350 lines
16 KiB
Ada
350 lines
16 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- A D A . E X C E P T I O N S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2015, Free Software Foundation, Inc. --
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-- --
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-- This specification is derived from the Ada Reference Manual for use with --
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-- GNAT. The copyright notice above, and the license provisions that follow --
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-- apply solely to the contents of the part following the private keyword. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This version of Ada.Exceptions fully supports Ada 95 and later language
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-- versions. It is used in all situations except for the build of the
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-- compiler and other basic tools. For these latter builds, we use an
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-- Ada 95-only version.
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-- The reason for this splitting off of a separate version is to support
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-- older bootstrap compilers that do not support Ada 2005 features, and
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-- Ada.Exceptions is part of the compiler sources.
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pragma Polling (Off);
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-- We must turn polling off for this unit, because otherwise we get
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-- elaboration circularities with ourself.
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with System;
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with System.Parameters;
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with System.Standard_Library;
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with System.Traceback_Entries;
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package Ada.Exceptions is
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pragma Preelaborate;
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-- In accordance with Ada 2005 AI-362.
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type Exception_Id is private;
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pragma Preelaborable_Initialization (Exception_Id);
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Null_Id : constant Exception_Id;
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type Exception_Occurrence is limited private;
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pragma Preelaborable_Initialization (Exception_Occurrence);
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type Exception_Occurrence_Access is access all Exception_Occurrence;
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Null_Occurrence : constant Exception_Occurrence;
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function Exception_Name (Id : Exception_Id) return String;
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function Exception_Name (X : Exception_Occurrence) return String;
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function Wide_Exception_Name
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(Id : Exception_Id) return Wide_String;
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pragma Ada_05 (Wide_Exception_Name);
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function Wide_Exception_Name
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(X : Exception_Occurrence) return Wide_String;
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pragma Ada_05 (Wide_Exception_Name);
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function Wide_Wide_Exception_Name
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(Id : Exception_Id) return Wide_Wide_String;
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pragma Ada_05 (Wide_Wide_Exception_Name);
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function Wide_Wide_Exception_Name
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(X : Exception_Occurrence) return Wide_Wide_String;
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pragma Ada_05 (Wide_Wide_Exception_Name);
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procedure Raise_Exception (E : Exception_Id; Message : String := "");
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pragma No_Return (Raise_Exception);
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-- Note: In accordance with AI-466, CE is raised if E = Null_Id
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function Exception_Message (X : Exception_Occurrence) return String;
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procedure Reraise_Occurrence (X : Exception_Occurrence);
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-- Note: it would be really nice to give a pragma No_Return for this
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-- procedure, but it would be wrong, since Reraise_Occurrence does return
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-- if the argument is the null exception occurrence. See also procedure
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-- Reraise_Occurrence_Always in the private part of this package.
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function Exception_Identity (X : Exception_Occurrence) return Exception_Id;
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function Exception_Information (X : Exception_Occurrence) return String;
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-- The format of the exception information is as follows:
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--
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-- exception name (as in Exception_Name)
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-- message (or a null line if no message)
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-- PID=nnnn
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-- 0xyyyyyyyy 0xyyyyyyyy ...
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--
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-- The lines are separated by a ASCII.LF character
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--
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-- The nnnn is the partition Id given as decimal digits
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--
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-- The 0x... line represents traceback program counter locations,
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-- in order with the first one being the exception location.
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-- Note on ordering: the compiler uses the Save_Occurrence procedure, but
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-- not the function from Rtsfind, so it is important that the procedure
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-- come first, since Rtsfind finds the first matching entity.
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procedure Save_Occurrence
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(Target : out Exception_Occurrence;
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Source : Exception_Occurrence);
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function Save_Occurrence
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(Source : Exception_Occurrence)
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return Exception_Occurrence_Access;
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-- Ada 2005 (AI-438): The language revision introduces the following
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-- subprograms and attribute definitions. We do not provide them
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-- explicitly. instead, the corresponding stream attributes are made
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-- available through a pragma Stream_Convert in the private part.
