gnat/linux:setitimer

[TIlman Glotzner <Tilman.Gloetzner@etas.co.kr>]

Hello,

below my attempt to connect the linux system timer to an ada program.
1) In the process list, I see the program distributed over 5
processes. Each signal handler is mapped onto one process. One
process is probably needed for the main program. On which part
of the program are the other 2 processes mapped to ?

2) When the timer expires, the timer signal (SIGALRM) is not catched
by the signal handler.  The signal handlers itselves apparrently work as
the handlers react to signals sent by a unix kill command. As
process number I need to give the PID of the appropriate signal
handler. I suspect that the signal is sent to the process that
started the itimer. As the signal signal handlers  run as
separated processes, the SIGALRM signal issued from the itimer does not 
reach the signal handlers. What do I need to do to make it work ?

3) Is there a unix utility that allows me to monitor signals,
 i.e. which program issues which signal, and which program catches it ?

4) I first tried to import the system call "setitimer", and hand over
setitimer's parameters by access types(ITimervalPtrs'address). The
program also compiles if handing over the variables directly (not
references to the variables). Is gnat/ada doing a parameter conversion to
a reference implicitly for me ?

Thank you,

Tilman

--------------------------------------------------------------
-- Filename: timer.ads
--------------------------------------------------------------
with Type_Defs,System.Address_To_Access_Conversions,Ada.Interrupts.Names;
use Type_Defs,Ada.Interrupts, Ada.Interrupts.Names;

package Timer is

   -- Timers run in real time.
   ITIMER_REAL: constant := 0;

   -- Timers run only when the process is executing.
   ITIMER_VIRTUAL: constant := 1;

   --  Timers run when the process is executing and when
   --  the system is executing on behalf of the process.
   ITIMER_PROF: constant := 2;

   type T_Time is new Long_Integer;

   type T_Timeval is record
      Tv_Sec : T_Time;        -- seconds
      Tv_Usec: T_Time;        -- microseconds
   end record;

   type T_Itimerval is record
      It_Interval: T_Timeval;    -- next value
      It_Value:    T_Timeval;    -- current Value
   end record;

   package TimevalPtrs is new System.Address_To_Access_Conversions( 
T_Timeval );
   package ITimervalPtrs is new System.Address_To_Access_Conversions( 
T_Itimerval );


  
   protected SignalHandler is
      -- SIGINT (Control-C) signals will be intercepted by
      -- HandleControlC
      procedure HandleControlPwrFail;
      pragma Attach_Handler( HandleControlPwrFail, SIGPWR );

      -- Signal handler for SIGALARM issued from a timer
      procedure HandleAlarm;
      pragma Attach_Handler( HandleAlarm,  SIGALRM );
   end SignalHandler;

   procedure Setitimer(RC:out  Integer; Which: in Integer ;
                       Value: in out T_Itimerval;
                       Ovalue: in out T_Itimerval);
   pragma Import (C,Setitimer);
  pragma Import_Valued_Procedure(Setitimer);

end Timer;

--------------------------------------------------------------
-- Filename: timer.adb
--------------------------------------------------------------
with Timer, System.Address_To_Access_Conversions,Text_IO;
use Timer,Text_Io;
package body Timer is
   protected body SignalHandler is
      -- This protected type contains all our signal handlers
      procedure HandleAlarm is
         -- Alarm signal handler
      begin
         Put_Line( "HandleAlarm: ALARMSIG catched." );
      end HandleAlarm;

      procedure HandleControlPwrFail is
         -- Power fail signal handler
      begin
         Put_Line( "HandleControlPwrFail activated by catched signal SIGPWR" 
);
      end HandleControlPwrFail;
   end SignalHandler;
end Timer;

--------------------------------------------------------------
-- Filename: timer_test.adb
--------------------------------------------------------------
with Text_Io,Timer,Ada.Interrupts,Ada.Interrupts.Names;
use Text_Io,Timer,Ada.Interrupts,Ada.Interrupts.Names;

procedure Timer_Test_B is
   Handler : Parameterless_Handler;
   Counter: Integer := 0;
   Timer: aliased T_Itimerval := ((0,10000),(0,10000));
   OldTimer:  aliased T_Itimerval := ((0,0),(0,0));
   I: Integer := 20;
begin
   Put_Line("Timer_Test");
   Put_Line("==========");


   Timer.It_Value.Tv_Sec := 0;
   Timer.It_Value.Tv_Usec := 100000;
   Timer.It_Interval.Tv_Sec  := 0;
   Timer.It_Interval.Tv_Usec := 100000;

   if Is_Reserved( SIGALRM ) then
      Put_Line( "The ALARMSIG handler is reserved" );
   else
      Put_Line( "The ALARMSIG handler isn't reserved" );
  end if;

   if Is_Attached( SIGALRM ) then
      Put_Line( "The ALARMSIG handler is attached" );
   else
      Put_Line( "The ALARMSIG handler isn't attached" );
   end if;

   if Is_Reserved( SIGPWR ) then
      Put_Line( "The SIGPWR handler is reserved" );
   else
      Put_Line( "The SIGPWR handler isn't reserved" );
   end if;

   if Is_Attached( SIGPWR ) then
      Put_Line( "The SIGPWR handler is attached" );
   else
      Put_Line( "The SIGPWR handler isn't attached" );
   end if;

   New_Line;
   Put_Line( "Testing SIGALRM handler..." );

   Handler := Current_Handler( SIGALRM );
   -- Current_Handler gives a callback to the handler
   Handler.all;
   Put_Line( "End testing SIGALRM handler..." );


   New_Line;
   Put_Line( "Testing SIGPWR handler..." );
   Handler := Current_Handler( SIGPWR );
   -- Current_Handler gives a callback to the handler
   Handler.all;
   Put_Line( "End testing SIGPWR handler..." );
   New_Line;

   Put_Line("Timer parameters");
   Put_Line("----------------");
   Put_Line("Time.sec = " & Timer.It_Value.Tv_Sec'Img );
   Put_Line("Time.usec= " & Timer.It_Value.Tv_Usec'Img );
   Put_Line("Preset.sec = " & Timer.It_Interval.Tv_Sec'Img );
   Put_Line("Preset.usec= " & Timer.It_Interval.Tv_Usec'Img );

   New_Line;
   Put("Arming timer...");

   Setitimer(I,ITIMER_REAL,Timer,OldTimer);
--                 ITimervalPtrs.To_Address(Timer'Unchecked_access),
--                 ITimervalPtrs.To_Address(OldTimer'Unchecked_Access));


   Put_Line("  Timer armed.");
   New_Line;

   Put_Line("I := " & I'Img);
   while (Counter <=  I) loop
      null;
--         Counter := Counter + 1;

--         delay(1.0);
      end loop;

end Timer_Test_B;

-- 
Tilman Gloetzner
ETAS Korea Ltd, Seoul, Korea