要启动一个服务，服务控制程序会打开一个已安装的数据库句柄，并在调用StartService函数时指定该句柄。启动服务后，程序使用QueryServiceStatusEx函数返回的SERVICE_STATUS_PROCESS结构的成员来跟踪服务的进度。
下面的示例代码中的DoStartSvc函数展示了如何启动一个服务。szSvcName变量是一个全局变量，包含要启动的服务的名称。要查看设置该变量的完整示例，请参考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);
}服务控制程序可以使用ControlService函数发送SERVICE_CONTROL_STOP请求来停止一个服务。如果服务控制管理器（SCM）接收到一个要求停止服务的SERVICE_CONTROL_STOP请求，它会通过将请求转发给服务的ServiceMain函数来指示服务停止运行。然而，如果SCM确定其他正在运行的服务依赖于指定的服务，它将不会转发停止请求。相反，它会返回ERROR_DEPENDENT_SERVICES_RUNNING错误。因此，要以编程方式停止这样的服务，您必须先枚举并停止其依赖的服务。
下面的示例代码中的DoStopSvc函数展示了如何停止一个服务及其依赖的服务。szSvcName变量是一个全局变量，包含要停止的服务的名称。要查看设置该变量的完整示例，请参考SvcControl.cpp。
//
// Purpose:
// Stops the service.
//
// Parameters:
// None
//
// Return value:
// None
//
VOID __stdcall DoStopSvc()
{
SERVICE_STATUS_PROCESS ssp;
DWORD dwStartTime = GetTickCount();
DWORD dwBytesNeeded;
DWORD dwTimeout = 30000; // 30-second time-out
DWORD dwWaitTime;
// 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_STOP |
SERVICE_QUERY_STATUS |
SERVICE_ENUMERATE_DEPENDENTS);
if (schService == NULL)
{
printf("OpenService failed (%d)\n", GetLastError());
CloseServiceHandle(schSCManager);
return;
}
// Make sure the service is not already stopped.
if ( !QueryServiceStatusEx(
schService,
SC_STATUS_PROCESS_INFO,
(LPBYTE)&ssp,
sizeof(SERVICE_STATUS_PROCESS),
&dwBytesNeeded ) )
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
goto stop_cleanup;
}
if ( ssp.dwCurrentState == SERVICE_STOPPED )
{
printf("Service is already stopped.\n");
goto stop_cleanup;
}
// If a stop is pending, wait for it.
while ( ssp.dwCurrentState == SERVICE_STOP_PENDING )
{
printf("Service stop pending...\n");
// 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 = ssp.dwWaitHint / 10;
if( dwWaitTime < 1000 )
dwWaitTime = 1000;
else if ( dwWaitTime > 10000 )
dwWaitTime = 10000;
Sleep( dwWaitTime );
if ( !QueryServiceStatusEx(
schService,
SC_STATUS_PROCESS_INFO,
(LPBYTE)&ssp,
sizeof(SERVICE_STATUS_PROCESS),
&dwBytesNeeded ) )
{
printf("QueryServiceStatusEx failed (%d)\n", GetLastError());
goto stop_cleanup;
}
if ( ssp.dwCurrentState == SERVICE_STOPPED )
{
printf("Service stopped successfully.\n");
goto stop_cleanup;
}
if ( GetTickCount() - dwStartTime > dwTimeout )
{
printf("Service stop timed out.\n");
goto stop_cleanup;
}
}
// If the service is running, dependencies must be stopped first.
