gcc/ada/s-interr.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --                     S Y S T E M . I N T E R R U P T S                    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1992-2009, Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
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  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  Invariants:
  33
  34 --  All user-handleable interrupts are masked at all times in all
  35 --  tasks/threads except possibly for the Interrupt_Manager task.
  36
  37 --  When a user task wants to have the effect of masking/unmasking an
  38 --  interrupt, it must call Block_Interrupt/Unblock_Interrupt, which
  39 --  will have the effect of unmasking/masking the interrupt in the
  40 --  Interrupt_Manager task.
  41
  42 --  Note : Direct calls to sigaction, sigprocmask, pthread_sigsetmask or any
  43 --  other low-level interface that changes the interrupt action or
  44 --  interrupt mask needs a careful thought.
  45 --  One may achieve the effect of system calls first masking RTS blocked
  46 --  (by calling Block_Interrupt) for the interrupt under consideration.
  47 --  This will make all the tasks in RTS blocked for the Interrupt.
  48
  49 --  Once we associate a Server_Task with an interrupt, the task never
  50 --  goes away, and we never remove the association.
  51
  52 --  There is no more than one interrupt per Server_Task and no more than
  53 --  one Server_Task per interrupt.
  54
  55 with Ada.Task_Identification;
  56
  57 with System.Task_Primitives;
  58 with System.Interrupt_Management;
  59
  60 with System.Interrupt_Management.Operations;
  61 pragma Elaborate_All (System.Interrupt_Management.Operations);
  62
  63 with System.Task_Primitives.Operations;
  64 with System.Task_Primitives.Interrupt_Operations;
  65 with System.Storage_Elements;
  66 with System.Tasking.Utilities;
  67
  68 with System.Tasking.Rendezvous;
  69 pragma Elaborate_All (System.Tasking.Rendezvous);
  70
  71 with System.Tasking.Initialization;
  72 with System.Parameters;
  73
  74 with Ada.Unchecked_Conversion;
  75
  76 package body System.Interrupts is
  77
  78    use Parameters;
  79    use Tasking;
  80
  81    package POP renames System.Task_Primitives.Operations;
  82    package PIO renames System.Task_Primitives.Interrupt_Operations;
  83    package IMNG renames System.Interrupt_Management;
  84    package IMOP renames System.Interrupt_Management.Operations;
  85
  86    function To_System is new Ada.Unchecked_Conversion
  87      (Ada.Task_Identification.Task_Id, Task_Id);
  88
  89    -----------------
  90    -- Local Tasks --
  91    -----------------
  92
  93    --  WARNING: System.Tasking.Stages performs calls to this task with
  94    --  low-level constructs. Do not change this spec without synchronizing it.
  95
  96    task Interrupt_Manager is
  97       entry Detach_Interrupt_Entries (T : Task_Id);
  98
  99       entry Initialize (Mask : IMNG.Interrupt_Mask);
 100
 101       entry Attach_Handler
 102         (New_Handler : Parameterless_Handler;
 103          Interrupt   : Interrupt_ID;
 104          Static      : Boolean;
 105          Restoration : Boolean := False);
 106
 107       entry Exchange_Handler
 108         (Old_Handler : out Parameterless_Handler;
 109          New_Handler : Parameterless_Handler;
 110          Interrupt   : Interrupt_ID;
 111          Static      : Boolean);
 112
 113       entry Detach_Handler
 114         (Interrupt   : Interrupt_ID;
 115          Static      : Boolean);
 116
 117       entry Bind_Interrupt_To_Entry
 118         (T         : Task_Id;
 119          E         : Task_Entry_Index;
 120          Interrupt : Interrupt_ID);
 121
 122       entry Block_Interrupt (Interrupt : Interrupt_ID);
 123
 124       entry Unblock_Interrupt (Interrupt : Interrupt_ID);
 125
 126       entry Ignore_Interrupt (Interrupt : Interrupt_ID);
 127
 128       entry Unignore_Interrupt (Interrupt : Interrupt_ID);
 129
 130       pragma Interrupt_Priority (System.Interrupt_Priority'Last);
 131    end Interrupt_Manager;
 132
 133    task type Server_Task (Interrupt : Interrupt_ID) is
 134       pragma Priority (System.Interrupt_Priority'Last);
 135       --  Note: the above pragma Priority is strictly speaking improper since
 136       --  it is outside the range of allowed priorities, but the compiler
 137       --  treats system units specially and does not apply this range checking
 138       --  rule to system units.
 139
 140    end Server_Task;
 141
 142    type Server_Task_Access is access Server_Task;
 143
 144    -------------------------------
 145    -- Local Types and Variables --
 146    -------------------------------
 147
 148    type Entry_Assoc is record
 149       T : Task_Id;
 150       E : Task_Entry_Index;
 151    end record;
 152
 153    type Handler_Assoc is record
 154       H      : Parameterless_Handler;
 155       Static : Boolean;   --  Indicates static binding;
 156    end record;
 157
 158    User_Handler : array (Interrupt_ID'Range) of Handler_Assoc :=
 159                     (others => (null, Static => False));
 160    pragma Volatile_Components (User_Handler);
 161    --  Holds the protected procedure handler (if any) and its Static
 162    --  information for each interrupt. A handler is a Static one if it is
 163    --  specified through the pragma Attach_Handler. Attach_Handler. Otherwise,
 164    --  not static)
 165
 166    User_Entry : array (Interrupt_ID'Range) of Entry_Assoc :=
 167                   (others => (T => Null_Task, E => Null_Task_Entry));
 168    pragma Volatile_Components (User_Entry);
 169    --  Holds the task and entry index (if any) for each interrupt
 170
 171    Blocked : array (Interrupt_ID'Range) of Boolean := (others => False);
 172    pragma Atomic_Components (Blocked);
 173    --  True iff the corresponding interrupt is blocked in the process level
 174
 175    Ignored : array (Interrupt_ID'Range) of Boolean := (others => False);
 176    pragma Atomic_Components (Ignored);
 177    --  True iff the corresponding interrupt is blocked in the process level
 178
 179    Last_Unblocker :
 180      array (Interrupt_ID'Range) of Task_Id := (others => Null_Task);
 181    pragma Atomic_Components (Last_Unblocker);
 182    --  Holds the ID of the last Task which Unblocked this Interrupt. It
 183    --  contains Null_Task if no tasks have ever requested the Unblocking
 184    --  operation or the Interrupt is currently Blocked.
