1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                      ADA.EXCEPTIONS.EXCEPTION_TRACES                     --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 1992-2012, 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 (Exception_Trace = Unhandled_Raise and then Is_Unhandled))
89      then
90         --  Exception trace messages need to be protected when several tasks
91         --  can issue them at the same time.
92
93         Lock_Task.all;
94         To_Stderr (Nline);
95
96         if Is_Unhandled then
97            To_Stderr ("Unhandled ");
98         end if;
99
100         To_Stderr ("Exception raised");
101         To_Stderr (Nline);
102         To_Stderr (Tailored_Exception_Information (Excep.all));
103         Unlock_Task.all;
104      end if;
105
106      --  Call the user-specific actions
107      --  ??? We should presumably look at the reraise status here.
108
109      if Raise_Hook_Initialized
110        and then Exception_Data_Ptr (Excep.Id).Raise_Hook /= null
111      then
112         To_Action (Exception_Data_Ptr (Excep.Id).Raise_Hook) (Excep.all);
113      end if;
114
115      if Global_Action /= null then
116         Global_Action (Excep.all);
117      end if;
118   end Notify_Exception;
119
120   ------------------------------
121   -- Notify_Handled_Exception --
122   ------------------------------
123
124   procedure Notify_Handled_Exception (Excep : EOA) is
125   begin
126      Notify_Exception (Excep, Is_Unhandled => False);
127   end Notify_Handled_Exception;
128
129   --------------------------------
130   -- Notify_Unhandled_Exception --
131   --------------------------------
132
133   procedure Notify_Unhandled_Exception (Excep : EOA) is
134   begin
135      --  Check whether there is any termination handler to be executed for
136      --  the environment task, and execute it if needed. Here we handle both
137      --  the Abnormal and Unhandled_Exception task termination. Normal
138      --  task termination routine is executed elsewhere (either in the
139      --  Task_Wrapper or in the Adafinal routine for the environment task).
140
141      Task_Termination_Handler.all (Excep.all);
142
143      Notify_Exception (Excep, Is_Unhandled => True);
144      Debug_Unhandled_Exception (SSL.Exception_Data_Ptr (Excep.Id));
145   end Notify_Unhandled_Exception;
146
147   -----------------------------------
148   -- Unhandled_Exception_Terminate --
149   -----------------------------------
150
151   procedure Unhandled_Exception_Terminate (Excep : EOA) is
152      Occ : Exception_Occurrence;
153      --  This occurrence will be used to display a message after finalization.
154      --  It is necessary to save a copy here, or else the designated value
155      --  could be overwritten if an exception is raised during finalization
156      --  (even if that exception is caught). The occurrence is saved on the
157      --  stack to avoid dynamic allocation (if this exception is due to lack
158      --  of space in the heap, we therefore avoid a second failure). We assume
159      --  that there is enough room on the stack however.
160
161   begin
162      Save_Occurrence (Occ, Excep.all);
163      Last_Chance_Handler (Occ);
164   end Unhandled_Exception_Terminate;
165
166   ------------------------------------
167   -- Handling GNAT.Exception_Traces --
168   ------------------------------------
169
170   --  The bulk of exception traces output is centralized in Notify_Exception,
171   --  for both the Handled and Unhandled cases. Extra task specific output is
172   --  triggered in the task wrapper for unhandled occurrences in tasks. It is
173   --  not performed in this unit to avoid dragging dependencies against the
174   --  tasking units here.
175
176   --  We used to rely on the output performed by Unhanded_Exception_Terminate
177   --  for the case of an unhandled occurrence in the environment thread, and
178   --  the task wrapper was responsible for the whole output in the tasking
179   --  case.
180
181   --  This initial scheme had a drawback: the output from Terminate only
182   --  occurs after finalization is done, which means possibly never if some
183   --  tasks keep hanging around.
184
185   --  The first "presumably obvious" fix consists in moving the Terminate
186   --  output before the finalization. It has not been retained because it
187   --  introduces annoying changes in output orders when the finalization
188   --  itself issues outputs, this also in "regular" cases not resorting to
189   --  Exception_Traces.
190
191   --  Today's solution has the advantage of simplicity and better isolates
192   --  the Exception_Traces machinery.
193
194   --  It currently outputs the information about unhandled exceptions twice
195   --  in the environment thread, once in the notification routine and once in
196   --  the termination routine. Avoiding the second output is possible but so
197   --  far has been considered undesirable. It would mean changing the order
198   --  of outputs between the two runs with or without exception traces, while
199   --  it seems preferable to only have additional outputs in the former
200   --  case.
201
202end Exception_Traces;
203