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 #include <limits.h>
  30
  31 #include "uloop.h"
  32 #include "utils.h"
  33
  34 #ifdef USE_KQUEUE
  35 #include <sys/event.h>
  36 #endif
  37 #ifdef USE_EPOLL
  38 #include <sys/epoll.h>
  39 #include <sys/timerfd.h>
  40 #endif
  41 #include <sys/wait.h>
  42
  43 struct uloop_fd_event {
  44         struct uloop_fd *fd;
  45         unsigned int events;
  46 };
  47
  48 struct uloop_fd_stack {
  49         struct uloop_fd_stack *next;
  50         struct uloop_fd *fd;
  51         unsigned int events;
  52 };
  53
  54 static struct uloop_fd_stack *fd_stack = NULL;
  55
  56 #define ULOOP_MAX_EVENTS 10
  57
  58 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
  59 static struct list_head processes = LIST_HEAD_INIT(processes);
  60
  61 static int poll_fd = -1;
  62 bool uloop_cancelled = false;
  63 bool uloop_handle_sigchld = true;
  64 static int uloop_status = 0;
  65 static bool do_sigchld = false;
  66
  67 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  68 static int cur_fd, cur_nfds;
  69 static int uloop_run_depth = 0;
  70
  71 uloop_fd_handler uloop_fd_set_cb = NULL;
  72
  73 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  74
  75 #ifdef USE_KQUEUE
  76 #include "uloop-kqueue.c"
  77 #endif
  78
  79 #ifdef USE_EPOLL
  80 #include "uloop-epoll.c"
  81 #endif
  82
  83 static void waker_consume(struct uloop_fd *fd, unsigned int events)
  84 {
  85         char buf[4];
  86
  87         while (read(fd->fd, buf, 4) > 0)
  88                 ;
  89 }
  90
  91 static int waker_pipe = -1;
  92 static struct uloop_fd waker_fd = {
  93         .fd = -1,
  94         .cb = waker_consume,
  95 };
  96
  97 static void waker_init_fd(int fd)
  98 {
  99         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 100         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
 101 }
 102
 103 static int waker_init(void)
 104 {
 105         int fds[2];
 106
 107         if (waker_pipe >= 0)
 108                 return 0;
 109
 110         if (pipe(fds) < 0)
 111                 return -1;
 112
 113         waker_init_fd(fds[0]);
 114         waker_init_fd(fds[1]);
 115         waker_pipe = fds[1];
 116
 117         waker_fd.fd = fds[0];
 118         waker_fd.cb = waker_consume;
 119         uloop_fd_add(&waker_fd, ULOOP_READ);
 120
 121         return 0;
 122 }
 123
 124 static void uloop_setup_signals(bool add);
 125
 126 int uloop_init(void)
 127 {
 128         if (uloop_init_pollfd() < 0)
 129                 return -1;
 130
 131         if (waker_init() < 0) {
 132                 uloop_done();
 133                 return -1;
 134         }
 135
 136         uloop_setup_signals(true);
 137
 138         return 0;
 139 }
 140
 141 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 142 {
 143         struct uloop_fd_stack *cur;
 144
 145         /*
 146          * Do not buffer events for level-triggered fds, they will keep firing.
 147          * Caller needs to take care of recursion issues.