StopDependentServices();
// Send a stop code to the service.
if ( !ControlService(
schService,
SERVICE_CONTROL_STOP,
(LPSERVICE_STATUS) &ssp ) )
{
printf( "ControlService failed (%d)\n", GetLastError() );
goto stop_cleanup;
}
// Wait for the service to stop.
while ( ssp.dwCurrentState != SERVICE_STOPPED )
{
Sleep( ssp.dwWaitHint );
if ( !QueryServiceStatusEx(
schService,
SC_STATUS_PROCESS_INFO,
(LPBYTE)&ssp,
sizeof(SERVICE_STATUS_PROCESS),
&dwBytesNeeded ) )
{
printf( "QueryServiceStatusEx failed (%d)\n", GetLastError() );
goto stop_cleanup;
}
if ( ssp.dwCurrentState == SERVICE_STOPPED )
break;
if ( GetTickCount() - dwStartTime > dwTimeout )
{
printf( "Wait timed out\n" );
goto stop_cleanup;
}
}
printf("Service stopped successfully\n");
stop_cleanup:
CloseServiceHandle(schService);
CloseServiceHandle(schSCManager);
}
BOOL __stdcall StopDependentServices()
{
DWORD i;
DWORD dwBytesNeeded;
DWORD dwCount;
LPENUM_SERVICE_STATUS lpDependencies = NULL;
ENUM_SERVICE_STATUS ess;
SC_HANDLE hDepService;
SERVICE_STATUS_PROCESS ssp;
DWORD dwStartTime = GetTickCount();
DWORD dwTimeout = 30000; // 30-second time-out
// Pass a zero-length buffer to get the required buffer size.
if ( EnumDependentServices( schService, SERVICE_ACTIVE,
lpDependencies, 0, &dwBytesNeeded, &dwCount ) )
{
// If the Enum call succeeds, then there are no dependent
// services, so do nothing.
return TRUE;
}
else
{
if ( GetLastError() != ERROR_MORE_DATA )
return FALSE; // Unexpected error
// Allocate a buffer for the dependencies.
lpDependencies = (LPENUM_SERVICE_STATUS) HeapAlloc(
GetProcessHeap(), HEAP_ZERO_MEMORY, dwBytesNeeded );
if ( !lpDependencies )
return FALSE;
__try {
// Enumerate the dependencies.
if ( !EnumDependentServices( schService, SERVICE_ACTIVE,
lpDependencies, dwBytesNeeded, &dwBytesNeeded,
&dwCount ) )
return FALSE;
for ( i = 0; i < dwCount; i++ )
{
ess = *(lpDependencies + i);
// Open the service.
hDepService = OpenService( schSCManager,
ess.lpServiceName,
SERVICE_STOP | SERVICE_QUERY_STATUS );
if ( !hDepService )
return FALSE;
__try {
// Send a stop code.
if ( !ControlService( hDepService,
SERVICE_CONTROL_STOP,
(LPSERVICE_STATUS) &ssp ) )
return FALSE;
// Wait for the service to stop.
while ( ssp.dwCurrentState != SERVICE_STOPPED )
{
Sleep( ssp.dwWaitHint );
if ( !QueryServiceStatusEx(
hDepService,
SC_STATUS_PROCESS_INFO,
(LPBYTE)&ssp,
sizeof(SERVICE_STATUS_PROCESS),
&dwBytesNeeded ) )
return FALSE;
if ( ssp.dwCurrentState == SERVICE_STOPPED )
break;
if ( GetTickCount() - dwStartTime > dwTimeout )
return FALSE;
}
}
__finally
{
// Always release the service handle.
CloseServiceHandle( hDepService );
}
}
}
__finally
{
// Always free the enumeration buffer.
HeapFree( GetProcessHeap(), 0, lpDependencies );
}
}
return TRUE;
}服务控制程序可以创建或修改与服务关联的DACL以控制访问。使用QueryServiceObjectSecurity函数可以检索与服务对象关联的DACL。使用SetServiceObjectSecurity函数可以设置DACL。对服务对象关联的SECURITY_DESCRIPTOR所做的任何更改都将持久存在，直到服务从系统中移除。
以下示例创建并设置了一个新的服务DACL。代码将一个访问控制项（ACE）合并到服务的现有DACL中。新的ACE将授予Guest账户对指定服务的启动、停止、删除和READ_CONTROL访问权限。可以通过传递给BuildExplicitAccessWithName函数的AccessPermissions参数修改对服务的访问权限。
szSvcName变量是一个全局变量，包含服务的名称。有关设置此变量的完整示例，请参阅SvcControl.cpp。
//
// Purpose:
// Updates the service DACL to grant start, stop, delete, and read
// control access to the Guest account.
