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                                 --
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   9 --         Copyright (C) 1992-2008, Free Software Foundation, Inc.          --
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  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 --
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  27 -- covered by the  GNU Public License.                                      --
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  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 --  Invariants:
  35
  36 --  All user-handleable interrupts are masked at all times in all
  37 --  tasks/threads except possibly for the Interrupt_Manager task.
  38
  39 --  When a user task wants to have the effect of masking/unmasking an
  40 --  interrupt, it must call Block_Interrupt/Unblock_Interrupt, which
  41 --  will have the effect of unmasking/masking the interrupt in the
  42 --  Interrupt_Manager task.
  43
  44 --  Note : Direct calls to sigaction, sigprocmask, pthread_sigsetmask or any
  45 --  other low-level interface that changes the interrupt action or
  46 --  interrupt mask needs a careful thought.
  47 --  One may achieve the effect of system calls first masking RTS blocked
  48 --  (by calling Block_Interrupt) for the interrupt under consideration.
  49 --  This will make all the tasks in RTS blocked for the Interrupt.
  50
  51 --  Once we associate a Server_Task with an interrupt, the task never
  52 --  goes away, and we never remove the association.
  53
  54 --  There is no more than one interrupt per Server_Task and no more than
  55 --  one Server_Task per interrupt.
  56
  57 with Ada.Task_Identification;
  58
  59 with System.Task_Primitives;
  60 with System.Interrupt_Management;
  61
  62 with System.Interrupt_Management.Operations;
  63 pragma Elaborate_All (System.Interrupt_Management.Operations);
  64
  65 with System.Task_Primitives.Operations;
  66 with System.Task_Primitives.Interrupt_Operations;
  67 with System.Storage_Elements;
  68 with System.Tasking.Utilities;
  69
  70 with System.Tasking.Rendezvous;
  71 pragma Elaborate_All (System.Tasking.Rendezvous);
  72
  73 with System.Tasking.Initialization;
  74 with System.Parameters;
  75
  76 with Ada.Unchecked_Conversion;
  77
  78 package body System.Interrupts is
  79
  80    use Parameters;
  81    use Tasking;
  82
  83    package POP renames System.Task_Primitives.Operations;
  84    package PIO renames System.Task_Primitives.Interrupt_Operations;
  85    package IMNG renames System.Interrupt_Management;
  86    package IMOP renames System.Interrupt_Management.Operations;
  87
  88    function To_System is new Ada.Unchecked_Conversion
  89      (Ada.Task_Identification.Task_Id, Task_Id);
  90
  91    -----------------
  92    -- Local Tasks --
  93    -----------------
  94
  95    --  WARNING: System.Tasking.Stages performs calls to this task with
  96    --  low-level constructs. Do not change this spec without synchronizing it.
  97
  98    task Interrupt_Manager is
  99       entry Detach_Interrupt_Entries (T : Task_Id);
 100
 101       entry Initialize (Mask : IMNG.Interrupt_Mask);
 102
 103       entry Attach_Handler
 104         (New_Handler : Parameterless_Handler;
 105          Interrupt   : Interrupt_ID;
 106          Static      : Boolean;
 107          Restoration : Boolean := False);
 108
 109       entry Exchange_Handler
 110         (Old_Handler : out Parameterless_Handler;
 111          New_Handler : Parameterless_Handler;
 112          Interrupt   : Interrupt_ID;
 113          Static      : Boolean);
 114
 115       entry Detach_Handler
 116         (Interrupt   : Interrupt_ID;
 117          Static      : Boolean);
 118
 119       entry Bind_Interrupt_To_Entry
 120         (T         : Task_Id;
 121          E         : Task_Entry_Index;
 122          Interrupt : Interrupt_ID);
 123
 124       entry Block_Interrupt (Interrupt : Interrupt_ID);
 125
 126       entry Unblock_Interrupt (Interrupt : Interrupt_ID);
 127
 128       entry Ignore_Interrupt (Interrupt : Interrupt_ID);
 129
 130       entry Unignore_Interrupt (Interrupt : Interrupt_ID);
 131
 132       pragma Interrupt_Priority (System.Interrupt_Priority'Last);
 133    end Interrupt_Manager;
 134
 135    task type Server_Task (Interrupt : Interrupt_ID) is
 136       pragma Priority (System.Interrupt_Priority'Last);
 137       --  Note: the above pragma Priority is strictly speaking improper since
 138       --  it is outside the range of allowed priorities, but the compiler
 139       --  treats system units specially and does not apply this range checking
 140       --  rule to system units.
 141
 142    end Server_Task;
 143
 144    type Server_Task_Access is access Server_Task;
 145
 146    -------------------------------
 147    -- Local Types and Variables --
 148    -------------------------------
 149
 150    type Entry_Assoc is record
 151       T : Task_Id;
 152       E : Task_Entry_Index;
 153    end record;
 154
 155    type Handler_Assoc is record
 156       H      : Parameterless_Handler;
 157       Static : Boolean;   --  Indicates static binding;
 158    end record;
 159
 160    User_Handler : array (Interrupt_ID'Range) of Handler_Assoc :=
 161                     (others => (null, Static => False));
 162    pragma Volatile_Components (User_Handler);
 163    --  Holds the protected procedure handler (if any) and its Static
 164    --  information for each interrupt. A handler is a Static one if it is
 165    --  specified through the pragma Attach_Handler. Attach_Handler. Otherwise,
 166    --  not static)
 167
 168    User_Entry : array (Interrupt_ID'Range) of Entry_Assoc :=
 169                   (others => (T => Null_Task, E => Null_Task_Entry));
 170    pragma Volatile_Components (User_Entry);
 171    --  Holds the task and entry index (if any) for each interrupt
 172
 173    Blocked : array (Interrupt_ID'Range) of Boolean := (others => False);
 174    pragma Atomic_Components (Blocked);
 175    --  True iff the corresponding interrupt is blocked in the process level
 176
 177    Ignored : array (Interrupt_ID'Range) of Boolean := (others => False);
 178    pragma Atomic_Components (Ignored);
 179    --  True iff the corresponding interrupt is blocked in the process level
 180
 181    Last_Unblocker :
 182      array (Interrupt_ID'Range) of Task_Id := (others => Null_Task);
 183    pragma Atomic_Components (Last_Unblocker);
 184    --  Holds the ID of the last Task which Unblocked this Interrupt. It
 185    --  contains Null_Task if no tasks have ever requested the Unblocking
 186    --  operation or the Interrupt is currently Blocked.
