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) 1992-2009, 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 with Ada.Unchecked_Deallocation;
  49
  50 with Interfaces.C;
  51
  52 with System.Tasking.Debug;
  53 with System.Interrupt_Management;
  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 SSL renames System.Soft_Links;
  66
  67    use System.Tasking.Debug;
  68    use System.Tasking;
  69    use Interfaces.C;
  70    use System.OS_Interface;
  71    use System.Parameters;
  72    use System.OS_Primitives;
  73
  74    Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
  75    --  Whether to use an alternate signal stack for stack overflows
  76
  77    ----------------
  78    -- Local Data --
  79    ----------------
  80
  81    --  The followings are logically constants, but need to be initialized
  82    --  at run time.
  83
  84    Single_RTS_Lock : aliased RTS_Lock;
  85    --  This is a lock to allow only one thread of control in the RTS at
  86    --  a time; it is used to execute in mutual exclusion from all other tasks.
  87    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  88
  89    ATCB_Key : aliased pthread_key_t;
  90    --  Key used to find the Ada Task_Id associated with a thread
  91
  92    Environment_Task_Id : Task_Id;
  93    --  A variable to hold Task_Id for the environment task
  94
  95    Locking_Policy : Character;
  96    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  97    --  Value of the pragma Locking_Policy:
  98    --    'C' for Ceiling_Locking
  99    --    'I' for Inherit_Locking
 100    --    ' ' for none.
 101
 102    Unblocked_Signal_Mask : aliased sigset_t;
 103    --  The set of signals that should unblocked in all tasks
 104
 105    --  The followings are internal configuration constants needed
 106
 107    Next_Serial_Number : Task_Serial_Number := 100;
 108    --  We start at 100, to reserve some special values for
 109    --  using in error checking.
 110
 111    Time_Slice_Val : Integer;
 112    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 113
 114    Dispatching_Policy : Character;
 115    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 116
 117    Foreign_Task_Elaborated : aliased Boolean := True;
 118    --  Used to identified fake tasks (i.e., non-Ada Threads)
 119
 120    --------------------
 121    -- Local Packages --
 122    --------------------
 123
 124    package Specific is
 125
 126       procedure Initialize (Environment_Task : Task_Id);
 127       pragma Inline (Initialize);
 128       --  Initialize various data needed by this package
 129
 130       function Is_Valid_Task return Boolean;
 131       pragma Inline (Is_Valid_Task);
 132       --  Does executing thread have a TCB?
 133
 134       procedure Set (Self_Id : Task_Id);
 135       pragma Inline (Set);
 136       --  Set the self id for the current task
 137
 138       function Self return Task_Id;
 139       pragma Inline (Self);
 140       --  Return a pointer to the Ada Task Control Block of the calling task
 141
 142    end Specific;
 143
 144    package body Specific is separate;
 145    --  The body of this package is target specific
 146
 147    ---------------------------------
 148    -- Support for foreign threads --
 149    ---------------------------------
 150
 151    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 152    --  Allocate and Initialize a new ATCB for the current Thread
 153
 154    function Register_Foreign_Thread
 155      (Thread : Thread_Id) return Task_Id is separate;
 156
 157    -----------------------
 158    -- Local Subprograms --
 159    -----------------------
 160
 161    procedure Abort_Handler (Sig : Signal);
 162    --  Signal handler used to implement asynchronous abort.
 163    --  See also comment before body, below.
 164
 165    function To_Address is
 166      new Ada.Unchecked_Conversion (Task_Id, System.Address);
 167
 168    -------------------
 169    -- Abort_Handler --
 170    -------------------
 171
 172    --  Target-dependent binding of inter-thread Abort signal to the raising of
 173    --  the Abort_Signal exception.
 174
 175    --  The technical issues and alternatives here are essentially the
 176    --  same as for raising exceptions in response to other signals
 177    --  (e.g. Storage_Error). See code and comments in the package body
 178    --  System.Interrupt_Management.
 179
 180    --  Some implementations may not allow an exception to be propagated out of
 181    --  a handler, and others might leave the signal or interrupt that invoked
 182    --  this handler masked after the exceptional return to the application
 183    --  code.
 184
 185    --  GNAT exceptions are originally implemented using setjmp()/longjmp(). On
 186    --  most UNIX systems, this will allow transfer out of a signal handler,
 187    --  which is usually the only mechanism available for implementing
 188    --  asynchronous handlers of this kind. However, some systems do not
 189    --  restore the signal mask on longjmp(), leaving the abort signal masked.
 190
 191    procedure Abort_Handler (Sig : Signal) is
 192       pragma Unreferenced (Sig);
 193
 194       T       : constant Task_Id := Self;
 195       Old_Set : aliased sigset_t;
 196
 197       Result : Interfaces.C.int;
 198       pragma Warnings (Off, Result);
 199
 200    begin
 201       --  It is not safe to raise an exception when using ZCX and the GCC
 202       --  exception handling mechanism.
