gcc/ada/s-taprop-posix.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2016, 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-like version of this package
  33
  34 --  This package contains all the GNULL primitives that interface directly with
  35 --  the underlying OS.
  36
  37 --  Note: this file can only be used for POSIX compliant systems that implement
  38 --  SCHED_FIFO and Ceiling Locking correctly.
  39
  40 --  For configurations where SCHED_FIFO and priority ceiling are not a
  41 --  requirement, this file can also be used (e.g AiX threads)
  42
  43 pragma Polling (Off);
  44 --  Turn off polling, we do not want ATC polling to take place during tasking
  45 --  operations. It causes infinite loops and other problems.
  46
  47 with Ada.Unchecked_Conversion;
  48
  49 with Interfaces.C;
  50
  51 with System.Tasking.Debug;
  52 with System.Interrupt_Management;
  53 with System.OS_Constants;
  54 with System.OS_Primitives;
  55 with System.Task_Info;
  56
  57 with System.Soft_Links;
  58 --  We use System.Soft_Links instead of System.Tasking.Initialization
  59 --  because the later is a higher level package that we shouldn't depend on.
  60 --  For example when using the restricted run time, it is replaced by
  61 --  System.Tasking.Restricted.Stages.
  62
  63 package body System.Task_Primitives.Operations is
  64
  65    package OSC renames System.OS_Constants;
  66    package SSL renames System.Soft_Links;
  67
  68    use System.Tasking.Debug;
  69    use System.Tasking;
  70    use Interfaces.C;
  71    use System.OS_Interface;
  72    use System.Parameters;
  73    use System.OS_Primitives;
  74
  75    ----------------
  76    -- Local Data --
  77    ----------------
  78
  79    --  The followings are logically constants, but need to be initialized
  80    --  at run time.
  81
  82    Single_RTS_Lock : aliased RTS_Lock;
  83    --  This is a lock to allow only one thread of control in the RTS at
  84    --  a time; it is used to execute in mutual exclusion from all other tasks.
  85    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  86
  87    Environment_Task_Id : Task_Id;
  88    --  A variable to hold Task_Id for the environment task
  89
  90    Locking_Policy : Character;
  91    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  92    --  Value of the pragma Locking_Policy:
  93    --    'C' for Ceiling_Locking
  94    --    'I' for Inherit_Locking
  95    --    ' ' for none.
  96
  97    Unblocked_Signal_Mask : aliased sigset_t;
  98    --  The set of signals that should unblocked in all tasks
  99
 100    --  The followings are internal configuration constants needed
 101
 102    Next_Serial_Number : Task_Serial_Number := 100;
 103    --  We start at 100, to reserve some special values for
 104    --  using in error checking.
 105
 106    Time_Slice_Val : Integer;
 107    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 108
 109    Dispatching_Policy : Character;
 110    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 111
 112    Foreign_Task_Elaborated : aliased Boolean := True;
 113    --  Used to identified fake tasks (i.e., non-Ada Threads)
 114
 115    Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
 116    --  Whether to use an alternate signal stack for stack overflows
 117
 118    Abort_Handler_Installed : Boolean := False;
 119    --  True if a handler for the abort signal is installed
 120
 121    --------------------
 122    -- Local Packages --
 123    --------------------
 124
 125    package Specific is
 126
 127       procedure Initialize (Environment_Task : Task_Id);
 128       pragma Inline (Initialize);
 129       --  Initialize various data needed by this package
 130
 131       function Is_Valid_Task return Boolean;
 132       pragma Inline (Is_Valid_Task);
 133       --  Does executing thread have a TCB?
 134
 135       procedure Set (Self_Id : Task_Id);
 136       pragma Inline (Set);
 137       --  Set the self id for the current task
 138
 139       function Self return Task_Id;
 140       pragma Inline (Self);
 141       --  Return a pointer to the Ada Task Control Block of the calling task
 142
 143    end Specific;
 144
 145    package body Specific is separate;
 146    --  The body of this package is target specific
 147
 148    ----------------------------------
 149    -- ATCB allocation/deallocation --
 150    ----------------------------------
 151
 152    package body ATCB_Allocation is separate;
 153    --  The body of this package is shared across several targets
 154
 155    ---------------------------------
 156    -- Support for foreign threads --
 157    ---------------------------------
 158
 159    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 160    --  Allocate and Initialize a new ATCB for the current Thread
 161
 162    function Register_Foreign_Thread
 163      (Thread : Thread_Id) return Task_Id is separate;
 164
 165    -----------------------
 166    -- Local Subprograms --
 167    -----------------------
 168
 169    procedure Abort_Handler (Sig : Signal);
 170    --  Signal handler used to implement asynchronous abort.
 171    --  See also comment before body, below.
 172
 173    function To_Address is
 174      new Ada.Unchecked_Conversion (Task_Id, System.Address);
 175
 176    function GNAT_pthread_condattr_setup
 177      (attr : access pthread_condattr_t) return int;
 178    pragma Import (C,
 179      GNAT_pthread_condattr_setup, "__gnat_pthread_condattr_setup");
 180
 181    procedure Compute_Deadline
 182      (Time       : Duration;
 183       Mode       : ST.Delay_Modes;
 184       Check_Time : out Duration;
 185       Abs_Time   : out Duration;
 186       Rel_Time   : out Duration);
 187    --  Helper for Timed_Sleep and Timed_Delay: given a deadline specified by
 188    --  Time and Mode, compute the current clock reading (Check_Time), and the
 189    --  target absolute and relative clock readings (Abs_Time, Rel_Time). The
 190    --  epoch for Time depends on Mode; the epoch for Check_Time and Abs_Time
 191    --  is always that of CLOCK_RT_Ada.
 192
 193    -------------------
 194    -- Abort_Handler --
 195    -------------------
 196
 197    --  Target-dependent binding of inter-thread Abort signal to the raising of
 198    --  the Abort_Signal exception.
