1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                      ADA.EXCEPTIONS.EXCEPTION_TRACES                     --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 1992-2015, 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
32with Ada.Unchecked_Conversion;
33
34pragma Warnings (Off);
35with Ada.Exceptions.Last_Chance_Handler;
36pragma Warnings (On);
37--  Bring last chance handler into closure
38
39separate (Ada.Exceptions)
40package body Exception_Traces is
41
42   Nline : constant String := String'(1 => ASCII.LF);
43   --  Convenient shortcut
44
45   type Exception_Action is access procedure (E : Exception_Occurrence);
46   Global_Action : Exception_Action := null;
47   pragma Export
48     (Ada, Global_Action, "__gnat_exception_actions_global_action");
49   --  Global action, executed whenever an exception is raised.  Changing the
50   --  export name must be coordinated with code in g-excact.adb.
51
52   Raise_Hook_Initialized : Boolean := False;
53   pragma Export
54     (Ada, Raise_Hook_Initialized, "__gnat_exception_actions_initialized");
55
56   procedure Last_Chance_Handler (Except : Exception_Occurrence);
57   pragma Import (C, Last_Chance_Handler, "__gnat_last_chance_handler");
58   pragma No_Return (Last_Chance_Handler);
59   --  Users can replace the default version of this routine,
60   --  Ada.Exceptions.Last_Chance_Handler.
61
62   function To_Action is new Ada.Unchecked_Conversion
63     (Raise_Action, Exception_Action);
64
65   -----------------------
66   -- Local Subprograms --
67   -----------------------
68
69   procedure Notify_Exception (Excep : EOA; Is_Unhandled : Boolean);
70   --  Factorizes the common processing for Notify_Handled_Exception and
71   --  Notify_Unhandled_Exception. Is_Unhandled is set to True only in the
72   --  latter case because Notify_Handled_Exception may be called for an
73   --  actually unhandled occurrence in the Front-End-SJLJ case.
74
75   ----------------------
76   -- Notify_Exception --
77   ----------------------
78
79   procedure Notify_Exception (Excep : EOA; Is_Unhandled : Boolean) is
80   begin
81      --  Output the exception information required by the Exception_Trace
82      --  configuration. Take care not to output information about internal
83      --  exceptions.
84
85      if not Excep.Id.Not_Handled_By_Others
86        and then
87          (Exception_Trace = Every_Raise
88            or else
89              (Is_Unhandled
90                and then
91                  (Exception_Trace = Unhandled_Raise
92                    or else Exception_Trace = Unhandled_Raise_In_Main)))
93      then
94         --  Exception trace messages need to be protected when several tasks
95         --  can issue them at the same time.
96
97         Lock_Task.all;
98         To_Stderr (Nline);
99
100         if Exception_Trace /= Unhandled_Raise_In_Main then
101            if Is_Unhandled then
102               To_Stderr ("Unhandled ");
103            end if;
104
105            To_Stderr ("Exception raised");
106            To_Stderr (Nline);
107         end if;
108
109         To_Stderr (Exception_Information (Excep.all));
110         Unlock_Task.all;
111      end if;
112
113      --  Call the user-specific actions
114      --  ??? We should presumably look at the reraise status here.
115
116      if Raise_Hook_Initialized
117        and then Exception_Data_Ptr (Excep.Id).Raise_Hook /= null
118      then
119         To_Action (Exception_Data_Ptr (Excep.Id).Raise_Hook) (Excep.all);
120      end if;
121
122      if Global_Action /= null then
123         Global_Action (Excep.all);
124      end if;
125   end Notify_Exception;
126
127   ------------------------------
128   -- Notify_Handled_Exception --
129   ------------------------------
130
131   procedure Notify_Handled_Exception (Excep : EOA) is
132   begin
133      Notify_Exception (Excep, Is_Unhandled => False);
134   end Notify_Handled_Exception;
135
136   --------------------------------
137   -- Notify_Unhandled_Exception --
138   --------------------------------
139
140   procedure Notify_Unhandled_Exception (Excep : EOA) is
141   begin
142      --  Check whether there is any termination handler to be executed for
143      --  the environment task, and execute it if needed. Here we handle both
144      --  the Abnormal and Unhandled_Exception task termination. Normal
145      --  task termination routine is executed elsewhere (either in the
146      --  Task_Wrapper or in the Adafinal routine for the environment task).
147
148      Task_Termination_Handler.all (Excep.all);
149
150      Notify_Exception (Excep, Is_Unhandled => True);
151      Debug_Unhandled_Exception (SSL.Exception_Data_Ptr (Excep.Id));
152   end Notify_Unhandled_Exception;
153
154   -----------------------------------
155   -- Unhandled_Exception_Terminate --
156   -----------------------------------
157
158   procedure Unhandled_Exception_Terminate (Excep : EOA) is
159      Occ : Exception_Occurrence;
160      --  This occurrence will be used to display a message after finalization.
161      --  It is necessary to save a copy here, or else the designated value
162      --  could be overwritten if an exception is raised during finalization
163      --  (even if that exception is caught). The occurrence is saved on the
164      --  stack to avoid dynamic allocation (if this exception is due to lack
165      --  of space in the heap, we therefore avoid a second failure). We assume
166      --  that there is enough room on the stack however.
167
168   begin
169      Save_Occurrence (Occ, Excep.all);
170      Last_Chance_Handler (Occ);
171   end Unhandled_Exception_Terminate;
172
173   ------------------------------------
174   -- Handling GNAT.Exception_Traces --
175   ------------------------------------
176
177   --  The bulk of exception traces output is centralized in Notify_Exception,
178   --  for both the Handled and Unhandled cases. Extra task specific output is
179   --  triggered in the task wrapper for unhandled occurrences in tasks. It is
180   --  not performed in this unit to avoid dependencies on the tasking units
181   --  here.
182
183   --  We used to rely on the output performed by Unhanded_Exception_Terminate
184   --  for the case of an unhandled occurrence in the environment thread, and
185   --  the task wrapper was responsible for the whole output in the tasking
186   --  case.
187
188   --  This initial scheme had a drawback: the output from Terminate only
189   --  occurs after finalization is done, which means possibly never if some
190   --  tasks keep hanging around.
191
192   --  The first "presumably obvious" fix consists in moving the Terminate
193   --  output before the finalization. It has not been retained because it
194   --  introduces annoying changes in output orders when the finalization
195   --  itself issues outputs, this also in "regular" cases not resorting to
196   --  Exception_Traces.
197
198   --  Today's solution has the advantage of simplicity and better isolates
199   --  the Exception_Traces machinery.
200
201end Exception_Traces;
202