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1 | /* Exception (throw catch) mechanism, for GDB, the GNU debugger. |
2 | ||
e2882c85 | 3 | Copyright (C) 1986-2018 Free Software Foundation, Inc. |
ff55e1b5 GB |
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" | |
ff55e1b5 | 22 | |
44a8b4df | 23 | const struct gdb_exception exception_none = { (enum return_reason) 0, GDB_NO_ERROR, NULL }; |
ad6aff7d | 24 | |
ff55e1b5 GB |
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. */ | |
173981bc | 47 | jmp_buf buf; |
ff55e1b5 | 48 | /* Status buffer belonging to the exception handler. */ |
492d29ea | 49 | struct gdb_exception exception; |
ff55e1b5 GB |
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 | ||
89525768 PA |
58 | #if GDB_XCPT == GDB_XCPT_SJMP |
59 | ||
ff55e1b5 GB |
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 | ||
89525768 PA |
76 | #endif |
77 | ||
173981bc | 78 | jmp_buf * |
492d29ea | 79 | exceptions_state_mc_init (void) |
ff55e1b5 GB |
80 | { |
81 | struct catcher *new_catcher = XCNEW (struct catcher); | |
82 | ||
492d29ea PA |
83 | /* Start with no exception. */ |
84 | new_catcher->exception = exception_none; | |
ff55e1b5 GB |
85 | |
86 | /* Prevent error/quit during FUNC from calling cleanups established | |
87 | prior to here. */ | |
88 | new_catcher->saved_cleanup_chain = save_cleanups (); | |
89 | ||
90 | /* Push this new catcher on the top. */ | |
91 | new_catcher->prev = current_catcher; | |
92 | current_catcher = new_catcher; | |
93 | new_catcher->state = CATCHER_CREATED; | |
94 | ||
95 | return &new_catcher->buf; | |
96 | } | |
97 | ||
98 | static void | |
99 | catcher_pop (void) | |
100 | { | |
101 | struct catcher *old_catcher = current_catcher; | |
102 | ||
103 | current_catcher = old_catcher->prev; | |
104 | ||
105 | /* Restore the cleanup chain, the error/quit messages, and the uiout | |
106 | builder, to their original states. */ | |
107 | ||
108 | restore_cleanups (old_catcher->saved_cleanup_chain); | |
109 | ||
110 | xfree (old_catcher); | |
111 | } | |
112 | ||
113 | /* Catcher state machine. Returns non-zero if the m/c should be run | |
114 | again, zero if it should abort. */ | |
115 | ||
116 | static int | |
117 | exceptions_state_mc (enum catcher_action action) | |
118 | { | |
119 | switch (current_catcher->state) | |
120 | { | |
121 | case CATCHER_CREATED: | |
122 | switch (action) | |
123 | { | |
124 | case CATCH_ITER: | |
125 | /* Allow the code to run the catcher. */ | |
126 | current_catcher->state = CATCHER_RUNNING; | |
127 | return 1; | |
128 | default: | |
129 | internal_error (__FILE__, __LINE__, _("bad state")); | |
130 | } | |
131 | case CATCHER_RUNNING: | |
132 | switch (action) | |
133 | { | |
134 | case CATCH_ITER: | |
492d29ea | 135 | /* No error/quit has occured. */ |
ff55e1b5 GB |
136 | return 0; |
137 | case CATCH_ITER_1: | |
138 | current_catcher->state = CATCHER_RUNNING_1; | |
139 | return 1; | |
140 | case CATCH_THROWING: | |
141 | current_catcher->state = CATCHER_ABORTING; | |
142 | /* See also throw_exception. */ | |
143 | return 1; | |
144 | default: | |
145 | internal_error (__FILE__, __LINE__, _("bad switch")); | |
146 | } | |
147 | case CATCHER_RUNNING_1: | |
148 | switch (action) | |
149 | { | |
150 | case CATCH_ITER: | |
151 | /* The did a "break" from the inner while loop. */ | |
ff55e1b5 GB |
152 | return 0; |
153 | case CATCH_ITER_1: | |
154 | current_catcher->state = CATCHER_RUNNING; | |
155 | return 0; | |
156 | case CATCH_THROWING: | |
157 | current_catcher->state = CATCHER_ABORTING; | |
158 | /* See also throw_exception. */ | |
159 | return 1; | |
160 | default: | |
161 | internal_error (__FILE__, __LINE__, _("bad switch")); | |
162 | } | |
163 | case CATCHER_ABORTING: | |
164 | switch (action) | |
165 | { | |
166 | case CATCH_ITER: | |
167 | { | |
492d29ea PA |
168 | /* Exit normally if this catcher can handle this |
