------------------------------------------------------------------------------ -- -- -- 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 is used for all Ada 2005 builds. It differs from a-except.ads -- only with respect to the addition of Wide_[Wide]Exception_Name functions. -- The additional entities are marked with pragma Ada_05, so this extended -- unit is also perfectly suitable for use in Ada 95 or Ada 83 mode. -- The reason for this splitting off of a separate version is that bootstrap -- compilers often will be used that do not support Ada 2005 features, and -- Ada.Exceptions is part of the compiler sources. -- The base version of this unit Ada.Exceptions omits the Wide version of -- Exception_Name and is used to build the compiler and other basic tools. 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 (Id : Exception_Id) return String; function Exception_Name (X : Exception_Occurrence) return String; function Wide_Exception_Name (Id : Exception_Id) return Wide_String; pragma Ada_05 (Wide_Exception_Name); function Wide_Exception_Name (X : Exception_Occurrence) return Wide_String; pragma Ada_05 (Wide_Exception_Name); function Wide_Wide_Exception_Name (Id : Exception_Id) return Wide_Wide_String; pragma Ada_05 (Wide_Wide_Exception_Name); function Wide_Wide_Exception_Name (X : Exception_Occurrence) return Wide_Wide_String; pragma Ada_05 (Wide_Wide_Exception_Name); 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;