 199
 200    --  The technical issues and alternatives here are essentially the
 201    --  same as for raising exceptions in response to other signals
 202    --  (e.g. Storage_Error). See code and comments in the package body
 203    --  System.Interrupt_Management.
 204
 205    --  Some implementations may not allow an exception to be propagated out of
 206    --  a handler, and others might leave the signal or interrupt that invoked
 207    --  this handler masked after the exceptional return to the application
 208    --  code.
 209
 210    --  GNAT exceptions are originally implemented using setjmp()/longjmp(). On
 211    --  most UNIX systems, this will allow transfer out of a signal handler,
 212    --  which is usually the only mechanism available for implementing
 213    --  asynchronous handlers of this kind. However, some systems do not
 214    --  restore the signal mask on longjmp(), leaving the abort signal masked.
 215
 216    procedure Abort_Handler (Sig : Signal) is
 217       pragma Unreferenced (Sig);
 218
 219       T       : constant Task_Id := Self;
 220       Old_Set : aliased sigset_t;
 221
 222       Result : Interfaces.C.int;
 223       pragma Warnings (Off, Result);
 224
 225    begin
 226       --  It's not safe to raise an exception when using GCC ZCX mechanism.
 227       --  Note that we still need to install a signal handler, since in some
 228       --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we
 229       --  need to send the Abort signal to a task.
 230
 231       if ZCX_By_Default then
 232          return;
 233       end if;
 234
 235       if T.Deferral_Level = 0
 236         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 237         not T.Aborting
 238       then
 239          T.Aborting := True;
 240
 241          --  Make sure signals used for RTS internal purpose are unmasked
 242
 243          Result := pthread_sigmask (SIG_UNBLOCK,
 244            Unblocked_Signal_Mask'Access, Old_Set'Access);
 245          pragma Assert (Result = 0);
 246
 247          raise Standard'Abort_Signal;
 248       end if;
 249    end Abort_Handler;
 250
 251    ----------------------
 252    -- Compute_Deadline --
 253    ----------------------
 254
 255    procedure Compute_Deadline
 256      (Time       : Duration;
 257       Mode       : ST.Delay_Modes;
 258       Check_Time : out Duration;
 259       Abs_Time   : out Duration;
 260       Rel_Time   : out Duration)
 261    is
 262    begin
 263       Check_Time := Monotonic_Clock;
 264
 265       --  Relative deadline
 266
 267       if Mode = Relative then
 268          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 269
 270          if Relative_Timed_Wait then
 271             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 272          end if;
 273
 274          pragma Warnings (Off);
 275          --  Comparison "OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME" is compile
 276          --  time known.
 277
 278       --  Absolute deadline specified using the tasking clock (CLOCK_RT_Ada)
 279
 280       elsif Mode = Absolute_RT
 281         or else OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME
 282       then
 283          pragma Warnings (On);
 284          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 285
 286          if Relative_Timed_Wait then
 287             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 288          end if;
 289
 290       --  Absolute deadline specified using the calendar clock, in the
 291       --  case where it is not the same as the tasking clock: compensate for
 292       --  difference between clock epochs (Base_Time - Base_Cal_Time).
 293
 294       else
 295          declare
 296             Cal_Check_Time : constant Duration := OS_Primitives.Clock;
 297             RT_Time        : constant Duration :=
 298                                Time + Check_Time - Cal_Check_Time;
 299
 300          begin
 301             Abs_Time :=
 302               Duration'Min (Check_Time + Max_Sensible_Delay, RT_Time);
 303
 304             if Relative_Timed_Wait then
 305                Rel_Time :=
 306                  Duration'Min (Max_Sensible_Delay, RT_Time - Check_Time);
 307             end if;
 308          end;
 309       end if;
 310    end Compute_Deadline;
 311
 312    -----------------
 313    -- Stack_Guard --
 314    -----------------
 315
 316    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 317       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 318       Page_Size  : Address;
 319       Res        : Interfaces.C.int;
 320
 321    begin
 322       if Stack_Base_Available then
 323
 324          --  Compute the guard page address
 325
 326          Page_Size := Address (Get_Page_Size);
 327          Res :=
 328            mprotect
 329              (Stack_Base - (Stack_Base mod Page_Size) + Page_Size,
 330               size_t (Page_Size),
 331               prot => (if On then PROT_ON else PROT_OFF));
 332          pragma Assert (Res = 0);
 333       end if;
 334    end Stack_Guard;
 335
 336    --------------------
 337    -- Get_Thread_Id  --
 338    --------------------
 339
 340    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 341    begin
 342       return T.Common.LL.Thread;
 343    end Get_Thread_Id;
 344
 345    ----------
 346    -- Self --
 347    ----------
 348
 349    function Self return Task_Id renames Specific.Self;
 350
 351    ---------------------
 352    -- Initialize_Lock --
 353    ---------------------
 354
 355    --  Note: mutexes and cond_variables needed per-task basis are initialized
 356    --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such
 357    --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any
 358    --  status change of RTS. Therefore raising Storage_Error in the following
 359    --  routines should be able to be handled safely.
