Ada with Protected Object & Importing C program in Linux

Ada with Protected Object & Importing C program in Linux

[Lin]

I've a problem of binding an Ada program(with protected objects) with
C programs in Linux. Any clue is helpful to me. Thanks.

The working environment is Slackware Linux,Gnat3.13p
My problem: In Linux, the program with protected object can work fine
without importing a C program; the program will raise "Segmentation
fault when it  imports a C program. The same program works fine in
WinNT. The code is shown below, which is to asks the protected object
for an new request id.
  
---------------------
---Ada programs--
---------------------
with my_test;
with Ada.Text_IO;use Ada.Tex_IO;
procedure my_main is
   my_id : my_test.Request_Id_Type := 0;
begin
   Put_Line ("Hello World!!");
   for i in 1 .. 10 loop
     my_test.Allocate_New_Id (my_id);
     my_test.Calling_C;
     Put_Line (
      "Request id=" & my_test.Request_Id_Type'Image (my_id));
   end loop;
end my_main;
------------
package my_test is
   type Request_Id_Type is mod 2 ** 16;
   procedure Allocate_New_Id (Id : out Request_Id_Type);
   procedure Calling_C;
   pragma Import (C, Calling_C);
   pragma Import_Procedure (Calling_C, "Calling_C");
end my_test;
------------
package body my_test is
   type Is_Used_Array is array (Request_Id_Type) of Boolean;
   protected type Request_Id_Server_Type is
      entry Get (Id : out Request_Id_Type);
      procedure Free (Id : in Request_Id_Type);
   private
      Latest : Request_Id_Type := Request_Id_Type'First;
      Is_Used : Is_Used_Array := (others => False);
      Count       : Request_Id_Type := 0;
   end Request_Id_Server_Type;

   protected body Request_Id_Server_Type
   is
      procedure Free (Id : in Request_Id_Type)
      is
      begin
         if Is_Used (Id) then
            Is_Used (Id) := False;
            Count := Count - 1;
         end if;
      end Free;

      entry Get (Id : out Request_Id_Type)
         when Count < Request_Id_Type'Last is
      begin
         while Is_Used (Latest)
         loop
            Latest := Latest + 1;
         end loop;
         Id := Latest;
         Is_Used (Id) := True;
         Count := Count + 1;
         Latest := Latest + 1;
      end Get;
   end Request_Id_Server_Type;
   type Access_Request_Id_Server_Type is access
Request_Id_Server_Type;
   Request_Id_Server : Access_Request_Id_Server_Type :=
                                            new
Request_Id_Server_Type;
   procedure Allocate_New_Id (Id : out Request_Id_Type)
   is
   begin
      Request_Id_Server.Get (Id);
   end Allocate_New_Id;
end my_test;
---------------------
---the C program---
---------------------
#include <stdio.h>
 Calling_C(){
   printf ("\nC is Called now");
 }       
----------------------

Re: Ada with Protected Object & Importing C program in Linux

[James Rogers]

Lin wrote:
> 
> I've a problem of binding an Ada program(with protected objects) with
> C programs in Linux. Any clue is helpful to me. Thanks.
> 
> The working environment is Slackware Linux,Gnat3.13p
> My problem: In Linux, the program with protected object can work fine
> without importing a C program; the program will raise "Segmentation
> fault when it  imports a C program. The same program works fine in
> WinNT. The code is shown below, which is to asks the protected object
> for an new request id.
> 
> ---------------------
> ---Ada programs--
> ---------------------
> with my_test;
> with Ada.Text_IO;use Ada.Tex_IO;
> procedure my_main is
>    my_id : my_test.Request_Id_Type := 0;
> begin
>    Put_Line ("Hello World!!");
>    for i in 1 .. 10 loop
>      my_test.Allocate_New_Id (my_id);
>      my_test.Calling_C;
>      Put_Line (
>       "Request id=" & my_test.Request_Id_Type'Image (my_id));
>    end loop;
> end my_main;
> ------------
> package my_test is
>    type Request_Id_Type is mod 2 ** 16;
>    procedure Allocate_New_Id (Id : out Request_Id_Type);
>    procedure Calling_C;
>    pragma Import (C, Calling_C);
>    pragma Import_Procedure (Calling_C, "Calling_C");
> end my_test;
> ------------
> package body my_test is
>    type Is_Used_Array is array (Request_Id_Type) of Boolean;
>    protected type Request_Id_Server_Type is
>       entry Get (Id : out Request_Id_Type);
>       procedure Free (Id : in Request_Id_Type);
>    private
>       Latest : Request_Id_Type := Request_Id_Type'First;
>       Is_Used : Is_Used_Array := (others => False);
>       Count       : Request_Id_Type := 0;
>    end Request_Id_Server_Type;
> 
>    protected body Request_Id_Server_Type
>    is
>       procedure Free (Id : in Request_Id_Type)
>       is
>       begin
>          if Is_Used (Id) then
>             Is_Used (Id) := False;
>             Count := Count - 1;
>          end if;
>       end Free;
> 
>       entry Get (Id : out Request_Id_Type)
>          when Count < Request_Id_Type'Last is
>       begin
>          while Is_Used (Latest)
>          loop
>             Latest := Latest + 1;
>          end loop;
>          Id := Latest;
>          Is_Used (Id) := True;
>          Count := Count + 1;
>          Latest := Latest + 1;
>       end Get;
>    end Request_Id_Server_Type;
>    type Access_Request_Id_Server_Type is access
> Request_Id_Server_Type;
>    Request_Id_Server : Access_Request_Id_Server_Type :=
>                                             new
> Request_Id_Server_Type;
>    procedure Allocate_New_Id (Id : out Request_Id_Type)
>    is
>    begin
>       Request_Id_Server.Get (Id);
>    end Allocate_New_Id;
> end my_test;
> ---------------------
> ---the C program---
> ---------------------
> #include <stdio.h>
>  Calling_C(){
>    printf ("\nC is Called now");
>  }
> ----------------------

This C function does not match the signature of the procedure
"Calling_C". The function Calling_C does not return void. A C
program will return "int" unless you specify otherwise. Either
the C function or the Ada procedure must be modified so that they
both agree.

Jim Rogers
Colorado Springs, Colorado USA

Re: Ada with Protected Object & Importing C program in Linux

[Lin]

Thanks for the advice. But after adding "void" before the C routine,
it still raise "segmentation error".
---------------------
---the C program---
---------------------
#include <stdio.h>
  Calling_C(){
   printf ("\nC is Called now");
  }
----------------------

Re: Ada with Protected Object & Importing C program in Linux

[Lin]

After I get rid of the Java shared library from the compile command,
the program works fine.

Actually, I need to use Ada to create JVM via a C program in Linux,
and the Ada program includes a protected object to update data as
well. That is, the compile command needs to include Java shared
library(-ljvm, -lhpi, -ljava). Without the protected object, Ada can
create JVM successfully,but when adding the protected object, it
raises the "segmentation fault". It seems that the protected object in
Ada is not compatible with Java shared library.

Anybody has ever used the combination of Ada protected object and Java
shared library?

Many Thanks,
Linda