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) 1992-2015, 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 version of Ada.Exceptions fully supports Ada 95 and later language 37-- versions. It is used in all situations except for the build of the 38-- compiler and other basic tools. For these latter builds, we use an 39-- Ada 95-only version. 40 41-- The reason for this splitting off of a separate version is to support 42-- older bootstrap compilers that do not support Ada 2005 features, and 43-- Ada.Exceptions is part of the compiler sources. 44 45pragma Polling (Off); 46-- We must turn polling off for this unit, because otherwise we get 47-- elaboration circularities with ourself. 48 49with System; 50with System.Parameters; 51with System.Standard_Library; 52with System.Traceback_Entries; 53 54package Ada.Exceptions is 55 pragma Preelaborate; 56 -- In accordance with Ada 2005 AI-362. 57 58 type Exception_Id is private; 59 pragma Preelaborable_Initialization (Exception_Id); 60 61 Null_Id : constant Exception_Id; 62 63 type Exception_Occurrence is limited private; 64 pragma Preelaborable_Initialization (Exception_Occurrence); 65 66 type Exception_Occurrence_Access is access all Exception_Occurrence; 67 68 Null_Occurrence : constant Exception_Occurrence; 69 70 function Exception_Name (Id : Exception_Id) return String; 71 72 function Exception_Name (X : Exception_Occurrence) return String; 73 74 function Wide_Exception_Name 75 (Id : Exception_Id) return Wide_String; 76 pragma Ada_05 (Wide_Exception_Name); 77 78 function Wide_Exception_Name 79 (X : Exception_Occurrence) return Wide_String; 80 pragma Ada_05 (Wide_Exception_Name); 81 82 function Wide_Wide_Exception_Name 83 (Id : Exception_Id) return Wide_Wide_String; 84 pragma Ada_05 (Wide_Wide_Exception_Name); 85 86 function Wide_Wide_Exception_Name 87 (X : Exception_Occurrence) return Wide_Wide_String; 88 pragma Ada_05 (Wide_Wide_Exception_Name); 89 90 procedure Raise_Exception (E : Exception_Id; Message : String := ""); 91 pragma No_Return (Raise_Exception); 92 -- Note: In accordance with AI-466, CE is raised if E = Null_Id 93 94 function Exception_Message (X : Exception_Occurrence) return String; 95 96 procedure Reraise_Occurrence (X : Exception_Occurrence); 97 -- Note: it would be really nice to give a pragma No_Return for this 98 -- procedure, but it would be wrong, since Reraise_Occurrence does return 99 -- if the argument is the null exception occurrence. See also procedure 100 -- Reraise_Occurrence_Always in the private part of this package. 101 102 function Exception_Identity (X : Exception_Occurrence) return Exception_Id; 103 104 function Exception_Information (X : Exception_Occurrence) return String; 105 -- The format of the exception information is as follows: 106 -- 107 -- exception name (as in Exception_Name) 108 -- message (or a null line if no message) 109 -- PID=nnnn 110 -- 0xyyyyyyyy 0xyyyyyyyy ... 111 -- 112 -- The lines are separated by a ASCII.LF character 113 -- 114 -- The nnnn is the partition Id given as decimal digits 115 -- 116 -- The 0x... line represents traceback program counter locations, 117 -- in order with the first one being the exception location. 118 119 -- Note on ordering: the compiler uses the Save_Occurrence procedure, but 120 -- not the function from Rtsfind, so it is important that the procedure 121 -- come first, since Rtsfind finds the first matching entity. 122 123 procedure Save_Occurrence 124 (Target : out Exception_Occurrence; 125 Source : Exception_Occurrence); 126 127 function Save_Occurrence 128 (Source : Exception_Occurrence) 129 return Exception_Occurrence_Access; 130 131 -- Ada 2005 (AI-438): The language revision introduces the following 132 -- subprograms and attribute definitions. We do not provide them 133 -- explicitly. instead, the corresponding stream attributes are made 134 -- available through a pragma Stream_Convert in the private part. 135 136 -- procedure Read_Exception_Occurrence 137 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 138 -- Item : out Exception_Occurrence); 139 140 -- procedure Write_Exception_Occurrence 141 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 142 -- Item : Exception_Occurrence); 143 144 -- for Exception_Occurrence'Read use Read_Exception_Occurrence; 145 -- for Exception_Occurrence'Write use Write_Exception_Occurrence; 146 147private 148 package SSL renames System.Standard_Library; 149 package SP renames System.Parameters; 150 151 subtype EOA is Exception_Occurrence_Access; 