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------------------------------------------------------------------------------
--                                                                          --
--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
--                                                                          --
--     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --
--                                                                          --
--                                  B o d y                                 --
--                                                                          --
--         Copyright (C) 1992-2009, Free Software Foundation, Inc.          --
--                                                                          --
-- GNARL is free software; you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNARL was developed by the GNARL team at Florida State University.       --
-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
--                                                                          --
------------------------------------------------------------------------------
 
--  This is a Solaris (native) version of this package
 
--  This package contains all the GNULL primitives that interface directly with
--  the underlying OS.
 
pragma Polling (Off);
--  Turn off polling, we do not want ATC polling to take place during tasking
--  operations. It causes infinite loops and other problems.
 
with Ada.Unchecked_Deallocation;
 
with Interfaces.C;
 
with System.Tasking.Debug;
with System.Interrupt_Management;
with System.OS_Primitives;
with System.Task_Info;
 
pragma Warnings (Off);
with System.OS_Lib;
pragma Warnings (On);
 
with System.Soft_Links;
--  We use System.Soft_Links instead of System.Tasking.Initialization
--  because the later is a higher level package that we shouldn't depend on.
--  For example when using the restricted run time, it is replaced by
--  System.Tasking.Restricted.Stages.
 
package body System.Task_Primitives.Operations is
 
   package SSL renames System.Soft_Links;
 
   use System.Tasking.Debug;
   use System.Tasking;
   use Interfaces.C;
   use System.OS_Interface;
   use System.Parameters;
   use System.OS_Primitives;
 
   ----------------
   -- Local Data --
   ----------------
 
   --  The following are logically constants, but need to be initialized
   --  at run time.
 
   Environment_Task_Id : Task_Id;
   --  A variable to hold Task_Id for the environment task.
   --  If we use this variable to get the Task_Id, we need the following
   --  ATCB_Key only for non-Ada threads.
 
   Unblocked_Signal_Mask : aliased sigset_t;
   --  The set of signals that should unblocked in all tasks
 
   ATCB_Key : aliased thread_key_t;
   --  Key used to find the Ada Task_Id associated with a thread,
   --  at least for C threads unknown to the Ada run-time system.
 
   Single_RTS_Lock : aliased RTS_Lock;
   --  This is a lock to allow only one thread of control in the RTS at
   --  a time; it is used to execute in mutual exclusion from all other tasks.
   --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 
   Next_Serial_Number : Task_Serial_Number := 100;
   --  We start at 100, to reserve some special values for
   --  using in error checking.
   --  The following are internal configuration constants needed.
 
   Abort_Handler_Installed : Boolean := False;
   --  True if a handler for the abort signal is installed
 
   ----------------------
   -- Priority Support --
   ----------------------
 
   Priority_Ceiling_Emulation : constant Boolean := True;
   --  controls whether we emulate priority ceiling locking
 
   --  To get a scheduling close to annex D requirements, we use the real-time
   --  class provided for LWPs and map each task/thread to a specific and
   --  unique LWP (there is 1 thread per LWP, and 1 LWP per thread).
 
   --  The real time class can only be set when the process has root
   --  privileges, so in the other cases, we use the normal thread scheduling
   --  and priority handling.
 
   Using_Real_Time_Class : Boolean := False;
   --  indicates whether the real time class is being used (i.e. the process
   --  has root privileges).
 
   Prio_Param : aliased struct_pcparms;
   --  Hold priority info (Real_Time) initialized during the package
   --  elaboration.
 
   -----------------------------------
   -- External Configuration Values --
   -----------------------------------
 
   Time_Slice_Val : Integer;
   pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 
   Locking_Policy : Character;
   pragma Import (C, Locking_Policy, "__gl_locking_policy");
 
   Dispatching_Policy : Character;
   pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 
   Foreign_Task_Elaborated : aliased Boolean := True;
   --  Used to identified fake tasks (i.e., non-Ada Threads)
 
   -----------------------
   -- Local Subprograms --
   -----------------------
 
   function sysconf (name : System.OS_Interface.int) return processorid_t;
   pragma Import (C, sysconf, "sysconf");
 
   SC_NPROCESSORS_CONF : constant System.OS_Interface.int := 14;
 
   function Num_Procs
     (name : System.OS_Interface.int := SC_NPROCESSORS_CONF)
      return processorid_t renames sysconf;
 
   procedure Abort_Handler
     (Sig     : Signal;
      Code    : not null access siginfo_t;
      Context : not null access ucontext_t);
   --  Target-dependent binding of inter-thread Abort signal to
   --  the raising of the Abort_Signal exception.
   --  See also comments in 7staprop.adb
 
   ------------
   -- Checks --
   ------------
 
   function Check_Initialize_Lock
     (L     : Lock_Ptr;
      Level : Lock_Level) return Boolean;
   pragma Inline (Check_Initialize_Lock);
 
   function Check_Lock (L : Lock_Ptr) return Boolean;
   pragma Inline (Check_Lock);
 
   function Record_Lock (L : Lock_Ptr) return Boolean;
   pragma Inline (Record_Lock);
 
   function Check_Sleep (Reason : Task_States) return Boolean;
   pragma Inline (Check_Sleep);
 
   function Record_Wakeup
     (L      : Lock_Ptr;
      Reason : Task_States) return Boolean;
   pragma Inline (Record_Wakeup);
 
   function Check_Wakeup
     (T      : Task_Id;
      Reason : Task_States) return Boolean;
   pragma Inline (Check_Wakeup);
 
   function Check_Unlock (L : Lock_Ptr) return Boolean;
   pragma Inline (Check_Unlock);
 
   function Check_Finalize_Lock (L : Lock_Ptr) return Boolean;
   pragma Inline (Check_Finalize_Lock);
 
   --------------------
   -- Local Packages --
   --------------------
 
   package Specific is
 
      procedure Initialize (Environment_Task : Task_Id);
      pragma Inline (Initialize);
      --  Initialize various data needed by this package
 
      function Is_Valid_Task return Boolean;
      pragma Inline (Is_Valid_Task);
      --  Does executing thread have a TCB?
 
      procedure Set (Self_Id : Task_Id);
      pragma Inline (Set);
      --  Set the self id for the current task
 
      function Self return Task_Id;
      pragma Inline (Self);
      --  Return a pointer to the Ada Task Control Block of the calling task
 
   end Specific;
 
   package body Specific is separate;
   --  The body of this package is target specific
 
   ---------------------------------
   -- Support for foreign threads --
   ---------------------------------
 
   function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
   --  Allocate and Initialize a new ATCB for the current Thread
 
   function Register_Foreign_Thread
     (Thread : Thread_Id) return Task_Id is separate;
 
   ------------
   -- Checks --
   ------------
 
   Check_Count  : Integer := 0;
   Lock_Count   : Integer := 0;
   Unlock_Count : Integer := 0;
 
