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) 1992-2012, 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 Warnings (Off); 55 pragma Preelaborate_05; 56 pragma Warnings (On); 57 -- In accordance with Ada 2005 AI-362. The warnings pragmas are so that we 58 -- can compile this using older compiler versions, which will ignore the 59 -- pragma, which is fine for the bootstrap. 60 61 type Exception_Id is private; 62 pragma Preelaborable_Initialization (Exception_Id); 63 64 Null_Id : constant Exception_Id; 65 66 type Exception_Occurrence is limited private; 67 pragma Preelaborable_Initialization (Exception_Occurrence); 68 69 type Exception_Occurrence_Access is access all Exception_Occurrence; 70 71 Null_Occurrence : constant Exception_Occurrence; 72 73 function Exception_Name (Id : Exception_Id) return String; 74 75 function Exception_Name (X : Exception_Occurrence) return String; 76 77 function Wide_Exception_Name 78 (Id : Exception_Id) return Wide_String; 79 pragma Ada_05 (Wide_Exception_Name); 80 81 function Wide_Exception_Name 82 (X : Exception_Occurrence) return Wide_String; 83 pragma Ada_05 (Wide_Exception_Name); 84 85 function Wide_Wide_Exception_Name 86 (Id : Exception_Id) return Wide_Wide_String; 87 pragma Ada_05 (Wide_Wide_Exception_Name); 88 89 function Wide_Wide_Exception_Name 90 (X : Exception_Occurrence) return Wide_Wide_String; 91 pragma Ada_05 (Wide_Wide_Exception_Name); 92 93 procedure Raise_Exception (E : Exception_Id; Message : String := ""); 94 pragma No_Return (Raise_Exception); 95 -- Note: In accordance with AI-466, CE is raised if E = Null_Id 96 97 function Exception_Message (X : Exception_Occurrence) return String; 98 99 procedure Reraise_Occurrence (X : Exception_Occurrence); 100 -- Note: it would be really nice to give a pragma No_Return for this 101 -- procedure, but it would be wrong, since Reraise_Occurrence does return 102 -- if the argument is the null exception occurrence. See also procedure 103 -- Reraise_Occurrence_Always in the private part of this package. 104 105 function Exception_Identity (X : Exception_Occurrence) return Exception_Id; 106 107 function Exception_Information (X : Exception_Occurrence) return String; 108 -- The format of the exception information is as follows: 109 -- 110 -- exception name (as in Exception_Name) 111 -- message (or a null line if no message) 112 -- PID=nnnn 113 -- 0xyyyyyyyy 0xyyyyyyyy ... 114 -- 115 -- The lines are separated by a ASCII.LF character 116 -- 117 -- The nnnn is the partition Id given as decimal digits 118 -- 119 -- The 0x... line represents traceback program counter locations, 120 -- in order with the first one being the exception location. 121 122 -- Note on ordering: the compiler uses the Save_Occurrence procedure, but 123 -- not the function from Rtsfind, so it is important that the procedure 124 -- come first, since Rtsfind finds the first matching entity. 125 126 procedure Save_Occurrence 127 (Target : out Exception_Occurrence; 128 Source : Exception_Occurrence); 129 130 function Save_Occurrence 131 (Source : Exception_Occurrence) 132 return Exception_Occurrence_Access; 133 134 -- Ada 2005 (AI-438): The language revision introduces the following 135 -- subprograms and attribute definitions. We do not provide them 136 -- explicitly. instead, the corresponding stream attributes are made 137 -- available through a pragma Stream_Convert in the private part. 138 139 -- procedure Read_Exception_Occurrence 140 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 141 -- Item : out Exception_Occurrence); 142 143 -- procedure Write_Exception_Occurrence 144 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class; 145 -- Item : Exception_Occurrence); 146 147 -- for Exception_Occurrence'Read use Read_Exception_Occurrence; 148 -- for Exception_Occurrence'Write use Write_Exception_Occurrence; 149 150private 151 package SSL renames System.Standard_Library; 152 package SP renames System.Parameters; 153 154 subtype EOA is Exception_Occurrence_Access; 155 156 Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length; 157 158 ------------------ 159 -- Exception_Id -- 160 ------------------ 161 162 subtype Code_Loc is System.Address; 163 -- Code location used in building exception tables and for call addresses 164 -- when propagating an exception. Values of this type are created by using 165 -- Label'Address or extracted from machine states using Get_Code_Loc. 