gcc/ada/s-taprop-linux.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) 1992-2007, 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 GNU/Linux (GNU/LinuxThreads) version of this package
  35
  36 --  This package contains all the GNULL primitives that interface directly
  37 --  with the underlying OS.
  38
  39 pragma Polling (Off);
  40 --  Turn off polling, we do not want ATC polling to take place during
  41 --  tasking operations. It causes infinite loops and other problems.
  42
  43 with Interfaces.C;
  44 --  used for int
  45 --           size_t
  46
  47 with System.Tasking.Debug;
  48 --  used for Known_Tasks
  49
  50 with System.Interrupt_Management;
  51 --  used for Keep_Unmasked
  52 --           Abort_Task_Interrupt
  53 --           Interrupt_ID
  54
  55 with System.OS_Primitives;
  56 --  used for Delay_Modes
  57
  58 with System.Soft_Links;
  59 --  used for Abort_Defer/Undefer
  60
  61 --  We use System.Soft_Links instead of System.Tasking.Initialization
  62 --  because the later is a higher level package that we shouldn't depend on.
  63 --  For example when using the restricted run time, it is replaced by
  64 --  System.Tasking.Restricted.Stages.
  65
  66 with System.Storage_Elements;
  67 with System.Stack_Checking.Operations;
  68 --  Used for Invalidate_Stack_Cache and Notify_Stack_Attributes;
  69
  70 with Ada.Exceptions;
  71 --  used for Raise_Exception
  72 --           Raise_From_Signal_Handler
  73 --           Exception_Id
  74
  75 with Ada.Unchecked_Conversion;
  76 with Ada.Unchecked_Deallocation;
  77
  78 package body System.Task_Primitives.Operations is
  79
  80    package SSL renames System.Soft_Links;
  81    package SC renames System.Stack_Checking.Operations;
  82
  83    use System.Tasking.Debug;
  84    use System.Tasking;
  85    use Interfaces.C;
  86    use System.OS_Interface;
  87    use System.Parameters;
  88    use System.OS_Primitives;
  89    use System.Storage_Elements;
  90
  91    ----------------
  92    -- Local Data --
  93    ----------------
  94
  95    --  The followings are logically constants, but need to be initialized
  96    --  at run time.
  97
  98    Single_RTS_Lock : aliased RTS_Lock;
  99    --  This is a lock to allow only one thread of control in the RTS at
 100    --  a time; it is used to execute in mutual exclusion from all other tasks.
 101    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 102
 103    ATCB_Key : aliased pthread_key_t;
 104    --  Key used to find the Ada Task_Id associated with a thread
 105
 106    Environment_Task_Id : Task_Id;
 107    --  A variable to hold Task_Id for the environment task
 108
 109    Unblocked_Signal_Mask : aliased sigset_t;
 110    --  The set of signals that should be unblocked in all tasks
 111
 112    --  The followings are internal configuration constants needed
 113
 114    Next_Serial_Number : Task_Serial_Number := 100;
 115    --  We start at 100 (reserve some special values for using in error checks)
 116
 117    Time_Slice_Val : Integer;
 118    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 119
 120    Dispatching_Policy : Character;
 121    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 122
 123    --  The following are effectively constants, but they need to be initialized
 124    --  by calling a pthread_ function.
 125
 126    Mutex_Attr   : aliased pthread_mutexattr_t;
 127    Cond_Attr    : aliased pthread_condattr_t;
 128
 129    Foreign_Task_Elaborated : aliased Boolean := True;
 130    --  Used to identified fake tasks (i.e., non-Ada Threads)
 131
 132    --------------------
 133    -- Local Packages --
 134    --------------------
 135
 136    package Specific is
 137
 138       procedure Initialize (Environment_Task : Task_Id);
 139       pragma Inline (Initialize);
 140       --  Initialize various data needed by this package
 141
 142       function Is_Valid_Task return Boolean;
 143       pragma Inline (Is_Valid_Task);
 144       --  Does executing thread have a TCB?
 145
 146       procedure Set (Self_Id : Task_Id);
 147       pragma Inline (Set);
 148       --  Set the self id for the current task
 149
 150       function Self return Task_Id;
 151       pragma Inline (Self);
 152       --  Return a pointer to the Ada Task Control Block of the calling task
 153
 154    end Specific;
 155
 156    package body Specific is separate;
 157    --  The body of this package is target specific
 158
 159    ---------------------------------
 160    -- Support for foreign threads --
 161    ---------------------------------
 162
 163    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 164    --  Allocate and Initialize a new ATCB for the current Thread
 165
 166    function Register_Foreign_Thread
 167      (Thread : Thread_Id) return Task_Id is separate;
 168
 169    -----------------------
 170    -- Local Subprograms --
 171    -----------------------
 172
 173    subtype unsigned_long is Interfaces.C.unsigned_long;
 174
 175    procedure Abort_Handler (signo : Signal);
 176
 177    function To_pthread_t is new Ada.Unchecked_Conversion
 178      (unsigned_long, System.OS_Interface.pthread_t);
 179
 180    procedure Get_Stack_Attributes
 181      (T    : Task_Id;
 182       ISP  : out System.Address;
 183       Size : out Storage_Offset);
 184    --  Fill ISP and Size with the Initial Stack Pointer value and the
 185    --  thread stack size for task T.
