gcc/ada/7staprop.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA 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 --                             $Revision: 1.1 $
  10 --                                                                          --
  11 --             Copyright (C) 1991-2001, Florida State University            --
  12 --                                                                          --
  13 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNARL was developed by the GNARL team at Florida State University. It is --
  32 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  33 -- State University (http://www.gnat.com).                                  --
  34 --                                                                          --
  35 ------------------------------------------------------------------------------
  36
  37 --  This is a POSIX-like version of this package
  38
  39 --  This package contains all the GNULL primitives that interface directly
  40 --  with the underlying OS.
  41
  42 --  Note: this file can only be used for POSIX compliant systems that
  43 --  implement SCHED_FIFO and Ceiling Locking correctly.
  44
  45 --  For configurations where SCHED_FIFO and priority ceiling are not a
  46 --  requirement, this file can also be used (e.g AiX threads)
  47
  48 pragma Polling (Off);
  49 --  Turn off polling, we do not want ATC polling to take place during
  50 --  tasking operations. It causes infinite loops and other problems.
  51
  52 with System.Tasking.Debug;
  53 --  used for Known_Tasks
  54
  55 with System.Task_Info;
  56 --  used for Task_Info_Type
  57
  58 with Interfaces.C;
  59 --  used for int
  60 --           size_t
  61
  62 with System.Interrupt_Management;
  63 --  used for Keep_Unmasked
  64 --           Abort_Task_Interrupt
  65 --           Interrupt_ID
  66
  67 with System.Interrupt_Management.Operations;
  68 --  used for Set_Interrupt_Mask
  69 --           All_Tasks_Mask
  70 pragma Elaborate_All (System.Interrupt_Management.Operations);
  71
  72 with System.Parameters;
  73 --  used for Size_Type
  74
  75 with System.Tasking;
  76 --  used for Ada_Task_Control_Block
  77 --           Task_ID
  78
  79 with System.Soft_Links;
  80 --  used for Defer/Undefer_Abort
  81
  82 --  Note that we do not use System.Tasking.Initialization directly since
  83 --  this is a higher level package that we shouldn't depend on. For example
  84 --  when using the restricted run time, it is replaced by
  85 --  System.Tasking.Restricted.Initialization
  86
  87 with System.OS_Primitives;
  88 --  used for Delay_Modes
  89
  90 with Unchecked_Conversion;
  91 with Unchecked_Deallocation;
  92
  93 package body System.Task_Primitives.Operations is
  94
  95    use System.Tasking.Debug;
  96    use System.Tasking;
  97    use Interfaces.C;
  98    use System.OS_Interface;
  99    use System.Parameters;
 100    use System.OS_Primitives;
 101
 102    package SSL renames System.Soft_Links;
 103
 104    ------------------
 105    --  Local Data  --
 106    ------------------
 107
 108    --  The followings are logically constants, but need to be initialized
 109    --  at run time.
 110
 111    All_Tasks_L : aliased System.Task_Primitives.RTS_Lock;
 112    --  See comments on locking rules in System.Tasking (spec).
 113
 114    Environment_Task_ID : Task_ID;
 115    --  A variable to hold Task_ID for the environment task.
 116
 117    Locking_Policy : Character;
 118    pragma Import (C, Locking_Policy, "__gl_locking_policy");
 119    --  Value of the pragma Locking_Policy:
 120    --    'C' for Ceiling_Locking
 121    --    'I' for Inherit_Locking
 122    --    ' ' for none.
 123
 124    Unblocked_Signal_Mask : aliased sigset_t;
 125    --  The set of signals that should unblocked in all tasks
 126
 127    --  The followings are internal configuration constants needed.
 128
 129    Next_Serial_Number : Task_Serial_Number := 100;
 130    --  We start at 100, to reserve some special values for
 131    --  using in error checking.
 132
 133    Time_Slice_Val : Integer;
 134    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 135
 136    Dispatching_Policy : Character;
 137    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 138
 139    FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
 140    --  Indicates whether FIFO_Within_Priorities is set.
