1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--                SYSTEM.TASK_PRIMITIVES.OPERATIONS.SPECIFIC                --
6--                                                                          --
7--                                B o d y                                   --
8--                                                                          --
9--         Copyright (C) 1992-2019, Free Software Foundation, Inc.          --
10--                                                                          --
11-- GNARL 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-- GNARL was developed by the GNARL team at Florida State University.       --
28-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This is a POSIX version of this package where foreign threads are
33--  recognized.
34
35separate (System.Task_Primitives.Operations)
36package body Specific is
37
38   ATCB_Key : aliased pthread_key_t;
39   --  Key used to find the Ada Task_Id associated with a thread
40
41   ----------------
42   -- Initialize --
43   ----------------
44
45   procedure Initialize (Environment_Task : Task_Id) is
46      pragma Warnings (Off, Environment_Task);
47      Result : Interfaces.C.int;
48
49   begin
50      Result := pthread_key_create (ATCB_Key'Access, null);
51      pragma Assert (Result = 0);
52   end Initialize;
53
54   -------------------
55   -- Is_Valid_Task --
56   -------------------
57
58   function Is_Valid_Task return Boolean is
59   begin
60      return pthread_getspecific (ATCB_Key) /= System.Null_Address;
61   end Is_Valid_Task;
62
63   ---------
64   -- Set --
65   ---------
66
67   procedure Set (Self_Id : Task_Id) is
68      Result : Interfaces.C.int;
69   begin
70      Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));
71      pragma Assert (Result = 0);
72   end Set;
73
74   ----------
75   -- Self --
76   ----------
77
78   --  To make Ada tasks and C threads interoperate better, we have added some
79   --  functionality to Self. Suppose a C main program (with threads) calls an
80   --  Ada procedure and the Ada procedure calls the tasking runtime system.
81   --  Eventually, a call will be made to self. Since the call is not coming
82   --  from an Ada task, there will be no corresponding ATCB.
83
84   --  What we do in Self is to catch references that do not come from
85   --  recognized Ada tasks, and create an ATCB for the calling thread.
86
87   --  The new ATCB will be "detached" from the normal Ada task master
88   --  hierarchy, much like the existing implicitly created signal-server
89   --  tasks.
90
91   function Self return Task_Id is
92      Result : System.Address;
93
94   begin
95      Result := pthread_getspecific (ATCB_Key);
96
97      --  If the key value is Null then it is a non-Ada task
98
99      if Result /= System.Null_Address then
100         return To_Task_Id (Result);
101      else
102         return Register_Foreign_Thread;
103      end if;
104   end Self;
105
106end Specific;
107