 185
 186    Server_ID : array (Interrupt_ID'Range) of Task_Id :=
 187                  (others => Null_Task);
 188    pragma Atomic_Components (Server_ID);
 189    --  Holds the Task_Id of the Server_Task for each interrupt. Task_Id is
 190    --  needed to accomplish locking per Interrupt base. Also is needed to
 191    --  decide whether to create a new Server_Task.
 192
 193    --  Type and Head, Tail of the list containing Registered Interrupt
 194    --  Handlers. These definitions are used to register the handlers
 195    --  specified by the pragma Interrupt_Handler.
 196
 197    type Registered_Handler;
 198    type R_Link is access all Registered_Handler;
 199
 200    type Registered_Handler is record
 201       H    : System.Address := System.Null_Address;
 202       Next : R_Link := null;
 203    end record;
 204
 205    Registered_Handler_Head : R_Link := null;
 206    Registered_Handler_Tail : R_Link := null;
 207
 208    Access_Hold : Server_Task_Access;
 209    --  Variable used to allocate Server_Task using "new"
 210
 211    -----------------------
 212    -- Local Subprograms --
 213    -----------------------
 214
 215    function Is_Registered (Handler : Parameterless_Handler) return Boolean;
 216    --  See if the Handler has been "pragma"ed using Interrupt_Handler. Always
 217    --  consider a null handler as registered.
 218
 219    --------------------
 220    -- Attach_Handler --
 221    --------------------
 222
 223    --  Calling this procedure with New_Handler = null and Static = True means
 224    --  we want to detach the current handler regardless of the previous
 225    --  handler's binding status (i.e. do not care if it is a dynamic or static
 226    --  handler).
 227
 228    --  This option is needed so that during the finalization of a PO, we can
 229    --  detach handlers attached through pragma Attach_Handler.
 230
 231    procedure Attach_Handler
 232      (New_Handler : Parameterless_Handler;
 233       Interrupt   : Interrupt_ID;
 234       Static      : Boolean := False)
 235    is
 236    begin
 237       if Is_Reserved (Interrupt) then
 238          raise Program_Error with
 239            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 240       end if;
 241
 242       Interrupt_Manager.Attach_Handler (New_Handler, Interrupt, Static);
 243
 244    end Attach_Handler;
 245
 246    -----------------------------
 247    -- Bind_Interrupt_To_Entry --
 248    -----------------------------
 249
 250    --  This procedure raises a Program_Error if it tries to bind an interrupt
 251    --  to which an Entry or a Procedure is already bound.
 252
 253    procedure Bind_Interrupt_To_Entry
 254      (T       : Task_Id;
 255       E       : Task_Entry_Index;
 256       Int_Ref : System.Address)
 257    is
 258       Interrupt   : constant Interrupt_ID :=
 259                       Interrupt_ID (Storage_Elements.To_Integer (Int_Ref));
 260
 261    begin
 262       if Is_Reserved (Interrupt) then
 263          raise Program_Error with
 264            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 265       end if;
 266
 267       Interrupt_Manager.Bind_Interrupt_To_Entry (T, E, Interrupt);
 268    end Bind_Interrupt_To_Entry;
 269
 270    ---------------------
 271    -- Block_Interrupt --
 272    ---------------------
 273
 274    procedure Block_Interrupt (Interrupt : Interrupt_ID) is
 275    begin
 276       if Is_Reserved (Interrupt) then
 277          raise Program_Error with
 278            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 279       end if;
 280
 281       Interrupt_Manager.Block_Interrupt (Interrupt);
 282    end Block_Interrupt;
 283
 284    ---------------------
 285    -- Current_Handler --
 286    ---------------------
 287
 288    function Current_Handler
 289      (Interrupt : Interrupt_ID) return Parameterless_Handler
 290    is
 291    begin
 292       if Is_Reserved (Interrupt) then
 293          raise Program_Error with
 294            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 295       end if;
 296
 297       --  ??? Since Parameterless_Handler is not Atomic, the current
 298       --  implementation is wrong. We need a new service in Interrupt_Manager
 299       --  to ensure atomicity.
 300
 301       return User_Handler (Interrupt).H;
 302    end Current_Handler;
 303
 304    --------------------
 305    -- Detach_Handler --
 306    --------------------
 307
 308    --  Calling this procedure with Static = True means we want to Detach the
 309    --  current handler regardless of the previous handler's binding status
 310    --  (i.e. do not care if it is a dynamic or static handler).
 311
 312    --  This option is needed so that during the finalization of a PO, we can
 313    --  detach handlers attached through pragma Attach_Handler.
 314
 315    procedure Detach_Handler
 316      (Interrupt : Interrupt_ID;
 317       Static    : Boolean := False)
 318    is
 319    begin
 320       if Is_Reserved (Interrupt) then
 321          raise Program_Error with
 322            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 323       end if;
 324
 325       Interrupt_Manager.Detach_Handler (Interrupt, Static);
 326    end Detach_Handler;
 327
 328    ------------------------------
 329    -- Detach_Interrupt_Entries --
 330    ------------------------------
 331
 332    procedure Detach_Interrupt_Entries (T : Task_Id) is
 333    begin
 334       Interrupt_Manager.Detach_Interrupt_Entries (T);
 335    end Detach_Interrupt_Entries;
 336
 337    ----------------------
 338    -- Exchange_Handler --
 339    ----------------------
 340
 341    --  Calling this procedure with New_Handler = null and Static = True means
 342    --  we want to detach the current handler regardless of the previous
 343    --  handler's binding status (i.e. do not care if it is a dynamic or static
 344    --  handler).
 345
 346    --  This option is needed so that during the finalization of a PO, we can
 347    --  detach handlers attached through pragma Attach_Handler.
 348
 349    procedure Exchange_Handler
 350      (Old_Handler : out Parameterless_Handler;
 351       New_Handler : Parameterless_Handler;
 352       Interrupt   : Interrupt_ID;
 353       Static      : Boolean := False)
 354    is
 355    begin
 356       if Is_Reserved (Interrupt) then
 357          raise Program_Error with
 358            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 359       end if;
 360
 361       Interrupt_Manager.Exchange_Handler
 362         (Old_Handler, New_Handler, Interrupt, Static);
 363    end Exchange_Handler;
 364
 365    --------------
 366    -- Finalize --
 367    --------------
 368
 369    procedure Finalize (Object : in out Static_Interrupt_Protection) is
 370       function State
 371         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
 372       pragma Import (C, State, "__gnat_get_interrupt_state");
 373       --  Get interrupt state for interrupt number Int. Defined in init.c
 374
 375       Default : constant Character := 's';
 376       --    's'   Interrupt_State pragma set state to System (use "default"
 377       --           system handler)
 378
 379    begin
 380       --  ??? loop to be executed only when we're not doing library level
 381       --  finalization, since in this case all interrupt tasks are gone.