 141
 142    -----------------------
 143    -- Local Subprograms --
 144    -----------------------
 145
 146    procedure Abort_Handler
 147      (Sig     : Signal);
 148
 149    function To_Task_ID is new Unchecked_Conversion (System.Address, Task_ID);
 150
 151    function To_Address is new Unchecked_Conversion (Task_ID, System.Address);
 152
 153    --------------------
 154    -- Local Packages --
 155    --------------------
 156
 157    package Specific is
 158
 159       procedure Initialize (Environment_Task : Task_ID);
 160       pragma Inline (Initialize);
 161       --  Initialize various data needed by this package.
 162
 163       procedure Set (Self_Id : Task_ID);
 164       pragma Inline (Set);
 165       --  Set the self id for the current task.
 166
 167       function Self return Task_ID;
 168       pragma Inline (Self);
 169       --  Return a pointer to the Ada Task Control Block of the calling task.
 170
 171    end Specific;
 172
 173    package body Specific is separate;
 174    --  The body of this package is target specific.
 175
 176    -------------------
 177    -- Abort_Handler --
 178    -------------------
 179
 180    --  Target-dependent binding of inter-thread Abort signal to
 181    --  the raising of the Abort_Signal exception.
 182
 183    --  The technical issues and alternatives here are essentially
 184    --  the same as for raising exceptions in response to other
 185    --  signals (e.g. Storage_Error). See code and comments in
 186    --  the package body System.Interrupt_Management.
 187
 188    --  Some implementations may not allow an exception to be propagated
 189    --  out of a handler, and others might leave the signal or
 190    --  interrupt that invoked this handler masked after the exceptional
 191    --  return to the application code.
 192
 193    --  GNAT exceptions are originally implemented using setjmp()/longjmp().
 194    --  On most UNIX systems, this will allow transfer out of a signal handler,
 195    --  which is usually the only mechanism available for implementing
 196    --  asynchronous handlers of this kind. However, some
 197    --  systems do not restore the signal mask on longjmp(), leaving the
 198    --  abort signal masked.
 199
 200    --  Alternative solutions include:
 201
 202    --       1. Change the PC saved in the system-dependent Context
 203    --          parameter to point to code that raises the exception.
 204    --          Normal return from this handler will then raise
 205    --          the exception after the mask and other system state has
 206    --          been restored (see example below).
 207
 208    --       2. Use siglongjmp()/sigsetjmp() to implement exceptions.
 209
 210    --       3. Unmask the signal in the Abortion_Signal exception handler
 211    --          (in the RTS).
 212
 213    --  The following procedure would be needed if we can't lonjmp out of
 214    --  a signal handler  (See below)
 215
 216    --  procedure Raise_Abort_Signal is
 217    --  begin
 218    --     raise Standard'Abort_Signal;
 219    --  end if;
 220
 221    procedure Abort_Handler
 222      (Sig     : Signal) is
 223
 224       T       : Task_ID := Self;
 225       Result  : Interfaces.C.int;
 226       Old_Set : aliased sigset_t;
 227
 228    begin
 229       --  Assuming it is safe to longjmp out of a signal handler, the
 230       --  following code can be used:
 231
 232       if T.Deferral_Level = 0
 233         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 234         not T.Aborting
 235       then
 236          T.Aborting := True;
 237
 238          --  Make sure signals used for RTS internal purpose are unmasked
 239
 240          Result := pthread_sigmask (SIG_UNBLOCK,
 241            Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access);
 242          pragma Assert (Result = 0);
 243
 244          raise Standard'Abort_Signal;
 245       end if;
 246
 247       --  Otherwise, something like this is required:
 248       --  if not Abort_Is_Deferred.all then
 249       --    --  Overwrite the return PC address with the address of the
 250       --    --  special raise routine, and "return" to that routine's
 251       --    --  starting address.
