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) 1992-2014, 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 :=
 297                                OS_Primitives.Monotonic_Clock;
 298             RT_Time        : constant Duration :=
 299                                Time + Check_Time - Cal_Check_Time;
 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       Guard_Page_Address : Address;
 319
 320       Res : Interfaces.C.int;
 321
 322    begin
 323       if Stack_Base_Available then
 324
 325          --  Compute the guard page address
 326
 327          Guard_Page_Address :=
 328            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 329
 330          Res :=
 331            mprotect (Guard_Page_Address, Get_Page_Size,
 332                      prot => (if On then PROT_ON else PROT_OFF));
 333          pragma Assert (Res = 0);
 334       end if;
 335    end Stack_Guard;
 336
 337    --------------------
 338    -- Get_Thread_Id  --
 339    --------------------
 340
 341    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 342    begin
 343       return T.Common.LL.Thread;
 344    end Get_Thread_Id;
 345
 346    ----------
 347    -- Self --
 348    ----------
 349
 350    function Self return Task_Id renames Specific.Self;
 351
 352    ---------------------
 353    -- Initialize_Lock --
 354    ---------------------
 355
 356    --  Note: mutexes and cond_variables needed per-task basis are
 357    --        initialized in Initialize_TCB and the Storage_Error is
 358    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 359    --        used in RTS is initialized before any status change of RTS.
 360    --        Therefore raising Storage_Error in the following routines
 361    --        should be able to be handled safely.
 362
 363    procedure Initialize_Lock
 364      (Prio : System.Any_Priority;
 365       L    : not null access Lock)
 366    is
 367       Attributes : aliased pthread_mutexattr_t;
 368       Result : Interfaces.C.int;
 369
 370    begin
 371       Result := pthread_mutexattr_init (Attributes'Access);
 372       pragma Assert (Result = 0 or else Result = ENOMEM);
 373
 374       if Result = ENOMEM then
 375          raise Storage_Error;
 376       end if;
 377
 378       if Locking_Policy = 'C' then
 379          Result := pthread_mutexattr_setprotocol
 380            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 381          pragma Assert (Result = 0);
 382
 383          Result := pthread_mutexattr_setprioceiling
 384             (Attributes'Access, Interfaces.C.int (Prio));
 385          pragma Assert (Result = 0);
 386
 387       elsif Locking_Policy = 'I' then
 388          Result := pthread_mutexattr_setprotocol
 389            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 390          pragma Assert (Result = 0);
 391       end if;
 392
 393       Result := pthread_mutex_init (L.WO'Access, Attributes'Access);
 394       pragma Assert (Result = 0 or else Result = ENOMEM);
 395
 396       if Result = ENOMEM then
 397          Result := pthread_mutexattr_destroy (Attributes'Access);
 398          raise Storage_Error;
 399       end if;
 400
 401       Result := pthread_mutexattr_destroy (Attributes'Access);
 402       pragma Assert (Result = 0);
 403    end Initialize_Lock;
 404
 405    procedure Initialize_Lock
 406      (L : not null access RTS_Lock; Level : Lock_Level)
 407    is
 408       pragma Unreferenced (Level);
 409
 410       Attributes : aliased pthread_mutexattr_t;
 411       Result     : Interfaces.C.int;
 412
 413    begin
 414       Result := pthread_mutexattr_init (Attributes'Access);
 415       pragma Assert (Result = 0 or else Result = ENOMEM);
 416
 417       if Result = ENOMEM then
 418          raise Storage_Error;
 419       end if;
 420
 421       if Locking_Policy = 'C' then
 422          Result := pthread_mutexattr_setprotocol
 423            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 424          pragma Assert (Result = 0);
 425
 426          Result := pthread_mutexattr_setprioceiling
 427             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 428          pragma Assert (Result = 0);
 429
 430       elsif Locking_Policy = 'I' then
 431          Result := pthread_mutexattr_setprotocol
 432            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 433          pragma Assert (Result = 0);
 434       end if;
 435
 436       Result := pthread_mutex_init (L, Attributes'Access);
 437       pragma Assert (Result = 0 or else Result = ENOMEM);
 438
 439       if Result = ENOMEM then