 186
 187    -------------------
 188    -- Abort_Handler --
 189    -------------------
 190
 191    procedure Abort_Handler (signo : Signal) is
 192       pragma Unreferenced (signo);
 193
 194       Self_Id : constant Task_Id := Self;
 195       Result  : Interfaces.C.int;
 196       Old_Set : aliased sigset_t;
 197
 198    begin
 199       if ZCX_By_Default and then GCC_ZCX_Support then
 200          return;
 201       end if;
 202
 203       if Self_Id.Deferral_Level = 0
 204         and then Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level
 205         and then not Self_Id.Aborting
 206       then
 207          Self_Id.Aborting := True;
 208
 209          --  Make sure signals used for RTS internal purpose are unmasked
 210
 211          Result :=
 212            pthread_sigmask
 213              (SIG_UNBLOCK,
 214               Unblocked_Signal_Mask'Access,
 215               Old_Set'Access);
 216          pragma Assert (Result = 0);
 217
 218          raise Standard'Abort_Signal;
 219       end if;
 220    end Abort_Handler;
 221
 222    --------------
 223    -- Lock_RTS --
 224    --------------
 225
 226    procedure Lock_RTS is
 227    begin
 228       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
 229    end Lock_RTS;
 230
 231    ----------------
 232    -- Unlock_RTS --
 233    ----------------
 234
 235    procedure Unlock_RTS is
 236    begin
 237       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
 238    end Unlock_RTS;
 239
 240    -----------------
 241    -- Stack_Guard --
 242    -----------------
 243
 244    --  The underlying thread system extends the memory (up to 2MB) when needed
 245
 246    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 247       pragma Unreferenced (T);
 248       pragma Unreferenced (On);
 249    begin
 250       null;
 251    end Stack_Guard;
 252
 253    --------------------
 254    -- Get_Thread_Id  --
 255    --------------------
 256
 257    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 258    begin
 259       return T.Common.LL.Thread;
 260    end Get_Thread_Id;
 261
 262    ----------
 263    -- Self --
 264    ----------
 265
 266    function Self return Task_Id renames Specific.Self;
 267
 268    ---------------------
 269    -- Initialize_Lock --
 270    ---------------------
 271
 272    --  Note: mutexes and cond_variables needed per-task basis are
 273    --  initialized in Initialize_TCB and the Storage_Error is
 274    --  handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 275    --  used in RTS is initialized before any status change of RTS.
 276    --  Therefore rasing Storage_Error in the following routines
 277    --  should be able to be handled safely.
 278
 279    procedure Initialize_Lock
 280      (Prio : System.Any_Priority;
 281       L    : not null access Lock)
 282    is
 283       pragma Unreferenced (Prio);
 284
 285       Result : Interfaces.C.int;
 286
 287    begin
 288       Result := pthread_mutex_init (L, Mutex_Attr'Access);
 289
 290       pragma Assert (Result = 0 or else Result = ENOMEM);
 291
 292       if Result = ENOMEM then
 293          Ada.Exceptions.Raise_Exception (Storage_Error'Identity,
 294            "Failed to allocate a lock");
 295       end if;
 296    end Initialize_Lock;
 297
 298    procedure Initialize_Lock
 299      (L     : not null access RTS_Lock;
 300       Level : Lock_Level)
 301    is
 302       pragma Unreferenced (Level);
 303
 304       Result : Interfaces.C.int;
 305
 306    begin
 307       Result := pthread_mutex_init (L, Mutex_Attr'Access);
 308
 309       pragma Assert (Result = 0 or else Result = ENOMEM);
 310
 311       if Result = ENOMEM then
 312          raise Storage_Error;
 313       end if;
 314    end Initialize_Lock;
 315
 316    -------------------
 317    -- Finalize_Lock --
 318    -------------------
 319
 320    procedure Finalize_Lock (L : not null access Lock) is
 321       Result : Interfaces.C.int;
 322    begin
 323       Result := pthread_mutex_destroy (L);
 324       pragma Assert (Result = 0);
 325    end Finalize_Lock;
 326