   -------------------
   -- Abort_Handler --
   -------------------
 
   procedure Abort_Handler
     (Sig     : Signal;
      Code    : not null access siginfo_t;
      Context : not null access ucontext_t)
   is
      pragma Unreferenced (Sig);
      pragma Unreferenced (Code);
      pragma Unreferenced (Context);
 
      Self_ID : constant Task_Id := Self;
      Old_Set : aliased sigset_t;
 
      Result : Interfaces.C.int;
      pragma Warnings (Off, Result);
 
   begin
      --  It's not safe to raise an exception when using GCC ZCX mechanism.
      --  Note that we still need to install a signal handler, since in some
      --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we
      --  need to send the Abort signal to a task.
 
      if ZCX_By_Default and then GCC_ZCX_Support then
         return;
      end if;
 
      if Self_ID.Deferral_Level = 0
        and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
        and then not Self_ID.Aborting
      then
         Self_ID.Aborting := True;
 
         --  Make sure signals used for RTS internal purpose are unmasked
 
         Result :=
           thr_sigsetmask
             (SIG_UNBLOCK,
              Unblocked_Signal_Mask'Unchecked_Access,
              Old_Set'Unchecked_Access);
         pragma Assert (Result = 0);
 
         raise Standard'Abort_Signal;
      end if;
   end Abort_Handler;
 
   -----------------
   -- Stack_Guard --
   -----------------
 
   --  The underlying thread system sets a guard page at the
   --  bottom of a thread stack, so nothing is needed.
 
   procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
      pragma Unreferenced (T);
      pragma Unreferenced (On);
   begin
      null;
   end Stack_Guard;
 
   -------------------
   -- Get_Thread_Id --
   -------------------
 
   function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
   begin
      return T.Common.LL.Thread;
   end Get_Thread_Id;
 
   ----------------
   -- Initialize --
   ----------------
 
   procedure Initialize (Environment_Task : ST.Task_Id) is
      act     : aliased struct_sigaction;
      old_act : aliased struct_sigaction;
      Tmp_Set : aliased sigset_t;
      Result  : Interfaces.C.int;
 
      procedure Configure_Processors;
      --  Processors configuration
      --  The user can specify a processor which the program should run
      --  on to emulate a single-processor system. This can be easily
      --  done by setting environment variable GNAT_PROCESSOR to one of
      --  the following :
      --
      --    -2 : use the default configuration (run the program on all
      --         available processors) - this is the same as having
      --         GNAT_PROCESSOR unset
      --    -1 : let the RTS choose one processor and run the program on
      --         that processor
      --    0 .. Last_Proc : run the program on the specified processor
      --
      --  Last_Proc is equal to the value of the system variable
      --  _SC_NPROCESSORS_CONF, minus one.
 
      procedure Configure_Processors is
         Proc_Acc  : constant System.OS_Lib.String_Access :=
                       System.OS_Lib.Getenv ("GNAT_PROCESSOR");
         Proc      : aliased processorid_t;  --  User processor #
         Last_Proc : processorid_t;          --  Last processor #
 
      begin
         if Proc_Acc.all'Length /= 0 then
 
            --  Environment variable is defined
 
            Last_Proc := Num_Procs - 1;
 
            if Last_Proc /= -1 then
               Proc := processorid_t'Value (Proc_Acc.all);
 
               if Proc <= -2  or else Proc > Last_Proc then
 
                  --  Use the default configuration
 
                  null;
 
               elsif Proc = -1 then
 
                  --  Choose a processor
 
                  Result := 0;
                  while Proc < Last_Proc loop
                     Proc := Proc + 1;
                     Result := p_online (Proc, PR_STATUS);
                     exit when Result = PR_ONLINE;
                  end loop;
 
                  pragma Assert (Result = PR_ONLINE);
                  Result := processor_bind (P_PID, P_MYID, Proc, null);
                  pragma Assert (Result = 0);
 
               else
                  --  Use user processor
 
                  Result := processor_bind (P_PID, P_MYID, Proc, null);
                  pragma Assert (Result = 0);
               end if;
            end if;
         end if;
 
      exception
         when Constraint_Error =>
 
            --  Illegal environment variable GNAT_PROCESSOR - ignored
 
            null;
      end Configure_Processors;
 
      function State
        (Int : System.Interrupt_Management.Interrupt_ID) return Character;
      pragma Import (C, State, "__gnat_get_interrupt_state");
      --  Get interrupt state.  Defined in a-init.c
      --  The input argument is the interrupt number,
      --  and the result is one of the following:
 
      Default : constant Character := 's';
      --    'n'   this interrupt not set by any Interrupt_State pragma
      --    'u'   Interrupt_State pragma set state to User
      --    'r'   Interrupt_State pragma set state to Runtime
      --    's'   Interrupt_State pragma set state to System (use "default"
      --           system handler)
 
   --  Start of processing for Initialize
 
   begin
      Environment_Task_Id := Environment_Task;
 
      Interrupt_Management.Initialize;
 
      --  Prepare the set of signals that should unblocked in all tasks
 
      Result := sigemptyset (Unblocked_Signal_Mask'Access);
      pragma Assert (Result = 0);
 
      for J in Interrupt_Management.Interrupt_ID loop
         if System.Interrupt_Management.Keep_Unmasked (J) then
            Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
            pragma Assert (Result = 0);
         end if;
      end loop;
 
      if Dispatching_Policy = 'F' then
         declare
            Result      : Interfaces.C.long;
            Class_Info  : aliased struct_pcinfo;
            Secs, Nsecs : Interfaces.C.long;
 
         begin
            --  If a pragma Time_Slice is specified, takes the value in account
 
            if Time_Slice_Val > 0 then
 
               --  Convert Time_Slice_Val (microseconds) to seconds/nanosecs
 
               Secs := Interfaces.C.long (Time_Slice_Val / 1_000_000);
               Nsecs :=
                 Interfaces.C.long ((Time_Slice_Val rem 1_000_000) * 1_000);
 
            --  Otherwise, default to no time slicing (i.e run until blocked)
 
            else
               Secs := RT_TQINF;
               Nsecs := RT_TQINF;
            end if;
 
            --  Get the real time class id
 
            Class_Info.pc_clname (1) := 'R';
            Class_Info.pc_clname (2) := 'T';
            Class_Info.pc_clname (3) := ASCII.NUL;
 
            Result := priocntl (PC_VERSION, P_LWPID, P_MYID, PC_GETCID,
              Class_Info'Address);
 
            --  Request the real time class
 
            Prio_Param.pc_cid := Class_Info.pc_cid;
            Prio_Param.rt_pri := pri_t (Class_Info.rt_maxpri);
            Prio_Param.rt_tqsecs := Secs;
            Prio_Param.rt_tqnsecs := Nsecs;
 
            Result :=
              priocntl
                (PC_VERSION, P_LWPID, P_MYID, PC_SETPARMS, Prio_Param'Address);
 
            Using_Real_Time_Class := Result /= -1;
         end;
      end if;
 
      Specific.Initialize (Environment_Task);
 
      --  The following is done in Enter_Task, but this is too late for the
      --  Environment Task, since we need to call Self in Check_Locks when
      --  the run time is compiled with assertions on.
 