 360
 361    procedure Initialize_Lock
 362      (Prio : System.Any_Priority;
 363       L    : not null access Lock)
 364    is
 365       Attributes : aliased pthread_mutexattr_t;
 366       Result : Interfaces.C.int;
 367
 368    begin
 369       Result := pthread_mutexattr_init (Attributes'Access);
 370       pragma Assert (Result = 0 or else Result = ENOMEM);
 371
 372       if Result = ENOMEM then
 373          raise Storage_Error;
 374       end if;
 375
 376       if Locking_Policy = 'C' then
 377          Result := pthread_mutexattr_setprotocol
 378            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 379          pragma Assert (Result = 0);
 380
 381          Result := pthread_mutexattr_setprioceiling
 382             (Attributes'Access, Interfaces.C.int (Prio));
 383          pragma Assert (Result = 0);
 384
 385       elsif Locking_Policy = 'I' then
 386          Result := pthread_mutexattr_setprotocol
 387            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 388          pragma Assert (Result = 0);
 389       end if;
 390
 391       Result := pthread_mutex_init (L.WO'Access, Attributes'Access);
 392       pragma Assert (Result = 0 or else Result = ENOMEM);
 393
 394       if Result = ENOMEM then
 395          Result := pthread_mutexattr_destroy (Attributes'Access);
 396          raise Storage_Error;
 397       end if;
 398
 399       Result := pthread_mutexattr_destroy (Attributes'Access);
 400       pragma Assert (Result = 0);
 401    end Initialize_Lock;
 402
 403    procedure Initialize_Lock
 404      (L : not null access RTS_Lock; Level : Lock_Level)
 405    is
 406       pragma Unreferenced (Level);
 407
 408       Attributes : aliased pthread_mutexattr_t;
 409       Result     : Interfaces.C.int;
 410
 411    begin
 412       Result := pthread_mutexattr_init (Attributes'Access);
 413       pragma Assert (Result = 0 or else Result = ENOMEM);
 414
 415       if Result = ENOMEM then
 416          raise Storage_Error;
 417       end if;
 418
 419       if Locking_Policy = 'C' then
 420          Result := pthread_mutexattr_setprotocol
 421            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 422          pragma Assert (Result = 0);
 423
 424          Result := pthread_mutexattr_setprioceiling
 425             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 426          pragma Assert (Result = 0);
 427
 428       elsif Locking_Policy = 'I' then
 429          Result := pthread_mutexattr_setprotocol
 430            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 431          pragma Assert (Result = 0);
 432       end if;
 433
 434       Result := pthread_mutex_init (L, Attributes'Access);
 435       pragma Assert (Result = 0 or else Result = ENOMEM);
 436
 437       if Result = ENOMEM then
 438          Result := pthread_mutexattr_destroy (Attributes'Access);
 439          raise Storage_Error;
 440       end if;
 441
 442       Result := pthread_mutexattr_destroy (Attributes'Access);
 443       pragma Assert (Result = 0);
 444    end Initialize_Lock;
 445
 446    -------------------
 447    -- Finalize_Lock --
 448    -------------------
 449
 450    procedure Finalize_Lock (L : not null access Lock) is
 451       Result : Interfaces.C.int;
 452    begin
 453       Result := pthread_mutex_destroy (L.WO'Access);
 454       pragma Assert (Result = 0);
 455    end Finalize_Lock;
 456
 457    procedure Finalize_Lock (L : not null access RTS_Lock) is
 458       Result : Interfaces.C.int;
 459    begin
 460       Result := pthread_mutex_destroy (L);
 461       pragma Assert (Result = 0);
 462    end Finalize_Lock;
 463
 464    ----------------
 465    -- Write_Lock --
 466    ----------------
 467
 468    procedure Write_Lock
 469      (L : not null access Lock; Ceiling_Violation : out Boolean)
 470    is
 471       Result : Interfaces.C.int;
 472
 473    begin
 474       Result := pthread_mutex_lock (L.WO'Access);
 475
 476       --  The cause of EINVAL is a priority ceiling violation
 477
 478       Ceiling_Violation := Result = EINVAL;
 479       pragma Assert (Result = 0 or else Ceiling_Violation);
 480    end Write_Lock;
 481
 482    procedure Write_Lock
 483      (L           : not null access RTS_Lock;
 484       Global_Lock : Boolean := False)
 485    is
 486       Result : Interfaces.C.int;
 487    begin
 488       if not Single_Lock or else Global_Lock then
 489          Result := pthread_mutex_lock (L);
 490          pragma Assert (Result = 0);
 491       end if;
 492    end Write_Lock;
 493
 494    procedure Write_Lock (T : Task_Id) is
 495       Result : Interfaces.C.int;
 496    begin
 497       if not Single_Lock then
 498          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 499          pragma Assert (Result = 0);
 500       end if;
 501    end Write_Lock;
 502
 503    ---------------
 504    -- Read_Lock --
 505    ---------------
 506
 507    procedure Read_Lock
 508      (L : not null access Lock; Ceiling_Violation : out Boolean) is
 509    begin
 510       Write_Lock (L, Ceiling_Violation);
 511    end Read_Lock;
 512
 513    ------------
 514    -- Unlock --
 515    ------------
 516
 517    procedure Unlock (L : not null access Lock) is
 518       Result : Interfaces.C.int;
 519    begin
 520       Result := pthread_mutex_unlock (L.WO'Access);
 521       pragma Assert (Result = 0);
 522    end Unlock;
 523
 524    procedure Unlock
 525      (L : not null access RTS_Lock; Global_Lock : Boolean := False)
 526    is
 527       Result : Interfaces.C.int;
 528    begin
 529       if not Single_Lock or else Global_Lock then
 530          Result := pthread_mutex_unlock (L);
 531          pragma Assert (Result = 0);
 532       end if;
 533    end Unlock;
 534
 535    procedure Unlock (T : Task_Id) is
 536       Result : Interfaces.C.int;
 537    begin
 538       if not Single_Lock then
 539          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 540          pragma Assert (Result = 0);
 541       end if;
 542    end Unlock;
 543
 544    -----------------
 545    -- Set_Ceiling --
 546    -----------------
 547
 548    --  Dynamic priority ceilings are not supported by the underlying system
 549
 550    procedure Set_Ceiling
 551      (L    : not null access Lock;
 552       Prio : System.Any_Priority)
 553    is
 554       pragma Unreferenced (L, Prio);
 555    begin
 556       null;
 557    end Set_Ceiling;
 558
 559    -----------
 560    -- Sleep --
 561    -----------
 562
 563    procedure Sleep
 564      (Self_ID : Task_Id;
 565       Reason  : System.Tasking.Task_States)
 566    is
 567       pragma Unreferenced (Reason);
 568
 569       Result : Interfaces.C.int;
 570
 571    begin
 572       Result :=
 573         pthread_cond_wait
 574           (cond  => Self_ID.Common.LL.CV'Access,
 575            mutex => (if Single_Lock
 576                      then Single_RTS_Lock'Access
 577                      else Self_ID.Common.LL.L'Access));
 578
 579       --  EINTR is not considered a failure
 580
 581       pragma Assert (Result = 0 or else Result = EINTR);
 582    end Sleep;
 583
 584    -----------------
 585    -- Timed_Sleep --
 586    -----------------
 587
 588    --  This is for use within the run-time system, so abort is
 589    --  assumed to be already deferred, and the caller should be
 590    --  holding its own ATCB lock.
