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-- CB20005.A

--

--                             Grant of Unlimited Rights

--

--     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 exceptions are raised and properly handled locally in

--      protected operations.

--

-- TEST DESCRIPTION:

--      Declare a package with a protected type, including protected operation

--      declarations and private data, simulating a counting semaphore.

--      In the main procedure, perform calls on protected operations

--      of the protected object designed to induce the raising of exceptions.

--

--      Ensure that the exceptions are raised and handled locally in a

--      protected procedures and functions, and that in this case the

--      exceptions will not propagate to the calling unit.  Use specific

--      exception handlers in the protected functions.

--

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--

--!

package CB20005_0 is               -- Package Semaphore.

   Handled_In_Function,

   Handled_In_Procedure : Boolean := False;

   Resource_Overflow,

   Resource_Underflow   : exception;

   protected type Counting_Semaphore (Max_Resources : Integer) is

      procedure Secure;

      function  Resource_Limit_Exceeded return Boolean;

      procedure Release;

   private

      Count : Integer := Max_Resources;

   end Counting_Semaphore;

end CB20005_0;

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

with Report;

package body CB20005_0 is               -- Package Semaphore.

   protected body Counting_Semaphore is

      procedure Secure is

      begin

         if (Count = 0) then               -- No resources left to secure.

            raise Resource_Underflow;

            Report.Failed

              ("Program control not transferred by raise in Secure");

         else

            Count := Count - 1;             -- Avail resources decremented.

         end if;

      exception

         when Resource_Underflow =>         -- Exception handled locally in

            Handled_In_Procedure := True;   -- this protected operation.

         when others =>

            Report.Failed ("Unexpected exception raised in Secure");

      end Secure;

      function Resource_Limit_Exceeded return Boolean is

      begin

         if (Count > Max_Resources) then

            raise Resource_Overflow;       -- Exception used as control flow

                                           -- mechanism.

            Report.Failed

              ("Program control not transferred by raise in " &

               "Resource_Limit_Exceeded");

         else

            return (False);

         end if;

      exception

         when Resource_Overflow =>         -- Handle its own raised

            Handled_In_Function := True;   -- exception.

            return (True);

         when others =>

            Report.Failed

              ("Unexpected exception raised in Resource_Limit_Exceeded");

      end Resource_Limit_Exceeded;

      procedure Release is

      begin

         Count := Count + 1;               -- Count of resources available

                                           -- incremented.

         if Resource_Limit_Exceeded then   -- Call to protected operation

            Count := Count - 1;            -- function that raises/handles

         end if;                           -- an exception.

      exception

         when Resource_Overflow =>

            Handled_In_Function := False;

            Report.Failed ("Exception propagated to Function Release");

         when others =>

            Report.Failed ("Unexpected exception raised in Function Release");

      end Release;

   end Counting_Semaphore;

end CB20005_0;

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

with CB20005_0;                           -- Package Semaphore.

with Report;

procedure CB20005 is

begin

   Report.Test ("CB20005", "Check that exceptions are raised and handled " &

                           "correctly in protected operations" );

   Test_Block:

   declare

      package Semaphore renames CB20005_0;

      Total_Resources_Available : constant := 1;

      Resources : Semaphore.Counting_Semaphore(Total_Resources_Available);

                                          -- An object of protected type.

   begin

      Allocate_Resources:

      declare

         Loop_Count : Integer := Total_Resources_Available + 1;

      begin

         for I in 1..Loop_Count loop -- Force exception.

            Resources.Secure;

         end loop;

      exception

         when Semaphore.Resource_Underflow =>

            Semaphore.Handled_In_Procedure := False; -- Excptn not handled

            Report.Failed                            -- in prot. operation.

              ("Resource_Underflow exception not handled " &

               "in Allocate_Resources");

         when others =>

            Report.Failed

              ("Exception unexpectedly raised during resource allocation");

      end Allocate_Resources;

      Deallocate_Resources:

      declare

         Loop_Count : Integer := Total_Resources_Available + 1;

      begin

         for I in 1..Loop_Count loop -- Force excptn.

            Resources.Release;

         end loop;

      exception

         when Semaphore.Resource_Overflow =>

            Semaphore.Handled_In_Function := False; -- Exception not handled

               Report.Failed                        -- in prot. operation.

                 ("Resource overflow not handled by function");

            when others =>

               Report.Failed

                 ("Exception raised during resource deallocation");

      end Deallocate_Resources;

      if not (Semaphore.Handled_In_Procedure and -- Incorrect excpt. handling

              Semaphore.Handled_In_Function)     -- in protected operations.

      then

         Report.Failed

           ("Improper exception handling by protected operations");

      end if;

   exception

      when others =>

         Report.Failed ("Exception raised and propagated in test");

   end Test_Block;

   Report.Result;

end CB20005;