 187
 188    Server_ID : array (Interrupt_ID'Range) of Task_Id :=
 189                  (others => Null_Task);
 190    pragma Atomic_Components (Server_ID);
 191    --  Holds the Task_Id of the Server_Task for each interrupt. Task_Id is
 192    --  needed to accomplish locking per Interrupt base. Also is needed to
 193    --  decide whether to create a new Server_Task.
 194
 195    --  Type and Head, Tail of the list containing Registered Interrupt
 196    --  Handlers. These definitions are used to register the handlers
 197    --  specified by the pragma Interrupt_Handler.
 198
 199    type Registered_Handler;
 200    type R_Link is access all Registered_Handler;
 201
 202    type Registered_Handler is record
 203       H    : System.Address := System.Null_Address;
 204       Next : R_Link := null;
 205    end record;
 206
 207    Registered_Handler_Head : R_Link := null;
 208    Registered_Handler_Tail : R_Link := null;
 209
 210    Access_Hold : Server_Task_Access;
 211    --  Variable used to allocate Server_Task using "new"
 212
 213    -----------------------
 214    -- Local Subprograms --
 215    -----------------------
 216
 217    function Is_Registered (Handler : Parameterless_Handler) return Boolean;
 218    --  See if the Handler has been "pragma"ed using Interrupt_Handler. Always
 219    --  consider a null handler as registered.
 220
 221    --------------------
 222    -- Attach_Handler --
 223    --------------------
 224
 225    --  Calling this procedure with New_Handler = null and Static = True means
 226    --  we want to detach the current handler regardless of the previous
 227    --  handler's binding status (i.e. do not care if it is a dynamic or static
 228    --  handler).
 229
 230    --  This option is needed so that during the finalization of a PO, we can
 231    --  detach handlers attached through pragma Attach_Handler.
 232
 233    procedure Attach_Handler
 234      (New_Handler : Parameterless_Handler;
 235       Interrupt   : Interrupt_ID;
 236       Static      : Boolean := False)
 237    is
 238    begin
 239       if Is_Reserved (Interrupt) then
 240          raise Program_Error with
 241            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 242       end if;
 243
 244       Interrupt_Manager.Attach_Handler (New_Handler, Interrupt, Static);
 245
 246    end Attach_Handler;
 247
 248    -----------------------------
 249    -- Bind_Interrupt_To_Entry --
 250    -----------------------------
 251
 252    --  This procedure raises a Program_Error if it tries to bind an interrupt
 253    --  to which an Entry or a Procedure is already bound.
 254
 255    procedure Bind_Interrupt_To_Entry
 256      (T       : Task_Id;
 257       E       : Task_Entry_Index;
 258       Int_Ref : System.Address)
 259    is
 260       Interrupt   : constant Interrupt_ID :=
 261                       Interrupt_ID (Storage_Elements.To_Integer (Int_Ref));
 262
 263    begin
 264       if Is_Reserved (Interrupt) then
 265          raise Program_Error with
 266            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 267       end if;
 268
 269       Interrupt_Manager.Bind_Interrupt_To_Entry (T, E, Interrupt);
 270    end Bind_Interrupt_To_Entry;
 271
 272    ---------------------
 273    -- Block_Interrupt --
 274    ---------------------
 275
 276    procedure Block_Interrupt (Interrupt : Interrupt_ID) is
 277    begin
 278       if Is_Reserved (Interrupt) then
 279          raise Program_Error with
 280            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 281       end if;
 282
 283       Interrupt_Manager.Block_Interrupt (Interrupt);
 284    end Block_Interrupt;
 285
 286    ---------------------
 287    -- Current_Handler --
 288    ---------------------
 289
 290    function Current_Handler
 291      (Interrupt : Interrupt_ID) return Parameterless_Handler
 292    is
 293    begin
 294       if Is_Reserved (Interrupt) then
 295          raise Program_Error with
 296            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 297       end if;
 298
 299       --  ??? Since Parameterless_Handler is not Atomic, the current
 300       --  implementation is wrong. We need a new service in Interrupt_Manager
 301       --  to ensure atomicity.
 302
 303       return User_Handler (Interrupt).H;
 304    end Current_Handler;
 305
 306    --------------------
 307    -- Detach_Handler --
 308    --------------------
 309
 310    --  Calling this procedure with Static = True means we want to Detach the
 311    --  current handler regardless of the previous handler's binding status
 312    --  (i.e. do not care if it is a dynamic or static handler).
 313
 314    --  This option is needed so that during the finalization of a PO, we can
 315    --  detach handlers attached through pragma Attach_Handler.
 316
 317    procedure Detach_Handler
 318      (Interrupt : Interrupt_ID;
 319       Static    : Boolean := False)
 320    is
 321    begin
 322       if Is_Reserved (Interrupt) then
 323          raise Program_Error with
 324            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 325       end if;
 326
 327       Interrupt_Manager.Detach_Handler (Interrupt, Static);
 328    end Detach_Handler;
 329
 330    ------------------------------
 331    -- Detach_Interrupt_Entries --
 332    ------------------------------
 333
 334    procedure Detach_Interrupt_Entries (T : Task_Id) is
 335    begin
 336       Interrupt_Manager.Detach_Interrupt_Entries (T);
 337    end Detach_Interrupt_Entries;
 338
 339    ----------------------
 340    -- Exchange_Handler --
 341    ----------------------
 342
 343    --  Calling this procedure with New_Handler = null and Static = True means
 344    --  we want to detach the current handler regardless of the previous
 345    --  handler's binding status (i.e. do not care if it is a dynamic or static
 346    --  handler).
 347
 348    --  This option is needed so that during the finalization of a PO, we can
 349    --  detach handlers attached through pragma Attach_Handler.
 350
 351    procedure Exchange_Handler
 352      (Old_Handler : out Parameterless_Handler;
 353       New_Handler : Parameterless_Handler;
 354       Interrupt   : Interrupt_ID;
 355       Static      : Boolean := False)
 356    is
 357    begin
 358       if Is_Reserved (Interrupt) then
 359          raise Program_Error with
 360            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 361       end if;
 362
 363       Interrupt_Manager.Exchange_Handler
 364         (Old_Handler, New_Handler, Interrupt, Static);
 365    end Exchange_Handler;
 366
 367    --------------
 368    -- Finalize --
 369    --------------
 370
 371    procedure Finalize (Object : in out Static_Interrupt_Protection) is
 372    begin
 373       --  ??? loop to be executed only when we're not doing library level
 374       --  finalization, since in this case all interrupt tasks are gone.
