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1 | /* Async events for the GDB event loop. |
2 | Copyright (C) 1999-2019 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include "defs.h" | |
20 | #include "async-event.h" | |
21 | ||
22 | #include "ser-event.h" | |
23 | #include "top.h" | |
24 | ||
25 | /* PROC is a function to be invoked when the READY flag is set. This | |
26 | happens when there has been a signal and the corresponding signal | |
27 | handler has 'triggered' this async_signal_handler for execution. | |
28 | The actual work to be done in response to a signal will be carried | |
29 | out by PROC at a later time, within process_event. This provides a | |
30 | deferred execution of signal handlers. | |
31 | ||
32 | Async_init_signals takes care of setting up such an | |
33 | async_signal_handler for each interesting signal. */ | |
34 | ||
35 | typedef struct async_signal_handler | |
36 | { | |
37 | int ready; /* If ready, call this handler | |
38 | from the main event loop, using | |
39 | invoke_async_handler. */ | |
40 | struct async_signal_handler *next_handler; /* Ptr to next handler. */ | |
41 | sig_handler_func *proc; /* Function to call to do the work. */ | |
42 | gdb_client_data client_data; /* Argument to async_handler_func. */ | |
43 | } | |
44 | async_signal_handler; | |
45 | ||
46 | /* PROC is a function to be invoked when the READY flag is set. This | |
47 | happens when the event has been marked with | |
48 | MARK_ASYNC_EVENT_HANDLER. The actual work to be done in response | |
49 | to an event will be carried out by PROC at a later time, within | |
50 | process_event. This provides a deferred execution of event | |
51 | handlers. */ | |
52 | typedef struct async_event_handler | |
53 | { | |
54 | /* If ready, call this handler from the main event loop, using | |
55 | invoke_event_handler. */ | |
56 | int ready; | |
57 | ||
58 | /* Point to next handler. */ | |
59 | struct async_event_handler *next_handler; | |
60 | ||
61 | /* Function to call to do the work. */ | |
62 | async_event_handler_func *proc; | |
63 | ||
64 | /* Argument to PROC. */ | |
65 | gdb_client_data client_data; | |
66 | } | |
67 | async_event_handler; | |
68 | ||
69 | /* All the async_signal_handlers gdb is interested in are kept onto | |
70 | this list. */ | |
71 | static struct | |
72 | { | |
73 | /* Pointer to first in handler list. */ | |
74 | async_signal_handler *first_handler; | |
75 | ||
76 | /* Pointer to last in handler list. */ | |
77 | async_signal_handler *last_handler; | |
78 | } | |
79 | sighandler_list; | |
80 | ||
81 | /* All the async_event_handlers gdb is interested in are kept onto | |
82 | this list. */ | |
83 | static struct | |
84 | { | |
85 | /* Pointer to first in handler list. */ | |
86 | async_event_handler *first_handler; | |
87 | ||
88 | /* Pointer to last in handler list. */ | |
89 | async_event_handler *last_handler; | |
90 | } | |
91 | async_event_handler_list; | |
92 | ||
93 | ||
94 | /* This event is signalled whenever an asynchronous handler needs to | |
95 | defer an action to the event loop. */ | |
96 | static struct serial_event *async_signal_handlers_serial_event; | |
97 | ||
98 | /* Callback registered with ASYNC_SIGNAL_HANDLERS_SERIAL_EVENT. */ | |
99 | ||
100 | static void | |
101 | async_signals_handler (int error, gdb_client_data client_data) | |
102 | { | |
103 | /* Do nothing. Handlers are run by invoke_async_signal_handlers | |
104 | from instead. */ | |
105 | } | |
106 | ||
107 | void | |
108 | initialize_async_signal_handlers (void) | |
109 | { | |
110 | async_signal_handlers_serial_event = make_serial_event (); | |
111 | ||
112 | add_file_handler (serial_event_fd (async_signal_handlers_serial_event), | |
113 | async_signals_handler, NULL); | |
114 | } | |
115 | ||
116 | \f | |
117 | ||
118 | /* Create an asynchronous handler, allocating memory for it. | |