//
// Parameters:
// None
//
// Return value:
// None
//
VOID __stdcall DoUpdateSvcDacl()
{
EXPLICIT_ACCESS ea;
SECURITY_DESCRIPTOR sd;
PSECURITY_DESCRIPTOR psd = NULL;
PACL pacl = NULL;
PACL pNewAcl = NULL;
BOOL bDaclPresent = FALSE;
BOOL bDaclDefaulted = FALSE;
DWORD dwError = 0;
DWORD dwSize = 0;
DWORD dwBytesNeeded = 0;
// 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, // SCManager database
szSvcName, // name of service
READ_CONTROL | WRITE_DAC); // access
if (schService == NULL)
{
printf("OpenService failed (%d)\n", GetLastError());
CloseServiceHandle(schSCManager);
return;
}
// Get the current security descriptor.
if (!QueryServiceObjectSecurity(schService,
DACL_SECURITY_INFORMATION,
&psd, // using NULL does not work on all versions
0,
&dwBytesNeeded))
{
if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
{
dwSize = dwBytesNeeded;
psd = (PSECURITY_DESCRIPTOR)HeapAlloc(GetProcessHeap(),
HEAP_ZERO_MEMORY, dwSize);
if (psd == NULL)
{
// Note: HeapAlloc does not support GetLastError.
printf("HeapAlloc failed\n");
goto dacl_cleanup;
}
if (!QueryServiceObjectSecurity(schService,
DACL_SECURITY_INFORMATION, psd, dwSize, &dwBytesNeeded))
{
printf("QueryServiceObjectSecurity failed (%d)\n", GetLastError());
goto dacl_cleanup;
}
}
else
{
printf("QueryServiceObjectSecurity failed (%d)\n", GetLastError());
goto dacl_cleanup;
}
}
// Get the DACL.
if (!GetSecurityDescriptorDacl(psd, &bDaclPresent, &pacl,
&bDaclDefaulted))
{
printf("GetSecurityDescriptorDacl failed(%d)\n", GetLastError());
goto dacl_cleanup;
}
// Build the ACE.
BuildExplicitAccessWithName(&ea, TEXT("GUEST"),
SERVICE_START | SERVICE_STOP | READ_CONTROL | DELETE,
SET_ACCESS, NO_INHERITANCE);
dwError = SetEntriesInAcl(1, &ea, pacl, &pNewAcl);
if (dwError != ERROR_SUCCESS)
{
printf("SetEntriesInAcl failed(%d)\n", dwError);
goto dacl_cleanup;
}
// Initialize a new security descriptor.
if (!InitializeSecurityDescriptor(&sd,
SECURITY_DESCRIPTOR_REVISION))
{
printf("InitializeSecurityDescriptor failed(%d)\n", GetLastError());
goto dacl_cleanup;
}
// Set the new DACL in the security descriptor.
if (!SetSecurityDescriptorDacl(&sd, TRUE, pNewAcl, FALSE))
{
printf("SetSecurityDescriptorDacl failed(%d)\n", GetLastError());
goto dacl_cleanup;
}
// Set the new DACL for the service object.
if (!SetServiceObjectSecurity(schService,
DACL_SECURITY_INFORMATION, &sd))
{
printf("SetServiceObjectSecurity failed(%d)\n", GetLastError());
goto dacl_cleanup;
}
else printf("Service DACL updated successfully\n");
dacl_cleanup:
CloseServiceHandle(schSCManager);
CloseServiceHandle(schService);
if(NULL != pNewAcl)
LocalFree((HLOCAL)pNewAcl);
if(NULL != psd)
HeapFree(GetProcessHeap(), 0, (LPVOID)psd);
}