 591
 592    procedure Timed_Sleep
 593      (Self_ID  : Task_Id;
 594       Time     : Duration;
 595       Mode     : ST.Delay_Modes;
 596       Reason   : Task_States;
 597       Timedout : out Boolean;
 598       Yielded  : out Boolean)
 599    is
 600       pragma Unreferenced (Reason);
 601
 602       Base_Time  : Duration;
 603       Check_Time : Duration;
 604       Abs_Time   : Duration;
 605       Rel_Time   : Duration;
 606
 607       Request    : aliased timespec;
 608       Result     : Interfaces.C.int;
 609
 610    begin
 611       Timedout := True;
 612       Yielded := False;
 613
 614       Compute_Deadline
 615         (Time       => Time,
 616          Mode       => Mode,
 617          Check_Time => Check_Time,
 618          Abs_Time   => Abs_Time,
 619          Rel_Time   => Rel_Time);
 620       Base_Time := Check_Time;
 621
 622       if Abs_Time > Check_Time then
 623          Request :=
 624            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 625
 626          loop
 627             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 628
 629             Result :=
 630               pthread_cond_timedwait
 631                 (cond    => Self_ID.Common.LL.CV'Access,
 632                  mutex   => (if Single_Lock
 633                              then Single_RTS_Lock'Access
 634                              else Self_ID.Common.LL.L'Access),
 635                  abstime => Request'Access);
 636
 637             Check_Time := Monotonic_Clock;
 638             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 639
 640             if Result = 0 or Result = EINTR then
 641
 642                --  Somebody may have called Wakeup for us
 643
 644                Timedout := False;
 645                exit;
 646             end if;
 647
 648             pragma Assert (Result = ETIMEDOUT);
 649          end loop;
 650       end if;
 651    end Timed_Sleep;
 652
 653    -----------------
 654    -- Timed_Delay --
 655    -----------------
 656
 657    --  This is for use in implementing delay statements, so we assume the
 658    --  caller is abort-deferred but is holding no locks.
 659
 660    procedure Timed_Delay
 661      (Self_ID : Task_Id;
 662       Time    : Duration;
 663       Mode    : ST.Delay_Modes)
 664    is
 665       Base_Time  : Duration;
 666       Check_Time : Duration;
 667       Abs_Time   : Duration;
 668       Rel_Time   : Duration;
 669       Request    : aliased timespec;
 670
 671       Result : Interfaces.C.int;
 672       pragma Warnings (Off, Result);
 673
 674    begin
 675       if Single_Lock then
 676          Lock_RTS;
 677       end if;
 678
 679       Write_Lock (Self_ID);
 680
 681       Compute_Deadline
 682         (Time       => Time,
 683          Mode       => Mode,
 684          Check_Time => Check_Time,
 685          Abs_Time   => Abs_Time,
 686          Rel_Time   => Rel_Time);
 687       Base_Time := Check_Time;
 688
 689       if Abs_Time > Check_Time then
 690          Request :=
 691            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 692          Self_ID.Common.State := Delay_Sleep;
 693
 694          loop
 695             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 696
 697             Result :=
 698               pthread_cond_timedwait
 699                 (cond    => Self_ID.Common.LL.CV'Access,
 700                  mutex   => (if Single_Lock
 701                              then Single_RTS_Lock'Access
 702                              else Self_ID.Common.LL.L'Access),
 703                  abstime => Request'Access);
 704
 705             Check_Time := Monotonic_Clock;
 706             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 707
 708             pragma Assert (Result = 0
 709                              or else Result = ETIMEDOUT
 710                              or else Result = EINTR);
 711          end loop;
 712
 713          Self_ID.Common.State := Runnable;
 714       end if;
 715
 716       Unlock (Self_ID);
 717
 718       if Single_Lock then
 719          Unlock_RTS;
 720       end if;
 721
 722       Result := sched_yield;
 723    end Timed_Delay;
 724
 725    ---------------------
 726    -- Monotonic_Clock --
 727    ---------------------
 728
 729    function Monotonic_Clock return Duration is
 730       TS     : aliased timespec;
 731       Result : Interfaces.C.int;
 732    begin
 733       Result := clock_gettime
 734         (clock_id => OSC.CLOCK_RT_Ada, tp => TS'Unchecked_Access);
 735       pragma Assert (Result = 0);
 736       return To_Duration (TS);
 737    end Monotonic_Clock;
 738
 739    -------------------
 740    -- RT_Resolution --
 741    -------------------
 742
 743    function RT_Resolution return Duration is
 744       TS     : aliased timespec;
 745       Result : Interfaces.C.int;
 746    begin
 747       Result := clock_getres (OSC.CLOCK_REALTIME, TS'Unchecked_Access);
 748       pragma Assert (Result = 0);
 749
 750       return To_Duration (TS);
 751    end RT_Resolution;
 752
 753    ------------
 754    -- Wakeup --
 755    ------------
 756
 757    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 758       pragma Unreferenced (Reason);
 759       Result : Interfaces.C.int;
 760    begin
 761       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 762       pragma Assert (Result = 0);
 763    end Wakeup;
 764
 765    -----------
 766    -- Yield --
 767    -----------
 768
 769    procedure Yield (Do_Yield : Boolean := True) is
 770       Result : Interfaces.C.int;
 771       pragma Unreferenced (Result);
 772    begin
 773       if Do_Yield then
 774          Result := sched_yield;
 775       end if;
 776    end Yield;
 777
 778    ------------------
 779    -- Set_Priority --
 780    ------------------
 781
 782    procedure Set_Priority
 783      (T                   : Task_Id;
 784       Prio                : System.Any_Priority;
 785       Loss_Of_Inheritance : Boolean := False)
 786    is
 787       pragma Unreferenced (Loss_Of_Inheritance);
 788
 789       Result : Interfaces.C.int;
 790       Param  : aliased struct_sched_param;
 791
 792       function Get_Policy (Prio : System.Any_Priority) return Character;
 793       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 794       --  Get priority specific dispatching policy
 795
 796       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 797       --  Upper case first character of the policy name corresponding to the
 798       --  task as set by a Priority_Specific_Dispatching pragma.
