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) 1992-2005, 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 2,  or (at your option) any later ver- --
  14 -- sion. GNARL 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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is a POSIX-like version of this package
  35
  36 --  This package contains all the GNULL primitives that interface directly
  37 --  with the underlying OS.
  38
  39 --  Note: this file can only be used for POSIX compliant systems that
  40 --  implement SCHED_FIFO and Ceiling Locking correctly.
  41
  42 --  For configurations where SCHED_FIFO and priority ceiling are not a
  43 --  requirement, this file can also be used (e.g AiX threads)
  44
  45 pragma Polling (Off);
  46 --  Turn off polling, we do not want ATC polling to take place during
  47 --  tasking operations. It causes infinite loops and other problems.
  48
  49 with System.Tasking.Debug;
  50 --  used for Known_Tasks
  51
  52 with System.Interrupt_Management;
  53 --  used for Keep_Unmasked
  54 --           Abort_Task_Interrupt
  55 --           Interrupt_ID
  56
  57 with System.OS_Primitives;
  58 --  used for Delay_Modes
  59
  60 with System.Task_Info;
  61 --  used for Task_Info_Type
  62
  63 with Interfaces.C;
  64 --  used for int
  65 --           size_t
  66
  67 with System.Parameters;
  68 --  used for Size_Type
  69
  70 with Unchecked_Conversion;
  71 with Unchecked_Deallocation;
  72
  73 package body System.Task_Primitives.Operations is
  74
  75    use System.Tasking.Debug;
  76    use System.Tasking;
  77    use Interfaces.C;
  78    use System.OS_Interface;
  79    use System.Parameters;
  80    use System.OS_Primitives;
  81
  82    ----------------
  83    -- Local Data --
  84    ----------------
  85
  86    --  The followings are logically constants, but need to be initialized
  87    --  at run time.
  88
  89    Single_RTS_Lock : aliased RTS_Lock;
  90    --  This is a lock to allow only one thread of control in the RTS at
  91    --  a time; it is used to execute in mutual exclusion from all other tasks.
  92    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  93
  94    ATCB_Key : aliased pthread_key_t;
  95    --  Key used to find the Ada Task_Id associated with a thread
  96
  97    Environment_Task_Id : Task_Id;
  98    --  A variable to hold Task_Id for the environment task.
  99
 100    Locking_Policy : Character;
 101    pragma Import (C, Locking_Policy, "__gl_locking_policy");
 102    --  Value of the pragma Locking_Policy:
 103    --    'C' for Ceiling_Locking
 104    --    'I' for Inherit_Locking
 105    --    ' ' for none.
 106
 107    Unblocked_Signal_Mask : aliased sigset_t;
 108    --  The set of signals that should unblocked in all tasks
 109
 110    --  The followings are internal configuration constants needed.
 111
 112    Next_Serial_Number : Task_Serial_Number := 100;
 113    --  We start at 100, to reserve some special values for
 114    --  using in error checking.
 115
 116    Time_Slice_Val : Integer;
 117    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 118
 119    Dispatching_Policy : Character;
 120    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 121
 122    Foreign_Task_Elaborated : aliased Boolean := True;
 123    --  Used to identified fake tasks (i.e., non-Ada Threads).
 124
 125    --------------------
 126    -- Local Packages --
 127    --------------------
 128
 129    package Specific is
 130
 131       procedure Initialize (Environment_Task : Task_Id);
 132       pragma Inline (Initialize);
 133       --  Initialize various data needed by this package.
 134
 135       function Is_Valid_Task return Boolean;
 136       pragma Inline (Is_Valid_Task);
 137       --  Does executing thread have a TCB?
 138
 139       procedure Set (Self_Id : Task_Id);
 140       pragma Inline (Set);
 141       --  Set the self id for the current task.
 142
 143       function Self return Task_Id;
 144       pragma Inline (Self);
 145       --  Return a pointer to the Ada Task Control Block of the calling task.
 146
 147    end Specific;
 148
 149    package body Specific is separate;
 150    --  The body of this package is target specific.
 151
 152    ---------------------------------
 153    -- Support for foreign threads --
 154    ---------------------------------
 155
 156    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 157    --  Allocate and Initialize a new ATCB for the current Thread.
 158
 159    function Register_Foreign_Thread
 160      (Thread : Thread_Id) return Task_Id is separate;
 161
 162    -----------------------
 163    -- Local Subprograms --
 164    -----------------------
 165
 166    procedure Abort_Handler (Sig : Signal);
 167    --  Signal handler used to implement asynchronous abort.
 168    --  See also comment before body, below.
 169
 170    function To_Address is new Unchecked_Conversion (Task_Id, System.Address);
 171
 172    -------------------
 173    -- Abort_Handler --
 174    -------------------
 175
 176    --  Target-dependent binding of inter-thread Abort signal to
 177    --  the raising of the Abort_Signal exception.
