gcc/ada/g-trasym.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --             G N A T . T R A C E B A C K . S Y M B O L I C                --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 1999-2010, AdaCore                     --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  Run-time symbolic traceback support
  33
  34 with System.Soft_Links;
  35 with Ada.Exceptions.Traceback; use Ada.Exceptions.Traceback;
  36
  37 package body GNAT.Traceback.Symbolic is
  38
  39    pragma Linker_Options ("-laddr2line");
  40    pragma Linker_Options ("-lbfd");
  41    pragma Linker_Options ("-liberty");
  42
  43    package TSL renames System.Soft_Links;
  44
  45    --  To perform the raw addresses to symbolic form translation we rely on a
  46    --  libaddr2line symbolizer which examines debug info from a provided
  47    --  executable file name, and an absolute path is needed to ensure the file
  48    --  is always found. This is "__gnat_locate_exec_on_path (gnat_argv [0])"
  49    --  for our executable file, a fairly heavy operation so we cache the
  50    --  result.
  51
  52    Exename : System.Address;
  53    --  Pointer to the name of the executable file to be used on all
  54    --  invocations of the libaddr2line symbolization service.
  55
  56    Exename_Resolved : Boolean := False;
  57    --  Flag to indicate whether we have performed the executable file name
  58    --  resolution already. Relying on a not null Exename for this purpose
  59    --  would be potentially inefficient as this is what we will get if the
  60    --  resolution attempt fails.
  61
  62    ------------------------
  63    -- Symbolic_Traceback --
  64    ------------------------
  65
  66    function Symbolic_Traceback (Traceback : Tracebacks_Array) return String is
  67
  68       procedure convert_addresses
  69         (filename : System.Address;
  70          addrs    : System.Address;
  71          n_addrs  : Integer;
  72          buf      : System.Address;
  73          len      : System.Address);
  74       pragma Import (C, convert_addresses, "convert_addresses");
  75       --  This is the procedure version of the Ada-aware addr2line. It places
  76       --  in BUF a string representing the symbolic translation of the N_ADDRS
  77       --  raw addresses provided in ADDRS, looked up in debug information from
  78       --  FILENAME. LEN points to an integer which contains the size of the
  79       --  BUF buffer at input and the result length at output.
  80       --
  81       --  This procedure is provided by libaddr2line on targets that support
  82       --  it. A dummy version is in adaint.c for other targets so that build
  83       --  of shared libraries doesn't generate unresolved symbols.
  84       --
  85       --  Note that this procedure is *not* thread-safe.
  86
  87       type Argv_Array is array (0 .. 0) of System.Address;
  88       gnat_argv : access Argv_Array;
  89       pragma Import (C, gnat_argv, "gnat_argv");
  90
  91       function locate_exec_on_path
  92         (c_exename : System.Address) return System.Address;
  93       pragma Import (C, locate_exec_on_path, "__gnat_locate_exec_on_path");
  94
  95       Res : String (1 .. 256 * Traceback'Length);
  96       Len : Integer;
  97
  98       use type System.Address;
  99
 100    begin
 101       --  The symbolic translation of an empty set of addresses is an empty
 102       --  string.
 103
 104       if Traceback'Length = 0 then
 105          return "";
 106       end if;
 107
 108       --  If our input set of raw addresses is not empty, resort to the
 109       --  libaddr2line service to symbolize it all.
 110
 111       --  Compute, cache and provide the absolute path to our executable file
 112       --  name as the binary file where the relevant debug information is to be
 113       --  found. If the executable file name resolution fails, we have no
 114       --  sensible basis to invoke the symbolizer at all.
 115
 116       --  Protect all this against concurrent accesses explicitly, as the
 117       --  underlying services are potentially thread unsafe.
 118
 119       TSL.Lock_Task.all;
 120
 121       if not Exename_Resolved then
 122          Exename := locate_exec_on_path (gnat_argv (0));
 123          Exename_Resolved := True;
 124       end if;
 125
 126       if Exename /= System.Null_Address then
 127          Len := Res'Length;
 128          convert_addresses
 129            (Exename, Traceback'Address, Traceback'Length,
 130             Res (1)'Address, Len'Address);
 131       end if;
 132
 133       TSL.Unlock_Task.all;
 134
 135       --  Return what the addr2line symbolizer has produced if we have called
 136       --  it (the executable name resolution succeeded), or an empty string
 137       --  otherwise.
 138
 139       if Exename /= System.Null_Address then
 140          return Res (1 .. Len);
 141       else
 142          return "";
 143       end if;
 144
 145    end Symbolic_Traceback;
 146
 147    function Symbolic_Traceback (E : Exception_Occurrence) return String is
 148    begin
 149       return Symbolic_Traceback (Tracebacks (E));
 150    end Symbolic_Traceback;
 151
 152 end GNAT.Traceback.Symbolic;