 382
 383       --  If the Abort_Task signal is set to system, it means that we cannot
 384       --  reset interrupt handlers since this would require sending the abort
 385       --  signal to the Server_Task
 386
 387       if not Interrupt_Manager'Terminated
 388         and then State (System.Interrupt_Management.Abort_Task_Interrupt)
 389                   /= Default
 390       then
 391          for N in reverse Object.Previous_Handlers'Range loop
 392             Interrupt_Manager.Attach_Handler
 393               (New_Handler => Object.Previous_Handlers (N).Handler,
 394                Interrupt   => Object.Previous_Handlers (N).Interrupt,
 395                Static      => Object.Previous_Handlers (N).Static,
 396                Restoration => True);
 397          end loop;
 398       end if;
 399
 400       Tasking.Protected_Objects.Entries.Finalize
 401         (Tasking.Protected_Objects.Entries.Protection_Entries (Object));
 402    end Finalize;
 403
 404    -------------------------------------
 405    -- Has_Interrupt_Or_Attach_Handler --
 406    -------------------------------------
 407
 408    --  Need comments as to why these always return True ???
 409
 410    function Has_Interrupt_Or_Attach_Handler
 411      (Object : access Dynamic_Interrupt_Protection) return Boolean
 412    is
 413       pragma Unreferenced (Object);
 414    begin
 415       return True;
 416    end Has_Interrupt_Or_Attach_Handler;
 417
 418    function Has_Interrupt_Or_Attach_Handler
 419      (Object : access Static_Interrupt_Protection) return Boolean
 420    is
 421       pragma Unreferenced (Object);
 422    begin
 423       return True;
 424    end Has_Interrupt_Or_Attach_Handler;
 425
 426    ----------------------
 427    -- Ignore_Interrupt --
 428    ----------------------
 429
 430    procedure Ignore_Interrupt (Interrupt : Interrupt_ID) is
 431    begin
 432       if Is_Reserved (Interrupt) then
 433          raise Program_Error with
 434            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 435       end if;
 436
 437       Interrupt_Manager.Ignore_Interrupt (Interrupt);
 438    end Ignore_Interrupt;
 439
 440    ----------------------
 441    -- Install_Handlers --
 442    ----------------------
 443
 444    procedure Install_Handlers
 445      (Object       : access Static_Interrupt_Protection;
 446       New_Handlers : New_Handler_Array)
 447    is
 448    begin
 449       for N in New_Handlers'Range loop
 450
 451          --  We need a lock around this ???
 452
 453          Object.Previous_Handlers (N).Interrupt := New_Handlers (N).Interrupt;
 454          Object.Previous_Handlers (N).Static    := User_Handler
 455            (New_Handlers (N).Interrupt).Static;
 456
 457          --  We call Exchange_Handler and not directly Interrupt_Manager.
 458          --  Exchange_Handler so we get the Is_Reserved check.
 459
 460          Exchange_Handler
 461            (Old_Handler => Object.Previous_Handlers (N).Handler,
 462             New_Handler => New_Handlers (N).Handler,
 463             Interrupt   => New_Handlers (N).Interrupt,
 464             Static      => True);
 465       end loop;
 466    end Install_Handlers;
 467
 468    ---------------------------------
 469    -- Install_Restricted_Handlers --
 470    ---------------------------------
 471
 472    procedure Install_Restricted_Handlers (Handlers : New_Handler_Array) is
 473    begin
 474       for N in Handlers'Range loop
 475          Attach_Handler (Handlers (N).Handler, Handlers (N).Interrupt, True);
 476       end loop;
 477    end Install_Restricted_Handlers;
 478
 479    ----------------
 480    -- Is_Blocked --
 481    ----------------
 482
 483    function Is_Blocked (Interrupt : Interrupt_ID) return Boolean is
 484    begin
 485       if Is_Reserved (Interrupt) then
 486          raise Program_Error with
 487            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 488       end if;
 489
 490       return Blocked (Interrupt);
 491    end Is_Blocked;
 492
 493    -----------------------
 494    -- Is_Entry_Attached --
 495    -----------------------
 496
 497    function Is_Entry_Attached (Interrupt : Interrupt_ID) return Boolean is
 498    begin
 499       if Is_Reserved (Interrupt) then
 500          raise Program_Error with
 501            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 502       end if;
 503
 504       return User_Entry (Interrupt).T /= Null_Task;
 505    end Is_Entry_Attached;
 506
 507    -------------------------
 508    -- Is_Handler_Attached --
 509    -------------------------
 510
 511    function Is_Handler_Attached (Interrupt : Interrupt_ID) return Boolean is
 512    begin
 513       if Is_Reserved (Interrupt) then
 514          raise Program_Error with
 515            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 516       end if;
 517
 518       return User_Handler (Interrupt).H /= null;
 519    end Is_Handler_Attached;
 520
 521    ----------------
 522    -- Is_Ignored --
 523    ----------------
 524
 525    function Is_Ignored (Interrupt : Interrupt_ID) return Boolean is
 526    begin
 527       if Is_Reserved (Interrupt) then
 528          raise Program_Error with
 529            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 530       end if;
 531
 532       return Ignored (Interrupt);
 533    end Is_Ignored;
 534
 535    -------------------
 536    -- Is_Registered --
 537    -------------------
 538
 539    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
 540
 541       type Fat_Ptr is record
 542          Object_Addr  : System.Address;
 543          Handler_Addr : System.Address;
 544       end record;
 545
 546       function To_Fat_Ptr is new Ada.Unchecked_Conversion
 547         (Parameterless_Handler, Fat_Ptr);
 548
 549       Ptr : R_Link;
 550       Fat : Fat_Ptr;
 551
 552    begin
 553       if Handler = null then
 554          return True;
 555       end if;
 556
 557       Fat := To_Fat_Ptr (Handler);
 558
 559       Ptr := Registered_Handler_Head;
 560
 561       while Ptr /= null loop
 562          if Ptr.H = Fat.Handler_Addr then
 563             return True;
 564          end if;
 565
 566          Ptr := Ptr.Next;
 567       end loop;
 568
 569       return False;
 570    end Is_Registered;
 571
 572    -----------------
 573    -- Is_Reserved --
 574    -----------------
 575
 576    function Is_Reserved (Interrupt : Interrupt_ID) return Boolean is
 577    begin
 578       return IMNG.Reserve (IMNG.Interrupt_ID (Interrupt));
 579    end Is_Reserved;
 580
 581    ---------------
 582    -- Reference --
 583    ---------------
 584
 585    function Reference (Interrupt : Interrupt_ID) return System.Address is
 586    begin
 587       if Is_Reserved (Interrupt) then
 588          raise Program_Error with
 589            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 590       end if;
 591
 592       return Storage_Elements.To_Address
 593         (Storage_Elements.Integer_Address (Interrupt));
 594    end Reference;
 595
 596    ---------------------------------
 597    -- Register_Interrupt_Handler  --
 598    ---------------------------------
 599
 600    procedure Register_Interrupt_Handler (Handler_Addr : System.Address) is
 601       New_Node_Ptr : R_Link;
 602
 603    begin
 604       --  This routine registers the Handler as usable for Dynamic Interrupt
 605       --  Handler. Routines attaching and detaching Handler dynamically should
 606       --  first consult if the Handler is registered. A Program Error should
 607       --  be raised if it is not registered.
