gcc/ada/s-taprop-posix.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 --         Copyright (C) 1992-2004, 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,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, 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.Task_Info;
  53 --  used for Task_Info_Type
  54
  55 with Interfaces.C;
  56 --  used for int
  57 --           size_t
  58
  59 with System.Interrupt_Management;
  60 --  used for Keep_Unmasked
  61 --           Abort_Task_Interrupt
  62 --           Interrupt_ID
  63
  64 with System.Interrupt_Management.Operations;
  65 --  used for Set_Interrupt_Mask
  66 --           All_Tasks_Mask
  67 pragma Elaborate_All (System.Interrupt_Management.Operations);
  68
  69 with System.Parameters;
  70 --  used for Size_Type
  71
  72 with System.Tasking;
  73 --  used for Ada_Task_Control_Block
  74 --           Task_ID
  75
  76 with System.Soft_Links;
  77 --  used for Defer/Undefer_Abort
  78
  79 --  Note that we do not use System.Tasking.Initialization directly since
  80 --  this is a higher level package that we shouldn't depend on. For example
  81 --  when using the restricted run time, it is replaced by
  82 --  System.Tasking.Restricted.Initialization
  83
  84 with System.OS_Primitives;
  85 --  used for Delay_Modes
  86
  87 with Unchecked_Conversion;
  88 with Unchecked_Deallocation;
  89
  90 package body System.Task_Primitives.Operations is
  91
  92    use System.Tasking.Debug;
  93    use System.Tasking;
  94    use Interfaces.C;
  95    use System.OS_Interface;
  96    use System.Parameters;
  97    use System.OS_Primitives;
  98
  99    package SSL renames System.Soft_Links;
 100
 101    ----------------
 102    -- Local Data --
 103    ----------------
 104
 105    --  The followings are logically constants, but need to be initialized
 106    --  at run time.
 107
 108    Single_RTS_Lock : aliased RTS_Lock;
 109    --  This is a lock to allow only one thread of control in the RTS at
 110    --  a time; it is used to execute in mutual exclusion from all other tasks.
 111    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 112
 113    ATCB_Key : aliased pthread_key_t;
 114    --  Key used to find the Ada Task_ID associated with a thread
 115
 116    Environment_Task_ID : Task_ID;
 117    --  A variable to hold Task_ID for the environment task.
 118
 119    Locking_Policy : Character;
 120    pragma Import (C, Locking_Policy, "__gl_locking_policy");
 121    --  Value of the pragma Locking_Policy:
 122    --    'C' for Ceiling_Locking
 123    --    'I' for Inherit_Locking
 124    --    ' ' for none.
 125
 126    Unblocked_Signal_Mask : aliased sigset_t;
 127    --  The set of signals that should unblocked in all tasks
 128
 129    --  The followings are internal configuration constants needed.
 130
 131    Next_Serial_Number : Task_Serial_Number := 100;
 132    --  We start at 100, to reserve some special values for
 133    --  using in error checking.
 134
 135    Time_Slice_Val : Integer;
 136    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 137
 138    Dispatching_Policy : Character;
 139    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 140
 141    FIFO_Within_Priorities : constant Boolean := Dispatching_Policy = 'F';
 142    --  Indicates whether FIFO_Within_Priorities is set.
 143
 144    Foreign_Task_Elaborated : aliased Boolean := True;
 145    --  Used to identified fake tasks (i.e., non-Ada Threads).
 146
 147    --------------------
 148    -- Local Packages --
 149    --------------------
 150
 151    package Specific is
 152
 153       procedure Initialize (Environment_Task : Task_ID);
 154       pragma Inline (Initialize);
 155       --  Initialize various data needed by this package.
 156
 157       function Is_Valid_Task return Boolean;
 158       pragma Inline (Is_Valid_Task);
 159       --  Does executing thread have a TCB?
 160
 161       procedure Set (Self_Id : Task_ID);
 162       pragma Inline (Set);
 163       --  Set the self id for the current task.
 164
 165       function Self return Task_ID;
 166       pragma Inline (Self);
 167       --  Return a pointer to the Ada Task Control Block of the calling task.
 168
 169    end Specific;
 170
 171    package body Specific is separate;
 172    --  The body of this package is target specific.
 173
 174    ---------------------------------
 175    -- Support for foreign threads --
 176    ---------------------------------
 177
 178    function Register_Foreign_Thread (Thread : Thread_Id) return Task_ID;
 179    --  Allocate and Initialize a new ATCB for the current Thread.