      Specific.Set (Environment_Task);
 
      --  Initialize the lock used to synchronize chain of all ATCBs
 
      Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
 
      --  Make environment task known here because it doesn't go through
      --  Activate_Tasks, which does it for all other tasks.
 
      Known_Tasks (Known_Tasks'First) := Environment_Task;
      Environment_Task.Known_Tasks_Index := Known_Tasks'First;
 
      Enter_Task (Environment_Task);
 
      Configure_Processors;
 
      if State
          (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
      then
         --  Set sa_flags to SA_NODEFER so that during the handler execution
         --  we do not change the Signal_Mask to be masked for the Abort_Signal
         --  This is a temporary fix to the problem that the Signal_Mask is
         --  not restored after the exception (longjmp) from the handler.
         --  The right fix should be made in sigsetjmp so that we save
         --  the Signal_Set and restore it after a longjmp.
         --  In that case, this field should be changed back to 0. ???
 
         act.sa_flags := 16;
 
         act.sa_handler := Abort_Handler'Address;
         Result := sigemptyset (Tmp_Set'Access);
         pragma Assert (Result = 0);
         act.sa_mask := Tmp_Set;
 
         Result :=
           sigaction
             (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
              act'Unchecked_Access,
              old_act'Unchecked_Access);
         pragma Assert (Result = 0);
         Abort_Handler_Installed := True;
      end if;
   end Initialize;
 
   ---------------------
   -- Initialize_Lock --
   ---------------------
 
   --  Note: mutexes and cond_variables needed per-task basis are initialized
   --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such
   --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any
   --  status change of RTS. Therefore raising Storage_Error in the following
   --  routines should be able to be handled safely.
 
   procedure Initialize_Lock
     (Prio : System.Any_Priority;
      L    : not null access Lock)
   is
      Result : Interfaces.C.int;
 
   begin
      pragma Assert (Check_Initialize_Lock (Lock_Ptr (L), PO_Level));
 
      if Priority_Ceiling_Emulation then
         L.Ceiling := Prio;
      end if;
 
      Result := mutex_init (L.L'Access, USYNC_THREAD, System.Null_Address);
      pragma Assert (Result = 0 or else Result = ENOMEM);
 
      if Result = ENOMEM then
         raise Storage_Error with "Failed to allocate a lock";
      end if;
   end Initialize_Lock;
 
   procedure Initialize_Lock
     (L     : not null access RTS_Lock;
      Level : Lock_Level)
   is
      Result : Interfaces.C.int;
 
   begin
      pragma Assert
        (Check_Initialize_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L)), Level));
      Result := mutex_init (L.L'Access, USYNC_THREAD, System.Null_Address);
      pragma Assert (Result = 0 or else Result = ENOMEM);
 
      if Result = ENOMEM then
         raise Storage_Error with "Failed to allocate a lock";
      end if;
   end Initialize_Lock;
 
   -------------------
   -- Finalize_Lock --
   -------------------
 
   procedure Finalize_Lock (L : not null access Lock) is
      Result : Interfaces.C.int;
   begin
      pragma Assert (Check_Finalize_Lock (Lock_Ptr (L)));
      Result := mutex_destroy (L.L'Access);
      pragma Assert (Result = 0);
   end Finalize_Lock;
 
   procedure Finalize_Lock (L : not null access RTS_Lock) is
      Result : Interfaces.C.int;
   begin
      pragma Assert (Check_Finalize_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L))));
      Result := mutex_destroy (L.L'Access);
      pragma Assert (Result = 0);
   end Finalize_Lock;
 
   ----------------
   -- Write_Lock --
   ----------------
 
   procedure Write_Lock
     (L                 : not null access Lock;
      Ceiling_Violation : out Boolean)
   is
      Result : Interfaces.C.int;
 
   begin
      pragma Assert (Check_Lock (Lock_Ptr (L)));
 
      if Priority_Ceiling_Emulation and then Locking_Policy = 'C' then
         declare
            Self_Id        : constant Task_Id := Self;
            Saved_Priority : System.Any_Priority;
 
         begin
            if Self_Id.Common.LL.Active_Priority > L.Ceiling then
               Ceiling_Violation := True;
               return;
            end if;
 
            Saved_Priority := Self_Id.Common.LL.Active_Priority;
 
            if Self_Id.Common.LL.Active_Priority < L.Ceiling then
               Set_Priority (Self_Id, L.Ceiling);
            end if;
 
            Result := mutex_lock (L.L'Access);
            pragma Assert (Result = 0);
            Ceiling_Violation := False;
 
            L.Saved_Priority := Saved_Priority;
         end;
 
      else
         Result := mutex_lock (L.L'Access);
         pragma Assert (Result = 0);
         Ceiling_Violation := False;
      end if;
 
      pragma Assert (Record_Lock (Lock_Ptr (L)));
   end Write_Lock;
 
   procedure Write_Lock
     (L          : not null access RTS_Lock;
     Global_Lock : Boolean := False)
   is
      Result : Interfaces.C.int;
   begin
      if not Single_Lock or else Global_Lock then
         pragma Assert (Check_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L))));
         Result := mutex_lock (L.L'Access);
         pragma Assert (Result = 0);
         pragma Assert (Record_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L))));
      end if;
   end Write_Lock;
 
   procedure Write_Lock (T : Task_Id) is
      Result : Interfaces.C.int;
   begin
      if not Single_Lock then
         pragma Assert (Check_Lock (To_Lock_Ptr (T.Common.LL.L'Access)));
         Result := mutex_lock (T.Common.LL.L.L'Access);
         pragma Assert (Result = 0);
         pragma Assert (Record_Lock (To_Lock_Ptr (T.Common.LL.L'Access)));
      end if;
   end Write_Lock;
 
   ---------------
   -- Read_Lock --
   ---------------
 
   procedure Read_Lock
     (L                 : not null access Lock;
      Ceiling_Violation : out Boolean) is
   begin
      Write_Lock (L, Ceiling_Violation);
   end Read_Lock;
 
