------------------------------------------------------------------------------
-- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
+-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . S T A C K _ C H E C K I N G --
-- --
-- B o d y --
-- --
--- --
--- Copyright (C) 1999-2001 Free Software Foundation, Inc. --
+-- Copyright (C) 1999-2009, 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 2, or (at your option) any later ver- --
--- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
+-- 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. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNARL; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- 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. --
-- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- 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. It is --
--- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
--- State University (http://www.gnat.com). --
+-- GNARL was developed by the GNARL team at Florida State University. --
+-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-with Ada.Exceptions;
+pragma Compiler_Unit;
-with System.Storage_Elements; use System.Storage_Elements;
-with System.Parameters; use System.Parameters;
-with System.Soft_Links;
+-- As noted in the spec, this dummy body is present because otherwise we
+-- have bootstrapping path problems (there used to be a real body).
package body System.Stack_Checking is
-
- Kilobyte : constant Storage_Offset := 1024;
- Default_Env_Stack_Size : constant Storage_Offset := 8000 * Kilobyte;
- -- This size is assumed for the environment stack when no size has been
- -- set by the runtime, and no GNAT_STACK_LIMIT environment variable was
- -- present. The value is chosen to be just under 8 MB whic is the actual
- -- default size on some systems including GNU/LinuxThreads, so we will get
- -- correct storage errors on those systems without setting environment
- -- variables.
-
- function Set_Stack_Info (Stack : access Stack_Access) return Stack_Access;
-
- -- The function Set_Stack_Info is the actual function that updates
- -- the cache containing a pointer to the Stack_Info. It may also
- -- be used for detecting asynchronous abort in combination with
- -- Invalidate_Self_Cache.
-
- -- Set_Stack_Info should do the following things in order:
- -- 1) Get the Stack_Access value for the current task
- -- 2) Set Stack.all to the value obtained in 1)
- -- 3) Optionally Poll to check for asynchronous abort
-
- -- This order is important because if at any time a write to
- -- the stack cache is pending, that write should be followed
- -- by a Poll to prevent loosing signals.
-
- -- Note: This function must be compiled with Polling turned off
-
- -- Note: on systems like VxWorks and OS/2 with real thread-local storage,
- -- Set_Stack_Info should return an access value for such local
- -- storage. In those cases the cache will always be up-to-date.
-
- -- The following constants should be imported from some system-specific
- -- constants package. The constants must be static for performance reasons.
-
- ----------------------------
- -- Invalidate_Stack_Cache --
- ----------------------------
-
- procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access) is
- pragma Warnings (Off, Any_Stack);
-
- begin
- Cache := Null_Stack;
- end Invalidate_Stack_Cache;
-
- --------------------
- -- Set_Stack_Info --
- --------------------
-
- function Set_Stack_Info
- (Stack : access Stack_Access)
- return Stack_Access
- is
- type Frame_Mark is null record;
- Frame_Location : Frame_Mark;
- Frame_Address : Address := Frame_Location'Address;
-
- My_Stack : Stack_Access;
- Limit_Chars : System.Address;
- Limit : Integer;
-
- function getenv (S : String) return System.Address;
- pragma Import (C, getenv, External_Name => "getenv");
-
- function atoi (A : System.Address) return Integer;
- pragma Import (C, atoi);
-
- begin
- -- The order of steps 1 .. 3 is important, see specification.
-
- -- 1) Get the Stack_Access value for the current task
-
- My_Stack := Soft_Links.Get_Stack_Info.all;
-
- if My_Stack.Base = Null_Address then
-
- -- First invocation, initialize based on the assumption that
- -- there are Environment_Stack_Size bytes available beyond
- -- the current frame address.
-
- if My_Stack.Size = 0 then
-
- My_Stack.Size := Default_Env_Stack_Size;
-
- -- When the environment variable GNAT_STACK_LIMIT is set,
- -- set Environment_Stack_Size to that number of kB.
