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+------------------------------------------------------------------------------
+-- --
+-- GNAT RUN-TIME COMPONENTS --
+-- --
+-- A D A . E X C E P T I O N S --
+-- --
+-- S p e c --
+-- --
+-- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
+-- --
+-- This specification is derived from the Ada Reference Manual for use with --
+-- GNAT. The copyright notice above, and the license provisions that follow --
+-- apply solely to the contents of the part following the private keyword. --
+-- --
+-- 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 2, 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 GNAT; see file COPYING. If not, write --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
+-- --
+-- 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. --
+-- --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
+-- --
+------------------------------------------------------------------------------
+
+-- This version of Ada.Exceptions is a full Ada 95 version, but lacks the
+-- additional definitions of Exception_Name returning Wide_[Wide_]String.
+-- It is used for building the compiler and the basic tools, since these
+-- builds may be done with bootstrap compilers that cannot handle these
+-- additions. The full version of Ada.Exceptions can be found in the files
+-- a-except-2005.ads/adb, and is used for all other builds where full Ada
+-- 2005 functionality is required. in particular, it is used for building
+-- run times on all targets.
+
+pragma Polling (Off);
+-- We must turn polling off for this unit, because otherwise we get
+-- elaboration circularities with ourself.
+
+with System;
+with System.Parameters;
+with System.Standard_Library;
+with System.Traceback_Entries;
+
+package Ada.Exceptions is
+ pragma Warnings (Off);
+ pragma Preelaborate_05;
+ pragma Warnings (On);
+ -- In accordance with Ada 2005 AI-362. The warnings pragmas are so that we
+ -- can compile this using older compiler versions, which will ignore the
+ -- pragma, which is fine for the bootstrap.
+
+ type Exception_Id is private;
+ Null_Id : constant Exception_Id;
+
+ type Exception_Occurrence is limited private;
+ type Exception_Occurrence_Access is access all Exception_Occurrence;
+
+ Null_Occurrence : constant Exception_Occurrence;
+
+ function Exception_Name (X : Exception_Occurrence) return String;
+ -- Same as Exception_Name (Exception_Identity (X))
+
+ function Exception_Name (Id : Exception_Id) return String;
+
+ procedure Raise_Exception (E : Exception_Id; Message : String := "");
+ -- Note: it would be really nice to give a pragma No_Return for this
+ -- procedure, but it would be wrong, since Raise_Exception does return
+ -- if given the null exception. However we do special case the name in
+ -- the test in the compiler for issuing a warning for a missing return
+ -- after this call. Program_Error seems reasonable enough in such a case.
+ -- See also the routine Raise_Exception_Always in the private part.
+
+ function Exception_Message (X : Exception_Occurrence) return String;
+
+ procedure Reraise_Occurrence (X : Exception_Occurrence);
+ -- Note: it would be really nice to give a pragma No_Return for this
+ -- procedure, but it would be wrong, since Reraise_Occurrence does return
+ -- if the argument is the null exception occurrence. See also procedure
+ -- Reraise_Occurrence_Always in the private part of this package.
+
+ function Exception_Identity (X : Exception_Occurrence) return Exception_Id;
+
+ function Exception_Information (X : Exception_Occurrence) return String;
+ -- The format of the exception information is as follows:
+ --
+ -- exception name (as in Exception_Name)
+ -- message (or a null line if no message)
+ -- PID=nnnn
+ -- 0xyyyyyyyy 0xyyyyyyyy ...
+ --
+ -- The lines are separated by a ASCII.LF character
+ -- The nnnn is the partition Id given as decimal digits.
+ -- The 0x... line represents traceback program counter locations,
+ -- in order with the first one being the exception location.
+
+ -- Note on ordering: the compiler uses the Save_Occurrence procedure, but
+ -- not the function from Rtsfind, so it is important that the procedure
+ -- come first, since Rtsfind finds the first matching entity.