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-- procedure Read_Exception_Occurrence
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-- (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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-- Item : out Exception_Occurrence);
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-- procedure Write_Exception_Occurrence
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-- (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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-- Item : Exception_Occurrence);
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-- for Exception_Occurrence'Read use Read_Exception_Occurrence;
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-- for Exception_Occurrence'Write use Write_Exception_Occurrence;
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private
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package SSL renames System.Standard_Library;
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package SP renames System.Parameters;
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subtype EOA is Exception_Occurrence_Access;
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Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length;
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------------------
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-- Exception_Id --
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------------------
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subtype Code_Loc is System.Address;
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-- Code location used in building exception tables and for call addresses
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-- when propagating an exception. Values of this type are created by using
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-- Label'Address or extracted from machine states using Get_Code_Loc.
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Null_Loc : constant Code_Loc := System.Null_Address;
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-- Null code location, used to flag outer level frame
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type Exception_Id is new SSL.Exception_Data_Ptr;
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function EId_To_String (X : Exception_Id) return String;
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function String_To_EId (S : String) return Exception_Id;
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pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String);
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-- Functions for implementing Exception_Id stream attributes
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Null_Id : constant Exception_Id := null;
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-------------------------
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-- Private Subprograms --
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-------------------------
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function Exception_Name_Simple (X : Exception_Occurrence) return String;
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-- Like Exception_Name, but returns the simple non-qualified name of the
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-- exception. This is used to implement the Exception_Name function in
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-- Current_Exceptions (the DEC compatible unit). It is called from the
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-- compiler generated code (using Rtsfind, which does not respect the
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-- private barrier, so we can place this function in the private part
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-- where the compiler can find it, but the spec is unchanged.)
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procedure Raise_Exception_Always (E : Exception_Id; Message : String := "");
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pragma No_Return (Raise_Exception_Always);
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pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
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-- This differs from Raise_Exception only in that the caller has determined
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-- that for sure the parameter E is not null, and that therefore no check
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-- for Null_Id is required. The expander converts Raise_Exception calls to
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-- Raise_Exception_Always if it can determine this is the case. The Export
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-- allows this routine to be accessed from Pure units.
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procedure Raise_From_Signal_Handler
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(E : Exception_Id;
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M : System.Address);
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pragma Export
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(Ada, Raise_From_Signal_Handler,
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"ada__exceptions__raise_from_signal_handler");
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pragma No_Return (Raise_From_Signal_Handler);
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-- This routine is used to raise an exception from a signal handler. The
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-- signal handler has already stored the machine state (i.e. the state that
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-- corresponds to the location at which the signal was raised). E is the
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-- Exception_Id specifying what exception is being raised, and M is a
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-- pointer to a null-terminated string which is the message to be raised.
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-- Note that this routine never returns, so it is permissible to simply
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-- jump to this routine, rather than call it. This may be appropriate for
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-- systems where the right way to get out of signal handler is to alter the
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-- PC value in the machine state or in some other way ask the operating
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-- system to return here rather than to the original location.
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procedure Raise_From_Controlled_Operation
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(X : Ada.Exceptions.Exception_Occurrence);
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pragma No_Return (Raise_From_Controlled_Operation);
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pragma Export
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(Ada, Raise_From_Controlled_Operation,
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"__gnat_raise_from_controlled_operation");
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-- Raise Program_Error, providing information about X (an exception raised
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-- during a controlled operation) in the exception message.
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procedure Reraise_Library_Exception_If_Any;
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pragma Export
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(Ada, Reraise_Library_Exception_If_Any,
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"__gnat_reraise_library_exception_if_any");
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-- If there was an exception raised during library-level finalization,
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-- reraise the exception.
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procedure Reraise_Occurrence_Always (X : Exception_Occurrence);
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pragma No_Return (Reraise_Occurrence_Always);
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-- This differs from Raise_Occurrence only in that the caller guarantees
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-- that for sure the parameter X is not the null occurrence, and that
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-- therefore this procedure cannot return. The expander uses this routine
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-- in the translation of a raise statement with no parameter (reraise).