 178
 179    --  The technical issues and alternatives here are essentially
 180    --  the same as for raising exceptions in response to other
 181    --  signals (e.g. Storage_Error). See code and comments in
 182    --  the package body System.Interrupt_Management.
 183
 184    --  Some implementations may not allow an exception to be propagated
 185    --  out of a handler, and others might leave the signal or
 186    --  interrupt that invoked this handler masked after the exceptional
 187    --  return to the application code.
 188
 189    --  GNAT exceptions are originally implemented using setjmp()/longjmp().
 190    --  On most UNIX systems, this will allow transfer out of a signal handler,
 191    --  which is usually the only mechanism available for implementing
 192    --  asynchronous handlers of this kind. However, some
 193    --  systems do not restore the signal mask on longjmp(), leaving the
 194    --  abort signal masked.
 195
 196    procedure Abort_Handler (Sig : Signal) is
 197       pragma Warnings (Off, Sig);
 198
 199       T       : constant Task_Id := Self;
 200       Result  : Interfaces.C.int;
 201       Old_Set : aliased sigset_t;
 202
 203    begin
 204       --  It is not safe to raise an exception when using ZCX and the GCC
 205       --  exception handling mechanism.
 206
 207       if ZCX_By_Default and then GCC_ZCX_Support then
 208          return;
 209       end if;
 210
 211       if T.Deferral_Level = 0
 212         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 213         not T.Aborting
 214       then
 215          T.Aborting := True;
 216
 217          --  Make sure signals used for RTS internal purpose are unmasked
 218
 219          Result := pthread_sigmask (SIG_UNBLOCK,
 220            Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access);
 221          pragma Assert (Result = 0);
 222
 223          raise Standard'Abort_Signal;
 224       end if;
 225    end Abort_Handler;
 226
 227    -----------------
 228    -- Stack_Guard --
 229    -----------------
 230
 231    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 232       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 233       Guard_Page_Address : Address;
 234
 235       Res : Interfaces.C.int;
 236
 237    begin
 238       if Stack_Base_Available then
 239
 240          --  Compute the guard page address
 241
 242          Guard_Page_Address :=
 243            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 244
 245          if On then
 246             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_ON);
 247          else
 248             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_OFF);
 249          end if;
 250
 251          pragma Assert (Res = 0);
 252       end if;
 253    end Stack_Guard;
 254
 255    --------------------
 256    -- Get_Thread_Id  --
 257    --------------------
 258
 259    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 260    begin
 261       return T.Common.LL.Thread;
 262    end Get_Thread_Id;
 263
 264    ----------
 265    -- Self --
 266    ----------
 267
 268    function Self return Task_Id renames Specific.Self;
 269
 270    ---------------------
 271    -- Initialize_Lock --
 272    ---------------------
 273
 274    --  Note: mutexes and cond_variables needed per-task basis are
 275    --        initialized in Intialize_TCB and the Storage_Error is
 276    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 277    --        used in RTS is initialized before any status change of RTS.
 278    --        Therefore rasing Storage_Error in the following routines
 279    --        should be able to be handled safely.
 280
 281    procedure Initialize_Lock
 282      (Prio : System.Any_Priority;
 283       L    : access Lock)
 284    is
 285       Attributes : aliased pthread_mutexattr_t;
 286       Result : Interfaces.C.int;
 287
 288    begin
 289       Result := pthread_mutexattr_init (Attributes'Access);
 290       pragma Assert (Result = 0 or else Result = ENOMEM);
 291
 292       if Result = ENOMEM then
 293          raise Storage_Error;
 294       end if;
 295
 296       if Locking_Policy = 'C' then
 297          Result := pthread_mutexattr_setprotocol
 298            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 299          pragma Assert (Result = 0);
 300
 301          Result := pthread_mutexattr_setprioceiling
 302             (Attributes'Access, Interfaces.C.int (Prio));
 303          pragma Assert (Result = 0);
 304
 305       elsif Locking_Policy = 'I' then
 306          Result := pthread_mutexattr_setprotocol
 307            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 308          pragma Assert (Result = 0);
 309       end if;
 310
 311       Result := pthread_mutex_init (L, Attributes'Access);
 312       pragma Assert (Result = 0 or else Result = ENOMEM);
 313
 314       if Result = ENOMEM then
 315          Result := pthread_mutexattr_destroy (Attributes'Access);
 316          raise Storage_Error;
 317       end if;
 318
 319       Result := pthread_mutexattr_destroy (Attributes'Access);
 320       pragma Assert (Result = 0);
 321    end Initialize_Lock;
 322
