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 static struct list_head signals = LIST_HEAD_INIT(signals);
  61
  62 static int poll_fd = -1;
  63 bool uloop_cancelled = false;
  64 bool uloop_handle_sigchld = true;
  65 static int uloop_status = 0;
  66 static bool do_sigchld = false;
  67
  68 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  69 static int cur_fd, cur_nfds;
  70 static int uloop_run_depth = 0;
  71
  72 uloop_fd_handler uloop_fd_set_cb = NULL;
  73
  74 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  75
  76 #ifdef USE_KQUEUE
  77 #include "uloop-kqueue.c"
  78 #endif
  79
  80 #ifdef USE_EPOLL
  81 #include "uloop-epoll.c"
  82 #endif
  83
  84 static void set_signo(uint64_t *signums, int signo)
  85 {
  86         if (signo >= 1 && signo <= 64)
  87                 *signums |= (1u << (signo - 1));
  88 }
  89
  90 static bool get_signo(uint64_t signums, int signo)
  91 {
  92         return (signo >= 1) && (signo <= 64) && (signums & (1u << (signo - 1)));
  93 }
  94
  95 static void signal_consume(struct uloop_fd *fd, unsigned int events)
  96 {
  97         struct uloop_signal *usig, *usig_next;
  98         uint64_t signums = 0;
  99         uint8_t buf[32];
 100         ssize_t nsigs;
 101
 102         do {
 103                 nsigs = read(fd->fd, buf, sizeof(buf));
 104
 105                 for (ssize_t i = 0; i < nsigs; i++)
 106                         set_signo(&signums, buf[i]);
 107         }
 108         while (nsigs > 0);
 109
 110         list_for_each_entry_safe(usig, usig_next, &signals, list)
 111                 if (get_signo(signums, usig->signo))
 112                         usig->cb(usig);
 113 }
 114
 115 static int waker_pipe = -1;
 116 static struct uloop_fd waker_fd = {
 117         .fd = -1,
 118         .cb = signal_consume,
 119 };
 120
 121 static void waker_init_fd(int fd)
 122 {
 123         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 124         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
 125 }
 126
 127 static int waker_init(void)
 128 {
 129         int fds[2];
 130
 131         if (waker_pipe >= 0)
 132                 return 0;
 133
 134         if (pipe(fds) < 0)
 135                 return -1;
 136
 137         waker_init_fd(fds[0]);
 138         waker_init_fd(fds[1]);
 139         waker_pipe = fds[1];
 140
 141         waker_fd.fd = fds[0];
 142         waker_fd.cb = signal_consume;
 143         uloop_fd_add(&waker_fd, ULOOP_READ);
 144
 145         return 0;
 146 }
 147
 148 static void uloop_setup_signals(bool add);
 149
 150 int uloop_init(void)
 151 {
 152         if (uloop_init_pollfd() < 0)
 153                 return -1;
 154
 155         if (waker_init() < 0) {
 156                 uloop_done();
 157                 return -1;
 158         }
 159
 160         uloop_setup_signals(true);
 161
 162         return 0;
 163 }
 164
 165 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 166 {
 167         struct uloop_fd_stack *cur;
 168
 169         /*
 170          * Do not buffer events for level-triggered fds, they will keep firing.
 171          * Caller needs to take care of recursion issues.
