gcc/ada/g-exctra.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                  G N A T . E X C E P T I O N _ T R A C E S               --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.6 $
  10 --                                                                          --
  11 --            Copyright (C) 2000-2001 Ada Core Technologies, Inc.           --
  12 --                                                                          --
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  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
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  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
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  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com).   --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with System.Standard_Library; use System.Standard_Library;
  36 with System.Soft_Links;       use System.Soft_Links;
  37
  38 package body GNAT.Exception_Traces is
  39
  40    --  Calling the decorator directly from where it is needed would require
  41    --  introducing nasty dependencies upon the spec of this package (typically
  42    --  in a-except.adb). We also have to deal with the fact that the traceback
  43    --  array within an exception occurrence and the one the decorator shall
  44    --  accept are of different types. These are two reasons for which a wrapper
  45    --  with a System.Address argument is indeed used to call the decorator
  46    --  provided by the user of this package. This wrapper is called via a
  47    --  soft-link, which either is null when no decorator is in place or "points
  48    --  to" the following function otherwise.
  49
  50    function Decorator_Wrapper
  51      (Traceback : System.Address;
  52       Len       : Natural)
  53       return      String;
  54    --  The wrapper to be called when a decorator is in place for exception
  55    --  backtraces.
  56    --
  57    --  Traceback is the address of the call chain array as stored in the
  58    --  exception occurrence and Len is the number of significant addresses
  59    --  contained in this array.
  60
  61    Current_Decorator : Traceback_Decorator := null;
  62    --  The decorator to be called by the wrapper when it is not null, as set
  63    --  by Set_Trace_Decorator. When this access is null, the wrapper is null
  64    --  also and shall then not be called.
  65
  66    -----------------------
  67    -- Decorator_Wrapper --
  68    -----------------------
  69
  70    function Decorator_Wrapper
  71      (Traceback : System.Address;
  72       Len       : Natural)
  73       return      String
  74    is
  75       Decorator_Traceback : Tracebacks_Array (1 .. Len);
  76       for Decorator_Traceback'Address use Traceback;
  77
  78       --  Handle the "transition" from the array stored in the exception
  79       --  occurrence to the array expected by the decorator.
  80
  81       pragma Import (Ada, Decorator_Traceback);
  82
  83    begin
  84       return Current_Decorator.all (Decorator_Traceback);
  85    end Decorator_Wrapper;
  86
  87    -------------------------
  88    -- Set_Trace_Decorator --
  89    -------------------------
  90
  91    procedure Set_Trace_Decorator (Decorator : Traceback_Decorator) is
  92    begin
  93       Current_Decorator := Decorator;
  94
  95       if Current_Decorator /= null then
  96          Traceback_Decorator_Wrapper := Decorator_Wrapper'Access;
  97       else
  98          Traceback_Decorator_Wrapper := null;
  99       end if;
 100    end Set_Trace_Decorator;
 101
 102    --  Trace_On/Trace_Off control the kind of automatic output to occur
 103    --  by way of the global Exception_Trace variable.
 104
 105    ---------------
 106    -- Trace_Off --
 107    ---------------
 108
 109    procedure Trace_Off is
 110    begin
 111       Exception_Trace := RM_Convention;
 112    end Trace_Off;
 113
 114    --------------
 115    -- Trace_On --
 116    --------------
 117
 118    procedure Trace_On (Kind : in Trace_Kind) is
 119    begin
 120       case Kind is
 121          when Every_Raise =>
 122             Exception_Trace := Every_Raise;
 123          when Unhandled_Raise =>
 124             Exception_Trace := Unhandled_Raise;
 125       end case;
 126    end Trace_On;
 127
 128 end GNAT.Exception_Traces;