 323    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 324       pragma Warnings (Off, Level);
 325
 326       Attributes : aliased pthread_mutexattr_t;
 327       Result     : Interfaces.C.int;
 328
 329    begin
 330       Result := pthread_mutexattr_init (Attributes'Access);
 331       pragma Assert (Result = 0 or else Result = ENOMEM);
 332
 333       if Result = ENOMEM then
 334          raise Storage_Error;
 335       end if;
 336
 337       if Locking_Policy = 'C' then
 338          Result := pthread_mutexattr_setprotocol
 339            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 340          pragma Assert (Result = 0);
 341
 342          Result := pthread_mutexattr_setprioceiling
 343             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 344          pragma Assert (Result = 0);
 345
 346       elsif Locking_Policy = 'I' then
 347          Result := pthread_mutexattr_setprotocol
 348            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 349          pragma Assert (Result = 0);
 350       end if;
 351
 352       Result := pthread_mutex_init (L, Attributes'Access);
 353       pragma Assert (Result = 0 or else Result = ENOMEM);
 354
 355       if Result = ENOMEM then
 356          Result := pthread_mutexattr_destroy (Attributes'Access);
 357          raise Storage_Error;
 358       end if;
 359
 360       Result := pthread_mutexattr_destroy (Attributes'Access);
 361       pragma Assert (Result = 0);
 362    end Initialize_Lock;
 363
 364    -------------------
 365    -- Finalize_Lock --
 366    -------------------
 367
 368    procedure Finalize_Lock (L : access Lock) is
 369       Result : Interfaces.C.int;
 370
 371    begin
 372       Result := pthread_mutex_destroy (L);
 373       pragma Assert (Result = 0);
 374    end Finalize_Lock;
 375
 376    procedure Finalize_Lock (L : access RTS_Lock) is
 377       Result : Interfaces.C.int;
 378
 379    begin
 380       Result := pthread_mutex_destroy (L);
 381       pragma Assert (Result = 0);
 382    end Finalize_Lock;
 383
 384    ----------------
 385    -- Write_Lock --
 386    ----------------
 387
 388    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 389       Result : Interfaces.C.int;
 390
 391    begin
 392       Result := pthread_mutex_lock (L);
 393
 394       --  Assume that the cause of EINVAL is a priority ceiling violation
 395
 396       Ceiling_Violation := (Result = EINVAL);
 397       pragma Assert (Result = 0 or else Result = EINVAL);
 398    end Write_Lock;
 399
 400    procedure Write_Lock
 401      (L           : access RTS_Lock;
 402       Global_Lock : Boolean := False)
 403    is
 404       Result : Interfaces.C.int;
 405
 406    begin
 407       if not Single_Lock or else Global_Lock then
 408          Result := pthread_mutex_lock (L);
 409          pragma Assert (Result = 0);
 410       end if;
 411    end Write_Lock;
 412
 413    procedure Write_Lock (T : Task_Id) is
 414       Result : Interfaces.C.int;
 415
 416    begin
 417       if not Single_Lock then
 418          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 419          pragma Assert (Result = 0);
 420       end if;
 421    end Write_Lock;
 422
 423    ---------------
 424    -- Read_Lock --
 425    ---------------
 426
 427    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 428    begin
 429       Write_Lock (L, Ceiling_Violation);
 430    end Read_Lock;
 431
 432    ------------
 433    -- Unlock --
 434    ------------
 435
 436    procedure Unlock (L : access Lock) is
 437       Result : Interfaces.C.int;
 438
 439    begin
 440       Result := pthread_mutex_unlock (L);
 441       pragma Assert (Result = 0);
 442    end Unlock;
 443
 444    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 445       Result : Interfaces.C.int;
 446
 447    begin
 448       if not Single_Lock or else Global_Lock then
 449          Result := pthread_mutex_unlock (L);
 450          pragma Assert (Result = 0);
 451       end if;
 452    end Unlock;
 453
 454    procedure Unlock (T : Task_Id) is
 455       Result : Interfaces.C.int;
 456
 457    begin
 458       if not Single_Lock then
 459          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 460          pragma Assert (Result = 0);
 461       end if;
 462    end Unlock;
 463
 464    -----------
 465    -- Sleep --
 466    -----------
 467
 468    procedure Sleep
 469      (Self_ID : Task_Id;
 470       Reason   : System.Tasking.Task_States)
 471    is
 472       pragma Warnings (Off, Reason);
 473
 474       Result : Interfaces.C.int;
 475
 476    begin
 477       if Single_Lock then
 478          Result := pthread_cond_wait
 479            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 480       else
 481          Result := pthread_cond_wait
 482            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 483       end if;
 484
 485       --  EINTR is not considered a failure.
 486
 487       pragma Assert (Result = 0 or else Result = EINTR);
 488    end Sleep;
 489
 490    -----------------
 491    -- Timed_Sleep --
 492    -----------------
 493
 494    --  This is for use within the run-time system, so abort is
 495    --  assumed to be already deferred, and the caller should be
 496    --  holding its own ATCB lock.