 327    procedure Finalize_Lock (L : not null access RTS_Lock) is
 328       Result : Interfaces.C.int;
 329    begin
 330       Result := pthread_mutex_destroy (L);
 331       pragma Assert (Result = 0);
 332    end Finalize_Lock;
 333
 334    ----------------
 335    -- Write_Lock --
 336    ----------------
 337
 338    procedure Write_Lock
 339      (L                 : not null access Lock;
 340       Ceiling_Violation : out Boolean)
 341    is
 342       Result : Interfaces.C.int;
 343    begin
 344       Result := pthread_mutex_lock (L);
 345       Ceiling_Violation := Result = EINVAL;
 346
 347       --  Assume the cause of EINVAL is a priority ceiling violation
 348
 349       pragma Assert (Result = 0 or else Result = EINVAL);
 350    end Write_Lock;
 351
 352    procedure Write_Lock
 353      (L           : not null access RTS_Lock;
 354       Global_Lock : Boolean := False)
 355    is
 356       Result : Interfaces.C.int;
 357    begin
 358       if not Single_Lock or else Global_Lock then
 359          Result := pthread_mutex_lock (L);
 360          pragma Assert (Result = 0);
 361       end if;
 362    end Write_Lock;
 363
 364    procedure Write_Lock (T : Task_Id) is
 365       Result : Interfaces.C.int;
 366    begin
 367       if not Single_Lock then
 368          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 369          pragma Assert (Result = 0);
 370       end if;
 371    end Write_Lock;
 372
 373    ---------------
 374    -- Read_Lock --
 375    ---------------
 376
 377    procedure Read_Lock
 378      (L                 : not null access Lock;
 379       Ceiling_Violation : out Boolean)
 380    is
 381    begin
 382       Write_Lock (L, Ceiling_Violation);
 383    end Read_Lock;
 384
 385    ------------
 386    -- Unlock --
 387    ------------
 388
 389    procedure Unlock (L : not null access Lock) is
 390       Result : Interfaces.C.int;
 391    begin
 392       Result := pthread_mutex_unlock (L);
 393       pragma Assert (Result = 0);
 394    end Unlock;
 395
 396    procedure Unlock
 397      (L           : not null access RTS_Lock;
 398       Global_Lock : Boolean := False)
 399    is
 400       Result : Interfaces.C.int;
 401    begin
 402       if not Single_Lock or else Global_Lock then
 403          Result := pthread_mutex_unlock (L);
 404          pragma Assert (Result = 0);
 405       end if;
 406    end Unlock;
 407
 408    procedure Unlock (T : Task_Id) is
 409       Result : Interfaces.C.int;
 410    begin
 411       if not Single_Lock then
 412          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 413          pragma Assert (Result = 0);
 414       end if;
 415    end Unlock;
 416
 417    -----------------
 418    -- Set_Ceiling --
 419    -----------------
 420
 421    --  Dynamic priority ceilings are not supported by the underlying system
 422
 423    procedure Set_Ceiling
 424      (L    : not null access Lock;
 425       Prio : System.Any_Priority)
 426    is
 427       pragma Unreferenced (L, Prio);
 428    begin
 429       null;
 430    end Set_Ceiling;
 431
 432    -----------
 433    -- Sleep --
 434    -----------
 435
 436    procedure Sleep
 437      (Self_ID  : Task_Id;
 438       Reason   : System.Tasking.Task_States)
 439    is
 440       pragma Unreferenced (Reason);
 441
 442       Result : Interfaces.C.int;
 443
 444    begin
 445       pragma Assert (Self_ID = Self);
 446
 447       if Single_Lock then
 448          Result :=
 449            pthread_cond_wait
 450              (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 451       else
 452          Result :=
 453            pthread_cond_wait
 454              (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 455       end if;
 456
 457       --  EINTR is not considered a failure
 458
 459       pragma Assert (Result = 0 or else Result = EINTR);
 460    end Sleep;
 461
 462    -----------------
 463    -- Timed_Sleep --
 464    -----------------
 465
 466    --  This is for use within the run-time system, so abort is
 467    --  assumed to be already deferred, and the caller should be
 468    --  holding its own ATCB lock.