   ------------
   -- Unlock --
   ------------
 
   procedure Unlock (L : not null access Lock) is
      Result : Interfaces.C.int;
 
   begin
      pragma Assert (Check_Unlock (Lock_Ptr (L)));
 
      if Priority_Ceiling_Emulation and then Locking_Policy = 'C' then
         declare
            Self_Id : constant Task_Id := Self;
 
         begin
            Result := mutex_unlock (L.L'Access);
            pragma Assert (Result = 0);
 
            if Self_Id.Common.LL.Active_Priority > L.Saved_Priority then
               Set_Priority (Self_Id, L.Saved_Priority);
            end if;
         end;
      else
         Result := mutex_unlock (L.L'Access);
         pragma Assert (Result = 0);
      end if;
   end Unlock;
 
   procedure Unlock
     (L           : not null access RTS_Lock;
      Global_Lock : Boolean := False)
   is
      Result : Interfaces.C.int;
   begin
      if not Single_Lock or else Global_Lock then
         pragma Assert (Check_Unlock (To_Lock_Ptr (RTS_Lock_Ptr (L))));
         Result := mutex_unlock (L.L'Access);
         pragma Assert (Result = 0);
      end if;
   end Unlock;
 
   procedure Unlock (T : Task_Id) is
      Result : Interfaces.C.int;
   begin
      if not Single_Lock then
         pragma Assert (Check_Unlock (To_Lock_Ptr (T.Common.LL.L'Access)));
         Result := mutex_unlock (T.Common.LL.L.L'Access);
         pragma Assert (Result = 0);
      end if;
   end Unlock;
 
   -----------------
   -- Set_Ceiling --
   -----------------
 
   --  Dynamic priority ceilings are not supported by the underlying system
 
   procedure Set_Ceiling
     (L    : not null access Lock;
      Prio : System.Any_Priority)
   is
      pragma Unreferenced (L, Prio);
   begin
      null;
   end Set_Ceiling;
 
   --  For the time delay implementation, we need to make sure we
   --  achieve following criteria:
 
   --  1) We have to delay at least for the amount requested.
   --  2) We have to give up CPU even though the actual delay does not
   --     result in blocking.
   --  3) Except for restricted run-time systems that do not support
   --     ATC or task abort, the delay must be interrupted by the
   --     abort_task operation.
   --  4) The implementation has to be efficient so that the delay overhead
   --     is relatively cheap.
   --  (1)-(3) are Ada requirements. Even though (2) is an Annex-D
   --     requirement we still want to provide the effect in all cases.
   --     The reason is that users may want to use short delays to implement
   --     their own scheduling effect in the absence of language provided
   --     scheduling policies.
 
   ---------------------
   -- Monotonic_Clock --
   ---------------------
 
   function Monotonic_Clock return Duration is
      TS     : aliased timespec;
      Result : Interfaces.C.int;
   begin
      Result := clock_gettime (CLOCK_REALTIME, TS'Unchecked_Access);
      pragma Assert (Result = 0);
      return To_Duration (TS);
   end Monotonic_Clock;
 
   -------------------
   -- RT_Resolution --
   -------------------
 
   function RT_Resolution return Duration is
   begin
      return 10#1.0#E-6;
   end RT_Resolution;
 
   -----------
   -- Yield --
   -----------
 
   procedure Yield (Do_Yield : Boolean := True) is
   begin
      if Do_Yield then
         System.OS_Interface.thr_yield;
      end if;
   end Yield;
 
   -----------
   -- Self ---
   -----------
 
   function Self return Task_Id renames Specific.Self;
 
   ------------------
   -- Set_Priority --
   ------------------
 
   procedure Set_Priority
     (T                   : Task_Id;
      Prio                : System.Any_Priority;
      Loss_Of_Inheritance : Boolean := False)
   is
      pragma Unreferenced (Loss_Of_Inheritance);
 
      Result : Interfaces.C.int;
      pragma Unreferenced (Result);
 
      Param : aliased struct_pcparms;
 
      use Task_Info;
 
   begin
      T.Common.Current_Priority := Prio;
 
      if Priority_Ceiling_Emulation then
         T.Common.LL.Active_Priority := Prio;
      end if;
 
      if Using_Real_Time_Class then
         Param.pc_cid := Prio_Param.pc_cid;
         Param.rt_pri := pri_t (Prio);
         Param.rt_tqsecs := Prio_Param.rt_tqsecs;
         Param.rt_tqnsecs := Prio_Param.rt_tqnsecs;
 
         Result := Interfaces.C.int (
           priocntl (PC_VERSION, P_LWPID, T.Common.LL.LWP, PC_SETPARMS,
             Param'Address));
 
      else
         if T.Common.Task_Info /= null
           and then not T.Common.Task_Info.Bound_To_LWP
         then
            --  The task is not bound to a LWP, so use thr_setprio
 
            Result :=
              thr_setprio (T.Common.LL.Thread, Interfaces.C.int (Prio));
 
         else
            --  The task is bound to a LWP, use priocntl
            --  ??? TBD
 
            null;
         end if;
      end if;
   end Set_Priority;
 
   ------------------
   -- Get_Priority --
   ------------------
 
   function Get_Priority (T : Task_Id) return System.Any_Priority is
   begin
      return T.Common.Current_Priority;
   end Get_Priority;
 
   ----------------
   -- Enter_Task --
   ----------------
 
   procedure Enter_Task (Self_ID : Task_Id) is
      Result    : Interfaces.C.int;
      Proc      : processorid_t;  --  User processor #
      Last_Proc : processorid_t;  --  Last processor #
 
      use System.Task_Info;
   begin
      Self_ID.Common.LL.Thread := thr_self;
 
      Self_ID.Common.LL.LWP := lwp_self;
 
      if Self_ID.Common.Task_Info /= null then
         if Self_ID.Common.Task_Info.New_LWP
           and then Self_ID.Common.Task_Info.CPU /= CPU_UNCHANGED
         then
            Last_Proc := Num_Procs - 1;
 
            if Self_ID.Common.Task_Info.CPU = ANY_CPU then
               Result := 0;
               Proc := 0;
               while Proc < Last_Proc loop
                  Result := p_online (Proc, PR_STATUS);
                  exit when Result = PR_ONLINE;
                  Proc := Proc + 1;
               end loop;
 
               Result := processor_bind (P_LWPID, P_MYID, Proc, null);
               pragma Assert (Result = 0);
 
            else
               --  Use specified processor
 
               if Self_ID.Common.Task_Info.CPU < 0
                 or else Self_ID.Common.Task_Info.CPU > Last_Proc
               then
                  raise Invalid_CPU_Number;
               end if;
 
               Result :=
                 processor_bind
                   (P_LWPID, P_MYID, Self_ID.Common.Task_Info.CPU, null);
               pragma Assert (Result = 0);
            end if;
         end if;
      end if;
 
      Specific.Set (Self_ID);
 
      --  We need the above code even if we do direct fetch of Task_Id in Self
      --  for the main task on Sun, x86 Solaris and for gcc 2.7.2.
   end Enter_Task;
 
   --------------
   -- New_ATCB --
   --------------
 
   function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
   begin
      return new Ada_Task_Control_Block (Entry_Num);
   end New_ATCB;
 
