCount = GetTickCount();
dwOldCheckPoint = ssStatus.dwCheckPoint;
while (ssStatus.dwCurrentState == SERVICE_START_PENDING)
{
// Do not wait longer than the wait hint. A good interval is
// one-tenth the wait hint, but no less than 1 second and no
// more than 10 seconds.
dwWaitTime = ssStatus.dwWaitHint / 10;
if( dwWaitTime < 1000 )
dwWaitTime = 1000;
else if ( dwWaitTime > 10000 )
dwWaitTime = 10000;
Sleep( dwWaitTime );
// Check the status again.
if (!QueryServiceStatusEx(
schService, // handle to service
SC_STATUS_PROCESS_INFO, // info level
(LPBYTE) &ssStatus, // address of structure
sizeof(SERVICE_STATUS_PROCESS), // size of structure
&dwBytesNeeded ) ) // if buffer too small
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
break;
}
if ( ssStatus.dwCheckPoint > dwOldCheckPoint )
{
// Continue to wait and check.
dwStartTickCount = GetTickCount();
dwOldCheckPoint = ssStatus.dwCheckPoint;
}
else
{
if(GetTickCount()-dwStartTickCount > ssStatus.dwWaitHint)
{
// No progress made within the wait hint.
break;
}
}
}
// Determine whether the service is running.
if (ssStatus.dwCurrentState == SERVICE_RUNNING)
{
printf("Service started successfully.\n");
}
else
{
printf("Service not started. \n");
printf(" Current State: %d\n", ssStatus.dwCurrentState);
printf(" Exit Code: %d\n", ssStatus.dwWin32ExitCode);
printf(" Check Point: %d\n", ssStatus.dwCheckPoint);
printf(" Wait Hint: %d\n", ssStatus.dwWaitHint);
}
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
}
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