 469
 470    procedure Timed_Sleep
 471      (Self_ID  : Task_Id;
 472       Time     : Duration;
 473       Mode     : ST.Delay_Modes;
 474       Reason   : System.Tasking.Task_States;
 475       Timedout : out Boolean;
 476       Yielded  : out Boolean)
 477    is
 478       pragma Unreferenced (Reason);
 479
 480       Base_Time  : constant Duration := Monotonic_Clock;
 481       Check_Time : Duration := Base_Time;
 482       Abs_Time   : Duration;
 483       Request    : aliased timespec;
 484       Result     : Interfaces.C.int;
 485
 486    begin
 487       Timedout := True;
 488       Yielded := False;
 489
 490       if Mode = Relative then
 491          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 492       else
 493          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 494       end if;
 495
 496       if Abs_Time > Check_Time then
 497          Request := To_Timespec (Abs_Time);
 498
 499          loop
 500             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 501
 502             if Single_Lock then
 503                Result :=
 504                  pthread_cond_timedwait
 505                    (Self_ID.Common.LL.CV'Access,
 506                     Single_RTS_Lock'Access,
 507                     Request'Access);
 508
 509             else
 510                Result :=
 511                  pthread_cond_timedwait
 512                    (Self_ID.Common.LL.CV'Access,
 513                     Self_ID.Common.LL.L'Access,
 514                     Request'Access);
 515             end if;
 516
 517             Check_Time := Monotonic_Clock;
 518             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 519
 520             if Result = 0 or else Result = EINTR then
 521
 522                --  Somebody may have called Wakeup for us
 523
 524                Timedout := False;
 525                exit;
 526             end if;
 527
 528             pragma Assert (Result = ETIMEDOUT);
 529          end loop;
 530       end if;
 531    end Timed_Sleep;
 532
 533    -----------------
 534    -- Timed_Delay --
 535    -----------------
 536
 537    --  This is for use in implementing delay statements, so we assume the
 538    --  caller is abort-deferred but is holding no locks.
 539
 540    procedure Timed_Delay
 541      (Self_ID : Task_Id;
 542       Time    : Duration;
 543       Mode    : ST.Delay_Modes)
 544    is
 545       Base_Time  : constant Duration := Monotonic_Clock;
 546       Check_Time : Duration := Base_Time;
 547       Abs_Time   : Duration;
 548       Request    : aliased timespec;
 549
 550       Result : Interfaces.C.int;
 551       pragma Warnings (Off, Result);
 552
 553    begin
 554       if Single_Lock then
 555          Lock_RTS;
 556       end if;
 557
 558       Write_Lock (Self_ID);
 559
 560       if Mode = Relative then
 561          Abs_Time := Time + Check_Time;
 562       else
 563          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 564       end if;
 565
 566       if Abs_Time > Check_Time then
 567          Request := To_Timespec (Abs_Time);
 568          Self_ID.Common.State := Delay_Sleep;
 569
 570          loop
 571             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 572
 573             if Single_Lock then
 574                Result := pthread_cond_timedwait
 575                            (Self_ID.Common.LL.CV'Access,
 576                             Single_RTS_Lock'Access,
 577                             Request'Access);
 578             else
 579                Result := pthread_cond_timedwait
 580                            (Self_ID.Common.LL.CV'Access,
 581                             Self_ID.Common.LL.L'Access,
 582                             Request'Access);
 583             end if;
 584
 585             Check_Time := Monotonic_Clock;
 586             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 587
 588             pragma Assert (Result = 0 or else
 589               Result = ETIMEDOUT or else
 590               Result = EINTR);
 591          end loop;
 592
 593          Self_ID.Common.State := Runnable;
 594       end if;
 595
 596       Unlock (Self_ID);
 597
 598       if Single_Lock then
 599          Unlock_RTS;
 600       end if;
 601
 602       Result := sched_yield;
 603    end Timed_Delay;
 604
 605    ---------------------
 606    -- Monotonic_Clock --
 607    ---------------------
 608
 609    function Monotonic_Clock return Duration is
 610       TV     : aliased struct_timeval;
 611       Result : Interfaces.C.int;
 612    begin
 613       Result := gettimeofday (TV'Access, System.Null_Address);
 614       pragma Assert (Result = 0);
 615       return To_Duration (TV);
 616    end Monotonic_Clock;
 617
 618    -------------------
 619    -- RT_Resolution --
 620    -------------------
 621
 622    function RT_Resolution return Duration is
 623    begin
 624       return 10#1.0#E-6;
 625    end RT_Resolution;
 626
 627    ------------
 628    -- Wakeup --
 629    ------------
 630
 631    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 632       pragma Unreferenced (Reason);
 633       Result : Interfaces.C.int;
 634    begin
 635       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 636       pragma Assert (Result = 0);
 637    end Wakeup;
 638
 639    -----------
 640    -- Yield --
 641    -----------
 642
 643    procedure Yield (Do_Yield : Boolean := True) is
 644       Result : Interfaces.C.int;
 645       pragma Unreferenced (Result);
 646    begin
 647       if Do_Yield then
 648          Result := sched_yield;
 649       end if;
 650    end Yield;
 651
 652    ------------------
 653    -- Set_Priority --
 654    ------------------
 655
 656    procedure Set_Priority
 657      (T                   : Task_Id;
 658       Prio                : System.Any_Priority;
 659       Loss_Of_Inheritance : Boolean := False)
 660    is
 661       pragma Unreferenced (Loss_Of_Inheritance);
 662
 663       Result : Interfaces.C.int;
 664       Param  : aliased struct_sched_param;
 665
 666       function Get_Policy (Prio : System.Any_Priority) return Character;
 667       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 668       --  Get priority specific dispatching policy
 669
 670       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 671       --  Upper case first character of the policy name corresponding to the
 672       --  task as set by a Priority_Specific_Dispatching pragma.