 375
 376       if not Interrupt_Manager'Terminated then
 377          for N in reverse Object.Previous_Handlers'Range loop
 378             Interrupt_Manager.Attach_Handler
 379               (New_Handler => Object.Previous_Handlers (N).Handler,
 380                Interrupt   => Object.Previous_Handlers (N).Interrupt,
 381                Static      => Object.Previous_Handlers (N).Static,
 382                Restoration => True);
 383          end loop;
 384       end if;
 385
 386       Tasking.Protected_Objects.Entries.Finalize
 387         (Tasking.Protected_Objects.Entries.Protection_Entries (Object));
 388    end Finalize;
 389
 390    -------------------------------------
 391    -- Has_Interrupt_Or_Attach_Handler --
 392    -------------------------------------
 393
 394    --  Need comments as to why these always return True ???
 395
 396    function Has_Interrupt_Or_Attach_Handler
 397      (Object : access Dynamic_Interrupt_Protection) return Boolean
 398    is
 399       pragma Unreferenced (Object);
 400    begin
 401       return True;
 402    end Has_Interrupt_Or_Attach_Handler;
 403
 404    function Has_Interrupt_Or_Attach_Handler
 405      (Object : access Static_Interrupt_Protection) return Boolean
 406    is
 407       pragma Unreferenced (Object);
 408    begin
 409       return True;
 410    end Has_Interrupt_Or_Attach_Handler;
 411
 412    ----------------------
 413    -- Ignore_Interrupt --
 414    ----------------------
 415
 416    procedure Ignore_Interrupt (Interrupt : Interrupt_ID) is
 417    begin
 418       if Is_Reserved (Interrupt) then
 419          raise Program_Error with
 420            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 421       end if;
 422
 423       Interrupt_Manager.Ignore_Interrupt (Interrupt);
 424    end Ignore_Interrupt;
 425
 426    ----------------------
 427    -- Install_Handlers --
 428    ----------------------
 429
 430    procedure Install_Handlers
 431      (Object       : access Static_Interrupt_Protection;
 432       New_Handlers : New_Handler_Array)
 433    is
 434    begin
 435       for N in New_Handlers'Range loop
 436
 437          --  We need a lock around this ???
 438
 439          Object.Previous_Handlers (N).Interrupt := New_Handlers (N).Interrupt;
 440          Object.Previous_Handlers (N).Static    := User_Handler
 441            (New_Handlers (N).Interrupt).Static;
 442
 443          --  We call Exchange_Handler and not directly Interrupt_Manager.
 444          --  Exchange_Handler so we get the Is_Reserved check.
 445
 446          Exchange_Handler
 447            (Old_Handler => Object.Previous_Handlers (N).Handler,
 448             New_Handler => New_Handlers (N).Handler,
 449             Interrupt   => New_Handlers (N).Interrupt,
 450             Static      => True);
 451       end loop;
 452    end Install_Handlers;
 453
 454    ---------------------------------
 455    -- Install_Restricted_Handlers --
 456    ---------------------------------
 457
 458    procedure Install_Restricted_Handlers (Handlers : New_Handler_Array) is
 459    begin
 460       for N in Handlers'Range loop
 461          Attach_Handler (Handlers (N).Handler, Handlers (N).Interrupt, True);
 462       end loop;
 463    end Install_Restricted_Handlers;
 464
 465    ----------------
 466    -- Is_Blocked --
 467    ----------------
 468
 469    function Is_Blocked (Interrupt : Interrupt_ID) return Boolean is
 470    begin
 471       if Is_Reserved (Interrupt) then
 472          raise Program_Error with
 473            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 474       end if;
 475
 476       return Blocked (Interrupt);
 477    end Is_Blocked;
 478
 479    -----------------------
 480    -- Is_Entry_Attached --
 481    -----------------------
 482
 483    function Is_Entry_Attached (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 User_Entry (Interrupt).T /= Null_Task;
 491    end Is_Entry_Attached;
 492
 493    -------------------------
 494    -- Is_Handler_Attached --
 495    -------------------------
 496
 497    function Is_Handler_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_Handler (Interrupt).H /= null;
 505    end Is_Handler_Attached;
 506
 507    ----------------
 508    -- Is_Ignored --
 509    ----------------
 510
 511    function Is_Ignored (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 Ignored (Interrupt);
 519    end Is_Ignored;
 520
 521    -------------------
 522    -- Is_Registered --
 523    -------------------
 524
 525    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
 526
 527       type Fat_Ptr is record
 528          Object_Addr  : System.Address;
 529          Handler_Addr : System.Address;
 530       end record;
 531
 532       function To_Fat_Ptr is new Ada.Unchecked_Conversion
 533         (Parameterless_Handler, Fat_Ptr);
 534
 535       Ptr : R_Link;
 536       Fat : Fat_Ptr;
 537
 538    begin
 539       if Handler = null then
 540          return True;
 541       end if;
 542
 543       Fat := To_Fat_Ptr (Handler);
 544
 545       Ptr := Registered_Handler_Head;
 546
 547       while Ptr /= null loop
 548          if Ptr.H = Fat.Handler_Addr then
 549             return True;
 550          end if;
 551
 552          Ptr := Ptr.Next;
 553       end loop;
 554
 555       return False;
 556    end Is_Registered;
 557
 558    -----------------
 559    -- Is_Reserved --
 560    -----------------
 561
 562    function Is_Reserved (Interrupt : Interrupt_ID) return Boolean is
 563    begin
 564       return IMNG.Reserve (IMNG.Interrupt_ID (Interrupt));
 565    end Is_Reserved;
 566
 567    ---------------
 568    -- Reference --
 569    ---------------
 570
 571    function Reference (Interrupt : Interrupt_ID) return System.Address is
 572    begin
 573       if Is_Reserved (Interrupt) then
 574          raise Program_Error with
 575            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 576       end if;
 577
 578       return Storage_Elements.To_Address
 579         (Storage_Elements.Integer_Address (Interrupt));
 580    end Reference;
 581
 582    ---------------------------------
 583    -- Register_Interrupt_Handler  --
 584    ---------------------------------
 585
 586    procedure Register_Interrupt_Handler (Handler_Addr : System.Address) is
 587       New_Node_Ptr : R_Link;
 588
 589    begin
 590       --  This routine registers the Handler as usable for Dynamic Interrupt
 591       --  Handler. Routines attaching and detaching Handler dynamically should
 592       --  first consult if the Handler is registered. A Program Error should
 593       --  be raised if it is not registered.