 497
 498    procedure Timed_Sleep
 499      (Self_ID  : Task_Id;
 500       Time     : Duration;
 501       Mode     : ST.Delay_Modes;
 502       Reason   : Task_States;
 503       Timedout : out Boolean;
 504       Yielded  : out Boolean)
 505    is
 506       pragma Warnings (Off, Reason);
 507
 508       Check_Time : constant Duration := Monotonic_Clock;
 509       Rel_Time   : Duration;
 510       Abs_Time   : Duration;
 511       Request    : aliased timespec;
 512       Result     : Interfaces.C.int;
 513
 514    begin
 515       Timedout := True;
 516       Yielded := False;
 517
 518       if Mode = Relative then
 519          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 520
 521          if Relative_Timed_Wait then
 522             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 523          end if;
 524
 525       else
 526          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 527
 528          if Relative_Timed_Wait then
 529             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 530          end if;
 531       end if;
 532
 533       if Abs_Time > Check_Time then
 534          if Relative_Timed_Wait then
 535             Request := To_Timespec (Rel_Time);
 536          else
 537             Request := To_Timespec (Abs_Time);
 538          end if;
 539
 540          loop
 541             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 542               or else Self_ID.Pending_Priority_Change;
 543
 544             if Single_Lock then
 545                Result := pthread_cond_timedwait
 546                  (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 547                   Request'Access);
 548
 549             else
 550                Result := pthread_cond_timedwait
 551                  (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 552                   Request'Access);
 553             end if;
 554
 555             exit when Abs_Time <= Monotonic_Clock;
 556
 557             if Result = 0 or Result = EINTR then
 558
 559                --  Somebody may have called Wakeup for us
 560
 561                Timedout := False;
 562                exit;
 563             end if;
 564
 565             pragma Assert (Result = ETIMEDOUT);
 566          end loop;
 567       end if;
 568    end Timed_Sleep;
 569
 570    -----------------
 571    -- Timed_Delay --
 572    -----------------
 573
 574    --  This is for use in implementing delay statements, so
 575    --  we assume the caller is abort-deferred but is holding
 576    --  no locks.
 577
 578    procedure Timed_Delay
 579      (Self_ID  : Task_Id;
 580       Time     : Duration;
 581       Mode     : ST.Delay_Modes)
 582    is
 583       Check_Time : constant Duration := Monotonic_Clock;
 584       Abs_Time   : Duration;
 585       Rel_Time   : Duration;
 586       Request    : aliased timespec;
 587       Result     : Interfaces.C.int;
 588
 589    begin
 590       if Single_Lock then
 591          Lock_RTS;
 592       end if;
 593
 594       Write_Lock (Self_ID);
 595
 596       if Mode = Relative then
 597          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 598
 599          if Relative_Timed_Wait then
 600             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 601          end if;
 602
 603       else
 604          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 605
 606          if Relative_Timed_Wait then
 607             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 608          end if;
 609       end if;
 610
 611       if Abs_Time > Check_Time then
 612          if Relative_Timed_Wait then
 613             Request := To_Timespec (Rel_Time);
 614          else
 615             Request := To_Timespec (Abs_Time);
 616          end if;
 617
 618          Self_ID.Common.State := Delay_Sleep;
 619
 620          loop
 621             if Self_ID.Pending_Priority_Change then
 622                Self_ID.Pending_Priority_Change := False;
 623                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 624                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 625             end if;
 626
 627             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 628
 629             if Single_Lock then
 630                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 631                  Single_RTS_Lock'Access, Request'Access);
 632             else
 633                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 634                  Self_ID.Common.LL.L'Access, Request'Access);
 635             end if;
 636
 637             exit when Abs_Time <= Monotonic_Clock;
 638
 639             pragma Assert (Result = 0
 640                              or else Result = ETIMEDOUT
 641                              or else Result = EINTR);
 642          end loop;
 643
 644          Self_ID.Common.State := Runnable;
 645       end if;
 646
 647       Unlock (Self_ID);
 648
 649       if Single_Lock then
 650          Unlock_RTS;
 651       end if;
 652
 653       Result := sched_yield;
 654    end Timed_Delay;
 655
 656    ---------------------
 657    -- Monotonic_Clock --
 658    ---------------------
 659
 660    function Monotonic_Clock return Duration is
 661       TS     : aliased timespec;
 662       Result : Interfaces.C.int;
 663    begin
 664       Result := clock_gettime
 665         (clock_id => CLOCK_REALTIME, tp => TS'Unchecked_Access);
 666       pragma Assert (Result = 0);
