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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--             G N A T . T R A C E B A C K . S Y M B O L I C                --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--                     Copyright (C) 1999-2009, 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 2,  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.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT;  see file COPYING.  If not, write --

-- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --

-- Boston, MA 02110-1301, USA.                                              --

--                                                                          --

-- As a special exception,  if other files  instantiate  generics from this --

-- unit, or you link  this unit with other files  to produce an executable, --

-- this  unit  does not  by itself cause  the resulting  executable  to  be --

-- covered  by the  GNU  General  Public  License.  This exception does not --

-- however invalidate  any other reasons why  the executable file  might be --

-- covered by the  GNU Public License.                                      --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  Run-time symbolic traceback support

with System.Soft_Links;

with Ada.Exceptions.Traceback; use Ada.Exceptions.Traceback;

package body GNAT.Traceback.Symbolic is

   pragma Linker_Options ("-laddr2line");

   pragma Linker_Options ("-lbfd");

   pragma Linker_Options ("-liberty");

   package TSL renames System.Soft_Links;

   --  To perform the raw addresses to symbolic form translation we rely on a

   --  libaddr2line symbolizer which examines debug info from a provided

   --  executable file name, and an absolute path is needed to ensure the file

   --  is always found. This is "__gnat_locate_exec_on_path (gnat_argv [0])"

   --  for our executable file, a fairly heavy operation so we cache the

   --  result.

   Exename : System.Address;

   --  Pointer to the name of the executable file to be used on all

   --  invocations of the libaddr2line symbolization service.

   Exename_Resolved : Boolean := False;

   --  Flag to indicate whether we have performed the executable file name

   --  resolution already. Relying on a not null Exename for this purpose

   --  would be potentially inefficient as this is what we will get if the

   --  resolution attempt fails.

   ------------------------

   -- Symbolic_Traceback --

   ------------------------

   function Symbolic_Traceback (Traceback : Tracebacks_Array) return String is

      procedure convert_addresses

        (filename : System.Address;

         addrs    : System.Address;

         n_addrs  : Integer;

         buf      : System.Address;

         len      : System.Address);

      pragma Import (C, convert_addresses, "convert_addresses");

      --  This is the procedure version of the Ada-aware addr2line. It places

      --  in BUF a string representing the symbolic translation of the N_ADDRS

      --  raw addresses provided in ADDRS, looked up in debug information from

      --  FILENAME. LEN points to an integer which contains the size of the

      --  BUF buffer at input and the result length at output.

      --

      --  This procedure is provided by libaddr2line on targets that support

      --  it. A dummy version is in adaint.c for other targets so that build

      --  of shared libraries doesn't generate unresolved symbols.

      --

      --  Note that this procedure is *not* thread-safe.

      type Argv_Array is array (0 .. 0) of System.Address;

      gnat_argv : access Argv_Array;

      pragma Import (C, gnat_argv, "gnat_argv");

      function locate_exec_on_path

        (c_exename : System.Address) return System.Address;

      pragma Import (C, locate_exec_on_path, "__gnat_locate_exec_on_path");

      Res : String (1 .. 256 * Traceback'Length);

      Len : Integer;

      use type System.Address;

   begin

      --  The symbolic translation of an empty set of addresses is an empty

      --  string.

      if Traceback'Length = 0 then

         return "";

      end if;

      --  If our input set of raw addresses is not empty, resort to the

      --  libaddr2line service to symbolize it all.

      --  Compute, cache and provide the absolute path to our executable file

      --  name as the binary file where the relevant debug information is to be

      --  found. If the executable file name resolution fails, we have no

      --  sensible basis to invoke the symbolizer at all.

      --  Protect all this against concurrent accesses explicitly, as the

      --  underlying services are potentially thread unsafe.

      TSL.Lock_Task.all;

      if not Exename_Resolved then

         Exename := locate_exec_on_path (gnat_argv (0));

         Exename_Resolved := True;

      end if;

      if Exename /= System.Null_Address then

         Len := Res'Length;

         convert_addresses

           (Exename, Traceback'Address, Traceback'Length,

            Res (1)'Address, Len'Address);

      end if;

      TSL.Unlock_Task.all;

      --  Return what the addr2line symbolizer has produced if we have called

      --  it (the executable name resolution succeeded), or an empty string

      --  otherwise.

      if Exename /= System.Null_Address then

         return Res (1 .. Len);

      else

         return "";

      end if;

   end Symbolic_Traceback;

   function Symbolic_Traceback (E : Exception_Occurrence) return String is

   begin

      return Symbolic_Traceback (Tracebacks (E));

   end Symbolic_Traceback;

end GNAT.Traceback.Symbolic;