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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                       ADA.EXCEPTIONS.EXCEPTION_DATA                      --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1992-2011, 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 --

-- 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/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with System.Storage_Elements; use System.Storage_Elements;

separate (Ada.Exceptions)

package body Exception_Data is

   --  This unit implements the Exception_Information related services for

   --  both the Ada standard requirements and the GNAT.Exception_Traces

   --  facility.

   --  There are common parts between the contents of Exception_Information

   --  (the regular Ada interface) and Tailored_Exception_Information (what

   --  the automatic backtracing output includes). The overall structure is

   --  sketched below:

   --

   --                      Exception_Information

   --                               |

   --                       +-------+--------+

   --                       |                |

   --                Basic_Exc_Info & Basic_Exc_Tback

   --                    (B_E_I)          (B_E_TB)

   --           o--

   --  (B_E_I)  |  Exception_Name: <exception name> (as in Exception_Name)

   --           |  Message: <message> (or a null line if no message)

   --           |  PID=nnnn (if != 0)

   --           o--

   --  (B_E_TB) |  Call stack traceback locations:

   --           |  <0xyyyyyyyy 0xyyyyyyyy ...>

   --           o--

   --                  Tailored_Exception_Information

   --                               |

   --                    +----------+----------+

   --                    |                     |

   --             Basic_Exc_Info    &  Tailored_Exc_Tback

   --                                          |

   --                              +-----------+------------+

   --                              |                        |

   --                       Basic_Exc_Tback    Or    Tback_Decorator

   --                     if no decorator set           otherwise

   --  Functions returning String imply secondary stack use, which is a heavy

   --  mechanism requiring run-time support. Besides, some of the routines we

   --  provide here are to be used by the default Last_Chance_Handler, at the

   --  critical point where the runtime is about to be finalized. Since most

   --  of the items we have at hand are of bounded length, we also provide a

   --  procedural interface able to incrementally append the necessary bits to

   --  a preallocated buffer or output them straight to stderr.

   --  The procedural interface is composed of two major sections: a neutral

   --  section for basic types like Address, Character, Natural or String, and

   --  an exception oriented section for the e.g. Basic_Exception_Information.

   --  This is the Append_Info family of procedures below.

   --  Output to stderr is commanded by passing an empty buffer to update, and

   --  care is taken not to overflow otherwise.

   --------------------------------------------

   -- Procedural Interface - Neutral section --

   --------------------------------------------

   procedure Append_Info_Address

     (A    : Address;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Character

     (C    : Character;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Nat

     (N    : Natural;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_NL

     (Info : in out String;

      Ptr  : in out Natural);

   pragma Inline (Append_Info_NL);

   procedure Append_Info_String

     (S    : String;

      Info : in out String;

      Ptr  : in out Natural);

   -------------------------------------------------------

   -- Procedural Interface - Exception oriented section --

   -------------------------------------------------------

   procedure Append_Info_Exception_Name

     (Id   : Exception_Id;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Exception_Name

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Exception_Message

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Basic_Exception_Information

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Basic_Exception_Traceback

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural);

   procedure Append_Info_Exception_Information

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural);

   --  The "functional" interface to the exception information not involving

   --  a traceback decorator uses preallocated intermediate buffers to avoid

   --  the use of secondary stack. Preallocation requires preliminary length

   --  computation, for which a series of functions are introduced:

   ---------------------------------

   -- Length evaluation utilities --

   ---------------------------------

   function Basic_Exception_Info_Maxlength

     (X : Exception_Occurrence) return Natural;

   function Basic_Exception_Tback_Maxlength

     (X : Exception_Occurrence) return Natural;

   function Exception_Info_Maxlength

     (X : Exception_Occurrence) return Natural;

   function Exception_Name_Length

     (Id : Exception_Id) return Natural;

   function Exception_Name_Length

     (X : Exception_Occurrence) return Natural;

   function Exception_Message_Length

     (X : Exception_Occurrence) return Natural;

   --------------------------

   -- Functional Interface --

   --------------------------

   function Basic_Exception_Traceback

     (X : Exception_Occurrence) return String;

   --  Returns an image of the complete call chain associated with an

   --  exception occurrence in its most basic form, that is as a raw sequence

   --  of hexadecimal binary addresses.

   function Tailored_Exception_Traceback

     (X : Exception_Occurrence) return String;

   --  Returns an image of the complete call chain associated with an

   --  exception occurrence, either in its basic form if no decorator is

   --  in place, or as formatted by the decorator otherwise.

