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) 2003-2019, 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 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--  Default version for most targets
33
34pragma Compiler_Unit_Warning;
35
36with System.Standard_Library; use System.Standard_Library;
37with System.Soft_Links; use System;
38
39procedure Ada.Exceptions.Last_Chance_Handler
40  (Except : Exception_Occurrence)
41is
42   procedure Unhandled_Terminate;
43   pragma No_Return (Unhandled_Terminate);
44   pragma Import (C, Unhandled_Terminate, "__gnat_unhandled_terminate");
45   --  Perform system dependent shutdown code
46
47   function Exception_Message_Length
48     (X : Exception_Occurrence) return Natural;
49   pragma Import (Ada, Exception_Message_Length, "__gnat_exception_msg_len");
50
51   procedure Append_Info_Exception_Message
52     (X    : Exception_Occurrence;
53      Info : in out String;
54      Ptr  : in out Natural);
55   pragma Import
56     (Ada, Append_Info_Exception_Message, "__gnat_append_info_e_msg");
57
58   procedure Append_Info_Untailored_Exception_Information
59     (X    : Exception_Occurrence;
60      Info : in out String;
61      Ptr  : in out Natural);
62   pragma Import
63     (Ada, Append_Info_Untailored_Exception_Information,
64      "__gnat_append_info_u_e_info");
65
66   procedure To_Stderr (S : String);
67   pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
68   --  Little routine to output string to stderr
69
70   Gnat_Argv : System.Address;
71   pragma Import (C, Gnat_Argv, "gnat_argv");
72
73   procedure Fill_Arg (A : System.Address; Arg_Num : Integer);
74   pragma Import (C, Fill_Arg, "__gnat_fill_arg");
75
76   function Len_Arg (Arg_Num : Integer) return Integer;
77   pragma Import (C, Len_Arg, "__gnat_len_arg");
78
79   Ptr   : Natural := 0;
80   Nobuf : String (1 .. 0);
81
82   Nline : constant String := String'(1 => ASCII.LF);
83   --  Convenient shortcut
84
85begin
86   --  Do not execute any task termination code when shutting down the system.
87   --  The Adafinal procedure would execute the task termination routine for
88   --  normal termination, but we have already executed the task termination
89   --  procedure because of an unhandled exception.
90
91   System.Soft_Links.Task_Termination_Handler :=
92     System.Soft_Links.Task_Termination_NT'Access;
93
94   --  We shutdown the runtime now. The rest of the procedure needs to be
95   --  careful not to use anything that would require runtime support. In
96   --  particular, functions returning strings are banned since the sec stack
97   --  is no longer functional. This is particularly important to note for the
98   --  Exception_Information output. We used to allow the tailored version to
99   --  show up here, which turned out to be a bad idea as it might involve a
100   --  traceback decorator the length of which we don't control. Potentially
101   --  heavy primary/secondary stack use or dynamic allocations right before
102   --  this point are not welcome, moving the output before the finalization
103   --  raises order of outputs concerns, and decorators are intended to only
104   --  be used with exception traces, which should have been issued already.
105
106   System.Standard_Library.Adafinal;
107
108   --  Print a message only when exception traces are not active
109
110   if Exception_Trace /= RM_Convention then
111      null;
112
113   --  Check for special case of raising _ABORT_SIGNAL, which is not
114   --  really an exception at all. We recognize this by the fact that
115   --  it is the only exception whose name starts with underscore.
116
117   elsif To_Ptr (Except.Id.Full_Name) (1) = '_' then
118      To_Stderr (Nline);
119      To_Stderr ("Execution terminated by abort of environment task");
120      To_Stderr (Nline);
121
122   --  If no tracebacks, we print the unhandled exception in the old style
123   --  (i.e. the style used before ZCX was implemented). We do this to
124   --  retain compatibility.
125
126   elsif Except.Num_Tracebacks = 0 then
127      To_Stderr (Nline);
128      To_Stderr ("raised ");
129      To_Stderr
130        (To_Ptr (Except.Id.Full_Name) (1 .. Except.Id.Name_Length - 1));
131
132      if Exception_Message_Length (Except) /= 0 then
133         To_Stderr (" : ");
134         Append_Info_Exception_Message (Except, Nobuf, Ptr);
135      end if;
136
137      To_Stderr (Nline);
138
139   --  Traceback exists
140
141   else
142      To_Stderr (Nline);
143
144      if Gnat_Argv = System.Null_Address then
145         To_Stderr ("Execution terminated by unhandled exception");
146      else
147         declare
148            Arg : aliased String (1 .. Len_Arg (0));
149         begin
150            Fill_Arg (Arg'Address, 0);
151            To_Stderr ("Execution of ");
152            To_Stderr (Arg);
153            To_Stderr (" terminated by unhandled exception");
154         end;
155      end if;
156
157      To_Stderr (Nline);
158
159      Append_Info_Untailored_Exception_Information (Except, Nobuf, Ptr);
160   end if;
161
162   Unhandled_Terminate;
163end Ada.Exceptions.Last_Chance_Handler;
164