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 poll_fd = -1;
  60 bool uloop_cancelled = false;
  61 bool uloop_handle_sigchld = true;
  62 static int uloop_status = 0;
  63 static bool do_sigchld = false;
  64
  65 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  66 static int cur_fd, cur_nfds;
  67 static int uloop_run_depth = 0;
  68
  69 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  70
  71 #ifdef USE_KQUEUE
  72 #include "uloop-kqueue.c"
  73 #endif
  74
  75 #ifdef USE_EPOLL
  76 #include "uloop-epoll.c"
  77 #endif
  78
  79 static void waker_consume(struct uloop_fd *fd, unsigned int events)
  80 {
  81         char buf[4];
  82
  83         while (read(fd->fd, buf, 4) > 0)
  84                 ;
  85 }
  86
  87 static int waker_pipe = -1;
  88 static struct uloop_fd waker_fd = {
  89         .fd = -1,
  90         .cb = waker_consume,
  91 };
  92
  93 static void waker_init_fd(int fd)
  94 {
  95         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
  96         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
  97 }
  98
  99 static int waker_init(void)
 100 {
 101         int fds[2];
 102
 103         if (waker_pipe >= 0)
 104                 return 0;
 105
 106         if (pipe(fds) < 0)
 107                 return -1;
 108
 109         waker_init_fd(fds[0]);
 110         waker_init_fd(fds[1]);
 111         waker_pipe = fds[1];
 112
 113         waker_fd.fd = fds[0];
 114         waker_fd.cb = waker_consume;
 115         uloop_fd_add(&waker_fd, ULOOP_READ);
 116
 117         return 0;
 118 }
 119
 120 static void uloop_setup_signals(bool add);
 121
 122 int uloop_init(void)
 123 {
 124         if (uloop_init_pollfd() < 0)
 125                 return -1;
 126
 127         if (waker_init() < 0) {
 128                 uloop_done();
 129                 return -1;
 130         }
 131
 132         uloop_setup_signals(true);
 133
 134         return 0;
 135 }
 136
 137 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 138 {
 139         struct uloop_fd_stack *cur;
 140
 141         /*
 142          * Do not buffer events for level-triggered fds, they will keep firing.
 143          * Caller needs to take care of recursion issues.
 144          */
 145         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 146                 return false;
 147
 148         for (cur = fd_stack; cur; cur = cur->next) {
 149                 if (cur->fd != fd)
 150                         continue;
 151
 152                 if (events < 0)
 153                         cur->fd = NULL;
 154                 else
 155                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 156
 157                 return true;
 158         }
 159
 160         return false;
 161 }
 162
 163 static void uloop_run_events(int timeout)
 164 {
 165         struct uloop_fd_event *cur;
 166         struct uloop_fd *fd;
 167
 168         if (!cur_nfds) {
 169                 cur_fd = 0;
 170                 cur_nfds = uloop_fetch_events(timeout);
 171                 if (cur_nfds < 0)
 172                         cur_nfds = 0;
 173         }
 174
 175         while (cur_nfds > 0) {
 176                 struct uloop_fd_stack stack_cur;
 177                 unsigned int events;
 178
 179                 cur = &cur_fds[cur_fd++];
 180                 cur_nfds--;
 181
 182                 fd = cur->fd;
 183                 events = cur->events;
 184                 if (!fd)
 185                         continue;
 186
 187                 if (!fd->cb)
 188                         continue;
 189
 190                 if (uloop_fd_stack_event(fd, cur->events))
 191                         continue;
 192
 193                 stack_cur.next = fd_stack;
 194                 stack_cur.fd = fd;
 195                 fd_stack = &stack_cur;
 196                 do {
 197                         stack_cur.events = 0;
 198                         fd->cb(fd, events);
 199                         events = stack_cur.events & ULOOP_EVENT_MASK;
 200                 } while (stack_cur.fd && events);
 201                 fd_stack = stack_cur.next;
 202
 203                 return;
 204         }
 205 }
 206
 207 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 208 {
 209         unsigned int fl;
 210         int ret;
 211
 212         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 213                 return uloop_fd_delete(sock);
 214
 215         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 216                 fl = fcntl(sock->fd, F_GETFL, 0);
 217                 fl |= O_NONBLOCK;
 218                 fcntl(sock->fd, F_SETFL, fl);
 219         }
 220
 221         ret = register_poll(sock, flags);
 222         if (ret < 0)
 223                 goto out;
 224
 225         sock->registered = true;
 226         sock->eof = false;
 227         sock->error = false;
 228
 229 out:
 230         return ret;
 231 }
 232
 233 int uloop_fd_delete(struct uloop_fd *fd)
 234 {
 235         int i;
 236
 237         for (i = 0; i < cur_nfds; i++) {
 238                 if (cur_fds[cur_fd + i].fd != fd)
 239                         continue;
 240
 241                 cur_fds[cur_fd + i].fd = NULL;
 242         }
 243
 244         if (!fd->registered)
 245                 return 0;
 246
 247         fd->registered = false;
 248         uloop_fd_stack_event(fd, -1);
 249         return __uloop_fd_delete(fd);
 250 }
 251
 252 static int tv_diff(struct timeval *t1, struct timeval *t2)
 253 {
 254         return
 255                 (t1->tv_sec - t2->tv_sec) * 1000 +
 256                 (t1->tv_usec - t2->tv_usec) / 1000;
 257 }
 258
 259 int uloop_timeout_add(struct uloop_timeout *timeout)
 260 {
 261         struct uloop_timeout *tmp;
 262         struct list_head *h = &timeouts;
 263
 264         if (timeout->pending)
 265                 return -1;
 266
 267         list_for_each_entry(tmp, &timeouts, list) {
 268                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 269                         h = &tmp->list;
 270                         break;
 271                 }
 272         }
 273
 274         list_add_tail(&timeout->list, h);
 275         timeout->pending = true;
 276
 277         return 0;
 278 }
 279
 280 static void uloop_gettime(struct timeval *tv)
 281 {
 282         struct timespec ts;
 283
 284         clock_gettime(CLOCK_MONOTONIC, &ts);
 285         tv->tv_sec = ts.tv_sec;
 286         tv->tv_usec = ts.tv_nsec / 1000;
 287 }
 288
 289 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 290 {
 291         struct timeval *time = &timeout->time;
 292
 293         if (timeout->pending)
 294                 uloop_timeout_cancel(timeout);
 295
 296         uloop_gettime(time);
 297
 298         time->tv_sec += msecs / 1000;
 299         time->tv_usec += (msecs % 1000) * 1000;
 300
 301         if (time->tv_usec > 1000000) {
 302                 time->tv_sec++;
 303                 time->tv_usec -= 1000000;
 304         }
 305
 306         return uloop_timeout_add(timeout);
 307 }
 308
 309 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 310 {
 311         if (!timeout->pending)
 312                 return -1;
 313
 314         list_del(&timeout->list);
 315         timeout->pending = false;
 316
 317         return 0;
 318 }
 319
 320 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 321 {
 322         struct timeval now;
 323
 324         if (!timeout->pending)
 325                 return -1;
 326
 327         uloop_gettime(&now);
 328
 329         return tv_diff(&timeout->time, &now);
 330 }
 331
 332 int uloop_process_add(struct uloop_process *p)
 333 {
 334         struct uloop_process *tmp;
 335         struct list_head *h = &processes;
 336
 337         if (p->pending)
 338                 return -1;
 339
 340         list_for_each_entry(tmp, &processes, list) {
 341                 if (tmp->pid > p->pid) {
 342                         h = &tmp->list;
 343                         break;
 344                 }
 345         }
 346
 347         list_add_tail(&p->list, h);
 348         p->pending = true;
 349
 350         return 0;
 351 }
 352
 353 int uloop_process_delete(struct uloop_process *p)
 354 {
 355         if (!p->pending)
 356                 return -1;
 357
 358         list_del(&p->list);
 359         p->pending = false;
 360
 361         return 0;
 362 }
 363
 364 static void uloop_handle_processes(void)
 365 {
 366         struct uloop_process *p, *tmp;
 367         pid_t pid;
 368         int ret;
 369
 370         do_sigchld = false;
 371
 372         while (1) {
 373                 pid = waitpid(-1, &ret, WNOHANG);
 374                 if (pid < 0 && errno == EINTR)
 375                         continue;
 376
 377                 if (pid <= 0)
 378                         return;
 379
 380                 list_for_each_entry_safe(p, tmp, &processes, list) {
 381                         if (p->pid < pid)
 382                                 continue;
 383
 384                         if (p->pid > pid)
 385                                 break;
 386
 387                         uloop_process_delete(p);
 388                         p->cb(p, ret);
 389                 }
 390         }
 391
 392 }
 393
 394 static void uloop_signal_wake(void)
 395 {
 396         do {
 397                 if (write(waker_pipe, "w", 1) < 0) {
 398                         if (errno == EINTR)
 399                                 continue;
 400                 }
 401                 break;
 402         } while (1);
 403 }
 404
 405 static void uloop_handle_sigint(int signo)
 406 {
 407         uloop_status = signo;
 408         uloop_cancelled = true;
 409         uloop_signal_wake();
 410 }
 411
 412 static void uloop_sigchld(int signo)
 413 {