 440          Result := pthread_mutexattr_destroy (Attributes'Access);
 441          raise Storage_Error;
 442       end if;
 443
 444       Result := pthread_mutexattr_destroy (Attributes'Access);
 445       pragma Assert (Result = 0);
 446    end Initialize_Lock;
 447
 448    -------------------
 449    -- Finalize_Lock --
 450    -------------------
 451
 452    procedure Finalize_Lock (L : not null access Lock) is
 453       Result : Interfaces.C.int;
 454    begin
 455       Result := pthread_mutex_destroy (L.WO'Access);
 456       pragma Assert (Result = 0);
 457    end Finalize_Lock;
 458
 459    procedure Finalize_Lock (L : not null access RTS_Lock) is
 460       Result : Interfaces.C.int;
 461    begin
 462       Result := pthread_mutex_destroy (L);
 463       pragma Assert (Result = 0);
 464    end Finalize_Lock;
 465
 466    ----------------
 467    -- Write_Lock --
 468    ----------------
 469
 470    procedure Write_Lock
 471      (L : not null access Lock; Ceiling_Violation : out Boolean)
 472    is
 473       Result : Interfaces.C.int;
 474
 475    begin
 476       Result := pthread_mutex_lock (L.WO'Access);
 477
 478       --  Assume that the cause of EINVAL is a priority ceiling violation
 479
 480       Ceiling_Violation := (Result = EINVAL);
 481       pragma Assert (Result = 0 or else Result = EINVAL);
 482    end Write_Lock;
 483
 484    procedure Write_Lock
 485      (L           : not null access RTS_Lock;
 486       Global_Lock : Boolean := False)
 487    is
 488       Result : Interfaces.C.int;
 489    begin
 490       if not Single_Lock or else Global_Lock then
 491          Result := pthread_mutex_lock (L);
 492          pragma Assert (Result = 0);
 493       end if;
 494    end Write_Lock;
 495
 496    procedure Write_Lock (T : Task_Id) is
 497       Result : Interfaces.C.int;
 498    begin
 499       if not Single_Lock then
 500          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 501          pragma Assert (Result = 0);
 502       end if;
 503    end Write_Lock;
 504
 505    ---------------
 506    -- Read_Lock --
 507    ---------------
 508
 509    procedure Read_Lock
 510      (L : not null access Lock; Ceiling_Violation : out Boolean) is
 511    begin
 512       Write_Lock (L, Ceiling_Violation);
 513    end Read_Lock;
 514
 515    ------------
 516    -- Unlock --
 517    ------------
 518
 519    procedure Unlock (L : not null access Lock) is
 520       Result : Interfaces.C.int;
 521    begin
 522       Result := pthread_mutex_unlock (L.WO'Access);
 523       pragma Assert (Result = 0);
 524    end Unlock;
 525
 526    procedure Unlock
 527      (L : not null access RTS_Lock; Global_Lock : Boolean := False)
 528    is
 529       Result : Interfaces.C.int;
 530    begin
 531       if not Single_Lock or else Global_Lock then
 532          Result := pthread_mutex_unlock (L);
 533          pragma Assert (Result = 0);
 534       end if;
 535    end Unlock;
 536
 537    procedure Unlock (T : Task_Id) is
 538       Result : Interfaces.C.int;
 539    begin
 540       if not Single_Lock then
 541          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 542          pragma Assert (Result = 0);
 543       end if;
 544    end Unlock;
 545
 546    -----------------
 547    -- Set_Ceiling --
 548    -----------------
 549
 550    --  Dynamic priority ceilings are not supported by the underlying system
 551
 552    procedure Set_Ceiling
 553      (L    : not null access Lock;
 554       Prio : System.Any_Priority)
 555    is
 556       pragma Unreferenced (L, Prio);
 557    begin
 558       null;
 559    end Set_Ceiling;
 560
 561    -----------
 562    -- Sleep --
 563    -----------
 564
 565    procedure Sleep
 566      (Self_ID : Task_Id;
 567       Reason  : System.Tasking.Task_States)
 568    is
 569       pragma Unreferenced (Reason);
 570
 571       Result : Interfaces.C.int;
 572
 573    begin
 574       Result :=
 575         pthread_cond_wait
 576           (cond  => Self_ID.Common.LL.CV'Access,
 577            mutex => (if Single_Lock
 578                      then Single_RTS_Lock'Access
 579                      else Self_ID.Common.LL.L'Access));
 580
 581       --  EINTR is not considered a failure
 582
 583       pragma Assert (Result = 0 or else Result = EINTR);
 584    end Sleep;
 585
 586    -----------------
 587    -- Timed_Sleep --
 588    -----------------
 589
 590    --  This is for use within the run-time system, so abort is
 591    --  assumed to be already deferred, and the caller should be
 592    --  holding its own ATCB lock.