 203
 204       if ZCX_By_Default and then GCC_ZCX_Support then
 205          return;
 206       end if;
 207
 208       if T.Deferral_Level = 0
 209         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 210         not T.Aborting
 211       then
 212          T.Aborting := True;
 213
 214          --  Make sure signals used for RTS internal purpose are unmasked
 215
 216          Result := pthread_sigmask (SIG_UNBLOCK,
 217            Unblocked_Signal_Mask'Access, Old_Set'Access);
 218          pragma Assert (Result = 0);
 219
 220          raise Standard'Abort_Signal;
 221       end if;
 222    end Abort_Handler;
 223
 224    -----------------
 225    -- Stack_Guard --
 226    -----------------
 227
 228    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 229       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 230       Guard_Page_Address : Address;
 231
 232       Res : Interfaces.C.int;
 233
 234    begin
 235       if Stack_Base_Available then
 236
 237          --  Compute the guard page address
 238
 239          Guard_Page_Address :=
 240            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 241
 242          if On then
 243             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_ON);
 244          else
 245             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_OFF);
 246          end if;
 247
 248          pragma Assert (Res = 0);
 249       end if;
 250    end Stack_Guard;
 251
 252    --------------------
 253    -- Get_Thread_Id  --
 254    --------------------
 255
 256    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 257    begin
 258       return T.Common.LL.Thread;
 259    end Get_Thread_Id;
 260
 261    ----------
 262    -- Self --
 263    ----------
 264
 265    function Self return Task_Id renames Specific.Self;
 266
 267    ---------------------
 268    -- Initialize_Lock --
 269    ---------------------
 270
 271    --  Note: mutexes and cond_variables needed per-task basis are
 272    --        initialized in Initialize_TCB and the Storage_Error is
 273    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 274    --        used in RTS is initialized before any status change of RTS.
 275    --        Therefore raising Storage_Error in the following routines
 276    --        should be able to be handled safely.
 277
 278    procedure Initialize_Lock
 279      (Prio : System.Any_Priority;
 280       L    : not null access Lock)
 281    is
 282       Attributes : aliased pthread_mutexattr_t;
 283       Result : Interfaces.C.int;
 284
 285    begin
 286       Result := pthread_mutexattr_init (Attributes'Access);
 287       pragma Assert (Result = 0 or else Result = ENOMEM);
 288
 289       if Result = ENOMEM then
 290          raise Storage_Error;
 291       end if;
 292
 293       if Locking_Policy = 'C' then
 294          Result := pthread_mutexattr_setprotocol
 295            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 296          pragma Assert (Result = 0);
 297
 298          Result := pthread_mutexattr_setprioceiling
 299             (Attributes'Access, Interfaces.C.int (Prio));
 300          pragma Assert (Result = 0);
 301
 302       elsif Locking_Policy = 'I' then
 303          Result := pthread_mutexattr_setprotocol
 304            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 305          pragma Assert (Result = 0);
 306       end if;
 307
 308       Result := pthread_mutex_init (L, Attributes'Access);
 309       pragma Assert (Result = 0 or else Result = ENOMEM);
 310
 311       if Result = ENOMEM then
 312          Result := pthread_mutexattr_destroy (Attributes'Access);
 313          raise Storage_Error;
 314       end if;
 315
 316       Result := pthread_mutexattr_destroy (Attributes'Access);
 317       pragma Assert (Result = 0);
 318    end Initialize_Lock;
 319
 320    procedure Initialize_Lock
 321      (L : not null access RTS_Lock; Level : Lock_Level)
 322    is
 323       pragma Unreferenced (Level);
 324
 325       Attributes : aliased pthread_mutexattr_t;
 326       Result     : Interfaces.C.int;
 327
 328    begin
 329       Result := pthread_mutexattr_init (Attributes'Access);
 330       pragma Assert (Result = 0 or else Result = ENOMEM);
 331
 332       if Result = ENOMEM then
 333          raise Storage_Error;
 334       end if;
 335
 336       if Locking_Policy = 'C' then
 337          Result := pthread_mutexattr_setprotocol
 338            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 339          pragma Assert (Result = 0);
 340
 341          Result := pthread_mutexattr_setprioceiling
 342             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 343          pragma Assert (Result = 0);
 344
 345       elsif Locking_Policy = 'I' then
 346          Result := pthread_mutexattr_setprotocol
 347            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 348          pragma Assert (Result = 0);
 349       end if;
 350
 351       Result := pthread_mutex_init (L, Attributes'Access);
 352       pragma Assert (Result = 0 or else Result = ENOMEM);
 353
 354       if Result = ENOMEM then
 355          Result := pthread_mutexattr_destroy (Attributes'Access);
 356          raise Storage_Error;
 357       end if;
 358
 359       Result := pthread_mutexattr_destroy (Attributes'Access);
 360       pragma Assert (Result = 0);
 361    end Initialize_Lock;
 362
 363    -------------------
 364    -- Finalize_Lock --
 365    -------------------
 366
 367    procedure Finalize_Lock (L : not null access Lock) is
 368       Result : Interfaces.C.int;
 369    begin
 370       Result := pthread_mutex_destroy (L);
 371       pragma Assert (Result = 0);
 372    end Finalize_Lock;
 373
 374    procedure Finalize_Lock (L : not null access RTS_Lock) is
 375       Result : Interfaces.C.int;
 376    begin
 377       Result := pthread_mutex_destroy (L);
 378       pragma Assert (Result = 0);
 379    end Finalize_Lock;
 380
 381    ----------------
 382    -- Write_Lock --
 383    ----------------
 384
 385    procedure Write_Lock
 386      (L : not null access Lock; Ceiling_Violation : out Boolean)
 387    is
 388       Result : Interfaces.C.int;
 389
