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