 172          */
 173         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 174                 return false;
 175
 176         for (cur = fd_stack; cur; cur = cur->next) {
 177                 if (cur->fd != fd)
 178                         continue;
 179
 180                 if (events < 0)
 181                         cur->fd = NULL;
 182                 else
 183                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 184
 185                 return true;
 186         }
 187
 188         return false;
 189 }
 190
 191 static void uloop_run_events(int64_t timeout)
 192 {
 193         struct uloop_fd_event *cur;
 194         struct uloop_fd *fd;
 195
 196         if (!cur_nfds) {
 197                 cur_fd = 0;
 198                 cur_nfds = uloop_fetch_events(timeout);
 199                 if (cur_nfds < 0)
 200                         cur_nfds = 0;
 201         }
 202
 203         while (cur_nfds > 0) {
 204                 struct uloop_fd_stack stack_cur;
 205                 unsigned int events;
 206
 207                 cur = &cur_fds[cur_fd++];
 208                 cur_nfds--;
 209
 210                 fd = cur->fd;
 211                 events = cur->events;
 212                 if (!fd)
 213                         continue;
 214
 215                 if (!fd->cb)
 216                         continue;
 217
 218                 if (uloop_fd_stack_event(fd, cur->events))
 219                         continue;
 220
 221                 stack_cur.next = fd_stack;
 222                 stack_cur.fd = fd;
 223                 fd_stack = &stack_cur;
 224                 do {
 225                         stack_cur.events = 0;
 226                         fd->cb(fd, events);
 227                         events = stack_cur.events & ULOOP_EVENT_MASK;
 228                 } while (stack_cur.fd && events);
 229                 fd_stack = stack_cur.next;
 230
 231                 return;
 232         }
 233 }
 234
 235 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 236 {
 237         unsigned int fl;
 238         int ret;
 239
 240         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 241                 return uloop_fd_delete(sock);
 242
 243         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 244                 fl = fcntl(sock->fd, F_GETFL, 0);
 245                 fl |= O_NONBLOCK;
 246                 fcntl(sock->fd, F_SETFL, fl);
 247         }
 248
 249         ret = register_poll(sock, flags);
 250         if (ret < 0)
 251                 goto out;
 252
 253         if (uloop_fd_set_cb)
 254                 uloop_fd_set_cb(sock, flags);
 255
 256         sock->flags = flags;
 257         sock->registered = true;
 258         sock->eof = false;
 259         sock->error = false;
 260
 261 out:
 262         return ret;
 263 }
 264
 265 int uloop_fd_delete(struct uloop_fd *fd)
 266 {
 267         int ret;
 268         int i;
 269
 270         for (i = 0; i < cur_nfds; i++) {
 271                 if (cur_fds[cur_fd + i].fd != fd)
 272                         continue;
 273
 274                 cur_fds[cur_fd + i].fd = NULL;
 275         }
 276
 277         if (!fd->registered)
 278                 return 0;
 279
 280         if (uloop_fd_set_cb)
 281                 uloop_fd_set_cb(fd, 0);
 282
 283         fd->registered = false;
 284         uloop_fd_stack_event(fd, -1);
 285         ret = __uloop_fd_delete(fd);
 286         fd->flags = 0;
 287
 288         return ret;
 289 }
 290
 291 static int64_t tv_diff(struct timeval *t1, struct timeval *t2)
 292 {
 293         return
 294                 (t1->tv_sec - t2->tv_sec) * 1000 +
 295                 (t1->tv_usec - t2->tv_usec) / 1000;
 296 }
 297
 298 int uloop_timeout_add(struct uloop_timeout *timeout)
 299 {
 300         struct uloop_timeout *tmp;
 301         struct list_head *h = &timeouts;
 302
 303         if (timeout->pending)
 304                 return -1;
 305
 306         list_for_each_entry(tmp, &timeouts, list) {
 307                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 308                         h = &tmp->list;
 309                         break;
 310                 }
 311         }
 312
 313         list_add_tail(&timeout->list, h);
 314         timeout->pending = true;
 315
 316         return 0;
 317 }
 318
 319 static void uloop_gettime(struct timeval *tv)
 320 {
 321         struct timespec ts;
 322
 323         clock_gettime(CLOCK_MONOTONIC, &ts);
 324         tv->tv_sec = ts.tv_sec;
 325         tv->tv_usec = ts.tv_nsec / 1000;
 326 }
 327
 328 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 329 {
 330         struct timeval *time = &timeout->time;
 331
 332         if (timeout->pending)
 333                 uloop_timeout_cancel(timeout);
 334
 335         uloop_gettime(time);
 336
 337         time->tv_sec += msecs / 1000;
 338         time->tv_usec += (msecs % 1000) * 1000;
 339
 340         if (time->tv_usec > 1000000) {
 341                 time->tv_sec++;
 342                 time->tv_usec -= 1000000;