   -------------------
   -- Is_Valid_Task --
   -------------------
 
   function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 
   -----------------------------
   -- Register_Foreign_Thread --
   -----------------------------
 
   function Register_Foreign_Thread return Task_Id is
   begin
      if Is_Valid_Task then
         return Self;
      else
         return Register_Foreign_Thread (thr_self);
      end if;
   end Register_Foreign_Thread;
 
   --------------------
   -- Initialize_TCB --
   --------------------
 
   procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
      Result : Interfaces.C.int := 0;
 
   begin
      --  Give the task a unique serial number
 
      Self_ID.Serial_Number := Next_Serial_Number;
      Next_Serial_Number := Next_Serial_Number + 1;
      pragma Assert (Next_Serial_Number /= 0);
 
      Self_ID.Common.LL.Thread := To_thread_t (-1);
 
      if not Single_Lock then
         Result :=
           mutex_init
             (Self_ID.Common.LL.L.L'Access, USYNC_THREAD, System.Null_Address);
         Self_ID.Common.LL.L.Level :=
           Private_Task_Serial_Number (Self_ID.Serial_Number);
         pragma Assert (Result = 0 or else Result = ENOMEM);
      end if;
 
      if Result = 0 then
         Result := cond_init (Self_ID.Common.LL.CV'Access, USYNC_THREAD, 0);
         pragma Assert (Result = 0 or else Result = ENOMEM);
      end if;
 
      if Result = 0 then
         Succeeded := True;
      else
         if not Single_Lock then
            Result := mutex_destroy (Self_ID.Common.LL.L.L'Access);
            pragma Assert (Result = 0);
         end if;
 
         Succeeded := False;
      end if;
   end Initialize_TCB;
 
   -----------------
   -- Create_Task --
   -----------------
 
   procedure Create_Task
     (T          : Task_Id;
      Wrapper    : System.Address;
      Stack_Size : System.Parameters.Size_Type;
      Priority   : System.Any_Priority;
      Succeeded  : out Boolean)
   is
      pragma Unreferenced (Priority);
 
      Result              : Interfaces.C.int;
      Adjusted_Stack_Size : Interfaces.C.size_t;
      Opts                : Interfaces.C.int := THR_DETACHED;
 
      Page_Size           : constant System.Parameters.Size_Type := 4096;
      --  This constant is for reserving extra space at the
      --  end of the stack, which can be used by the stack
      --  checking as guard page. The idea is that we need
      --  to have at least Stack_Size bytes available for
      --  actual use.
 
      use System.Task_Info;
 
   begin
      Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size + Page_Size);
 
      --  Since the initial signal mask of a thread is inherited from the
      --  creator, and the Environment task has all its signals masked, we
      --  do not need to manipulate caller's signal mask at this point.
      --  All tasks in RTS will have All_Tasks_Mask initially.
 
      if T.Common.Task_Info /= null then
         if T.Common.Task_Info.New_LWP then
            Opts := Opts + THR_NEW_LWP;
         end if;
 
         if T.Common.Task_Info.Bound_To_LWP then
            Opts := Opts + THR_BOUND;
         end if;
 
      else
         Opts := THR_DETACHED + THR_BOUND;
      end if;
 
      Result :=
        thr_create
          (System.Null_Address,
           Adjusted_Stack_Size,
           Thread_Body_Access (Wrapper),
           To_Address (T),
           Opts,
           T.Common.LL.Thread'Access);
 
      Succeeded := Result = 0;
      pragma Assert
        (Result = 0
          or else Result = ENOMEM
          or else Result = EAGAIN);
   end Create_Task;
 
   ------------------
   -- Finalize_TCB --
   ------------------
 
   procedure Finalize_TCB (T : Task_Id) is
      Result  : Interfaces.C.int;
      Tmp     : Task_Id := T;
      Is_Self : constant Boolean := T = Self;
 
      procedure Free is new
        Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 
   begin
      T.Common.LL.Thread := To_thread_t (0);
 
      if not Single_Lock then
         Result := mutex_destroy (T.Common.LL.L.L'Access);
         pragma Assert (Result = 0);
      end if;
 
      Result := cond_destroy (T.Common.LL.CV'Access);
      pragma Assert (Result = 0);
 
      if T.Known_Tasks_Index /= -1 then
         Known_Tasks (T.Known_Tasks_Index) := null;
      end if;
 
      Free (Tmp);
 
      if Is_Self then
         Specific.Set (null);
      end if;
   end Finalize_TCB;
 
   ---------------
   -- Exit_Task --
   ---------------
 
   --  This procedure must be called with abort deferred. It can no longer
   --  call Self or access the current task's ATCB, since the ATCB has been
   --  deallocated.
 
   procedure Exit_Task is
   begin
      Specific.Set (null);
   end Exit_Task;
 
   ----------------
   -- Abort_Task --
   ----------------
 
   procedure Abort_Task (T : Task_Id) is
      Result : Interfaces.C.int;
   begin
      if Abort_Handler_Installed then
         pragma Assert (T /= Self);
         Result :=
           thr_kill
             (T.Common.LL.Thread,
              Signal (System.Interrupt_Management.Abort_Task_Interrupt));
         pragma Assert (Result = 0);
      end if;
   end Abort_Task;
 
   -----------
   -- Sleep --
   -----------
 
   procedure Sleep
     (Self_ID : Task_Id;
      Reason  : Task_States)
   is
      Result : Interfaces.C.int;
 
   begin
      pragma Assert (Check_Sleep (Reason));
 
      if Single_Lock then
         Result :=
           cond_wait
             (Self_ID.Common.LL.CV'Access, Single_RTS_Lock.L'Access);
      else
         Result :=
           cond_wait
             (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L.L'Access);
      end if;
 
      pragma Assert
        (Record_Wakeup (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Reason));
      pragma Assert (Result = 0 or else Result = EINTR);
   end Sleep;
 
   --  Note that we are relying heavily here on GNAT representing
   --  Calendar.Time, System.Real_Time.Time, Duration,
   --  System.Real_Time.Time_Span in the same way, i.e., as a 64-bit count of
   --  nanoseconds.
 
   --  This allows us to always pass the timeout value as a Duration
 
   --  ???
   --  We are taking liberties here with the semantics of the delays. That is,
   --  we make no distinction between delays on the Calendar clock and delays
   --  on the Real_Time clock. That is technically incorrect, if the Calendar
   --  clock happens to be reset or adjusted. To solve this defect will require
   --  modification to the compiler interface, so that it can pass through more
   --  information, to tell us here which clock to use!
 
