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-- --
-- --
-- S Y S T E M . S O F T _ L I N K S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2021, Free Software Foundation, Inc. --
-- --
-- GNAT 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 --
-- --
-- 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 --
-- <>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
-- This package contains a set of subprogram access variables that access
-- some low-level primitives that are different depending whether tasking is
-- involved or not (e.g. the Get/Set_Jmpbuf_Address that needs to provide a
-- different value for each task). To avoid dragging in the tasking runtimes
-- all the time, we use a system of soft links where the links are
-- initialized to non-tasking versions, and then if the tasking support is
-- initialized, they are set to the real tasking versions.
pragma Compiler_Unit_Warning;
with Ada.Exceptions;
with System.Parameters;
with System.Secondary_Stack;
with System.Stack_Checking;
package System.Soft_Links is
pragma Preelaborate;
package SST renames System.Secondary_Stack;
subtype EOA is Ada.Exceptions.Exception_Occurrence_Access;
subtype EO is Ada.Exceptions.Exception_Occurrence;
function Current_Target_Exception return EO;
pragma Import
(Ada, Current_Target_Exception, "__gnat_current_target_exception");
-- Import this subprogram from the private part of Ada.Exceptions
-- First we have the access subprogram types used to establish the links.
-- The approach is to establish variables containing access subprogram
-- values, which by default point to dummy no tasking versions of routines.
type No_Param_Proc is access procedure;
pragma Favor_Top_Level (No_Param_Proc);
pragma Suppress_Initialization (No_Param_Proc);
-- Some uninitialized objects of that type are initialized by the Binder
-- so it is important that such objects are not reset to null during
-- elaboration.
type Addr_Param_Proc is access procedure (Addr : Address);
pragma Favor_Top_Level (Addr_Param_Proc);
type EO_Param_Proc is access procedure (Excep : EO);
pragma Favor_Top_Level (EO_Param_Proc);
type Get_Address_Call is access function return Address;
pragma Favor_Top_Level (Get_Address_Call);
type Set_Address_Call is access procedure (Addr : Address);
pragma Favor_Top_Level (Set_Address_Call);
type Set_Address_Call2 is access procedure
(Self_ID : Address; Addr : Address);
pragma Favor_Top_Level (Set_Address_Call2);
type Get_Integer_Call is access function return Integer;
pragma Favor_Top_Level (Get_Integer_Call);
type Set_Integer_Call is access procedure (Len : Integer);
pragma Favor_Top_Level (Set_Integer_Call);
type Get_EOA_Call is access function return EOA;
pragma Favor_Top_Level (Get_EOA_Call);
type Set_EOA_Call is access procedure (Excep : EOA);
pragma Favor_Top_Level (Set_EOA_Call);
type Set_EO_Call is access procedure (Excep : EO);
pragma Favor_Top_Level (Set_EO_Call);
type Get_Stack_Call is access function return SST.SS_Stack_Ptr;
pragma Favor_Top_Level (Get_Stack_Call);
type Set_Stack_Call is access procedure (Stack : SST.SS_Stack_Ptr);
pragma Favor_Top_Level (Set_Stack_Call);
type Special_EO_Call is access
procedure (Excep : EO := Current_Target_Exception);
pragma Favor_Top_Level (Special_EO_Call);
type Timed_Delay_Call is access
procedure (Time : Duration; Mode : Integer);
pragma Favor_Top_Level (Timed_Delay_Call);
type Get_Stack_Access_Call is access
function return Stack_Checking.Stack_Access;
pragma Favor_Top_Level (Get_Stack_Access_Call);
type Task_Name_Call is access
function return String;
pragma Favor_Top_Level (Task_Name_Call);
-- Suppress checks on all these types, since we know the corresponding
-- values can never be null (the soft links are always initialized).
pragma Suppress (Access_Check, No_Param_Proc);
pragma Suppress (Access_Check, Addr_Param_Proc);
pragma Suppress (Access_Check, EO_Param_Proc);
pragma Suppress (Access_Check, Get_Address_Call);
pragma Suppress (Access_Check, Set_Address_Call);
pragma Suppress (Access_Check, Set_Address_Call2);
pragma Suppress (Access_Check, Get_Integer_Call);
pragma Suppress (Access_Check, Set_Integer_Call);
pragma Suppress (Access_Check, Get_EOA_Call);
pragma Suppress (Access_Check, Set_EOA_Call);
pragma Suppress (Access_Check, Get_Stack_Call);
pragma Suppress (Access_Check, Set_Stack_Call);
pragma Suppress (Access_Check, Timed_Delay_Call);
pragma Suppress (Access_Check, Get_Stack_Access_Call);
pragma Suppress (Access_Check, Task_Name_Call);
-- The following one is not related to tasking/no-tasking but to the
-- traceback decorators for exceptions.
type Traceback_Decorator_Wrapper_Call is access
function (Traceback : System.Address;
Len : Natural)
return String;
pragma Favor_Top_Level (Traceback_Decorator_Wrapper_Call);
-- Declarations for the no tasking versions of the required routines
procedure Abort_Defer_NT;
-- Defer task abort (non-tasking case, does nothing)
procedure Abort_Undefer_NT;
-- Undefer task abort (non-tasking case, does nothing)
procedure Abort_Handler_NT;
-- Handle task abort (non-tasking case, does nothing). Currently, no port
-- makes use of this, but we retain the interface for possible future use.