 799
 800    begin
 801       T.Common.Current_Priority := Prio;
 802       Param.sched_priority := To_Target_Priority (Prio);
 803
 804       if Time_Slice_Supported
 805         and then (Dispatching_Policy = 'R'
 806                   or else Priority_Specific_Policy = 'R'
 807                   or else Time_Slice_Val > 0)
 808       then
 809          Result := pthread_setschedparam
 810            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 811
 812       elsif Dispatching_Policy = 'F'
 813         or else Priority_Specific_Policy = 'F'
 814         or else Time_Slice_Val = 0
 815       then
 816          Result := pthread_setschedparam
 817            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 818
 819       else
 820          Result := pthread_setschedparam
 821            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 822       end if;
 823
 824       pragma Assert (Result = 0);
 825    end Set_Priority;
 826
 827    ------------------
 828    -- Get_Priority --
 829    ------------------
 830
 831    function Get_Priority (T : Task_Id) return System.Any_Priority is
 832    begin
 833       return T.Common.Current_Priority;
 834    end Get_Priority;
 835
 836    ----------------
 837    -- Enter_Task --
 838    ----------------
 839
 840    procedure Enter_Task (Self_ID : Task_Id) is
 841    begin
 842       Self_ID.Common.LL.Thread := pthread_self;
 843       Self_ID.Common.LL.LWP := lwp_self;
 844
 845       Specific.Set (Self_ID);
 846
 847       if Use_Alternate_Stack then
 848          declare
 849             Stack  : aliased stack_t;
 850             Result : Interfaces.C.int;
 851          begin
 852             Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;
 853             Stack.ss_size  := Alternate_Stack_Size;
 854             Stack.ss_flags := 0;
 855             Result := sigaltstack (Stack'Access, null);
 856             pragma Assert (Result = 0);
 857          end;
 858       end if;
 859    end Enter_Task;
 860
 861    -------------------
 862    -- Is_Valid_Task --
 863    -------------------
 864
 865    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 866
 867    -----------------------------
 868    -- Register_Foreign_Thread --
 869    -----------------------------
 870
 871    function Register_Foreign_Thread return Task_Id is
 872    begin
 873       if Is_Valid_Task then
 874          return Self;
 875       else
 876          return Register_Foreign_Thread (pthread_self);
 877       end if;
 878    end Register_Foreign_Thread;
 879
 880    --------------------
 881    -- Initialize_TCB --
 882    --------------------
 883
 884    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 885       Mutex_Attr : aliased pthread_mutexattr_t;
 886       Result     : Interfaces.C.int;
 887       Cond_Attr  : aliased pthread_condattr_t;
 888
 889    begin
 890       --  Give the task a unique serial number
 891
 892       Self_ID.Serial_Number := Next_Serial_Number;
 893       Next_Serial_Number := Next_Serial_Number + 1;
 894       pragma Assert (Next_Serial_Number /= 0);
 895
 896       if not Single_Lock then
 897          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 898          pragma Assert (Result = 0 or else Result = ENOMEM);
 899
 900          if Result = 0 then
 901             if Locking_Policy = 'C' then
 902                Result :=
 903                  pthread_mutexattr_setprotocol
 904                    (Mutex_Attr'Access,
 905                     PTHREAD_PRIO_PROTECT);
 906                pragma Assert (Result = 0);
 907
 908                Result :=
 909                  pthread_mutexattr_setprioceiling
 910                    (Mutex_Attr'Access,
 911                     Interfaces.C.int (System.Any_Priority'Last));
 912                pragma Assert (Result = 0);
 913
 914             elsif Locking_Policy = 'I' then
 915                Result :=
 916                  pthread_mutexattr_setprotocol
 917                    (Mutex_Attr'Access,
 918                     PTHREAD_PRIO_INHERIT);
 919                pragma Assert (Result = 0);
 920             end if;
 921
 922             Result :=
 923               pthread_mutex_init
 924                 (Self_ID.Common.LL.L'Access,
 925                  Mutex_Attr'Access);
 926             pragma Assert (Result = 0 or else Result = ENOMEM);
 927          end if;
 928
 929          if Result /= 0 then
 930             Succeeded := False;
 931             return;
 932          end if;
 933
 934          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 935          pragma Assert (Result = 0);
 936       end if;
 937
 938       Result := pthread_condattr_init (Cond_Attr'Access);
 939       pragma Assert (Result = 0 or else Result = ENOMEM);
 940
 941       if Result = 0 then
 942          Result := GNAT_pthread_condattr_setup (Cond_Attr'Access);
 943          pragma Assert (Result = 0);
 944
 945          Result :=
 946            pthread_cond_init
 947              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 948          pragma Assert (Result = 0 or else Result = ENOMEM);
 949       end if;
 950
 951       if Result = 0 then
 952          Succeeded := True;
 953       else
 954          if not Single_Lock then
 955             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 956             pragma Assert (Result = 0);
 957          end if;
 958
 959          Succeeded := False;
 960       end if;
 961
 962       Result := pthread_condattr_destroy (Cond_Attr'Access);
 963       pragma Assert (Result = 0);
 964    end Initialize_TCB;
 965
 966    -----------------
 967    -- Create_Task --
 968    -----------------
 969
 970    procedure Create_Task
 971      (T          : Task_Id;
 972       Wrapper    : System.Address;
 973       Stack_Size : System.Parameters.Size_Type;
 974       Priority   : System.Any_Priority;
 975       Succeeded  : out Boolean)
 976    is
 977       Attributes          : aliased pthread_attr_t;
 978       Adjusted_Stack_Size : Interfaces.C.size_t;
 979       Page_Size           : constant Interfaces.C.size_t :=
 980                               Interfaces.C.size_t (Get_Page_Size);
 981       Result              : Interfaces.C.int;
 982
 983       function Thread_Body_Access is new
 984         Ada.Unchecked_Conversion (System.Address, Thread_Body);
 985
 986       use System.Task_Info;
 987
 988    begin
 989       Adjusted_Stack_Size :=
 990          Interfaces.C.size_t (Stack_Size + Alternate_Stack_Size);
 991
 992       if Stack_Base_Available then
 993
 994          --  If Stack Checking is supported then allocate 2 additional pages:
 995
 996          --  In the worst case, stack is allocated at something like
 997          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 998          --  to be sure the effective stack size is greater than what
 999          --  has been asked.