 148          */
 149         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 150                 return false;
 151
 152         for (cur = fd_stack; cur; cur = cur->next) {
 153                 if (cur->fd != fd)
 154                         continue;
 155
 156                 if (events < 0)
 157                         cur->fd = NULL;
 158                 else
 159                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 160
 161                 return true;
 162         }
 163
 164         return false;
 165 }
 166
 167 static void uloop_run_events(int64_t timeout)
 168 {
 169         struct uloop_fd_event *cur;
 170         struct uloop_fd *fd;
 171
 172         if (!cur_nfds) {
 173                 cur_fd = 0;
 174                 cur_nfds = uloop_fetch_events(timeout);
 175                 if (cur_nfds < 0)
 176                         cur_nfds = 0;
 177         }
 178
 179         while (cur_nfds > 0) {
 180                 struct uloop_fd_stack stack_cur;
 181                 unsigned int events;
 182
 183                 cur = &cur_fds[cur_fd++];
 184                 cur_nfds--;
 185
 186                 fd = cur->fd;
 187                 events = cur->events;
 188                 if (!fd)
 189                         continue;
 190
 191                 if (!fd->cb)
 192                         continue;
 193
 194                 if (uloop_fd_stack_event(fd, cur->events))
 195                         continue;
 196
 197                 stack_cur.next = fd_stack;
 198                 stack_cur.fd = fd;
 199                 fd_stack = &stack_cur;
 200                 do {
 201                         stack_cur.events = 0;
 202                         fd->cb(fd, events);
 203                         events = stack_cur.events & ULOOP_EVENT_MASK;
 204                 } while (stack_cur.fd && events);
 205                 fd_stack = stack_cur.next;
 206
 207                 return;
 208         }
 209 }
 210
 211 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 212 {
 213         unsigned int fl;
 214         int ret;
 215
 216         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 217                 return uloop_fd_delete(sock);
 218
 219         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 220                 fl = fcntl(sock->fd, F_GETFL, 0);
 221                 fl |= O_NONBLOCK;
 222                 fcntl(sock->fd, F_SETFL, fl);
 223         }
 224
 225         ret = register_poll(sock, flags);
 226         if (ret < 0)
 227                 goto out;
 228
 229         if (uloop_fd_set_cb)
 230                 uloop_fd_set_cb(sock, flags);
 231
 232         sock->flags = flags;
 233         sock->registered = true;
 234         sock->eof = false;
 235         sock->error = false;
 236
 237 out:
 238         return ret;
 239 }
 240
 241 int uloop_fd_delete(struct uloop_fd *fd)
 242 {
 243         int i;
 244
 245         for (i = 0; i < cur_nfds; i++) {
 246                 if (cur_fds[cur_fd + i].fd != fd)
 247                         continue;
 248
 249                 cur_fds[cur_fd + i].fd = NULL;
 250         }
 251
 252         if (!fd->registered)
 253                 return 0;
 254
 255         if (uloop_fd_set_cb)
 256                 uloop_fd_set_cb(fd, 0);
 257
 258         fd->registered = false;
 259         fd->flags = 0;
 260         uloop_fd_stack_event(fd, -1);
 261         return __uloop_fd_delete(fd);
 262 }
 263
 264 static int64_t tv_diff(struct timeval *t1, struct timeval *t2)
 265 {
 266         return
 267                 (t1->tv_sec - t2->tv_sec) * 1000 +
 268                 (t1->tv_usec - t2->tv_usec) / 1000;
 269 }
 270
 271 int uloop_timeout_add(struct uloop_timeout *timeout)
 272 {
 273         struct uloop_timeout *tmp;
 274         struct list_head *h = &timeouts;
 275
 276         if (timeout->pending)
 277                 return -1;
 278
 279         list_for_each_entry(tmp, &timeouts, list) {
 280                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 281                         h = &tmp->list;
 282                         break;
 283                 }
 284         }
 285
 286         list_add_tail(&timeout->list, h);
 287         timeout->pending = true;
 288
 289         return 0;
 290 }
 291
 292 static void uloop_gettime(struct timeval *tv)
 293 {
 294         struct timespec ts;
 295
 296         clock_gettime(CLOCK_MONOTONIC, &ts);
 297         tv->tv_sec = ts.tv_sec;
 298         tv->tv_usec = ts.tv_nsec / 1000;
 299 }
 300
 301 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 302 {
