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