 608
 609       --  The pragma Interrupt_Handler can only appear in the library level PO
 610       --  definition and instantiation. Therefore, we do not need to implement
 611       --  Unregistering operation. Neither we need to protect the queue
 612       --  structure using a Lock.
 613
 614       pragma Assert (Handler_Addr /= System.Null_Address);
 615
 616       New_Node_Ptr := new Registered_Handler;
 617       New_Node_Ptr.H := Handler_Addr;
 618
 619       if Registered_Handler_Head = null then
 620          Registered_Handler_Head := New_Node_Ptr;
 621          Registered_Handler_Tail := New_Node_Ptr;
 622
 623       else
 624          Registered_Handler_Tail.Next := New_Node_Ptr;
 625          Registered_Handler_Tail := New_Node_Ptr;
 626       end if;
 627    end Register_Interrupt_Handler;
 628
 629    -----------------------
 630    -- Unblock_Interrupt --
 631    -----------------------
 632
 633    procedure Unblock_Interrupt (Interrupt : Interrupt_ID) is
 634    begin
 635       if Is_Reserved (Interrupt) then
 636          raise Program_Error with
 637            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 638       end if;
 639
 640       Interrupt_Manager.Unblock_Interrupt (Interrupt);
 641    end Unblock_Interrupt;
 642
 643    ------------------
 644    -- Unblocked_By --
 645    ------------------
 646
 647    function Unblocked_By
 648      (Interrupt : Interrupt_ID) return System.Tasking.Task_Id
 649    is
 650    begin
 651       if Is_Reserved (Interrupt) then
 652          raise Program_Error with
 653            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 654       end if;
 655
 656       return Last_Unblocker (Interrupt);
 657    end Unblocked_By;
 658
 659    ------------------------
 660    -- Unignore_Interrupt --
 661    ------------------------
 662
 663    procedure Unignore_Interrupt (Interrupt : Interrupt_ID) is
 664    begin
 665       if Is_Reserved (Interrupt) then
 666          raise Program_Error with
 667            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 668       end if;
 669
 670       Interrupt_Manager.Unignore_Interrupt (Interrupt);
 671    end Unignore_Interrupt;
 672
 673    -----------------------
 674    -- Interrupt_Manager --
 675    -----------------------
 676
 677    task body Interrupt_Manager is
 678
 679       ---------------------
 680       -- Local Variables --
 681       ---------------------
 682
 683       Intwait_Mask  : aliased IMNG.Interrupt_Mask;
 684       Ret_Interrupt : Interrupt_ID;
 685       Old_Mask      : aliased IMNG.Interrupt_Mask;
 686       Old_Handler   : Parameterless_Handler;
 687
 688       --------------------
 689       -- Local Routines --
 690       --------------------
 691
 692       procedure Bind_Handler (Interrupt : Interrupt_ID);
 693       --  This procedure does not do anything if the Interrupt is blocked.
 694       --  Otherwise, we have to interrupt Server_Task for status change through
 695       --  Wakeup interrupt.
 696
 697       procedure Unbind_Handler (Interrupt : Interrupt_ID);
 698       --  This procedure does not do anything if the Interrupt is blocked.
 699       --  Otherwise, we have to interrupt Server_Task for status change
 700       --  through abort interrupt.
 701
 702       procedure Unprotected_Exchange_Handler
 703         (Old_Handler : out Parameterless_Handler;
 704          New_Handler : Parameterless_Handler;
 705          Interrupt   : Interrupt_ID;
 706          Static      : Boolean;
 707          Restoration : Boolean := False);
 708
 709       procedure Unprotected_Detach_Handler
 710         (Interrupt   : Interrupt_ID;
 711          Static      : Boolean);
 712
 713       ------------------
 714       -- Bind_Handler --
 715       ------------------
 716
 717       procedure Bind_Handler (Interrupt : Interrupt_ID) is
 718       begin
 719          if not Blocked (Interrupt) then
 720
 721             --  Mask this task for the given Interrupt so that all tasks
 722             --  are masked for the Interrupt and the actual delivery of the
 723             --  Interrupt will be caught using "sigwait" by the
 724             --  corresponding Server_Task.
 725
 726             IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt));
 727
 728             --  We have installed a Handler or an Entry before we called
 729             --  this procedure. If the Handler Task is waiting to be awakened,
 730             --  do it here. Otherwise, the interrupt will be discarded.
 731
 732             POP.Wakeup (Server_ID (Interrupt), Interrupt_Server_Idle_Sleep);
 733          end if;
 734       end Bind_Handler;
 735
 736       --------------------
 737       -- Unbind_Handler --
 738       --------------------
 739
 740       procedure Unbind_Handler (Interrupt : Interrupt_ID) is
 741          Server : System.Tasking.Task_Id;
 742       begin
 743          if not Blocked (Interrupt) then
 744             --  Currently, there is a Handler or an Entry attached and
 745             --  corresponding Server_Task is waiting on "sigwait."
 746             --  We have to wake up the Server_Task and make it
 747             --  wait on condition variable by sending an
 748             --  Abort_Task_Interrupt
 749
 750             Server := Server_ID (Interrupt);
 751
 752             case Server.Common.State is
 753                when Interrupt_Server_Idle_Sleep |
 754                     Interrupt_Server_Blocked_Interrupt_Sleep
 755                =>
 756                   POP.Wakeup (Server, Server.Common.State);
 757
 758                when Interrupt_Server_Blocked_On_Event_Flag =>
 759                   POP.Abort_Task (Server);
 760
 761                   --  Make sure corresponding Server_Task is out of its
 762                   --  own sigwait state.