 593
 594    procedure Timed_Sleep
 595      (Self_ID  : Task_Id;
 596       Time     : Duration;
 597       Mode     : ST.Delay_Modes;
 598       Reason   : Task_States;
 599       Timedout : out Boolean;
 600       Yielded  : out Boolean)
 601    is
 602       pragma Unreferenced (Reason);
 603
 604       Base_Time  : Duration;
 605       Check_Time : Duration;
 606       Abs_Time   : Duration;
 607       Rel_Time   : Duration;
 608
 609       Request    : aliased timespec;
 610       Result     : Interfaces.C.int;
 611
 612    begin
 613       Timedout := True;
 614       Yielded := False;
 615
 616       Compute_Deadline
 617         (Time       => Time,
 618          Mode       => Mode,
 619          Check_Time => Check_Time,
 620          Abs_Time   => Abs_Time,
 621          Rel_Time   => Rel_Time);
 622       Base_Time := Check_Time;
 623
 624       if Abs_Time > Check_Time then
 625          Request :=
 626            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 627
 628          loop
 629             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 630
 631             Result :=
 632               pthread_cond_timedwait
 633                 (cond    => Self_ID.Common.LL.CV'Access,
 634                  mutex   => (if Single_Lock
 635                              then Single_RTS_Lock'Access
 636                              else Self_ID.Common.LL.L'Access),
 637                  abstime => Request'Access);
 638
 639             Check_Time := Monotonic_Clock;
 640             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 641
 642             if Result = 0 or Result = EINTR then
 643
 644                --  Somebody may have called Wakeup for us
 645
 646                Timedout := False;
 647                exit;
 648             end if;
 649
 650             pragma Assert (Result = ETIMEDOUT);
 651          end loop;
 652       end if;
 653    end Timed_Sleep;
 654
 655    -----------------
 656    -- Timed_Delay --
 657    -----------------
 658
 659    --  This is for use in implementing delay statements, so we assume the
 660    --  caller is abort-deferred but is holding no locks.
 661
 662    procedure Timed_Delay
 663      (Self_ID : Task_Id;
 664       Time    : Duration;
 665       Mode    : ST.Delay_Modes)
 666    is
 667       Base_Time  : Duration;
 668       Check_Time : Duration;
 669       Abs_Time   : Duration;
 670       Rel_Time   : Duration;
 671       Request    : aliased timespec;
 672
 673       Result : Interfaces.C.int;
 674       pragma Warnings (Off, Result);
 675
 676    begin
 677       if Single_Lock then
 678          Lock_RTS;
 679       end if;
 680
 681       Write_Lock (Self_ID);
 682
 683       Compute_Deadline
 684         (Time       => Time,
 685          Mode       => Mode,
 686          Check_Time => Check_Time,
 687          Abs_Time   => Abs_Time,
 688          Rel_Time   => Rel_Time);
 689       Base_Time := Check_Time;
 690
 691       if Abs_Time > Check_Time then
 692          Request :=
 693            To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
 694          Self_ID.Common.State := Delay_Sleep;
 695
 696          loop
 697             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 698
 699             Result :=
 700               pthread_cond_timedwait
 701                 (cond    => Self_ID.Common.LL.CV'Access,
 702                  mutex   => (if Single_Lock
 703                              then Single_RTS_Lock'Access
 704                              else Self_ID.Common.LL.L'Access),
 705                  abstime => Request'Access);
 706
 707             Check_Time := Monotonic_Clock;
 708             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 709
 710             pragma Assert (Result = 0
 711                              or else Result = ETIMEDOUT
 712                              or else Result = EINTR);
 713          end loop;
 714
 715          Self_ID.Common.State := Runnable;
 716       end if;
 717
 718       Unlock (Self_ID);
 719
 720       if Single_Lock then
 721          Unlock_RTS;
 722       end if;
 723
 724       Result := sched_yield;
 725    end Timed_Delay;
 726
 727    ---------------------
 728    -- Monotonic_Clock --
 729    ---------------------
 730
 731    function Monotonic_Clock return Duration is
 732       TS     : aliased timespec;
 733       Result : Interfaces.C.int;
 734    begin
 735       Result := clock_gettime
 736         (clock_id => OSC.CLOCK_RT_Ada, tp => TS'Unchecked_Access);
 737       pragma Assert (Result = 0);
 738       return To_Duration (TS);
 739    end Monotonic_Clock;
 740
 741    -------------------
 742    -- RT_Resolution --
 743    -------------------
 744
 745    function RT_Resolution return Duration is
 746       TS     : aliased timespec;
 747       Result : Interfaces.C.int;
 748    begin
 749       Result := clock_getres (OSC.CLOCK_REALTIME, TS'Unchecked_Access);
 750       pragma Assert (Result = 0);
 751
 752       return To_Duration (TS);
 753    end RT_Resolution;
 754
 755    ------------
 756    -- Wakeup --
 757    ------------
 758
 759    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 760       pragma Unreferenced (Reason);
 761       Result : Interfaces.C.int;
 762    begin
 763       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 764       pragma Assert (Result = 0);
 765    end Wakeup;
 766
 767    -----------
 768    -- Yield --
 769    -----------
 770
 771    procedure Yield (Do_Yield : Boolean := True) is
 772       Result : Interfaces.C.int;
 773       pragma Unreferenced (Result);
 774    begin
 775       if Do_Yield then
 776          Result := sched_yield;
 777       end if;
 778    end Yield;
 779
 780    ------------------
 781    -- Set_Priority --
 782    ------------------
 783
 784    procedure Set_Priority
 785      (T                   : Task_Id;
 786       Prio                : System.Any_Priority;
 787       Loss_Of_Inheritance : Boolean := False)
 788    is
 789       pragma Unreferenced (Loss_Of_Inheritance);
 790
 791       Result : Interfaces.C.int;
 792       Param  : aliased struct_sched_param;
 793
 794       function Get_Policy (Prio : System.Any_Priority) return Character;
 795       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 796       --  Get priority specific dispatching policy
 797
 798       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 799       --  Upper case first character of the policy name corresponding to the
 800       --  task as set by a Priority_Specific_Dispatching pragma.