 390    begin
 391       Result := pthread_mutex_lock (L);
 392
 393       --  Assume that the cause of EINVAL is a priority ceiling violation
 394
 395       Ceiling_Violation := (Result = EINVAL);
 396       pragma Assert (Result = 0 or else Result = EINVAL);
 397    end Write_Lock;
 398
 399    procedure Write_Lock
 400      (L           : not null access RTS_Lock;
 401       Global_Lock : Boolean := False)
 402    is
 403       Result : Interfaces.C.int;
 404    begin
 405       if not Single_Lock or else Global_Lock then
 406          Result := pthread_mutex_lock (L);
 407          pragma Assert (Result = 0);
 408       end if;
 409    end Write_Lock;
 410
 411    procedure Write_Lock (T : Task_Id) is
 412       Result : Interfaces.C.int;
 413    begin
 414       if not Single_Lock then
 415          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 416          pragma Assert (Result = 0);
 417       end if;
 418    end Write_Lock;
 419
 420    ---------------
 421    -- Read_Lock --
 422    ---------------
 423
 424    procedure Read_Lock
 425      (L : not null access Lock; Ceiling_Violation : out Boolean) is
 426    begin
 427       Write_Lock (L, Ceiling_Violation);
 428    end Read_Lock;
 429
 430    ------------
 431    -- Unlock --
 432    ------------
 433
 434    procedure Unlock (L : not null access Lock) is
 435       Result : Interfaces.C.int;
 436    begin
 437       Result := pthread_mutex_unlock (L);
 438       pragma Assert (Result = 0);
 439    end Unlock;
 440
 441    procedure Unlock
 442      (L : not null access RTS_Lock; Global_Lock : Boolean := False)
 443    is
 444       Result : Interfaces.C.int;
 445    begin
 446       if not Single_Lock or else Global_Lock then
 447          Result := pthread_mutex_unlock (L);
 448          pragma Assert (Result = 0);
 449       end if;
 450    end Unlock;
 451
 452    procedure Unlock (T : Task_Id) is
 453       Result : Interfaces.C.int;
 454    begin
 455       if not Single_Lock then
 456          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 457          pragma Assert (Result = 0);
 458       end if;
 459    end Unlock;
 460
 461    -----------------
 462    -- Set_Ceiling --
 463    -----------------
 464
 465    --  Dynamic priority ceilings are not supported by the underlying system
 466
 467    procedure Set_Ceiling
 468      (L    : not null access Lock;
 469       Prio : System.Any_Priority)
 470    is
 471       pragma Unreferenced (L, Prio);
 472    begin
 473       null;
 474    end Set_Ceiling;
 475
 476    -----------
 477    -- Sleep --
 478    -----------
 479
 480    procedure Sleep
 481      (Self_ID : Task_Id;
 482       Reason  : System.Tasking.Task_States)
 483    is
 484       pragma Unreferenced (Reason);
 485
 486       Result : Interfaces.C.int;
 487
 488    begin
 489       if Single_Lock then
 490          Result :=
 491            pthread_cond_wait
 492              (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 493       else
 494          Result :=
 495            pthread_cond_wait
 496              (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 497       end if;
 498
 499       --  EINTR is not considered a failure
 500
 501       pragma Assert (Result = 0 or else Result = EINTR);
 502    end Sleep;
 503
 504    -----------------
 505    -- Timed_Sleep --
 506    -----------------
 507
 508    --  This is for use within the run-time system, so abort is
 509    --  assumed to be already deferred, and the caller should be
 510    --  holding its own ATCB lock.
 511
 512    procedure Timed_Sleep
 513      (Self_ID  : Task_Id;
 514       Time     : Duration;
 515       Mode     : ST.Delay_Modes;
 516       Reason   : Task_States;
 517       Timedout : out Boolean;
 518       Yielded  : out Boolean)
 519    is
 520       pragma Unreferenced (Reason);
 521
 522       Base_Time  : constant Duration := Monotonic_Clock;
 523       Check_Time : Duration := Base_Time;
 524       Rel_Time   : Duration;
 525       Abs_Time   : Duration;
 526       Request    : aliased timespec;
 527       Result     : Interfaces.C.int;
 528
 529    begin
 530       Timedout := True;
 531       Yielded := False;
 532
 533       if Mode = Relative then
 534          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 535
 536          if Relative_Timed_Wait then
 537             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 538          end if;
 539
 540       else
 541          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 542
 543          if Relative_Timed_Wait then
 544             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 545          end if;
 546       end if;
 547
 548       if Abs_Time > Check_Time then
 549          if Relative_Timed_Wait then
 550             Request := To_Timespec (Rel_Time);
 551          else
 552             Request := To_Timespec (Abs_Time);
 553          end if;
 554
 555          loop
 556             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 557
 558             if Single_Lock then
 559                Result :=
 560                  pthread_cond_timedwait
 561                    (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 562                     Request'Access);
 563
 564             else
 565                Result :=
 566                  pthread_cond_timedwait
 567                    (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 568                     Request'Access);
 569             end if;
 570
 571             Check_Time := Monotonic_Clock;
 572             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 573
 574             if Result = 0 or Result = EINTR then
 575
 576                --  Somebody may have called Wakeup for us
 577
 578                Timedout := False;
 579                exit;
 580             end if;
 581
 582             pragma Assert (Result = ETIMEDOUT);
 583          end loop;
 584       end if;
 585    end Timed_Sleep;
 586
 587    -----------------
 588    -- Timed_Delay --
 589    -----------------
 590
 591    --  This is for use in implementing delay statements, so we assume the
 592    --  caller is abort-deferred but is holding no locks.