function Check_Abort_Status_NT return Integer;
-- Returns Boolean'Pos (True) iff abort signal should raise
-- Standard'Abort_Signal.
procedure Task_Lock_NT;
-- Lock out other tasks (non-tasking case, does nothing)
procedure Task_Unlock_NT;
-- Release lock set by Task_Lock (non-tasking case, does nothing)
procedure Task_Termination_NT (Excep : EO);
-- Handle task termination routines for the environment task (non-tasking
-- case, does nothing).
procedure Adafinal_NT;
-- Shuts down the runtime system (non-tasking case)
Abort_Defer : No_Param_Proc := Abort_Defer_NT'Access;
pragma Suppress (Access_Check, Abort_Defer);
-- Defer task abort (task/non-task case as appropriate)
Abort_Undefer : No_Param_Proc := Abort_Undefer_NT'Access;
pragma Suppress (Access_Check, Abort_Undefer);
-- Undefer task abort (task/non-task case as appropriate)
Abort_Handler : No_Param_Proc := Abort_Handler_NT'Access;
-- Handle task abort (task/non-task case as appropriate)
Check_Abort_Status : Get_Integer_Call := Check_Abort_Status_NT'Access;
-- Called when Abort_Signal is delivered to the process. Checks to
-- see if signal should result in raising Standard'Abort_Signal.
Lock_Task : No_Param_Proc := Task_Lock_NT'Access;
-- Locks out other tasks. Preceding a section of code by Task_Lock and
-- following it by Task_Unlock creates a critical region. This is used
-- for ensuring that a region of non-tasking code (such as code used to
-- allocate memory) is tasking safe. Note that it is valid for calls to
-- Task_Lock/Task_Unlock to be nested, and this must work properly, i.e.
-- only the corresponding outer level Task_Unlock will actually unlock.
-- This routine also prevents against asynchronous aborts (abort is
-- deferred).
Unlock_Task : No_Param_Proc := Task_Unlock_NT'Access;
-- Releases lock previously set by call to Lock_Task. In the nested case,
-- all nested locks must be released before other tasks competing for the
-- tasking lock are released.
-- In the non nested case, this routine terminates the protection against
-- asynchronous aborts introduced by Lock_Task (unless abort was already
-- deferred before the call to Lock_Task (e.g in a protected procedures).
-- Note: the recommended protocol for using Lock_Task and Unlock_Task
-- is as follows:
-- Locked_Processing : begin
-- System.Soft_Links.Lock_Task.all;
-- ...
-- System.Soft_Links.Unlock_Task.all;
-- exception
-- when others =>
-- System.Soft_Links.Unlock_Task.all;
-- raise;
-- end Locked_Processing;
-- This ensures that the lock is not left set if an exception is raised
-- explicitly or implicitly during the critical locked region.
Task_Termination_Handler : EO_Param_Proc := Task_Termination_NT'Access;
-- Handle task termination routines (task/non-task case as appropriate)
Finalize_Library_Objects : No_Param_Proc;
pragma Export (C, Finalize_Library_Objects,
-- Will be initialized by the binder
Adafinal : No_Param_Proc := Adafinal_NT'Access;
-- Performs the finalization of the Ada Runtime
function Get_Jmpbuf_Address_NT return Address;
procedure Set_Jmpbuf_Address_NT (Addr : Address);
Get_Jmpbuf_Address : Get_Address_Call := Get_Jmpbuf_Address_NT'Access;
Set_Jmpbuf_Address : Set_Address_Call := Set_Jmpbuf_Address_NT'Access;
function Get_Sec_Stack_NT return SST.SS_Stack_Ptr;
procedure Set_Sec_Stack_NT (Stack : SST.SS_Stack_Ptr);
Get_Sec_Stack : Get_Stack_Call := Get_Sec_Stack_NT'Access;
Set_Sec_Stack : Set_Stack_Call := Set_Sec_Stack_NT'Access;
function Get_Current_Excep_NT return EOA;
Get_Current_Excep : Get_EOA_Call := Get_Current_Excep_NT'Access;
function Get_Stack_Info_NT return Stack_Checking.Stack_Access;
Get_Stack_Info : Get_Stack_Access_Call := Get_Stack_Info_NT'Access;
-- Master_Id Soft-Links --
-- Soft-Links are used for procedures that manipulate Master_Ids because
-- a Master_Id must be generated for access to limited class-wide types,
-- whose root may be extended with task components.
function Current_Master_NT return Integer;
procedure Enter_Master_NT;
procedure Complete_Master_NT;
Current_Master : Get_Integer_Call := Current_Master_NT'Access;
Enter_Master : No_Param_Proc := Enter_Master_NT'Access;
Complete_Master : No_Param_Proc := Complete_Master_NT'Access;
-- Delay Soft-Links --
-- Soft-Links are used for procedures that manipulate time to avoid
-- dragging the tasking run time when using delay statements.
