1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                       A D A . E X C E P T I O N S                        --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2020, Free Software Foundation, Inc.         --
10--                                                                          --
11-- This specification is derived from the Ada Reference Manual for use with --
12-- GNAT. The copyright notice above, and the license provisions that follow --
13-- apply solely to the  contents of the part following the private keyword. --
14--                                                                          --
15-- GNAT is free software;  you can  redistribute it  and/or modify it under --
16-- terms of the  GNU General Public License as published  by the Free Soft- --
17-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
18-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
19-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
20-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
21--                                                                          --
22-- As a special exception under Section 7 of GPL version 3, you are granted --
23-- additional permissions described in the GCC Runtime Library Exception,   --
24-- version 3.1, as published by the Free Software Foundation.               --
25--                                                                          --
26-- You should have received a copy of the GNU General Public License and    --
27-- a copy of the GCC Runtime Library Exception along with this program;     --
28-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
29-- <http://www.gnu.org/licenses/>.                                          --
30--                                                                          --
31-- GNAT was originally developed  by the GNAT team at  New York University. --
32-- Extensive contributions were provided by Ada Core Technologies Inc.      --
33--                                                                          --
34------------------------------------------------------------------------------
35
36--  This is the default version of this package. We also have cert and zfp
37--  versions.
38
39with System;
40with System.Parameters;
41with System.Standard_Library;
42with System.Traceback_Entries;
43
44package Ada.Exceptions is
45   pragma Preelaborate;
46   --  In accordance with Ada 2005 AI-362.
47
48   type Exception_Id is private;
49   pragma Preelaborable_Initialization (Exception_Id);
50
51   Null_Id : constant Exception_Id;
52
53   type Exception_Occurrence is limited private;
54   pragma Preelaborable_Initialization (Exception_Occurrence);
55
56   type Exception_Occurrence_Access is access all Exception_Occurrence;
57
58   Null_Occurrence : constant Exception_Occurrence;
59
60   function Exception_Name (Id : Exception_Id) return String;
61
62   function Exception_Name (X : Exception_Occurrence) return String;
63
64   function Wide_Exception_Name
65     (Id : Exception_Id) return Wide_String;
66   pragma Ada_05 (Wide_Exception_Name);
67
68   function Wide_Exception_Name
69     (X : Exception_Occurrence) return Wide_String;
70   pragma Ada_05 (Wide_Exception_Name);
71
72   function Wide_Wide_Exception_Name
73     (Id : Exception_Id) return Wide_Wide_String;
74   pragma Ada_05 (Wide_Wide_Exception_Name);
75
76   function Wide_Wide_Exception_Name
77     (X : Exception_Occurrence) return Wide_Wide_String;
78   pragma Ada_05 (Wide_Wide_Exception_Name);
79
80   procedure Raise_Exception (E : Exception_Id; Message : String := "");
81   pragma No_Return (Raise_Exception);
82   --  Note: In accordance with AI-466, CE is raised if E = Null_Id
83
84   function Exception_Message (X : Exception_Occurrence) return String;
85
86   procedure Reraise_Occurrence (X : Exception_Occurrence);
87   --  Note: it would be really nice to give a pragma No_Return for this
88   --  procedure, but it would be wrong, since Reraise_Occurrence does return
89   --  if the argument is the null exception occurrence. See also procedure
90   --  Reraise_Occurrence_Always in the private part of this package.
91
92   function Exception_Identity (X : Exception_Occurrence) return Exception_Id;
93
94   function Exception_Information (X : Exception_Occurrence) return String;
95   --  The format of the exception information is as follows:
96   --
97   --    exception name (as in Exception_Name)
98   --    message (or a null line if no message)
99   --    PID=nnnn
100   --    0xyyyyyyyy 0xyyyyyyyy ...
101   --
102   --  The lines are separated by a ASCII.LF character
103   --
104   --  The nnnn is the partition Id given as decimal digits
105   --
106   --  The 0x... line represents traceback program counter locations,
107   --  in order with the first one being the exception location.
108
109   --  Note on ordering: the compiler uses the Save_Occurrence procedure, but
110   --  not the function from Rtsfind, so it is important that the procedure
111   --  come first, since Rtsfind finds the first matching entity.