+
+ procedure Save_Occurrence
+ (Target : out Exception_Occurrence;
+ Source : Exception_Occurrence);
+
+ function Save_Occurrence
+ (Source : Exception_Occurrence)
+ return Exception_Occurrence_Access;
+
+private
+ package SSL renames System.Standard_Library;
+ package SP renames System.Parameters;
+
+ subtype EOA is Exception_Occurrence_Access;
+
+ Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length;
+
+ ------------------
+ -- Exception_Id --
+ ------------------
+
+ subtype Code_Loc is System.Address;
+ -- Code location used in building exception tables and for call addresses
+ -- when propagating an exception. Values of this type are created by using
+ -- Label'Address or extracted from machine states using Get_Code_Loc.
+
+ Null_Loc : constant Code_Loc := System.Null_Address;
+ -- Null code location, used to flag outer level frame
+
+ type Exception_Id is new SSL.Exception_Data_Ptr;
+
+ function EId_To_String (X : Exception_Id) return String;
+ function String_To_EId (S : String) return Exception_Id;
+ pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String);
+ -- Functions for implementing Exception_Id stream attributes
+
+ Null_Id : constant Exception_Id := null;
+
+ -------------------------
+ -- Private Subprograms --
+ -------------------------
+
+ function Current_Target_Exception return Exception_Occurrence;
+ pragma Export
+ (Ada, Current_Target_Exception,
+ "__gnat_current_target_exception");
+ -- This routine should return the current raised exception on targets
+ -- which have built-in exception handling such as the Java Virtual
+ -- Machine. For other targets this routine is simply ignored. Currently,
+ -- only JGNAT uses this. See 4jexcept.ads for details. The pragma Export
+ -- allows this routine to be accessed elsewhere in the run-time, even
+ -- though it is in the private part of this package (it is not allowed
+ -- to be in the visible part, since this is set by the reference manual).
+
+ function Exception_Name_Simple (X : Exception_Occurrence) return String;
+ -- Like Exception_Name, but returns the simple non-qualified name of the
+ -- exception. This is used to implement the Exception_Name function in
+ -- Current_Exceptions (the DEC compatible unit). It is called from the
+ -- compiler generated code (using Rtsfind, which does not respect the
+ -- private barrier, so we can place this function in the private part
+ -- where the compiler can find it, but the spec is unchanged.)
+
+ procedure Raise_Exception_Always (E : Exception_Id; Message : String := "");
+ pragma No_Return (Raise_Exception_Always);
+ pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
+ -- This differs from Raise_Exception only in that the caller has determined
+ -- that for sure the parameter E is not null, and that therefore the call
+ -- to this procedure cannot return. The expander converts Raise_Exception
+ -- calls to Raise_Exception_Always if it can determine this is the case.
+ -- The Export allows this routine to be accessed from Pure units.
+
+ procedure Raise_From_Signal_Handler
+ (E : Exception_Id;
+ M : System.Address);
+ pragma Export
+ (Ada, Raise_From_Signal_Handler,
+ "ada__exceptions__raise_from_signal_handler");
+ pragma No_Return (Raise_From_Signal_Handler);
+ -- This routine is used to raise an exception from a signal handler. The
+ -- signal handler has already stored the machine state (i.e. the state that
+ -- corresponds to the location at which the signal was raised). E is the
+ -- Exception_Id specifying what exception is being raised, and M is a
+ -- pointer to a null-terminated string which is the message to be raised.
+ -- Note that this routine never returns, so it is permissible to simply
+ -- jump to this routine, rather than call it. This may be appropriate for
+ -- systems where the right way to get out of signal handler is to alter the
+ -- PC value in the machine state or in some other way ask the operating
+ -- system to return here rather than to the original location.
+
+ procedure Reraise_Occurrence_Always (X : Exception_Occurrence);
+ pragma No_Return (Reraise_Occurrence_Always);
+ -- This differs from Raise_Occurrence only in that the caller guarantees
+ -- that for sure the parameter X is not the null occurrence, and that
+ -- therefore this procedure cannot return. The expander uses this routine
+ -- in the translation of a raise statement with no parameter (reraise).
+
+ procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence);
+ pragma No_Return (Reraise_Occurrence_No_Defer);
+ -- Exactly like Reraise_Occurrence, except that abort is not deferred
+ -- before the call and the parameter X is known not to be the null
+ -- occurrence. This is used in generated code when it is known that
+ -- abort is already deferred.