 593
 594    procedure Timed_Delay
 595      (Self_ID : Task_Id;
 596       Time    : Duration;
 597       Mode    : ST.Delay_Modes)
 598    is
 599       Base_Time  : constant Duration := Monotonic_Clock;
 600       Check_Time : Duration := Base_Time;
 601       Abs_Time   : Duration;
 602       Rel_Time   : Duration;
 603       Request    : aliased timespec;
 604
 605       Result : Interfaces.C.int;
 606       pragma Warnings (Off, Result);
 607
 608    begin
 609       if Single_Lock then
 610          Lock_RTS;
 611       end if;
 612
 613       Write_Lock (Self_ID);
 614
 615       if Mode = Relative then
 616          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 617
 618          if Relative_Timed_Wait then
 619             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 620          end if;
 621
 622       else
 623          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 624
 625          if Relative_Timed_Wait then
 626             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 627          end if;
 628       end if;
 629
 630       if Abs_Time > Check_Time then
 631          if Relative_Timed_Wait then
 632             Request := To_Timespec (Rel_Time);
 633          else
 634             Request := To_Timespec (Abs_Time);
 635          end if;
 636
 637          Self_ID.Common.State := Delay_Sleep;
 638
 639          loop
 640             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 641
 642             if Single_Lock then
 643                Result := pthread_cond_timedwait
 644                            (Self_ID.Common.LL.CV'Access,
 645                             Single_RTS_Lock'Access,
 646                             Request'Access);
 647             else
 648                Result := pthread_cond_timedwait
 649                            (Self_ID.Common.LL.CV'Access,
 650                             Self_ID.Common.LL.L'Access,
 651                             Request'Access);
 652             end if;
 653
 654             Check_Time := Monotonic_Clock;
 655             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 656
 657             pragma Assert (Result = 0
 658                              or else Result = ETIMEDOUT
 659                              or else Result = EINTR);
 660          end loop;
 661
 662          Self_ID.Common.State := Runnable;
 663       end if;
 664
 665       Unlock (Self_ID);
 666
 667       if Single_Lock then
 668          Unlock_RTS;
 669       end if;
 670
 671       Result := sched_yield;
 672    end Timed_Delay;
 673
 674    ---------------------
 675    -- Monotonic_Clock --
 676    ---------------------
 677
 678    function Monotonic_Clock return Duration is
 679       TS     : aliased timespec;
 680       Result : Interfaces.C.int;
 681    begin
 682       Result := clock_gettime
 683         (clock_id => CLOCK_REALTIME, tp => TS'Unchecked_Access);
 684       pragma Assert (Result = 0);
 685       return To_Duration (TS);
 686    end Monotonic_Clock;
 687
 688    -------------------
 689    -- RT_Resolution --
 690    -------------------
 691
 692    function RT_Resolution return Duration is
 693    begin
 694       return 10#1.0#E-6;
 695    end RT_Resolution;
 696
 697    ------------
 698    -- Wakeup --
 699    ------------
 700
 701    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 702       pragma Unreferenced (Reason);
 703       Result : Interfaces.C.int;
 704    begin
 705       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 706       pragma Assert (Result = 0);
 707    end Wakeup;
 708
 709    -----------
 710    -- Yield --
 711    -----------
 712
 713    procedure Yield (Do_Yield : Boolean := True) is
 714       Result : Interfaces.C.int;
 715       pragma Unreferenced (Result);
 716    begin
 717       if Do_Yield then
 718          Result := sched_yield;
 719       end if;
 720    end Yield;
 721
 722    ------------------
 723    -- Set_Priority --
 724    ------------------
 725
 726    procedure Set_Priority
 727      (T                   : Task_Id;
 728       Prio                : System.Any_Priority;
 729       Loss_Of_Inheritance : Boolean := False)
 730    is
 731       pragma Unreferenced (Loss_Of_Inheritance);
 732
 733       Result : Interfaces.C.int;
 734       Param  : aliased struct_sched_param;
 735
 736       function Get_Policy (Prio : System.Any_Priority) return Character;
 737       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 738       --  Get priority specific dispatching policy
 739
 740       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 741       --  Upper case first character of the policy name corresponding to the
 742       --  task as set by a Priority_Specific_Dispatching pragma.