 252       --    Context.PC := Raise_Abort_Signal'Address;
 253       --    return;
 254       --  end if;
 255
 256    end Abort_Handler;
 257
 258    -------------------
 259    --  Stack_Guard  --
 260    -------------------
 261
 262    procedure Stack_Guard (T : ST.Task_ID; On : Boolean) is
 263
 264       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 265       Guard_Page_Address : Address;
 266
 267       Res : Interfaces.C.int;
 268
 269    begin
 270       if Stack_Base_Available then
 271          --  Compute the guard page address
 272
 273          Guard_Page_Address :=
 274            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 275
 276          if On then
 277             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_ON);
 278          else
 279             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_OFF);
 280          end if;
 281
 282          pragma Assert (Res = 0);
 283       end if;
 284    end Stack_Guard;
 285
 286    --------------------
 287    -- Get_Thread_Id  --
 288    --------------------
 289
 290    function Get_Thread_Id (T : ST.Task_ID) return OSI.Thread_Id is
 291    begin
 292       return T.Common.LL.Thread;
 293    end Get_Thread_Id;
 294
 295    ----------
 296    -- Self --
 297    ----------
 298
 299    function Self return Task_ID renames Specific.Self;
 300
 301    ---------------------
 302    -- Initialize_Lock --
 303    ---------------------
 304
 305    --  Note: mutexes and cond_variables needed per-task basis are
 306    --        initialized in Initialize_TCB and the Storage_Error is
 307    --        handled. Other mutexes (such as All_Tasks_Lock, Memory_Lock...)
 308    --        used in RTS is initialized before any status change of RTS.
 309    --        Therefore rasing Storage_Error in the following routines
 310    --        should be able to be handled safely.
 311
 312    procedure Initialize_Lock
 313      (Prio : System.Any_Priority;
 314       L    : access Lock)
 315    is
 316       Attributes : aliased pthread_mutexattr_t;
 317       Result : Interfaces.C.int;
 318
 319    begin
 320       Result := pthread_mutexattr_init (Attributes'Access);
 321       pragma Assert (Result = 0 or else Result = ENOMEM);
 322
 323       if Result = ENOMEM then
 324          raise Storage_Error;
 325       end if;
 326
 327       if Locking_Policy = 'C' then
 328          Result := pthread_mutexattr_setprotocol
 329            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 330          pragma Assert (Result = 0);
 331
 332          Result := pthread_mutexattr_setprioceiling
 333             (Attributes'Access, Interfaces.C.int (Prio));
 334          pragma Assert (Result = 0);
 335
 336       elsif Locking_Policy = 'I' then
 337          Result := pthread_mutexattr_setprotocol
 338            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 339          pragma Assert (Result = 0);
 340       end if;
 341
 342       Result := pthread_mutex_init (L, Attributes'Access);
 343       pragma Assert (Result = 0 or else Result = ENOMEM);
 344
 345       if Result = ENOMEM then
 346          raise Storage_Error;
 347       end if;
 348
 349       Result := pthread_mutexattr_destroy (Attributes'Access);
 350       pragma Assert (Result = 0);
 351    end Initialize_Lock;
 352
 353    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 354       Attributes : aliased pthread_mutexattr_t;
 355       Result : Interfaces.C.int;
 356
 357    begin
 358       Result := pthread_mutexattr_init (Attributes'Access);
 359       pragma Assert (Result = 0 or else Result = ENOMEM);
 360
 361       if Result = ENOMEM then
 362          raise Storage_Error;
 363       end if;
 364
 365       if Locking_Policy = 'C' then
 366          Result := pthread_mutexattr_setprotocol
 367            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 368          pragma Assert (Result = 0);
 369
 370          Result := pthread_mutexattr_setprioceiling