 303         struct timeval *time = &timeout->time;
 304
 305         if (timeout->pending)
 306                 uloop_timeout_cancel(timeout);
 307
 308         uloop_gettime(time);
 309
 310         time->tv_sec += msecs / 1000;
 311         time->tv_usec += (msecs % 1000) * 1000;
 312
 313         if (time->tv_usec > 1000000) {
 314                 time->tv_sec++;
 315                 time->tv_usec -= 1000000;
 316         }
 317
 318         return uloop_timeout_add(timeout);
 319 }
 320
 321 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 322 {
 323         if (!timeout->pending)
 324                 return -1;
 325
 326         list_del(&timeout->list);
 327         timeout->pending = false;
 328
 329         return 0;
 330 }
 331
 332 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 333 {
 334         int64_t td;
 335         struct timeval now;
 336
 337         if (!timeout->pending)
 338                 return -1;
 339
 340         uloop_gettime(&now);
 341
 342         td = tv_diff(&timeout->time, &now);
 343
 344         if (td > INT_MAX)
 345                 return INT_MAX;
 346         else if (td < INT_MIN)
 347                 return INT_MIN;
 348         else
 349                 return (int)td;
 350 }
 351
 352 int64_t uloop_timeout_remaining64(struct uloop_timeout *timeout)
 353 {
 354         struct timeval now;
 355
 356         if (!timeout->pending)
 357                 return -1;
 358
 359         uloop_gettime(&now);
 360
 361         return tv_diff(&timeout->time, &now);
 362 }
 363
 364 int uloop_process_add(struct uloop_process *p)
 365 {
 366         struct uloop_process *tmp;
 367         struct list_head *h = &processes;
 368
 369         if (p->pending)
 370                 return -1;
 371
 372         list_for_each_entry(tmp, &processes, list) {
 373                 if (tmp->pid > p->pid) {
 374                         h = &tmp->list;
 375                         break;
 376                 }
 377         }
 378
 379         list_add_tail(&p->list, h);
 380         p->pending = true;
 381
 382         return 0;
 383 }
 384
 385 int uloop_process_delete(struct uloop_process *p)
 386 {
 387         if (!p->pending)
 388                 return -1;
 389
 390         list_del(&p->list);
 391         p->pending = false;
 392
 393         return 0;
 394 }
 395
 396 static void uloop_handle_processes(void)
 397 {
 398         struct uloop_process *p, *tmp;
 399         pid_t pid;
 400         int ret;
 401
 402         do_sigchld = false;
 403
 404         while (1) {
 405                 pid = waitpid(-1, &ret, WNOHANG);
 406                 if (pid < 0 && errno == EINTR)
 407                         continue;
 408
 409                 if (pid <= 0)
 410                         return;
 411
 412                 list_for_each_entry_safe(p, tmp, &processes, list) {
 413                         if (p->pid < pid)
 414                                 continue;
 415
 416                         if (p->pid > pid)
 417                                 break;
 418
 419                         uloop_process_delete(p);
 420                         p->cb(p, ret);
 421                 }
 422         }
 423
 424 }
 425
 426 int uloop_interval_set(struct uloop_interval *timer, unsigned int msecs)
 427 {
 428         return timer_register(timer, msecs);
 429 }
 430
 431 int uloop_interval_cancel(struct uloop_interval *timer)
 432 {
 433         return timer_remove(timer);
 434 }
 435
 436 int64_t uloop_interval_remaining(struct uloop_interval *timer)
 437 {
 438         return timer_next(timer);
 439 }
 440
 441 static void uloop_signal_wake(void)
 442 {
 443         do {
 444                 if (write(waker_pipe, "w", 1) < 0) {
 445                         if (errno == EINTR)
 446                                 continue;
 447                 }
 448                 break;
 449         } while (1);
 450 }
 451
 452 static void uloop_handle_sigint(int signo)
 453 {
 454         uloop_status = signo;
 455         uloop_cancelled = true;
 456         uloop_signal_wake();
 457 }
 458
 459 static void uloop_sigchld(int signo)
 460 {
 461         do_sigchld = true;
 462         uloop_signal_wake();
 463 }
 464
 465 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 466 {
 467         struct sigaction s;
 468         struct sigaction *act;
 469
 470         act = NULL;
 471         sigaction(signum, NULL, &s);
 472
 473         if (add) {
 474                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 475                         memcpy(old, &s, sizeof(struct sigaction));