 801
 802    begin
 803       T.Common.Current_Priority := Prio;
 804       Param.sched_priority := To_Target_Priority (Prio);
 805
 806       if Time_Slice_Supported
 807         and then (Dispatching_Policy = 'R'
 808                   or else Priority_Specific_Policy = 'R'
 809                   or else Time_Slice_Val > 0)
 810       then
 811          Result := pthread_setschedparam
 812            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 813
 814       elsif Dispatching_Policy = 'F'
 815         or else Priority_Specific_Policy = 'F'
 816         or else Time_Slice_Val = 0
 817       then
 818          Result := pthread_setschedparam
 819            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 820
 821       else
 822          Result := pthread_setschedparam
 823            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 824       end if;
 825
 826       pragma Assert (Result = 0);
 827    end Set_Priority;
 828
 829    ------------------
 830    -- Get_Priority --
 831    ------------------
 832
 833    function Get_Priority (T : Task_Id) return System.Any_Priority is
 834    begin
 835       return T.Common.Current_Priority;
 836    end Get_Priority;
 837
 838    ----------------
 839    -- Enter_Task --
 840    ----------------
 841
 842    procedure Enter_Task (Self_ID : Task_Id) is
 843    begin
 844       Self_ID.Common.LL.Thread := pthread_self;
 845       Self_ID.Common.LL.LWP := lwp_self;
 846
 847       Specific.Set (Self_ID);
 848
 849       if Use_Alternate_Stack then
 850          declare
 851             Stack  : aliased stack_t;
 852             Result : Interfaces.C.int;
 853          begin
 854             Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;
 855             Stack.ss_size  := Alternate_Stack_Size;
 856             Stack.ss_flags := 0;
 857             Result := sigaltstack (Stack'Access, null);
 858             pragma Assert (Result = 0);
 859          end;
 860       end if;
 861    end Enter_Task;
 862
 863    -------------------
 864    -- Is_Valid_Task --
 865    -------------------
 866
 867    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 868
 869    -----------------------------
 870    -- Register_Foreign_Thread --
 871    -----------------------------
 872
 873    function Register_Foreign_Thread return Task_Id is
 874    begin
 875       if Is_Valid_Task then
 876          return Self;
 877       else
 878          return Register_Foreign_Thread (pthread_self);
 879       end if;
 880    end Register_Foreign_Thread;
 881
 882    --------------------
 883    -- Initialize_TCB --
 884    --------------------
 885
 886    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 887       Mutex_Attr : aliased pthread_mutexattr_t;
 888       Result     : Interfaces.C.int;
 889       Cond_Attr  : aliased pthread_condattr_t;
 890
 891    begin
 892       --  Give the task a unique serial number
 893
 894       Self_ID.Serial_Number := Next_Serial_Number;
 895       Next_Serial_Number := Next_Serial_Number + 1;
 896       pragma Assert (Next_Serial_Number /= 0);
 897
 898       if not Single_Lock then
 899          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 900          pragma Assert (Result = 0 or else Result = ENOMEM);
 901
 902          if Result = 0 then
 903             if Locking_Policy = 'C' then
 904                Result :=
 905                  pthread_mutexattr_setprotocol
 906                    (Mutex_Attr'Access,
 907                     PTHREAD_PRIO_PROTECT);
 908                pragma Assert (Result = 0);
 909
 910                Result :=
 911                  pthread_mutexattr_setprioceiling
 912                    (Mutex_Attr'Access,
 913                     Interfaces.C.int (System.Any_Priority'Last));
 914                pragma Assert (Result = 0);
 915
 916             elsif Locking_Policy = 'I' then
 917                Result :=
 918                  pthread_mutexattr_setprotocol
 919                    (Mutex_Attr'Access,
 920                     PTHREAD_PRIO_INHERIT);
 921                pragma Assert (Result = 0);
 922             end if;
 923
 924             Result :=
 925               pthread_mutex_init
 926                 (Self_ID.Common.LL.L'Access,
 927                  Mutex_Attr'Access);
 928             pragma Assert (Result = 0 or else Result = ENOMEM);
 929          end if;
 930
 931          if Result /= 0 then
 932             Succeeded := False;
 933             return;
 934          end if;
 935
 936          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 937          pragma Assert (Result = 0);