 414         do_sigchld = true;
 415         uloop_signal_wake();
 416 }
 417
 418 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 419 {
 420         struct sigaction s;
 421         struct sigaction *act;
 422
 423         act = NULL;
 424         sigaction(signum, NULL, &s);
 425
 426         if (add) {
 427                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 428                         memcpy(old, &s, sizeof(struct sigaction));
 429                         s.sa_handler = handler;
 430                         s.sa_flags = 0;
 431                         act = &s;
 432                 }
 433         }
 434         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 435                         act = old;
 436         }
 437
 438         if (act != NULL)
 439                 sigaction(signum, act, NULL);
 440 }
 441
 442 static void uloop_ignore_signal(int signum, bool ignore)
 443 {
 444         struct sigaction s;
 445         void *new_handler = NULL;
 446
 447         sigaction(signum, NULL, &s);
 448
 449         if (ignore) {
 450                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 451                         new_handler = SIG_IGN;
 452         } else {
 453                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 454                         new_handler = SIG_DFL;
 455         }
 456
 457         if (new_handler) {
 458                 s.sa_handler = new_handler;
 459                 s.sa_flags = 0;
 460                 sigaction(signum, &s, NULL);
 461         }
 462 }
 463
 464 static void uloop_setup_signals(bool add)
 465 {
 466         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 467
 468         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 469         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 470
 471         if (uloop_handle_sigchld)
 472                 uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 473
 474         uloop_ignore_signal(SIGPIPE, add);
 475 }
 476
 477 static int uloop_get_next_timeout(struct timeval *tv)
 478 {
 479         struct uloop_timeout *timeout;
 480         int diff;
 481
 482         if (list_empty(&timeouts))
 483                 return -1;
 484
 485         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 486         diff = tv_diff(&timeout->time, tv);
 487         if (diff < 0)
 488                 return 0;
 489
 490         return diff;
 491 }
 492
 493 static void uloop_process_timeouts(struct timeval *tv)
 494 {
 495         struct uloop_timeout *t;
 496
 497         while (!list_empty(&timeouts)) {
 498                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 499
 500                 if (tv_diff(&t->time, tv) > 0)
 501                         break;
 502
 503                 uloop_timeout_cancel(t);
 504                 if (t->cb)
 505                         t->cb(t);
 506         }
 507 }
 508
 509 static void uloop_clear_timeouts(void)
 510 {
 511         struct uloop_timeout *t, *tmp;
 512
 513         list_for_each_entry_safe(t, tmp, &timeouts, list)
 514                 uloop_timeout_cancel(t);
 515 }
 516
 517 static void uloop_clear_processes(void)
 518 {
 519         struct uloop_process *p, *tmp;
 520
 521         list_for_each_entry_safe(p, tmp, &processes, list)
 522                 uloop_process_delete(p);
 523 }
 524
 525 bool uloop_cancelling(void)
 526 {
 527         return uloop_run_depth > 0 && uloop_cancelled;
 528 }
 529
 530 int uloop_run_timeout(int timeout)
 531 {
 532         int next_time = 0;
 533         struct timeval tv;
 534
 535         uloop_run_depth++;
 536
 537         uloop_status = 0;
 538         uloop_cancelled = false;
 539         while (!uloop_cancelled)
 540         {
 541                 uloop_gettime(&tv);
 542                 uloop_process_timeouts(&tv);
 543
 544                 if (do_sigchld)
 545                         uloop_handle_processes();
 546
 547                 if (uloop_cancelled)
 548                         break;
 549
 550                 uloop_gettime(&tv);
 551
 552                 next_time = uloop_get_next_timeout(&tv);
 553                 if (timeout >= 0 && timeout < next_time)
 554                         next_time = timeout;
 555                 uloop_run_events(next_time);
 556         }
 557
 558         --uloop_run_depth;
 559
 560         return uloop_status;
 561 }
 562
 563 void uloop_done(void)
 564 {
 565         uloop_setup_signals(false);
 566
 567         if (poll_fd >= 0) {
 568                 close(poll_fd);
 569                 poll_fd = -1;
 570         }
 571
 572         if (waker_pipe >= 0) {
 573                 uloop_fd_delete(&waker_fd);
 574                 close(waker_pipe);
 575                 close(waker_fd.fd);
 576                 waker_pipe = -1;
 577         }
 578
 579         uloop_clear_timeouts();
 580         uloop_clear_processes();
 581 }