 371             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 372          pragma Assert (Result = 0);
 373
 374       elsif Locking_Policy = 'I' then
 375          Result := pthread_mutexattr_setprotocol
 376            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 377          pragma Assert (Result = 0);
 378       end if;
 379
 380       Result := pthread_mutex_init (L, Attributes'Access);
 381       pragma Assert (Result = 0 or else Result = ENOMEM);
 382
 383       if Result = ENOMEM then
 384          Result := pthread_mutexattr_destroy (Attributes'Access);
 385          raise Storage_Error;
 386       end if;
 387
 388       Result := pthread_mutexattr_destroy (Attributes'Access);
 389       pragma Assert (Result = 0);
 390    end Initialize_Lock;
 391
 392    -------------------
 393    -- Finalize_Lock --
 394    -------------------
 395
 396    procedure Finalize_Lock (L : access Lock) is
 397       Result : Interfaces.C.int;
 398
 399    begin
 400       Result := pthread_mutex_destroy (L);
 401       pragma Assert (Result = 0);
 402    end Finalize_Lock;
 403
 404    procedure Finalize_Lock (L : access RTS_Lock) is
 405       Result : Interfaces.C.int;
 406
 407    begin
 408       Result := pthread_mutex_destroy (L);
 409       pragma Assert (Result = 0);
 410    end Finalize_Lock;
 411
 412    ----------------
 413    -- Write_Lock --
 414    ----------------
 415
 416    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 417       Result : Interfaces.C.int;
 418
 419    begin
 420       Result := pthread_mutex_lock (L);
 421
 422       --  Assume that the cause of EINVAL is a priority ceiling violation
 423
 424       Ceiling_Violation := (Result = EINVAL);
 425       pragma Assert (Result = 0 or else Result = EINVAL);
 426    end Write_Lock;
 427
 428    procedure Write_Lock (L : access RTS_Lock) is
 429       Result : Interfaces.C.int;
 430
 431    begin
 432       Result := pthread_mutex_lock (L);
 433       pragma Assert (Result = 0);
 434    end Write_Lock;
 435
 436    procedure Write_Lock (T : Task_ID) is
 437       Result : Interfaces.C.int;
 438
 439    begin
 440       Result := pthread_mutex_lock (T.Common.LL.L'Access);
 441       pragma Assert (Result = 0);
 442    end Write_Lock;
 443
 444    ---------------
 445    -- Read_Lock --
 446    ---------------
 447
 448    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 449    begin
 450       Write_Lock (L, Ceiling_Violation);
 451    end Read_Lock;
 452
 453    ------------
 454    -- Unlock --
 455    ------------
 456
 457    procedure Unlock (L : access Lock) is
 458       Result : Interfaces.C.int;
 459
 460    begin
 461       Result := pthread_mutex_unlock (L);
 462       pragma Assert (Result = 0);
 463    end Unlock;
 464
 465    procedure Unlock (L : access RTS_Lock) is
 466       Result : Interfaces.C.int;
 467
 468    begin
 469       Result := pthread_mutex_unlock (L);
 470       pragma Assert (Result = 0);
 471    end Unlock;
 472
 473    procedure Unlock (T : Task_ID) is
 474       Result : Interfaces.C.int;
 475
 476    begin
 477       Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 478       pragma Assert (Result = 0);
 479    end Unlock;
 480
 481    -------------
 482    --  Sleep  --
 483    -------------
 484
 485    procedure Sleep (Self_ID : Task_ID;
 486                     Reason   : System.Tasking.Task_States) is
 487       Result : Interfaces.C.int;
 488
 489    begin
 490       pragma Assert (Self_ID = Self);
 491       Result := pthread_cond_wait (Self_ID.Common.LL.CV'Access,
 492         Self_ID.Common.LL.L'Access);
 493
 494       --  EINTR is not considered a failure.
 495
 496       pragma Assert (Result = 0 or else Result = EINTR);
 497    end Sleep;
 498
 499    -----------------
 500    -- Timed_Sleep --
 501    -----------------
 502
 503    --  This is for use within the run-time system, so abort is
 504    --  assumed to be already deferred, and the caller should be
 505    --  holding its own ATCB lock.