 180
 181    function Register_Foreign_Thread
 182      (Thread : Thread_Id) return Task_ID is separate;
 183
 184    -----------------------
 185    -- Local Subprograms --
 186    -----------------------
 187
 188    procedure Abort_Handler (Sig : Signal);
 189    --  Signal handler used to implement asynchronous abort.
 190    --  See also comment before body, below.
 191
 192    function To_Address is new Unchecked_Conversion (Task_ID, System.Address);
 193
 194    -------------------
 195    -- Abort_Handler --
 196    -------------------
 197
 198    --  Target-dependent binding of inter-thread Abort signal to
 199    --  the raising of the Abort_Signal exception.
 200
 201    --  The technical issues and alternatives here are essentially
 202    --  the same as for raising exceptions in response to other
 203    --  signals (e.g. Storage_Error). See code and comments in
 204    --  the package body System.Interrupt_Management.
 205
 206    --  Some implementations may not allow an exception to be propagated
 207    --  out of a handler, and others might leave the signal or
 208    --  interrupt that invoked this handler masked after the exceptional
 209    --  return to the application code.
 210
 211    --  GNAT exceptions are originally implemented using setjmp()/longjmp().
 212    --  On most UNIX systems, this will allow transfer out of a signal handler,
 213    --  which is usually the only mechanism available for implementing
 214    --  asynchronous handlers of this kind. However, some
 215    --  systems do not restore the signal mask on longjmp(), leaving the
 216    --  abort signal masked.
 217
 218    procedure Abort_Handler (Sig : Signal) is
 219       pragma Warnings (Off, Sig);
 220
 221       T       : constant Task_ID := Self;
 222       Result  : Interfaces.C.int;
 223       Old_Set : aliased sigset_t;
 224
 225    begin
 226       --  It is not safe to raise an exception when using ZCX and the GCC
 227       --  exception handling mechanism.
 228
 229       if ZCX_By_Default and then GCC_ZCX_Support then
 230          return;
 231       end if;
 232
 233       if T.Deferral_Level = 0
 234         and then T.Pending_ATC_Level < T.ATC_Nesting_Level and then
 235         not T.Aborting
 236       then
 237          T.Aborting := True;
 238
 239          --  Make sure signals used for RTS internal purpose are unmasked
 240
 241          Result := pthread_sigmask (SIG_UNBLOCK,
 242            Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access);
 243          pragma Assert (Result = 0);
 244
 245          raise Standard'Abort_Signal;
 246       end if;
 247    end Abort_Handler;
 248
 249    -----------------
 250    -- Stack_Guard --
 251    -----------------
 252
 253    procedure Stack_Guard (T : ST.Task_ID; On : Boolean) is
 254       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 255       Guard_Page_Address : Address;
 256
 257       Res : Interfaces.C.int;
 258
 259    begin
 260       if Stack_Base_Available then
 261
 262          --  Compute the guard page address
 263
 264          Guard_Page_Address :=
 265            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 266
 267          if On then
 268             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_ON);
 269          else
 270             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_OFF);
 271          end if;
 272
 273          pragma Assert (Res = 0);
 274       end if;
 275    end Stack_Guard;
 276
 277    --------------------
 278    -- Get_Thread_Id  --
 279    --------------------
 280
 281    function Get_Thread_Id (T : ST.Task_ID) return OSI.Thread_Id is
 282    begin
 283       return T.Common.LL.Thread;
 284    end Get_Thread_Id;
 285
 286    ----------
 287    -- Self --
 288    ----------
 289
 290    function Self return Task_ID renames Specific.Self;
 291
 292    ---------------------
 293    -- Initialize_Lock --
 294    ---------------------
 295
 296    --  Note: mutexes and cond_variables needed per-task basis are
 297    --        initialized in Intialize_TCB and the Storage_Error is
 298    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 299    --        used in RTS is initialized before any status change of RTS.
 300    --        Therefore rasing Storage_Error in the following routines
 301    --        should be able to be handled safely.