 743
 744    begin
 745       T.Common.Current_Priority := Prio;
 746       Param.sched_priority := To_Target_Priority (Prio);
 747
 748       if Time_Slice_Supported
 749         and then (Dispatching_Policy = 'R'
 750                   or else Priority_Specific_Policy = 'R'
 751                   or else Time_Slice_Val > 0)
 752       then
 753          Result := pthread_setschedparam
 754            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 755
 756       elsif Dispatching_Policy = 'F'
 757         or else Priority_Specific_Policy = 'F'
 758         or else Time_Slice_Val = 0
 759       then
 760          Result := pthread_setschedparam
 761            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 762
 763       else
 764          Result := pthread_setschedparam
 765            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 766       end if;
 767
 768       pragma Assert (Result = 0);
 769    end Set_Priority;
 770
 771    ------------------
 772    -- Get_Priority --
 773    ------------------
 774
 775    function Get_Priority (T : Task_Id) return System.Any_Priority is
 776    begin
 777       return T.Common.Current_Priority;
 778    end Get_Priority;
 779
 780    ----------------
 781    -- Enter_Task --
 782    ----------------
 783
 784    procedure Enter_Task (Self_ID : Task_Id) is
 785    begin
 786       Self_ID.Common.LL.Thread := pthread_self;
 787       Self_ID.Common.LL.LWP := lwp_self;
 788
 789       Specific.Set (Self_ID);
 790
 791       if Use_Alternate_Stack then
 792          declare
 793             Stack  : aliased stack_t;
 794             Result : Interfaces.C.int;
 795          begin
 796             Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;
 797             Stack.ss_size  := Alternate_Stack_Size;
 798             Stack.ss_flags := 0;
 799             Result := sigaltstack (Stack'Access, null);
 800             pragma Assert (Result = 0);
 801          end;
 802       end if;
 803    end Enter_Task;
 804
 805    --------------
 806    -- New_ATCB --
 807    --------------
 808
 809    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 810    begin
 811       return new Ada_Task_Control_Block (Entry_Num);
 812    end New_ATCB;
 813
 814    -------------------
 815    -- Is_Valid_Task --
 816    -------------------
 817
 818    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 819
 820    -----------------------------
 821    -- Register_Foreign_Thread --
 822    -----------------------------
 823
 824    function Register_Foreign_Thread return Task_Id is
 825    begin
 826       if Is_Valid_Task then
 827          return Self;
 828       else
 829          return Register_Foreign_Thread (pthread_self);
 830       end if;
 831    end Register_Foreign_Thread;
 832
 833    --------------------
 834    -- Initialize_TCB --
 835    --------------------
 836
 837    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 838       Mutex_Attr : aliased pthread_mutexattr_t;
 839       Result     : Interfaces.C.int;
 840       Cond_Attr  : aliased pthread_condattr_t;
 841
 842    begin
 843       --  Give the task a unique serial number
 844
 845       Self_ID.Serial_Number := Next_Serial_Number;
 846       Next_Serial_Number := Next_Serial_Number + 1;
 847       pragma Assert (Next_Serial_Number /= 0);
 848
 849       if not Single_Lock then
 850          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 851          pragma Assert (Result = 0 or else Result = ENOMEM);
 852
 853          if Result = 0 then
 854             if Locking_Policy = 'C' then
 855                Result :=
 856                  pthread_mutexattr_setprotocol
 857                    (Mutex_Attr'Access,
 858                     PTHREAD_PRIO_PROTECT);
 859                pragma Assert (Result = 0);
 860
 861                Result :=
 862                  pthread_mutexattr_setprioceiling
 863                    (Mutex_Attr'Access,
 864                     Interfaces.C.int (System.Any_Priority'Last));
 865                pragma Assert (Result = 0);
 866
 867             elsif Locking_Policy = 'I' then
 868                Result :=
 869                  pthread_mutexattr_setprotocol
 870                    (Mutex_Attr'Access,
 871                     PTHREAD_PRIO_INHERIT);
 872                pragma Assert (Result = 0);
 873             end if;
 874
 875             Result :=
 876               pthread_mutex_init
 877                 (Self_ID.Common.LL.L'Access,
 878                  Mutex_Attr'Access);
 879             pragma Assert (Result = 0 or else Result = ENOMEM);
 880          end if;
 881
 882          if Result /= 0 then
 883             Succeeded := False;
 884             return;
 885          end if;
 886
 887          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 888          pragma Assert (Result = 0);
 889       end if;
 890
 891       Result := pthread_condattr_init (Cond_Attr'Access);
 892       pragma Assert (Result = 0 or else Result = ENOMEM);
 893
 894       if Result = 0 then
 895          Result :=
 896            pthread_cond_init
 897              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 898          pragma Assert (Result = 0 or else Result = ENOMEM);
 899       end if;
 900
 901       if Result = 0 then
 902          Succeeded := True;
 903       else
 904          if not Single_Lock then
 905             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 906             pragma Assert (Result = 0);
 907          end if;
 908
 909          Succeeded := False;
 910       end if;
 911
 912       Result := pthread_condattr_destroy (Cond_Attr'Access);
 913       pragma Assert (Result = 0);
 914    end Initialize_TCB;
 915
 916    -----------------
 917    -- Create_Task --
 918    -----------------
 919
 920    procedure Create_Task
 921      (T          : Task_Id;
 922       Wrapper    : System.Address;
 923       Stack_Size : System.Parameters.Size_Type;
 924       Priority   : System.Any_Priority;
 925       Succeeded  : out Boolean)
 926    is
 927       Attributes          : aliased pthread_attr_t;
 928       Adjusted_Stack_Size : Interfaces.C.size_t;
 929       Result              : Interfaces.C.int;
 930
 931       function Thread_Body_Access is new
 932         Ada.Unchecked_Conversion (System.Address, Thread_Body);
 933
 934       use System.Task_Info;
 935
 936    begin
 937       Adjusted_Stack_Size :=
 938          Interfaces.C.size_t (Stack_Size + Alternate_Stack_Size);
 939
 940       if Stack_Base_Available then
 941
 942          --  If Stack Checking is supported then allocate 2 additional pages:
 943
 944          --  In the worst case, stack is allocated at something like
 945          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 946          --  to be sure the effective stack size is greater than what
 947          --  has been asked.
