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Saturday, August 11, 2012

WINDOWS SERVICES - GETTING A LIST OF INSTALLED SERVICES


Want to get a list of active, inactive or all Windows services? 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;
Listing #1 : Delphi code. Download getlist (1.15 KB).
 
To get a list of all Windows services into a listbox named ListBox1:
 
ServiceGetList( '',
  SERVICE_WIN32,
  SERVICE_STATE_ALL,
  ListBox1.Items );
Listing #2 : Delphi code. Download demo (0.19 KB).

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