 302
 303    procedure Initialize_Lock
 304      (Prio : System.Any_Priority;
 305       L    : access Lock)
 306    is
 307       Attributes : aliased pthread_mutexattr_t;
 308       Result : Interfaces.C.int;
 309
 310    begin
 311       Result := pthread_mutexattr_init (Attributes'Access);
 312       pragma Assert (Result = 0 or else Result = ENOMEM);
 313
 314       if Result = ENOMEM then
 315          raise Storage_Error;
 316       end if;
 317
 318       if Locking_Policy = 'C' then
 319          Result := pthread_mutexattr_setprotocol
 320            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 321          pragma Assert (Result = 0);
 322
 323          Result := pthread_mutexattr_setprioceiling
 324             (Attributes'Access, Interfaces.C.int (Prio));
 325          pragma Assert (Result = 0);
 326
 327       elsif Locking_Policy = 'I' then
 328          Result := pthread_mutexattr_setprotocol
 329            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 330          pragma Assert (Result = 0);
 331       end if;
 332
 333       Result := pthread_mutex_init (L, Attributes'Access);
 334       pragma Assert (Result = 0 or else Result = ENOMEM);
 335
 336       if Result = ENOMEM then
 337          raise Storage_Error;
 338       end if;
 339
 340       Result := pthread_mutexattr_destroy (Attributes'Access);
 341       pragma Assert (Result = 0);
 342    end Initialize_Lock;
 343
 344    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 345       pragma Warnings (Off, Level);
 346
 347       Attributes : aliased pthread_mutexattr_t;
 348       Result     : Interfaces.C.int;
 349
 350    begin
 351       Result := pthread_mutexattr_init (Attributes'Access);
 352       pragma Assert (Result = 0 or else Result = ENOMEM);
 353
 354       if Result = ENOMEM then
 355          raise Storage_Error;
 356       end if;
 357
 358       if Locking_Policy = 'C' then
 359          Result := pthread_mutexattr_setprotocol
 360            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 361          pragma Assert (Result = 0);
 362
 363          Result := pthread_mutexattr_setprioceiling
 364             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 365          pragma Assert (Result = 0);
 366
 367       elsif Locking_Policy = 'I' then
 368          Result := pthread_mutexattr_setprotocol
 369            (Attributes'Access, PTHREAD_PRIO_INHERIT);
 370          pragma Assert (Result = 0);
 371       end if;
 372
 373       Result := pthread_mutex_init (L, Attributes'Access);
 374       pragma Assert (Result = 0 or else Result = ENOMEM);
 375
 376       if Result = ENOMEM then
 377          Result := pthread_mutexattr_destroy (Attributes'Access);
 378          raise Storage_Error;
 379       end if;
 380
 381       Result := pthread_mutexattr_destroy (Attributes'Access);
 382       pragma Assert (Result = 0);
 383    end Initialize_Lock;
 384
 385    -------------------
 386    -- Finalize_Lock --
 387    -------------------
 388
 389    procedure Finalize_Lock (L : access Lock) is
 390       Result : Interfaces.C.int;
 391
 392    begin
 393       Result := pthread_mutex_destroy (L);
 394       pragma Assert (Result = 0);
 395    end Finalize_Lock;
 396
 397    procedure Finalize_Lock (L : access RTS_Lock) is
 398       Result : Interfaces.C.int;
 399
 400    begin
 401       Result := pthread_mutex_destroy (L);
 402       pragma Assert (Result = 0);
 403    end Finalize_Lock;
 404
 405    ----------------
 406    -- Write_Lock --
 407    ----------------
 408
 409    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 410       Result : Interfaces.C.int;
 411
 412    begin
 413       Result := pthread_mutex_lock (L);
 414
 415       --  Assume that the cause of EINVAL is a priority ceiling violation
 416
 417       Ceiling_Violation := (Result = EINVAL);
 418       pragma Assert (Result = 0 or else Result = EINVAL);
 419    end Write_Lock;
 420
 421    procedure Write_Lock
 422      (L           : access RTS_Lock;
 423       Global_Lock : Boolean := False)
 424    is
 425       Result : Interfaces.C.int;
 426
 427    begin
 428       if not Single_Lock or else Global_Lock then
 429          Result := pthread_mutex_lock (L);
 430          pragma Assert (Result = 0);
 431       end if;
 432    end Write_Lock;
 433
 434    procedure Write_Lock (T : Task_ID) is
 435       Result : Interfaces.C.int;
 436
 437    begin
 438       if not Single_Lock then
 439          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 440          pragma Assert (Result = 0);
 441       end if;
 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; Global_Lock : Boolean := False) is
 466       Result : Interfaces.C.int;
 467
 468    begin
 469       if not Single_Lock or else Global_Lock then
 470          Result := pthread_mutex_unlock (L);
 471          pragma Assert (Result = 0);
 472       end if;
 473    end Unlock;
 474
 475    procedure Unlock (T : Task_ID) is
 476       Result : Interfaces.C.int;
 477
 478    begin
 479       if not Single_Lock then
 480          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 481          pragma Assert (Result = 0);
 482       end if;
 483    end Unlock;
 484
 485    -----------
 486    -- Sleep --
 487    -----------
 488
 489    procedure Sleep
 490      (Self_ID : Task_ID;
 491       Reason   : System.Tasking.Task_States)
 492    is
 493       pragma Warnings (Off, Reason);
 494
 495       Result : Interfaces.C.int;
 496
 497    begin
 498       if Single_Lock then
 499          Result := pthread_cond_wait
 500            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 501       else
 502          Result := pthread_cond_wait
 503            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 504       end if;
 505
 506       --  EINTR is not considered a failure.