 594
 595       --  The pragma Interrupt_Handler can only appear in the library level PO
 596       --  definition and instantiation. Therefore, we do not need to implement
 597       --  Unregistering operation. Neither we need to protect the queue
 598       --  structure using a Lock.
 599
 600       pragma Assert (Handler_Addr /= System.Null_Address);
 601
 602       New_Node_Ptr := new Registered_Handler;
 603       New_Node_Ptr.H := Handler_Addr;
 604
 605       if Registered_Handler_Head = null then
 606          Registered_Handler_Head := New_Node_Ptr;
 607          Registered_Handler_Tail := New_Node_Ptr;
 608
 609       else
 610          Registered_Handler_Tail.Next := New_Node_Ptr;
 611          Registered_Handler_Tail := New_Node_Ptr;
 612       end if;
 613    end Register_Interrupt_Handler;
 614
 615    -----------------------
 616    -- Unblock_Interrupt --
 617    -----------------------
 618
 619    procedure Unblock_Interrupt (Interrupt : Interrupt_ID) is
 620    begin
 621       if Is_Reserved (Interrupt) then
 622          raise Program_Error with
 623            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 624       end if;
 625
 626       Interrupt_Manager.Unblock_Interrupt (Interrupt);
 627    end Unblock_Interrupt;
 628
 629    ------------------
 630    -- Unblocked_By --
 631    ------------------
 632
 633    function Unblocked_By
 634      (Interrupt : Interrupt_ID) return System.Tasking.Task_Id
 635    is
 636    begin
 637       if Is_Reserved (Interrupt) then
 638          raise Program_Error with
 639            "Interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved";
 640       end if;
 641
 642       return Last_Unblocker (Interrupt);
 643    end Unblocked_By;
 644
 645    ------------------------
 646    -- Unignore_Interrupt --
 647    ------------------------
 648
 649    procedure Unignore_Interrupt (Interrupt : Interrupt_ID) 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       Interrupt_Manager.Unignore_Interrupt (Interrupt);
 657    end Unignore_Interrupt;
 658
 659    -----------------------
 660    -- Interrupt_Manager --
 661    -----------------------
 662
 663    task body Interrupt_Manager is
 664
 665       ---------------------
 666       -- Local Variables --
 667       ---------------------
 668
 669       Intwait_Mask  : aliased IMNG.Interrupt_Mask;
 670       Ret_Interrupt : Interrupt_ID;
 671       Old_Mask      : aliased IMNG.Interrupt_Mask;
 672       Old_Handler   : Parameterless_Handler;
 673
 674       --------------------
 675       -- Local Routines --
 676       --------------------
 677
 678       procedure Bind_Handler (Interrupt : Interrupt_ID);
 679       --  This procedure does not do anything if the Interrupt is blocked.
 680       --  Otherwise, we have to interrupt Server_Task for status change through
 681       --  Wakeup interrupt.
 682
 683       procedure Unbind_Handler (Interrupt : Interrupt_ID);
 684       --  This procedure does not do anything if the Interrupt is blocked.
 685       --  Otherwise, we have to interrupt Server_Task for status change
 686       --  through abort interrupt.
 687
 688       procedure Unprotected_Exchange_Handler
 689         (Old_Handler : out Parameterless_Handler;
 690          New_Handler : Parameterless_Handler;
 691          Interrupt   : Interrupt_ID;
 692          Static      : Boolean;
 693          Restoration : Boolean := False);
 694
 695       procedure Unprotected_Detach_Handler
 696         (Interrupt   : Interrupt_ID;
 697          Static      : Boolean);
 698
 699       ------------------
 700       -- Bind_Handler --
 701       ------------------
 702
 703       procedure Bind_Handler (Interrupt : Interrupt_ID) is
 704       begin
 705          if not Blocked (Interrupt) then
 706
 707             --  Mask this task for the given Interrupt so that all tasks
 708             --  are masked for the Interrupt and the actual delivery of the
 709             --  Interrupt will be caught using "sigwait" by the
 710             --  corresponding Server_Task.
 711
 712             IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt));
 713
 714             --  We have installed a Handler or an Entry before we called
 715             --  this procedure. If the Handler Task is waiting to be awakened,
 716             --  do it here. Otherwise, the interrupt will be discarded.
 717
 718             POP.Wakeup (Server_ID (Interrupt), Interrupt_Server_Idle_Sleep);
 719          end if;
 720       end Bind_Handler;
 721
 722       --------------------
 723       -- Unbind_Handler --
 724       --------------------
 725
 726       procedure Unbind_Handler (Interrupt : Interrupt_ID) is
 727          Server : System.Tasking.Task_Id;
 728       begin
 729          if not Blocked (Interrupt) then
 730             --  Currently, there is a Handler or an Entry attached and
 731             --  corresponding Server_Task is waiting on "sigwait."
 732             --  We have to wake up the Server_Task and make it
 733             --  wait on condition variable by sending an
 734             --  Abort_Task_Interrupt
 735
 736             Server := Server_ID (Interrupt);
 737
 738             case Server.Common.State is
 739                when Interrupt_Server_Idle_Sleep |
 740                     Interrupt_Server_Blocked_Interrupt_Sleep
 741                =>
 742                   POP.Wakeup (Server, Server.Common.State);
 743
 744                when Interrupt_Server_Blocked_On_Event_Flag =>
 745                   POP.Abort_Task (Server);
 746
 747                   --  Make sure corresponding Server_Task is out of its
 748                   --  own sigwait state.
 749
 750                   Ret_Interrupt :=
 751                     Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access));
 752                   pragma Assert
 753                     (Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt));
 754
 755                when Runnable =>
 756                   null;
 757
 758                when others =>
 759                   pragma Assert (False);
 760                   null;
 761             end case;
 762
 763             IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
 764
 765             --  Unmake the Interrupt for this task in order to allow default
 766             --  action again.
