| 1 | /* Exception (throw catch) mechanism, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright (C) 1986-2015 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 | #include "common-defs.h" |
| 21 | #include "common-exceptions.h" |
| 22 | |
| 23 | const struct gdb_exception exception_none = { 0, GDB_NO_ERROR, NULL }; |
| 24 | |
| 25 | #ifndef __cplusplus |
| 26 | |
| 27 | /* Possible catcher states. */ |
| 28 | enum catcher_state { |
| 29 | /* Initial state, a new catcher has just been created. */ |
| 30 | CATCHER_CREATED, |
| 31 | /* The catch code is running. */ |
| 32 | CATCHER_RUNNING, |
| 33 | CATCHER_RUNNING_1, |
| 34 | /* The catch code threw an exception. */ |
| 35 | CATCHER_ABORTING |
| 36 | }; |
| 37 | |
| 38 | /* Possible catcher actions. */ |
| 39 | enum catcher_action { |
| 40 | CATCH_ITER, |
| 41 | CATCH_ITER_1, |
| 42 | CATCH_THROWING |
| 43 | }; |
| 44 | |
| 45 | struct catcher |
| 46 | { |
| 47 | enum catcher_state state; |
| 48 | /* Jump buffer pointing back at the exception handler. */ |
| 49 | SIGJMP_BUF buf; |
| 50 | /* Status buffer belonging to the exception handler. */ |
| 51 | struct gdb_exception exception; |
| 52 | struct cleanup *saved_cleanup_chain; |
| 53 | /* Back link. */ |
| 54 | struct catcher *prev; |
| 55 | }; |
| 56 | |
| 57 | /* Where to go for throw_exception(). */ |
| 58 | static struct catcher *current_catcher; |
| 59 | |
| 60 | /* Return length of current_catcher list. */ |
| 61 | |
| 62 | static int |
| 63 | catcher_list_size (void) |
| 64 | { |
| 65 | int size; |
| 66 | struct catcher *catcher; |
| 67 | |
| 68 | for (size = 0, catcher = current_catcher; |
| 69 | catcher != NULL; |
| 70 | catcher = catcher->prev) |
| 71 | ++size; |
| 72 | |
| 73 | return size; |
| 74 | } |
| 75 | |
| 76 | SIGJMP_BUF * |
| 77 | exceptions_state_mc_init (void) |
| 78 | { |
| 79 | struct catcher *new_catcher = XCNEW (struct catcher); |
| 80 | |
| 81 | /* Start with no exception. */ |
| 82 | new_catcher->exception = exception_none; |
| 83 | |
| 84 | /* Prevent error/quit during FUNC from calling cleanups established |
| 85 | prior to here. */ |
| 86 | new_catcher->saved_cleanup_chain = save_cleanups (); |
| 87 | |
| 88 | /* Push this new catcher on the top. */ |
| 89 | new_catcher->prev = current_catcher; |
| 90 | current_catcher = new_catcher; |
| 91 | new_catcher->state = CATCHER_CREATED; |
| 92 | |
| 93 | return &new_catcher->buf; |
| 94 | } |
| 95 | |
| 96 | static void |
| 97 | catcher_pop (void) |
| 98 | { |
| 99 | struct catcher *old_catcher = current_catcher; |
| 100 | |
| 101 | current_catcher = old_catcher->prev; |
| 102 | |
| 103 | /* Restore the cleanup chain, the error/quit messages, and the uiout |
| 104 | builder, to their original states. */ |
| 105 | |
| 106 | restore_cleanups (old_catcher->saved_cleanup_chain); |
| 107 | |
| 108 | xfree (old_catcher); |
| 109 | } |
| 110 | |
| 111 | /* Catcher state machine. Returns non-zero if the m/c should be run |
| 112 | again, zero if it should abort. */ |
| 113 | |
| 114 | static int |
| 115 | exceptions_state_mc (enum catcher_action action) |
| 116 | { |
| 117 | switch (current_catcher->state) |
| 118 | { |
| 119 | case CATCHER_CREATED: |
| 120 | switch (action) |
| 121 | { |
| 122 | case CATCH_ITER: |
| 123 | /* Allow the code to run the catcher. */ |
| 124 | current_catcher->state = CATCHER_RUNNING; |
| 125 | return 1; |
| 126 | default: |
| 127 | internal_error (__FILE__, __LINE__, _("bad state")); |
| 128 | } |
| 129 | case CATCHER_RUNNING: |
| 130 | switch (action) |
| 131 | { |
| 132 | case CATCH_ITER: |
| 133 | /* No error/quit has occured. */ |
| 134 | return 0; |
| 135 | case CATCH_ITER_1: |
| 136 | current_catcher->state = CATCHER_RUNNING_1; |
| 137 | return 1; |
| 138 | case CATCH_THROWING: |
| 139 | current_catcher->state = CATCHER_ABORTING; |
| 140 | /* See also throw_exception. */ |