 938       end if;
 939
 940       Result := pthread_condattr_init (Cond_Attr'Access);
 941       pragma Assert (Result = 0 or else Result = ENOMEM);
 942
 943       if Result = 0 then
 944          Result := GNAT_pthread_condattr_setup (Cond_Attr'Access);
 945          pragma Assert (Result = 0);
 946
 947          Result :=
 948            pthread_cond_init
 949              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 950          pragma Assert (Result = 0 or else Result = ENOMEM);
 951       end if;
 952
 953       if Result = 0 then
 954          Succeeded := True;
 955       else
 956          if not Single_Lock then
 957             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 958             pragma Assert (Result = 0);
 959          end if;
 960
 961          Succeeded := False;
 962       end if;
 963
 964       Result := pthread_condattr_destroy (Cond_Attr'Access);
 965       pragma Assert (Result = 0);
 966    end Initialize_TCB;
 967
 968    -----------------
 969    -- Create_Task --
 970    -----------------
 971
 972    procedure Create_Task
 973      (T          : Task_Id;
 974       Wrapper    : System.Address;
 975       Stack_Size : System.Parameters.Size_Type;
 976       Priority   : System.Any_Priority;
 977       Succeeded  : out Boolean)
 978    is
 979       Attributes          : aliased pthread_attr_t;
 980       Adjusted_Stack_Size : Interfaces.C.size_t;
 981       Page_Size           : constant Interfaces.C.size_t := Get_Page_Size;
 982       Result              : Interfaces.C.int;
 983
 984       function Thread_Body_Access is new
 985         Ada.Unchecked_Conversion (System.Address, Thread_Body);
 986
 987       use System.Task_Info;
 988
 989    begin
 990       Adjusted_Stack_Size :=
 991          Interfaces.C.size_t (Stack_Size + Alternate_Stack_Size);
 992
 993       if Stack_Base_Available then
 994
 995          --  If Stack Checking is supported then allocate 2 additional pages:
 996
 997          --  In the worst case, stack is allocated at something like
 998          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 999          --  to be sure the effective stack size is greater than what
1000          --  has been asked.
1001
1002          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Page_Size;
1003       end if;
1004
1005       --  Round stack size as this is required by some OSes (Darwin)
1006
1007       Adjusted_Stack_Size := Adjusted_Stack_Size + Page_Size - 1;
1008       Adjusted_Stack_Size :=
1009         Adjusted_Stack_Size - Adjusted_Stack_Size mod Page_Size;
1010
1011       Result := pthread_attr_init (Attributes'Access);
1012       pragma Assert (Result = 0 or else Result = ENOMEM);
1013
1014       if Result /= 0 then
1015          Succeeded := False;
1016          return;
1017       end if;
1018
1019       Result :=
1020         pthread_attr_setdetachstate
1021           (Attributes'Access, PTHREAD_CREATE_DETACHED);
1022       pragma Assert (Result = 0);
1023
1024       Result :=
1025         pthread_attr_setstacksize
1026           (Attributes'Access, Adjusted_Stack_Size);
1027       pragma Assert (Result = 0);
1028
1029       if T.Common.Task_Info /= Default_Scope then
1030          case T.Common.Task_Info is
1031             when System.Task_Info.Process_Scope =>
1032                Result :=
1033                  pthread_attr_setscope
1034                    (Attributes'Access, PTHREAD_SCOPE_PROCESS);
1035
1036             when System.Task_Info.System_Scope =>
1037                Result :=
1038                  pthread_attr_setscope
1039                    (Attributes'Access, PTHREAD_SCOPE_SYSTEM);
1040
1041             when System.Task_Info.Default_Scope =>
1042                Result := 0;
1043          end case;
1044
1045          pragma Assert (Result = 0);
1046       end if;
1047
1048       --  Since the initial signal mask of a thread is inherited from the
1049       --  creator, and the Environment task has all its signals masked, we
1050       --  do not need to manipulate caller's signal mask at this point.
1051       --  All tasks in RTS will have All_Tasks_Mask initially.
1052
1053       --  Note: the use of Unrestricted_Access in the following call is needed
1054       --  because otherwise we have an error of getting a access-to-volatile
1055       --  value which points to a non-volatile object. But in this case it is
1056       --  safe to do this, since we know we have no problems with aliasing and
1057       --  Unrestricted_Access bypasses this check.