1000
1001          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Page_Size;
1002       end if;
1003
1004       --  Round stack size as this is required by some OSes (Darwin)
1005
1006       Adjusted_Stack_Size := Adjusted_Stack_Size + Page_Size - 1;
1007       Adjusted_Stack_Size :=
1008         Adjusted_Stack_Size - Adjusted_Stack_Size mod Page_Size;
1009
1010       Result := pthread_attr_init (Attributes'Access);
1011       pragma Assert (Result = 0 or else Result = ENOMEM);
1012
1013       if Result /= 0 then
1014          Succeeded := False;
1015          return;
1016       end if;
1017
1018       Result :=
1019         pthread_attr_setdetachstate
1020           (Attributes'Access, PTHREAD_CREATE_DETACHED);
1021       pragma Assert (Result = 0);
1022
1023       Result :=
1024         pthread_attr_setstacksize
1025           (Attributes'Access, Adjusted_Stack_Size);
1026       pragma Assert (Result = 0);
1027
1028       if T.Common.Task_Info /= Default_Scope then
1029          case T.Common.Task_Info is
1030             when System.Task_Info.Process_Scope =>
1031                Result :=
1032                  pthread_attr_setscope
1033                    (Attributes'Access, PTHREAD_SCOPE_PROCESS);
1034
1035             when System.Task_Info.System_Scope =>
1036                Result :=
1037                  pthread_attr_setscope
1038                    (Attributes'Access, PTHREAD_SCOPE_SYSTEM);
1039
1040             when System.Task_Info.Default_Scope =>
1041                Result := 0;
1042          end case;
1043
1044          pragma Assert (Result = 0);
1045       end if;
1046
1047       --  Since the initial signal mask of a thread is inherited from the
1048       --  creator, and the Environment task has all its signals masked, we
1049       --  do not need to manipulate caller's signal mask at this point.
1050       --  All tasks in RTS will have All_Tasks_Mask initially.
1051
1052       --  Note: the use of Unrestricted_Access in the following call is needed
1053       --  because otherwise we have an error of getting a access-to-volatile
1054       --  value which points to a non-volatile object. But in this case it is
1055       --  safe to do this, since we know we have no problems with aliasing and
1056       --  Unrestricted_Access bypasses this check.
1057
1058       Result := pthread_create
1059         (T.Common.LL.Thread'Unrestricted_Access,
1060          Attributes'Access,
1061          Thread_Body_Access (Wrapper),
1062          To_Address (T));
1063       pragma Assert (Result = 0 or else Result = EAGAIN);
1064
1065       Succeeded := Result = 0;
1066
1067       Result := pthread_attr_destroy (Attributes'Access);
1068       pragma Assert (Result = 0);
1069
1070       if Succeeded then
1071          Set_Priority (T, Priority);
1072       end if;
1073    end Create_Task;
1074
1075    ------------------
1076    -- Finalize_TCB --
1077    ------------------
1078
1079    procedure Finalize_TCB (T : Task_Id) is
1080       Result : Interfaces.C.int;
1081
1082    begin
1083       if not Single_Lock then
1084          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1085          pragma Assert (Result = 0);
1086       end if;
1087
1088       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1089       pragma Assert (Result = 0);
1090
1091       if T.Known_Tasks_Index /= -1 then
1092          Known_Tasks (T.Known_Tasks_Index) := null;
1093       end if;
1094
1095       ATCB_Allocation.Free_ATCB (T);
1096    end Finalize_TCB;
1097
1098    ---------------
1099    -- Exit_Task --
1100    ---------------
1101
1102    procedure Exit_Task is
1103    begin
1104       --  Mark this task as unknown, so that if Self is called, it won't
1105       --  return a dangling pointer.