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procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence);
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pragma No_Return (Reraise_Occurrence_No_Defer);
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-- Exactly like Reraise_Occurrence, except that abort is not deferred
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-- before the call and the parameter X is known not to be the null
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-- occurrence. This is used in generated code when it is known that abort
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-- is already deferred.
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function Triggered_By_Abort return Boolean;
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-- Determine whether the current exception (if it exists) is an instance of
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-- Standard'Abort_Signal.
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-----------------------
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-- Polling Interface --
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-----------------------
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-- The GNAT compiler has an option to generate polling calls to the Poll
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-- routine in this package. Specifying the -gnatP option for a compilation
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-- causes a call to Ada.Exceptions.Poll to be generated on every subprogram
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-- entry and on every iteration of a loop, thus avoiding the possibility of
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-- a case of unbounded time between calls.
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-- This polling interface may be used for instrumentation or debugging
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-- purposes (e.g. implementing watchpoints in software or in the debugger).
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-- In the GNAT technology itself, this interface is used to implement
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-- immediate asynchronous transfer of control and immediate abort on
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-- targets which do not provide for one thread interrupting another.
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-- Note: this used to be in a separate unit called System.Poll, but that
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-- caused horrible circular elaboration problems between System.Poll and
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-- Ada.Exceptions.
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procedure Poll;
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-- Check for asynchronous abort. Note that we do not inline the body.
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-- This makes the interface more useful for debugging purposes.
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--------------------------
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-- Exception_Occurrence --
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--------------------------
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package TBE renames System.Traceback_Entries;
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Max_Tracebacks : constant := 50;
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-- Maximum number of trace backs stored in exception occurrence
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subtype Tracebacks_Array is TBE.Tracebacks_Array (1 .. Max_Tracebacks);
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-- Traceback array stored in exception occurrence
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type Exception_Occurrence is record
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Id : Exception_Id;
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-- Exception_Identity for this exception occurrence
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Machine_Occurrence : System.Address;
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-- The underlying machine occurrence. For GCC, this corresponds to the
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-- _Unwind_Exception structure address.
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Msg_Length : Natural := 0;
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-- Length of message (zero = no message)
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Msg : String (1 .. Exception_Msg_Max_Length);
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-- Characters of message
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Exception_Raised : Boolean := False;
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-- Set to true to indicate that this exception occurrence has actually
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-- been raised. When an exception occurrence is first created, this is
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-- set to False, then when it is processed by Raise_Current_Exception,
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-- it is set to True. If Raise_Current_Exception is used to raise an
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-- exception for which this flag is already True, then it knows that
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-- it is dealing with the reraise case (which is useful to distinguish
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-- for exception tracing purposes).
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Pid : Natural := 0;
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-- Partition_Id for partition raising exception
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Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0;
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-- Number of traceback entries stored
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Tracebacks : Tracebacks_Array;
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-- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks))
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end record;
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function "=" (Left, Right : Exception_Occurrence) return Boolean
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is abstract;
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-- Don't allow comparison on exception occurrences, we should not need
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-- this, and it would not work right, because of the Msg and Tracebacks
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-- fields which have unused entries not copied by Save_Occurrence.
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function Get_Exception_Machine_Occurrence
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(X : Exception_Occurrence) return System.Address;
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pragma Export (Ada, Get_Exception_Machine_Occurrence,
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"__gnat_get_exception_machine_occurrence");
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-- Get the machine occurrence corresponding to an exception occurrence.
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-- It is Null_Address if there is no machine occurrence (in runtimes that
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-- doesn't use GCC mechanism) or if it has been lost (Save_Occurrence
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-- doesn't save the machine occurrence).
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function EO_To_String (X : Exception_Occurrence) return String;
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function String_To_EO (S : String) return Exception_Occurrence;
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pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String);
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-- Functions for implementing Exception_Occurrence stream attributes
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Null_Occurrence : constant Exception_Occurrence := (
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Id => null,
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Machine_Occurrence => System.Null_Address,
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Msg_Length => 0,
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Msg => (others => ' '),
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Exception_Raised => False,
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Pid => 0,
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Num_Tracebacks => 0,
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Tracebacks => (others => TBE.Null_TB_Entry));
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end Ada.Exceptions;
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