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) 1992-2013, 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 both Ada 95 and Ada 2005. 37-- It is used in all situations except for the build of the compiler and 38-- other basic tools. For these latter builds, we use an Ada 95-only version. 39 40-- The reason for this splitting off of a separate version is that bootstrap 41-- compilers often will be used that do not support Ada 2005 features, and 42-- Ada.Exceptions is part of the compiler sources. 43 44pragma Polling (Off); 45-- We must turn polling off for this unit, because otherwise we get 46-- elaboration circularities with ourself. 47 48with System; 49with System.Parameters; 50with System.Standard_Library; 51with System.Traceback_Entries; 52 53package Ada.Exceptions is 54 pragma Preelaborate_05; 55 -- In accordance with Ada 2005 AI-362. 56 57 type Exception_Id is private; 58 pragma Preelaborable_Initialization (Exception_Id); 59 60 Null_Id : constant Exception_Id; 61 62 type Exception_Occurrence is limited private; 63 pragma Preelaborable_Initialization (Exception_Occurrence); 64 65 type Exception_Occurrence_Access is access all Exception_Occurrence; 66 67 Null_Occurrence : constant Exception_Occurrence; 68 69 function Exception_Name (Id : Exception_Id) return String; 70 71 function Exception_Name (X : Exception_Occurrence) return String; 72 73 function Wide_Exception_Name 74 (Id : Exception_Id) return Wide_String; 75 pragma Ada_05 (Wide_Exception_Name); 76 77 function Wide_Exception_Name 78 (X : Exception_Occurrence) return Wide_String; 79 pragma Ada_05 (Wide_Exception_Name); 80 81 function Wide_Wide_Exception_Name 82 (Id : Exception_Id) return Wide_Wide_String; 83 pragma Ada_05 (Wide_Wide_Exception_Name); 84 85 function Wide_Wide_Exception_Name 86 (X : Exception_Occurrence) return Wide_Wide_String; 87 pragma Ada_05 (Wide_Wide_Exception_Name); 88 89 procedure Raise_Exception (E : Exception_Id; Message : String := ""); 90 pragma No_Return (Raise_Exception); 91 -- Note: In accordance with AI-466, CE is raised if E = Null_Id 92 93 function Exception_Message (X : Exception_Occurrence) return String; 94 95 procedure Reraise_Occurrence (X : Exception_Occurrence); 96 -- Note: it would be really nice to give a pragma No_Return for this 97 -- procedure, but it would be wrong, since Reraise_Occurrence does return 98 -- if the argument is the null exception occurrence. See also procedure 99 -- Reraise_Occurrence_Always in the private part of this package. 100 101 function Exception_Identity (X : Exception_Occurrence) return Exception_Id; 102 103 function Exception_Information (X : Exception_Occurrence) return String; 104 -- The format of the exception information is as follows: 105 -- 106 -- exception name (as in Exception_Name) 107 -- message (or a null line if no message) 108 -- PID=nnnn 109 -- 0xyyyyyyyy 0xyyyyyyyy ... 110 -- 111 -- The lines are separated by a ASCII.LF character 112 -- 113 -- The nnnn is the partition Id given as decimal digits 114 -- 115 -- The 0x... line represents traceback program counter locations, 116 -- in order with the first one being the exception location. 117 118 -- Note on ordering: the compiler uses the Save_Occurrence procedure, but 119 -- not the function from Rtsfind, so it is important that the procedure 120 -- come first, since Rtsfind finds the first matching entity. 121 122 procedure Save_Occurrence 123 (Target : out Exception_Occurrence; 124 Source : Exception_Occurrence); 125 126 function Save_Occurrence 127 (Source : Exception_Occurrence) 128 return Exception_Occurrence_Access; 129 130 -- Ada 2005 (AI-438): The language revision introduces the following 131 -- subprograms and attribute definitions. We do not provide them 132 -- explicitly. instead, the corresponding stream attributes are made 133 -- available through a pragma Stream_Convert in the private part. 134 135 -- procedure Read_Exception_Occurrence 136 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 137 -- Item : out Exception_Occurrence); 138 139 -- procedure Write_Exception_Occurrence 140 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 141 -- Item : Exception_Occurrence); 142 143 -- for Exception_Occurrence'Read use Read_Exception_Occurrence; 144 -- for Exception_Occurrence'Write use Write_Exception_Occurrence; 145 146private 147 package SSL renames System.Standard_Library; 148 package SP renames System.Parameters; 149 150 subtype EOA is Exception_Occurrence_Access; 151 152 Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length; 153 154 ------------------ 155 -- Exception_Id -- 156 ------------------ 157 158 subtype Code_Loc is System.Address; 159 -- Code location used in building exception tables and for call