Getting a list of installed services

Problem/Question/Abstract:

Want to get a list of active, inactive or all Windows services?

Answer:

Following function can help you to do this, but be sure to read other Windows services related tips for details.

const
  //
  // Service Types
  //
  SERVICE_KERNEL_DRIVER = $00000001;
  SERVICE_FILE_SYSTEM_DRIVER = $00000002;
  SERVICE_ADAPTER = $00000004;
  SERVICE_RECOGNIZER_DRIVER = $00000008;

  SERVICE_DRIVER =
    (SERVICE_KERNEL_DRIVER or
    SERVICE_FILE_SYSTEM_DRIVER or
    SERVICE_RECOGNIZER_DRIVER);

  SERVICE_WIN32_OWN_PROCESS = $00000010;
  SERVICE_WIN32_SHARE_PROCESS = $00000020;
  SERVICE_WIN32 =
    (SERVICE_WIN32_OWN_PROCESS or
    SERVICE_WIN32_SHARE_PROCESS);

  SERVICE_INTERACTIVE_PROCESS = $00000100;

  SERVICE_TYPE_ALL =
    (SERVICE_WIN32 or
    SERVICE_ADAPTER or
    SERVICE_DRIVER or
    SERVICE_INTERACTIVE_PROCESS);

uses WinSvc;

//-------------------------------------
// Get a list of services
//
// return TRUE if successful
//
// sMachine:
//   machine name, ie: \\SERVER
//   empty = local machine
//
// dwServiceType
//   SERVICE_WIN32,
//   SERVICE_DRIVER or
//   SERVICE_TYPE_ALL
//
// dwServiceState
//   SERVICE_ACTIVE,
//   SERVICE_INACTIVE or
//   SERVICE_STATE_ALL
//
// slServicesList
//   TStrings variable to storage
//

function ServiceGetList(
  sMachine: string;
  dwServiceType,
  dwServiceState: DWord;
  slServicesList: TStrings)
  : boolean;
const
  //
  // assume that the total number of
  // services is less than 4096.
  // increase if necessary
  cnMaxServices = 4096;

type
  TSvcA = array[0..cnMaxServices]
    of TEnumServiceStatus;
  PSvcA = ^TSvcA;

var
  //
  // temp. use
  j: integer;

  //
  // service control
  // manager handle
  schm: SC_Handle;

  //
  // bytes needed for the
  // next buffer, if any
  nBytesNeeded,

  //
  // number of services
  nServices,

  //
  // pointer to the
  // next unread service entry
  nResumeHandle: DWord;

  //
  // service status array
  ssa: PSvcA;
begin
  Result := false;

  // connect to the service
  // control manager
  schm := OpenSCManager(
    PChar(sMachine),
    nil,
    SC_MANAGER_ALL_ACCESS);

  // if successful...
  if (schm > 0) then
  begin
    nResumeHandle := 0;

    New(ssa);

    EnumServicesStatus(
      schm,
      dwServiceType,
      dwServiceState,
      ssa^[0],
      SizeOf(ssa^),
      nBytesNeeded,
      nServices,
      nResumeHandle);

    //
    // assume that our initial array
    // was large enough to hold all
    // entries. add code to enumerate
    // if necessary.
    //

    for j := 0 to nServices - 1 do
    begin
      slServicesList.
        Add(StrPas(
        ssa^[j].lpDisplayName));
    end;

    Result := true;

    Dispose(ssa);

    // close service control
    // manager handle
    CloseServiceHandle(schm);
  end;
end;

To get a list of all Windows services into a listbox named ListBox1:

ServiceGetList('', SERVICE_WIN32, SERVICE_STATE_ALL, ListBox1.Items);