 948
 949          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Get_Page_Size;
 950       end if;
 951
 952       Result := pthread_attr_init (Attributes'Access);
 953       pragma Assert (Result = 0 or else Result = ENOMEM);
 954
 955       if Result /= 0 then
 956          Succeeded := False;
 957          return;
 958       end if;
 959
 960       Result :=
 961         pthread_attr_setdetachstate
 962           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 963       pragma Assert (Result = 0);
 964
 965       Result :=
 966         pthread_attr_setstacksize
 967           (Attributes'Access, Adjusted_Stack_Size);
 968       pragma Assert (Result = 0);
 969
 970       if T.Common.Task_Info /= Default_Scope then
 971          case T.Common.Task_Info is
 972             when System.Task_Info.Process_Scope =>
 973                Result :=
 974                  pthread_attr_setscope
 975                    (Attributes'Access, PTHREAD_SCOPE_PROCESS);
 976
 977             when System.Task_Info.System_Scope =>
 978                Result :=
 979                  pthread_attr_setscope
 980                    (Attributes'Access, PTHREAD_SCOPE_SYSTEM);
 981
 982             when System.Task_Info.Default_Scope =>
 983                Result := 0;
 984          end case;
 985
 986          pragma Assert (Result = 0);
 987       end if;
 988
 989       --  Since the initial signal mask of a thread is inherited from the
 990       --  creator, and the Environment task has all its signals masked, we
 991       --  do not need to manipulate caller's signal mask at this point.
 992       --  All tasks in RTS will have All_Tasks_Mask initially.
 993
 994       Result := pthread_create
 995         (T.Common.LL.Thread'Access,
 996          Attributes'Access,
 997          Thread_Body_Access (Wrapper),
 998          To_Address (T));
 999       pragma Assert (Result = 0 or else Result = EAGAIN);
1000
1001       Succeeded := Result = 0;
1002
1003       Result := pthread_attr_destroy (Attributes'Access);
1004       pragma Assert (Result = 0);
1005
1006       if Succeeded then
1007          Set_Priority (T, Priority);
1008       end if;
1009    end Create_Task;
1010
1011    ------------------
1012    -- Finalize_TCB --
1013    ------------------
1014
1015    procedure Finalize_TCB (T : Task_Id) is
1016       Result  : Interfaces.C.int;
1017       Tmp     : Task_Id := T;
1018       Is_Self : constant Boolean := T = Self;
1019
1020       procedure Free is new
1021         Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
1022
1023    begin
1024       if not Single_Lock then
1025          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1026          pragma Assert (Result = 0);
1027       end if;
1028
1029       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1030       pragma Assert (Result = 0);
1031
1032       if T.Known_Tasks_Index /= -1 then
1033          Known_Tasks (T.Known_Tasks_Index) := null;
1034       end if;
1035
1036       Free (Tmp);
1037
1038       if Is_Self then
1039          Specific.Set (null);
1040       end if;
1041    end Finalize_TCB;
1042
1043    ---------------
1044    -- Exit_Task --
1045    ---------------
1046
1047    procedure Exit_Task is
1048    begin
1049       --  Mark this task as unknown, so that if Self is called, it won't
1050       --  return a dangling pointer.