1058
1059       Result := pthread_create
1060         (T.Common.LL.Thread'Unrestricted_Access,
1061          Attributes'Access,
1062          Thread_Body_Access (Wrapper),
1063          To_Address (T));
1064       pragma Assert (Result = 0 or else Result = EAGAIN);
1065
1066       Succeeded := Result = 0;
1067
1068       Result := pthread_attr_destroy (Attributes'Access);
1069       pragma Assert (Result = 0);
1070
1071       if Succeeded then
1072          Set_Priority (T, Priority);
1073       end if;
1074    end Create_Task;
1075
1076    ------------------
1077    -- Finalize_TCB --
1078    ------------------
1079
1080    procedure Finalize_TCB (T : Task_Id) is
1081       Result : Interfaces.C.int;
1082
1083    begin
1084       if not Single_Lock then
1085          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1086          pragma Assert (Result = 0);
1087       end if;
1088
1089       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1090       pragma Assert (Result = 0);
1091
1092       if T.Known_Tasks_Index /= -1 then
1093          Known_Tasks (T.Known_Tasks_Index) := null;
1094       end if;
1095
1096       ATCB_Allocation.Free_ATCB (T);
1097    end Finalize_TCB;
1098
1099    ---------------
1100    -- Exit_Task --
1101    ---------------
1102
1103    procedure Exit_Task is
1104    begin
1105       --  Mark this task as unknown, so that if Self is called, it won't
1106       --  return a dangling pointer.
1107
1108       Specific.Set (null);
1109    end Exit_Task;
1110
1111    ----------------
1112    -- Abort_Task --
1113    ----------------
1114
1115    procedure Abort_Task (T : Task_Id) is
1116       Result : Interfaces.C.int;
1117    begin
1118       if Abort_Handler_Installed then
1119          Result :=
1120            pthread_kill
1121              (T.Common.LL.Thread,
1122               Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1123          pragma Assert (Result = 0);
1124       end if;
1125    end Abort_Task;
1126
1127    ----------------
1128    -- Initialize --
1129    ----------------
1130
1131    procedure Initialize (S : in out Suspension_Object) is
1132       Mutex_Attr : aliased pthread_mutexattr_t;
1133       Cond_Attr  : aliased pthread_condattr_t;
1134       Result     : Interfaces.C.int;
1135
1136    begin
1137       --  Initialize internal state (always to False (RM D.10 (6)))
1138
1139       S.State := False;
1140       S.Waiting := False;
1141
1142       --  Initialize internal mutex
1143
1144       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1145       pragma Assert (Result = 0 or else Result = ENOMEM);
1146
1147       if Result = ENOMEM then
1148          raise Storage_Error;
1149       end if;
1150
1151       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1152       pragma Assert (Result = 0 or else Result = ENOMEM);
1153
1154       if Result = ENOMEM then
1155          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1156          pragma Assert (Result = 0);
1157
1158          raise Storage_Error;
1159       end if;
1160
1161       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1162       pragma Assert (Result = 0);
1163
1164       --  Initialize internal condition variable
1165
1166       Result := pthread_condattr_init (Cond_Attr'Access);
1167       pragma Assert (Result = 0 or else Result = ENOMEM);
1168
1169       if Result /= 0 then
1170          Result := pthread_mutex_destroy (S.L'Access);
1171          pragma Assert (Result = 0);
1172
1173          --  Storage_Error is propagated as intended if the allocation of the
1174          --  underlying OS entities fails.
1175
1176          raise Storage_Error;
1177
1178       else
1179          Result := GNAT_pthread_condattr_setup (Cond_Attr'Access);
1180          pragma Assert (Result = 0);
1181       end if;
1182
1183       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1184       pragma Assert (Result = 0 or else Result = ENOMEM);
1185
1186       if Result /= 0 then
1187          Result := pthread_mutex_destroy (S.L'Access);
1188          pragma Assert (Result = 0);
1189
1190          Result := pthread_condattr_destroy (Cond_Attr'Access);
1191          pragma Assert (Result = 0);
1192
1193          --  Storage_Error is propagated as intended if the allocation of the
1194          --  underlying OS entities fails.