 506
 507    procedure Timed_Sleep
 508      (Self_ID  : Task_ID;
 509       Time     : Duration;
 510       Mode     : ST.Delay_Modes;
 511       Reason   : Task_States;
 512       Timedout : out Boolean;
 513       Yielded  : out Boolean)
 514    is
 515       Check_Time : constant Duration := Monotonic_Clock;
 516       Rel_Time   : Duration;
 517       Abs_Time   : Duration;
 518       Request    : aliased timespec;
 519       Result     : Interfaces.C.int;
 520
 521    begin
 522       Timedout := True;
 523       Yielded := False;
 524
 525       if Mode = Relative then
 526          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 527
 528          if Relative_Timed_Wait then
 529             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 530          end if;
 531
 532       else
 533          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 534
 535          if Relative_Timed_Wait then
 536             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 537          end if;
 538       end if;
 539
 540       if Abs_Time > Check_Time then
 541          if Relative_Timed_Wait then
 542             Request := To_Timespec (Rel_Time);
 543          else
 544             Request := To_Timespec (Abs_Time);
 545          end if;
 546
 547          loop
 548             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 549               or else Self_ID.Pending_Priority_Change;
 550
 551             Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 552               Self_ID.Common.LL.L'Access, Request'Access);
 553
 554             exit when Abs_Time <= Monotonic_Clock;
 555
 556             if Result = 0 or Result = EINTR then
 557
 558                --  Somebody may have called Wakeup for us
 559
 560                Timedout := False;
 561                exit;
 562             end if;
 563
 564             pragma Assert (Result = ETIMEDOUT);
 565          end loop;
 566       end if;
 567    end Timed_Sleep;
 568
 569    -----------------
 570    -- Timed_Delay --
 571    -----------------
 572
 573    --  This is for use in implementing delay statements, so
 574    --  we assume the caller is abort-deferred but is holding
 575    --  no locks.
 576
 577    procedure Timed_Delay
 578      (Self_ID  : Task_ID;
 579       Time     : Duration;
 580       Mode     : ST.Delay_Modes)
 581    is
 582       Check_Time : constant Duration := Monotonic_Clock;
 583       Abs_Time   : Duration;
 584       Rel_Time   : Duration;
 585       Request    : aliased timespec;
 586       Result     : Interfaces.C.int;
 587
 588    begin
 589       --  Only the little window between deferring abort and
 590       --  locking Self_ID is the reason we need to
 591       --  check for pending abort and priority change below! :(
 592
 593       SSL.Abort_Defer.all;
 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             Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 630               Self_ID.Common.LL.L'Access, Request'Access);
 631             exit when Abs_Time <= Monotonic_Clock;
 632
 633             pragma Assert (Result = 0
 634                              or else Result = ETIMEDOUT
 635                              or else Result = EINTR);
 636          end loop;
 637
 638          Self_ID.Common.State := Runnable;
 639       end if;
 640
 641       Unlock (Self_ID);
 642       Result := sched_yield;
 643       SSL.Abort_Undefer.all;
 644    end Timed_Delay;
 645
 646    ---------------------
 647    -- Monotonic_Clock --
 648    ---------------------
 649
 650    function Monotonic_Clock return Duration is
 651       TS     : aliased timespec;
 652       Result : Interfaces.C.int;
 653
 654    begin
 655       Result := clock_gettime
 656         (clock_id => CLOCK_REALTIME, tp => TS'Unchecked_Access);
 657       pragma Assert (Result = 0);
 658       return To_Duration (TS);
 659    end Monotonic_Clock;
 660
 661    -------------------
 662    -- RT_Resolution --
 663    -------------------
 664
 665    function RT_Resolution return Duration is
 666    begin
 667       return 10#1.0#E-6;
 668    end RT_Resolution;
 669
 670    ------------
 671    -- Wakeup --
 672    ------------
 673
 674    procedure Wakeup (T : Task_ID; Reason : System.Tasking.Task_States) is
 675       Result : Interfaces.C.int;
 676
 677    begin
 678       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 679       pragma Assert (Result = 0);
 680    end Wakeup;
 681
 682    -----------
 683    -- Yield --
 684    -----------
 685
 686    procedure Yield (Do_Yield : Boolean := True) is
 687       Result : Interfaces.C.int;
 688
 689    begin
 690       if Do_Yield then
 691          Result := sched_yield;
 692       end if;
 693    end Yield;
 694
 695    ------------------
 696    -- Set_Priority --
 697    ------------------
 698
 699    procedure Set_Priority
 700      (T : Task_ID;
 701       Prio : System.Any_Priority;
 702       Loss_Of_Inheritance : Boolean := False)
 703    is
 704       Result : Interfaces.C.int;
 705       Param  : aliased struct_sched_param;
 706
 707    begin
 708       T.Common.Current_Priority := Prio;
 709       Param.sched_priority := Interfaces.C.int (Prio);
 710
 711       if Time_Slice_Supported and then Time_Slice_Val > 0 then
 712          Result := pthread_setschedparam
 713            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 714