152 153 Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length; 154 155 ------------------ 156 -- Exception_Id -- 157 ------------------ 158 159 subtype Code_Loc is System.Address; 160 -- Code location used in building exception tables and for call addresses 161 -- when propagating an exception. Values of this type are created by using 162 -- Label'Address or extracted from machine states using Get_Code_Loc. 163 164 Null_Loc : constant Code_Loc := System.Null_Address; 165 -- Null code location, used to flag outer level frame 166 167 type Exception_Id is new SSL.Exception_Data_Ptr; 168 169 function EId_To_String (X : Exception_Id) return String; 170 function String_To_EId (S : String) return Exception_Id; 171 pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String); 172 -- Functions for implementing Exception_Id stream attributes 173 174 Null_Id : constant Exception_Id := null; 175 176 ------------------------- 177 -- Private Subprograms -- 178 ------------------------- 179 180 function Exception_Name_Simple (X : Exception_Occurrence) return String; 181 -- Like Exception_Name, but returns the simple non-qualified name of the 182 -- exception. This is used to implement the Exception_Name function in 183 -- Current_Exceptions (the DEC compatible unit). It is called from the 184 -- compiler generated code (using Rtsfind, which does not respect the 185 -- private barrier, so we can place this function in the private part 186 -- where the compiler can find it, but the spec is unchanged.) 187 188 procedure Raise_Exception_Always (E : Exception_Id; Message : String := ""); 189 pragma No_Return (Raise_Exception_Always); 190 pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception"); 191 -- This differs from Raise_Exception only in that the caller has determined 192 -- that for sure the parameter E is not null, and that therefore no check 193 -- for Null_Id is required. The expander converts Raise_Exception calls to 194 -- Raise_Exception_Always if it can determine this is the case. The Export 195 -- allows this routine to be accessed from Pure units. 196 197 procedure Raise_From_Signal_Handler 198 (E : Exception_Id; 199 M : System.Address); 200 pragma Export 201 (Ada, Raise_From_Signal_Handler, 202 "ada__exceptions__raise_from_signal_handler"); 203 pragma No_Return (Raise_From_Signal_Handler); 204 -- This routine is used to raise an exception from a signal handler. The 205 -- signal handler has already stored the machine state (i.e. the state that 206 -- corresponds to the location at which the signal was raised). E is the 207 -- Exception_Id specifying what exception is being raised, and M is a 208 -- pointer to a null-terminated string which is the message to be raised. 209 -- Note that this routine never returns, so it is permissible to simply 210 -- jump to this routine, rather than call it. This may be appropriate for 211 -- systems where the right way to get out of signal handler is to alter the 212 -- PC value in the machine state or in some other way ask the operating 213 -- system to return here rather than to the original location. 214 215 procedure Raise_From_Controlled_Operation 216 (X : Ada.Exceptions.Exception_Occurrence); 217 pragma No_Return (Raise_From_Controlled_Operation); 218 pragma Export 219 (Ada, Raise_From_Controlled_Operation, 220 "__gnat_raise_from_controlled_operation"); 221 -- Raise Program_Error, providing information about X (an exception raised 222 -- during a controlled operation) in the exception message. 223 224 procedure Reraise_Library_Exception_If_Any; 225 pragma Export 226 (Ada, Reraise_Library_Exception_If_Any, 227 "__gnat_reraise_library_exception_if_any"); 228 -- If there was an exception raised during library-level finalization, 229 -- reraise the exception. 230 231 procedure Reraise_Occurrence_Always (X : Exception_Occurrence); 232 pragma No_Return (Reraise_Occurrence_Always); 233 -- This differs from Raise_Occurrence only in that the caller guarantees 234 -- that for sure the parameter X is not the null occurrence, and that 235 -- therefore this procedure cannot return. The expander uses this routine 236 -- in the translation of a raise statement with no parameter (reraise). 237 238 procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence); 239 pragma No_Return (Reraise_Occurrence_No_Defer); 240 -- Exactly like Reraise_Occurrence, except that abort is not deferred 241 -- before the call and the parameter X is known not to be the null 242 -- occurrence. This is used in generated code when it is known that abort 243 -- is already deferred. 