| 1 | /* Async events for the GDB event loop. |
| 2 | Copyright (C) 1999-2021 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 | struct async_signal_handler |
| 36 | { |
| 37 | /* If ready, call this handler from the main event loop, using |
| 38 | invoke_async_handler. */ |
| 39 | int ready; |
| 40 | |
| 41 | /* Pointer to next handler. */ |
| 42 | struct async_signal_handler *next_handler; |
| 43 | |
| 44 | /* Function to call to do the work. */ |
| 45 | sig_handler_func *proc; |
| 46 | |
| 47 | /* Argument to PROC. */ |
| 48 | gdb_client_data client_data; |
| 49 | |
| 50 | /* User-friendly name of this handler. */ |
| 51 | const char *name; |
| 52 | }; |
| 53 | |
| 54 | /* PROC is a function to be invoked when the READY flag is set. This |
| 55 | happens when the event has been marked with |
| 56 | MARK_ASYNC_EVENT_HANDLER. The actual work to be done in response |
| 57 | to an event will be carried out by PROC at a later time, within |
| 58 | process_event. This provides a deferred execution of event |
| 59 | handlers. */ |
| 60 | struct async_event_handler |
| 61 | { |
| 62 | /* If ready, call this handler from the main event loop, using |
| 63 | invoke_event_handler. */ |
| 64 | int ready; |
| 65 | |
| 66 | /* Pointer to next handler. */ |
| 67 | struct async_event_handler *next_handler; |
| 68 | |
| 69 | /* Function to call to do the work. */ |
| 70 | async_event_handler_func *proc; |
| 71 | |
| 72 | /* Argument to PROC. */ |
| 73 | gdb_client_data client_data; |
| 74 | |
| 75 | /* User-friendly name of this handler. */ |
| 76 | const char *name; |
| 77 | }; |
| 78 | |
| 79 | /* All the async_signal_handlers gdb is interested in are kept onto |
| 80 | this list. */ |
| 81 | static struct |
| 82 | { |
| 83 | /* Pointer to first in handler list. */ |
| 84 | async_signal_handler *first_handler; |
| 85 | |
| 86 | /* Pointer to last in handler list. */ |
| 87 | async_signal_handler *last_handler; |
| 88 | } |
| 89 | sighandler_list; |
| 90 | |
| 91 | /* All the async_event_handlers gdb is interested in are kept onto |
| 92 | this list. */ |
| 93 | static struct |
| 94 | { |
| 95 | /* Pointer to first in handler list. */ |
| 96 | async_event_handler *first_handler; |
| 97 | |
| 98 | /* Pointer to last in handler list. */ |
| 99 | async_event_handler *last_handler; |
| 100 | } |
| 101 | async_event_handler_list; |
| 102 | |
| 103 | |
| 104 | /* This event is signalled whenever an asynchronous handler needs to |
| 105 | defer an action to the event loop. */ |
| 106 | static struct serial_event *async_signal_handlers_serial_event; |
| 107 | |
| 108 | /* Callback registered with ASYNC_SIGNAL_HANDLERS_SERIAL_EVENT. */ |
| 109 | |
| 110 | static void |
| 111 | async_signals_handler (int error, gdb_client_data client_data) |
| 112 | { |
| 113 | /* Do nothing. Handlers are run by invoke_async_signal_handlers |
| 114 | from instead. */ |
| 115 | } |
| 116 | |
| 117 | void |
| 118 | initialize_async_signal_handlers (void) |
| 119 | { |
| 120 | async_signal_handlers_serial_event = make_serial_event (); |
| 121 | |
| 122 | add_file_handler (serial_event_fd (async_signal_handlers_serial_event), |
| 123 | async_signals_handler, NULL, "async-signals"); |
| 124 | } |
| 125 | |
| 126 | \f |
| 127 | |
| 128 | /* Create an asynchronous handler, allocating memory for it. |
| 129 | Return a pointer to the newly created handler. |
| 130 | This pointer will be used to invoke the handler by |
| 131 | invoke_async_signal_handler. |
| 132 | PROC is the function to call with CLIENT_DATA argument |
| 133 | whenever the handler is invoked. */ |
| 134 | async_signal_handler * |
| 135 | create_async_signal_handler (sig_handler_func * proc, |
| 136 | gdb_client_data client_data, |
| 137 | const char *name) |
| 138 | { |
| 139 | async_signal_handler *async_handler_ptr; |
| 140 | |
| 141 | async_handler_ptr = XNEW (async_signal_handler); |
| 142 | async_handler_ptr->ready = 0; |
| 143 | async_handler_ptr->next_handler = NULL; |
| 144 | async_handler_ptr->proc = proc; |
| 145 | async_handler_ptr->client_data = client_data; |