119 | Return a pointer to the newly created handler. | |
120 | This pointer will be used to invoke the handler by | |
121 | invoke_async_signal_handler. | |
122 | PROC is the function to call with CLIENT_DATA argument | |
123 | whenever the handler is invoked. */ | |
124 | async_signal_handler * | |
125 | create_async_signal_handler (sig_handler_func * proc, | |
126 | gdb_client_data client_data) | |
127 | { | |
128 | async_signal_handler *async_handler_ptr; | |
129 | ||
130 | async_handler_ptr = XNEW (async_signal_handler); | |
131 | async_handler_ptr->ready = 0; | |
132 | async_handler_ptr->next_handler = NULL; | |
133 | async_handler_ptr->proc = proc; | |
134 | async_handler_ptr->client_data = client_data; | |
135 | if (sighandler_list.first_handler == NULL) | |
136 | sighandler_list.first_handler = async_handler_ptr; | |
137 | else | |
138 | sighandler_list.last_handler->next_handler = async_handler_ptr; | |
139 | sighandler_list.last_handler = async_handler_ptr; | |
140 | return async_handler_ptr; | |
141 | } | |
142 | ||
143 | /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information | |
144 | will be used when the handlers are invoked, after we have waited | |
145 | for some event. The caller of this function is the interrupt | |
146 | handler associated with a signal. */ | |
147 | void | |
148 | mark_async_signal_handler (async_signal_handler * async_handler_ptr) | |
149 | { | |
150 | async_handler_ptr->ready = 1; | |
151 | serial_event_set (async_signal_handlers_serial_event); | |
152 | } | |
153 | ||
154 | /* See event-loop.h. */ | |
155 | ||
156 | void | |
157 | clear_async_signal_handler (async_signal_handler *async_handler_ptr) | |
158 | { | |
159 | async_handler_ptr->ready = 0; | |
160 | } | |
161 | ||
162 | /* See event-loop.h. */ | |
163 | ||
164 | int | |
165 | async_signal_handler_is_marked (async_signal_handler *async_handler_ptr) | |
166 | { | |
167 | return async_handler_ptr->ready; | |
168 | } | |
169 | ||
170 | /* Call all the handlers that are ready. Returns true if any was | |
171 | indeed ready. */ | |
172 | ||
173 | int | |
174 | invoke_async_signal_handlers (void) | |
175 | { | |
176 | async_signal_handler *async_handler_ptr; | |
177 | int any_ready = 0; | |
178 | ||
179 | /* We're going to handle all pending signals, so no need to wake up | |
180 | the event loop again the next time around. Note this must be | |
181 | cleared _before_ calling the callbacks, to avoid races. */ | |
182 | serial_event_clear (async_signal_handlers_serial_event); | |
183 | ||
184 | /* Invoke all ready handlers. */ | |
185 | ||
186 | while (1) | |
187 | { | |
188 | for (async_handler_ptr = sighandler_list.first_handler; | |
189 | async_handler_ptr != NULL; | |
190 | async_handler_ptr = async_handler_ptr->next_handler) | |
191 | { | |
192 | if (async_handler_ptr->ready) | |
193 | break; | |
194 | } | |
195 | if (async_handler_ptr == NULL) | |
196 | break; | |
197 | any_ready = 1; | |
198 | async_handler_ptr->ready = 0; | |
199 | /* Async signal handlers have no connection to whichever was the | |
200 | current UI, and thus always run on the main one. */ | |
201 | current_ui = main_ui; | |
202 | (*async_handler_ptr->proc) (async_handler_ptr->client_data); | |
203 | } | |
204 | ||
205 | return any_ready; | |
206 | } | |
207 | ||
208 | /* Delete an asynchronous handler (ASYNC_HANDLER_PTR). | |
209 | Free the space allocated for it. */ | |
210 | void | |
211 | delete_async_signal_handler (async_signal_handler ** async_handler_ptr) | |
212 | { | |
213 | async_signal_handler *prev_ptr; | |
214 | ||
215 | if (sighandler_list.first_handler == (*async_handler_ptr)) | |
216 | { | |
217 | sighandler_list.first_handler = (*async_handler_ptr)->next_handler; | |
218 | if (sighandler_list.first_handler == NULL) | |
219 | sighandler_list.last_handler = NULL; | |
220 | } | |
221 | else | |
222 | { | |