 715       elsif FIFO_Within_Priorities or else Time_Slice_Val = 0 then
 716          Result := pthread_setschedparam
 717            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 718
 719       else
 720          Result := pthread_setschedparam
 721            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 722       end if;
 723
 724       pragma Assert (Result = 0);
 725    end Set_Priority;
 726
 727    ------------------
 728    -- Get_Priority --
 729    ------------------
 730
 731    function Get_Priority (T : Task_ID) return System.Any_Priority is
 732    begin
 733       return T.Common.Current_Priority;
 734    end Get_Priority;
 735
 736    ----------------
 737    -- Enter_Task --
 738    ----------------
 739
 740    procedure Enter_Task (Self_ID : Task_ID) is
 741    begin
 742       Self_ID.Common.LL.Thread := pthread_self;
 743       Self_ID.Common.LL.LWP := lwp_self;
 744
 745       Specific.Set (Self_ID);
 746
 747       Lock_All_Tasks_List;
 748
 749       for I in Known_Tasks'Range loop
 750          if Known_Tasks (I) = null then
 751             Known_Tasks (I) := Self_ID;
 752             Self_ID.Known_Tasks_Index := I;
 753             exit;
 754          end if;
 755       end loop;
 756
 757       Unlock_All_Tasks_List;
 758    end Enter_Task;
 759
 760    --------------
 761    -- New_ATCB --
 762    --------------
 763
 764    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_ID is
 765    begin
 766       return new Ada_Task_Control_Block (Entry_Num);
 767    end New_ATCB;
 768
 769    ----------------------
 770    --  Initialize_TCB  --
 771    ----------------------
 772
 773    procedure Initialize_TCB (Self_ID : Task_ID; Succeeded : out Boolean) is
 774       Mutex_Attr : aliased pthread_mutexattr_t;
 775       Result : Interfaces.C.int;
 776       Cond_Attr : aliased pthread_condattr_t;
 777
 778    begin
 779       --  Give the task a unique serial number.
 780
 781       Self_ID.Serial_Number := Next_Serial_Number;
 782       Next_Serial_Number := Next_Serial_Number + 1;
 783       pragma Assert (Next_Serial_Number /= 0);
 784
 785       Result := pthread_mutexattr_init (Mutex_Attr'Access);
 786       pragma Assert (Result = 0 or else Result = ENOMEM);
 787
 788       if Result /= 0 then
 789          Succeeded := False;
 790          return;
 791       end if;
 792
 793       Result := pthread_mutexattr_setprotocol
 794         (Mutex_Attr'Access, PTHREAD_PRIO_PROTECT);
 795       pragma Assert (Result = 0);
 796
 797       Result := pthread_mutexattr_setprioceiling
 798         (Mutex_Attr'Access, Interfaces.C.int (System.Any_Priority'Last));
 799       pragma Assert (Result = 0);
 800
 801       Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 802         Mutex_Attr'Access);
 803       pragma Assert (Result = 0 or else Result = ENOMEM);
 804
 805       if Result /= 0 then
 806          Succeeded := False;
 807          return;
 808       end if;
 809
 810       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 811       pragma Assert (Result = 0);
 812
 813       Result := pthread_condattr_init (Cond_Attr'Access);
 814       pragma Assert (Result = 0 or else Result = ENOMEM);
 815
 816       if Result /= 0 then
 817          Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 818          pragma Assert (Result = 0);
 819          Succeeded := False;
 820          return;
 821       end if;
 822
 823       Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 824         Cond_Attr'Access);
 825       pragma Assert (Result = 0 or else Result = ENOMEM);
 826
 827       if Result = 0 then
 828          Succeeded := True;
 829       else
 830          Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 831          pragma Assert (Result = 0);
 832          Succeeded := False;
 833       end if;
 834
 835       Result := pthread_condattr_destroy (Cond_Attr'Access);
 836       pragma Assert (Result = 0);
 837    end Initialize_TCB;
 838
 839    -----------------
 840    -- Create_Task --
 841    -----------------
 842
 843    procedure Create_Task
 844      (T          : Task_ID;
 845       Wrapper    : System.Address;
 846       Stack_Size : System.Parameters.Size_Type;
 847       Priority   : System.Any_Priority;
 848       Succeeded  : out Boolean)
 849    is
 850       Attributes          : aliased pthread_attr_t;
 851       Adjusted_Stack_Size : Interfaces.C.size_t;
 852       Result              : Interfaces.C.int;
 853
 854       function Thread_Body_Access is new
 855         Unchecked_Conversion (System.Address, Thread_Body);
 856
 857       use System.Task_Info;
 858
 859    begin
 860       if Stack_Size = Unspecified_Size then
 861          Adjusted_Stack_Size := Interfaces.C.size_t (Default_Stack_Size);
 862
 863       elsif Stack_Size < Minimum_Stack_Size then
 864          Adjusted_Stack_Size := Interfaces.C.size_t (Minimum_Stack_Size);
 865
 866       else
 867          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 868       end if;
 869
 870       if Stack_Base_Available then
 871          --  If Stack Checking is supported then allocate 2 additional pages:
 872          --
 873          --  In the worst case, stack is allocated at something like
 874          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 875          --  to be sure the effective stack size is greater than what
 876          --  has been asked.
