1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger. 2 3 Copyright (C) 1986-2024 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #ifndef COMMON_COMMON_EXCEPTIONS_H 21 #define COMMON_COMMON_EXCEPTIONS_H 22 23 #include <setjmp.h> 24 #include <new> 25 #include <memory> 26 #include <string> 27 #include <functional> 28 29 #include "gdbsupport/underlying.h" 30 31 /* Reasons for calling throw_exceptions(). NOTE: all reason values 32 must be different from zero. enum value 0 is reserved for internal 33 use as the return value from an initial setjmp(). */ 34 35 enum return_reason 36 { 37 /* SIGTERM sent to GDB. */ 38 RETURN_FORCED_QUIT = -3, 39 /* User interrupt. */ 40 RETURN_QUIT = -2, 41 /* Any other error. */ 42 RETURN_ERROR 43 }; 44 45 #define RETURN_MASK(reason) (1 << (int)(-reason)) 46 47 typedef enum 48 { 49 RETURN_MASK_FORCED_QUIT = RETURN_MASK (RETURN_FORCED_QUIT), 50 RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT), 51 RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR), 52 RETURN_MASK_ALL = (RETURN_MASK_FORCED_QUIT | RETURN_MASK_QUIT | RETURN_MASK_ERROR) 53 } return_mask; 54 55 /* Describe all exceptions. */ 56 57 enum errors { 58 GDB_NO_ERROR, 59 60 /* Any generic error, the corresponding text is in 61 exception.message. */ 62 GENERIC_ERROR, 63 64 /* Something requested was not found. */ 65 NOT_FOUND_ERROR, 66 67 /* Thread library lacks support necessary for finding thread local 68 storage. */ 69 TLS_NO_LIBRARY_SUPPORT_ERROR, 70 71 /* Load module not found while attempting to find thread local storage. */ 72 TLS_LOAD_MODULE_NOT_FOUND_ERROR, 73 74 /* Thread local storage has not been allocated yet. */ 75 TLS_NOT_ALLOCATED_YET_ERROR, 76 77 /* Something else went wrong while attempting to find thread local 78 storage. The ``struct gdb_exception'' message field provides 79 more detail. */ 80 TLS_GENERIC_ERROR, 81 82 /* Problem parsing an XML document. */ 83 XML_PARSE_ERROR, 84 85 /* Error accessing memory. */ 86 MEMORY_ERROR, 87 88 /* Value not available. E.g., a register was not collected in a 89 traceframe. */ 90 NOT_AVAILABLE_ERROR, 91 92 /* Value was optimized out. Note: if the value was a register, this 93 means the register was not saved in the frame. */ 94 OPTIMIZED_OUT_ERROR, 95 96 /* DW_OP_entry_value resolving failed. */ 97 NO_ENTRY_VALUE_ERROR, 98 99 /* Target throwing an error has been closed. Current command should be 100 aborted as the inferior state is no longer valid. */ 101 TARGET_CLOSE_ERROR, 102 103 /* An undefined command was executed. */ 104 UNDEFINED_COMMAND_ERROR, 105 106 /* Requested feature, method, mechanism, etc. is not supported. */ 107 NOT_SUPPORTED_ERROR, 108 109 /* The number of candidates generated during line completion has 110 reached the user's specified limit. This isn't an error, this exception 111 is used to halt searching for more completions, but for consistency 112 "_ERROR" is appended to the name. */ 113 MAX_COMPLETIONS_REACHED_ERROR, 114 115 /* Add more errors here. */ 116 NR_ERRORS 117 }; 118 119 struct gdb_exception 120 { 121 gdb_exception () 122 : reason ((enum return_reason) 0), 123 error (GDB_NO_ERROR) 124 { 125 } 126 127 gdb_exception (enum return_reason r, enum errors e) 128 : reason (r), 129 error (e) 130 { 131 } 132 133 gdb_exception (enum return_reason r, enum errors e, 134 const char *fmt, va_list ap) 135 ATTRIBUTE_PRINTF (4, 0) 136 : reason (r), 137 error (e), 138 message (std::make_shared<std::string> (string_vprintf (fmt, ap))) 139 { 140 } 141 142 /* The move constructor