1106
1107       Specific.Set (null);
1108    end Exit_Task;
1109
1110    ----------------
1111    -- Abort_Task --
1112    ----------------
1113
1114    procedure Abort_Task (T : Task_Id) is
1115       Result : Interfaces.C.int;
1116    begin
1117       if Abort_Handler_Installed then
1118          Result :=
1119            pthread_kill
1120              (T.Common.LL.Thread,
1121               Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1122          pragma Assert (Result = 0);
1123       end if;
1124    end Abort_Task;
1125
1126    ----------------
1127    -- Initialize --
1128    ----------------
1129
1130    procedure Initialize (S : in out Suspension_Object) is
1131       Mutex_Attr : aliased pthread_mutexattr_t;
1132       Cond_Attr  : aliased pthread_condattr_t;
1133       Result     : Interfaces.C.int;
1134
1135    begin
1136       --  Initialize internal state (always to False (RM D.10 (6)))
1137
1138       S.State := False;
1139       S.Waiting := False;
1140
1141       --  Initialize internal mutex
1142
1143       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1144       pragma Assert (Result = 0 or else Result = ENOMEM);
1145
1146       if Result = ENOMEM then
1147          raise Storage_Error;
1148       end if;
1149
1150       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1151       pragma Assert (Result = 0 or else Result = ENOMEM);
1152
1153       if Result = ENOMEM then
1154          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1155          pragma Assert (Result = 0);
1156
1157          raise Storage_Error;
1158       end if;
1159
1160       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1161       pragma Assert (Result = 0);
1162
1163       --  Initialize internal condition variable
1164
1165       Result := pthread_condattr_init (Cond_Attr'Access);
1166       pragma Assert (Result = 0 or else Result = ENOMEM);
1167
1168       if Result /= 0 then
1169          Result := pthread_mutex_destroy (S.L'Access);
1170          pragma Assert (Result = 0);
1171
1172          --  Storage_Error is propagated as intended if the allocation of the
1173          --  underlying OS entities fails.
1174
1175          raise Storage_Error;
1176
1177       else
1178          Result := GNAT_pthread_condattr_setup (Cond_Attr'Access);
1179          pragma Assert (Result = 0);
1180       end if;
1181
1182       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1183       pragma Assert (Result = 0 or else Result = ENOMEM);
1184
1185       if Result /= 0 then
1186          Result := pthread_mutex_destroy (S.L'Access);
1187          pragma Assert (Result = 0);
1188
1189          Result := pthread_condattr_destroy (Cond_Attr'Access);
1190          pragma Assert (Result = 0);
1191
1192          --  Storage_Error is propagated as intended if the allocation of the
1193          --  underlying OS entities fails.
1194
1195          raise Storage_Error;
1196       end if;
1197
1198       Result := pthread_condattr_destroy (Cond_Attr'Access);
1199       pragma Assert (Result = 0);
1200    end Initialize;
1201
1202    --------------
1203    -- Finalize --
1204    --------------
1205
1206    procedure Finalize (S : in out Suspension_Object) is
1207       Result : Interfaces.C.int;
1208
1209    begin
1210       --  Destroy internal mutex
1211
1212       Result := pthread_mutex_destroy (S.L'Access);
1213       pragma Assert (Result = 0);
1214
1215       --  Destroy internal condition variable
1216
1217       Result := pthread_cond_destroy (S.CV'Access);
1218       pragma Assert (Result = 0);
1219    end Finalize;
1220
1221    -------------------
1222    -- Current_State --
1223    -------------------
1224
1225    function Current_State (S : Suspension_Object) return Boolean is
1226    begin
1227       --  We do not want to use lock on this read operation. State is marked
1228       --  as Atomic so that we ensure that the value retrieved is correct.
1229
1230       return S.State;
1231    end Current_State;
1232
1233    ---------------
1234    -- Set_False --
1235    ---------------
1236
1237    procedure Set_False (S : in out Suspension_Object) is
1238       Result : Interfaces.C.int;
1239
1240    begin
1241       SSL.Abort_Defer.all;
1242
1243       Result := pthread_mutex_lock (S.L'Access);
1244       pragma Assert (Result = 0);
1245
1246       S.State := False;
1247
1248       Result := pthread_mutex_unlock (S.L'Access);
1249       pragma Assert (Result = 0);
1250
1251       SSL.Abort_Undefer.all;
1252    end Set_False;
1253
1254    --------------
1255    -- Set_True --
1256    --------------
1257
1258    procedure Set_True (S : in out Suspension_Object) is
1259       Result : Interfaces.C.int;
1260
1261    begin
1262       SSL.Abort_Defer.all;
1263
1264       Result := pthread_mutex_lock (S.L'Access);
1265       pragma Assert (Result = 0);
1266
1267       --  If there is already a task waiting on this suspension object then
1268       --  we resume it, leaving the state of the suspension object to False,
1269       --  as it is specified in (RM D.10(9)). Otherwise, it just leaves
1270       --  the state to True.
1271
1272       if S.Waiting then
1273          S.Waiting := False;
1274          S.State := False;
1275
1276          Result := pthread_cond_signal (S.CV'Access);
1277          pragma Assert (Result = 0);
1278
1279       else
1280          S.State := True;
1281       end if;
1282
1283       Result := pthread_mutex_unlock (S.L'Access);
1284       pragma Assert (Result = 0);
1285
1286       SSL.Abort_Undefer.all;
1287    end Set_True;
1288
1289    ------------------------
1290    -- Suspend_Until_True --
1291    ------------------------
1292
1293    procedure Suspend_Until_True (S : in out Suspension_Object) is
1294       Result : Interfaces.C.int;
1295
1296    begin
1297       SSL.Abort_Defer.all;
1298
1299       Result := pthread_mutex_lock (S.L'Access);
1300       pragma Assert (Result = 0);
1301
1302       if S.Waiting then
1303
1304          --  Program_Error must be raised upon calling Suspend_Until_True
1305          --  if another task is already waiting on that suspension object
1306          --  (RM D.10(10)).
1307
1308          Result := pthread_mutex_unlock (S.L'Access);
1309          pragma Assert (Result = 0);
1310
1311          SSL.Abort_Undefer.all;
1312
1313          raise Program_Error;
1314
1315       else
1316          --  Suspend the task if the state is False. Otherwise, the task
1317          --  continues its execution, and the state of the suspension object
1318          --  is set to False (ARM D.10 par. 9).
1319
1320          if S.State then
1321             S.State := False;
1322          else
1323             S.Waiting := True;
1324
1325             loop
1326                --  Loop in case pthread_cond_wait returns earlier than expected
1327                --  (e.g. in case of EINTR caused by a signal).