addresses 160 -- when propagating an exception. Values of this type are created by using 161 -- Label'Address or extracted from machine states using Get_Code_Loc. 162 163 Null_Loc : constant Code_Loc := System.Null_Address; 164 -- Null code location, used to flag outer level frame 165 166 type Exception_Id is new SSL.Exception_Data_Ptr; 167 168 function EId_To_String (X : Exception_Id) return String; 169 function String_To_EId (S : String) return Exception_Id; 170 pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String); 171 -- Functions for implementing Exception_Id stream attributes 172 173 Null_Id : constant Exception_Id := null; 174 175 ------------------------- 176 -- Private Subprograms -- 177 ------------------------- 178 179 function Current_Target_Exception return Exception_Occurrence; 180 pragma Export 181 (Ada, Current_Target_Exception, 182 "__gnat_current_target_exception"); 183 -- This routine should return the current raised exception on targets which 184 -- have built-in exception handling such as the Java Virtual Machine. For 185 -- other targets this routine is simply ignored. Currently, only JGNAT 186 -- uses this. See 4jexcept.ads for details. The pragma Export allows this 187 -- routine to be accessed elsewhere in the run-time, even though it is in 188 -- the private part of this package (it is not allowed to be in the visible 189 -- part, since this is set by the reference manual). 190 191 function Exception_Name_Simple (X : Exception_Occurrence) return String; 192 -- Like Exception_Name, but returns the simple non-qualified name of the 193 -- exception. This is used to implement the Exception_Name function in 194 -- Current_Exceptions (the DEC compatible unit). It is called from the 195 -- compiler generated code (using Rtsfind, which does not respect the 196 -- private barrier, so we can place this function in the private part 197 -- where the compiler can find it, but the spec is unchanged.) 198 199 procedure Raise_Exception_Always (E : Exception_Id; Message : String := ""); 200 pragma No_Return (Raise_Exception_Always); 201 pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception"); 202 -- This differs from Raise_Exception only in that the caller has determined 203 -- that for sure the parameter E is not null, and that therefore no check 204 -- for Null_Id is required. The expander converts Raise_Exception calls to 205 -- Raise_Exception_Always if it can determine this is the case. The Export 206 -- allows this routine to be accessed from Pure units. 207 208 procedure Raise_From_Signal_Handler 209 (E : Exception_Id; 210 M : System.Address); 211 pragma Export 212 (Ada, Raise_From_Signal_Handler, 213 "ada__exceptions__raise_from_signal_handler"); 214 pragma No_Return (Raise_From_Signal_Handler); 215 -- This routine is used to raise an exception from a signal handler. The 216 -- signal handler has already stored the machine state (i.e. the state that 217 -- corresponds to the location at which the signal was raised). E is the 218 -- Exception_Id specifying what exception is being raised, and M is a 219 -- pointer to a null-terminated string which is the message to be raised. 220 -- Note that this routine never returns, so it is permissible to simply 221 -- jump to this routine, rather than call it. This may be appropriate for 222 -- systems where the right way to get out of signal handler is to alter the 223 -- PC value in the machine state or in some other way ask the operating 224 -- system to return here rather than to the original location. 225 226 procedure Raise_From_Controlled_Operation 227 (X : Ada.Exceptions.Exception_Occurrence); 228 pragma No_Return (Raise_From_Controlled_Operation); 229 pragma Export 230 (Ada, Raise_From_Controlled_Operation, 231 "__gnat_raise_from_controlled_operation"); 232 -- Raise Program_Error, providing information about X (an exception raised 233 -- during a controlled operation) in the exception message. 234 235 procedure Reraise_Library_Exception_If_Any; 236 pragma Export 237 (Ada, Reraise_Library_Exception_If_Any, 238 "__gnat_reraise_library_exception_if_any"); 239 -- If there was an exception raised during library-level finalization, 240 -- reraise the exception. 241 242 procedure Reraise_Occurrence_Always (X : Exception_Occurrence); 243 pragma No_Return (Reraise_Occurrence_Always); 244 -- This differs from Raise_Occurrence only in that the caller guarantees 245 -- that for sure the parameter X is not the null occurrence, and that 246 -- therefore this procedure cannot return. The expander uses this routine 247 -- in the translation of a raise statement with no parameter (reraise). 