   --  cond_timedwait will return if any of the following happens:
   --  1) some other task did cond_signal on this condition variable
   --     In this case, the return value is 0
   --  2) the call just returned, for no good reason
   --     This is called a "spurious wakeup".
   --     In this case, the return value may also be 0.
   --  3) the time delay expires
   --     In this case, the return value is ETIME
   --  4) this task received a signal, which was handled by some
   --     handler procedure, and now the thread is resuming execution
   --     UNIX calls this an "interrupted" system call.
   --     In this case, the return value is EINTR
 
   --  If the cond_timedwait returns 0 or EINTR, it is still possible that the
   --  time has actually expired, and by chance a signal or cond_signal
   --  occurred at around the same time.
 
   --  We have also observed that on some OS's the value ETIME will be
   --  returned, but the clock will show that the full delay has not yet
   --  expired.
 
   --  For these reasons, we need to check the clock after return from
   --  cond_timedwait. If the time has expired, we will set Timedout = True.
 
   --  This check might be omitted for systems on which the cond_timedwait()
   --  never returns early or wakes up spuriously.
 
   --  Annex D requires that completion of a delay cause the task to go to the
   --  end of its priority queue, regardless of whether the task actually was
   --  suspended by the delay. Since cond_timedwait does not do this on
   --  Solaris, we add a call to thr_yield at the end. We might do this at the
   --  beginning, instead, but then the round-robin effect would not be the
   --  same; the delayed task would be ahead of other tasks of the same
   --  priority that awoke while it was sleeping.
 
   --  For Timed_Sleep, we are expecting possible cond_signals to indicate
   --  other events (e.g., completion of a RV or completion of the abortable
   --  part of an async. select), we want to always return if interrupted. The
   --  caller will be responsible for checking the task state to see whether
   --  the wakeup was spurious, and to go back to sleep again in that case. We
   --  don't need to check for pending abort or priority change on the way in
   --  our out; that is the caller's responsibility.
 
   --  For Timed_Delay, we are not expecting any cond_signals or other
   --  interruptions, except for priority changes and aborts. Therefore, we
   --  don't want to return unless the delay has actually expired, or the call
   --  has been aborted. In this case, since we want to implement the entire
   --  delay statement semantics, we do need to check for pending abort and
   --  priority changes. We can quietly handle priority changes inside the
   --  procedure, since there is no entry-queue reordering involved.
 
   -----------------
   -- Timed_Sleep --
   -----------------
 
   procedure Timed_Sleep
     (Self_ID  : Task_Id;
      Time     : Duration;
      Mode     : ST.Delay_Modes;
      Reason   : System.Tasking.Task_States;
      Timedout : out Boolean;
      Yielded  : out Boolean)
   is
      Base_Time  : constant Duration := Monotonic_Clock;
      Check_Time : Duration := Base_Time;
      Abs_Time   : Duration;
      Request    : aliased timespec;
      Result     : Interfaces.C.int;
 
   begin
      pragma Assert (Check_Sleep (Reason));
      Timedout := True;
      Yielded := False;
 
      Abs_Time :=
        (if Mode = Relative
         then Duration'Min (Time, Max_Sensible_Delay) + Check_Time
         else Duration'Min (Check_Time + Max_Sensible_Delay, Time));
 
      if Abs_Time > Check_Time then
         Request := To_Timespec (Abs_Time);
         loop
            exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 
            if Single_Lock then
               Result :=
                 cond_timedwait
                   (Self_ID.Common.LL.CV'Access,
                    Single_RTS_Lock.L'Access, Request'Access);
            else
               Result :=
                 cond_timedwait
                   (Self_ID.Common.LL.CV'Access,
                    Self_ID.Common.LL.L.L'Access, Request'Access);
            end if;
 
            Yielded := True;
 
            Check_Time := Monotonic_Clock;
            exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 
            if Result = 0 or Result = EINTR then
 
               --  Somebody may have called Wakeup for us
 
               Timedout := False;
               exit;
            end if;
 
            pragma Assert (Result = ETIME);
         end loop;
      end if;
 
      pragma Assert
        (Record_Wakeup (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Reason));
   end Timed_Sleep;
 
   -----------------
   -- Timed_Delay --
   -----------------
 
   procedure Timed_Delay
     (Self_ID : Task_Id;
      Time    : Duration;
      Mode    : ST.Delay_Modes)
   is
      Base_Time  : constant Duration := Monotonic_Clock;
      Check_Time : Duration := Base_Time;
      Abs_Time   : Duration;
      Request    : aliased timespec;
      Result     : Interfaces.C.int;
      Yielded    : Boolean := False;
 
   begin
      if Single_Lock then
         Lock_RTS;
      end if;
 
      Write_Lock (Self_ID);
 
      Abs_Time :=
        (if Mode = Relative
         then Time + Check_Time
         else Duration'Min (Check_Time + Max_Sensible_Delay, Time));
 
      if Abs_Time > Check_Time then
         Request := To_Timespec (Abs_Time);
         Self_ID.Common.State := Delay_Sleep;
 
         pragma Assert (Check_Sleep (Delay_Sleep));
 
         loop
            exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 
            if Single_Lock then
               Result :=
                 cond_timedwait
                   (Self_ID.Common.LL.CV'Access,
                    Single_RTS_Lock.L'Access,
                    Request'Access);
            else
               Result :=
                 cond_timedwait
                   (Self_ID.Common.LL.CV'Access,
                    Self_ID.Common.LL.L.L'Access,
                    Request'Access);
            end if;
 
            Yielded := True;
 
            Check_Time := Monotonic_Clock;
            exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 
            pragma Assert
              (Result = 0     or else
               Result = ETIME or else
               Result = EINTR);
         end loop;
 
         pragma Assert
           (Record_Wakeup
              (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Delay_Sleep));
 
         Self_ID.Common.State := Runnable;
      end if;
 
      Unlock (Self_ID);
 
      if Single_Lock then
         Unlock_RTS;
      end if;
 
      if not Yielded then
         thr_yield;
      end if;
   end Timed_Delay;
 
   ------------
   -- Wakeup --
   ------------
 
   procedure Wakeup
     (T : Task_Id;
      Reason : Task_States)
   is
      Result : Interfaces.C.int;
   begin
      pragma Assert (Check_Wakeup (T, Reason));
      Result := cond_signal (T.Common.LL.CV'Access);
      pragma Assert (Result = 0);
   end Wakeup;
 
   ---------------------------
   -- Check_Initialize_Lock --
   ---------------------------
 
   --  The following code is intended to check some of the invariant assertions
   --  related to lock usage, on which we depend.
 
   function Check_Initialize_Lock
     (L     : Lock_Ptr;
      Level : Lock_Level) return Boolean
   is
      Self_ID : constant Task_Id := Self;
 
   begin
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      --  Check that the lock is not yet initialized
 
      if L.Level /= 0 then
         return False;
      end if;
 
      L.Level := Lock_Level'Pos (Level) + 1;
      return True;
   end Check_Initialize_Lock;
 
   ----------------
   -- Check_Lock --
   ----------------
 
   function Check_Lock (L : Lock_Ptr) return Boolean is
      Self_ID : constant Task_Id := Self;
      P       : Lock_Ptr;
 
   begin
      --  Check that the argument is not null
 
      if L = null then
         return False;
      end if;
 