1195
1196          raise Storage_Error;
1197       end if;
1198
1199       Result := pthread_condattr_destroy (Cond_Attr'Access);
1200       pragma Assert (Result = 0);
1201    end Initialize;
1202
1203    --------------
1204    -- Finalize --
1205    --------------
1206
1207    procedure Finalize (S : in out Suspension_Object) is
1208       Result : Interfaces.C.int;
1209
1210    begin
1211       --  Destroy internal mutex
1212
1213       Result := pthread_mutex_destroy (S.L'Access);
1214       pragma Assert (Result = 0);
1215
1216       --  Destroy internal condition variable
1217
1218       Result := pthread_cond_destroy (S.CV'Access);
1219       pragma Assert (Result = 0);
1220    end Finalize;
1221
1222    -------------------
1223    -- Current_State --
1224    -------------------
1225
1226    function Current_State (S : Suspension_Object) return Boolean is
1227    begin
1228       --  We do not want to use lock on this read operation. State is marked
1229       --  as Atomic so that we ensure that the value retrieved is correct.
1230
1231       return S.State;
1232    end Current_State;
1233
1234    ---------------
1235    -- Set_False --
1236    ---------------
1237
1238    procedure Set_False (S : in out Suspension_Object) is
1239       Result : Interfaces.C.int;
1240
1241    begin
1242       SSL.Abort_Defer.all;
1243
1244       Result := pthread_mutex_lock (S.L'Access);
1245       pragma Assert (Result = 0);
1246
1247       S.State := False;
1248
1249       Result := pthread_mutex_unlock (S.L'Access);
1250       pragma Assert (Result = 0);
1251
1252       SSL.Abort_Undefer.all;
1253    end Set_False;
1254
1255    --------------
1256    -- Set_True --
1257    --------------
1258
1259    procedure Set_True (S : in out Suspension_Object) is
1260       Result : Interfaces.C.int;
1261
1262    begin
1263       SSL.Abort_Defer.all;
1264
1265       Result := pthread_mutex_lock (S.L'Access);
1266       pragma Assert (Result = 0);
1267
1268       --  If there is already a task waiting on this suspension object then
1269       --  we resume it, leaving the state of the suspension object to False,
1270       --  as it is specified in (RM D.10(9)). Otherwise, it just leaves
1271       --  the state to True.
1272
1273       if S.Waiting then
1274          S.Waiting := False;
1275          S.State := False;
1276
1277          Result := pthread_cond_signal (S.CV'Access);
1278          pragma Assert (Result = 0);
1279
1280       else
1281          S.State := True;
1282       end if;
1283
1284       Result := pthread_mutex_unlock (S.L'Access);
1285       pragma Assert (Result = 0);
1286
1287       SSL.Abort_Undefer.all;
1288    end Set_True;
1289
1290    ------------------------
1291    -- Suspend_Until_True --
1292    ------------------------
1293
1294    procedure Suspend_Until_True (S : in out Suspension_Object) is
1295       Result : Interfaces.C.int;
1296
1297    begin
1298       SSL.Abort_Defer.all;
1299
1300       Result := pthread_mutex_lock (S.L'Access);
1301       pragma Assert (Result = 0);
1302
1303       if S.Waiting then
1304
1305          --  Program_Error must be raised upon calling Suspend_Until_True
1306          --  if another task is already waiting on that suspension object
1307          --  (RM D.10(10)).
1308
1309          Result := pthread_mutex_unlock (S.L'Access);
1310          pragma Assert (Result = 0);
1311
1312          SSL.Abort_Undefer.all;
1313
1314          raise Program_Error;
1315
1316       else
1317          --  Suspend the task if the state is False. Otherwise, the task
1318          --  continues its execution, and the state of the suspension object
1319          --  is set to False (ARM D.10 par. 9).
1320
1321          if S.State then
1322             S.State := False;
1323          else
1324             S.Waiting := True;
1325
1326             loop
1327                --  Loop in case pthread_cond_wait returns earlier than expected
1328                --  (e.g. in case of EINTR caused by a signal).