exists so that we can mark it "noexcept", 143 which is a good practice for any sort of exception object. */ 144 explicit gdb_exception (gdb_exception &&other) noexcept = default; 145 146 /* The copy constructor exists so that we can mark it "noexcept", 147 which is a good practice for any sort of exception object. */ 148 gdb_exception (const gdb_exception &other) noexcept 149 : reason (other.reason), 150 error (other.error), 151 message (other.message) 152 { 153 } 154 155 /* The assignment operator exists so that we can mark it "noexcept", 156 which is a good practice for any sort of exception object. */ 157 gdb_exception &operator= (const gdb_exception &other) noexcept 158 { 159 reason = other.reason; 160 error = other.error; 161 message = other.message; 162 return *this; 163 } 164 165 gdb_exception &operator= (gdb_exception &&other) noexcept = default; 166 167 /* Return the contents of the exception message, as a C string. The 168 string remains owned by the exception object. */ 169 const char *what () const noexcept 170 { 171 return message->c_str (); 172 } 173 174 /* Compare two exceptions. */ 175 bool operator== (const gdb_exception &other) const 176 { 177 const char *msg1 = message == nullptr ? "" : what (); 178 const char *msg2 = other.message == nullptr ? "" : other.what (); 179 180 return (reason == other.reason 181 && error == other.error 182 && strcmp (msg1, msg2) == 0); 183 } 184 185 /* Compare two exceptions. */ 186 bool operator!= (const gdb_exception &other) const 187 { 188 return !(*this == other); 189 } 190 191 enum return_reason reason; 192 enum errors error; 193 std::shared_ptr<std::string> message; 194 }; 195 196 namespace std 197 { 198 199 /* Specialization of std::hash for gdb_exception. */ 200 template<> 201 struct hash<gdb_exception> 202 { 203 size_t operator() (const gdb_exception &exc) const 204 { 205 size_t result = to_underlying (exc.reason) + to_underlying (exc.error); 206 if (exc.message != nullptr) 207 result += std::hash<std::string> {} (*exc.message); 208 return result; 209 } 210 }; 211 212 } 213 214 /* Functions to drive the sjlj-based exceptions state machine. Though 215 declared here by necessity, these functions should be considered 216 internal to the exceptions subsystem and not used other than via 217 the TRY/CATCH (or TRY_SJLJ/CATCH_SJLJ) macros defined below. */ 218 219 extern jmp_buf *exceptions_state_mc_init (void); 220 extern int exceptions_state_mc_action_iter (void); 221 extern int exceptions_state_mc_action_iter_1 (void); 222 extern int exceptions_state_mc_catch (struct gdb_exception *, int); 223 224 /* Macro to wrap up standard try/catch behavior. 225 226 The double loop lets us correctly handle code "break"ing out of the 227 try catch block. (It works as the "break" only exits the inner 228 "while" loop, the outer for loop detects this handling it 229 correctly.) Of course "return" and "goto" are not so lucky. 230 231 For instance: 232 233 *INDENT-OFF* 234 235 TRY_SJLJ 236 { 237 } 238 CATCH_SJLJ (e, RETURN_MASK_ERROR) 239 { 240 switch (e.reason) 241 { 242 case RETURN_ERROR: ... 