1051
1052       Specific.Set (null);
1053    end Exit_Task;
1054
1055    ----------------
1056    -- Abort_Task --
1057    ----------------
1058
1059    procedure Abort_Task (T : Task_Id) is
1060       Result : Interfaces.C.int;
1061    begin
1062       Result :=
1063         pthread_kill
1064           (T.Common.LL.Thread,
1065            Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1066       pragma Assert (Result = 0);
1067    end Abort_Task;
1068
1069    ----------------
1070    -- Initialize --
1071    ----------------
1072
1073    procedure Initialize (S : in out Suspension_Object) is
1074       Mutex_Attr : aliased pthread_mutexattr_t;
1075       Cond_Attr  : aliased pthread_condattr_t;
1076       Result     : Interfaces.C.int;
1077
1078    begin
1079       --  Initialize internal state (always to False (RM D.10 (6)))
1080
1081       S.State := False;
1082       S.Waiting := False;
1083
1084       --  Initialize internal mutex
1085
1086       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1087       pragma Assert (Result = 0 or else Result = ENOMEM);
1088
1089       if Result = ENOMEM then
1090          raise Storage_Error;
1091       end if;
1092
1093       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1094       pragma Assert (Result = 0 or else Result = ENOMEM);
1095
1096       if Result = ENOMEM then
1097          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1098          pragma Assert (Result = 0);
1099
1100          raise Storage_Error;
1101       end if;
1102
1103       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1104       pragma Assert (Result = 0);
1105
1106       --  Initialize internal condition variable
1107
1108       Result := pthread_condattr_init (Cond_Attr'Access);
1109       pragma Assert (Result = 0 or else Result = ENOMEM);
1110
1111       if Result /= 0 then
1112          Result := pthread_mutex_destroy (S.L'Access);
1113          pragma Assert (Result = 0);
1114
1115          if Result = ENOMEM then
1116             raise Storage_Error;
1117          end if;
1118       end if;
1119
1120       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1121       pragma Assert (Result = 0 or else Result = ENOMEM);
1122
1123       if Result /= 0 then
1124          Result := pthread_mutex_destroy (S.L'Access);
1125          pragma Assert (Result = 0);
1126
1127          if Result = ENOMEM then
1128             Result := pthread_condattr_destroy (Cond_Attr'Access);
1129             pragma Assert (Result = 0);
1130             raise Storage_Error;
1131          end if;
1132       end if;
1133
1134       Result := pthread_condattr_destroy (Cond_Attr'Access);
1135       pragma Assert (Result = 0);
1136    end Initialize;
1137
1138    --------------
1139    -- Finalize --
1140    --------------
1141
1142    procedure Finalize (S : in out Suspension_Object) is
1143       Result : Interfaces.C.int;
1144
1145    begin
1146       --  Destroy internal mutex
1147
1148       Result := pthread_mutex_destroy (S.L'Access);
1149       pragma Assert (Result = 0);
1150
1151       --  Destroy internal condition variable
1152
1153       Result := pthread_cond_destroy (S.CV'Access);
1154       pragma Assert (Result = 0);
1155    end Finalize;
1156
1157    -------------------
1158    -- Current_State --
1159    -------------------
1160
1161    function Current_State (S : Suspension_Object) return Boolean is
1162    begin
1163       --  We do not want to use lock on this read operation. State is marked
1164       --  as Atomic so that we ensure that the value retrieved is correct.
1165
1166       return S.State;
1167    end Current_State;
1168
1169    ---------------
1170    -- Set_False --
1171    ---------------
1172
1173    procedure Set_False (S : in out Suspension_Object) is
1174       Result : Interfaces.C.int;
1175
1176    begin
1177       SSL.Abort_Defer.all;
1178
1179       Result := pthread_mutex_lock (S.L'Access);
1180       pragma Assert (Result = 0);
1181
1182       S.State := False;
1183
1184       Result := pthread_mutex_unlock (S.L'Access);
1185       pragma Assert (Result = 0);
1186
1187       SSL.Abort_Undefer.all;
1188    end Set_False;
1189
1190    --------------
1191    -- Set_True --
1192    --------------
1193
1194    procedure Set_True (S : in out Suspension_Object) is
1195       Result : Interfaces.C.int;
1196
1197    begin
1198       SSL.Abort_Defer.all;
1199
1200       Result := pthread_mutex_lock (S.L'Access);
1201       pragma Assert (Result = 0);
1202
1203       --  If there is already a task waiting on this suspension object then
1204       --  we resume it, leaving the state of the suspension object to False,
1205       --  as it is specified in (RM D.10(9)). Otherwise, it just leaves
1206       --  the state to True.
1207
1208       if S.Waiting then
1209          S.Waiting := False;
1210          S.State := False;
1211
1212          Result := pthread_cond_signal (S.CV'Access);
1213          pragma Assert (Result = 0);
1214
1215       else
1216          S.State := True;
1217       end if;
1218
1219       Result := pthread_mutex_unlock (S.L'Access);
1220       pragma Assert (Result = 0);
1221
1222       SSL.Abort_Undefer.all;
1223    end Set_True;
1224
1225    ------------------------
1226    -- Suspend_Until_True --
1227    ------------------------
1228
1229    procedure Suspend_Until_True (S : in out Suspension_Object) is
1230       Result : Interfaces.C.int;
1231
1232    begin
1233       SSL.Abort_Defer.all;
1234
1235       Result := pthread_mutex_lock (S.L'Access);
1236       pragma Assert (Result = 0);
1237
1238       if S.Waiting then
1239
1240          --  Program_Error must be raised upon calling Suspend_Until_True
1241          --  if another task is already waiting on that suspension object
1242          --  (RM D.10(10)).
1243
1244          Result := pthread_mutex_unlock (S.L'Access);
1245          pragma Assert (Result = 0);
1246
1247          SSL.Abort_Undefer.all;
1248
1249          raise Program_Error;
1250
1251       else
1252          --  Suspend the task if the state is False. Otherwise, the task
1253          --  continues its execution, and the state of the suspension object
1254          --  is set to False (ARM D.10 par. 9).
1255
1256          if S.State then
1257             S.State := False;
1258          else
1259             S.Waiting := True;
1260
1261             loop
1262                --  Loop in case pthread_cond_wait returns earlier than expected
1263                --  (e.g. in case of EINTR caused by a signal).
