uloop.c

   1 /*
   2  * uloop - event loop implementation
   3  *
   4  * Copyright (C) 2010-2016 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18 #include <sys/time.h>
  19 #include <sys/types.h>
  20
  21 #include <unistd.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <errno.h>
  25 #include <poll.h>
  26 #include <string.h>
  27 #include <fcntl.h>
  28 #include <stdbool.h>
  29
  30 #include "uloop.h"
  31 #include "utils.h"
  32
  33 #ifdef USE_KQUEUE
  34 #include <sys/event.h>
  35 #endif
  36 #ifdef USE_EPOLL
  37 #include <sys/epoll.h>
  38 #endif
  39 #include <sys/wait.h>
  40
  41 struct uloop_fd_event {
  42         struct uloop_fd *fd;
  43         unsigned int events;
  44 };
  45
  46 struct uloop_fd_stack {
  47         struct uloop_fd_stack *next;
  48         struct uloop_fd *fd;
  49         unsigned int events;
  50 };
  51
  52 static struct uloop_fd_stack *fd_stack = NULL;
  53
  54 #define ULOOP_MAX_EVENTS 10
  55
  56 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
  57 static struct list_head processes = LIST_HEAD_INIT(processes);
  58
  59 static int signal_fd = -1;
  60 static int poll_fd = -1;
  61 bool uloop_cancelled = false;
  62 static bool do_sigchld = false;
  63
  64 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  65 static int cur_fd, cur_nfds;
  66
  67 static void uloop_handle_signal(int signo);
  68
  69 #ifdef USE_KQUEUE
  70 #include "uloop-kqueue.c"
  71 #endif
  72
  73 #ifdef USE_EPOLL
  74 #include "uloop-epoll.c"
  75 #endif
  76
  77 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
  78 {
  79         struct uloop_fd_stack *cur;
  80
  81         /*
  82          * Do not buffer events for level-triggered fds, they will keep firing.
  83          * Caller needs to take care of recursion issues.
  84          */
  85         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
  86                 return false;
  87
  88         for (cur = fd_stack; cur; cur = cur->next) {
  89                 if (cur->fd != fd)
  90                         continue;
  91
  92                 if (events < 0)
  93                         cur->fd = NULL;
  94                 else
  95                         cur->events |= events | ULOOP_EVENT_BUFFERED;
  96
  97                 return true;
  98         }
  99
 100         return false;
 101 }
 102
 103 static void uloop_run_events(int timeout)
 104 {
 105         struct uloop_fd_event *cur;
 106         struct uloop_fd *fd;
 107
 108         if (!cur_nfds) {
 109                 cur_fd = 0;
 110                 cur_nfds = uloop_fetch_events(timeout);
 111                 if (cur_nfds < 0)
 112                         cur_nfds = 0;
 113         }
 114
 115         while (cur_nfds > 0) {
 116                 struct uloop_fd_stack stack_cur;
 117                 unsigned int events;
 118
 119                 cur = &cur_fds[cur_fd++];
 120                 cur_nfds--;
 121
 122                 fd = cur->fd;
 123                 events = cur->events;
 124                 if (!fd)
 125                         continue;
 126
 127                 if (!fd->cb)
 128                         continue;
 129
 130                 if (uloop_fd_stack_event(fd, cur->events))
 131                         continue;
 132
 133                 stack_cur.next = fd_stack;
 134                 stack_cur.fd = fd;
 135                 fd_stack = &stack_cur;
 136                 do {
 137                         stack_cur.events = 0;
 138                         fd->cb(fd, events);
 139                         events = stack_cur.events & ULOOP_EVENT_MASK;
 140                 } while (stack_cur.fd && events);
 141                 fd_stack = stack_cur.next;
 142
 143                 return;
 144         }
 145 }
 146
 147 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 148 {
 149         unsigned int fl;
 150         int ret;
 151
 152         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 153                 return uloop_fd_delete(sock);
 154
 155         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 156                 fl = fcntl(sock->fd, F_GETFL, 0);
 157                 fl |= O_NONBLOCK;
 158                 fcntl(sock->fd, F_SETFL, fl);
 159         }
 160
 161         ret = register_poll(sock, flags);
 162         if (ret < 0)
 163                 goto out;
 164
 165         sock->registered = true;
 166         sock->eof = false;
 167         sock->error = false;
 168
 169 out:
 170         return ret;
 171 }
 172
 173 int uloop_fd_delete(struct uloop_fd *fd)
 174 {
 175         int i;
 176
 177         for (i = 0; i < cur_nfds; i++) {