 667       return To_Duration (TS);
 668    end Monotonic_Clock;
 669
 670    -------------------
 671    -- RT_Resolution --
 672    -------------------
 673
 674    function RT_Resolution return Duration is
 675    begin
 676       return 10#1.0#E-6;
 677    end RT_Resolution;
 678
 679    ------------
 680    -- Wakeup --
 681    ------------
 682
 683    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 684       pragma Warnings (Off, Reason);
 685       Result : Interfaces.C.int;
 686    begin
 687       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 688       pragma Assert (Result = 0);
 689    end Wakeup;
 690
 691    -----------
 692    -- Yield --
 693    -----------
 694
 695    procedure Yield (Do_Yield : Boolean := True) is
 696       Result : Interfaces.C.int;
 697       pragma Unreferenced (Result);
 698    begin
 699       if Do_Yield then
 700          Result := sched_yield;
 701       end if;
 702    end Yield;
 703
 704    ------------------
 705    -- Set_Priority --
 706    ------------------
 707
 708    procedure Set_Priority
 709      (T                   : Task_Id;
 710       Prio                : System.Any_Priority;
 711       Loss_Of_Inheritance : Boolean := False)
 712    is
 713       pragma Warnings (Off, Loss_Of_Inheritance);
 714
 715       Result : Interfaces.C.int;
 716       Param  : aliased struct_sched_param;
 717
 718    begin
 719       T.Common.Current_Priority := Prio;
 720       Param.sched_priority := Interfaces.C.int (Prio);
 721
 722       if Time_Slice_Supported and then Time_Slice_Val > 0 then
 723          Result := pthread_setschedparam
 724            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 725
 726       elsif Dispatching_Policy = 'F' or else Time_Slice_Val = 0 then
 727          Result := pthread_setschedparam
 728            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 729
 730       else
 731          Result := pthread_setschedparam
 732            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 733       end if;
 734
 735       pragma Assert (Result = 0);
 736    end Set_Priority;
 737
 738    ------------------
 739    -- Get_Priority --
 740    ------------------
 741
 742    function Get_Priority (T : Task_Id) return System.Any_Priority is
 743    begin
 744       return T.Common.Current_Priority;
 745    end Get_Priority;
 746
 747    ----------------
 748    -- Enter_Task --
 749    ----------------
 750
 751    procedure Enter_Task (Self_ID : Task_Id) is
 752    begin
 753       Self_ID.Common.LL.Thread := pthread_self;
 754       Self_ID.Common.LL.LWP := lwp_self;
 755
 756       Specific.Set (Self_ID);
 757
 758       Lock_RTS;
 759
 760       for J in Known_Tasks'Range loop
 761          if Known_Tasks (J) = null then
 762             Known_Tasks (J) := Self_ID;
 763             Self_ID.Known_Tasks_Index := J;
 764             exit;
 765          end if;
 766       end loop;
 767
 768       Unlock_RTS;
 769    end Enter_Task;
 770
 771    --------------
 772    -- New_ATCB --
 773    --------------
 774
 775    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 776    begin
 777       return new Ada_Task_Control_Block (Entry_Num);
 778    end New_ATCB;
 779
 780    -------------------
 781    -- Is_Valid_Task --
 782    -------------------
 783
 784    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 785
 786    -----------------------------
 787    -- Register_Foreign_Thread --
 788    -----------------------------
 789
 790    function Register_Foreign_Thread return Task_Id is
 791    begin
 792       if Is_Valid_Task then
 793          return Self;
 794       else
 795          return Register_Foreign_Thread (pthread_self);
 796       end if;
 797    end Register_Foreign_Thread;
 798
 799    --------------------
 800    -- Initialize_TCB --
 801    --------------------
 802
 803    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 804       Mutex_Attr : aliased pthread_mutexattr_t;
 805       Result     : Interfaces.C.int;
 806       Cond_Attr  : aliased pthread_condattr_t;
 807
 808    begin
 809       --  Give the task a unique serial number.
 810
 811       Self_ID.Serial_Number := Next_Serial_Number;
 812       Next_Serial_Number := Next_Serial_Number + 1;
 813       pragma Assert (Next_Serial_Number /= 0);
 814
 815       if not Single_Lock then
 816          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 817          pragma Assert (Result = 0 or else Result = ENOMEM);
 818
 819          if Result = 0 then
 820             if Locking_Policy = 'C' then
 821                Result := pthread_mutexattr_setprotocol
 822                  (Mutex_Attr'Access, PTHREAD_PRIO_PROTECT);
 823                pragma Assert (Result = 0);
 824
 825                Result := pthread_mutexattr_setprioceiling
 826                   (Mutex_Attr'Access,
 827                    Interfaces.C.int (System.Any_Priority'Last));
 828                pragma Assert (Result = 0);
 829
 830             elsif Locking_Policy = 'I' then
 831                Result := pthread_mutexattr_setprotocol
 832                  (Mutex_Attr'Access, PTHREAD_PRIO_INHERIT);
 833                pragma Assert (Result = 0);
 834             end if;
 835
 836             Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 837               Mutex_Attr'Access);
 838             pragma Assert (Result = 0 or else Result = ENOMEM);
 839          end if;
 840