 507
 508       pragma Assert (Result = 0 or else Result = EINTR);
 509    end Sleep;
 510
 511    -----------------
 512    -- Timed_Sleep --
 513    -----------------
 514
 515    --  This is for use within the run-time system, so abort is
 516    --  assumed to be already deferred, and the caller should be
 517    --  holding its own ATCB lock.
 518
 519    procedure Timed_Sleep
 520      (Self_ID  : Task_ID;
 521       Time     : Duration;
 522       Mode     : ST.Delay_Modes;
 523       Reason   : Task_States;
 524       Timedout : out Boolean;
 525       Yielded  : out Boolean)
 526    is
 527       pragma Warnings (Off, Reason);
 528
 529       Check_Time : constant Duration := Monotonic_Clock;
 530       Rel_Time   : Duration;
 531       Abs_Time   : Duration;
 532       Request    : aliased timespec;
 533       Result     : Interfaces.C.int;
 534
 535    begin
 536       Timedout := True;
 537       Yielded := False;
 538
 539       if Mode = Relative then
 540          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 541
 542          if Relative_Timed_Wait then
 543             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 544          end if;
 545
 546       else
 547          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 548
 549          if Relative_Timed_Wait then
 550             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 551          end if;
 552       end if;
 553
 554       if Abs_Time > Check_Time then
 555          if Relative_Timed_Wait then
 556             Request := To_Timespec (Rel_Time);
 557          else
 558             Request := To_Timespec (Abs_Time);
 559          end if;
 560
 561          loop
 562             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 563               or else Self_ID.Pending_Priority_Change;
 564
 565             if Single_Lock then
 566                Result := pthread_cond_timedwait
 567                  (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 568                   Request'Access);
 569
 570             else
 571                Result := pthread_cond_timedwait
 572                  (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 573                   Request'Access);
 574             end if;
 575
 576             exit when Abs_Time <= Monotonic_Clock;
 577
 578             if Result = 0 or Result = EINTR then
 579
 580                --  Somebody may have called Wakeup for us
 581
 582                Timedout := False;
 583                exit;
 584             end if;
 585
 586             pragma Assert (Result = ETIMEDOUT);
 587          end loop;
 588       end if;
 589    end Timed_Sleep;
 590
 591    -----------------
 592    -- Timed_Delay --
 593    -----------------
 594
 595    --  This is for use in implementing delay statements, so
 596    --  we assume the caller is abort-deferred but is holding
 597    --  no locks.