Timed_Delay : Timed_Delay_Call;
-- Task Name Soft-Links --
function Task_Name_NT return String;
Task_Name : Task_Name_Call := Task_Name_NT'Access;
-- Exception Tracebacks Soft-Links --
Library_Exception : EO;
-- Library-level finalization routines use this common reference to store
-- the first library-level exception which occurs during finalization.
Library_Exception_Set : Boolean := False;
-- Used in conjunction with Library_Exception, set when an exception has
-- been stored.
Traceback_Decorator_Wrapper : Traceback_Decorator_Wrapper_Call;
-- Wrapper to the possible user specified traceback decorator to be
-- called during automatic output of exception data.
-- The null value of this wrapper corresponds to the null value of the
-- current actual decorator. This is ensured first by the null initial
-- value of the corresponding variables, and then by Set_Trace_Decorator
-- in g-exctra.adb.
pragma Atomic (Traceback_Decorator_Wrapper);
-- Since concurrent read/write operations may occur on this variable.
-- See the body of Tailored_Exception_Traceback in
-- Ada.Exceptions.Exception_Data for a more detailed description of the
-- potential problems.
procedure Save_Library_Occurrence (E : EOA);
-- When invoked, this routine saves an exception occurrence into a hidden
-- reference. Subsequent calls will have no effect.
-- Task Specific Data --
-- Here we define a single type that encapsulates the various task
-- specific data. This type is used to store the necessary data into the
-- Task_Control_Block or into a global variable in the non tasking case.
type TSD is record
Pri_Stack_Info : aliased Stack_Checking.Stack_Info;
-- Information on stack (Base/Limit/Size) used by System.Stack_Checking.
-- If this TSD does not belong to the environment task, the Size field
-- must be initialized to the tasks requested stack size before the task
-- can do its first stack check.
Jmpbuf_Address : System.Address;
-- Address of jump buffer used to store the address of the current
-- longjmp/setjmp buffer for exception management. These buffers are
-- threaded into a stack, and the address here is the top of the stack.
-- A null address means that no exception handler is currently active.
Sec_Stack_Ptr : SST.SS_Stack_Ptr;
-- Pointer of the allocated secondary stack
Current_Excep : aliased EO;
-- Exception occurrence that contains the information for the current
-- exception. Note that any exception in the same task destroys this
-- information, so the data in this variable must be copied out before
-- another exception can occur.
-- Also act as a list of the active exceptions in the case of the GCC
-- exception mechanism, organized as a stack with the most recent first.
end record;
procedure Create_TSD
(New_TSD : in out TSD;
Sec_Stack : SST.SS_Stack_Ptr;
Sec_Stack_Size : System.Parameters.Size_Type);
pragma Inline (Create_TSD);
-- Called from s-tassta when a new thread is created to perform
-- any required initialization of the TSD.
procedure Destroy_TSD (Old_TSD : in out TSD);
pragma Inline (Destroy_TSD);
-- Called from s-tassta just before a thread is destroyed to perform
-- any required finalization.
function Get_GNAT_Exception return Ada.Exceptions.Exception_Id;
pragma Inline (Get_GNAT_Exception);
-- This function obtains the Exception_Id from the Exception_Occurrence
-- referenced by the Current_Excep field of the task specific data, i.e.
-- the call is equivalent to
-- Exception_Identity (Get_Current_Exception.all)
-- Export the Get/Set routines for the various Task Specific Data (TSD)
-- elements as callable subprograms instead of objects of access to
-- subprogram types.
function Get_Jmpbuf_Address_Soft return Address;
procedure Set_Jmpbuf_Address_Soft (Addr : Address);
pragma Inline (Get_Jmpbuf_Address_Soft);
pragma Inline (Set_Jmpbuf_Address_Soft);
function Get_Sec_Stack_Soft return SST.SS_Stack_Ptr;
procedure Set_Sec_Stack_Soft (Stack : SST.SS_Stack_Ptr);
pragma Inline (Get_Sec_Stack_Soft);
pragma Inline (Set_Sec_Stack_Soft);
-- The following is a dummy record designed to mimic Communication_Block as
-- defined in
-- type Communication_Block is record
-- Self : Task_Id; -- An access type
-- Enqueued : Boolean := True;
-- Cancelled : Boolean := False;
-- end record;
-- The record is used in the construction of the predefined dispatching
-- primitive _disp_asynchronous_select in order to avoid the import of
-- System.Tasking.Protected_Objects.Operations. Note that this package
-- is always imported in the presence of interfaces since the dispatch
-- table uses entities from here.
type Dummy_Communication_Block is record
Comp_1 : Address; -- Address and access have the same size
Comp_2 : Boolean;
Comp_3 : Boolean;
end record;
-- The task specific data for the main task when the Ada tasking run-time
-- is not used. It relies on the default initialization of NT_TSD. It is
-- placed here and not the body to ensure the default initialization does
-- not clobber the secondary stack initialization that occurs as part of
-- System.Soft_Links.Initialization.
end System.Soft_Links;