329 lines
16 KiB
Ada
329 lines
16 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- GNAT RUN-TIME COMPONENTS --
|
|
-- --
|
|
-- A D A . E X C E P T I O N S --
|
|
-- --
|
|
-- S p e c --
|
|
-- --
|
|
-- Copyright (C) 1992-2007, 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. It omits Ada 2005
|
|
-- features such as 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);
|
|
-- We make this preelaborable in Ada 2005 mode. If we did not do this, then
|
|
-- run time units used by the compiler (e.g. s-soflin.ads) would run
|
|
-- into trouble. Conformance is not an issue, since this version is used
|
|
-- only by the compiler.
|
|
|
|
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 in Ada 95 mode. 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 Raise_From_Controlled_Operation
|
|
(X : Ada.Exceptions.Exception_Occurrence);
|
|
pragma No_Return (Raise_From_Controlled_Operation);
|
|
-- Raise Program_Error, proviving information about X (an exception
|
|
-- raised during a controlled operation) in the exception message.
|
|
|
|
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;
|