 763
 764                   Ret_Interrupt :=
 765                     Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access));
 766                   pragma Assert
 767                     (Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt));
 768
 769                when Runnable =>
 770                   null;
 771
 772                when others =>
 773                   pragma Assert (False);
 774                   null;
 775             end case;
 776
 777             IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
 778
 779             --  Unmake the Interrupt for this task in order to allow default
 780             --  action again.
 781
 782             IMOP.Thread_Unblock_Interrupt (IMNG.Interrupt_ID (Interrupt));
 783
 784          else
 785             IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
 786          end if;
 787       end Unbind_Handler;
 788
 789       --------------------------------
 790       -- Unprotected_Detach_Handler --
 791       --------------------------------
 792
 793       procedure Unprotected_Detach_Handler
 794         (Interrupt   : Interrupt_ID;
 795          Static      : Boolean)
 796       is
 797          Old_Handler : Parameterless_Handler;
 798
 799       begin
 800          if User_Entry (Interrupt).T /= Null_Task then
 801
 802             --  In case we have an Interrupt Entry installed.
 803             --  raise a program error. (propagate it to the caller).
 804
 805             raise Program_Error with
 806               "An interrupt entry is already installed";
 807          end if;
 808
 809          --  Note : Static = True will pass the following check. That is the
 810          --  case when we want to detach a handler regardless of the static
 811          --  status of the current_Handler.
 812
 813          if not Static and then User_Handler (Interrupt).Static then
 814
 815             --  Tries to detach a static Interrupt Handler.
 816             --  raise a program error.
 817
 818             raise Program_Error with
 819               "Trying to detach a static Interrupt Handler";
 820          end if;
 821
 822          --  The interrupt should no longer be ignored if
 823          --  it was ever ignored.
 824
 825          Ignored (Interrupt) := False;
 826
 827          Old_Handler := User_Handler (Interrupt).H;
 828
 829          --  The new handler
 830
 831          User_Handler (Interrupt).H := null;
 832          User_Handler (Interrupt).Static := False;
 833
 834          if Old_Handler /= null then
 835             Unbind_Handler (Interrupt);
 836          end if;
 837       end Unprotected_Detach_Handler;
 838
 839       ----------------------------------
 840       -- Unprotected_Exchange_Handler --
 841       ----------------------------------
 842
 843       procedure Unprotected_Exchange_Handler
 844         (Old_Handler : out Parameterless_Handler;
 845          New_Handler : Parameterless_Handler;
 846          Interrupt   : Interrupt_ID;
 847          Static      : Boolean;
 848          Restoration : Boolean := False)
 849       is
 850       begin
 851          if User_Entry (Interrupt).T /= Null_Task then
 852
 853             --  In case we have an Interrupt Entry already installed.
 854             --  raise a program error. (propagate it to the caller).
 855
 856             raise Program_Error with
 857               "An interrupt is already installed";
 858          end if;
 859
 860          --  Note : A null handler with Static = True will pass the
 861          --  following check. That is the case when we want to Detach a
 862          --  handler regardless of the Static status of the current_Handler.
 863
 864          --  We don't check anything if Restoration is True, since we
 865          --  may be detaching a static handler to restore a dynamic one.
 866
 867          if not Restoration and then not Static
 868
 869             --  Tries to overwrite a static Interrupt Handler with a
 870             --  dynamic Handler
 871
 872            and then (User_Handler (Interrupt).Static
 873
 874                         --  The new handler is not specified as an
 875                         --  Interrupt Handler by a pragma.
 876
 877                         or else not Is_Registered (New_Handler))
 878          then
 879             raise Program_Error with
 880               "Trying to overwrite a static Interrupt Handler with a " &
 881               "dynamic Handler";
 882          end if;
 883
 884          --  The interrupt should no longer be ignored if
 885          --  it was ever ignored.
 886
 887          Ignored (Interrupt) := False;
 888
 889          --  Save the old handler
 890
 891          Old_Handler := User_Handler (Interrupt).H;
 892
 893          --  The new handler
 894
 895          User_Handler (Interrupt).H := New_Handler;
 896
 897          if New_Handler = null then
 898
 899             --  The null handler means we are detaching the handler
 900
 901             User_Handler (Interrupt).Static := False;
 902
 903          else
 904             User_Handler (Interrupt).Static := Static;
 905          end if;
 906
 907          --  Invoke a corresponding Server_Task if not yet created.
 908          --  Place Task_Id info in Server_ID array.
 909
 910          if Server_ID (Interrupt) = Null_Task then
 911
 912             --  When a new Server_Task is created, it should have its
 913             --  signal mask set to the All_Tasks_Mask.
 914
 915             IMOP.Set_Interrupt_Mask
 916               (IMOP.All_Tasks_Mask'Access, Old_Mask'Access);
 917             Access_Hold := new Server_Task (Interrupt);
 918             IMOP.Set_Interrupt_Mask (Old_Mask'Access);
 919
 920             Server_ID (Interrupt) := To_System (Access_Hold.all'Identity);
 921          end if;
 922
 923          if New_Handler = null then
 924             if Old_Handler /= null then
 925                Unbind_Handler (Interrupt);
 926             end if;
 927
 928             return;
 929          end if;
 930
 931          if Old_Handler = null then
 932             Bind_Handler (Interrupt);
 933          end if;
 934       end Unprotected_Exchange_Handler;
 935
 936    --  Start of processing for Interrupt_Manager
 937
 938    begin
 939       --  By making this task independent of master, when the process
 940       --  goes away, the Interrupt_Manager will terminate gracefully.
 941
 942       System.Tasking.Utilities.Make_Independent;
 943
 944       --  Environment task gets its own interrupt mask, saves it,
 945       --  and then masks all interrupts except the Keep_Unmasked set.
 946
 947       --  During rendezvous, the Interrupt_Manager receives the old
 948       --  interrupt mask of the environment task, and sets its own
 949       --  interrupt mask to that value.
 950
 951       --  The environment task will call the entry of Interrupt_Manager some
 952       --  during elaboration of the body of this package.