| 141 | return 1; |
| 142 | default: |
| 143 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 144 | } |
| 145 | case CATCHER_RUNNING_1: |
| 146 | switch (action) |
| 147 | { |
| 148 | case CATCH_ITER: |
| 149 | /* The did a "break" from the inner while loop. */ |
| 150 | return 0; |
| 151 | case CATCH_ITER_1: |
| 152 | current_catcher->state = CATCHER_RUNNING; |
| 153 | return 0; |
| 154 | case CATCH_THROWING: |
| 155 | current_catcher->state = CATCHER_ABORTING; |
| 156 | /* See also throw_exception. */ |
| 157 | return 1; |
| 158 | default: |
| 159 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 160 | } |
| 161 | case CATCHER_ABORTING: |
| 162 | switch (action) |
| 163 | { |
| 164 | case CATCH_ITER: |
| 165 | { |
| 166 | /* Exit normally if this catcher can handle this |
| 167 | exception. The caller analyses the func return |
| 168 | values. */ |
| 169 | return 0; |
| 170 | } |
| 171 | default: |
| 172 | internal_error (__FILE__, __LINE__, _("bad state")); |
| 173 | } |
| 174 | default: |
| 175 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | int |
| 180 | exceptions_state_mc_catch (struct gdb_exception *exception, |
| 181 | int mask) |
| 182 | { |
| 183 | *exception = current_catcher->exception; |
| 184 | catcher_pop (); |
| 185 | |
| 186 | if (exception->reason < 0) |
| 187 | { |
| 188 | if (mask & RETURN_MASK (exception->reason)) |
| 189 | { |
| 190 | /* Exit normally and let the caller handle the |
| 191 | exception. */ |
| 192 | return 1; |
| 193 | } |
| 194 | |
| 195 | /* The caller didn't request that the event be caught, relay the |
| 196 | event to the next exception_catch/CATCH. */ |
| 197 | throw_exception (*exception); |
| 198 | } |
| 199 | |
| 200 | /* No exception was thrown. */ |
| 201 | return 0; |
| 202 | } |
| 203 | |
| 204 | int |
| 205 | exceptions_state_mc_action_iter (void) |
| 206 | { |
| 207 | return exceptions_state_mc (CATCH_ITER); |
| 208 | } |
| 209 | |
| 210 | int |
| 211 | exceptions_state_mc_action_iter_1 (void) |
| 212 | { |
| 213 | return exceptions_state_mc (CATCH_ITER_1); |
| 214 | } |
| 215 | |
| 216 | #else /* !__cplusplus */ |
| 217 | |
| 218 | /* How many nested TRY blocks we have. See exception_messages and |
| 219 | throw_it. */ |
| 220 | |
| 221 | static int try_scope_depth; |
| 222 | |
| 223 | /* Called on entry to a TRY scope. */ |
| 224 | |
| 225 | void * |
| 226 | exception_try_scope_entry (void) |
| 227 | { |
| 228 | ++try_scope_depth; |
| 229 | return (void *) save_cleanups (); |
| 230 | } |
| 231 | |
| 232 | /* Called on exit of a TRY scope, either normal exit or exception |
| 233 | exit. */ |
| 234 | |
| 235 | void |
| 236 | exception_try_scope_exit (void *saved_state) |
| 237 | { |
| 238 | restore_cleanups ((struct cleanup *) saved_state); |
| 239 | --try_scope_depth; |
| 240 | } |
| 241 | |
| 242 | /* Called by the default catch block. IOW, we'll get here before |
| 243 | jumping out to the next outermost scope an exception if a GDB |
| 244 | exception is not caught. */ |
| 245 | |
| 246 | void |
| 247 | exception_rethrow (void) |
| 248 | { |
| 249 | /* Run this scope's cleanups before re-throwing to the next |
| 250 | outermost scope. */ |
| 251 | prepare_to_throw_exception (); |
| 252 | do_cleanups (all_cleanups ()); |
| 253 | throw; |
| 254 | } |
| 255 | |
| 256 | /* Copy the 'gdb_exception' portion of FROM to TO. */ |
| 257 | |
| 258 | static void |
| 259 | gdb_exception_sliced_copy (struct gdb_exception *to, const struct gdb_exception *from) |
| 260 | { |
| 261 | *to = *from; |
| 262 | } |
| 263 | |
| 264 | #endif /* !__cplusplus */ |
| 265 | |
| 266 | /* Return EXCEPTION to the nearest containing catch_errors(). */ |
| 267 | |
| 268 | void |
| 269 | throw_exception (struct gdb_exception exception) |
| 270 | { |
| 271 | prepare_to_throw_exception (); |
| 272 | |
| 273 | do_cleanups (all_cleanups ()); |
| 274 | |