   -----------------------------------------------------------------------

   -- Services for the default Last_Chance_Handler and the task wrapper --

   -----------------------------------------------------------------------

   pragma Export

     (Ada, Append_Info_Exception_Message, "__gnat_append_info_e_msg");

   pragma Export

     (Ada, Append_Info_Exception_Information, "__gnat_append_info_e_info");

   pragma Export

     (Ada, Exception_Message_Length, "__gnat_exception_msg_len");

   -------------------------

   -- Append_Info_Address --

   -------------------------

   procedure Append_Info_Address

     (A    : Address;

      Info : in out String;

      Ptr  : in out Natural)

   is

      S : String (1 .. 18);

      P : Natural;

      N : Integer_Address;

      H : constant array (Integer range 0 .. 15) of Character :=

                                                         "0123456789abcdef";

   begin

      P := S'Last;

      N := To_Integer (A);

      loop

         S (P) := H (Integer (N mod 16));

         P := P - 1;

         N := N / 16;

         exit when N = 0;

      end loop;

      S (P - 1) := '0';

      S (P) := 'x';

      Append_Info_String (S (P - 1 .. S'Last), Info, Ptr);

   end Append_Info_Address;

   ---------------------------

   -- Append_Info_Character --

   ---------------------------

   procedure Append_Info_Character

     (C    : Character;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if Info'Length = 0 then

         To_Stderr (C);

      elsif Ptr < Info'Last then

         Ptr := Ptr + 1;

         Info (Ptr) := C;

      end if;

   end Append_Info_Character;

   ---------------------

   -- Append_Info_Nat --

   ---------------------

   procedure Append_Info_Nat

     (N    : Natural;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if N > 9 then

         Append_Info_Nat (N / 10, Info, Ptr);

      end if;

      Append_Info_Character

        (Character'Val (Character'Pos ('0') + N mod 10), Info, Ptr);

   end Append_Info_Nat;

   --------------------

   -- Append_Info_NL --

   --------------------

   procedure Append_Info_NL

     (Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      Append_Info_Character (ASCII.LF, Info, Ptr);

   end Append_Info_NL;

   ------------------------

   -- Append_Info_String --

   ------------------------

   procedure Append_Info_String

     (S    : String;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if Info'Length = 0 then

         To_Stderr (S);

      else

         declare

            Last : constant Natural :=

              Integer'Min (Ptr + S'Length, Info'Last);

         begin

            Info (Ptr + 1 .. Last) := S;

            Ptr := Last;

         end;

      end if;

   end Append_Info_String;

   ---------------------------------------------

   -- Append_Info_Basic_Exception_Information --

   ---------------------------------------------

   --  To ease the maximum length computation, we define and pull out a couple

   --  of string constants:

   BEI_Name_Header : constant String := "Exception name: ";

   BEI_Msg_Header  : constant String := "Message: ";

   BEI_PID_Header  : constant String := "PID: ";

   procedure Append_Info_Basic_Exception_Information

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural)

   is

      Name : String (1 .. Exception_Name_Length (X));

      --  Buffer in which to fetch the exception name, in order to check

      --  whether this is an internal _ABORT_SIGNAL or a regular occurrence.

      Name_Ptr : Natural := Name'First - 1;

   begin

      --  Output exception name and message except for _ABORT_SIGNAL, where

      --  these two lines are omitted.

