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1 | /* Exception (throw catch) mechanism, for GDB, the GNU debugger. |
2 | ||
32d0add0 | 3 | Copyright (C) 1986-2015 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 | |
ad6aff7d PA |
23 | const struct gdb_exception exception_none = { 0, GDB_NO_ERROR, NULL }; |
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. */ | |
47 | SIGJMP_BUF buf; | |
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 | ||
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 * | |
492d29ea | 75 | exceptions_state_mc_init (void) |
ff55e1b5 GB |
76 | { |
77 | struct catcher *new_catcher = XCNEW (struct catcher); | |
78 | ||
492d29ea PA |
79 | /* Start with no exception. */ |
80 | new_catcher->exception = exception_none; | |
ff55e1b5 GB |
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: | |
492d29ea | 131 | /* No error/quit has occured. */ |
ff55e1b5 GB |
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. */ | |
ff55e1b5 GB |
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 | { | |
492d29ea PA |
164 | /* Exit normally if this catcher can handle this |
165 | exception. The caller analyses the func return | |
166 | values. */ | |
167 | return 0; | |
ff55e1b5 GB |
168 | } |
169 | default: | |
170 | internal_error (__FILE__, __LINE__, _("bad state")); | |
171 | } | |
172 | default: | |
173 | internal_error (__FILE__, __LINE__, _("bad switch")); | |
174 | } | |
175 | } | |
176 | ||
492d29ea PA |
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 | ||
ff55e1b5 GB |
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); | |
492d29ea | 227 | current_catcher->exception = exception; |
ff55e1b5 GB |
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 | } |