 877
 878          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Get_Page_Size;
 879       end if;
 880
 881       Result := pthread_attr_init (Attributes'Access);
 882       pragma Assert (Result = 0 or else Result = ENOMEM);
 883
 884       if Result /= 0 then
 885          Succeeded := False;
 886          return;
 887       end if;
 888
 889       Result := pthread_attr_setdetachstate
 890         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 891       pragma Assert (Result = 0);
 892
 893       Result := pthread_attr_setstacksize
 894         (Attributes'Access, Adjusted_Stack_Size);
 895       pragma Assert (Result = 0);
 896
 897       if T.Common.Task_Info /= Default_Scope then
 898
 899          --  We are assuming that Scope_Type has the same values than the
 900          --  corresponding C macros
 901
 902          Result := pthread_attr_setscope
 903            (Attributes'Access, Task_Info_Type'Pos (T.Common.Task_Info));
 904          pragma Assert (Result = 0);
 905       end if;
 906
 907       --  Since the initial signal mask of a thread is inherited from the
 908       --  creator, and the Environment task has all its signals masked, we
 909       --  do not need to manipulate caller's signal mask at this point.
 910       --  All tasks in RTS will have All_Tasks_Mask initially.
 911
 912       Result := pthread_create
 913         (T.Common.LL.Thread'Access,
 914          Attributes'Access,
 915          Thread_Body_Access (Wrapper),
 916          To_Address (T));
 917       pragma Assert (Result = 0 or else Result = EAGAIN);
 918
 919       Succeeded := Result = 0;
 920
 921       Result := pthread_attr_destroy (Attributes'Access);
 922       pragma Assert (Result = 0);
 923
 924       Set_Priority (T, Priority);
 925    end Create_Task;
 926
 927    ------------------
 928    -- Finalize_TCB --
 929    ------------------
 930
 931    procedure Finalize_TCB (T : Task_ID) is
 932       Result : Interfaces.C.int;
 933       Tmp    : Task_ID := T;
 934
 935       procedure Free is new
 936         Unchecked_Deallocation (Ada_Task_Control_Block, Task_ID);
 937
 938    begin
 939       Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 940       pragma Assert (Result = 0);
 941
 942       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 943       pragma Assert (Result = 0);
 944
 945       if T.Known_Tasks_Index /= -1 then
 946          Known_Tasks (T.Known_Tasks_Index) := null;
 947       end if;
 948
 949       Free (Tmp);
 950    end Finalize_TCB;
 951
 952    ---------------
 953    -- Exit_Task --
 954    ---------------
 955
 956    procedure Exit_Task is
 957    begin
 958       pthread_exit (System.Null_Address);
 959    end Exit_Task;
 960
 961    ----------------
 962    -- Abort_Task --
 963    ----------------
 964
 965    procedure Abort_Task (T : Task_ID) is
 966       Result : Interfaces.C.int;
 967
 968    begin
 969       Result := pthread_kill (T.Common.LL.Thread,
 970         Signal (System.Interrupt_Management.Abort_Task_Interrupt));
 971       pragma Assert (Result = 0);
 972    end Abort_Task;
 973
 974    ----------------
 975    -- Check_Exit --
 976    ----------------
 977
 978    --  Dummy versions. The only currently working versions is for solaris
 979    --  (native).