 598
 599    procedure Timed_Delay
 600      (Self_ID  : Task_ID;
 601       Time     : Duration;
 602       Mode     : ST.Delay_Modes)
 603    is
 604       Check_Time : constant Duration := Monotonic_Clock;
 605       Abs_Time   : Duration;
 606       Rel_Time   : Duration;
 607       Request    : aliased timespec;
 608       Result     : Interfaces.C.int;
 609
 610    begin
 611       --  Only the little window between deferring abort and
 612       --  locking Self_ID is the reason we need to
 613       --  check for pending abort and priority change below! :(
 614
 615       SSL.Abort_Defer.all;
 616
 617       if Single_Lock then
 618          Lock_RTS;
 619       end if;
 620
 621       Write_Lock (Self_ID);
 622
 623       if Mode = Relative then
 624          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 625
 626          if Relative_Timed_Wait then
 627             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 628          end if;
 629
 630       else
 631          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 632
 633          if Relative_Timed_Wait then
 634             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 635          end if;
 636       end if;
 637
 638       if Abs_Time > Check_Time then
 639          if Relative_Timed_Wait then
 640             Request := To_Timespec (Rel_Time);
 641          else
 642             Request := To_Timespec (Abs_Time);
 643          end if;
 644
 645          Self_ID.Common.State := Delay_Sleep;
 646
 647          loop
 648             if Self_ID.Pending_Priority_Change then
 649                Self_ID.Pending_Priority_Change := False;
 650                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 651                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 652             end if;
 653
 654             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 655
 656             if Single_Lock then
 657                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 658                  Single_RTS_Lock'Access, Request'Access);
 659             else
 660                Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 661                  Self_ID.Common.LL.L'Access, Request'Access);
 662             end if;
 663
 664             exit when Abs_Time <= Monotonic_Clock;
 665
 666             pragma Assert (Result = 0
 667                              or else Result = ETIMEDOUT
 668                              or else Result = EINTR);
 669          end loop;
 670
 671          Self_ID.Common.State := Runnable;
 672       end if;
 673
 674       Unlock (Self_ID);
 675
 676       if Single_Lock then
 677          Unlock_RTS;
 678       end if;
 679
 680       Result := sched_yield;
 681       SSL.Abort_Undefer.all;
 682    end Timed_Delay;
 683
 684    ---------------------
 685    -- Monotonic_Clock --
 686    ---------------------
 687
 688    function Monotonic_Clock return Duration is
 689       TS     : aliased timespec;
 690       Result : Interfaces.C.int;
 691
 692    begin
 693       Result := clock_gettime
 694         (clock_id => CLOCK_REALTIME, tp => TS'Unchecked_Access);
 695       pragma Assert (Result = 0);
 696       return To_Duration (TS);
 697    end Monotonic_Clock;
 698
 699    -------------------
 700    -- RT_Resolution --
 701    -------------------
 702
 703    function RT_Resolution return Duration is
 704    begin
 705       return 10#1.0#E-6;
 706    end RT_Resolution;
 707
 708    ------------
 709    -- Wakeup --
 710    ------------
 711
 712    procedure Wakeup (T : Task_ID; Reason : System.Tasking.Task_States) is
 713       pragma Warnings (Off, Reason);
 714
 715       Result : Interfaces.C.int;
 716
 717    begin
 718       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 719       pragma Assert (Result = 0);
 720    end Wakeup;
 721
 722    -----------
 723    -- Yield --
 724    -----------
 725
 726    procedure Yield (Do_Yield : Boolean := True) is
 727       Result : Interfaces.C.int;
 728       pragma Unreferenced (Result);
 729    begin
 730       if Do_Yield then
 731          Result := sched_yield;
 732       end if;
 733    end Yield;
 734
 735    ------------------
 736    -- Set_Priority --
 737    ------------------
 738
 739    procedure Set_Priority
 740      (T                   : Task_ID;
 741       Prio                : System.Any_Priority;
 742       Loss_Of_Inheritance : Boolean := False)
 743    is
 744       pragma Warnings (Off, Loss_Of_Inheritance);
 745
 746       Result : Interfaces.C.int;
 747       Param  : aliased struct_sched_param;
 748
 749    begin
 750       T.Common.Current_Priority := Prio;
 751       Param.sched_priority := Interfaces.C.int (Prio);
 752
 753       if Time_Slice_Supported and then Time_Slice_Val > 0 then
 754          Result := pthread_setschedparam
 755            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 756
 757       elsif FIFO_Within_Priorities or else Time_Slice_Val = 0 then
 758          Result := pthread_setschedparam
 759            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 760
 761       else
 762          Result := pthread_setschedparam
 763            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 764       end if;
 765
 766       pragma Assert (Result = 0);
 767    end Set_Priority;
 768
 769    ------------------
 770    -- Get_Priority --
 771    ------------------
 772
 773    function Get_Priority (T : Task_ID) return System.Any_Priority is
 774    begin
 775       return T.Common.Current_Priority;
 776    end Get_Priority;
 777