112
113   procedure Save_Occurrence
114     (Target : out Exception_Occurrence;
115      Source : Exception_Occurrence);
116
117   function Save_Occurrence
118     (Source : Exception_Occurrence)
119      return   Exception_Occurrence_Access;
120
121   --  Ada 2005 (AI-438): The language revision introduces the following
122   --  subprograms and attribute definitions. We do not provide them
123   --  explicitly. instead, the corresponding stream attributes are made
124   --  available through a pragma Stream_Convert in the private part.
125
126   --  procedure Read_Exception_Occurrence
127   --    (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
128   --     Item   : out Exception_Occurrence);
129
130   --  procedure Write_Exception_Occurrence
131   --    (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
132   --     Item   : Exception_Occurrence);
133
134   --  for Exception_Occurrence'Read use Read_Exception_Occurrence;
135   --  for Exception_Occurrence'Write use Write_Exception_Occurrence;
136
137private
138   package SSL renames System.Standard_Library;
139   package SP renames System.Parameters;
140
141   subtype EOA is Exception_Occurrence_Access;
142
143   Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length;
144
145   ------------------
146   -- Exception_Id --
147   ------------------
148
149   subtype Code_Loc is System.Address;
150   --  Code location used in building exception tables and for call addresses
151   --  when propagating an exception. Values of this type are created by using
152   --  Label'Address or extracted from machine states using Get_Code_Loc.
153
154   Null_Loc : constant Code_Loc := System.Null_Address;
155   --  Null code location, used to flag outer level frame
156
157   type Exception_Id is new SSL.Exception_Data_Ptr;
158
159   function EId_To_String (X : Exception_Id) return String;
160   function String_To_EId (S : String) return Exception_Id;
161   pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String);
162   --  Functions for implementing Exception_Id stream attributes
163
164   Null_Id : constant Exception_Id := null;
165
166   -------------------------
167   -- Private Subprograms --
168   -------------------------
169
170   function Exception_Name_Simple (X : Exception_Occurrence) return String;
171   --  Like Exception_Name, but returns the simple non-qualified name of the
172   --  exception. This is used to implement the Exception_Name function in
173   --  Current_Exceptions (the DEC compatible unit). It is called from the
174   --  compiler generated code (using Rtsfind, which does not respect the
175   --  private barrier, so we can place this function in the private part
176   --  where the compiler can find it, but the spec is unchanged.)
177
178   procedure Raise_Exception_Always (E : Exception_Id; Message : String := "");
179   pragma No_Return (Raise_Exception_Always);
180   pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
181   --  This differs from Raise_Exception only in that the caller has determined
182   --  that for sure the parameter E is not null, and that therefore no check
183   --  for Null_Id is required. The expander converts Raise_Exception calls to
184   --  Raise_Exception_Always if it can determine this is the case. The Export
185   --  allows this routine to be accessed from Pure units.
186
187   procedure Raise_From_Signal_Handler
188     (E : Exception_Id;
189      M : System.Address);
190   pragma Export
191     (Ada, Raise_From_Signal_Handler,
192           "ada__exceptions__raise_from_signal_handler");
193   pragma No_Return (Raise_From_Signal_Handler);
194   --  This routine is used to raise an exception from a signal handler. The
195   --  signal handler has already stored the machine state (i.e. the state that
196   --  corresponds to the location at which the signal was raised). E is the
197   --  Exception_Id specifying what exception is being raised, and M is a
198   --  pointer to a null-terminated string which is the message to be raised.
199   --  Note that this routine never returns, so it is permissible to simply
200   --  jump to this routine, rather than call it. This may be appropriate for
201   --  systems where the right way to get out of signal handler is to alter the
202   --  PC value in the machine state or in some other way ask the operating
203   --  system to return here rather than to the original location.
204
205   procedure Raise_From_Controlled_Operation
206     (X : Ada.Exceptions.Exception_Occurrence);
207   pragma No_Return (Raise_From_Controlled_Operation);
208   pragma Export
209     (Ada, Raise_From_Controlled_Operation,
210           "__gnat_raise_from_controlled_operation");
211   --  Raise Program_Error, providing information about X (an exception raised
212   --  during a controlled operation) in the exception message.