 953
 954       accept Initialize (Mask : IMNG.Interrupt_Mask) do
 955          declare
 956             The_Mask : aliased IMNG.Interrupt_Mask;
 957
 958          begin
 959             IMOP.Copy_Interrupt_Mask (The_Mask, Mask);
 960             IMOP.Set_Interrupt_Mask (The_Mask'Access);
 961          end;
 962       end Initialize;
 963
 964       --  Note: All tasks in RTS will have all the Reserve Interrupts
 965       --  being masked (except the Interrupt_Manager) and Keep_Unmasked
 966       --  unmasked when created.
 967
 968       --  Abort_Task_Interrupt is one of the Interrupt unmasked
 969       --  in all tasks. We mask the Interrupt in this particular task
 970       --  so that "sigwait" is possible to catch an explicitly sent
 971       --  Abort_Task_Interrupt from the Server_Tasks.
 972
 973       --  This sigwaiting is needed so that we make sure a Server_Task is
 974       --  out of its own sigwait state. This extra synchronization is
 975       --  necessary to prevent following scenarios.
 976
 977       --   1) Interrupt_Manager sends an Abort_Task_Interrupt to the
 978       --      Server_Task then changes its own interrupt mask (OS level).
 979       --      If an interrupt (corresponding to the Server_Task) arrives
 980       --      in the mean time we have the Interrupt_Manager unmasked and
 981       --      the Server_Task waiting on sigwait.
 982
 983       --   2) For unbinding handler, we install a default action in the
 984       --      Interrupt_Manager. POSIX.1c states that the result of using
 985       --      "sigwait" and "sigaction" simultaneously on the same interrupt
 986       --      is undefined. Therefore, we need to be informed from the
 987       --      Server_Task of the fact that the Server_Task is out of its
 988       --      sigwait stage.
 989
 990       IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access);
 991       IMOP.Add_To_Interrupt_Mask
 992         (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt);
 993       IMOP.Thread_Block_Interrupt
 994         (IMNG.Abort_Task_Interrupt);
 995
 996       loop
 997          --  A block is needed to absorb Program_Error exception
 998
 999          begin
1000             select
1001                accept Attach_Handler
1002                   (New_Handler : Parameterless_Handler;
1003                    Interrupt   : Interrupt_ID;
1004                    Static      : Boolean;
1005                    Restoration : Boolean := False)
1006                do
1007                   Unprotected_Exchange_Handler
1008                     (Old_Handler, New_Handler, Interrupt, Static, Restoration);
1009                end Attach_Handler;
1010
1011             or
1012                accept Exchange_Handler
1013                   (Old_Handler : out Parameterless_Handler;
1014                    New_Handler : Parameterless_Handler;
1015                    Interrupt   : Interrupt_ID;
1016                    Static      : Boolean)
1017                do
1018                   Unprotected_Exchange_Handler
1019                     (Old_Handler, New_Handler, Interrupt, Static);
1020                end Exchange_Handler;
1021
1022             or
1023                accept Detach_Handler
1024                  (Interrupt   : Interrupt_ID;
1025                   Static      : Boolean)
1026                do
1027                   Unprotected_Detach_Handler (Interrupt, Static);
1028                end Detach_Handler;
1029
1030             or
1031                accept Bind_Interrupt_To_Entry
1032                  (T       : Task_Id;
1033                   E       : Task_Entry_Index;
1034                   Interrupt : Interrupt_ID)
1035                do
1036                   --  if there is a binding already (either a procedure or an
1037                   --  entry), raise Program_Error (propagate it to the caller).
1038
1039                   if User_Handler (Interrupt).H /= null
1040                     or else User_Entry (Interrupt).T /= Null_Task
1041                   then
1042                      raise Program_Error with
1043                        "A binding for this interrupt is already present";
1044                   end if;
1045
1046                   --  The interrupt should no longer be ignored if
1047                   --  it was ever ignored.
1048
1049                   Ignored (Interrupt) := False;
1050                   User_Entry (Interrupt) := Entry_Assoc'(T => T, E => E);
1051
1052                   --  Indicate the attachment of Interrupt Entry in ATCB.
1053                   --  This is need so that when an Interrupt Entry task
1054                   --  terminates the binding can be cleaned. The call to
1055                   --  unbinding must be made by the task before it terminates.
1056
1057                   T.Interrupt_Entry := True;
1058
1059                   --  Invoke a corresponding Server_Task if not yet created.
1060                   --  Place Task_Id info in Server_ID array.
1061
1062                   if Server_ID (Interrupt) = Null_Task then
1063
1064                      --  When a new Server_Task is created, it should have its
1065                      --  signal mask set to the All_Tasks_Mask.
1066
1067                      IMOP.Set_Interrupt_Mask
1068                        (IMOP.All_Tasks_Mask'Access, Old_Mask'Access);
1069                      Access_Hold := new Server_Task (Interrupt);
1070                      IMOP.Set_Interrupt_Mask (Old_Mask'Access);
1071                      Server_ID (Interrupt) :=
1072                        To_System (Access_Hold.all'Identity);
1073                   end if;
1074
1075                   Bind_Handler (Interrupt);
1076                end Bind_Interrupt_To_Entry;
1077
1078             or
1079                accept Detach_Interrupt_Entries (T : Task_Id) do
1080                   for J in Interrupt_ID'Range loop
1081                      if not Is_Reserved (J) then
1082                         if User_Entry (J).T = T then
1083
1084                            --  The interrupt should no longer be ignored if
1085                            --  it was ever ignored.
1086
1087                            Ignored (J) := False;
1088                            User_Entry (J) := Entry_Assoc'
1089                              (T => Null_Task, E => Null_Task_Entry);
1090                            Unbind_Handler (J);
1091                         end if;
1092                      end if;
1093                   end loop;
1094
1095                   --  Indicate in ATCB that no Interrupt Entries are attached
1096
1097                   T.Interrupt_Entry := False;
1098                end Detach_Interrupt_Entries;
1099
1100             or
1101                accept Block_Interrupt (Interrupt : Interrupt_ID) do
1102                   if Blocked (Interrupt) then
1103                      return;
1104                   end if;
1105
1106                   Blocked (Interrupt) := True;
1107                   Last_Unblocker (Interrupt) := Null_Task;
1108
1109                   --  Mask this task for the given Interrupt so that all tasks
1110                   --  are masked for the Interrupt.
1111
1112                   IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt));
1113
1114                   if User_Handler (Interrupt).H /= null
1115                     or else User_Entry (Interrupt).T /= Null_Task
1116                   then
1117                      --  This is the case where the Server_Task is waiting
1118                      --  on "sigwait." Wake it up by sending an
1119                      --  Abort_Task_Interrupt so that the Server_Task
1120                      --  waits on Cond.