| 146 | async_handler_ptr->name = name; |
| 147 | if (sighandler_list.first_handler == NULL) |
| 148 | sighandler_list.first_handler = async_handler_ptr; |
| 149 | else |
| 150 | sighandler_list.last_handler->next_handler = async_handler_ptr; |
| 151 | sighandler_list.last_handler = async_handler_ptr; |
| 152 | return async_handler_ptr; |
| 153 | } |
| 154 | |
| 155 | /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information |
| 156 | will be used when the handlers are invoked, after we have waited |
| 157 | for some event. The caller of this function is the interrupt |
| 158 | handler associated with a signal. */ |
| 159 | void |
| 160 | mark_async_signal_handler (async_signal_handler *async_handler_ptr) |
| 161 | { |
| 162 | if (debug_event_loop != debug_event_loop_kind::OFF) |
| 163 | { |
| 164 | /* This is called by signal handlers, so we print it "by hand" using |
| 165 | the async-signal-safe methods. */ |
| 166 | const char head[] = ("[event-loop] mark_async_signal_handler: marking" |
| 167 | "async signal handler `"); |
| 168 | gdb_stdlog->write_async_safe (head, strlen (head)); |
| 169 | |
| 170 | gdb_stdlog->write_async_safe (async_handler_ptr->name, |
| 171 | strlen (async_handler_ptr->name)); |
| 172 | |
| 173 | const char tail[] = "`\n"; |
| 174 | gdb_stdlog->write_async_safe (tail, strlen (tail)); |
| 175 | } |
| 176 | |
| 177 | async_handler_ptr->ready = 1; |
| 178 | serial_event_set (async_signal_handlers_serial_event); |
| 179 | } |
| 180 | |
| 181 | /* See event-loop.h. */ |
| 182 | |
| 183 | void |
| 184 | clear_async_signal_handler (async_signal_handler *async_handler_ptr) |
| 185 | { |
| 186 | event_loop_debug_printf ("clearing async signal handler `%s`", |
| 187 | async_handler_ptr->name); |
| 188 | async_handler_ptr->ready = 0; |
| 189 | } |
| 190 | |
| 191 | /* See event-loop.h. */ |
| 192 | |
| 193 | int |
| 194 | async_signal_handler_is_marked (async_signal_handler *async_handler_ptr) |
| 195 | { |
| 196 | return async_handler_ptr->ready; |
| 197 | } |
| 198 | |
| 199 | /* Call all the handlers that are ready. Returns true if any was |
| 200 | indeed ready. */ |
| 201 | |
| 202 | int |
| 203 | invoke_async_signal_handlers (void) |
| 204 | { |
| 205 | async_signal_handler *async_handler_ptr; |
| 206 | int any_ready = 0; |
| 207 | |
| 208 | /* We're going to handle all pending signals, so no need to wake up |
| 209 | the event loop again the next time around. Note this must be |
| 210 | cleared _before_ calling the callbacks, to avoid races. */ |
| 211 | serial_event_clear (async_signal_handlers_serial_event); |
| 212 | |
| 213 | /* Invoke all ready handlers. */ |
| 214 | |
| 215 | while (1) |
| 216 | { |
| 217 | for (async_handler_ptr = sighandler_list.first_handler; |
| 218 | async_handler_ptr != NULL; |
| 219 | async_handler_ptr = async_handler_ptr->next_handler) |
| 220 | { |
| 221 | if (async_handler_ptr->ready) |
| 222 | break; |
| 223 | } |
| 224 | if (async_handler_ptr == NULL) |
| 225 | break; |
| 226 | any_ready = 1; |
| 227 | async_handler_ptr->ready = 0; |
| 228 | /* Async signal handlers have no connection to whichever was the |
| 229 | current UI, and thus always run on the main one. */ |
| 230 | current_ui = main_ui; |
| 231 | event_loop_debug_printf ("invoking async signal handler `%s`", |
| 232 | async_handler_ptr->name); |
| 233 | (*async_handler_ptr->proc) (async_handler_ptr->client_data); |
| 234 | } |
| 235 | |
| 236 | return any_ready; |
| 237 | } |
| 238 | |
| 239 | /* Delete an asynchronous handler (ASYNC_HANDLER_PTR). |
| 240 | Free the space allocated for it. */ |
| 241 | void |
| 242 | delete_async_signal_handler (async_signal_handler ** async_handler_ptr) |
| 243 | { |
| 244 | async_signal_handler *prev_ptr; |
| 245 | |
| 246 | if (sighandler_list.first_handler == (*async_handler_ptr)) |
| 247 | { |
| 248 | sighandler_list.first_handler = (*async_handler_ptr)->next_handler; |
| 249 | if (sighandler_list.first_handler == NULL) |
| 250 | sighandler_list.last_handler = NULL; |
| 251 | } |
| 252 | else |