      Append_Info_Exception_Name (X, Name, Name_Ptr);

      if Name (Name'First) /= '_' then

         Append_Info_String (BEI_Name_Header, Info, Ptr);

         Append_Info_String (Name, Info, Ptr);

         Append_Info_NL (Info, Ptr);

         if Exception_Message_Length (X) /= 0 then

            Append_Info_String (BEI_Msg_Header, Info, Ptr);

            Append_Info_Exception_Message  (X, Info, Ptr);

            Append_Info_NL (Info, Ptr);

         end if;

      end if;

      --  Output PID line if non-zero

      if X.Pid /= 0 then

         Append_Info_String (BEI_PID_Header, Info, Ptr);

         Append_Info_Nat (X.Pid, Info, Ptr);

         Append_Info_NL (Info, Ptr);

      end if;

   end Append_Info_Basic_Exception_Information;

   -------------------------------------------

   -- Basic_Exception_Information_Maxlength --

   -------------------------------------------

   function Basic_Exception_Info_Maxlength

     (X : Exception_Occurrence) return Natural is

   begin

      return

        BEI_Name_Header'Length + Exception_Name_Length (X) + 1

        + BEI_Msg_Header'Length + Exception_Message_Length (X) + 1

        + BEI_PID_Header'Length + 15;

   end Basic_Exception_Info_Maxlength;

   -------------------------------------------

   -- Append_Info_Basic_Exception_Traceback --

   -------------------------------------------

   --  As for Basic_Exception_Information:

   BETB_Header : constant String := "Call stack traceback locations:";

   procedure Append_Info_Basic_Exception_Traceback

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if X.Num_Tracebacks = 0 then

         return;

      end if;

      Append_Info_String (BETB_Header, Info, Ptr);

      Append_Info_NL (Info, Ptr);

      for J in 1 .. X.Num_Tracebacks loop

         Append_Info_Address (TBE.PC_For (X.Tracebacks (J)), Info, Ptr);

         exit when J = X.Num_Tracebacks;

         Append_Info_Character (' ', Info, Ptr);

      end loop;

      Append_Info_NL (Info, Ptr);

   end Append_Info_Basic_Exception_Traceback;

   -----------------------------------------

   -- Basic_Exception_Traceback_Maxlength --

   -----------------------------------------

   function Basic_Exception_Tback_Maxlength

     (X : Exception_Occurrence) return Natural

   is

      Space_Per_Traceback : constant := 2 + 16 + 1;

      --  Space for "0x" + HHHHHHHHHHHHHHHH + " "

   begin

      return BETB_Header'Length + 1 +

               X.Num_Tracebacks * Space_Per_Traceback + 1;

   end Basic_Exception_Tback_Maxlength;

   ---------------------------------------

   -- Append_Info_Exception_Information --

   ---------------------------------------

   procedure Append_Info_Exception_Information

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      Append_Info_Basic_Exception_Information (X, Info, Ptr);

      Append_Info_Basic_Exception_Traceback   (X, Info, Ptr);

   end Append_Info_Exception_Information;

   ------------------------------

   -- Exception_Info_Maxlength --

   ------------------------------

   function Exception_Info_Maxlength

     (X : Exception_Occurrence) return Natural

   is

   begin

      return

        Basic_Exception_Info_Maxlength (X)

        + Basic_Exception_Tback_Maxlength (X);

   end Exception_Info_Maxlength;

   -----------------------------------

   -- Append_Info_Exception_Message --

   -----------------------------------

   procedure Append_Info_Exception_Message

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if X.Id = Null_Id then

         raise Constraint_Error;

      end if;

      declare

         Len : constant Natural           := Exception_Message_Length (X);

         Msg : constant String (1 .. Len) := X.Msg (1 .. Len);

      begin

         Append_Info_String (Msg, Info, Ptr);

      end;

   end Append_Info_Exception_Message;