 841          if Result /= 0 then
 842             Succeeded := False;
 843             return;
 844          end if;
 845
 846          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 847          pragma Assert (Result = 0);
 848       end if;
 849
 850       Result := pthread_condattr_init (Cond_Attr'Access);
 851       pragma Assert (Result = 0 or else Result = ENOMEM);
 852
 853       if Result = 0 then
 854          Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 855            Cond_Attr'Access);
 856          pragma Assert (Result = 0 or else Result = ENOMEM);
 857       end if;
 858
 859       if Result = 0 then
 860          Succeeded := True;
 861       else
 862          if not Single_Lock then
 863             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 864             pragma Assert (Result = 0);
 865          end if;
 866
 867          Succeeded := False;
 868       end if;
 869
 870       Result := pthread_condattr_destroy (Cond_Attr'Access);
 871       pragma Assert (Result = 0);
 872    end Initialize_TCB;
 873
 874    -----------------
 875    -- Create_Task --
 876    -----------------
 877
 878    procedure Create_Task
 879      (T          : Task_Id;
 880       Wrapper    : System.Address;
 881       Stack_Size : System.Parameters.Size_Type;
 882       Priority   : System.Any_Priority;
 883       Succeeded  : out Boolean)
 884    is
 885       Attributes          : aliased pthread_attr_t;
 886       Adjusted_Stack_Size : Interfaces.C.size_t;
 887       Result              : Interfaces.C.int;
 888
 889       function Thread_Body_Access is new
 890         Unchecked_Conversion (System.Address, Thread_Body);
 891
 892       use System.Task_Info;
 893
 894    begin
 895       if Stack_Size = Unspecified_Size then
 896          Adjusted_Stack_Size := Interfaces.C.size_t (Default_Stack_Size);
 897
 898       elsif Stack_Size < Minimum_Stack_Size then
 899          Adjusted_Stack_Size := Interfaces.C.size_t (Minimum_Stack_Size);
 900
 901       else
 902          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 903       end if;
 904
 905       if Stack_Base_Available then
 906          --  If Stack Checking is supported then allocate 2 additional pages:
 907          --
 908          --  In the worst case, stack is allocated at something like
 909          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 910          --  to be sure the effective stack size is greater than what
 911          --  has been asked.
 912
 913          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Get_Page_Size;
 914       end if;
 915
 916       Result := pthread_attr_init (Attributes'Access);
 917       pragma Assert (Result = 0 or else Result = ENOMEM);
 918
 919       if Result /= 0 then
 920          Succeeded := False;
 921          return;
 922       end if;
 923
 924       Result := pthread_attr_setdetachstate
 925         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 926       pragma Assert (Result = 0);
 927
 928       Result := pthread_attr_setstacksize
 929         (Attributes'Access, Adjusted_Stack_Size);
 930       pragma Assert (Result = 0);
 931
 932       if T.Common.Task_Info /= Default_Scope then
 933
 934          --  We are assuming that Scope_Type has the same values than the
 935          --  corresponding C macros
 936
 937          Result := pthread_attr_setscope
 938            (Attributes'Access, Task_Info_Type'Pos (T.Common.Task_Info));
 939          pragma Assert (Result = 0);
 940       end if;
 941
 942       --  Since the initial signal mask of a thread is inherited from the
 943       --  creator, and the Environment task has all its signals masked, we
 944       --  do not need to manipulate caller's signal mask at this point.
 945       --  All tasks in RTS will have All_Tasks_Mask initially.
 946
 947       Result := pthread_create
 948         (T.Common.LL.Thread'Access,
 949          Attributes'Access,
 950          Thread_Body_Access (Wrapper),
 951          To_Address (T));
 952       pragma Assert (Result = 0 or else Result = EAGAIN);
 953
 954       Succeeded := Result = 0;
 955
 956       Result := pthread_attr_destroy (Attributes'Access);
 957       pragma Assert (Result = 0);
 958
 959       Set_Priority (T, Priority);
 960    end Create_Task;
 961
 962    ------------------
 963    -- Finalize_TCB --
 964    ------------------
 965
 966    procedure Finalize_TCB (T : Task_Id) is
 967       Result  : Interfaces.C.int;
 968       Tmp     : Task_Id := T;
 969       Is_Self : constant Boolean := T = Self;
 970
 971       procedure Free is new
 972         Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 973
 974    begin
 975       if not Single_Lock then
 976          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 977          pragma Assert (Result = 0);
 978       end if;
 979
 980       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 981       pragma Assert (Result = 0);
 982
 983       if T.Known_Tasks_Index /= -1 then
 984          Known_Tasks (T.Known_Tasks_Index) := null;
 985       end if;
 986
 987       Free (Tmp);
 988
 989       if Is_Self then
 990          Specific.Set (null);
 991       end if;
 992    end Finalize_TCB;
 993
 994    ---------------
 995    -- Exit_Task --
 996    ---------------
 997
 998    procedure Exit_Task is
 999    begin
1000       --  Mark this task as unknown, so that if Self is called, it won't
1001       --  return a dangling pointer.