244 245 function Triggered_By_Abort return Boolean; 246 -- Determine whether the current exception (if it exists) is an instance of 247 -- Standard'Abort_Signal. 248 249 ----------------------- 250 -- Polling Interface -- 251 ----------------------- 252 253 -- The GNAT compiler has an option to generate polling calls to the Poll 254 -- routine in this package. Specifying the -gnatP option for a compilation 255 -- causes a call to Ada.Exceptions.Poll to be generated on every subprogram 256 -- entry and on every iteration of a loop, thus avoiding the possibility of 257 -- a case of unbounded time between calls. 258 259 -- This polling interface may be used for instrumentation or debugging 260 -- purposes (e.g. implementing watchpoints in software or in the debugger). 261 262 -- In the GNAT technology itself, this interface is used to implement 263 -- immediate asynchronous transfer of control and immediate abort on 264 -- targets which do not provide for one thread interrupting another. 265 266 -- Note: this used to be in a separate unit called System.Poll, but that 267 -- caused horrible circular elaboration problems between System.Poll and 268 -- Ada.Exceptions. 269 270 procedure Poll; 271 -- Check for asynchronous abort. Note that we do not inline the body. 272 -- This makes the interface more useful for debugging purposes. 273 274 -------------------------- 275 -- Exception_Occurrence -- 276 -------------------------- 277 278 package TBE renames System.Traceback_Entries; 279 280 Max_Tracebacks : constant := 50; 281 -- Maximum number of trace backs stored in exception occurrence 282 283 subtype Tracebacks_Array is TBE.Tracebacks_Array (1 .. Max_Tracebacks); 284 -- Traceback array stored in exception occurrence 285 286 type Exception_Occurrence is record 287 Id : Exception_Id; 288 -- Exception_Identity for this exception occurrence 289 290 Machine_Occurrence : System.Address; 291 -- The underlying machine occurrence. For GCC, this corresponds to the 292 -- _Unwind_Exception structure address. 293 294 Msg_Length : Natural := 0; 295 -- Length of message (zero = no message) 296 297 Msg : String (1 .. Exception_Msg_Max_Length); 298 -- Characters of message 299 300 Exception_Raised : Boolean := False; 301 -- Set to true to indicate that this exception occurrence has actually 302 -- been raised. When an exception occurrence is first created, this is 303 -- set to False, then when it is processed by Raise_Current_Exception, 304 -- it is set to True. If Raise_Current_Exception is used to raise an 305 -- exception for which this flag is already True, then it knows that 306 -- it is dealing with the reraise case (which is useful to distinguish 307 -- for exception tracing purposes). 308 309 Pid : Natural := 0; 310 -- Partition_Id for partition raising exception 311 312 Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0; 313 -- Number of traceback entries stored 314 315 Tracebacks : Tracebacks_Array; 316 -- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks)) 317 end record; 318 319 function "=" (Left, Right : Exception_Occurrence) return Boolean 320 is abstract; 321 -- Don't allow comparison on exception occurrences, we should not need 322 -- this, and it would not work right, because of the Msg and Tracebacks 323 -- fields which have unused entries not copied by Save_Occurrence. 324 325 function Get_Exception_Machine_Occurrence 326 (X : Exception_Occurrence) return System.Address; 327 pragma Export (Ada, Get_Exception_Machine_Occurrence, 328 "__gnat_get_exception_machine_occurrence"); 329 -- Get the machine occurrence corresponding to an exception occurrence. 330 -- It is Null_Address if there is no machine occurrence (in runtimes that 331 -- doesn't use GCC mechanism) or if it has been lost (Save_Occurrence 332 -- doesn't save the machine occurrence). 333 334 function EO_To_String (X : Exception_Occurrence) return String; 335 function String_To_EO (S : String) return Exception_Occurrence; 336 pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String); 337 -- Functions for implementing Exception_Occurrence stream attributes 338 339 Null_Occurrence : constant Exception_Occurrence := ( 340 Id => null, 341 Machine_Occurrence => System.Null_Address, 342 Msg_Length => 0, 343 Msg => (others => ' '), 344 Exception_Raised => False, 345 Pid => 0, 346 Num_Tracebacks => 0, 347 Tracebacks => (others => TBE.Null_TB_Entry)); 348 349end Ada.Exceptions; 350