 343         }
 344
 345         return uloop_timeout_add(timeout);
 346 }
 347
 348 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 349 {
 350         if (!timeout->pending)
 351                 return -1;
 352
 353         list_del(&timeout->list);
 354         timeout->pending = false;
 355
 356         return 0;
 357 }
 358
 359 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 360 {
 361         int64_t td;
 362         struct timeval now;
 363
 364         if (!timeout->pending)
 365                 return -1;
 366
 367         uloop_gettime(&now);
 368
 369         td = tv_diff(&timeout->time, &now);
 370
 371         if (td > INT_MAX)
 372                 return INT_MAX;
 373         else if (td < INT_MIN)
 374                 return INT_MIN;
 375         else
 376                 return (int)td;
 377 }
 378
 379 int64_t uloop_timeout_remaining64(struct uloop_timeout *timeout)
 380 {
 381         struct timeval now;
 382
 383         if (!timeout->pending)
 384                 return -1;
 385
 386         uloop_gettime(&now);
 387
 388         return tv_diff(&timeout->time, &now);
 389 }
 390
 391 int uloop_process_add(struct uloop_process *p)
 392 {
 393         struct uloop_process *tmp;
 394         struct list_head *h = &processes;
 395
 396         if (p->pending)
 397                 return -1;
 398
 399         list_for_each_entry(tmp, &processes, list) {
 400                 if (tmp->pid > p->pid) {
 401                         h = &tmp->list;
 402                         break;
 403                 }
 404         }
 405
 406         list_add_tail(&p->list, h);
 407         p->pending = true;
 408
 409         return 0;
 410 }
 411
 412 int uloop_process_delete(struct uloop_process *p)
 413 {
 414         if (!p->pending)
 415                 return -1;
 416
 417         list_del(&p->list);
 418         p->pending = false;
 419
 420         return 0;
 421 }
 422
 423 static void uloop_handle_processes(void)
 424 {
 425         struct uloop_process *p, *tmp;
 426         pid_t pid;
 427         int ret;
 428
 429         do_sigchld = false;
 430
 431         while (1) {
 432                 pid = waitpid(-1, &ret, WNOHANG);
 433                 if (pid < 0 && errno == EINTR)
 434                         continue;
 435
 436                 if (pid <= 0)
 437                         return;
 438
 439                 list_for_each_entry_safe(p, tmp, &processes, list) {
 440                         if (p->pid < pid)
 441                                 continue;
 442
 443                         if (p->pid > pid)
 444                                 break;
 445
 446                         uloop_process_delete(p);
 447                         p->cb(p, ret);
 448                 }
 449         }
 450
 451 }
 452
 453 int uloop_interval_set(struct uloop_interval *timer, unsigned int msecs)
 454 {
 455         return timer_register(timer, msecs);
 456 }
 457
 458 int uloop_interval_cancel(struct uloop_interval *timer)
 459 {
 460         return timer_remove(timer);
 461 }
 462
 463 int64_t uloop_interval_remaining(struct uloop_interval *timer)
 464 {
 465         return timer_next(timer);
 466 }
 467
 468 static void uloop_signal_wake(int signo)
 469 {
 470         uint8_t sigbyte = signo;
 471
 472         if (signo == SIGCHLD)
 473                 do_sigchld = true;
 474
 475         do {
 476                 if (write(waker_pipe, &sigbyte, 1) < 0) {
 477                         if (errno == EINTR)
 478                                 continue;
 479                 }
 480                 break;
 481         } while (1);
 482 }
 483
 484 static void uloop_handle_sigint(int signo)
 485 {
 486         uloop_status = signo;
 487         uloop_cancelled = true;
 488         uloop_signal_wake(signo);
 489 }
 490
 491 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 492 {
 493         struct sigaction s;
 494         struct sigaction *act;
 495
 496         act = NULL;
 497         sigaction(signum, NULL, &s);
 498
 499         if (add) {
 500                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 501                         memcpy(old, &s, sizeof(struct sigaction));
 502                         s.sa_handler = handler;
 503                         s.sa_flags = 0;
 504                         act = &s;
 505                 }
 506         }
 507         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 508                         act = old;
 509         }
 510
 511         if (act != NULL)
 512                 sigaction(signum, act, NULL);
 513 }
 514
 515 static void uloop_ignore_signal(int signum, bool ignore)
 516 {
 517         struct sigaction s;
 518         void *new_handler = NULL;
 519
 520         sigaction(signum, NULL, &s);
 521
 522         if (ignore) {
 523                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 524                         new_handler = SIG_IGN;
 525         } else {
 526                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 527                         new_handler = SIG_DFL;