 178                 if (cur_fds[cur_fd + i].fd != fd)
 179                         continue;
 180
 181                 cur_fds[cur_fd + i].fd = NULL;
 182         }
 183
 184         if (!fd->registered)
 185                 return 0;
 186
 187         fd->registered = false;
 188         uloop_fd_stack_event(fd, -1);
 189         return __uloop_fd_delete(fd);
 190 }
 191
 192 static int tv_diff(struct timeval *t1, struct timeval *t2)
 193 {
 194         return
 195                 (t1->tv_sec - t2->tv_sec) * 1000 +
 196                 (t1->tv_usec - t2->tv_usec) / 1000;
 197 }
 198
 199 int uloop_timeout_add(struct uloop_timeout *timeout)
 200 {
 201         struct uloop_timeout *tmp;
 202         struct list_head *h = &timeouts;
 203
 204         if (timeout->pending)
 205                 return -1;
 206
 207         list_for_each_entry(tmp, &timeouts, list) {
 208                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 209                         h = &tmp->list;
 210                         break;
 211                 }
 212         }
 213
 214         list_add_tail(&timeout->list, h);
 215         timeout->pending = true;
 216
 217         return 0;
 218 }
 219
 220 static void uloop_gettime(struct timeval *tv)
 221 {
 222         struct timespec ts;
 223
 224         clock_gettime(CLOCK_MONOTONIC, &ts);
 225         tv->tv_sec = ts.tv_sec;
 226         tv->tv_usec = ts.tv_nsec / 1000;
 227 }
 228
 229 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 230 {
 231         struct timeval *time = &timeout->time;
 232
 233         if (timeout->pending)
 234                 uloop_timeout_cancel(timeout);
 235
 236         uloop_gettime(time);
 237
 238         time->tv_sec += msecs / 1000;
 239         time->tv_usec += (msecs % 1000) * 1000;
 240
 241         if (time->tv_usec > 1000000) {
 242                 time->tv_sec++;
 243                 time->tv_usec -= 1000000;
 244         }
 245
 246         return uloop_timeout_add(timeout);
 247 }
 248
 249 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 250 {
 251         if (!timeout->pending)
 252                 return -1;
 253
 254         list_del(&timeout->list);
 255         timeout->pending = false;
 256
 257         return 0;
 258 }
 259
 260 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 261 {
 262         struct timeval now;
 263
 264         if (!timeout->pending)
 265                 return -1;
 266
 267         uloop_gettime(&now);
 268
 269         return tv_diff(&timeout->time, &now);
 270 }
 271
 272 int uloop_process_add(struct uloop_process *p)
 273 {
 274         struct uloop_process *tmp;
 275         struct list_head *h = &processes;
 276
 277         if (p->pending)
 278                 return -1;
 279
 280         list_for_each_entry(tmp, &processes, list) {
 281                 if (tmp->pid > p->pid) {
 282                         h = &tmp->list;
 283                         break;
 284                 }
 285         }
 286
 287         list_add_tail(&p->list, h);
 288         p->pending = true;
 289
 290         return 0;
 291 }
 292
 293 int uloop_process_delete(struct uloop_process *p)
 294 {
 295         if (!p->pending)
 296                 return -1;
 297
 298         list_del(&p->list);
 299         p->pending = false;
 300
 301         return 0;
 302 }
 303
 304 static void uloop_handle_processes(void)
 305 {
 306         struct uloop_process *p, *tmp;
 307         pid_t pid;
 308         int ret;
 309
 310         do_sigchld = false;
 311
 312         while (1) {
 313                 pid = waitpid(-1, &ret, WNOHANG);
 314                 if (pid < 0 && errno == EINTR)
 315                         continue;
 316
 317                 if (pid <= 0)
 318                         return;
 319
 320                 list_for_each_entry_safe(p, tmp, &processes, list) {
 321                         if (p->pid < pid)
 322                                 continue;
 323
 324                         if (p->pid > pid)
 325                                 break;
 326
 327                         uloop_process_delete(p);
 328                         p->cb(p, ret);
 329                 }
 330         }
 331
 332 }
 333
 334 static void uloop_handle_signal(int signo)
 335 {
 336         switch (signo) {
 337         case SIGINT:
 338         case SIGQUIT:
 339         case SIGTERM:
 340                 uloop_cancelled = true;
 341                 break;
 342         case SIGCHLD:
 343                 do_sigchld = true;
 344         }
 345 }
 346
 347 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 348 {
 349         struct sigaction s;
 350         struct sigaction *act;