 778    ----------------
 779    -- Enter_Task --
 780    ----------------
 781
 782    procedure Enter_Task (Self_ID : Task_ID) is
 783    begin
 784       Self_ID.Common.LL.Thread := pthread_self;
 785       Self_ID.Common.LL.LWP := lwp_self;
 786
 787       Specific.Set (Self_ID);
 788
 789       Lock_RTS;
 790
 791       for J in Known_Tasks'Range loop
 792          if Known_Tasks (J) = null then
 793             Known_Tasks (J) := Self_ID;
 794             Self_ID.Known_Tasks_Index := J;
 795             exit;
 796          end if;
 797       end loop;
 798
 799       Unlock_RTS;
 800    end Enter_Task;
 801
 802    --------------
 803    -- New_ATCB --
 804    --------------
 805
 806    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_ID is
 807    begin
 808       return new Ada_Task_Control_Block (Entry_Num);
 809    end New_ATCB;
 810
 811    -------------------
 812    -- Is_Valid_Task --
 813    -------------------
 814
 815    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 816
 817    -----------------------------
 818    -- Register_Foreign_Thread --
 819    -----------------------------
 820
 821    function Register_Foreign_Thread return Task_ID is
 822    begin
 823       if Is_Valid_Task then
 824          return Self;
 825       else
 826          return Register_Foreign_Thread (pthread_self);
 827       end if;
 828    end Register_Foreign_Thread;
 829
 830    --------------------
 831    -- Initialize_TCB --
 832    --------------------
 833
 834    procedure Initialize_TCB (Self_ID : Task_ID; Succeeded : out Boolean) is
 835       Mutex_Attr : aliased pthread_mutexattr_t;
 836       Result     : Interfaces.C.int;
 837       Cond_Attr  : aliased pthread_condattr_t;
 838
 839    begin
 840       --  Give the task a unique serial number.
 841
 842       Self_ID.Serial_Number := Next_Serial_Number;
 843       Next_Serial_Number := Next_Serial_Number + 1;
 844       pragma Assert (Next_Serial_Number /= 0);
 845
 846       if not Single_Lock then
 847          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 848          pragma Assert (Result = 0 or else Result = ENOMEM);
 849
 850          if Result = 0 then
 851             if Locking_Policy = 'C' then
 852                Result := pthread_mutexattr_setprotocol
 853                  (Mutex_Attr'Access, PTHREAD_PRIO_PROTECT);
 854                pragma Assert (Result = 0);
 855
 856                Result := pthread_mutexattr_setprioceiling
 857                   (Mutex_Attr'Access,
 858                    Interfaces.C.int (System.Any_Priority'Last));
 859                pragma Assert (Result = 0);
 860
 861             elsif Locking_Policy = 'I' then
 862                Result := pthread_mutexattr_setprotocol
 863                  (Mutex_Attr'Access, PTHREAD_PRIO_INHERIT);
 864                pragma Assert (Result = 0);
 865             end if;
 866
 867             Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 868               Mutex_Attr'Access);
 869             pragma Assert (Result = 0 or else Result = ENOMEM);
 870          end if;
 871
 872          if Result /= 0 then
 873             Succeeded := False;
 874             return;
 875          end if;
 876
 877          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 878          pragma Assert (Result = 0);
 879       end if;
 880
 881       Result := pthread_condattr_init (Cond_Attr'Access);
 882       pragma Assert (Result = 0 or else Result = ENOMEM);
 883
 884       if Result = 0 then
 885          Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 886            Cond_Attr'Access);
 887          pragma Assert (Result = 0 or else Result = ENOMEM);
 888       end if;
 889
 890       if Result = 0 then
 891          Succeeded := True;
 892       else
 893          if not Single_Lock then
 894             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 895             pragma Assert (Result = 0);
 896          end if;
 897
 898          Succeeded := False;
 899       end if;
 900
 901       Result := pthread_condattr_destroy (Cond_Attr'Access);
 902       pragma Assert (Result = 0);
 903    end Initialize_TCB;
 904
 905    -----------------
 906    -- Create_Task --
 907    -----------------
 908
 909    procedure Create_Task
 910      (T          : Task_ID;
 911       Wrapper    : System.Address;
 912       Stack_Size : System.Parameters.Size_Type;
 913       Priority   : System.Any_Priority;
 914       Succeeded  : out Boolean)
 915    is
 916       Attributes          : aliased pthread_attr_t;
 917       Adjusted_Stack_Size : Interfaces.C.size_t;
 918       Result              : Interfaces.C.int;
 919
 920       function Thread_Body_Access is new
 921         Unchecked_Conversion (System.Address, Thread_Body);
 922
 923       use System.Task_Info;
 924
 925    begin
 926       if Stack_Size = Unspecified_Size then
 927          Adjusted_Stack_Size := Interfaces.C.size_t (Default_Stack_Size);
 928
 929       elsif Stack_Size < Minimum_Stack_Size then
 930          Adjusted_Stack_Size := Interfaces.C.size_t (Minimum_Stack_Size);
 931
 932       else
 933          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 934       end if;
 935
 936       if Stack_Base_Available then
 937          --  If Stack Checking is supported then allocate 2 additional pages:
 938          --
 939          --  In the worst case, stack is allocated at something like
 940          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 941          --  to be sure the effective stack size is greater than what
 942          --  has been asked.