223 | prev_ptr = sighandler_list.first_handler; | |
224 | while (prev_ptr && prev_ptr->next_handler != (*async_handler_ptr)) | |
225 | prev_ptr = prev_ptr->next_handler; | |
226 | gdb_assert (prev_ptr); | |
227 | prev_ptr->next_handler = (*async_handler_ptr)->next_handler; | |
228 | if (sighandler_list.last_handler == (*async_handler_ptr)) | |
229 | sighandler_list.last_handler = prev_ptr; | |
230 | } | |
231 | xfree ((*async_handler_ptr)); | |
232 | (*async_handler_ptr) = NULL; | |
233 | } | |
234 | ||
235 | /* Create an asynchronous event handler, allocating memory for it. | |
236 | Return a pointer to the newly created handler. PROC is the | |
237 | function to call with CLIENT_DATA argument whenever the handler is | |
238 | invoked. */ | |
239 | async_event_handler * | |
240 | create_async_event_handler (async_event_handler_func *proc, | |
241 | gdb_client_data client_data) | |
242 | { | |
243 | async_event_handler *h; | |
244 | ||
245 | h = XNEW (struct async_event_handler); | |
246 | h->ready = 0; | |
247 | h->next_handler = NULL; | |
248 | h->proc = proc; | |
249 | h->client_data = client_data; | |
250 | if (async_event_handler_list.first_handler == NULL) | |
251 | async_event_handler_list.first_handler = h; | |
252 | else | |
253 | async_event_handler_list.last_handler->next_handler = h; | |
254 | async_event_handler_list.last_handler = h; | |
255 | return h; | |
256 | } | |
257 | ||
258 | /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information | |
259 | will be used by gdb_do_one_event. The caller will be whoever | |
260 | created the event source, and wants to signal that the event is | |
261 | ready to be handled. */ | |
262 | void | |
263 | mark_async_event_handler (async_event_handler *async_handler_ptr) | |
264 | { | |
265 | async_handler_ptr->ready = 1; | |
266 | } | |
267 | ||
268 | /* See event-loop.h. */ | |
269 | ||
270 | void | |
271 | clear_async_event_handler (async_event_handler *async_handler_ptr) | |
272 | { | |
273 | async_handler_ptr->ready = 0; | |
274 | } | |
275 | ||
276 | /* Check if asynchronous event handlers are ready, and call the | |
277 | handler function for one that is. */ | |
278 | ||
279 | int | |
280 | check_async_event_handlers () | |
281 | { | |
282 | async_event_handler *async_handler_ptr; | |
283 | ||
284 | for (async_handler_ptr = async_event_handler_list.first_handler; | |
285 | async_handler_ptr != NULL; | |
286 | async_handler_ptr = async_handler_ptr->next_handler) | |
287 | { | |
288 | if (async_handler_ptr->ready) | |
289 | { | |
290 | async_handler_ptr->ready = 0; | |
291 | (*async_handler_ptr->proc) (async_handler_ptr->client_data); | |
292 | return 1; | |
293 | } | |
294 | } | |
295 | ||
296 | return 0; | |
297 | } | |
298 | ||
299 | /* Delete an asynchronous handler (ASYNC_HANDLER_PTR). | |
300 | Free the space allocated for it. */ | |
301 | void | |
302 | delete_async_event_handler (async_event_handler **async_handler_ptr) | |
303 | { | |
304 | async_event_handler *prev_ptr; | |
305 | ||
306 | if (async_event_handler_list.first_handler == *async_handler_ptr) | |
307 | { | |
308 | async_event_handler_list.first_handler | |
309 | = (*async_handler_ptr)->next_handler; | |
310 | if (async_event_handler_list.first_handler == NULL) | |
311 | async_event_handler_list.last_handler = NULL; | |
312 | } | |
313 | else | |
314 | { | |
315 | prev_ptr = async_event_handler_list.first_handler; | |
316 | while (prev_ptr && prev_ptr->next_handler != *async_handler_ptr) | |
317 | prev_ptr = prev_ptr->next_handler; | |
318 | gdb_assert (prev_ptr); | |
319 | prev_ptr->next_handler = (*async_handler_ptr)->next_handler; | |
320 | if (async_event_handler_list.last_handler == (*async_handler_ptr)) | |
321 | async_event_handler_list.last_handler = prev_ptr; | |
322 | } | |
323 | xfree (*async_handler_ptr); | |
324 | *async_handler_ptr = NULL; | |
325 | } |