gcc/ada/a-exextr.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                      ADA.EXCEPTIONS.EXCEPTION_TRACES                     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2007, Free Software Foundation, Inc.         --
  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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with Ada.Unchecked_Conversion;
  35
  36 pragma Warnings (Off);
  37 with Ada.Exceptions.Last_Chance_Handler;
  38 pragma Warnings (On);
  39 --  Bring last chance handler into closure
  40
  41 separate (Ada.Exceptions)
  42 package body Exception_Traces is
  43
  44    Nline : constant String := String'(1 => ASCII.LF);
  45    --  Convenient shortcut
  46
  47    type Exception_Action is access procedure (E : Exception_Occurrence);
  48    Global_Action : Exception_Action := null;
  49    pragma Export
  50      (Ada, Global_Action, "__gnat_exception_actions_global_action");
  51    --  Global action, executed whenever an exception is raised.  Changing the
  52    --  export name must be coordinated with code in g-excact.adb.
  53
  54    Raise_Hook_Initialized : Boolean := False;
  55    pragma Export
  56      (Ada, Raise_Hook_Initialized, "__gnat_exception_actions_initialized");
  57
  58    procedure Last_Chance_Handler
  59      (Except :  Exception_Occurrence);
  60    pragma Import (C, Last_Chance_Handler, "__gnat_last_chance_handler");
  61    pragma No_Return (Last_Chance_Handler);
  62    --  Users can replace the default version of this routine,
  63    --  Ada.Exceptions.Last_Chance_Handler.
  64
  65    function To_Action is new Ada.Unchecked_Conversion
  66      (Raise_Action, Exception_Action);
  67
  68    -----------------------
  69    -- Local Subprograms --
  70    -----------------------
  71
  72    procedure Notify_Exception (Excep : EOA; Is_Unhandled : Boolean);
  73    --  Factorizes the common processing for Notify_Handled_Exception and
  74    --  Notify_Unhandled_Exception. Is_Unhandled is set to True only in the
  75    --  latter case because Notify_Handled_Exception may be called for an
  76    --  actually unhandled occurrence in the Front-End-SJLJ case.
  77
  78    --------------------------------
  79    -- Import Run-Time C Routines --
  80    --------------------------------
  81
  82    --  The purpose of the following pragma Import is to ensure that we
  83    --  generate appropriate subprogram descriptors for all C routines in
  84    --  the standard GNAT library that can raise exceptions. This ensures
  85    --  that the exception propagation can properly find these routines
  86
  87    pragma Propagate_Exceptions;
  88
  89    ----------------------
  90    -- Notify_Exception --
  91    ----------------------
  92
  93    procedure Notify_Exception (Excep : EOA; Is_Unhandled : Boolean) is
  94    begin
  95       --  Output the exception information required by the Exception_Trace
  96       --  configuration. Take care not to output information about internal
  97       --  exceptions.
  98
  99       --  ??? In the Front-End ZCX case, the traceback entries we have at this
 100       --  point only include the ones we stored while walking up the stack *up
 101       --  to the handler*. All the frames above the subprogram in which the
 102       --  handler is found are missing.
 103
 104       if not Excep.Id.Not_Handled_By_Others
 105         and then
 106         (Exception_Trace = Every_Raise
 107           or else (Exception_Trace = Unhandled_Raise and then Is_Unhandled))
 108       then
 109          To_Stderr (Nline);
 110
 111          if Is_Unhandled then
 112             To_Stderr ("Unhandled ");
 113          end if;
 114
 115          To_Stderr ("Exception raised");
 116          To_Stderr (Nline);
 117          To_Stderr (Tailored_Exception_Information (Excep.all));
 118       end if;
 119
 120       --  Call the user-specific actions
 121       --  ??? We should presumably look at the reraise status here.
 122
 123       if Raise_Hook_Initialized
 124         and then Exception_Data_Ptr (Excep.Id).Raise_Hook /= null
 125       then
 126          To_Action (Exception_Data_Ptr (Excep.Id).Raise_Hook) (Excep.all);
 127       end if;
 128
 129       if Global_Action /= null then
 130          Global_Action (Excep.all);
 131       end if;
 132    end Notify_Exception;
 133
 134    ------------------------------
 135    -- Notify_Handled_Exception --
 136    ------------------------------
 137
 138    procedure Notify_Handled_Exception is
 139    begin
 140       Notify_Exception (Get_Current_Excep.all, Is_Unhandled => False);
 141    end Notify_Handled_Exception;
 142
 143    --------------------------------
 144    -- Notify_Unhandled_Exception --
 145    --------------------------------
 146
 147    procedure Notify_Unhandled_Exception is
 148       Excep : constant EOA := Get_Current_Excep.all;
 149
 150    begin
 151       --  Check whether there is any termination handler to be executed for
 152       --  the environment task, and execute it if needed. Here we handle both
 153       --  the Abnormal and Unhandled_Exception task termination. Normal
 154       --  task termination routine is executed elsewhere (either in the
 155       --  Task_Wrapper or in the Adafinal routine for the environment task).
 156
 157       Task_Termination_Handler.all (Excep.all);
 158
 159       Notify_Exception (Excep, Is_Unhandled => True);
 160       Debug_Unhandled_Exception (SSL.Exception_Data_Ptr (Excep.Id));
 161    end Notify_Unhandled_Exception;
 162
 163    -----------------------------------
 164    -- Unhandled_Exception_Terminate --
 165    -----------------------------------
 166
 167    procedure Unhandled_Exception_Terminate is
 168       Excep : constant EOA := Save_Occurrence (Get_Current_Excep.all.all);
 169       --  This occurrence will be used to display a message after finalization.
 170       --  It is necessary to save a copy here, or else the designated value
 171       --  could be overwritten if an exception is raised during finalization
 172       --  (even if that exception is caught).
 173
 174    begin
 175       Last_Chance_Handler (Excep.all);
 176    end Unhandled_Exception_Terminate;
 177
 178    ------------------------------------
 179    -- Handling GNAT.Exception_Traces --
 180    ------------------------------------
 181
 182    --  The bulk of exception traces output is centralized in Notify_Exception,
 183    --  for both the Handled and Unhandled cases. Extra task specific output is
 184    --  triggered in the task wrapper for unhandled occurrences in tasks. It is
 185    --  not performed in this unit to avoid dragging dependencies against the
 186    --  tasking units here.
 187
 188    --  We used to rely on the output performed by Unhanded_Exception_Terminate
 189    --  for the case of an unhandled occurrence in the environment thread, and
 190    --  the task wrapper was responsible for the whole output in the tasking
 191    --  case.
 192
 193    --  This initial scheme had a drawback: the output from Terminate only
 194    --  occurs after finalization is done, which means possibly never if some
 195    --  tasks keep hanging around.
 196
 197    --  The first "presumably obvious" fix consists in moving the Terminate
 198    --  output before the finalization. It has not been retained because it
 199    --  introduces annoying changes in output orders when the finalization
 200    --  itself issues outputs, this also in "regular" cases not resorting to
 201    --  Exception_Traces.
 202
 203    --  Today's solution has the advantage of simplicity and better isolates
 204    --  the Exception_Traces machinery.
 205
 206    --  It currently outputs the information about unhandled exceptions twice
 207    --  in the environment thread, once in the notification routine and once in
 208    --  the termination routine. Avoiding the second output is possible but so
 209    --  far has been considered undesirable. It would mean changing the order
 210    --  of outputs between the two runs with or without exception traces, while
 211    --  it seems preferable to only have additional outputs in the former
 212    --  case.
 213
 214 end Exception_Traces;