213
214   procedure Reraise_Library_Exception_If_Any;
215   pragma Export
216     (Ada, Reraise_Library_Exception_If_Any,
217           "__gnat_reraise_library_exception_if_any");
218   --  If there was an exception raised during library-level finalization,
219   --  reraise the exception.
220
221   procedure Reraise_Occurrence_Always (X : Exception_Occurrence);
222   pragma No_Return (Reraise_Occurrence_Always);
223   --  This differs from Raise_Occurrence only in that the caller guarantees
224   --  that for sure the parameter X is not the null occurrence, and that
225   --  therefore this procedure cannot return. The expander uses this routine
226   --  in the translation of a raise statement with no parameter (reraise).
227
228   procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence);
229   pragma No_Return (Reraise_Occurrence_No_Defer);
230   --  Exactly like Reraise_Occurrence, except that abort is not deferred
231   --  before the call and the parameter X is known not to be the null
232   --  occurrence. This is used in generated code when it is known that abort
233   --  is already deferred.
234
235   function Triggered_By_Abort return Boolean;
236   --  Determine whether the current exception (if it exists) is an instance of
237   --  Standard'Abort_Signal.
238
239   --------------------------
240   -- Exception_Occurrence --
241   --------------------------
242
243   package TBE renames System.Traceback_Entries;
244
245   Max_Tracebacks : constant := 50;
246   --  Maximum number of trace backs stored in exception occurrence
247
248   subtype Tracebacks_Array is TBE.Tracebacks_Array (1 .. Max_Tracebacks);
249   --  Traceback array stored in exception occurrence
250
251   type Exception_Occurrence is record
252      Id : Exception_Id := Null_Id;
253      --  Exception_Identity for this exception occurrence
254
255      Machine_Occurrence : System.Address;
256      --  The underlying machine occurrence. For GCC, this corresponds to the
257      --  _Unwind_Exception structure address.
258
259      Msg_Length : Natural := 0;
260      --  Length of message (zero = no message)
261
262      Msg : String (1 .. Exception_Msg_Max_Length);
263      --  Characters of message
264
265      Exception_Raised : Boolean := False;
266      --  Set to true to indicate that this exception occurrence has actually
267      --  been raised. When an exception occurrence is first created, this is
268      --  set to False, then when it is processed by Raise_Current_Exception,
269      --  it is set to True. If Raise_Current_Exception is used to raise an
270      --  exception for which this flag is already True, then it knows that
271      --  it is dealing with the reraise case (which is useful to distinguish
272      --  for exception tracing purposes).
273
274      Pid : Natural := 0;
275      --  Partition_Id for partition raising exception
276
277      Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0;
278      --  Number of traceback entries stored
279
280      Tracebacks : Tracebacks_Array;
281      --  Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks))
282   end record;
283
284   function "=" (Left, Right : Exception_Occurrence) return Boolean
285     is abstract;
286   --  Don't allow comparison on exception occurrences, we should not need
287   --  this, and it would not work right, because of the Msg and Tracebacks
288   --  fields which have unused entries not copied by Save_Occurrence.
289
290   function Get_Exception_Machine_Occurrence
291     (X : Exception_Occurrence) return System.Address;
292   pragma Export (Ada, Get_Exception_Machine_Occurrence,
293                  "__gnat_get_exception_machine_occurrence");
294   --  Get the machine occurrence corresponding to an exception occurrence.
295   --  It is Null_Address if there is no machine occurrence (in runtimes that
296   --  doesn't use GCC mechanism) or if it has been lost (Save_Occurrence
297   --  doesn't save the machine occurrence).
298
299   function EO_To_String (X : Exception_Occurrence) return String;
300   function String_To_EO (S : String) return Exception_Occurrence;
301   pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String);
302   --  Functions for implementing Exception_Occurrence stream attributes
303
304   pragma Warnings (Off, "aggregate not fully initialized");
305   Null_Occurrence : constant Exception_Occurrence := (others => <>);
306   pragma Warnings (On, "aggregate not fully initialized");
307
308end Ada.Exceptions;
309