 673
 674    begin
 675       T.Common.Current_Priority := Prio;
 676
 677       --  Priorities are 1 .. 99 on GNU/Linux, so we map 0 .. 98 to 1 .. 99
 678
 679       Param.sched_priority := Interfaces.C.int (Prio) + 1;
 680
 681       if Dispatching_Policy = 'R'
 682         or else Priority_Specific_Policy = 'R'
 683         or else Time_Slice_Val > 0
 684       then
 685          Result :=
 686            pthread_setschedparam
 687              (T.Common.LL.Thread, SCHED_RR, Param'Access);
 688
 689       elsif Dispatching_Policy = 'F'
 690         or else Priority_Specific_Policy = 'F'
 691         or else Time_Slice_Val = 0
 692       then
 693          Result :=
 694            pthread_setschedparam
 695              (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 696
 697       else
 698          Param.sched_priority := 0;
 699          Result :=
 700            pthread_setschedparam
 701              (T.Common.LL.Thread,
 702               SCHED_OTHER, Param'Access);
 703       end if;
 704
 705       pragma Assert (Result = 0 or else Result = EPERM);
 706    end Set_Priority;
 707
 708    ------------------
 709    -- Get_Priority --
 710    ------------------
 711
 712    function Get_Priority (T : Task_Id) return System.Any_Priority is
 713    begin
 714       return T.Common.Current_Priority;
 715    end Get_Priority;
 716
 717    --------------------------
 718    -- Get_Stack_Attributes --
 719    --------------------------
 720
 721    procedure Get_Stack_Attributes
 722      (T    : Task_Id;
 723       ISP  : out System.Address;
 724       Size : out Storage_Offset)
 725    is
 726       function pthread_getattr_np
 727         (thread : pthread_t;
 728          attr   : System.Address) return Interfaces.C.int;
 729       pragma Import (C, pthread_getattr_np, "pthread_getattr_np");
 730
 731       function pthread_attr_getstack
 732         (attr : System.Address;
 733          base : System.Address;
 734          size : System.Address) return Interfaces.C.int;
 735       pragma Import (C, pthread_attr_getstack, "pthread_attr_getstack");
 736
 737       Result : Interfaces.C.int;
 738
 739       Attributes : aliased pthread_attr_t;
 740       Stack_Base : aliased System.Address;
 741       Stack_Size : aliased Storage_Offset;
 742
 743    begin
 744       Result :=
 745         pthread_getattr_np
 746           (T.Common.LL.Thread, Attributes'Address);
 747       pragma Assert (Result = 0);
 748
 749       Result :=
 750         pthread_attr_getstack
 751           (Attributes'Address, Stack_Base'Address, Stack_Size'Address);
 752       pragma Assert (Result = 0);
 753
 754       Result := pthread_attr_destroy (Attributes'Access);
 755       pragma Assert (Result = 0);
 756
 757       ISP  := Stack_Base + Stack_Size;
 758       Size := Stack_Size;
 759    end Get_Stack_Attributes;
 760
 761    ----------------
 762    -- Enter_Task --
 763    ----------------
 764
 765    procedure Enter_Task (Self_ID : Task_Id) is
 766    begin
 767       Self_ID.Common.LL.Thread := pthread_self;
 768
 769       Specific.Set (Self_ID);
 770
 771       Lock_RTS;
 772
 773       for J in Known_Tasks'Range loop
 774          if Known_Tasks (J) = null then
 775             Known_Tasks (J) := Self_ID;
 776             Self_ID.Known_Tasks_Index := J;
 777             exit;
 778          end if;
 779       end loop;
 780
 781       Unlock_RTS;
 782
 783       --  Determine where the task stack starts, how large it is, and let the
 784       --  stack checking engine know about it.