      --  Check that L is not frozen
 
      if L.Frozen then
         return False;
      end if;
 
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      --  Check that caller is not holding this lock already
 
      if L.Owner = To_Owner_ID (To_Address (Self_ID)) then
         return False;
      end if;
 
      if Single_Lock then
         return True;
      end if;
 
      --  Check that TCB lock order rules are satisfied
 
      P := Self_ID.Common.LL.Locks;
      if P /= null then
         if P.Level >= L.Level
           and then (P.Level > 2 or else L.Level > 2)
         then
            return False;
         end if;
      end if;
 
      return True;
   end Check_Lock;
 
   -----------------
   -- Record_Lock --
   -----------------
 
   function Record_Lock (L : Lock_Ptr) return Boolean is
      Self_ID : constant Task_Id := Self;
      P       : Lock_Ptr;
 
   begin
      Lock_Count := Lock_Count + 1;
 
      --  There should be no owner for this lock at this point
 
      if L.Owner /= null then
         return False;
      end if;
 
      --  Record new owner
 
      L.Owner := To_Owner_ID (To_Address (Self_ID));
 
      if Single_Lock then
         return True;
      end if;
 
      --  Check that TCB lock order rules are satisfied
 
      P := Self_ID.Common.LL.Locks;
 
      if P /= null then
         L.Next := P;
      end if;
 
      Self_ID.Common.LL.Locking := null;
      Self_ID.Common.LL.Locks := L;
      return True;
   end Record_Lock;
 
   -----------------
   -- Check_Sleep --
   -----------------
 
   function Check_Sleep (Reason : Task_States) return Boolean is
      pragma Unreferenced (Reason);
 
      Self_ID : constant Task_Id := Self;
      P       : Lock_Ptr;
 
   begin
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      if Single_Lock then
         return True;
      end if;
 
      --  Check that caller is holding own lock, on top of list
 
      if Self_ID.Common.LL.Locks /=
        To_Lock_Ptr (Self_ID.Common.LL.L'Access)
      then
         return False;
      end if;
 
      --  Check that TCB lock order rules are satisfied
 
      if Self_ID.Common.LL.Locks.Next /= null then
         return False;
      end if;
 
      Self_ID.Common.LL.L.Owner := null;
      P := Self_ID.Common.LL.Locks;
      Self_ID.Common.LL.Locks := Self_ID.Common.LL.Locks.Next;
      P.Next := null;
      return True;
   end Check_Sleep;
 
   -------------------
   -- Record_Wakeup --
   -------------------
 
   function Record_Wakeup
     (L      : Lock_Ptr;
      Reason : Task_States) return Boolean
   is
      pragma Unreferenced (Reason);
 
      Self_ID : constant Task_Id := Self;
      P       : Lock_Ptr;
 
   begin
      --  Record new owner
 
      L.Owner := To_Owner_ID (To_Address (Self_ID));
 
      if Single_Lock then
         return True;
      end if;
 
      --  Check that TCB lock order rules are satisfied
 
      P := Self_ID.Common.LL.Locks;
 
      if P /= null then
         L.Next := P;
      end if;
 
      Self_ID.Common.LL.Locking := null;
      Self_ID.Common.LL.Locks := L;
      return True;
   end Record_Wakeup;
 
   ------------------
   -- Check_Wakeup --
   ------------------
 
   function Check_Wakeup
     (T      : Task_Id;
      Reason : Task_States) return Boolean
   is
      Self_ID : constant Task_Id := Self;
 
   begin
      --  Is caller holding T's lock?
 
      if T.Common.LL.L.Owner /= To_Owner_ID (To_Address (Self_ID)) then
         return False;
      end if;
 
      --  Are reasons for wakeup and sleep consistent?
 
      if T.Common.State /= Reason then
         return False;
      end if;
 
      return True;
   end Check_Wakeup;
 
   ------------------
   -- Check_Unlock --
   ------------------
 
   function Check_Unlock (L : Lock_Ptr) return Boolean is
      Self_ID : constant Task_Id := Self;
      P       : Lock_Ptr;
 
   begin
      Unlock_Count := Unlock_Count + 1;
 
      if L = null then
         return False;
      end if;
 
      if L.Buddy /= null then
         return False;
      end if;
 
      --  Magic constant 4???
 
      if L.Level = 4 then
         Check_Count := Unlock_Count;
      end if;
 
      --  Magic constant 1000???
 
      if Unlock_Count - Check_Count > 1000 then
         Check_Count := Unlock_Count;
      end if;
 
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      --  Check that caller is holding this lock, on top of list
 
      if Self_ID.Common.LL.Locks /= L then
         return False;
      end if;
 
      --  Record there is no owner now
 
      L.Owner := null;
      P := Self_ID.Common.LL.Locks;
      Self_ID.Common.LL.Locks := Self_ID.Common.LL.Locks.Next;
      P.Next := null;
      return True;
   end Check_Unlock;
 
   --------------------
   -- Check_Finalize --
   --------------------
 
   function Check_Finalize_Lock (L : Lock_Ptr) return Boolean is
      Self_ID : constant Task_Id := Self;
 
   begin
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      --  Check that no one is holding this lock
 
      if L.Owner /= null then
         return False;
      end if;
 
      L.Frozen := True;
      return True;
   end Check_Finalize_Lock;
 
   ----------------
   -- Initialize --
   ----------------
 
   procedure Initialize (S : in out Suspension_Object) is
      Result : Interfaces.C.int;
 
   begin
      --  Initialize internal state (always to zero (RM D.10(6)))
 
      S.State := False;
      S.Waiting := False;
 
      --  Initialize internal mutex
 
      Result := mutex_init (S.L'Access, USYNC_THREAD, System.Null_Address);
      pragma Assert (Result = 0 or else Result = ENOMEM);
 
      if Result = ENOMEM then
         raise Storage_Error with "Failed to allocate a lock";
      end if;
 
      --  Initialize internal condition variable
 
      Result := cond_init (S.CV'Access, USYNC_THREAD, 0);
      pragma Assert (Result = 0 or else Result = ENOMEM);
 
      if Result /= 0 then
         Result := mutex_destroy (S.L'Access);
         pragma Assert (Result = 0);
 
         if Result = ENOMEM then
            raise Storage_Error;
         end if;
      end if;
   end Initialize;
 
   --------------
   -- Finalize --
   --------------
 
   procedure Finalize (S : in out Suspension_Object) is
      Result  : Interfaces.C.int;
 
   begin
      --  Destroy internal mutex
 
      Result := mutex_destroy (S.L'Access);
      pragma Assert (Result = 0);
 
      --  Destroy internal condition variable
 
      Result := cond_destroy (S.CV'Access);
      pragma Assert (Result = 0);
   end Finalize;
 