   --------------------------------

   -- Append_Info_Exception_Name --

   --------------------------------

   procedure Append_Info_Exception_Name

     (Id   : Exception_Id;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      if Id = Null_Id then

         raise Constraint_Error;

      end if;

      declare

         Len  : constant Natural           := Exception_Name_Length (Id);

         Name : constant String (1 .. Len) := To_Ptr (Id.Full_Name) (1 .. Len);

      begin

         Append_Info_String (Name, Info, Ptr);

      end;

   end Append_Info_Exception_Name;

   procedure Append_Info_Exception_Name

     (X    : Exception_Occurrence;

      Info : in out String;

      Ptr  : in out Natural)

   is

   begin

      Append_Info_Exception_Name (X.Id, Info, Ptr);

   end Append_Info_Exception_Name;

   ---------------------------

   -- Exception_Name_Length --

   ---------------------------

   function Exception_Name_Length

     (Id : Exception_Id) return Natural

   is

   begin

      --  What is stored in the internal Name buffer includes a terminating

      --  null character that we never care about.

      return Id.Name_Length - 1;

   end Exception_Name_Length;

   function Exception_Name_Length

     (X : Exception_Occurrence) return Natural is

   begin

      return Exception_Name_Length (X.Id);

   end Exception_Name_Length;

   ------------------------------

   -- Exception_Message_Length --

   ------------------------------

   function Exception_Message_Length

     (X : Exception_Occurrence) return Natural

   is

   begin

      return X.Msg_Length;

   end Exception_Message_Length;

   -------------------------------

   -- Basic_Exception_Traceback --

   -------------------------------

   function Basic_Exception_Traceback

     (X : Exception_Occurrence) return String

   is

      Info : aliased String (1 .. Basic_Exception_Tback_Maxlength (X));

      Ptr  : Natural := Info'First - 1;

   begin

      Append_Info_Basic_Exception_Traceback (X, Info, Ptr);

      return Info (Info'First .. Ptr);

   end Basic_Exception_Traceback;

   ---------------------------

   -- Exception_Information --

   ---------------------------

   function Exception_Information

     (X : Exception_Occurrence) return String

   is

      Info : String (1 .. Exception_Info_Maxlength (X));

      Ptr  : Natural := Info'First - 1;

   begin

      Append_Info_Exception_Information (X, Info, Ptr);

      return Info (Info'First .. Ptr);

   end Exception_Information;

   -------------------------

   -- Set_Exception_C_Msg --

   -------------------------

   procedure Set_Exception_C_Msg

     (Id     : Exception_Id;

      Msg1   : System.Address;

      Line   : Integer        := 0;

      Column : Integer        := 0;

      Msg2   : System.Address := System.Null_Address)

   is

      Excep  : constant EOA := Get_Current_Excep.all;

      Remind : Integer;

      Ptr    : Natural;

      procedure Append_Number (Number : Integer);

      --  Append given number to Excep.Msg

      -------------------

      -- Append_Number --

      -------------------

      procedure Append_Number (Number : Integer) is

         Val  : Integer;

         Size : Integer;

      begin

         if Number <= 0 then

            return;

         end if;

         --  Compute the number of needed characters

         Size := 1;

         Val := Number;

         while Val > 0 loop

            Val := Val / 10;

            Size := Size + 1;

         end loop;

         --  If enough characters are available, put the line number

         if Excep.Msg_Length <= Exception_Msg_Max_Length - Size then

            Excep.Msg (Excep.Msg_Length + 1) := ':';

            Excep.Msg_Length := Excep.Msg_Length + Size;

            Val := Number;

            Size := 0;

            while Val > 0 loop

               Remind := Val rem 10;

               Val := Val / 10;

               Excep.Msg (Excep.Msg_Length - Size) :=

                 Character'Val (Remind + Character'Pos ('0'));

               Size := Size + 1;

            end loop;

         end if;

      end Append_Number;

   --  Start of processing for Set_Exception_C_Msg

   begin

      Excep.Exception_Raised := False;