169 | exception. The caller analyses the func return | |
170 | values. */ | |
171 | return 0; | |
ff55e1b5 GB |
172 | } |
173 | default: | |
174 | internal_error (__FILE__, __LINE__, _("bad state")); | |
175 | } | |
176 | default: | |
177 | internal_error (__FILE__, __LINE__, _("bad switch")); | |
178 | } | |
179 | } | |
180 | ||
492d29ea PA |
181 | int |
182 | exceptions_state_mc_catch (struct gdb_exception *exception, | |
183 | int mask) | |
184 | { | |
185 | *exception = current_catcher->exception; | |
186 | catcher_pop (); | |
187 | ||
188 | if (exception->reason < 0) | |
189 | { | |
190 | if (mask & RETURN_MASK (exception->reason)) | |
191 | { | |
72df25b2 | 192 | /* Exit normally and let the caller handle the |
492d29ea PA |
193 | exception. */ |
194 | return 1; | |
195 | } | |
196 | ||
197 | /* The caller didn't request that the event be caught, relay the | |
89525768 PA |
198 | event to the next exception_catch/CATCH_SJLJ. */ |
199 | throw_exception_sjlj (*exception); | |
492d29ea PA |
200 | } |
201 | ||
202 | /* No exception was thrown. */ | |
203 | return 0; | |
204 | } | |
205 | ||
ff55e1b5 GB |
206 | int |
207 | exceptions_state_mc_action_iter (void) | |
208 | { | |
209 | return exceptions_state_mc (CATCH_ITER); | |
210 | } | |
211 | ||
212 | int | |
213 | exceptions_state_mc_action_iter_1 (void) | |
214 | { | |
215 | return exceptions_state_mc (CATCH_ITER_1); | |
216 | } | |
217 | ||
89525768 | 218 | #if GDB_XCPT != GDB_XCPT_SJMP |
72df25b2 PA |
219 | |
220 | /* How many nested TRY blocks we have. See exception_messages and | |
221 | throw_it. */ | |
222 | ||
223 | static int try_scope_depth; | |
224 | ||
225 | /* Called on entry to a TRY scope. */ | |
226 | ||
227 | void * | |
228 | exception_try_scope_entry (void) | |
229 | { | |
230 | ++try_scope_depth; | |
231 | return (void *) save_cleanups (); | |
232 | } | |
233 | ||
234 | /* Called on exit of a TRY scope, either normal exit or exception | |
235 | exit. */ | |
236 | ||
237 | void | |
238 | exception_try_scope_exit (void *saved_state) | |
239 | { | |
240 | restore_cleanups ((struct cleanup *) saved_state); | |
241 | --try_scope_depth; | |
242 | } | |
243 | ||
244 | /* Called by the default catch block. IOW, we'll get here before | |
245 | jumping out to the next outermost scope an exception if a GDB | |
246 | exception is not caught. */ | |
247 | ||
248 | void | |
249 | exception_rethrow (void) | |
250 | { | |
251 | /* Run this scope's cleanups before re-throwing to the next | |
252 | outermost scope. */ | |
72df25b2 PA |
253 | do_cleanups (all_cleanups ()); |
254 | throw; | |
255 | } | |
256 | ||
257 | /* Copy the 'gdb_exception' portion of FROM to TO. */ | |
258 | ||
259 | static void | |
260 | gdb_exception_sliced_copy (struct gdb_exception *to, const struct gdb_exception *from) | |
261 | { | |
262 | *to = *from; | |
263 | } | |
264 | ||
eec461d0 | 265 | #endif /* !GDB_XCPT_SJMP */ |
72df25b2 | 266 | |
bf469271 | 267 | /* Return EXCEPTION to the nearest containing CATCH_SJLJ block. */ |
ff55e1b5 GB |
268 | |
269 | void | |
89525768 | 270 | throw_exception_sjlj (struct gdb_exception exception) |
ff55e1b5 | 271 | { |
ff55e1b5 GB |
272 | do_cleanups (all_cleanups ()); |
273 | ||
bf469271 PA |
274 | /* Jump to the nearest CATCH_SJLJ block, communicating REASON to |
275 | that call via setjmp's return value. Note that REASON can't be | |
276 | zero, by definition in common-exceptions.h. */ | |
ff55e1b5 | 277 | exceptions_state_mc (CATCH_THROWING); |
492d29ea | 278 | current_catcher->exception = exception; |
173981bc | 279 | longjmp (current_catcher->buf, exception.reason); |
89525768 PA |
280 | } |
281 | ||
282 | #if GDB_XCPT != GDB_XCPT_SJMP | |
283 | ||
284 | /* Implementation of throw_exception that uses C++ try/catch. */ | |
285 | ||
286 | static ATTRIBUTE_NORETURN void | |
287 | throw_exception_cxx (struct gdb_exception exception) | |