 767
 768             IMOP.Thread_Unblock_Interrupt (IMNG.Interrupt_ID (Interrupt));
 769
 770          else
 771             IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
 772          end if;
 773       end Unbind_Handler;
 774
 775       --------------------------------
 776       -- Unprotected_Detach_Handler --
 777       --------------------------------
 778
 779       procedure Unprotected_Detach_Handler
 780         (Interrupt   : Interrupt_ID;
 781          Static      : Boolean)
 782       is
 783          Old_Handler : Parameterless_Handler;
 784
 785       begin
 786          if User_Entry (Interrupt).T /= Null_Task then
 787
 788             --  In case we have an Interrupt Entry installed.
 789             --  raise a program error. (propagate it to the caller).
 790
 791             raise Program_Error with
 792               "An interrupt entry is already installed";
 793          end if;
 794
 795          --  Note : Static = True will pass the following check. That is the
 796          --  case when we want to detach a handler regardless of the static
 797          --  status of the current_Handler.
 798
 799          if not Static and then User_Handler (Interrupt).Static then
 800
 801             --  Tries to detach a static Interrupt Handler.
 802             --  raise a program error.
 803
 804             raise Program_Error with
 805               "Trying to detach a static Interrupt Handler";
 806          end if;
 807
 808          --  The interrupt should no longer be ignored if
 809          --  it was ever ignored.
 810
 811          Ignored (Interrupt) := False;
 812
 813          Old_Handler := User_Handler (Interrupt).H;
 814
 815          --  The new handler
 816
 817          User_Handler (Interrupt).H := null;
 818          User_Handler (Interrupt).Static := False;
 819
 820          if Old_Handler /= null then
 821             Unbind_Handler (Interrupt);
 822          end if;
 823       end Unprotected_Detach_Handler;
 824
 825       ----------------------------------
 826       -- Unprotected_Exchange_Handler --
 827       ----------------------------------
 828
 829       procedure Unprotected_Exchange_Handler
 830         (Old_Handler : out Parameterless_Handler;
 831          New_Handler : Parameterless_Handler;
 832          Interrupt   : Interrupt_ID;
 833          Static      : Boolean;
 834          Restoration : Boolean := False)
 835       is
 836       begin
 837          if User_Entry (Interrupt).T /= Null_Task then
 838
 839             --  In case we have an Interrupt Entry already installed.
 840             --  raise a program error. (propagate it to the caller).
 841
 842             raise Program_Error with
 843               "An interrupt is already installed";
 844          end if;
 845
 846          --  Note : A null handler with Static = True will pass the
 847          --  following check. That is the case when we want to Detach a
 848          --  handler regardless of the Static status of the current_Handler.
 849
 850          --  We don't check anything if Restoration is True, since we
 851          --  may be detaching a static handler to restore a dynamic one.
 852
 853          if not Restoration and then not Static
 854
 855             --  Tries to overwrite a static Interrupt Handler with a
 856             --  dynamic Handler
 857
 858            and then (User_Handler (Interrupt).Static
 859
 860                         --  The new handler is not specified as an
 861                         --  Interrupt Handler by a pragma.
 862
 863                         or else not Is_Registered (New_Handler))
 864          then
 865             raise Program_Error with
 866               "Trying to overwrite a static Interrupt Handler with a " &
 867               "dynamic Handler";
 868          end if;
 869
 870          --  The interrupt should no longer be ignored if
 871          --  it was ever ignored.
 872
 873          Ignored (Interrupt) := False;
 874
 875          --  Save the old handler
 876
 877          Old_Handler := User_Handler (Interrupt).H;
 878
 879          --  The new handler
 880
 881          User_Handler (Interrupt).H := New_Handler;
 882
 883          if New_Handler = null then
 884
 885             --  The null handler means we are detaching the handler
 886
 887             User_Handler (Interrupt).Static := False;
 888
 889          else
 890             User_Handler (Interrupt).Static := Static;
 891          end if;
 892
 893          --  Invoke a corresponding Server_Task if not yet created.
 894          --  Place Task_Id info in Server_ID array.
 895
 896          if Server_ID (Interrupt) = Null_Task then
 897
 898             --  When a new Server_Task is created, it should have its
 899             --  signal mask set to the All_Tasks_Mask.
 900
 901             IMOP.Set_Interrupt_Mask
 902               (IMOP.All_Tasks_Mask'Access, Old_Mask'Access);
 903             Access_Hold := new Server_Task (Interrupt);
 904             IMOP.Set_Interrupt_Mask (Old_Mask'Access);
 905
 906             Server_ID (Interrupt) := To_System (Access_Hold.all'Identity);
 907          end if;
 908
 909          if New_Handler = null then
 910             if Old_Handler /= null then
 911                Unbind_Handler (Interrupt);
 912             end if;
 913
 914             return;
 915          end if;
 916
 917          if Old_Handler = null then
 918             Bind_Handler (Interrupt);
 919          end if;
 920       end Unprotected_Exchange_Handler;
 921
 922    --  Start of processing for Interrupt_Manager
 923
 924    begin
 925       --  By making this task independent of master, when the process
 926       --  goes away, the Interrupt_Manager will terminate gracefully.
 927
 928       System.Tasking.Utilities.Make_Independent;
 929
 930       --  Environment task gets its own interrupt mask, saves it,
 931       --  and then masks all interrupts except the Keep_Unmasked set.
 932
 933       --  During rendezvous, the Interrupt_Manager receives the old
 934       --  interrupt mask of the environment task, and sets its own
 935       --  interrupt mask to that value.
 936
 937       --  The environment task will call the entry of Interrupt_Manager some
 938       --  during elaboration of the body of this package.
 939
 940       accept Initialize (Mask : IMNG.Interrupt_Mask) do
 941          declare
 942             The_Mask : aliased IMNG.Interrupt_Mask;
 943
 944          begin
 945             IMOP.Copy_Interrupt_Mask (The_Mask, Mask);
 946             IMOP.Set_Interrupt_Mask (The_Mask'Access);
 947          end;
 948       end Initialize;
 949
 950       --  Note: All tasks in RTS will have all the Reserve Interrupts
 951       --  being masked (except the Interrupt_Manager) and Keep_Unmasked
 952       --  unmasked when created.
