------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- A D A . E X C E P T I O N S -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2018, 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 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 -- -- . -- -- -- -- 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 fully supports Ada 95 and later language -- versions. It is used in all situations except for the build of the -- compiler and other basic tools. For these latter builds, we use an -- Ada 95-only version. -- The reason for this splitting off of a separate version is to support -- older bootstrap compilers that do not support Ada 2005 features, and -- Ada.Exceptions is part of the compiler sources. 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 Preelaborate; -- In accordance with Ada 2005 AI-362. type Exception_Id is private; pragma Preelaborable_Initialization (Exception_Id); Null_Id : constant Exception_Id; type Exception_Occurrence is limited private; pragma Preelaborable_Initialization (Exception_Occurrence); 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 := ""); pragma No_Return (Raise_Exception); -- Note: In accordance with AI-466, CE is raised if E = Null_Id 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; -- Ada 2005 (AI-438): The language revision introduces the following -- subprograms and attribute definitions. We do not provide them -- explicitly. instead, the corresponding stream attributes are made -- available through a pragma Stream_Convert in the private part. -- procedure Read_Exception_Occurrence -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; -- Item : out Exception_Occurrence); -- procedure Write_Exception_Occurrence -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; -- Item : Exception_Occurrence); -- for Exception_Occurrence'Read use Read_Exception_Occurrence; -- for Exception_Occurrence'Write use Write_Exception_Occurrence; 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 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 no check -- for Null_Id is required. 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); pragma Export (Ada, Raise_From_Controlled_Operation, "__gnat_raise_from_controlled_operation"); -- Raise Program_Error, providing information about X (an exception raised -- during a controlled operation) in the exception message. procedure Reraise_Library_Exception_If_Any; pragma Export (Ada, Reraise_Library_Exception_If_Any, "__gnat_reraise_library_exception_if_any"); -- If there was an exception raised during library-level finalization, -- reraise the exception. 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. function Triggered_By_Abort return Boolean; -- Determine whether the current exception (if it exists) is an instance of -- Standard'Abort_Signal. ----------------------- -- 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 asynchronous 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. 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 subtype Tracebacks_Array is TBE.Tracebacks_Array (1 .. Max_Tracebacks); -- Traceback array stored in exception occurrence type Exception_Occurrence is record Id : Exception_Id; -- Exception_Identity for this exception occurrence Machine_Occurrence : System.Address; -- The underlying machine occurrence. For GCC, this corresponds to the -- _Unwind_Exception structure address. Msg_Length : Natural := 0; -- Length of message (zero = no message) Msg : String (1 .. Exception_Msg_Max_Length); -- Characters of message 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)) 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 Get_Exception_Machine_Occurrence (X : Exception_Occurrence) return System.Address; pragma Export (Ada, Get_Exception_Machine_Occurrence, "__gnat_get_exception_machine_occurrence"); -- Get the machine occurrence corresponding to an exception occurrence. -- It is Null_Address if there is no machine occurrence (in runtimes that -- doesn't use GCC mechanism) or if it has been lost (Save_Occurrence -- doesn't save the machine 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, Machine_Occurrence => System.Null_Address, Msg_Length => 0, Msg => (others => ' '), Exception_Raised => False, Pid => 0, Num_Tracebacks => 0, Tracebacks => (others => TBE.Null_TB_Entry)); end Ada.Exceptions;