1121
1122                      POP.Abort_Task (Server_ID (Interrupt));
1123
1124                      --  Make sure corresponding Server_Task is out of its own
1125                      --  sigwait state.
1126
1127                      Ret_Interrupt := Interrupt_ID
1128                        (IMOP.Interrupt_Wait (Intwait_Mask'Access));
1129                      pragma Assert
1130                        (Ret_Interrupt =
1131                         Interrupt_ID (IMNG.Abort_Task_Interrupt));
1132                   end if;
1133                end Block_Interrupt;
1134
1135             or
1136                accept Unblock_Interrupt (Interrupt : Interrupt_ID) do
1137                   if not Blocked (Interrupt) then
1138                      return;
1139                   end if;
1140
1141                   Blocked (Interrupt) := False;
1142                   Last_Unblocker (Interrupt) :=
1143                     To_System (Unblock_Interrupt'Caller);
1144
1145                   if User_Handler (Interrupt).H = null
1146                     and then User_Entry (Interrupt).T = Null_Task
1147                   then
1148                      --  No handler is attached. Unmask the Interrupt so that
1149                      --  the default action can be carried out.
1150
1151                      IMOP.Thread_Unblock_Interrupt
1152                        (IMNG.Interrupt_ID (Interrupt));
1153
1154                   else
1155                      --  The Server_Task must be waiting on the Cond variable
1156                      --  since it was being blocked and an Interrupt Hander or
1157                      --  an Entry was there. Wake it up and let it change
1158                      --  it place of waiting according to its new state.
1159
1160                      POP.Wakeup (Server_ID (Interrupt),
1161                        Interrupt_Server_Blocked_Interrupt_Sleep);
1162                   end if;
1163                end Unblock_Interrupt;
1164
1165             or
1166                accept Ignore_Interrupt (Interrupt : Interrupt_ID) do
1167                   if Ignored (Interrupt) then
1168                      return;
1169                   end if;
1170
1171                   Ignored (Interrupt) := True;
1172
1173                   --  If there is a handler associated with the Interrupt,
1174                   --  detach it first. In this way we make sure that the
1175                   --  Server_Task is not on sigwait. This is legal since
1176                   --  Unignore_Interrupt is to install the default action.
1177
1178                   if User_Handler (Interrupt).H /= null then
1179                      Unprotected_Detach_Handler
1180                        (Interrupt => Interrupt, Static => True);
1181
1182                   elsif User_Entry (Interrupt).T /= Null_Task then
1183                      User_Entry (Interrupt) := Entry_Assoc'
1184                        (T => Null_Task, E => Null_Task_Entry);
1185                      Unbind_Handler (Interrupt);
1186                   end if;
1187
1188                   IMOP.Install_Ignore_Action (IMNG.Interrupt_ID (Interrupt));
1189                end Ignore_Interrupt;
1190
1191             or
1192                accept Unignore_Interrupt (Interrupt : Interrupt_ID) do
1193                   Ignored (Interrupt) := False;
1194
1195                   --  If there is a handler associated with the Interrupt,
1196                   --  detach it first. In this way we make sure that the
1197                   --  Server_Task is not on sigwait. This is legal since
1198                   --  Unignore_Interrupt is to install the default action.
1199
1200                   if User_Handler (Interrupt).H /= null then
1201                      Unprotected_Detach_Handler
1202                        (Interrupt => Interrupt, Static => True);
1203
1204                   elsif User_Entry (Interrupt).T /= Null_Task then
1205                      User_Entry (Interrupt) := Entry_Assoc'
1206                        (T => Null_Task, E => Null_Task_Entry);
1207                      Unbind_Handler (Interrupt);
1208                   end if;
1209
1210                   IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
1211                end Unignore_Interrupt;
1212             end select;
1213
1214          exception
1215             --  If there is a program error we just want to propagate it to
1216             --  the caller and do not want to stop this task.
1217
1218             when Program_Error =>
1219                null;
1220
1221             when others =>
1222                pragma Assert (False);
1223                null;
1224          end;
1225       end loop;
1226    end Interrupt_Manager;
1227
1228    -----------------
1229    -- Server_Task --
1230    -----------------
1231
1232    task body Server_Task is
1233       Intwait_Mask    : aliased IMNG.Interrupt_Mask;
1234       Ret_Interrupt   : Interrupt_ID;
1235       Self_ID         : constant Task_Id := Self;
1236       Tmp_Handler     : Parameterless_Handler;
1237       Tmp_ID          : Task_Id;
1238       Tmp_Entry_Index : Task_Entry_Index;
1239
1240    begin
1241       --  By making this task independent of master, when the process
1242       --  goes away, the Server_Task will terminate gracefully.
1243
1244       System.Tasking.Utilities.Make_Independent;
1245
1246       --  Install default action in system level
1247
1248       IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
1249
1250       --  Note: All tasks in RTS will have all the Reserve Interrupts being
1251       --  masked (except the Interrupt_Manager) and Keep_Unmasked unmasked when
1252       --  created.
1253
1254       --  Abort_Task_Interrupt is one of the Interrupt unmasked in all tasks.
1255       --  We mask the Interrupt in this particular task so that "sigwait" is
1256       --  possible to catch an explicitly sent Abort_Task_Interrupt from the
1257       --  Interrupt_Manager.
1258
1259       --  There are two Interrupt interrupts that this task catch through
1260       --  "sigwait." One is the Interrupt this task is designated to catch
1261       --  in order to execute user handler or entry. The other one is the
1262       --  Abort_Task_Interrupt. This interrupt is being sent from the
1263       --  Interrupt_Manager to inform status changes (e.g: become Blocked,
1264       --  Handler or Entry is to be detached).
1265
1266       --  Prepare a mask to used for sigwait
1267
1268       IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access);
1269
1270       IMOP.Add_To_Interrupt_Mask
1271         (Intwait_Mask'Access, IMNG.Interrupt_ID (Interrupt));
1272
1273       IMOP.Add_To_Interrupt_Mask
1274         (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt);
1275
1276       IMOP.Thread_Block_Interrupt
1277         (IMNG.Abort_Task_Interrupt);
1278
1279       PIO.Set_Interrupt_ID (IMNG.Interrupt_ID (Interrupt), Self_ID);
1280
1281       loop
1282          System.Tasking.Initialization.Defer_Abort (Self_ID);
1283
1284          if Single_Lock then
1285             POP.Lock_RTS;
1286          end if;
1287
1288          POP.Write_Lock (Self_ID);
1289
1290          if User_Handler (Interrupt).H = null
1291            and then User_Entry (Interrupt).T = Null_Task
1292          then
1293             --  No Interrupt binding. If there is an interrupt,
1294             --  Interrupt_Manager will take default action.