 953
 954       --  Abort_Task_Interrupt is one of the Interrupt unmasked
 955       --  in all tasks. We mask the Interrupt in this particular task
 956       --  so that "sigwait" is possible to catch an explicitly sent
 957       --  Abort_Task_Interrupt from the Server_Tasks.
 958
 959       --  This sigwaiting is needed so that we make sure a Server_Task is
 960       --  out of its own sigwait state. This extra synchronization is
 961       --  necessary to prevent following scenarios.
 962
 963       --   1) Interrupt_Manager sends an Abort_Task_Interrupt to the
 964       --      Server_Task then changes its own interrupt mask (OS level).
 965       --      If an interrupt (corresponding to the Server_Task) arrives
 966       --      in the mean time we have the Interrupt_Manager unmasked and
 967       --      the Server_Task waiting on sigwait.
 968
 969       --   2) For unbinding handler, we install a default action in the
 970       --      Interrupt_Manager. POSIX.1c states that the result of using
 971       --      "sigwait" and "sigaction" simultaneously on the same interrupt
 972       --      is undefined. Therefore, we need to be informed from the
 973       --      Server_Task of the fact that the Server_Task is out of its
 974       --      sigwait stage.
 975
 976       IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access);
 977       IMOP.Add_To_Interrupt_Mask
 978         (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt);
 979       IMOP.Thread_Block_Interrupt
 980         (IMNG.Abort_Task_Interrupt);
 981
 982       loop
 983          --  A block is needed to absorb Program_Error exception
 984
 985          begin
 986             select
 987                accept Attach_Handler
 988                   (New_Handler : Parameterless_Handler;
 989                    Interrupt   : Interrupt_ID;
 990                    Static      : Boolean;
 991                    Restoration : Boolean := False)
 992                do
 993                   Unprotected_Exchange_Handler
 994                     (Old_Handler, New_Handler, Interrupt, Static, Restoration);
 995                end Attach_Handler;
 996
 997             or
 998                accept Exchange_Handler
 999                   (Old_Handler : out Parameterless_Handler;
1000                    New_Handler : Parameterless_Handler;
1001                    Interrupt   : Interrupt_ID;
1002                    Static      : Boolean)
1003                do
1004                   Unprotected_Exchange_Handler
1005                     (Old_Handler, New_Handler, Interrupt, Static);
1006                end Exchange_Handler;
1007
1008             or
1009                accept Detach_Handler
1010                  (Interrupt   : Interrupt_ID;
1011                   Static      : Boolean)
1012                do
1013                   Unprotected_Detach_Handler (Interrupt, Static);
1014                end Detach_Handler;
1015
1016             or
1017                accept Bind_Interrupt_To_Entry
1018                  (T       : Task_Id;
1019                   E       : Task_Entry_Index;
1020                   Interrupt : Interrupt_ID)
1021                do
1022                   --  if there is a binding already (either a procedure or an
1023                   --  entry), raise Program_Error (propagate it to the caller).
1024
1025                   if User_Handler (Interrupt).H /= null
1026                     or else User_Entry (Interrupt).T /= Null_Task
1027                   then
1028                      raise Program_Error with
1029                        "A binding for this interrupt is already present";
1030                   end if;
1031
1032                   --  The interrupt should no longer be ignored if
1033                   --  it was ever ignored.
1034
1035                   Ignored (Interrupt) := False;
1036                   User_Entry (Interrupt) := Entry_Assoc'(T => T, E => E);
1037
1038                   --  Indicate the attachment of Interrupt Entry in ATCB.
1039                   --  This is need so that when an Interrupt Entry task
1040                   --  terminates the binding can be cleaned. The call to
1041                   --  unbinding must be made by the task before it terminates.
1042
1043                   T.Interrupt_Entry := True;
1044
1045                   --  Invoke a corresponding Server_Task if not yet created.
1046                   --  Place Task_Id info in Server_ID array.
1047
1048                   if Server_ID (Interrupt) = Null_Task then
1049
1050                      --  When a new Server_Task is created, it should have its
1051                      --  signal mask set to the All_Tasks_Mask.
1052
1053                      IMOP.Set_Interrupt_Mask
1054                        (IMOP.All_Tasks_Mask'Access, Old_Mask'Access);
1055                      Access_Hold := new Server_Task (Interrupt);
1056                      IMOP.Set_Interrupt_Mask (Old_Mask'Access);
1057                      Server_ID (Interrupt) :=
1058                        To_System (Access_Hold.all'Identity);
1059                   end if;
1060
1061                   Bind_Handler (Interrupt);
1062                end Bind_Interrupt_To_Entry;
1063
1064             or
1065                accept Detach_Interrupt_Entries (T : Task_Id) do
1066                   for J in Interrupt_ID'Range loop
1067                      if not Is_Reserved (J) then
1068                         if User_Entry (J).T = T then
1069
1070                            --  The interrupt should no longer be ignored if
1071                            --  it was ever ignored.
1072
1073                            Ignored (J) := False;
1074                            User_Entry (J) := Entry_Assoc'
1075                              (T => Null_Task, E => Null_Task_Entry);
1076                            Unbind_Handler (J);
1077                         end if;
1078                      end if;
1079                   end loop;
1080
1081                   --  Indicate in ATCB that no Interrupt Entries are attached
1082
1083                   T.Interrupt_Entry := False;
1084                end Detach_Interrupt_Entries;
1085
1086             or
1087                accept Block_Interrupt (Interrupt : Interrupt_ID) do
1088                   if Blocked (Interrupt) then
1089                      return;
1090                   end if;
1091
1092                   Blocked (Interrupt) := True;
1093                   Last_Unblocker (Interrupt) := Null_Task;
1094
1095                   --  Mask this task for the given Interrupt so that all tasks
1096                   --  are masked for the Interrupt.
1097
1098                   IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt));
1099
1100                   if User_Handler (Interrupt).H /= null
1101                     or else User_Entry (Interrupt).T /= Null_Task
1102                   then
1103                      --  This is the case where the Server_Task is waiting
1104                      --  on "sigwait." Wake it up by sending an
1105                      --  Abort_Task_Interrupt so that the Server_Task
1106                      --  waits on Cond.
1107
1108                      POP.Abort_Task (Server_ID (Interrupt));
1109
1110                      --  Make sure corresponding Server_Task is out of its own
1111                      --  sigwait state.