| 275 | #ifndef __cplusplus |
| 276 | /* Jump to the containing catch_errors() call, communicating REASON |
| 277 | to that call via setjmp's return value. Note that REASON can't |
| 278 | be zero, by definition in defs.h. */ |
| 279 | exceptions_state_mc (CATCH_THROWING); |
| 280 | current_catcher->exception = exception; |
| 281 | SIGLONGJMP (current_catcher->buf, exception.reason); |
| 282 | #else |
| 283 | if (exception.reason == RETURN_QUIT) |
| 284 | { |
| 285 | gdb_exception_RETURN_MASK_QUIT ex; |
| 286 | |
| 287 | gdb_exception_sliced_copy (&ex, &exception); |
| 288 | throw ex; |
| 289 | } |
| 290 | else if (exception.reason == RETURN_ERROR) |
| 291 | { |
| 292 | gdb_exception_RETURN_MASK_ERROR ex; |
| 293 | |
| 294 | gdb_exception_sliced_copy (&ex, &exception); |
| 295 | throw ex; |
| 296 | } |
| 297 | else |
| 298 | gdb_assert_not_reached ("invalid return reason"); |
| 299 | #endif |
| 300 | } |
| 301 | |
| 302 | /* A stack of exception messages. |
| 303 | This is needed to handle nested calls to throw_it: we don't want to |
| 304 | xfree space for a message before it's used. |
| 305 | This can happen if we throw an exception during a cleanup: |
| 306 | An outer TRY_CATCH may have an exception message it wants to print, |
| 307 | but while doing cleanups further calls to throw_it are made. |
| 308 | |
| 309 | This is indexed by the size of the current_catcher list. |
| 310 | It is a dynamically allocated array so that we don't care how deeply |
| 311 | GDB nests its TRY_CATCHs. */ |
| 312 | static char **exception_messages; |
| 313 | |
| 314 | /* The number of currently allocated entries in exception_messages. */ |
| 315 | static int exception_messages_size; |
| 316 | |
| 317 | static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0) |
| 318 | throw_it (enum return_reason reason, enum errors error, const char *fmt, |
| 319 | va_list ap) |
| 320 | { |
| 321 | struct gdb_exception e; |
| 322 | char *new_message; |
| 323 | #ifndef __cplusplus |
| 324 | int depth = catcher_list_size (); |
| 325 | #else |
| 326 | int depth = try_scope_depth; |
| 327 | #endif |
| 328 | |
| 329 | gdb_assert (depth > 0); |
| 330 | |
| 331 | /* Note: The new message may use an old message's text. */ |
| 332 | new_message = xstrvprintf (fmt, ap); |
| 333 | |
| 334 | if (depth > exception_messages_size) |
| 335 | { |
| 336 | int old_size = exception_messages_size; |
| 337 | |
| 338 | exception_messages_size = depth + 10; |
| 339 | exception_messages = (char **) xrealloc (exception_messages, |
| 340 | exception_messages_size |
| 341 | * sizeof (char *)); |
| 342 | memset (exception_messages + old_size, 0, |
| 343 | (exception_messages_size - old_size) * sizeof (char *)); |
| 344 | } |
| 345 | |
| 346 | xfree (exception_messages[depth - 1]); |
| 347 | exception_messages[depth - 1] = new_message; |
| 348 | |
| 349 | /* Create the exception. */ |
| 350 | e.reason = reason; |
| 351 | e.error = error; |
| 352 | e.message = new_message; |
| 353 | |
| 354 | /* Throw the exception. */ |
| 355 | throw_exception (e); |
| 356 | } |
| 357 | |
| 358 | void |
| 359 | throw_verror (enum errors error, const char *fmt, va_list ap) |
| 360 | { |
| 361 | throw_it (RETURN_ERROR, error, fmt, ap); |
| 362 | } |
| 363 | |
| 364 | void |
| 365 | throw_vquit (const char *fmt, va_list ap) |
| 366 | { |
| 367 | throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap); |
| 368 | } |
| 369 | |
| 370 | void |
| 371 | throw_error (enum errors error, const char *fmt, ...) |
| 372 | { |
| 373 | va_list args; |
| 374 | |
| 375 | va_start (args, fmt); |
| 376 | throw_verror (error, fmt, args); |
| 377 | va_end (args); |
| 378 | } |
| 379 | |
| 380 | void |
| 381 | throw_quit (const char *fmt, ...) |
| 382 | { |
| 383 | va_list args; |
| 384 | |
| 385 | va_start (args, fmt); |
| 386 | throw_vquit (fmt, args); |
| 387 | va_end (args); |
| 388 | } |