gcc/ada/a-elchha.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --    A D A . E X C E P T I O N S . L A S T _ C H A N C E _ H A N D L E R   --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --             Copyright (C) 2003 Free Software Foundation, Inc.            --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT. The copyright notice above, and the license provisions that follow --
  13 -- apply solely to the  contents of the part following the private keyword. --
  14 --                                                                          --
  15 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  16 -- terms of the  GNU General Public License as published  by the Free Soft- --
  17 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  18 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  19 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  20 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  21 -- for  more details.  You should have  received  a copy of the GNU General --
  22 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  23 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  24 -- MA 02111-1307, USA.                                                      --
  25 --                                                                          --
  26 -- As a special exception,  if other files  instantiate  generics from this --
  27 -- unit, or you link  this unit with other files  to produce an executable, --
  28 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  29 -- covered  by the  GNU  General  Public  License.  This exception does not --
  30 -- however invalidate  any other reasons why  the executable file  might be --
  31 -- covered by the  GNU Public License.                                      --
  32 --                                                                          --
  33 -- GNAT was originally developed  by the GNAT team at  New York University. --
  34 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  35 --                                                                          --
  36 ------------------------------------------------------------------------------
  37
  38 --  Default version for most targets
  39
  40 procedure Ada.Exceptions.Last_Chance_Handler
  41   (Except : Exception_Occurrence)
  42 is
  43    procedure Unhandled_Terminate;
  44    pragma No_Return (Unhandled_Terminate);
  45    pragma Import (C, Unhandled_Terminate, "__gnat_unhandled_terminate");
  46    --  Perform system dependent shutdown code
  47
  48    function Tailored_Exception_Information
  49      (X : Exception_Occurrence) return String;
  50    --  Exception information to be output in the case of automatic tracing
  51    --  requested through GNAT.Exception_Traces.
  52    --
  53    --  This is the same as Exception_Information if no backtrace decorator
  54    --  is currently in place. Otherwise, this is Exception_Information with
  55    --  the call chain raw addresses replaced by the result of a call to the
  56    --  current decorator provided with the call chain addresses.
  57
  58    pragma Import
  59      (Ada, Tailored_Exception_Information,
  60         "__gnat_tailored_exception_information");
  61
  62    procedure Tailored_Exception_Information
  63      (X    : Exception_Occurrence;
  64       Buff : in out String;
  65       Last : in out Integer);
  66    --  Procedural version of the above function. Instead of returning the
  67    --  result, this one is put in Buff (Buff'first .. Buff'first + Last)
  68
  69    procedure To_Stderr (S : String);
  70    pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
  71    --  Little routine to output string to stderr
  72
  73    Nline : constant String := String'(1 => ASCII.LF);
  74    --  Convenient shortcut
  75
  76    Msg : constant String := Except.Msg (1 .. Except.Msg_Length);
  77
  78    Max_Static_Exc_Info : constant := 1024;
  79    --  This should be enough for most exception information cases
  80    --  even though tailoring introduces some uncertainty.  The
  81    --  name+message should not exceed 320 chars, so that leaves at
  82    --  least 35 backtrace slots (each slot needs 19 chars for
  83    --  representing a 64 bit address).
  84
  85    subtype Exc_Info_Type is String (1 .. Max_Static_Exc_Info);
  86    type Str_Ptr is access Exc_Info_Type;
  87    Exc_Info : Str_Ptr;
  88    Exc_Info_Last : Natural := 0;
  89    --  Buffer that is allocated to store the tailored exception
  90    --  information while Adafinal is run. This buffer is allocated
  91    --  on the heap only when it is needed. It is better to allocate
  92    --  on the heap than on the stack since stack overflows are more
  93    --  common than heap overflows.
  94
  95    procedure Tailored_Exception_Information
  96      (X    : Exception_Occurrence;
  97       Buff : in out String;
  98       Last : in out Integer)
  99    is
 100       Info : constant String := Tailored_Exception_Information (X);
 101    begin
 102       Last := Info'Last;
 103       Buff (1 .. Last) := Info;
 104    end Tailored_Exception_Information;
 105
 106 begin
 107    --  First allocate & store the exception info in a buffer when
 108    --  we know it will be needed. This needs to be done before
 109    --  Adafinal because it implicitly uses the secondary stack.
 110
 111    if Except.Id.Full_Name.all (1) /= '_'
 112      and then Except.Num_Tracebacks /= 0
 113    then
 114       Exc_Info := new Exc_Info_Type;
 115       if Exc_Info /= null then
 116          Tailored_Exception_Information
 117            (Except, Exc_Info.all, Exc_Info_Last);
 118       end if;
 119    end if;
 120
 121    --  Let's shutdown the runtime now. The rest of the procedure
 122    --  needs to be careful not to use anything that would require
 123    --  runtime support. In particular, functions returning strings
 124    --  are banned since the sec stack is no longer functional.
 125    System.Standard_Library.Adafinal;
 126
 127    --  Check for special case of raising _ABORT_SIGNAL, which is not
 128    --  really an exception at all. We recognize this by the fact that
 129    --  it is the only exception whose name starts with underscore.
 130
 131    if Except.Id.Full_Name.all (1) = '_' then
 132       To_Stderr (Nline);
 133       To_Stderr ("Execution terminated by abort of environment task");
 134       To_Stderr (Nline);
 135
 136    --  If no tracebacks, we print the unhandled exception in the old style
 137    --  (i.e. the style used before ZCX was implemented). We do this to
 138    --  retain compatibility.
 139
 140    elsif Except.Num_Tracebacks = 0 then
 141       To_Stderr (Nline);
 142       To_Stderr ("raised ");
 143       To_Stderr (Except.Id.Full_Name.all (1 .. Except.Id.Name_Length - 1));
 144
 145       if Msg'Length /= 0 then
 146          To_Stderr (" : ");
 147          To_Stderr (Msg);
 148       end if;
 149
 150       To_Stderr (Nline);
 151
 152    --  Traceback exists
 153
 154    else
 155       --  Note we can have this whole information output twice if
 156       --  this occurrence gets reraised up to here.
 157
 158       To_Stderr (Nline);
 159       To_Stderr ("Execution terminated by unhandled exception");
 160       To_Stderr (Nline);
 161       To_Stderr (Exc_Info (1 .. Exc_Info_Last));
 162    end if;
 163
 164    Unhandled_Terminate;
 165 end Ada.Exceptions.Last_Chance_Handler;