1112
1113                      Ret_Interrupt := Interrupt_ID
1114                        (IMOP.Interrupt_Wait (Intwait_Mask'Access));
1115                      pragma Assert
1116                        (Ret_Interrupt =
1117                         Interrupt_ID (IMNG.Abort_Task_Interrupt));
1118                   end if;
1119                end Block_Interrupt;
1120
1121             or
1122                accept Unblock_Interrupt (Interrupt : Interrupt_ID) do
1123                   if not Blocked (Interrupt) then
1124                      return;
1125                   end if;
1126
1127                   Blocked (Interrupt) := False;
1128                   Last_Unblocker (Interrupt) :=
1129                     To_System (Unblock_Interrupt'Caller);
1130
1131                   if User_Handler (Interrupt).H = null
1132                     and then User_Entry (Interrupt).T = Null_Task
1133                   then
1134                      --  No handler is attached. Unmask the Interrupt so that
1135                      --  the default action can be carried out.
1136
1137                      IMOP.Thread_Unblock_Interrupt
1138                        (IMNG.Interrupt_ID (Interrupt));
1139
1140                   else
1141                      --  The Server_Task must be waiting on the Cond variable
1142                      --  since it was being blocked and an Interrupt Hander or
1143                      --  an Entry was there. Wake it up and let it change
1144                      --  it place of waiting according to its new state.
1145
1146                      POP.Wakeup (Server_ID (Interrupt),
1147                        Interrupt_Server_Blocked_Interrupt_Sleep);
1148                   end if;
1149                end Unblock_Interrupt;
1150
1151             or
1152                accept Ignore_Interrupt (Interrupt : Interrupt_ID) do
1153                   if Ignored (Interrupt) then
1154                      return;
1155                   end if;
1156
1157                   Ignored (Interrupt) := True;
1158
1159                   --  If there is a handler associated with the Interrupt,
1160                   --  detach it first. In this way we make sure that the
1161                   --  Server_Task is not on sigwait. This is legal since
1162                   --  Unignore_Interrupt is to install the default action.
1163
1164                   if User_Handler (Interrupt).H /= null then
1165                      Unprotected_Detach_Handler
1166                        (Interrupt => Interrupt, Static => True);
1167
1168                   elsif User_Entry (Interrupt).T /= Null_Task then
1169                      User_Entry (Interrupt) := Entry_Assoc'
1170                        (T => Null_Task, E => Null_Task_Entry);
1171                      Unbind_Handler (Interrupt);
1172                   end if;
1173
1174                   IMOP.Install_Ignore_Action (IMNG.Interrupt_ID (Interrupt));
1175                end Ignore_Interrupt;
1176
1177             or
1178                accept Unignore_Interrupt (Interrupt : Interrupt_ID) do
1179                   Ignored (Interrupt) := False;
1180
1181                   --  If there is a handler associated with the Interrupt,
1182                   --  detach it first. In this way we make sure that the
1183                   --  Server_Task is not on sigwait. This is legal since
1184                   --  Unignore_Interrupt is to install the default action.
1185
1186                   if User_Handler (Interrupt).H /= null then
1187                      Unprotected_Detach_Handler
1188                        (Interrupt => Interrupt, Static => True);
1189
1190                   elsif User_Entry (Interrupt).T /= Null_Task then
1191                      User_Entry (Interrupt) := Entry_Assoc'
1192                        (T => Null_Task, E => Null_Task_Entry);
1193                      Unbind_Handler (Interrupt);
1194                   end if;
1195
1196                   IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
1197                end Unignore_Interrupt;
1198             end select;
1199
1200          exception
1201             --  If there is a program error we just want to propagate it to
1202             --  the caller and do not want to stop this task.
1203
1204             when Program_Error =>
1205                null;
1206
1207             when others =>
1208                pragma Assert (False);
1209                null;
1210          end;
1211       end loop;
1212    end Interrupt_Manager;
1213
1214    -----------------
1215    -- Server_Task --
1216    -----------------
1217
1218    task body Server_Task is
1219       Intwait_Mask    : aliased IMNG.Interrupt_Mask;
1220       Ret_Interrupt   : Interrupt_ID;
1221       Self_ID         : constant Task_Id := Self;
1222       Tmp_Handler     : Parameterless_Handler;
1223       Tmp_ID          : Task_Id;
1224       Tmp_Entry_Index : Task_Entry_Index;
1225
1226    begin
1227       --  By making this task independent of master, when the process
1228       --  goes away, the Server_Task will terminate gracefully.
1229
1230       System.Tasking.Utilities.Make_Independent;
1231
1232       --  Install default action in system level
1233
1234       IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
1235
1236       --  Note: All tasks in RTS will have all the Reserve Interrupts being
1237       --  masked (except the Interrupt_Manager) and Keep_Unmasked unmasked when
1238       --  created.
1239
1240       --  Abort_Task_Interrupt is one of the Interrupt unmasked in all tasks.
1241       --  We mask the Interrupt in this particular task so that "sigwait" is
1242       --  possible to catch an explicitly sent Abort_Task_Interrupt from the
1243       --  Interrupt_Manager.
1244
1245       --  There are two Interrupt interrupts that this task catch through
1246       --  "sigwait." One is the Interrupt this task is designated to catch
1247       --  in order to execute user handler or entry. The other one is the
1248       --  Abort_Task_Interrupt. This interrupt is being sent from the
1249       --  Interrupt_Manager to inform status changes (e.g: become Blocked,
1250       --  Handler or Entry is to be detached).
1251
1252       --  Prepare a mask to used for sigwait
1253
1254       IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access);
1255
1256       IMOP.Add_To_Interrupt_Mask
1257         (Intwait_Mask'Access, IMNG.Interrupt_ID (Interrupt));
1258
1259       IMOP.Add_To_Interrupt_Mask
1260         (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt);
1261
1262       IMOP.Thread_Block_Interrupt
1263         (IMNG.Abort_Task_Interrupt);
1264
1265       PIO.Set_Interrupt_ID (IMNG.Interrupt_ID (Interrupt), Self_ID);
1266
1267       loop
1268          System.Tasking.Initialization.Defer_Abort (Self_ID);
1269
1270          if Single_Lock then
1271             POP.Lock_RTS;
1272          end if;
1273
1274          POP.Write_Lock (Self_ID);
1275
1276          if User_Handler (Interrupt).H = null
1277            and then User_Entry (Interrupt).T = Null_Task
1278          then
1279             --  No Interrupt binding. If there is an interrupt,
1280             --  Interrupt_Manager will take default action.