243 } 244 } 245 END_CATCH_SJLJ 246 247 The SJLJ variants are needed in some cases where gdb exceptions 248 need to cross third-party library code compiled without exceptions 249 support (e.g., readline). */ 250 251 #define TRY_SJLJ \ 252 { \ 253 jmp_buf *buf = \ 254 exceptions_state_mc_init (); \ 255 setjmp (*buf); \ 256 } \ 257 while (exceptions_state_mc_action_iter ()) \ 258 while (exceptions_state_mc_action_iter_1 ()) 259 260 #define CATCH_SJLJ(EXCEPTION, MASK) \ 261 { \ 262 struct gdb_exception EXCEPTION; \ 263 if (exceptions_state_mc_catch (&(EXCEPTION), MASK)) 264 265 #define END_CATCH_SJLJ \ 266 } 267 268 /* The exception types client code may catch. They're just shims 269 around gdb_exception that add nothing but type info. Which is used 270 is selected depending on the MASK argument passed to CATCH. */ 271 272 struct gdb_exception_error : public gdb_exception 273 { 274 gdb_exception_error (enum errors e, const char *fmt, va_list ap) 275 ATTRIBUTE_PRINTF (3, 0) 276 : gdb_exception (RETURN_ERROR, e, fmt, ap) 277 { 278 } 279 280 explicit gdb_exception_error (gdb_exception &&ex) noexcept 281 : gdb_exception (std::move (ex)) 282 { 283 gdb_assert (ex.reason == RETURN_ERROR); 284 } 285 }; 286 287 struct gdb_exception_quit : public gdb_exception 288 { 289 gdb_exception_quit (const char *fmt, va_list ap) 290 ATTRIBUTE_PRINTF (2, 0) 291 : gdb_exception (RETURN_QUIT, GDB_NO_ERROR, fmt, ap) 292 { 293 } 294 295 explicit gdb_exception_quit (gdb_exception &&ex) noexcept 296 : gdb_exception (std::move (ex)) 297 { 298 gdb_assert (ex.reason == RETURN_QUIT); 299 } 300 }; 301 302 struct gdb_exception_forced_quit : public gdb_exception 303 { 304 gdb_exception_forced_quit (const char *fmt, va_list ap) 305 ATTRIBUTE_PRINTF (2, 0) 306 : gdb_exception (RETURN_FORCED_QUIT, GDB_NO_ERROR, fmt, ap) 307 { 308 } 309 310 explicit gdb_exception_forced_quit (gdb_exception &&ex) noexcept 311 : gdb_exception (std::move (ex)) 312 { 313 gdb_assert (ex.reason == RETURN_FORCED_QUIT); 314 } 315 }; 316 317 /* An exception type that inherits from both std::bad_alloc and a gdb 318 exception. This is necessary because operator new can only throw 319 std::bad_alloc, and OTOH, we want exceptions thrown due to memory 320 allocation error to be caught by all the CATCH/RETURN_MASK_ALL 321 spread around the codebase. */ 322 323 struct gdb_quit_bad_alloc 324 : public gdb_exception_quit, 325 public std::bad_alloc 326 { 327 explicit gdb_quit_bad_alloc (gdb_exception &&ex) noexcept 328 : gdb_exception_quit (std::move (ex)), 329 std::bad_alloc () 330 { 331 } 332 }; 333 334 /* *INDENT-ON* */ 335 336 /* Throw an exception (as described by "struct gdb_exception"), 337 landing in the inner most containing exception handler established 338 using TRY/CATCH. */ 339 extern void throw_exception (gdb_exception &&exception) 340 ATTRIBUTE_NORETURN; 341 342 /* Throw an exception by executing a LONG JUMP to the inner most 343 containing exception handler established using TRY_SJLJ. Necessary 344 in some cases where we need to throw GDB exceptions across 345 third-party library code (e.g., readline). */ 346 extern void throw_exception_sjlj (const struct gdb_exception &exception) 347 ATTRIBUTE_NORETURN; 348 349 /* Convenience wrappers around throw_exception that throw GDB 350 errors. */ 351 extern void throw_verror (enum errors, const char *fmt, va_list ap) 352 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0); 353 extern void throw_vquit (const char *fmt, va_list ap) 354 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0); 355 extern void throw_error (enum errors error, const char *fmt, ...) 356 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3); 357 extern void throw_quit (const char *fmt, ...) 358 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2); 359 extern void throw_forced_quit (const char *fmt, ...) 360 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2); 361 362 #endif /* COMMON_COMMON_EXCEPTIONS_H */ 363