166 167 Null_Loc : constant Code_Loc := System.Null_Address; 168 -- Null code location, used to flag outer level frame 169 170 type Exception_Id is new SSL.Exception_Data_Ptr; 171 172 function EId_To_String (X : Exception_Id) return String; 173 function String_To_EId (S : String) return Exception_Id; 174 pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String); 175 -- Functions for implementing Exception_Id stream attributes 176 177 Null_Id : constant Exception_Id := null; 178 179 ------------------------- 180 -- Private Subprograms -- 181 ------------------------- 182 183 function Current_Target_Exception return Exception_Occurrence; 184 pragma Export 185 (Ada, Current_Target_Exception, 186 "__gnat_current_target_exception"); 187 -- This routine should return the current raised exception on targets which 188 -- have built-in exception handling such as the Java Virtual Machine. For 189 -- other targets this routine is simply ignored. Currently, only JGNAT 190 -- uses this. See 4jexcept.ads for details. The pragma Export allows this 191 -- routine to be accessed elsewhere in the run-time, even though it is in 192 -- the private part of this package (it is not allowed to be in the visible 193 -- part, since this is set by the reference manual). 194 195 function Exception_Name_Simple (X : Exception_Occurrence) return String; 196 -- Like Exception_Name, but returns the simple non-qualified name of the 197 -- exception. This is used to implement the Exception_Name function in 198 -- Current_Exceptions (the DEC compatible unit). It is called from the 199 -- compiler generated code (using Rtsfind, which does not respect the 200 -- private barrier, so we can place this function in the private part 201 -- where the compiler can find it, but the spec is unchanged.) 202 203 procedure Raise_Exception_Always (E : Exception_Id; Message : String := ""); 204 pragma No_Return (Raise_Exception_Always); 205 pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception"); 206 -- This differs from Raise_Exception only in that the caller has determined 207 -- that for sure the parameter E is not null, and that therefore no check 208 -- for Null_Id is required. The expander converts Raise_Exception calls to 209 -- Raise_Exception_Always if it can determine this is the case. The Export 210 -- allows this routine to be accessed from Pure units. 211 212 procedure Raise_From_Signal_Handler 213 (E : Exception_Id; 214 M : System.Address); 215 pragma Export 216 (Ada, Raise_From_Signal_Handler, 217 "ada__exceptions__raise_from_signal_handler"); 218 pragma No_Return (Raise_From_Signal_Handler); 219 -- This routine is used to raise an exception from a signal handler. The 220 -- signal handler has already stored the machine state (i.e. the state that 221 -- corresponds to the location at which the signal was raised). E is the 222 -- Exception_Id specifying what exception is being raised, and M is a 223 -- pointer to a null-terminated string which is the message to be raised. 224 -- Note that this routine never returns, so it is permissible to simply 225 -- jump to this routine, rather than call it. This may be appropriate for 226 -- systems where the right way to get out of signal handler is to alter the 227 -- PC value in the machine state or in some other way ask the operating 228 -- system to return here rather than to the original location. 229 230 procedure Raise_From_Controlled_Operation 231 (X : Ada.Exceptions.Exception_Occurrence); 232 pragma No_Return (Raise_From_Controlled_Operation); 233 pragma Export 234 (Ada, Raise_From_Controlled_Operation, 235 "__gnat_raise_from_controlled_operation"); 236 -- Raise Program_Error, providing information about X (an exception raised 237 -- during a controlled operation) in the exception message. 238 239 procedure Reraise_Library_Exception_If_Any; 240 pragma Export 241 (Ada, Reraise_Library_Exception_If_Any, 242 "__gnat_reraise_library_exception_if_any"); 243 -- If there was an exception raised during library-level finalization, 244 -- reraise the exception. 245 246 procedure Reraise_Occurrence_Always (X : Exception_Occurrence); 247 pragma No_Return (Reraise_Occurrence_Always); 248 -- This differs from Raise_Occurrence only in that the caller guarantees 249 -- that for sure the parameter X is not the null occurrence, and that 250 -- therefore this procedure cannot return. The expander uses this routine 251 -- in the translation of a raise statement with no parameter (reraise). 