-
- Limit_Chars := getenv ("GNAT_STACK_LIMIT" & ASCII.NUL);
-
- if Limit_Chars /= Null_Address then
- Limit := atoi (Limit_Chars);
- if Limit >= 0 then
- My_Stack.Size := Storage_Offset (Limit) * Kilobyte;
- end if;
- end if;
- end if;
-
- My_Stack.Base := Frame_Address;
-
- if Stack_Grows_Down then
-
- -- Prevent wrap-around on too big stack sizes
-
- My_Stack.Limit := My_Stack.Base - My_Stack.Size;
-
- if My_Stack.Limit > My_Stack.Base then
- My_Stack.Limit := Address'First;
- end if;
-
- else
- My_Stack.Limit := My_Stack.Base + My_Stack.Size;
-
- -- Prevent wrap-around on too big stack sizes
-
- if My_Stack.Limit < My_Stack.Base then
- My_Stack.Limit := Address'Last;
- end if;
- end if;
- end if;
-
- -- 2) Set Stack.all to the value obtained in 1)
-
- Stack.all := My_Stack;
-
- -- 3) Optionally Poll to check for asynchronous abort
-
- if Soft_Links.Check_Abort_Status.all /= 0 then
- raise Standard'Abort_Signal;
- end if;
-
- return My_Stack; -- Never trust the cached value, but return local copy!
- end Set_Stack_Info;
-
- --------------------
- -- Set_Stack_Size --
- --------------------
-
- -- Specify the stack size for the current frame.
-
- procedure Set_Stack_Size
- (Stack_Size : System.Storage_Elements.Storage_Offset)
- is
- My_Stack : Stack_Access;
- Frame_Address : constant System.Address := My_Stack'Address;
-
- begin
- My_Stack := Stack_Check (Frame_Address);
-
- if Stack_Grows_Down then
- My_Stack.Limit := My_Stack.Base - Stack_Size;
- else
- My_Stack.Limit := My_Stack.Base + Stack_Size;
- end if;
- end Set_Stack_Size;
-
- -----------------
- -- Stack_Check --
- -----------------
-
- function Stack_Check
- (Stack_Address : System.Address)
- return Stack_Access
- is
- type Frame_Marker is null record;
- Marker : Frame_Marker;
- Cached_Stack : constant Stack_Access := Cache;
- Frame_Address : constant System.Address := Marker'Address;
-
- begin
- -- This function first does a "cheap" check which is correct
- -- if it succeeds. In case of failure, the full check is done.
- -- Ideally the cheap check should be done in an optimized manner,
- -- or be inlined.
-
- if (Stack_Grows_Down and then
- (Frame_Address <= Cached_Stack.Base
- and
- Stack_Address > Cached_Stack.Limit))
- or else
- (not Stack_Grows_Down and then
- (Frame_Address >= Cached_Stack.Base
- and
- Stack_Address < Cached_Stack.Limit))
- then
- -- Cached_Stack is valid as it passed the stack check
- return Cached_Stack;
- end if;
-
- Full_Check :
- declare
- My_Stack : Stack_Access := Set_Stack_Info (Cache'Access);
- -- At this point Stack.all might already be invalid, so
- -- it is essential to use our local copy of Stack!
-
- begin
-
- if (Stack_Grows_Down and then
- (not (Frame_Address <= My_Stack.Base)))
- or else
- (not Stack_Grows_Down and then
- (not (Frame_Address >= My_Stack.Base)))
- then
- -- The returned Base is lower than the stored one,
- -- so assume that the original one wasn't right and use the
- -- current Frame_Address as new one. This allows initializing
- -- Base with the Frame_Address as approximation.
- -- During initialization the Frame_Address will be close to
- -- the stack base anyway: the difference should be compensated
- -- for in the stack reserve.
-
- My_Stack.Base := Frame_Address;
- end if;
-
- if (Stack_Grows_Down and then
- Stack_Address < My_Stack.Limit)
- or else
- (not Stack_Grows_Down and then
- Stack_Address > My_Stack.Limit)
- then
- Ada.Exceptions.Raise_Exception
- (E => Storage_Error'Identity,
- Message => "stack overflow detected");
- end if;
-
- return My_Stack;
- end Full_Check;
- end Stack_Check;
-
- ------------------------
- -- Update_Stack_Cache --
- ------------------------
-
- procedure Update_Stack_Cache (Stack : Stack_Access) is
- begin
- if not Multi_Processor then
- Cache := Stack;
- end if;
- end Update_Stack_Cache;
-
end System.Stack_Checking;
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