1002
1003       Specific.Set (null);
1004    end Exit_Task;
1005
1006    ----------------
1007    -- Abort_Task --
1008    ----------------
1009
1010    procedure Abort_Task (T : Task_Id) is
1011       Result : Interfaces.C.int;
1012    begin
1013       Result := pthread_kill (T.Common.LL.Thread,
1014         Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1015       pragma Assert (Result = 0);
1016    end Abort_Task;
1017
1018    ----------------
1019    -- Initialize --
1020    ----------------
1021
1022    procedure Initialize (S : in out Suspension_Object) is
1023       Mutex_Attr : aliased pthread_mutexattr_t;
1024       Cond_Attr  : aliased pthread_condattr_t;
1025       Result     : Interfaces.C.int;
1026    begin
1027       --  Initialize internal state. It is always initialized to False (ARM
1028       --  D.10 par. 6).
1029
1030       S.State := False;
1031       S.Waiting := False;
1032
1033       --  Initialize internal mutex
1034
1035       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1036       pragma Assert (Result = 0 or else Result = ENOMEM);
1037
1038       if Result = ENOMEM then
1039          raise Storage_Error;
1040       end if;
1041
1042       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1043       pragma Assert (Result = 0 or else Result = ENOMEM);
1044
1045       if Result = ENOMEM then
1046          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1047          pragma Assert (Result = 0);
1048
1049          raise Storage_Error;
1050       end if;
1051
1052       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1053       pragma Assert (Result = 0);
1054
1055       --  Initialize internal condition variable
1056
1057       Result := pthread_condattr_init (Cond_Attr'Access);
1058       pragma Assert (Result = 0 or else Result = ENOMEM);
1059
1060       if Result /= 0 then
1061          Result := pthread_mutex_destroy (S.L'Access);
1062          pragma Assert (Result = 0);
1063
1064          if Result = ENOMEM then
1065             raise Storage_Error;
1066          end if;
1067       end if;
1068
1069       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1070       pragma Assert (Result = 0 or else Result = ENOMEM);
1071
1072       if Result /= 0 then
1073          Result := pthread_mutex_destroy (S.L'Access);
1074          pragma Assert (Result = 0);
1075
1076          if Result = ENOMEM then
1077             Result := pthread_condattr_destroy (Cond_Attr'Access);
1078             pragma Assert (Result = 0);
1079
1080             raise Storage_Error;
1081          end if;
1082       end if;
1083
1084       Result := pthread_condattr_destroy (Cond_Attr'Access);
1085       pragma Assert (Result = 0);
1086    end Initialize;
1087
1088    --------------
1089    -- Finalize --
1090    --------------
1091
1092    procedure Finalize (S : in out Suspension_Object) is
1093       Result  : Interfaces.C.int;
1094    begin
1095       --  Destroy internal mutex
1096
1097       Result := pthread_mutex_destroy (S.L'Access);
1098       pragma Assert (Result = 0);
1099
1100       --  Destroy internal condition variable
1101
1102       Result := pthread_cond_destroy (S.CV'Access);
1103       pragma Assert (Result = 0);
1104    end Finalize;
1105
1106    -------------------
1107    -- Current_State --
1108    -------------------
1109
1110    function Current_State (S : Suspension_Object) return Boolean is
1111    begin
1112       --  We do not want to use lock on this read operation. State is marked
1113       --  as Atomic so that we ensure that the value retrieved is correct.
1114
1115       return S.State;
1116    end Current_State;
1117
1118    ---------------
1119    -- Set_False --
1120    ---------------
1121
1122    procedure Set_False (S : in out Suspension_Object) is
1123       Result  : Interfaces.C.int;
1124    begin
1125       Result := pthread_mutex_lock (S.L'Access);
1126       pragma Assert (Result = 0);
1127
1128       S.State := False;
1129
1130       Result := pthread_mutex_unlock (S.L'Access);
1131       pragma Assert (Result = 0);
1132    end Set_False;
1133
1134    --------------
1135    -- Set_True --
1136    --------------
1137
1138    procedure Set_True (S : in out Suspension_Object) is
1139       Result : Interfaces.C.int;
1140    begin
1141       Result := pthread_mutex_lock (S.L'Access);
1142       pragma Assert (Result = 0);
1143
1144       --  If there is already a task waiting on this suspension object then
1145       --  we resume it, leaving the state of the suspension object to False,
1146       --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
1147       --  the state to True.
1148
1149       if S.Waiting then
1150          S.Waiting := False;
1151          S.State := False;
1152
1153          Result := pthread_cond_signal (S.CV'Access);
1154          pragma Assert (Result = 0);
1155       else
1156          S.State := True;
1157       end if;
1158
1159       Result := pthread_mutex_unlock (S.L'Access);
1160       pragma Assert (Result = 0);
1161    end Set_True;
1162
1163    ------------------------
1164    -- Suspend_Until_True --
1165    ------------------------
1166
1167    procedure Suspend_Until_True (S : in out Suspension_Object) is
1168       Result : Interfaces.C.int;
1169    begin
1170       Result := pthread_mutex_lock (S.L'Access);
1171       pragma Assert (Result = 0);
1172
1173       if S.Waiting then
1174          --  Program_Error must be raised upon calling Suspend_Until_True
1175          --  if another task is already waiting on that suspension object
1176          --  (ARM D.10 par. 10).