252 253 procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence); 254 pragma No_Return (Reraise_Occurrence_No_Defer); 255 -- Exactly like Reraise_Occurrence, except that abort is not deferred 256 -- before the call and the parameter X is known not to be the null 257 -- occurrence. This is used in generated code when it is known that abort 258 -- is already deferred. 259 260 function Triggered_By_Abort return Boolean; 261 -- Determine whether the current exception (if it exists) is an instance of 262 -- Standard'Abort_Signal. 263 264 ----------------------- 265 -- Polling Interface -- 266 ----------------------- 267 268 -- The GNAT compiler has an option to generate polling calls to the Poll 269 -- routine in this package. Specifying the -gnatP option for a compilation 270 -- causes a call to Ada.Exceptions.Poll to be generated on every subprogram 271 -- entry and on every iteration of a loop, thus avoiding the possibility of 272 -- a case of unbounded time between calls. 273 274 -- This polling interface may be used for instrumentation or debugging 275 -- purposes (e.g. implementing watchpoints in software or in the debugger). 276 277 -- In the GNAT technology itself, this interface is used to implement 278 -- immediate asynchronous transfer of control and immediate abort on 279 -- targets which do not provide for one thread interrupting another. 280 281 -- Note: this used to be in a separate unit called System.Poll, but that 282 -- caused horrible circular elaboration problems between System.Poll and 283 -- Ada.Exceptions. One way of solving such circularities is unification! 284 285 procedure Poll; 286 -- Check for asynchronous abort. Note that we do not inline the body. 287 -- This makes the interface more useful for debugging purposes. 288 289 -------------------------- 290 -- Exception_Occurrence -- 291 -------------------------- 292 293 package TBE renames System.Traceback_Entries; 294 295 Max_Tracebacks : constant := 50; 296 -- Maximum number of trace backs stored in exception occurrence 297 298 type Tracebacks_Array is array (1 .. Max_Tracebacks) of TBE.Traceback_Entry; 299 -- Traceback array stored in exception occurrence 300 301 type Exception_Occurrence is record 302 Id : Exception_Id; 303 -- Exception_Identity for this exception occurrence 304 305 Machine_Occurrence : System.Address; 306 -- The underlying machine occurrence. For GCC, this corresponds to the 307 -- _Unwind_Exception structure address. 308 309 Msg_Length : Natural := 0; 310 -- Length of message (zero = no message) 311 312 Msg : String (1 .. Exception_Msg_Max_Length); 313 -- Characters of message 314 315 Exception_Raised : Boolean := False; 316 -- Set to true to indicate that this exception occurrence has actually 317 -- been raised. When an exception occurrence is first created, this is 318 -- set to False, then when it is processed by Raise_Current_Exception, 319 -- it is set to True. If Raise_Current_Exception is used to raise an 320 -- exception for which this flag is already True, then it knows that 321 -- it is dealing with the reraise case (which is useful to distinguish 322 -- for exception tracing purposes). 323 324 Pid : Natural := 0; 325 -- Partition_Id for partition raising exception 326 327 Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0; 328 -- Number of traceback entries stored 329 330 Tracebacks : Tracebacks_Array; 331 -- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks)) 332 end record; 333 334 function "=" (Left, Right : Exception_Occurrence) return Boolean 335 is abstract; 336 -- Don't allow comparison on exception occurrences, we should not need 337 -- this, and it would not work right, because of the Msg and Tracebacks 338 -- fields which have unused entries not copied by Save_Occurrence. 339 340 function EO_To_String (X : Exception_Occurrence) return String; 341 function String_To_EO (S : String) return Exception_Occurrence; 342 pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String); 343 -- Functions for implementing Exception_Occurrence stream attributes 344 345 Null_Occurrence : constant Exception_Occurrence := ( 346 Id => null, 347 Machine_Occurrence => System.Null_Address, 348 Msg_Length => 0, 349 Msg => (others => ' '), 350 Exception_Raised => False, 351 Pid => 0, 352 Num_Tracebacks => 0, 353 Tracebacks => (others => TBE.Null_TB_Entry)); 354 355end Ada.Exceptions; 356