1328
1329                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1330                pragma Assert (Result = 0 or else Result = EINTR);
1331
1332                exit when not S.Waiting;
1333             end loop;
1334          end if;
1335
1336          Result := pthread_mutex_unlock (S.L'Access);
1337          pragma Assert (Result = 0);
1338
1339          SSL.Abort_Undefer.all;
1340       end if;
1341    end Suspend_Until_True;
1342
1343    ----------------
1344    -- Check_Exit --
1345    ----------------
1346
1347    --  Dummy version
1348
1349    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1350       pragma Unreferenced (Self_ID);
1351    begin
1352       return True;
1353    end Check_Exit;
1354
1355    --------------------
1356    -- Check_No_Locks --
1357    --------------------
1358
1359    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1360       pragma Unreferenced (Self_ID);
1361    begin
1362       return True;
1363    end Check_No_Locks;
1364
1365    ----------------------
1366    -- Environment_Task --
1367    ----------------------
1368
1369    function Environment_Task return Task_Id is
1370    begin
1371       return Environment_Task_Id;
1372    end Environment_Task;
1373
1374    --------------
1375    -- Lock_RTS --
1376    --------------
1377
1378    procedure Lock_RTS is
1379    begin
1380       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1381    end Lock_RTS;
1382
1383    ----------------
1384    -- Unlock_RTS --
1385    ----------------
1386
1387    procedure Unlock_RTS is
1388    begin
1389       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1390    end Unlock_RTS;
1391
1392    ------------------
1393    -- Suspend_Task --
1394    ------------------
1395
1396    function Suspend_Task
1397      (T           : ST.Task_Id;
1398       Thread_Self : Thread_Id) return Boolean
1399    is
1400       pragma Unreferenced (T, Thread_Self);
1401    begin
1402       return False;
1403    end Suspend_Task;
1404
1405    -----------------
1406    -- Resume_Task --
1407    -----------------
1408
1409    function Resume_Task
1410      (T           : ST.Task_Id;
1411       Thread_Self : Thread_Id) return Boolean
1412    is
1413       pragma Unreferenced (T, Thread_Self);
1414    begin
1415       return False;
1416    end Resume_Task;
1417
1418    --------------------
1419    -- Stop_All_Tasks --
1420    --------------------
1421
1422    procedure Stop_All_Tasks is
1423    begin
1424       null;
1425    end Stop_All_Tasks;
1426
1427    ---------------
1428    -- Stop_Task --
1429    ---------------
1430
1431    function Stop_Task (T : ST.Task_Id) return Boolean is
1432       pragma Unreferenced (T);
1433    begin
1434       return False;
1435    end Stop_Task;
1436
1437    -------------------
1438    -- Continue_Task --
1439    -------------------
1440
1441    function Continue_Task (T : ST.Task_Id) return Boolean is
1442       pragma Unreferenced (T);
1443    begin
1444       return False;
1445    end Continue_Task;
1446
1447    ----------------
1448    -- Initialize --
1449    ----------------
1450
1451    procedure Initialize (Environment_Task : Task_Id) is
1452       act     : aliased struct_sigaction;
1453       old_act : aliased struct_sigaction;
1454       Tmp_Set : aliased sigset_t;
1455       Result  : Interfaces.C.int;
1456
1457       function State
1458         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1459       pragma Import (C, State, "__gnat_get_interrupt_state");
1460       --  Get interrupt state.  Defined in a-init.c
1461       --  The input argument is the interrupt number,
1462       --  and the result is one of the following:
1463
1464       Default : constant Character := 's';
1465       --    'n'   this interrupt not set by any Interrupt_State pragma
1466       --    'u'   Interrupt_State pragma set state to User
1467       --    'r'   Interrupt_State pragma set state to Runtime
1468       --    's'   Interrupt_State pragma set state to System (use "default"
1469       --           system handler)
1470
1471    begin
1472       Environment_Task_Id := Environment_Task;
1473
1474       Interrupt_Management.Initialize;
1475
1476       --  Prepare the set of signals that should unblocked in all tasks
1477
1478       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1479       pragma Assert (Result = 0);
1480
1481       for J in Interrupt_Management.Interrupt_ID loop
1482          if System.Interrupt_Management.Keep_Unmasked (J) then
1483             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1484             pragma Assert (Result = 0);
1485          end if;
1486       end loop;
1487
1488       --  Initialize the lock used to synchronize chain of all ATCBs
1489
1490       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1491
1492       Specific.Initialize (Environment_Task);
1493
1494       if Use_Alternate_Stack then
1495          Environment_Task.Common.Task_Alternate_Stack :=
1496            Alternate_Stack'Address;
1497       end if;
1498
1499       --  Make environment task known here because it doesn't go through
1500       --  Activate_Tasks, which does it for all other tasks.
1501
1502       Known_Tasks (Known_Tasks'First) := Environment_Task;
1503       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1504
1505       Enter_Task (Environment_Task);
1506
1507       if State
1508           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1509       then
1510          act.sa_flags := 0;
1511          act.sa_handler := Abort_Handler'Address;
1512
1513          Result := sigemptyset (Tmp_Set'Access);
1514          pragma Assert (Result = 0);
1515          act.sa_mask := Tmp_Set;
1516
1517          Result :=
1518            sigaction
1519              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1520               act'Unchecked_Access,
1521               old_act'Unchecked_Access);
1522          pragma Assert (Result = 0);
1523          Abort_Handler_Installed := True;
1524       end if;
1525    end Initialize;
1526
1527    -----------------------
1528    -- Set_Task_Affinity --
1529    -----------------------
1530
1531    procedure Set_Task_Affinity (T : ST.Task_Id) is
1532       pragma Unreferenced (T);
1533
1534    begin
1535       --  Setting task affinity is not supported by the underlying system
1536
1537       null;
1538    end Set_Task_Affinity;
1539
1540 end System.Task_Primitives.Operations;