------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                       G N A T . T R A C E B A C K                        --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                     Copyright (C) 1999-2020, AdaCore                     --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  Run-time non-symbolic traceback support

--  This package provides a method for generating a traceback of the
--  current execution location. The traceback shows the locations of
--  calls in the call chain, up to either the top or a designated
--  number of levels.

--  The traceback information is in the form of absolute code locations.
--  These code locations may be converted to corresponding source locations
--  using the external addr2line utility, or from within GDB.

--  In order to use this facility, in some cases the binder must be invoked
--  with -E switch (store the backtrace with exception occurrence). Please
--  refer to gnatbind documentation for more information.

--  To analyze the code locations later using addr2line or gdb, the necessary
--  units must be compiled with the debugging switch -g in the usual manner.
--  Note that it is not necessary to compile with -g to use Call_Chain. In
--  other words, the following sequence of steps can be used:

--     Compile without -g
--     Run the program, and call Call_Chain
--     Recompile with -g
--     Use addr2line to interpret the absolute call locations (note that
--      addr2line expects addresses in hexadecimal format).

--  This capability is currently supported on the following targets:

--     AiX PowerPC
--     GNU/Linux x86
--     GNU/Linux PowerPC
--     LynxOS x86
--     LynxOS 178 xcoff PowerPC
--     LynxOS 178 elf PowerPC
--     Solaris x86
--     Solaris sparc
--     VxWorks ARM
--     VxWorks7 ARM
--     VxWorks PowerPC
--     VxWorks x86
--     Windows XP

--  Note: see also GNAT.Traceback.Symbolic, a child unit in file g-trasym.ads
--  providing symbolic trace back capability for a subset of the above targets.

with System;
with Ada.Exceptions.Traceback;

package GNAT.Traceback is
   pragma Elaborate_Body;

   subtype Code_Loc is System.Address;
   --  Code location used in building tracebacks

   subtype Tracebacks_Array is Ada.Exceptions.Traceback.Tracebacks_Array;
   --  Traceback array used to hold a generated traceback list

   ----------------
   -- Call_Chain --
   ----------------

   procedure Call_Chain (Traceback : out Tracebacks_Array; Len : out Natural);
   --  Store up to Traceback'Length tracebacks corresponding to the current
   --  call chain. The first entry stored corresponds to the deepest level
   --  of subprogram calls. Len shows the number of traceback entries stored.
   --  It will be equal to Traceback'Length unless the entire traceback is
   --  shorter, in which case positions in Traceback past the Len position
   --  are undefined on return.

   function Call_Chain
     (Max_Len     : Positive;
      Skip_Frames : Natural := 1) return Tracebacks_Array;
   --  Returns up to Max_Len tracebacks corresponding to the current call
   --  chain. Result array order is the same as in above procedure Call_Chain
   --  except that Skip_Frames says how many of the most recent calls should be
   --  excluded from the result, starting with this procedure itself: 1 means
   --  exclude the frame for this procedure, 2 means 1 + exclude the frame for
   --  this procedure's caller, ...

end GNAT.Traceback;