1329
1330                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1331                pragma Assert (Result = 0 or else Result = EINTR);
1332
1333                exit when not S.Waiting;
1334             end loop;
1335          end if;
1336
1337          Result := pthread_mutex_unlock (S.L'Access);
1338          pragma Assert (Result = 0);
1339
1340          SSL.Abort_Undefer.all;
1341       end if;
1342    end Suspend_Until_True;
1343
1344    ----------------
1345    -- Check_Exit --
1346    ----------------
1347
1348    --  Dummy version
1349
1350    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1351       pragma Unreferenced (Self_ID);
1352    begin
1353       return True;
1354    end Check_Exit;
1355
1356    --------------------
1357    -- Check_No_Locks --
1358    --------------------
1359
1360    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1361       pragma Unreferenced (Self_ID);
1362    begin
1363       return True;
1364    end Check_No_Locks;
1365
1366    ----------------------
1367    -- Environment_Task --
1368    ----------------------
1369
1370    function Environment_Task return Task_Id is
1371    begin
1372       return Environment_Task_Id;
1373    end Environment_Task;
1374
1375    --------------
1376    -- Lock_RTS --
1377    --------------
1378
1379    procedure Lock_RTS is
1380    begin
1381       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1382    end Lock_RTS;
1383
1384    ----------------
1385    -- Unlock_RTS --
1386    ----------------
1387
1388    procedure Unlock_RTS is
1389    begin
1390       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1391    end Unlock_RTS;
1392
1393    ------------------
1394    -- Suspend_Task --
1395    ------------------
1396
1397    function Suspend_Task
1398      (T           : ST.Task_Id;
1399       Thread_Self : Thread_Id) return Boolean
1400    is
1401       pragma Unreferenced (T, Thread_Self);
1402    begin
1403       return False;
1404    end Suspend_Task;
1405
1406    -----------------
1407    -- Resume_Task --
1408    -----------------
1409
1410    function Resume_Task
1411      (T           : ST.Task_Id;
1412       Thread_Self : Thread_Id) return Boolean
1413    is
1414       pragma Unreferenced (T, Thread_Self);
1415    begin
1416       return False;
1417    end Resume_Task;
1418
1419    --------------------
1420    -- Stop_All_Tasks --
1421    --------------------
1422
1423    procedure Stop_All_Tasks is
1424    begin
1425       null;
1426    end Stop_All_Tasks;
1427
1428    ---------------
1429    -- Stop_Task --
1430    ---------------
1431
1432    function Stop_Task (T : ST.Task_Id) return Boolean is
1433       pragma Unreferenced (T);
1434    begin
1435       return False;
1436    end Stop_Task;
1437
1438    -------------------
1439    -- Continue_Task --
1440    -------------------
1441
1442    function Continue_Task (T : ST.Task_Id) return Boolean is
1443       pragma Unreferenced (T);
1444    begin
1445       return False;
1446    end Continue_Task;
1447
1448    ----------------
1449    -- Initialize --
1450    ----------------
1451
1452    procedure Initialize (Environment_Task : Task_Id) is
1453       act     : aliased struct_sigaction;
1454       old_act : aliased struct_sigaction;
1455       Tmp_Set : aliased sigset_t;
1456       Result  : Interfaces.C.int;
1457
1458       function State
1459         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1460       pragma Import (C, State, "__gnat_get_interrupt_state");
1461       --  Get interrupt state.  Defined in a-init.c
1462       --  The input argument is the interrupt number,
1463       --  and the result is one of the following:
1464
1465       Default : constant Character := 's';
1466       --    'n'   this interrupt not set by any Interrupt_State pragma
1467       --    'u'   Interrupt_State pragma set state to User
1468       --    'r'   Interrupt_State pragma set state to Runtime
1469       --    's'   Interrupt_State pragma set state to System (use "default"
1470       --           system handler)
1471
1472    begin
1473       Environment_Task_Id := Environment_Task;
1474
1475       Interrupt_Management.Initialize;
1476
1477       --  Prepare the set of signals that should unblocked in all tasks
1478
1479       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1480       pragma Assert (Result = 0);
1481
1482       for J in Interrupt_Management.Interrupt_ID loop
1483          if System.Interrupt_Management.Keep_Unmasked (J) then
1484             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1485             pragma Assert (Result = 0);
1486          end if;
1487       end loop;
1488
1489       --  Initialize the lock used to synchronize chain of all ATCBs
1490
1491       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1492
1493       Specific.Initialize (Environment_Task);
1494
1495       if Use_Alternate_Stack then
1496          Environment_Task.Common.Task_Alternate_Stack :=
1497            Alternate_Stack'Address;
1498       end if;
1499
1500       --  Make environment task known here because it doesn't go through
1501       --  Activate_Tasks, which does it for all other tasks.
1502
1503       Known_Tasks (Known_Tasks'First) := Environment_Task;
1504       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1505
1506       Enter_Task (Environment_Task);
1507
1508       if State
1509           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1510       then
1511          act.sa_flags := 0;
1512          act.sa_handler := Abort_Handler'Address;
1513
1514          Result := sigemptyset (Tmp_Set'Access);
1515          pragma Assert (Result = 0);
1516          act.sa_mask := Tmp_Set;
1517
1518          Result :=
1519            sigaction
1520              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1521               act'Unchecked_Access,
1522               old_act'Unchecked_Access);
1523          pragma Assert (Result = 0);
1524          Abort_Handler_Installed := True;
1525       end if;
1526    end Initialize;
1527
1528    -----------------------
1529    -- Set_Task_Affinity --
1530    -----------------------
1531
1532    procedure Set_Task_Affinity (T : ST.Task_Id) is
1533       pragma Unreferenced (T);
1534
1535    begin
1536       --  Setting task affinity is not supported by the underlying system
1537
1538       null;
1539    end Set_Task_Affinity;
1540
1541 end System.Task_Primitives.Operations;