 476                         s.sa_handler = handler;
 477                         s.sa_flags = 0;
 478                         act = &s;
 479                 }
 480         }
 481         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 482                         act = old;
 483         }
 484
 485         if (act != NULL)
 486                 sigaction(signum, act, NULL);
 487 }
 488
 489 static void uloop_ignore_signal(int signum, bool ignore)
 490 {
 491         struct sigaction s;
 492         void *new_handler = NULL;
 493
 494         sigaction(signum, NULL, &s);
 495
 496         if (ignore) {
 497                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 498                         new_handler = SIG_IGN;
 499         } else {
 500                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 501                         new_handler = SIG_DFL;
 502         }
 503
 504         if (new_handler) {
 505                 s.sa_handler = new_handler;
 506                 s.sa_flags = 0;
 507                 sigaction(signum, &s, NULL);
 508         }
 509 }
 510
 511 static void uloop_setup_signals(bool add)
 512 {
 513         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 514
 515         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 516         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 517
 518         if (uloop_handle_sigchld)
 519                 uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 520
 521         uloop_ignore_signal(SIGPIPE, add);
 522 }
 523
 524 int uloop_get_next_timeout(void)
 525 {
 526         struct uloop_timeout *timeout;
 527         struct timeval tv;
 528         int64_t diff;
 529
 530         if (list_empty(&timeouts))
 531                 return -1;
 532
 533         uloop_gettime(&tv);
 534
 535         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 536         diff = tv_diff(&timeout->time, &tv);
 537         if (diff < 0)
 538                 return 0;
 539         if (diff > INT_MAX)
 540                 return INT_MAX;
 541
 542         return diff;
 543 }
 544
 545 static void uloop_process_timeouts(void)
 546 {
 547         struct uloop_timeout *t;
 548         struct timeval tv;
 549
 550         if (list_empty(&timeouts))
 551                 return;
 552
 553         uloop_gettime(&tv);
 554         while (!list_empty(&timeouts)) {
 555                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 556
 557                 if (tv_diff(&t->time, &tv) > 0)
 558                         break;
 559
 560                 uloop_timeout_cancel(t);
 561                 if (t->cb)
 562                         t->cb(t);
 563         }
 564 }
 565
 566 static void uloop_clear_timeouts(void)
 567 {
 568         struct uloop_timeout *t, *tmp;
 569
 570         list_for_each_entry_safe(t, tmp, &timeouts, list)
 571                 uloop_timeout_cancel(t);
 572 }
 573
 574 static void uloop_clear_processes(void)
 575 {
 576         struct uloop_process *p, *tmp;
 577
 578         list_for_each_entry_safe(p, tmp, &processes, list)
 579                 uloop_process_delete(p);
 580 }
 581
 582 bool uloop_cancelling(void)
 583 {
 584         return uloop_run_depth > 0 && uloop_cancelled;
 585 }
 586
 587 int uloop_run_timeout(int timeout)
 588 {
 589         int next_time = 0;
 590
 591         uloop_run_depth++;
 592
 593         uloop_status = 0;
 594         uloop_cancelled = false;
 595         do {
 596                 uloop_process_timeouts();
 597
 598                 if (do_sigchld)
 599                         uloop_handle_processes();
 600
 601                 if (uloop_cancelled)
 602                         break;
 603
 604                 next_time = uloop_get_next_timeout();
 605                 if (timeout >= 0 && (next_time < 0 || timeout < next_time))
 606                                 next_time = timeout;
 607                 uloop_run_events(next_time);
 608         } while (!uloop_cancelled && timeout < 0);
 609
 610         --uloop_run_depth;
 611
 612         return uloop_status;
 613 }
 614
 615 void uloop_done(void)
 616 {
 617         uloop_setup_signals(false);
 618
 619         if (poll_fd >= 0) {
 620                 close(poll_fd);
 621                 poll_fd = -1;
 622         }
 623
 624         if (waker_pipe >= 0) {
 625                 uloop_fd_delete(&waker_fd);
 626                 close(waker_pipe);
 627                 close(waker_fd.fd);
 628                 waker_pipe = -1;
 629         }
 630
 631         uloop_clear_timeouts();
 632         uloop_clear_processes();
 633 }