1295
1296             Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep;
1297             POP.Sleep (Self_ID, Interrupt_Server_Idle_Sleep);
1298             Self_ID.Common.State := Runnable;
1299
1300          elsif Blocked (Interrupt) then
1301
1302             --  Interrupt is blocked. Stay here, so we won't catch
1303             --  the Interrupt.
1304
1305             Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep;
1306             POP.Sleep (Self_ID, Interrupt_Server_Blocked_Interrupt_Sleep);
1307             Self_ID.Common.State := Runnable;
1308
1309          else
1310             --  A Handler or an Entry is installed. At this point all tasks
1311             --  mask for the Interrupt is masked. Catch the Interrupt using
1312             --  sigwait.
1313
1314             --  This task may wake up from sigwait by receiving an interrupt
1315             --  (Abort_Task_Interrupt) from the Interrupt_Manager for unbinding
1316             --  a Procedure Handler or an Entry. Or it could be a wake up
1317             --  from status change (Unblocked -> Blocked). If that is not
1318             --  the case, we should execute the attached Procedure or Entry.
1319
1320             Self_ID.Common.State := Interrupt_Server_Blocked_On_Event_Flag;
1321             POP.Unlock (Self_ID);
1322
1323             if Single_Lock then
1324                POP.Unlock_RTS;
1325             end if;
1326
1327             --  Avoid race condition when terminating application and
1328             --  System.Parameters.No_Abort is True.
1329
1330             if Parameters.No_Abort and then Self_ID.Pending_Action then
1331                Initialization.Do_Pending_Action (Self_ID);
1332             end if;
1333
1334             Ret_Interrupt :=
1335               Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access));
1336             Self_ID.Common.State := Runnable;
1337
1338             if Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt) then
1339
1340                --  Inform the Interrupt_Manager of wakeup from above sigwait
1341
1342                POP.Abort_Task (Interrupt_Manager_ID);
1343
1344                if Single_Lock then
1345                   POP.Lock_RTS;
1346                end if;
1347
1348                POP.Write_Lock (Self_ID);
1349
1350             else
1351                if Single_Lock then
1352                   POP.Lock_RTS;
1353                end if;
1354
1355                POP.Write_Lock (Self_ID);
1356
1357                if Ret_Interrupt /= Interrupt then
1358
1359                   --  On some systems (e.g. recent linux kernels), sigwait
1360                   --  may return unexpectedly (with errno set to EINTR).
1361
1362                   null;
1363
1364                else
1365                   --  Even though we have received an Interrupt the status may
1366                   --  have changed already before we got the Self_ID lock above
1367                   --  Therefore we make sure a Handler or an Entry is still
1368                   --  there and make appropriate call.
1369
1370                   --  If there is no calls to make we need to regenerate the
1371                   --  Interrupt in order not to lose it.
1372
1373                   if User_Handler (Interrupt).H /= null then
1374                      Tmp_Handler := User_Handler (Interrupt).H;
1375
1376                      --  RTS calls should not be made with self being locked
1377
1378                      POP.Unlock (Self_ID);
1379
1380                      if Single_Lock then
1381                         POP.Unlock_RTS;
1382                      end if;
1383
1384                      Tmp_Handler.all;
1385
1386                      if Single_Lock then
1387                         POP.Lock_RTS;
1388                      end if;
1389
1390                      POP.Write_Lock (Self_ID);
1391
1392                   elsif User_Entry (Interrupt).T /= Null_Task then
1393                      Tmp_ID := User_Entry (Interrupt).T;
1394                      Tmp_Entry_Index := User_Entry (Interrupt).E;
1395
1396                      --  RTS calls should not be made with self being locked
1397
1398                      if Single_Lock then
1399                         POP.Unlock_RTS;
1400                      end if;
1401
1402                      POP.Unlock (Self_ID);
1403
1404                      System.Tasking.Rendezvous.Call_Simple
1405                        (Tmp_ID, Tmp_Entry_Index, System.Null_Address);
1406
1407                      POP.Write_Lock (Self_ID);
1408
1409                      if Single_Lock then
1410                         POP.Lock_RTS;
1411                      end if;
1412
1413                   else
1414                      --  This is a situation that this task wakes up receiving
1415                      --  an Interrupt and before it gets the lock the Interrupt
1416                      --  is blocked. We do not want to lose the interrupt in
1417                      --  this case so we regenerate the Interrupt to process
1418                      --  level.
1419
1420                      IMOP.Interrupt_Self_Process
1421                        (IMNG.Interrupt_ID (Interrupt));
1422                   end if;
1423                end if;
1424             end if;
1425          end if;
1426
1427          POP.Unlock (Self_ID);
1428
1429          if Single_Lock then
1430             POP.Unlock_RTS;
1431          end if;
1432
1433          System.Tasking.Initialization.Undefer_Abort (Self_ID);
1434
1435          if Self_ID.Pending_Action then
1436             Initialization.Do_Pending_Action (Self_ID);
1437          end if;
1438
1439          --  Undefer abort here to allow a window for this task to be aborted
1440          --  at the time of system shutdown. We also explicitly test for
1441          --  Pending_Action in case System.Parameters.No_Abort is True.
1442
1443       end loop;
1444    end Server_Task;
1445
1446 --  Elaboration code for package System.Interrupts
1447
1448 begin
1449    --  Get Interrupt_Manager's ID so that Abort_Interrupt can be sent
1450
1451    Interrupt_Manager_ID := To_System (Interrupt_Manager'Identity);
1452
1453    --  During the elaboration of this package body we want the RTS
1454    --  to inherit the interrupt mask from the Environment Task.
1455
1456    IMOP.Setup_Interrupt_Mask;
1457
1458    --  The environment task should have gotten its mask from the enclosing
1459    --  process during the RTS start up. (See processing in s-inmaop.adb). Pass
1460    --  the Interrupt_Mask of the environment task to the Interrupt_Manager.
1461
1462    --  Note: At this point we know that all tasks are masked for non-reserved
1463    --  signals. Only the Interrupt_Manager will have masks set up differently
1464    --  inheriting the original environment task's mask.
1465
1466    Interrupt_Manager.Initialize (IMOP.Environment_Mask);
1467 end System.Interrupts;