288 | { | |
289 | do_cleanups (all_cleanups ()); | |
290 | ||
72df25b2 PA |
291 | if (exception.reason == RETURN_QUIT) |
292 | { | |
293 | gdb_exception_RETURN_MASK_QUIT ex; | |
294 | ||
295 | gdb_exception_sliced_copy (&ex, &exception); | |
296 | throw ex; | |
297 | } | |
298 | else if (exception.reason == RETURN_ERROR) | |
299 | { | |
300 | gdb_exception_RETURN_MASK_ERROR ex; | |
301 | ||
302 | gdb_exception_sliced_copy (&ex, &exception); | |
303 | throw ex; | |
304 | } | |
305 | else | |
306 | gdb_assert_not_reached ("invalid return reason"); | |
89525768 PA |
307 | } |
308 | ||
309 | #endif | |
310 | ||
311 | void | |
312 | throw_exception (struct gdb_exception exception) | |
313 | { | |
314 | #if GDB_XCPT == GDB_XCPT_SJMP | |
315 | throw_exception_sjlj (exception); | |
316 | #else | |
317 | throw_exception_cxx (exception); | |
72df25b2 | 318 | #endif |
ff55e1b5 GB |
319 | } |
320 | ||
321 | /* A stack of exception messages. | |
322 | This is needed to handle nested calls to throw_it: we don't want to | |
323 | xfree space for a message before it's used. | |
324 | This can happen if we throw an exception during a cleanup: | |
325 | An outer TRY_CATCH may have an exception message it wants to print, | |
326 | but while doing cleanups further calls to throw_it are made. | |
327 | ||
328 | This is indexed by the size of the current_catcher list. | |
329 | It is a dynamically allocated array so that we don't care how deeply | |
330 | GDB nests its TRY_CATCHs. */ | |
331 | static char **exception_messages; | |
332 | ||
333 | /* The number of currently allocated entries in exception_messages. */ | |
334 | static int exception_messages_size; | |
335 | ||
336 | static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0) | |
337 | throw_it (enum return_reason reason, enum errors error, const char *fmt, | |
338 | va_list ap) | |
339 | { | |
340 | struct gdb_exception e; | |
341 | char *new_message; | |
eec461d0 | 342 | #if GDB_XCPT == GDB_XCPT_SJMP |
ff55e1b5 | 343 | int depth = catcher_list_size (); |
72df25b2 PA |
344 | #else |
345 | int depth = try_scope_depth; | |
346 | #endif | |
ff55e1b5 GB |
347 | |
348 | gdb_assert (depth > 0); | |
349 | ||
350 | /* Note: The new message may use an old message's text. */ | |
351 | new_message = xstrvprintf (fmt, ap); | |
352 | ||
353 | if (depth > exception_messages_size) | |
354 | { | |
355 | int old_size = exception_messages_size; | |
356 | ||
357 | exception_messages_size = depth + 10; | |
8d749320 SM |
358 | exception_messages = XRESIZEVEC (char *, exception_messages, |
359 | exception_messages_size); | |
ff55e1b5 GB |
360 | memset (exception_messages + old_size, 0, |
361 | (exception_messages_size - old_size) * sizeof (char *)); | |
362 | } | |
363 | ||
364 | xfree (exception_messages[depth - 1]); | |
365 | exception_messages[depth - 1] = new_message; | |
366 | ||
367 | /* Create the exception. */ | |
368 | e.reason = reason; | |
369 | e.error = error; | |
370 | e.message = new_message; | |
371 | ||
372 | /* Throw the exception. */ | |
373 | throw_exception (e); | |
374 | } | |
375 | ||
376 | void | |
377 | throw_verror (enum errors error, const char *fmt, va_list ap) | |
378 | { | |
379 | throw_it (RETURN_ERROR, error, fmt, ap); | |
380 | } | |
381 | ||
382 | void | |
383 | throw_vquit (const char *fmt, va_list ap) | |
384 | { | |
385 | throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap); | |
386 | } | |
387 | ||
388 | void | |
389 | throw_error (enum errors error, const char *fmt, ...) | |
390 | { | |
391 | va_list args; | |
392 | ||
393 | va_start (args, fmt); | |
394 | throw_verror (error, fmt, args); | |
395 | va_end (args); | |
396 | } | |
397 | ||
398 | void | |
399 | throw_quit (const char *fmt, ...) | |
400 | { | |
401 | va_list args; | |
402 | ||
403 | va_start (args, fmt); | |
404 | throw_vquit (fmt, args); | |
405 | va_end (args); | |
406 | } |