 351
 352         act = NULL;
 353         sigaction(signum, NULL, &s);
 354
 355         if (add) {
 356                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 357                         memcpy(old, &s, sizeof(struct sigaction));
 358                         s.sa_handler = handler;
 359                         s.sa_flags = 0;
 360                         act = &s;
 361                 }
 362         }
 363         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 364                         act = old;
 365         }
 366
 367         if (act != NULL)
 368                 sigaction(signum, act, NULL);
 369 }
 370
 371 static void uloop_ignore_signal(int signum, bool ignore)
 372 {
 373         struct sigaction s;
 374         void *new_handler = NULL;
 375
 376         sigaction(signum, NULL, &s);
 377
 378         if (ignore) {
 379                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 380                         new_handler = SIG_IGN;
 381         } else {
 382                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 383                         new_handler = SIG_DFL;
 384         }
 385
 386         if (new_handler) {
 387                 s.sa_handler = new_handler;
 388                 s.sa_flags = 0;
 389                 sigaction(signum, &s, NULL);
 390         }
 391 }
 392
 393 static void uloop_setup_signals(bool add)
 394 {
 395         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 396
 397         if (uloop_setup_signalfd(add))
 398                 return;
 399
 400         uloop_install_handler(SIGINT, uloop_handle_signal, &old_sigint, add);
 401         uloop_install_handler(SIGTERM, uloop_handle_signal, &old_sigterm, add);
 402         uloop_install_handler(SIGQUIT, uloop_handle_signal, &old_sigterm, add);
 403         uloop_install_handler(SIGCHLD, uloop_handle_signal, &old_sigchld, add);
 404
 405         uloop_ignore_signal(SIGPIPE, add);
 406 }
 407
 408 static int uloop_get_next_timeout(struct timeval *tv)
 409 {
 410         struct uloop_timeout *timeout;
 411         int diff;
 412
 413         if (list_empty(&timeouts))
 414                 return -1;
 415
 416         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 417         diff = tv_diff(&timeout->time, tv);
 418         if (diff < 0)
 419                 return 0;
 420
 421         return diff;
 422 }
 423
 424 static void uloop_process_timeouts(struct timeval *tv)
 425 {
 426         struct uloop_timeout *t;
 427
 428         while (!list_empty(&timeouts)) {
 429                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 430
 431                 if (tv_diff(&t->time, tv) > 0)
 432                         break;
 433
 434                 uloop_timeout_cancel(t);
 435                 if (t->cb)
 436                         t->cb(t);
 437         }
 438 }
 439
 440 static void uloop_clear_timeouts(void)
 441 {
 442         struct uloop_timeout *t, *tmp;
 443
 444         list_for_each_entry_safe(t, tmp, &timeouts, list)
 445                 uloop_timeout_cancel(t);
 446 }
 447
 448 static void uloop_clear_processes(void)
 449 {
 450         struct uloop_process *p, *tmp;
 451
 452         list_for_each_entry_safe(p, tmp, &processes, list)
 453                 uloop_process_delete(p);
 454 }
 455
 456 void uloop_run(void)
 457 {
 458         static int recursive_calls = 0;
 459         struct timeval tv;
 460
 461         /*
 462          * Handlers are only updated for the first call to uloop_run() (and restored
 463          * when this call is done).
 464          */
 465         if (!recursive_calls++)
 466                 uloop_setup_signals(true);
 467
 468         uloop_cancelled = false;
 469         while(!uloop_cancelled)
 470         {
 471                 uloop_gettime(&tv);
 472                 uloop_process_timeouts(&tv);
 473
 474                 if (do_sigchld)
 475                         uloop_handle_processes();
 476
 477                 if (uloop_cancelled)
 478                         break;
 479
 480                 uloop_gettime(&tv);
 481                 uloop_run_events(uloop_get_next_timeout(&tv));
 482         }
 483
 484         if (!--recursive_calls)
 485                 uloop_setup_signals(false);
 486 }
 487
 488 void uloop_done(void)
 489 {
 490         if (signal_fd >= 0) {
 491                 close(signal_fd);
 492                 signal_fd = -1;
 493         }
 494
 495         if (poll_fd < 0)
 496                 return;
 497
 498         close(poll_fd);
 499         poll_fd = -1;
 500
 501         uloop_clear_timeouts();
 502         uloop_clear_processes();
 503 }