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