| 253 | { |
| 254 | prev_ptr = sighandler_list.first_handler; |
| 255 | while (prev_ptr && prev_ptr->next_handler != (*async_handler_ptr)) |
| 256 | prev_ptr = prev_ptr->next_handler; |
| 257 | gdb_assert (prev_ptr); |
| 258 | prev_ptr->next_handler = (*async_handler_ptr)->next_handler; |
| 259 | if (sighandler_list.last_handler == (*async_handler_ptr)) |
| 260 | sighandler_list.last_handler = prev_ptr; |
| 261 | } |
| 262 | xfree ((*async_handler_ptr)); |
| 263 | (*async_handler_ptr) = NULL; |
| 264 | } |
| 265 | |
| 266 | /* See async-event.h. */ |
| 267 | |
| 268 | async_event_handler * |
| 269 | create_async_event_handler (async_event_handler_func *proc, |
| 270 | gdb_client_data client_data, |
| 271 | const char *name) |
| 272 | { |
| 273 | async_event_handler *h; |
| 274 | |
| 275 | h = XNEW (struct async_event_handler); |
| 276 | h->ready = 0; |
| 277 | h->next_handler = NULL; |
| 278 | h->proc = proc; |
| 279 | h->client_data = client_data; |
| 280 | h->name = name; |
| 281 | if (async_event_handler_list.first_handler == NULL) |
| 282 | async_event_handler_list.first_handler = h; |
| 283 | else |
| 284 | async_event_handler_list.last_handler->next_handler = h; |
| 285 | async_event_handler_list.last_handler = h; |
| 286 | return h; |
| 287 | } |
| 288 | |
| 289 | /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information |
| 290 | will be used by gdb_do_one_event. The caller will be whoever |
| 291 | created the event source, and wants to signal that the event is |
| 292 | ready to be handled. */ |
| 293 | void |
| 294 | mark_async_event_handler (async_event_handler *async_handler_ptr) |
| 295 | { |
| 296 | event_loop_debug_printf ("marking async event handler `%s`", |
| 297 | async_handler_ptr->name); |
| 298 | async_handler_ptr->ready = 1; |
| 299 | } |
| 300 | |
| 301 | /* See event-loop.h. */ |
| 302 | |
| 303 | void |
| 304 | clear_async_event_handler (async_event_handler *async_handler_ptr) |
| 305 | { |
| 306 | event_loop_debug_printf ("clearing async event handler `%s`", |
| 307 | async_handler_ptr->name); |
| 308 | async_handler_ptr->ready = 0; |
| 309 | } |
| 310 | |
| 311 | /* Check if asynchronous event handlers are ready, and call the |
| 312 | handler function for one that is. */ |
| 313 | |
| 314 | int |
| 315 | check_async_event_handlers () |
| 316 | { |
| 317 | async_event_handler *async_handler_ptr; |
| 318 | |
| 319 | for (async_handler_ptr = async_event_handler_list.first_handler; |
| 320 | async_handler_ptr != NULL; |
| 321 | async_handler_ptr = async_handler_ptr->next_handler) |
| 322 | { |
| 323 | if (async_handler_ptr->ready) |
| 324 | { |
| 325 | event_loop_debug_printf ("invoking async event handler `%s`", |
| 326 | async_handler_ptr->name); |
| 327 | (*async_handler_ptr->proc) (async_handler_ptr->client_data); |
| 328 | return 1; |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | return 0; |
| 333 | } |
| 334 | |
| 335 | /* Delete an asynchronous handler (ASYNC_HANDLER_PTR). |
| 336 | Free the space allocated for it. */ |
| 337 | void |
| 338 | delete_async_event_handler (async_event_handler **async_handler_ptr) |
| 339 | { |
| 340 | async_event_handler *prev_ptr; |
| 341 | |
| 342 | if (async_event_handler_list.first_handler == *async_handler_ptr) |
| 343 | { |
| 344 | async_event_handler_list.first_handler |
| 345 | = (*async_handler_ptr)->next_handler; |
| 346 | if (async_event_handler_list.first_handler == NULL) |
| 347 | async_event_handler_list.last_handler = NULL; |
| 348 | } |
| 349 | else |
| 350 | { |
| 351 | prev_ptr = async_event_handler_list.first_handler; |
| 352 | while (prev_ptr && prev_ptr->next_handler != *async_handler_ptr) |
| 353 | prev_ptr = prev_ptr->next_handler; |
| 354 | gdb_assert (prev_ptr); |
| 355 | prev_ptr->next_handler = (*async_handler_ptr)->next_handler; |
| 356 | if (async_event_handler_list.last_handler == (*async_handler_ptr)) |
| 357 | async_event_handler_list.last_handler = prev_ptr; |
| 358 | } |
| 359 | xfree (*async_handler_ptr); |
| 360 | *async_handler_ptr = NULL; |
| 361 | } |