 943
 944          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Get_Page_Size;
 945       end if;
 946
 947       Result := pthread_attr_init (Attributes'Access);
 948       pragma Assert (Result = 0 or else Result = ENOMEM);
 949
 950       if Result /= 0 then
 951          Succeeded := False;
 952          return;
 953       end if;
 954
 955       Result := pthread_attr_setdetachstate
 956         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 957       pragma Assert (Result = 0);
 958
 959       Result := pthread_attr_setstacksize
 960         (Attributes'Access, Adjusted_Stack_Size);
 961       pragma Assert (Result = 0);
 962
 963       if T.Common.Task_Info /= Default_Scope then
 964
 965          --  We are assuming that Scope_Type has the same values than the
 966          --  corresponding C macros
 967
 968          Result := pthread_attr_setscope
 969            (Attributes'Access, Task_Info_Type'Pos (T.Common.Task_Info));
 970          pragma Assert (Result = 0);
 971       end if;
 972
 973       --  Since the initial signal mask of a thread is inherited from the
 974       --  creator, and the Environment task has all its signals masked, we
 975       --  do not need to manipulate caller's signal mask at this point.
 976       --  All tasks in RTS will have All_Tasks_Mask initially.
 977
 978       Result := pthread_create
 979         (T.Common.LL.Thread'Access,
 980          Attributes'Access,
 981          Thread_Body_Access (Wrapper),
 982          To_Address (T));
 983       pragma Assert (Result = 0 or else Result = EAGAIN);
 984
 985       Succeeded := Result = 0;
 986
 987       Result := pthread_attr_destroy (Attributes'Access);
 988       pragma Assert (Result = 0);
 989
 990       Set_Priority (T, Priority);
 991    end Create_Task;
 992
 993    ------------------
 994    -- Finalize_TCB --
 995    ------------------
 996
 997    procedure Finalize_TCB (T : Task_ID) is
 998       Result  : Interfaces.C.int;
 999       Tmp     : Task_ID := T;
1000       Is_Self : constant Boolean := T = Self;
1001
1002       procedure Free is new
1003         Unchecked_Deallocation (Ada_Task_Control_Block, Task_ID);
1004
1005    begin
1006       if not Single_Lock then
1007          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1008          pragma Assert (Result = 0);
1009       end if;
1010
1011       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1012       pragma Assert (Result = 0);
1013
1014       if T.Known_Tasks_Index /= -1 then
1015          Known_Tasks (T.Known_Tasks_Index) := null;
1016       end if;
1017
1018       Free (Tmp);
1019
1020       if Is_Self then
1021          Specific.Set (null);
1022       end if;
1023    end Finalize_TCB;
1024
1025    ---------------
1026    -- Exit_Task --
1027    ---------------
1028
1029    procedure Exit_Task is
1030    begin
1031       --  Mark this task as unknown, so that if Self is called, it won't
1032       --  return a dangling pointer.