   -------------------
   -- Current_State --
   -------------------
 
   function Current_State (S : Suspension_Object) return Boolean is
   begin
      --  We do not want to use lock on this read operation. State is marked
      --  as Atomic so that we ensure that the value retrieved is correct.
 
      return S.State;
   end Current_State;
 
   ---------------
   -- Set_False --
   ---------------
 
   procedure Set_False (S : in out Suspension_Object) is
      Result  : Interfaces.C.int;
 
   begin
      SSL.Abort_Defer.all;
 
      Result := mutex_lock (S.L'Access);
      pragma Assert (Result = 0);
 
      S.State := False;
 
      Result := mutex_unlock (S.L'Access);
      pragma Assert (Result = 0);
 
      SSL.Abort_Undefer.all;
   end Set_False;
 
   --------------
   -- Set_True --
   --------------
 
   procedure Set_True (S : in out Suspension_Object) is
      Result : Interfaces.C.int;
 
   begin
      SSL.Abort_Defer.all;
 
      Result := mutex_lock (S.L'Access);
      pragma Assert (Result = 0);
 
      --  If there is already a task waiting on this suspension object then
      --  we resume it, leaving the state of the suspension object to False,
      --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
      --  the state to True.
 
      if S.Waiting then
         S.Waiting := False;
         S.State := False;
 
         Result := cond_signal (S.CV'Access);
         pragma Assert (Result = 0);
 
      else
         S.State := True;
      end if;
 
      Result := mutex_unlock (S.L'Access);
      pragma Assert (Result = 0);
 
      SSL.Abort_Undefer.all;
   end Set_True;
 
   ------------------------
   -- Suspend_Until_True --
   ------------------------
 
   procedure Suspend_Until_True (S : in out Suspension_Object) is
      Result : Interfaces.C.int;
 
   begin
      SSL.Abort_Defer.all;
 
      Result := mutex_lock (S.L'Access);
      pragma Assert (Result = 0);
 
      if S.Waiting then
 
         --  Program_Error must be raised upon calling Suspend_Until_True
         --  if another task is already waiting on that suspension object
         --  (RM D.10(10)).
 
         Result := mutex_unlock (S.L'Access);
         pragma Assert (Result = 0);
 
         SSL.Abort_Undefer.all;
 
         raise Program_Error;
 
      else
         --  Suspend the task if the state is False. Otherwise, the task
         --  continues its execution, and the state of the suspension object
         --  is set to False (ARM D.10 par. 9).
 
         if S.State then
            S.State := False;
         else
            S.Waiting := True;
 
            loop
               --  Loop in case pthread_cond_wait returns earlier than expected
               --  (e.g. in case of EINTR caused by a signal).
 
               Result := cond_wait (S.CV'Access, S.L'Access);
               pragma Assert (Result = 0 or else Result = EINTR);
 
               exit when not S.Waiting;
            end loop;
         end if;
 
         Result := mutex_unlock (S.L'Access);
         pragma Assert (Result = 0);
 
         SSL.Abort_Undefer.all;
      end if;
   end Suspend_Until_True;
 
   ----------------
   -- Check_Exit --
   ----------------
 
   function Check_Exit (Self_ID : Task_Id) return Boolean is
   begin
      --  Check that caller is just holding Global_Task_Lock and no other locks
 
      if Self_ID.Common.LL.Locks = null then
         return False;
      end if;
 
      --  2 = Global_Task_Level
 
      if Self_ID.Common.LL.Locks.Level /= 2 then
         return False;
      end if;
 
      if Self_ID.Common.LL.Locks.Next /= null then
         return False;
      end if;
 
      --  Check that caller is abort-deferred
 
      if Self_ID.Deferral_Level = 0 then
         return False;
      end if;
 
      return True;
   end Check_Exit;
 
   --------------------
   -- Check_No_Locks --
   --------------------
 
   function Check_No_Locks (Self_ID : Task_Id) return Boolean is
   begin
      return Self_ID.Common.LL.Locks = null;
   end Check_No_Locks;
 
   ----------------------
   -- Environment_Task --
   ----------------------
 
   function Environment_Task return Task_Id is
   begin
      return Environment_Task_Id;
   end Environment_Task;
 
   --------------
   -- Lock_RTS --
   --------------
 
   procedure Lock_RTS is
   begin
      Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
   end Lock_RTS;
 
   ----------------
   -- Unlock_RTS --
   ----------------
 
   procedure Unlock_RTS is
   begin
      Unlock (Single_RTS_Lock'Access, Global_Lock => True);
   end Unlock_RTS;
 
   ------------------
   -- Suspend_Task --
   ------------------
 
   function Suspend_Task
     (T           : ST.Task_Id;
      Thread_Self : Thread_Id) return Boolean
   is
   begin
      if T.Common.LL.Thread /= Thread_Self then
         return thr_suspend (T.Common.LL.Thread) = 0;
      else
         return True;
      end if;
   end Suspend_Task;
 
   -----------------
   -- Resume_Task --
   -----------------
 
   function Resume_Task
     (T           : ST.Task_Id;
      Thread_Self : Thread_Id) return Boolean
   is
   begin
      if T.Common.LL.Thread /= Thread_Self then
         return thr_continue (T.Common.LL.Thread) = 0;
      else
         return True;
      end if;
   end Resume_Task;
 
   --------------------
   -- Stop_All_Tasks --
   --------------------
 
   procedure Stop_All_Tasks is
   begin
      null;
   end Stop_All_Tasks;
 
   ---------------
   -- Stop_Task --
   ---------------
 
   function Stop_Task (T : ST.Task_Id) return Boolean is
      pragma Unreferenced (T);
   begin
      return False;
   end Stop_Task;
 
   -------------------
   -- Continue_Task --
   -------------------
 
   function Continue_Task (T : ST.Task_Id) return Boolean is
      pragma Unreferenced (T);
   begin
      return False;
   end Continue_Task;
 
end System.Task_Primitives.Operations;
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Line No.	Rev	Author	Line
1	281	jeremybenn	`------------------------------------------------------------------------------`
2			`-- --`
3			`-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --`
4			`-- --`
5			`-- S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S --`
6			`-- --`
7			`-- B o d y --`
8			`-- --`
9			`-- Copyright (C) 1992-2009, 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- --`
13			`-- ware Foundation; either version 3, or (at your option) any later ver- --`
14			`-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --`
15			`-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --`
16			`-- or FITNESS FOR A PARTICULAR PURPOSE. --`
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			`-- This is a Solaris (native) version of this package`
33
34			`-- This package contains all the GNULL primitives that interface directly with`
35			`-- the underlying OS.`
36
37			`pragma Polling (Off);`
38			`-- Turn off polling, we do not want ATC polling to take place during tasking`
39			`-- operations. It causes infinite loops and other problems.`
40