1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--             S Y S T E M . S O F T _ L I N K S . T A S K I N G            --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 2004-2013, 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
32pragma Style_Checks (All_Checks);
33--  Turn off subprogram alpha ordering check, since we group soft link bodies
34--  and dummy soft link bodies together separately in this unit.
35
36pragma Polling (Off);
37--  Turn polling off for this package. We don't need polling during any of the
38--  routines in this package, and more to the point, if we try to poll it can
39--  cause infinite loops.
40
41with Ada.Exceptions;
42with Ada.Exceptions.Is_Null_Occurrence;
43
44with System.Task_Primitives.Operations;
45with System.Tasking;
46with System.Stack_Checking;
47
48package body System.Soft_Links.Tasking is
49
50   package STPO renames System.Task_Primitives.Operations;
51   package SSL  renames System.Soft_Links;
52
53   use Ada.Exceptions;
54
55   use type System.Tasking.Task_Id;
56   use type System.Tasking.Termination_Handler;
57
58   ----------------
59   -- Local Data --
60   ----------------
61
62   Initialized : Boolean := False;
63   --  Boolean flag that indicates whether the tasking soft links have
64   --  already been set.
65
66   -----------------------------------------------------------------
67   -- Tasking Versions of Services Needed by Non-Tasking Programs --
68   -----------------------------------------------------------------
69
70   function  Get_Jmpbuf_Address return  Address;
71   procedure Set_Jmpbuf_Address (Addr : Address);
72   --  Get/Set Jmpbuf_Address for current task
73
74   function  Get_Sec_Stack_Addr return  Address;
75   procedure Set_Sec_Stack_Addr (Addr : Address);
76   --  Get/Set location of current task's secondary stack
77
78   procedure Timed_Delay_T (Time : Duration; Mode : Integer);
79   --  Task-safe version of SSL.Timed_Delay
80
81   procedure Task_Termination_Handler_T  (Excep : SSL.EO);
82   --  Task-safe version of the task termination procedure
83
84   function Get_Stack_Info return Stack_Checking.Stack_Access;
85   --  Get access to the current task's Stack_Info
86
87   --------------------------
88   -- Soft-Link Get Bodies --
89   --------------------------
90
91   function Get_Jmpbuf_Address return  Address is
92   begin
93      return STPO.Self.Common.Compiler_Data.Jmpbuf_Address;
94   end Get_Jmpbuf_Address;
95
96   function Get_Sec_Stack_Addr return  Address is
97   begin
98      return STPO.Self.Common.Compiler_Data.Sec_Stack_Addr;
99   end Get_Sec_Stack_Addr;
100
101   function Get_Stack_Info return Stack_Checking.Stack_Access is
102   begin
103      return STPO.Self.Common.Compiler_Data.Pri_Stack_Info'Access;
104   end Get_Stack_Info;
105
106   --------------------------
107   -- Soft-Link Set Bodies --
108   --------------------------
109
110   procedure Set_Jmpbuf_Address (Addr : Address) is
111   begin
112      STPO.Self.Common.Compiler_Data.Jmpbuf_Address := Addr;
113   end Set_Jmpbuf_Address;
114
115   procedure Set_Sec_Stack_Addr (Addr : Address) is
116   begin
117      STPO.Self.Common.Compiler_Data.Sec_Stack_Addr := Addr;
118   end Set_Sec_Stack_Addr;
119
120   -------------------
121   -- Timed_Delay_T --
122   -------------------
123
124   procedure Timed_Delay_T (Time : Duration; Mode : Integer) is
125      Self_Id : constant System.Tasking.Task_Id := STPO.Self;
126
127   begin
128      --  In case pragma Detect_Blocking is active then Program_Error
129      --  must be raised if this potentially blocking operation
130      --  is called from a protected operation.
131
132      if System.Tasking.Detect_Blocking
133        and then Self_Id.Common.Protected_Action_Nesting > 0
134      then
135         raise Program_Error with "potentially blocking operation";
136      else
137         Abort_Defer.all;
138         STPO.Timed_Delay (Self_Id, Time, Mode);
139         Abort_Undefer.all;
140      end if;
141   end Timed_Delay_T;
142
143   --------------------------------
144   -- Task_Termination_Handler_T --
145   --------------------------------
146
147   procedure Task_Termination_Handler_T (Excep : SSL.EO) is
148      Self_Id : constant System.Tasking.Task_Id := STPO.Self;
149      Cause   : System.Tasking.Cause_Of_Termination;
150      EO      : Ada.Exceptions.Exception_Occurrence;
151
152   begin
153      --  We can only be here because we are terminating the environment task.
154      --  Task termination for all other tasks is handled in the Task_Wrapper.
155
156      --  We do not want to enable this check and e.g. call System.OS_Lib.Abort
157      --  here because some restricted run-times may not have System.OS_Lib
158      --  (e.g. JVM), and calling abort may do more harm than good to the
159      --  main application.
160
161      pragma Assert (Self_Id = STPO.Environment_Task);
162
163      --  Normal task termination
164
165      if Is_Null_Occurrence (Excep) then
166         Cause := System.Tasking.Normal;
167         Ada.Exceptions.Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
168
169      --  Abnormal task termination
170
171      elsif Exception_Identity (Excep) = Standard'Abort_Signal'Identity then
172         Cause := System.Tasking.Abnormal;
173         Ada.Exceptions.Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
174
175      --  Termination because of an unhandled exception
176
177      else
178         Cause := System.Tasking.Unhandled_Exception;
179         Ada.Exceptions.Save_Occurrence (EO, Excep);
180      end if;
181
182      --  There is no need for explicit protection against race conditions for
183      --  this part because it can only be executed by the environment task
184      --  after all the other tasks have been finalized. Note that there is no
185      --  fall-back handler which could apply to this environment task because
186      --  it has no parents, and, as specified in ARM C.7.3 par. 9/2, "the
187      --  fall-back handler applies only to the dependent tasks of the task".
188
189      if Self_Id.Common.Specific_Handler /= null then
190         Self_Id.Common.Specific_Handler.all (Cause, Self_Id, EO);
191      end if;
192   end Task_Termination_Handler_T;
193
194   -----------------------------
195   -- Init_Tasking_Soft_Links --
196   -----------------------------
197
198   procedure Init_Tasking_Soft_Links is
199   begin
200      --  Set links only if not set already
201
202      if not Initialized then
203
204         --  Mark tasking soft links as initialized
205
206         Initialized := True;
207
208         --  The application being executed uses tasking so that the tasking
209         --  version of the following soft links need to be used.
210
211         SSL.Get_Jmpbuf_Address       := Get_Jmpbuf_Address'Access;
212         SSL.Set_Jmpbuf_Address       := Set_Jmpbuf_Address'Access;
213         SSL.Get_Sec_Stack_Addr       := Get_Sec_Stack_Addr'Access;
214         SSL.Get_Stack_Info           := Get_Stack_Info'Access;
215         SSL.Set_Sec_Stack_Addr       := Set_Sec_Stack_Addr'Access;
216         SSL.Timed_Delay              := Timed_Delay_T'Access;
217         SSL.Task_Termination_Handler := Task_Termination_Handler_T'Access;
218
219         --  No need to create a new secondary stack, since we will use the
220         --  default one created in s-secsta.adb.
221
222         SSL.Set_Sec_Stack_Addr     (SSL.Get_Sec_Stack_Addr_NT);
223         SSL.Set_Jmpbuf_Address     (SSL.Get_Jmpbuf_Address_NT);
224      end if;
225   end Init_Tasking_Soft_Links;
226
227end System.Soft_Links.Tasking;
228