1281
1282             Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep;
1283             POP.Sleep (Self_ID, Interrupt_Server_Idle_Sleep);
1284             Self_ID.Common.State := Runnable;
1285
1286          elsif Blocked (Interrupt) then
1287
1288             --  Interrupt is blocked. Stay here, so we won't catch
1289             --  the Interrupt.
1290
1291             Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep;
1292             POP.Sleep (Self_ID, Interrupt_Server_Blocked_Interrupt_Sleep);
1293             Self_ID.Common.State := Runnable;
1294
1295          else
1296             --  A Handler or an Entry is installed. At this point all tasks
1297             --  mask for the Interrupt is masked. Catch the Interrupt using
1298             --  sigwait.
1299
1300             --  This task may wake up from sigwait by receiving an interrupt
1301             --  (Abort_Task_Interrupt) from the Interrupt_Manager for unbinding
1302             --  a Procedure Handler or an Entry. Or it could be a wake up
1303             --  from status change (Unblocked -> Blocked). If that is not
1304             --  the case, we should execute the attached Procedure or Entry.
1305
1306             Self_ID.Common.State := Interrupt_Server_Blocked_On_Event_Flag;
1307             POP.Unlock (Self_ID);
1308
1309             if Single_Lock then
1310                POP.Unlock_RTS;
1311             end if;
1312
1313             --  Avoid race condition when terminating application and
1314             --  System.Parameters.No_Abort is True.
1315
1316             if Parameters.No_Abort and then Self_ID.Pending_Action then
1317                Initialization.Do_Pending_Action (Self_ID);
1318             end if;
1319
1320             Ret_Interrupt :=
1321               Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access));
1322             Self_ID.Common.State := Runnable;
1323
1324             if Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt) then
1325
1326                --  Inform the Interrupt_Manager of wakeup from above sigwait
1327
1328                POP.Abort_Task (Interrupt_Manager_ID);
1329
1330                if Single_Lock then
1331                   POP.Lock_RTS;
1332                end if;
1333
1334                POP.Write_Lock (Self_ID);
1335
1336             else
1337                if Single_Lock then
1338                   POP.Lock_RTS;
1339                end if;
1340
1341                POP.Write_Lock (Self_ID);
1342
1343                if Ret_Interrupt /= Interrupt then
1344
1345                   --  On some systems (e.g. recent linux kernels), sigwait
1346                   --  may return unexpectedly (with errno set to EINTR).
1347
1348                   null;
1349
1350                else
1351                   --  Even though we have received an Interrupt the status may
1352                   --  have changed already before we got the Self_ID lock above
1353                   --  Therefore we make sure a Handler or an Entry is still
1354                   --  there and make appropriate call.
1355
1356                   --  If there is no calls to make we need to regenerate the
1357                   --  Interrupt in order not to lose it.
1358
1359                   if User_Handler (Interrupt).H /= null then
1360                      Tmp_Handler := User_Handler (Interrupt).H;
1361
1362                      --  RTS calls should not be made with self being locked
1363
1364                      POP.Unlock (Self_ID);
1365
1366                      if Single_Lock then
1367                         POP.Unlock_RTS;
1368                      end if;
1369
1370                      Tmp_Handler.all;
1371
1372                      if Single_Lock then
1373                         POP.Lock_RTS;
1374                      end if;
1375
1376                      POP.Write_Lock (Self_ID);
1377
1378                   elsif User_Entry (Interrupt).T /= Null_Task then
1379                      Tmp_ID := User_Entry (Interrupt).T;
1380                      Tmp_Entry_Index := User_Entry (Interrupt).E;
1381
1382                      --  RTS calls should not be made with self being locked
1383
1384                      if Single_Lock then
1385                         POP.Unlock_RTS;
1386                      end if;
1387
1388                      POP.Unlock (Self_ID);
1389
1390                      System.Tasking.Rendezvous.Call_Simple
1391                        (Tmp_ID, Tmp_Entry_Index, System.Null_Address);
1392
1393                      POP.Write_Lock (Self_ID);
1394
1395                      if Single_Lock then
1396                         POP.Lock_RTS;
1397                      end if;
1398
1399                   else
1400                      --  This is a situation that this task wakes up receiving
1401                      --  an Interrupt and before it gets the lock the Interrupt
1402                      --  is blocked. We do not want to lose the interrupt in
1403                      --  this case so we regenerate the Interrupt to process
1404                      --  level.
1405
1406                      IMOP.Interrupt_Self_Process
1407                        (IMNG.Interrupt_ID (Interrupt));
1408                   end if;
1409                end if;
1410             end if;
1411          end if;
1412
1413          POP.Unlock (Self_ID);
1414
1415          if Single_Lock then
1416             POP.Unlock_RTS;
1417          end if;
1418
1419          System.Tasking.Initialization.Undefer_Abort (Self_ID);
1420
1421          if Self_ID.Pending_Action then
1422             Initialization.Do_Pending_Action (Self_ID);
1423          end if;
1424
1425          --  Undefer abort here to allow a window for this task to be aborted
1426          --  at the time of system shutdown. We also explicitly test for
1427          --  Pending_Action in case System.Parameters.No_Abort is True.
1428
1429       end loop;
1430    end Server_Task;
1431
1432 --  Elaboration code for package System.Interrupts
1433
1434 begin
1435    --  Get Interrupt_Manager's ID so that Abort_Interrupt can be sent
1436
1437    Interrupt_Manager_ID := To_System (Interrupt_Manager'Identity);
1438
1439    --  During the elaboration of this package body we want the RTS
1440    --  to inherit the interrupt mask from the Environment Task.
1441
1442    IMOP.Setup_Interrupt_Mask;
1443
1444    --  The environment task should have gotten its mask from the enclosing
1445    --  process during the RTS start up. (See processing in s-inmaop.adb). Pass
1446    --  the Interrupt_Mask of the environment task to the Interrupt_Manager.
1447
1448    --  Note: At this point we know that all tasks are masked for non-reserved
1449    --  signals. Only the Interrupt_Manager will have masks set up differently
1450    --  inheriting the original environment task's mask.
1451
1452    Interrupt_Manager.Initialize (IMOP.Environment_Mask);
1453 end System.Interrupts;