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