 785
 786       declare
 787          Initial_SP : System.Address;
 788          Stack_Size : Storage_Offset;
 789       begin
 790          Get_Stack_Attributes (Self_ID, Initial_SP, Stack_Size);
 791          System.Stack_Checking.Operations.Notify_Stack_Attributes
 792            (Initial_SP, Stack_Size);
 793       end;
 794    end Enter_Task;
 795
 796    --------------
 797    -- New_ATCB --
 798    --------------
 799
 800    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 801    begin
 802       return new Ada_Task_Control_Block (Entry_Num);
 803    end New_ATCB;
 804
 805    -------------------
 806    -- Is_Valid_Task --
 807    -------------------
 808
 809    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 810
 811    -----------------------------
 812    -- Register_Foreign_Thread --
 813    -----------------------------
 814
 815    function Register_Foreign_Thread return Task_Id is
 816    begin
 817       if Is_Valid_Task then
 818          return Self;
 819       else
 820          return Register_Foreign_Thread (pthread_self);
 821       end if;
 822    end Register_Foreign_Thread;
 823
 824    --------------------
 825    -- Initialize_TCB --
 826    --------------------
 827
 828    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 829       Result : Interfaces.C.int;
 830
 831    begin
 832       --  Give the task a unique serial number
 833
 834       Self_ID.Serial_Number := Next_Serial_Number;
 835       Next_Serial_Number := Next_Serial_Number + 1;
 836       pragma Assert (Next_Serial_Number /= 0);
 837
 838       Self_ID.Common.LL.Thread := To_pthread_t (-1);
 839
 840       if not Single_Lock then
 841          Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 842            Mutex_Attr'Access);
 843          pragma Assert (Result = 0 or else Result = ENOMEM);
 844
 845          if Result /= 0 then
 846             Succeeded := False;
 847             return;
 848          end if;
 849       end if;
 850
 851       Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 852         Cond_Attr'Access);
 853       pragma Assert (Result = 0 or else Result = ENOMEM);
 854
 855       if Result = 0 then
 856          Succeeded := True;
 857       else
 858          if not Single_Lock then
 859             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 860             pragma Assert (Result = 0);
 861          end if;
 862
 863          Succeeded := False;
 864       end if;
 865    end Initialize_TCB;
 866
 867    -----------------
 868    -- Create_Task --
 869    -----------------
 870
 871    procedure Create_Task
 872      (T          : Task_Id;
 873       Wrapper    : System.Address;
 874       Stack_Size : System.Parameters.Size_Type;
 875       Priority   : System.Any_Priority;
 876       Succeeded  : out Boolean)
 877    is
 878       Attributes : aliased pthread_attr_t;
 879       Result     : Interfaces.C.int;
 880
 881    begin
 882       Result := pthread_attr_init (Attributes'Access);
 883       pragma Assert (Result = 0 or else Result = ENOMEM);
 884
 885       if Result /= 0 then
 886          Succeeded := False;
 887          return;
 888       end if;
 889
 890       Result :=
 891         pthread_attr_setstacksize
 892           (Attributes'Access, Interfaces.C.size_t (Stack_Size));
 893       pragma Assert (Result = 0);
 894
 895       Result :=
 896         pthread_attr_setdetachstate
 897           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 898       pragma Assert (Result = 0);
 899
 900       --  Since the initial signal mask of a thread is inherited from the
 901       --  creator, and the Environment task has all its signals masked, we
 902       --  do not need to manipulate caller's signal mask at this point.
 903       --  All tasks in RTS will have All_Tasks_Mask initially.
 904
 905       Result := pthread_create
 906         (T.Common.LL.Thread'Access,
 907          Attributes'Access,
 908          Thread_Body_Access (Wrapper),
 909          To_Address (T));
 910       pragma Assert (Result = 0 or else Result = EAGAIN);
 911
 912       Succeeded := Result = 0;
 913
 914       Result := pthread_attr_destroy (Attributes'Access);
 915       pragma Assert (Result = 0);
 916
 917       Set_Priority (T, Priority);
 918    end Create_Task;
 919
 920    ------------------
 921    -- Finalize_TCB --
 922    ------------------
 923
 924    procedure Finalize_TCB (T : Task_Id) is
 925       Result  : Interfaces.C.int;
 926       Tmp     : Task_Id := T;
 927       Is_Self : constant Boolean := T = Self;
 928
 929       procedure Free is new
 930         Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 931
 932    begin
 933       if not Single_Lock then
 934          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 935          pragma Assert (Result = 0);
 936       end if;
 937
 938       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 939       pragma Assert (Result = 0);
 940
 941       if T.Known_Tasks_Index /= -1 then
 942          Known_Tasks (T.Known_Tasks_Index) := null;
 943       end if;
 944       SC.Invalidate_Stack_Cache (T.Common.Compiler_Data.Pri_Stack_Info'Access);
