// MemoryStatus.c : servei que mira cuanta memoria queda lliure.

// To install this service on your operating system,
// you'll need to use the SC.EXE executable,
// which comes with the Win32 Platform SDK tools.
//
// Here is the command-line to install your MemoryStatus service:
//
//     sc create MemoryStatus binpath= c:\MyServices\MemoryStatus.exe
//
// To remove the service from the system, execute the following command:
//
//     sc delete MemoryStatus
//
// Autor : jeka_books@hotmail.com.
//
// URL : http://www.devx.com/cplus/Article/9857/0/page/1
//

// ****************************************************************************

// calen funcions Win32 :
#include <windows.h>
// per escriure a disc.
#include <stdio.h>

// periode entre 2 queries :
#define SLEEP_TIME 5000
// path to log file :
#define LOGFILE "C:\\MyServices\\memstatus.txt"

// ****************************************************************************

// Global vars :

SERVICE_STATUS           ServiceStatus ;
SERVICE_STATUS_HANDLE    hStatus ;

// Forward declarations :

void ServiceMain ( int argc, char ** argv ) ;
void ControlHandler ( DWORD request ) ;
int  InitService ( ) ;

// ****************************************************************************

// Define the main function, which is the entry point to the program.
// In case of services, the code for main will be surprisingly short,
// since it just creates the dispatch table and starts the control dispatcher

void main () {

     SERVICE_TABLE_ENTRY ServiceTable [ 2 ] ;

     ServiceTable [0].lpServiceName = "MemoryStatus" ;
     ServiceTable [0].lpServiceProc = (LPSERVICE_MAIN_FUNCTION) ServiceMain ;

     ServiceTable [1].lpServiceName = NULL ;
     ServiceTable [1].lpServiceProc = NULL ;

     // Start the control dispatcher thread for our service
     StartServiceCtrlDispatcher ( ServiceTable ) ;

} ;

// ****************************************************************************

int WriteToLog ( char * str ) {

     FILE * log ;
     log = fopen ( LOGFILE, "a+" ) ;
     if ( log == NULL )
        return -1 ;
     fprintf ( log, "%s\n", str ) ;
     fclose ( log ) ;
     return 0 ;

} ; // WriteToLog

// ****************************************************************************

// Service initialization
int InitService ( ) {

 int result;

     result = WriteToLog ( "Monitoring started." ) ;
     return ( result ) ;

} ;  // InitService

// ****************************************************************************

void ControlHandler ( DWORD request ) {

     switch ( request ) {

          case SERVICE_CONTROL_STOP:

               WriteToLog ("Monitoring stopped." ) ;

               ServiceStatus.dwWin32ExitCode = 0 ;
               ServiceStatus.dwCurrentState = SERVICE_STOPPED ;
               SetServiceStatus ( hStatus, & ServiceStatus ) ;
               return;

          case SERVICE_CONTROL_SHUTDOWN:

             WriteToLog ("Monitoring stopped." ) ;

             ServiceStatus.dwWin32ExitCode = 0 ;
             ServiceStatus.dwCurrentState = SERVICE_STOPPED ;
             SetServiceStatus ( hStatus, & ServiceStatus) ;
             return;

          default:
             break ;

     } ; // switch

     // Report current status
     SetServiceStatus ( hStatus, & ServiceStatus ) ;

     return ;

} ;  // ControlHandler

// ****************************************************************************

// Initialize the ServiceStatus structure
// specifying the service characteristics and its current state.
// Each ServiceStatus structure fields has a purpose:
//
//    * dwServiceType: indicates the type of service.
// Author Win32 service; assign the SERVICE_WIN32 value.
//
//    * dwCurrentState: specifies the current state of the service.
// Since initialization of a service has not been finished at this point,
// set the SERVICE_START_PENDING status.
//
//    * dwControlsAccepted: this field will inform the SCM
// which fields the service accepts.
// In this case, allow STOP and SHUTDOWN requests.
// Handling control requests is discussed in Step 3.
//
//    * dwWin32ExitCode and dwServiceSpecificExitCode: these fields
// are useful when you are terminating the service
// and want to report the detailed exit code.
// Since, you will initialize the service and will not exit, assign 0 values.
//
//    * dwCheckPoint and dwWaitHint: these fields indicate the progress
// of a service when it performs an initialization longer than 30 seconds .
// This service has a very short initialization procedure,
// so assign 0 values to both fields.

void ServiceMain ( int argc, char ** argv ) {

 int error ;
 MEMORYSTATUS memory ;
 int result ;

     ServiceStatus.dwServiceType = SERVICE_WIN32 ;
     ServiceStatus.dwCurrentState = SERVICE_START_PENDING ;
     ServiceStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN ;
     ServiceStatus.dwWin32ExitCode = 0 ;
     ServiceStatus.dwServiceSpecificExitCode = 0 ;
     ServiceStatus.dwCheckPoint = 0 ;
     ServiceStatus.dwWaitHint = 0 ;

     hStatus = RegisterServiceCtrlHandler ( "MemoryStatus",
                       (LPHANDLER_FUNCTION) ControlHandler ) ;

     if ( hStatus == (SERVICE_STATUS_HANDLE) 0 )
     {
          // Registering Control Handler failed
          return ;
     }

     // Initialize Service
     error = InitService () ;
     if ( error )
     {
          // Initialization failed
          ServiceStatus.dwCurrentState = SERVICE_STOPPED ;
          ServiceStatus.dwWin32ExitCode = -1 ;
          SetServiceStatus ( hStatus, & ServiceStatus ) ;
          return ;
     }

     // We report the running status to SCM.
     ServiceStatus.dwCurrentState = SERVICE_RUNNING ;
     SetServiceStatus ( hStatus, & ServiceStatus ) ;

     // The worker loop of a service
     while ( ServiceStatus.dwCurrentState == SERVICE_RUNNING )
     {
          char buffer [ 16 ] ;
          GlobalMemoryStatus ( & memory ) ;
          sprintf ( buffer, "%d", memory.dwAvailPhys ) ;
          result = WriteToLog ( buffer ) ;
          if ( result )
          {
               ServiceStatus.dwCurrentState = SERVICE_STOPPED ;
               ServiceStatus.dwWin32ExitCode = -1 ;
               SetServiceStatus ( hStatus, & ServiceStatus ) ;
               return;
          }

          Sleep ( SLEEP_TIME ) ;
     }
     return ;

} ;  // ServiceMain

// ****************************************************************************