1177
1178          Result := pthread_mutex_unlock (S.L'Access);
1179          pragma Assert (Result = 0);
1180
1181          raise Program_Error;
1182       else
1183          --  Suspend the task if the state is False. Otherwise, the task
1184          --  continues its execution, and the state of the suspension object
1185          --  is set to False (ARM D.10 par. 9).
1186
1187          if S.State then
1188             S.State := False;
1189          else
1190             S.Waiting := True;
1191             Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1192          end if;
1193       end if;
1194
1195       Result := pthread_mutex_unlock (S.L'Access);
1196       pragma Assert (Result = 0);
1197    end Suspend_Until_True;
1198
1199    ----------------
1200    -- Check_Exit --
1201    ----------------
1202
1203    --  Dummy version
1204
1205    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1206       pragma Warnings (Off, Self_ID);
1207    begin
1208       return True;
1209    end Check_Exit;
1210
1211    --------------------
1212    -- Check_No_Locks --
1213    --------------------
1214
1215    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1216       pragma Warnings (Off, Self_ID);
1217    begin
1218       return True;
1219    end Check_No_Locks;
1220
1221    ----------------------
1222    -- Environment_Task --
1223    ----------------------
1224
1225    function Environment_Task return Task_Id is
1226    begin
1227       return Environment_Task_Id;
1228    end Environment_Task;
1229
1230    --------------
1231    -- Lock_RTS --
1232    --------------
1233
1234    procedure Lock_RTS is
1235    begin
1236       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1237    end Lock_RTS;
1238
1239    ----------------
1240    -- Unlock_RTS --
1241    ----------------
1242
1243    procedure Unlock_RTS is
1244    begin
1245       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1246    end Unlock_RTS;
1247
1248    ------------------
1249    -- Suspend_Task --
1250    ------------------
1251
1252    function Suspend_Task
1253      (T           : ST.Task_Id;
1254       Thread_Self : Thread_Id) return Boolean
1255    is
1256       pragma Warnings (Off, T);
1257       pragma Warnings (Off, Thread_Self);
1258    begin
1259       return False;
1260    end Suspend_Task;
1261
1262    -----------------
1263    -- Resume_Task --
1264    -----------------
1265
1266    function Resume_Task
1267      (T           : ST.Task_Id;
1268       Thread_Self : Thread_Id) return Boolean
1269    is
1270       pragma Warnings (Off, T);
1271       pragma Warnings (Off, Thread_Self);
1272    begin
1273       return False;
1274    end Resume_Task;
1275
1276    ----------------
1277    -- Initialize --
1278    ----------------
1279
1280    procedure Initialize (Environment_Task : Task_Id) is
1281       act     : aliased struct_sigaction;
1282       old_act : aliased struct_sigaction;
1283       Tmp_Set : aliased sigset_t;
1284       Result  : Interfaces.C.int;
1285
1286       function State
1287         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1288       pragma Import (C, State, "__gnat_get_interrupt_state");
1289       --  Get interrupt state.  Defined in a-init.c
1290       --  The input argument is the interrupt number,
1291       --  and the result is one of the following:
1292
1293       Default : constant Character := 's';
1294       --    'n'   this interrupt not set by any Interrupt_State pragma
1295       --    'u'   Interrupt_State pragma set state to User
1296       --    'r'   Interrupt_State pragma set state to Runtime
1297       --    's'   Interrupt_State pragma set state to System (use "default"
1298       --           system handler)
1299
1300    begin
1301       Environment_Task_Id := Environment_Task;
1302
1303       Interrupt_Management.Initialize;
1304
1305       --  Prepare the set of signals that should unblocked in all tasks
1306
1307       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1308       pragma Assert (Result = 0);
1309
1310       for J in Interrupt_Management.Interrupt_ID loop
1311          if System.Interrupt_Management.Keep_Unmasked (J) then
1312             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1313             pragma Assert (Result = 0);
1314          end if;
1315       end loop;
1316
1317       --  Initialize the lock used to synchronize chain of all ATCBs.
1318
1319       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1320
1321       Specific.Initialize (Environment_Task);
1322
1323       Enter_Task (Environment_Task);
1324
1325       --  Install the abort-signal handler
1326
1327       if State (System.Interrupt_Management.Abort_Task_Interrupt)
1328         /= Default
1329       then
1330          act.sa_flags := 0;
1331          act.sa_handler := Abort_Handler'Address;
1332
1333          Result := sigemptyset (Tmp_Set'Access);
1334          pragma Assert (Result = 0);
1335          act.sa_mask := Tmp_Set;
1336
1337          Result :=
1338            sigaction
1339            (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1340             act'Unchecked_Access,
1341             old_act'Unchecked_Access);
1342          pragma Assert (Result = 0);
1343       end if;
1344    end Initialize;
1345
1346 end System.Task_Primitives.Operations;