 528         }
 529
 530         if (new_handler) {
 531                 s.sa_handler = new_handler;
 532                 s.sa_flags = 0;
 533                 sigaction(signum, &s, NULL);
 534         }
 535 }
 536
 537 static void uloop_setup_signals(bool add)
 538 {
 539         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 540
 541         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 542         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 543
 544         if (uloop_handle_sigchld)
 545                 uloop_install_handler(SIGCHLD, uloop_signal_wake, &old_sigchld, add);
 546
 547         uloop_ignore_signal(SIGPIPE, add);
 548 }
 549
 550 int uloop_signal_add(struct uloop_signal *s)
 551 {
 552         struct list_head *h = &signals;
 553         struct uloop_signal *tmp;
 554         struct sigaction sa;
 555
 556         if (s->pending)
 557                 return -1;
 558
 559         list_for_each_entry(tmp, &signals, list) {
 560                 if (tmp->signo > s->signo) {
 561                         h = &tmp->list;
 562                         break;
 563                 }
 564         }
 565
 566         list_add_tail(&s->list, h);
 567         s->pending = true;
 568
 569         sigaction(s->signo, NULL, &s->orig);
 570
 571         if (s->orig.sa_handler != uloop_signal_wake) {
 572                 sa.sa_handler = uloop_signal_wake;
 573                 sa.sa_flags = 0;
 574                 sigemptyset(&sa.sa_mask);
 575                 sigaction(s->signo, &sa, NULL);
 576         }
 577
 578         return 0;
 579 }
 580
 581 int uloop_signal_delete(struct uloop_signal *s)
 582 {
 583         if (!s->pending)
 584                 return -1;
 585
 586         list_del(&s->list);
 587         s->pending = false;
 588
 589         if (s->orig.sa_handler != uloop_signal_wake)
 590                 sigaction(s->signo, &s->orig, NULL);
 591
 592         return 0;
 593 }
 594
 595 int uloop_get_next_timeout(void)
 596 {
 597         struct uloop_timeout *timeout;
 598         struct timeval tv;
 599         int64_t diff;
 600
 601         if (list_empty(&timeouts))
 602                 return -1;
 603
 604         uloop_gettime(&tv);
 605
 606         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 607         diff = tv_diff(&timeout->time, &tv);
 608         if (diff < 0)
 609                 return 0;
 610         if (diff > INT_MAX)
 611                 return INT_MAX;
 612
 613         return diff;
 614 }
 615
 616 static void uloop_process_timeouts(void)
 617 {
 618         struct uloop_timeout *t;
 619         struct timeval tv;
 620
 621         if (list_empty(&timeouts))
 622                 return;
 623
 624         uloop_gettime(&tv);
 625         while (!list_empty(&timeouts)) {
 626                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 627
 628                 if (tv_diff(&t->time, &tv) > 0)
 629                         break;
 630
 631                 uloop_timeout_cancel(t);
 632                 if (t->cb)
 633                         t->cb(t);
 634         }
 635 }
 636
 637 static void uloop_clear_timeouts(void)
 638 {
 639         struct uloop_timeout *t, *tmp;
 640
 641         list_for_each_entry_safe(t, tmp, &timeouts, list)
 642                 uloop_timeout_cancel(t);
 643 }
 644
 645 static void uloop_clear_processes(void)
 646 {
 647         struct uloop_process *p, *tmp;
 648
 649         list_for_each_entry_safe(p, tmp, &processes, list)
 650                 uloop_process_delete(p);
 651 }
 652
 653 bool uloop_cancelling(void)
 654 {
 655         return uloop_run_depth > 0 && uloop_cancelled;
 656 }
 657
 658 int uloop_run_timeout(int timeout)
 659 {
 660         int next_time = 0;
 661
 662         uloop_run_depth++;
 663
 664         uloop_status = 0;
 665         uloop_cancelled = false;
 666         do {
 667                 uloop_process_timeouts();
 668
 669                 if (do_sigchld)
 670                         uloop_handle_processes();
 671
 672                 if (uloop_cancelled)
 673                         break;
 674
 675                 next_time = uloop_get_next_timeout();
 676                 if (timeout >= 0 && (next_time < 0 || timeout < next_time))
 677                                 next_time = timeout;
 678                 uloop_run_events(next_time);
 679         } while (!uloop_cancelled && timeout < 0);
 680
 681         --uloop_run_depth;
 682
 683         return uloop_status;
 684 }
 685
 686 void uloop_done(void)
 687 {
 688         uloop_setup_signals(false);
 689
 690         if (poll_fd >= 0) {
 691                 close(poll_fd);
 692                 poll_fd = -1;
 693         }
 694
 695         if (waker_pipe >= 0) {
 696                 uloop_fd_delete(&waker_fd);
 697                 close(waker_pipe);
 698                 close(waker_fd.fd);
 699                 waker_pipe = -1;
 700         }
 701
 702         uloop_clear_timeouts();
 703         uloop_clear_processes();
 704 }