      Excep.Id               := Id;

      Excep.Num_Tracebacks   := 0;

      Excep.Pid              := Local_Partition_ID;

      Excep.Msg_Length       := 0;

      while To_Ptr (Msg1) (Excep.Msg_Length + 1) /= ASCII.NUL

        and then Excep.Msg_Length < Exception_Msg_Max_Length

      loop

         Excep.Msg_Length := Excep.Msg_Length + 1;

         Excep.Msg (Excep.Msg_Length) := To_Ptr (Msg1) (Excep.Msg_Length);

      end loop;

      Append_Number (Line);

      Append_Number (Column);

      --  Append second message if present

      if Msg2 /= System.Null_Address

        and then Excep.Msg_Length + 1 < Exception_Msg_Max_Length

      then

         Excep.Msg_Length := Excep.Msg_Length + 1;

         Excep.Msg (Excep.Msg_Length) := ' ';

         Ptr := 1;

         while To_Ptr (Msg2) (Ptr) /= ASCII.NUL

           and then Excep.Msg_Length < Exception_Msg_Max_Length

         loop

            Excep.Msg_Length := Excep.Msg_Length + 1;

            Excep.Msg (Excep.Msg_Length) := To_Ptr (Msg2) (Ptr);

            Ptr := Ptr + 1;

         end loop;

      end if;

   end Set_Exception_C_Msg;

   -----------------------

   -- Set_Exception_Msg --

   -----------------------

   procedure Set_Exception_Msg

     (Id      : Exception_Id;

      Message : String)

   is

      Len   : constant Natural :=

                Natural'Min (Message'Length, Exception_Msg_Max_Length);

      First : constant Integer := Message'First;

      Excep : constant EOA     := Get_Current_Excep.all;

   begin

      Excep.Exception_Raised := False;

      Excep.Msg_Length       := Len;

      Excep.Msg (1 .. Len)   := Message (First .. First + Len - 1);

      Excep.Id               := Id;

      Excep.Num_Tracebacks   := 0;

      Excep.Pid              := Local_Partition_ID;

   end Set_Exception_Msg;

   ----------------------------------

   -- Tailored_Exception_Traceback --

   ----------------------------------

   function Tailored_Exception_Traceback

     (X : Exception_Occurrence) return String

   is

      --  We reference the decorator *wrapper* here and not the decorator

      --  itself. The purpose of the local variable Wrapper is to prevent a

      --  potential race condition in the code below. The atomicity of this

      --  assignment is enforced by pragma Atomic in System.Soft_Links.

      --  The potential race condition here, if no local variable was used,

      --  relates to the test upon the wrapper's value and the call, which

      --  are not performed atomically. With the local variable, potential

      --  changes of the wrapper's global value between the test and the

      --  call become inoffensive.

      Wrapper : constant Traceback_Decorator_Wrapper_Call :=

                  Traceback_Decorator_Wrapper;

   begin

      if Wrapper = null then

         return Basic_Exception_Traceback (X);

      else

         return Wrapper.all (X.Tracebacks'Address, X.Num_Tracebacks);

      end if;

   end Tailored_Exception_Traceback;

   ------------------------------------

   -- Tailored_Exception_Information --

   ------------------------------------

   function Tailored_Exception_Information

     (X : Exception_Occurrence) return String

   is

      --  The tailored exception information is the basic information

      --  associated with the tailored call chain backtrace.

      Tback_Info : constant String  := Tailored_Exception_Traceback (X);

      Tback_Len  : constant Natural := Tback_Info'Length;

      Info : String (1 .. Basic_Exception_Info_Maxlength (X) + Tback_Len);

      Ptr  : Natural := Info'First - 1;

   begin

      Append_Info_Basic_Exception_Information (X, Info, Ptr);

      Append_Info_String (Tback_Info, Info, Ptr);

      return Info (Info'First .. Ptr);

   end Tailored_Exception_Information;

end Exception_Data;