+
+ -----------------------
+ -- Polling Interface --
+ -----------------------
+
+ -- The GNAT compiler has an option to generate polling calls to the Poll
+ -- routine in this package. Specifying the -gnatP option for a compilation
+ -- causes a call to Ada.Exceptions.Poll to be generated on every subprogram
+ -- entry and on every iteration of a loop, thus avoiding the possibility of
+ -- a case of unbounded time between calls.
+
+ -- This polling interface may be used for instrumentation or debugging
+ -- purposes (e.g. implementing watchpoints in software or in the debugger).
+
+ -- In the GNAT technology itself, this interface is used to implement
+ -- immediate aynschronous transfer of control and immediate abort on
+ -- targets which do not provide for one thread interrupting another.
+
+ -- Note: this used to be in a separate unit called System.Poll, but that
+ -- caused horrible circular elaboration problems between System.Poll and
+ -- Ada.Exceptions. One way of solving such circularities is unification!
+
+ procedure Poll;
+ -- Check for asynchronous abort. Note that we do not inline the body.
+ -- This makes the interface more useful for debugging purposes.
+
+ --------------------------
+ -- Exception_Occurrence --
+ --------------------------
+
+ package TBE renames System.Traceback_Entries;
+
+ Max_Tracebacks : constant := 50;
+ -- Maximum number of trace backs stored in exception occurrence
+
+ type Tracebacks_Array is array (1 .. Max_Tracebacks) of TBE.Traceback_Entry;
+ -- Traceback array stored in exception occurrence
+
+ type Exception_Occurrence is record
+ Id : Exception_Id;
+ -- Exception_Identity for this exception occurrence
+ -- WARNING System.System.Finalization_Implementation.Finalize_List
+ -- relies on the fact that this field is always first in the exception
+ -- occurrence
+
+ Msg_Length : Natural := 0;
+ -- Length of message (zero = no message)
+
+ Msg : String (1 .. Exception_Msg_Max_Length);
+ -- Characters of message
+
+ Cleanup_Flag : Boolean := False;
+ -- The cleanup flag is normally False, it is set True for an exception
+ -- occurrence passed to a cleanup routine, and will still be set True
+ -- when the cleanup routine does a Reraise_Occurrence call using this
+ -- exception occurrence. This is used to avoid recording a bogus trace
+ -- back entry from this reraise call.
+
+ Exception_Raised : Boolean := False;
+ -- Set to true to indicate that this exception occurrence has actually
+ -- been raised. When an exception occurrence is first created, this is
+ -- set to False, then when it is processed by Raise_Current_Exception,
+ -- it is set to True. If Raise_Current_Exception is used to raise an
+ -- exception for which this flag is already True, then it knows that
+ -- it is dealing with the reraise case (which is useful to distinguish
+ -- for exception tracing purposes).
+
+ Pid : Natural := 0;
+ -- Partition_Id for partition raising exception
+
+ Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0;
+ -- Number of traceback entries stored
+
+ Tracebacks : Tracebacks_Array;
+ -- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks))
+
+ Private_Data : System.Address := System.Null_Address;
+ -- Field used by low level exception mechanism to store specific data.
+ -- Currently used by the GCC exception mechanism to store a pointer to
+ -- a GNAT_GCC_Exception.
+ end record;
+
+ function "=" (Left, Right : Exception_Occurrence) return Boolean
+ is abstract;
+ -- Don't allow comparison on exception occurrences, we should not need
+ -- this, and it would not work right, because of the Msg and Tracebacks
+ -- fields which have unused entries not copied by Save_Occurrence.
+
+ function EO_To_String (X : Exception_Occurrence) return String;
+ function String_To_EO (S : String) return Exception_Occurrence;
+ pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String);
+ -- Functions for implementing Exception_Occurrence stream attributes
+
+ Null_Occurrence : constant Exception_Occurrence := (
+ Id => null,
+ Msg_Length => 0,
+ Msg => (others => ' '),
+ Cleanup_Flag => False,
+ Exception_Raised => False,
+ Pid => 0,
+ Num_Tracebacks => 0,
+ Tracebacks => (others => TBE.Null_TB_Entry),
+ Private_Data => System.Null_Address);
+
+end Ada.Exceptions;