 980
 981    function Check_Exit (Self_ID : ST.Task_ID) return Boolean is
 982    begin
 983       return True;
 984    end Check_Exit;
 985
 986    --------------------
 987    -- Check_No_Locks --
 988    --------------------
 989
 990    function Check_No_Locks (Self_ID : ST.Task_ID) return Boolean is
 991    begin
 992       return True;
 993    end Check_No_Locks;
 994
 995    ----------------------
 996    -- Environment_Task --
 997    ----------------------
 998
 999    function Environment_Task return Task_ID is
1000    begin
1001       return Environment_Task_ID;
1002    end Environment_Task;
1003
1004    -------------------------
1005    -- Lock_All_Tasks_List --
1006    -------------------------
1007
1008    procedure Lock_All_Tasks_List is
1009    begin
1010       Write_Lock (All_Tasks_L'Access);
1011    end Lock_All_Tasks_List;
1012
1013    ---------------------------
1014    -- Unlock_All_Tasks_List --
1015    ---------------------------
1016
1017    procedure Unlock_All_Tasks_List is
1018    begin
1019       Unlock (All_Tasks_L'Access);
1020    end Unlock_All_Tasks_List;
1021
1022    ------------------
1023    -- Suspend_Task --
1024    ------------------
1025
1026    function Suspend_Task
1027      (T           : ST.Task_ID;
1028       Thread_Self : Thread_Id) return Boolean is
1029    begin
1030       return False;
1031    end Suspend_Task;
1032
1033    -----------------
1034    -- Resume_Task --
1035    -----------------
1036
1037    function Resume_Task
1038      (T           : ST.Task_ID;
1039       Thread_Self : Thread_Id) return Boolean is
1040    begin
1041       return False;
1042    end Resume_Task;
1043
1044    ----------------
1045    -- Initialize --
1046    ----------------
1047
1048    procedure Initialize (Environment_Task : Task_ID) is
1049       act     : aliased struct_sigaction;
1050       old_act : aliased struct_sigaction;
1051       Tmp_Set : aliased sigset_t;
1052       Result  : Interfaces.C.int;
1053
1054    begin
1055       Environment_Task_ID := Environment_Task;
1056
1057       --  Initialize the lock used to synchronize chain of all ATCBs.
1058
1059       Initialize_Lock (All_Tasks_L'Access, All_Tasks_Level);
1060
1061       Specific.Initialize (Environment_Task);
1062
1063       Enter_Task (Environment_Task);
1064
1065       --  Install the abort-signal handler
1066
1067       act.sa_flags := 0;
1068       act.sa_handler := Abort_Handler'Address;
1069
1070       Result := sigemptyset (Tmp_Set'Access);
1071       pragma Assert (Result = 0);
1072       act.sa_mask := Tmp_Set;
1073
1074       Result :=
1075         sigaction (
1076           Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1077           act'Unchecked_Access,
1078           old_act'Unchecked_Access);
1079
1080       pragma Assert (Result = 0);
1081    end Initialize;
1082
1083 begin
1084    declare
1085       Result : Interfaces.C.int;
1086
1087    begin
1088       --  Mask Environment task for all signals. The original mask of the
1089       --  Environment task will be recovered by Interrupt_Server task
1090       --  during the elaboration of s-interr.adb.
1091
1092       System.Interrupt_Management.Operations.Set_Interrupt_Mask
1093         (System.Interrupt_Management.Operations.All_Tasks_Mask'Access);
1094
1095       --  Prepare the set of signals that should unblocked in all tasks
1096
1097       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1098       pragma Assert (Result = 0);
1099
1100       for J in Interrupt_Management.Interrupt_ID loop
1101          if System.Interrupt_Management.Keep_Unmasked (J) then
1102             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1103             pragma Assert (Result = 0);
1104          end if;
1105       end loop;
1106    end;
1107
1108 end System.Task_Primitives.Operations;