248 249 procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence); 250 pragma No_Return (Reraise_Occurrence_No_Defer); 251 -- Exactly like Reraise_Occurrence, except that abort is not deferred 252 -- before the call and the parameter X is known not to be the null 253 -- occurrence. This is used in generated code when it is known that abort 254 -- is already deferred. 255 256 function Triggered_By_Abort return Boolean; 257 -- Determine whether the current exception (if it exists) is an instance of 258 -- Standard'Abort_Signal. 259 260 ----------------------- 261 -- Polling Interface -- 262 ----------------------- 263 264 -- The GNAT compiler has an option to generate polling calls to the Poll 265 -- routine in this package. Specifying the -gnatP option for a compilation 266 -- causes a call to Ada.Exceptions.Poll to be generated on every subprogram 267 -- entry and on every iteration of a loop, thus avoiding the possibility of 268 -- a case of unbounded time between calls. 269 270 -- This polling interface may be used for instrumentation or debugging 271 -- purposes (e.g. implementing watchpoints in software or in the debugger). 272 273 -- In the GNAT technology itself, this interface is used to implement 274 -- immediate asynchronous transfer of control and immediate abort on 275 -- targets which do not provide for one thread interrupting another. 276 277 -- Note: this used to be in a separate unit called System.Poll, but that 278 -- caused horrible circular elaboration problems between System.Poll and 279 -- Ada.Exceptions. 280 281 procedure Poll; 282 -- Check for asynchronous abort. Note that we do not inline the body. 283 -- This makes the interface more useful for debugging purposes. 284 285 -------------------------- 286 -- Exception_Occurrence -- 287 -------------------------- 288 289 package TBE renames System.Traceback_Entries; 290 291 Max_Tracebacks : constant := 50; 292 -- Maximum number of trace backs stored in exception occurrence 293 294 type Tracebacks_Array is array (1 .. Max_Tracebacks) of TBE.Traceback_Entry; 295 -- Traceback array stored in exception occurrence 296 297 type Exception_Occurrence is record 298 Id : Exception_Id; 299 -- Exception_Identity for this exception occurrence 300 301 Machine_Occurrence : System.Address; 302 -- The underlying machine occurrence. For GCC, this corresponds to the 303 -- _Unwind_Exception structure address. 304 305 Msg_Length : Natural := 0; 306 -- Length of message (zero = no message) 307 308 Msg : String (1 .. Exception_Msg_Max_Length); 309 -- Characters of message 310 311 Exception_Raised : Boolean := False; 312 -- Set to true to indicate that this exception occurrence has actually 313 -- been raised. When an exception occurrence is first created, this is 314 -- set to False, then when it is processed by Raise_Current_Exception, 315 -- it is set to True. If Raise_Current_Exception is used to raise an 316 -- exception for which this flag is already True, then it knows that 317 -- it is dealing with the reraise case (which is useful to distinguish 318 -- for exception tracing purposes). 319 320 Pid : Natural := 0; 321 -- Partition_Id for partition raising exception 322 323 Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0; 324 -- Number of traceback entries stored 325 326 Tracebacks : Tracebacks_Array; 327 -- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks)) 328 end record; 329 330 function "=" (Left, Right : Exception_Occurrence) return Boolean 331 is abstract; 332 -- Don't allow comparison on exception occurrences, we should not need 333 -- this, and it would not work right, because of the Msg and Tracebacks 334 -- fields which have unused entries not copied by Save_Occurrence. 335 336 function Get_Exception_Machine_Occurrence 337 (X : Exception_Occurrence) return System.Address; 338 pragma Export (Ada, Get_Exception_Machine_Occurrence, 339 "__gnat_get_exception_machine_occurrence"); 340 -- Get the machine occurrence corresponding to an exception occurrence. 341 -- It is Null_Address if there is no machine occurrence (in runtimes that 342 -- doesn't use GCC mechanism) or if it has been lost (Save_Occurrence 343 -- doesn't save the machine occurrence). 344 345 function EO_To_String (X : Exception_Occurrence) return String; 346 function String_To_EO (S : String) return Exception_Occurrence; 347 pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String); 348 -- Functions for implementing Exception_Occurrence stream attributes 349 350 Null_Occurrence : constant Exception_Occurrence := ( 351 Id => null, 352 Machine_Occurrence => System.Null_Address, 353 Msg_Length => 0, 354 Msg => (others => ' '), 355 Exception_Raised => False, 356 Pid => 0, 357 Num_Tracebacks => 0, 358 Tracebacks => (others => TBE.Null_TB_Entry)); 359 360end Ada.Exceptions; 361