 945       Free (Tmp);
 946
 947       if Is_Self then
 948          Specific.Set (null);
 949       end if;
 950    end Finalize_TCB;
 951
 952    ---------------
 953    -- Exit_Task --
 954    ---------------
 955
 956    procedure Exit_Task is
 957    begin
 958       Specific.Set (null);
 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    begin
 968       Result :=
 969         pthread_kill
 970           (T.Common.LL.Thread,
 971            Signal (System.Interrupt_Management.Abort_Task_Interrupt));
 972       pragma Assert (Result = 0);
 973    end Abort_Task;
 974
 975    ----------------
 976    -- Initialize --
 977    ----------------
 978
 979    procedure Initialize (S : in out Suspension_Object) is
 980       Result : Interfaces.C.int;
 981
 982    begin
 983       --  Initialize internal state (always to False (RM D.10(6)))
 984
 985       S.State := False;
 986       S.Waiting := False;
 987
 988       --  Initialize internal mutex
 989
 990       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
 991
 992       pragma Assert (Result = 0 or else Result = ENOMEM);
 993
 994       if Result = ENOMEM then
 995          raise Storage_Error;
 996       end if;
 997
 998       --  Initialize internal condition variable
 999
1000       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1001
1002       pragma Assert (Result = 0 or else Result = ENOMEM);
1003
1004       if Result /= 0 then
1005          Result := pthread_mutex_destroy (S.L'Access);
1006          pragma Assert (Result = 0);
1007
1008          if Result = ENOMEM then
1009             raise Storage_Error;
1010          end if;
1011       end if;
1012    end Initialize;
1013
1014    --------------
1015    -- Finalize --
1016    --------------
1017
1018    procedure Finalize (S : in out Suspension_Object) is
1019       Result : Interfaces.C.int;
1020
1021    begin
1022       --  Destroy internal mutex
1023
1024       Result := pthread_mutex_destroy (S.L'Access);
1025       pragma Assert (Result = 0);
1026
1027       --  Destroy internal condition variable
1028
1029       Result := pthread_cond_destroy (S.CV'Access);
1030       pragma Assert (Result = 0);
1031    end Finalize;
1032
1033    -------------------
1034    -- Current_State --
1035    -------------------
1036
1037    function Current_State (S : Suspension_Object) return Boolean is
1038    begin
1039       --  We do not want to use lock on this read operation. State is marked
1040       --  as Atomic so that we ensure that the value retrieved is correct.
1041
1042       return S.State;
1043    end Current_State;
1044
1045    ---------------
1046    -- Set_False --
1047    ---------------
1048
1049    procedure Set_False (S : in out Suspension_Object) is
1050       Result : Interfaces.C.int;
1051
1052    begin
1053       SSL.Abort_Defer.all;
1054
1055       Result := pthread_mutex_lock (S.L'Access);
1056       pragma Assert (Result = 0);
1057
1058       S.State := False;
1059
1060       Result := pthread_mutex_unlock (S.L'Access);
1061       pragma Assert (Result = 0);
1062
1063       SSL.Abort_Undefer.all;
1064    end Set_False;
1065
1066    --------------
1067    -- Set_True --
1068    --------------
1069
1070    procedure Set_True (S : in out Suspension_Object) is
1071       Result : Interfaces.C.int;
1072
1073    begin
1074       SSL.Abort_Defer.all;
1075
1076       Result := pthread_mutex_lock (S.L'Access);
1077       pragma Assert (Result = 0);
1078
1079       --  If there is already a task waiting on this suspension object then
1080       --  we resume it, leaving the state of the suspension object to False,
1081       --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
1082       --  the state to True.
1083
1084       if S.Waiting then
1085          S.Waiting := False;
1086          S.State := False;
1087
1088          Result := pthread_cond_signal (S.CV'Access);
1089          pragma Assert (Result = 0);
1090
1091       else
1092          S.State := True;
1093       end if;
1094
1095       Result := pthread_mutex_unlock (S.L'Access);
1096       pragma Assert (Result = 0);
1097
1098       SSL.Abort_Undefer.all;
1099    end Set_True;
1100
1101    ------------------------
1102    -- Suspend_Until_True --
1103    ------------------------
1104
1105    procedure Suspend_Until_True (S : in out Suspension_Object) is
1106       Result : Interfaces.C.int;
1107
1108    begin
1109       SSL.Abort_Defer.all;
1110
1111       Result := pthread_mutex_lock (S.L'Access);
1112       pragma Assert (Result = 0);
1113
1114       if S.Waiting then
1115
1116          --  Program_Error must be raised upon calling Suspend_Until_True
1117          --  if another task is already waiting on that suspension object
1118          --  (RM D.10(10)).
1119
1120          Result := pthread_mutex_unlock (S.L'Access);
1121          pragma Assert (Result = 0);
1122
1123          SSL.Abort_Undefer.all;
1124
1125          raise Program_Error;
1126       else
1127          --  Suspend the task if the state is False. Otherwise, the task
1128          --  continues its execution, and the state of the suspension object
1129          --  is set to False (ARM D.10 par. 9).
