cb20007.a

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-- CB20007.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 can be directly propagated to
--      the calling unit by 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.
--
--      The exceptions raised are to be propagated directly from the protected
--      operations to the calling unit. 
--
--      Ensure that the exceptions are raised and correctly propagated directly
--      to the calling unit from protected procedures and functions.
--
--       
-- CHANGE HISTORY:
--      06 Dec 94   SAIC    ACVC 2.0
--
--!

package CB20007_0 is               -- Package Semaphore.

   Handled_In_Function_Caller,
   Handled_In_Procedure_Caller : 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 CB20007_0;

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

with Report;

package body CB20007_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");
         else
            Count := Count - 1;            -- Available resources decremented.
         end if;                          
         -- No exception handlers here, direct propagation to calling unit.
      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");
         else                              
            return (False);
         end if;
         -- No exception handlers here, direct propagation to calling unit.
      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 an
                                           -- exception.
            Report.Failed("Resource limit exceeded");
         end if;                           
         -- No exception handler here for exception raised in function.
         -- Exception will propagate directly to calling unit.
      end Release;


   end Counting_Semaphore;

end CB20007_0;


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


with CB20007_0;                           -- Package Semaphore.
with Report;

procedure CB20007 is
begin

   Test_Block:
   declare

      package Semaphore renames CB20007_0;

      Total_Resources_Available : constant := 1;

      Resources : Semaphore.Counting_Semaphore (Total_Resources_Available);
                                             -- An object of protected type.

   begin

      Report.Test ("CB20007", "Check that exceptions are raised and can "   &
                              "be directly propagated to the calling unit " &
                              "by protected operations" );

      Allocate_Resources:
      declare
         Loop_Count : Integer := Total_Resources_Available + 1;
      begin                                   -- Force exception.
         for I in 1..Loop_Count loop  
            Resources.Secure;
         end loop;
         Report.Failed ("Exception not propagated from protected " &
                        " operation in Allocate_Resources");
      exception                                     
         when Semaphore.Resource_Underflow =>              -- Exception prop.
            Semaphore.Handled_In_Procedure_Caller := True; -- from protected
                                                           -- procedure.
         when others =>
            Report.Failed ("Unknown exception during resource allocation");
      end Allocate_Resources;

   
      Deallocate_Resources:
      declare
         Loop_Count : Integer := Total_Resources_Available + 1;
      begin                                   -- Force exception.
         for I in 1..Loop_Count loop  
            Resources.Release;  
         end loop;
         Report.Failed ("Exception not propagated from protected " &
                        "operation in Deallocate_Resources");
      exception                                     
         when Semaphore.Resource_Overflow =>              -- Exception prop
            Semaphore.Handled_In_Function_Caller := True; -- from protected
                                                          -- function.
         when others =>
            Report.Failed ("Exception raised during resource deallocation");
      end Deallocate_Resources;


      if not (Semaphore.Handled_In_Procedure_Caller and -- Incorrect exception
              Semaphore.Handled_In_Function_Caller)     -- handling in
      then                                              -- protected ops.
          Report.Failed                                 
            ("Improper exception propagation by protected operations");
      end if;

   exception

      when others =>
         Report.Failed ("Unexpected exception " &
                        " raised and propagated in test");
   end Test_Block;


   Report.Result;

end CB20007;