c974005.a

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-- C974005.A
--
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--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
--     unlimited rights in the software and documentation contained herein.
--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making 
--     this public release, the Government intends to confer upon all 
--     recipients unlimited rights  equal to those held by the Government.  
--     These rights include rights to use, duplicate, release or disclose the 
--     released technical data and computer software in whole or in part, in 
--     any manner and for any purpose whatsoever, and to have or permit others 
--     to do so.
--
--                                    DISCLAIMER
--
--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 
--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE 
--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
--     PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- OBJECTIVE:
--      Check that Tasking_Error is raised at the point of an entry call
--      which is the triggering statement of an asynchronous select, if
--      the entry call is queued, but the task containing the entry completes
--      before it can be accepted or canceled.
--
--      Check that the abortable part is aborted if it does not complete
--      before the triggering statement completes.
--
--      Check that the sequence of statements of the triggering alternative
--      is not executed.
--
-- TEST DESCRIPTION:
--      Declare a main procedure containing an asynchronous select with a task
--      entry call as triggering statement. Force the entry call to be
--      queued by having the task call a procedure, prior to the corresponding
--      accept statement, which simulates a routine waiting for user input
--      (with a delay). 
--
--      Simulate a time-consuming routine in the abortable part by calling a
--      procedure containing an infinite loop. Meanwhile, simulate input by
--      the user (the delay expires) which is NOT the input expected by the
--      guard on the accept statement. The entry remains closed, and the
--      task completes its execution. Since the entry was not accepted before
--      its task completed, Tasking_Error is raised at the point of the entry
--      call.
--
--
-- CHANGE HISTORY:
--      06 Dec 94   SAIC    ACVC 2.0
--
--!

package C974005_0 is  -- Automated teller machine abstraction.


   -- Flags for testing purposes:

   Count : Integer := 1234;            

   type Key_Enum is (None, Cancel, Deposit, Withdraw);

   type Card_Number_Type is private;
   type Card_PIN_Type    is private;
   type ATM_Card_Type    is private;


   Transaction_Canceled : exception;


   task type ATM_Keyboard_Task is
      entry Cancel_Pressed;
   end ATM_Keyboard_Task;


   procedure Read_Card (Card : in out ATM_Card_Type);

   procedure Validate_Card (Card : in ATM_Card_Type);

   procedure Perform_Transaction (Card : in ATM_Card_Type);

private

   type Card_Number_Type is range   1 .. 9999;
   type Card_PIN_Type    is range 100 ..  999;

   type ATM_Card_Type is record
      Number : Card_Number_Type;
      PIN    : Card_PIN_Type;
   end record;

end C974005_0;


     --==================================================================--


with Report;
with ImpDef;

package body C974005_0 is


   procedure Listen_For_Input (Key : out Key_Enum) is
   begin
      -- Simulate the situation where a user waits a bit for the card to
      -- be validated, then presses a transaction key (NOT Cancel).

      -- Delay long enough to force queuing of Keyboard.Cancel_Pressed.
      delay ImpDef.Clear_Ready_Queue;

      if Report.Equal (3, 3) then  -- Always true.
         Key := Deposit;           -- Cancel is NOT pressed.
      end if;
   end Listen_For_Input;


   task body ATM_Keyboard_Task is
      Key_Pressed : Key_Enum := None;
   begin

      -- Note: no loop. If the user does not press Cancel, the task completes.
      -- In this model of the keyboard monitor, the user only gets one chance
      -- to cancel the card validation.
                                                            -- Force entry
         Listen_For_Input (Key_Pressed);                    -- calls to be
                                                            -- queued, but do
                                                            -- NOT set guard
                                                            -- to true.
      select
         when (Key_Pressed = Cancel) =>                     -- Guard is false,
            accept Cancel_Pressed do                        -- so entry call
               Report.Failed ("Accept statement executed"); -- remains queued.
            end Cancel_Pressed;
      else                                                  -- Else alternative
         Key_Pressed := None;                               -- executed, then
      end select;                                           -- task ends.
   exception
      when others => 
         Report.Failed ("Unexpected exception in ATM_Keyboard_Task"); 
   end ATM_Keyboard_Task;



   procedure Read_Card (Card : in out ATM_Card_Type) is
   begin
      Card.Number := 9999;
      Card.PIN    := 111;
   end Read_Card;


   procedure Validate_Card (Card : in ATM_Card_Type) is
   begin
      -- Simulate an exceedingly long validation activity.
      loop                                             -- Infinite loop.
         Count := (Count + 1) mod Integer (Card.PIN);

         -- Synch Point to allow transfer of control to Keyboard task
         -- during this simulation
         delay ImpDef.Minimum_Task_Switch;

         exit when not Report.Equal (Count, Count);    -- Always false.
      end loop;
   end Validate_Card;


   procedure Perform_Transaction (Card : in ATM_Card_Type) is
   begin
      Report.Failed ("Exception not re-raised immediately following " &
                     "asynchronous select");
      if Count = 1234 then
         -- Additional analysis added to aid developers
         Report.Failed ("Abortable part did not execute");
      end if;
   end Perform_Transaction;


end C974005_0;


     --==================================================================--


with Report;

with C974005_0;  -- Automated teller machine abstraction.
use  C974005_0;

procedure C974005 is

   Card_Data : ATM_Card_Type;

begin  -- Main program.

   Report.Test ("C974005", "ATC: trigger is queued but task terminates" &
                             " before call is serviced");

   Read_Card (Card_Data);

   begin

      declare
         Keyboard : C974005_0.ATM_Keyboard_Task;
      begin

         --                                    --
         -- Asynchronous select is tested here --
         --                                    --

         select
            Keyboard.Cancel_Pressed;      -- Entry call initially queued, so
                                          -- abortable part starts.

                                          -- Tasking_Error raised here when
                                          -- Keyboard completes before entry
                                          -- call can be accepted, and before
                                          -- abortable part completes.

            raise Transaction_Canceled;   -- Should not be executed.
         then abort
            Validate_Card (Card_Data);    -- Keyboard task completes before
                                          -- Keyboard.Cancel_Pressed is
                                          -- accepted, and before this call
                                          -- finishes. Tasking_Error is raised
                                          -- at the point of the entry call,
                                          -- and this call is aborted.
            -- Check that the whole of the abortable part is aborted, not just
            -- the statement in the abortable part that was executing at
            -- the time
            Report.Failed ("Abortable part not aborted");
         end select;
         Perform_Transaction (Card_Data); -- Should not be reached.
      exception
         when Transaction_Canceled =>
            Report.Failed ("Triggering alternative sequence of statements " &
                           "executed");
         when Tasking_Error        =>
            if Count = 1234 then
               Report.Failed ("Abortable part did not execute");
            end if;
         when others       =>
            Report.Failed ("Wrong exception raised");
      end;

   exception
      when Tasking_Error        =>
         Report.Failed ("Correct exception raised at wrong level");
      when others       =>
         Report.Failed ("Wrong exception raised at wrong level");
   end;

   Report.Result;

end C974005;