1264
1265                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1266                pragma Assert (Result = 0 or else Result = EINTR);
1267
1268                exit when not S.Waiting;
1269             end loop;
1270          end if;
1271
1272          Result := pthread_mutex_unlock (S.L'Access);
1273          pragma Assert (Result = 0);
1274
1275          SSL.Abort_Undefer.all;
1276       end if;
1277    end Suspend_Until_True;
1278
1279    ----------------
1280    -- Check_Exit --
1281    ----------------
1282
1283    --  Dummy version
1284
1285    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1286       pragma Unreferenced (Self_ID);
1287    begin
1288       return True;
1289    end Check_Exit;
1290
1291    --------------------
1292    -- Check_No_Locks --
1293    --------------------
1294
1295    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1296       pragma Unreferenced (Self_ID);
1297    begin
1298       return True;
1299    end Check_No_Locks;
1300
1301    ----------------------
1302    -- Environment_Task --
1303    ----------------------
1304
1305    function Environment_Task return Task_Id is
1306    begin
1307       return Environment_Task_Id;
1308    end Environment_Task;
1309
1310    --------------
1311    -- Lock_RTS --
1312    --------------
1313
1314    procedure Lock_RTS is
1315    begin
1316       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1317    end Lock_RTS;
1318
1319    ----------------
1320    -- Unlock_RTS --
1321    ----------------
1322
1323    procedure Unlock_RTS is
1324    begin
1325       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1326    end Unlock_RTS;
1327
1328    ------------------
1329    -- Suspend_Task --
1330    ------------------
1331
1332    function Suspend_Task
1333      (T           : ST.Task_Id;
1334       Thread_Self : Thread_Id) return Boolean
1335    is
1336       pragma Unreferenced (T, Thread_Self);
1337    begin
1338       return False;
1339    end Suspend_Task;
1340
1341    -----------------
1342    -- Resume_Task --
1343    -----------------
1344
1345    function Resume_Task
1346      (T           : ST.Task_Id;
1347       Thread_Self : Thread_Id) return Boolean
1348    is
1349       pragma Unreferenced (T, Thread_Self);
1350    begin
1351       return False;
1352    end Resume_Task;
1353
1354    --------------------
1355    -- Stop_All_Tasks --
1356    --------------------
1357
1358    procedure Stop_All_Tasks is
1359    begin
1360       null;
1361    end Stop_All_Tasks;
1362
1363    ---------------
1364    -- Stop_Task --
1365    ---------------
1366
1367    function Stop_Task (T : ST.Task_Id) return Boolean is
1368       pragma Unreferenced (T);
1369    begin
1370       return False;
1371    end Stop_Task;
1372
1373    -------------------
1374    -- Continue_Task --
1375    -------------------
1376
1377    function Continue_Task (T : ST.Task_Id) return Boolean is
1378       pragma Unreferenced (T);
1379    begin
1380       return False;
1381    end Continue_Task;
1382
1383    ----------------
1384    -- Initialize --
1385    ----------------
1386
1387    procedure Initialize (Environment_Task : Task_Id) is
1388       act     : aliased struct_sigaction;
1389       old_act : aliased struct_sigaction;
1390       Tmp_Set : aliased sigset_t;
1391       Result  : Interfaces.C.int;
1392
1393       function State
1394         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1395       pragma Import (C, State, "__gnat_get_interrupt_state");
1396       --  Get interrupt state.  Defined in a-init.c
1397       --  The input argument is the interrupt number,
1398       --  and the result is one of the following:
1399
1400       Default : constant Character := 's';
1401       --    'n'   this interrupt not set by any Interrupt_State pragma
1402       --    'u'   Interrupt_State pragma set state to User
1403       --    'r'   Interrupt_State pragma set state to Runtime
1404       --    's'   Interrupt_State pragma set state to System (use "default"
1405       --           system handler)
1406
1407    begin
1408       Environment_Task_Id := Environment_Task;
1409
1410       Interrupt_Management.Initialize;
1411
1412       --  Prepare the set of signals that should unblocked in all tasks
1413
1414       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1415       pragma Assert (Result = 0);
1416
1417       for J in Interrupt_Management.Interrupt_ID loop
1418          if System.Interrupt_Management.Keep_Unmasked (J) then
1419             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1420             pragma Assert (Result = 0);
1421          end if;
1422       end loop;
1423
1424       --  Initialize the lock used to synchronize chain of all ATCBs
1425
1426       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1427
1428       Specific.Initialize (Environment_Task);
1429
1430       if Use_Alternate_Stack then
1431          Environment_Task.Common.Task_Alternate_Stack :=
1432            Alternate_Stack'Address;
1433       end if;
1434
1435       --  Make environment task known here because it doesn't go through
1436       --  Activate_Tasks, which does it for all other tasks.
1437
1438       Known_Tasks (Known_Tasks'First) := Environment_Task;
1439       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1440
1441       Enter_Task (Environment_Task);
1442
1443       --  Install the abort-signal handler
1444
1445       if State
1446           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1447       then
1448          act.sa_flags := 0;
1449          act.sa_handler := Abort_Handler'Address;
1450
1451          Result := sigemptyset (Tmp_Set'Access);
1452          pragma Assert (Result = 0);
1453          act.sa_mask := Tmp_Set;
1454
1455          Result :=
1456            sigaction
1457              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1458               act'Unchecked_Access,
1459               old_act'Unchecked_Access);
1460          pragma Assert (Result = 0);
1461       end if;
1462    end Initialize;
1463
1464 end System.Task_Primitives.Operations;