1033
1034       Specific.Set (null);
1035    end Exit_Task;
1036
1037    ----------------
1038    -- Abort_Task --
1039    ----------------
1040
1041    procedure Abort_Task (T : Task_ID) is
1042       Result : Interfaces.C.int;
1043
1044    begin
1045       Result := pthread_kill (T.Common.LL.Thread,
1046         Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1047       pragma Assert (Result = 0);
1048    end Abort_Task;
1049
1050    ----------------
1051    -- Check_Exit --
1052    ----------------
1053
1054    --  Dummy version
1055
1056    function Check_Exit (Self_ID : ST.Task_ID) return Boolean is
1057       pragma Warnings (Off, Self_ID);
1058
1059    begin
1060       return True;
1061    end Check_Exit;
1062
1063    --------------------
1064    -- Check_No_Locks --
1065    --------------------
1066
1067    function Check_No_Locks (Self_ID : ST.Task_ID) return Boolean is
1068       pragma Warnings (Off, Self_ID);
1069
1070    begin
1071       return True;
1072    end Check_No_Locks;
1073
1074    ----------------------
1075    -- Environment_Task --
1076    ----------------------
1077
1078    function Environment_Task return Task_ID is
1079    begin
1080       return Environment_Task_ID;
1081    end Environment_Task;
1082
1083    --------------
1084    -- Lock_RTS --
1085    --------------
1086
1087    procedure Lock_RTS is
1088    begin
1089       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1090    end Lock_RTS;
1091
1092    ----------------
1093    -- Unlock_RTS --
1094    ----------------
1095
1096    procedure Unlock_RTS is
1097    begin
1098       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1099    end Unlock_RTS;
1100
1101    ------------------
1102    -- Suspend_Task --
1103    ------------------
1104
1105    function Suspend_Task
1106      (T           : ST.Task_ID;
1107       Thread_Self : Thread_Id)
1108       return        Boolean
1109    is
1110       pragma Warnings (Off, T);
1111       pragma Warnings (Off, Thread_Self);
1112
1113    begin
1114       return False;
1115    end Suspend_Task;
1116
1117    -----------------
1118    -- Resume_Task --
1119    -----------------
1120
1121    function Resume_Task
1122      (T           : ST.Task_ID;
1123       Thread_Self : Thread_Id)
1124       return        Boolean
1125    is
1126       pragma Warnings (Off, T);
1127       pragma Warnings (Off, Thread_Self);
1128
1129    begin
1130       return False;
1131    end Resume_Task;
1132
1133    ----------------
1134    -- Initialize --
1135    ----------------
1136
1137    procedure Initialize (Environment_Task : Task_ID) is
1138       act     : aliased struct_sigaction;
1139       old_act : aliased struct_sigaction;
1140       Tmp_Set : aliased sigset_t;
1141       Result  : Interfaces.C.int;
1142
1143       function State (Int : System.Interrupt_Management.Interrupt_ID)
1144                      return Character;
1145       pragma Import (C, State, "__gnat_get_interrupt_state");
1146       --  Get interrupt state.  Defined in a-init.c
1147       --  The input argument is the interrupt number,
1148       --  and the result is one of the following:
1149
1150       Default : constant Character := 's';
1151       --    'n'   this interrupt not set by any Interrupt_State pragma
1152       --    'u'   Interrupt_State pragma set state to User
1153       --    'r'   Interrupt_State pragma set state to Runtime
1154       --    's'   Interrupt_State pragma set state to System (use "default"
1155       --           system handler)
1156
1157    begin
1158       Environment_Task_ID := Environment_Task;
1159
1160       --  Initialize the lock used to synchronize chain of all ATCBs.
1161
1162       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1163
1164       Specific.Initialize (Environment_Task);
1165
1166       Enter_Task (Environment_Task);
1167
1168       --  Install the abort-signal handler
1169
1170       if State (System.Interrupt_Management.Abort_Task_Interrupt)
1171         /= Default
1172       then
1173          act.sa_flags := 0;
1174          act.sa_handler := Abort_Handler'Address;
1175
1176          Result := sigemptyset (Tmp_Set'Access);
1177          pragma Assert (Result = 0);
1178          act.sa_mask := Tmp_Set;
1179
1180          Result :=
1181            sigaction
1182            (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1183             act'Unchecked_Access,
1184             old_act'Unchecked_Access);
1185          pragma Assert (Result = 0);
1186       end if;
1187    end Initialize;
1188
1189 begin
1190    declare
1191       Result : Interfaces.C.int;
1192    begin
1193       --  Mask Environment task for all signals. The original mask of the
1194       --  Environment task will be recovered by Interrupt_Server task
1195       --  during the elaboration of s-interr.adb.
1196
1197       System.Interrupt_Management.Operations.Set_Interrupt_Mask
1198         (System.Interrupt_Management.Operations.All_Tasks_Mask'Access);
1199
1200       --  Prepare the set of signals that should unblocked in all tasks
1201
1202       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1203       pragma Assert (Result = 0);
1204
1205       for J in Interrupt_Management.Interrupt_ID loop
1206          if System.Interrupt_Management.Keep_Unmasked (J) then
1207             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1208             pragma Assert (Result = 0);
1209          end if;
1210       end loop;
1211    end;
1212 end System.Task_Primitives.Operations;