1130
1131          if S.State then
1132             S.State := False;
1133          else
1134             S.Waiting := True;
1135             Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1136          end if;
1137
1138          Result := pthread_mutex_unlock (S.L'Access);
1139          pragma Assert (Result = 0);
1140
1141          SSL.Abort_Undefer.all;
1142       end
1143       if;
1144    end Suspend_Until_True;
1145
1146    ----------------
1147    -- Check_Exit --
1148    ----------------
1149
1150    --  Dummy version
1151
1152    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1153       pragma Unreferenced (Self_ID);
1154    begin
1155       return True;
1156    end Check_Exit;
1157
1158    --------------------
1159    -- Check_No_Locks --
1160    --------------------
1161
1162    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1163       pragma Unreferenced (Self_ID);
1164    begin
1165       return True;
1166    end Check_No_Locks;
1167
1168    ----------------------
1169    -- Environment_Task --
1170    ----------------------
1171
1172    function Environment_Task return Task_Id is
1173    begin
1174       return Environment_Task_Id;
1175    end Environment_Task;
1176
1177    ------------------
1178    -- Suspend_Task --
1179    ------------------
1180
1181    function Suspend_Task
1182      (T           : ST.Task_Id;
1183       Thread_Self : Thread_Id) return Boolean
1184    is
1185    begin
1186       if T.Common.LL.Thread /= Thread_Self then
1187          return pthread_kill (T.Common.LL.Thread, SIGSTOP) = 0;
1188       else
1189          return True;
1190       end if;
1191    end Suspend_Task;
1192
1193    -----------------
1194    -- Resume_Task --
1195    -----------------
1196
1197    function Resume_Task
1198      (T           : ST.Task_Id;
1199       Thread_Self : Thread_Id) return Boolean
1200    is
1201    begin
1202       if T.Common.LL.Thread /= Thread_Self then
1203          return pthread_kill (T.Common.LL.Thread, SIGCONT) = 0;
1204       else
1205          return True;
1206       end if;
1207    end Resume_Task;
1208
1209    --------------------
1210    -- Stop_All_Tasks --
1211    --------------------
1212
1213    procedure Stop_All_Tasks is
1214    begin
1215       null;
1216    end Stop_All_Tasks;
1217
1218    ---------------
1219    -- Stop_Task --
1220    ---------------
1221
1222    function Stop_Task (T : ST.Task_Id) return Boolean is
1223       pragma Unreferenced (T);
1224    begin
1225       return False;
1226    end Stop_Task;
1227
1228    -------------------
1229    -- Continue_Task --
1230    -------------------
1231
1232    function Continue_Task (T : ST.Task_Id) return Boolean is
1233       pragma Unreferenced (T);
1234    begin
1235       return False;
1236    end Continue_Task;
1237
1238    ----------------
1239    -- Initialize --
1240    ----------------
1241
1242    procedure Initialize (Environment_Task : Task_Id) is
1243       act     : aliased struct_sigaction;
1244       old_act : aliased struct_sigaction;
1245       Tmp_Set : aliased sigset_t;
1246       Result  : Interfaces.C.int;
1247
1248       function State
1249         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1250       pragma Import (C, State, "__gnat_get_interrupt_state");
1251       --  Get interrupt state.  Defined in a-init.c
1252       --  The input argument is the interrupt number,
1253       --  and the result is one of the following:
1254
1255       Default : constant Character := 's';
1256       --    'n'   this interrupt not set by any Interrupt_State pragma
1257       --    'u'   Interrupt_State pragma set state to User
1258       --    'r'   Interrupt_State pragma set state to Runtime
1259       --    's'   Interrupt_State pragma set state to System (use "default"
1260       --           system handler)
1261
1262    begin
1263       Environment_Task_Id := Environment_Task;
1264
1265       Interrupt_Management.Initialize;
1266
1267       --  Prepare the set of signals that should be unblocked in all tasks
1268
1269       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1270       pragma Assert (Result = 0);
1271
1272       for J in Interrupt_Management.Interrupt_ID loop
1273          if System.Interrupt_Management.Keep_Unmasked (J) then
1274             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1275             pragma Assert (Result = 0);
1276          end if;
1277       end loop;
1278
1279       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1280       pragma Assert (Result = 0);
1281
1282       Result := pthread_condattr_init (Cond_Attr'Access);
1283       pragma Assert (Result = 0);
1284
1285       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1286
1287       --  Initialize the global RTS lock
1288
1289       Specific.Initialize (Environment_Task);
1290
1291       Enter_Task (Environment_Task);
1292
1293       --  Install the abort-signal handler
1294
1295       if State
1296           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1297       then
1298          act.sa_flags := 0;
1299          act.sa_handler := Abort_Handler'Address;
1300
1301          Result := sigemptyset (Tmp_Set'Access);
1302          pragma Assert (Result = 0);
1303          act.sa_mask := Tmp_Set;
1304
1305          Result :=
1306            sigaction
1307            (Signal (Interrupt_Management.Abort_Task_Interrupt),
1308             act'Unchecked_Access,
1309             old_act'Unchecked_Access);
1310          pragma Assert (Result = 0);
1311       end if;
1312    end Initialize;
1313
1314 end System.Task_Primitives.Operations;