uloop.c

   1 /*
   2  * uloop - event loop implementation
   3  *
   4  * Copyright (C) 2010-2013 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 static bool do_sigchld = false;
  62
  63 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  64 static int cur_fd, cur_nfds;
  65
  66 #ifdef USE_KQUEUE
  67
  68 int uloop_init(void)
  69 {
  70         struct timespec timeout = { 0, 0 };
  71         struct kevent ev = {};
  72
  73         if (poll_fd >= 0)
  74                 return 0;
  75
  76         poll_fd = kqueue();
  77         if (poll_fd < 0)
  78                 return -1;
  79
  80         EV_SET(&ev, SIGCHLD, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
  81         kevent(poll_fd, &ev, 1, NULL, 0, &timeout);
  82
  83         return 0;
  84 }
  85
  86
  87 static uint16_t get_flags(unsigned int flags, unsigned int mask)
  88 {
  89         uint16_t kflags = 0;
  90
  91         if (!(flags & mask))
  92                 return EV_DELETE;
  93
  94         kflags = EV_ADD;
  95         if (flags & ULOOP_EDGE_TRIGGER)
  96                 kflags |= EV_CLEAR;
  97
  98         return kflags;
  99 }
 100
 101 static struct kevent events[ULOOP_MAX_EVENTS];
 102
 103 static int register_kevent(struct uloop_fd *fd, unsigned int flags)
 104 {
 105         struct timespec timeout = { 0, 0 };
 106         struct kevent ev[2];
 107         int nev = 0;
 108         unsigned int fl = 0;
 109         unsigned int changed;
 110         uint16_t kflags;
 111
 112         if (flags & ULOOP_EDGE_DEFER)
 113                 flags &= ~ULOOP_EDGE_TRIGGER;
 114
 115         changed = flags ^ fd->flags;
 116         if (changed & ULOOP_EDGE_TRIGGER)
 117                 changed |= flags;
 118
 119         if (changed & ULOOP_READ) {
 120                 kflags = get_flags(flags, ULOOP_READ);
 121                 EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
 122         }
 123
 124         if (changed & ULOOP_WRITE) {
 125                 kflags = get_flags(flags, ULOOP_WRITE);
 126                 EV_SET(&ev[nev++], fd->fd, EVFILT_WRITE, kflags, 0, 0, fd);
 127         }
 128
 129         if (!flags)
 130                 fl |= EV_DELETE;
 131
 132         fd->flags = flags;
 133         if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
 134                 return -1;
 135
 136         return 0;
 137 }
 138
 139 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 140 {
 141         if (flags & ULOOP_EDGE_TRIGGER)
 142                 flags |= ULOOP_EDGE_DEFER;
 143         else
 144                 flags &= ~ULOOP_EDGE_DEFER;
 145
 146         return register_kevent(fd, flags);
 147 }
 148
 149 static int __uloop_fd_delete(struct uloop_fd *fd)
 150 {
 151         return register_poll(fd, 0);
 152 }
 153
 154 static int uloop_fetch_events(int timeout)
 155 {
 156         struct timespec ts;
 157         int nfds, n;
 158
 159         if (timeout >= 0) {
 160                 ts.tv_sec = timeout / 1000;
 161                 ts.tv_nsec = (timeout % 1000) * 1000000;
 162         }
 163
 164         nfds = kevent(poll_fd, NULL, 0, events, ARRAY_SIZE(events), timeout >= 0 ? &ts : NULL);
 165         for (n = 0; n < nfds; n++) {
 166                 struct uloop_fd_event *cur = &cur_fds[n];
 167                 struct uloop_fd *u = events[n].udata;
 168                 unsigned int ev = 0;
 169
 170                 cur->fd = u;
 171                 if (!u)
 172                         continue;
 173
 174                 if (events[n].flags & EV_ERROR) {
 175                         u->error = true;
 176                         if (!(u->flags & ULOOP_ERROR_CB))
 177                                 uloop_fd_delete(u);
 178                 }
 179
 180                 if(events[n].filter == EVFILT_READ)
 181                         ev |= ULOOP_READ;
 182                 else if (events[n].filter == EVFILT_WRITE)
 183                         ev |= ULOOP_WRITE;
 184
 185                 if (events[n].flags & EV_EOF)
 186                         u->eof = true;
 187                 else if (!ev)
 188                         cur->fd = NULL;
 189
 190                 cur->events = ev;
 191                 if (u->flags & ULOOP_EDGE_DEFER) {
 192                         u->flags &= ~ULOOP_EDGE_DEFER;
 193                         u->flags |= ULOOP_EDGE_TRIGGER;
 194                         register_kevent(u, u->flags);
 195                 }
 196         }
 197         return nfds;
 198 }
 199
 200 #endif
 201
 202 #ifdef USE_EPOLL
 203
 204 /**
 205  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
 206  */
 207 #ifndef EPOLLRDHUP
 208 #define EPOLLRDHUP 0x2000
 209 #endif
 210
 211 int uloop_init(void)
 212 {
 213         if (poll_fd >= 0)
 214                 return 0;
 215
 216         poll_fd = epoll_create(32);
 217         if (poll_fd < 0)
 218                 return -1;
 219
 220         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
 221         return 0;
 222 }
 223
 224 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 225 {
 226         struct epoll_event ev;
 227         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 228
 229         memset(&ev, 0, sizeof(struct epoll_event));
 230
 231         if (flags & ULOOP_READ)
 232                 ev.events |= EPOLLIN | EPOLLRDHUP;
 233
 234         if (flags & ULOOP_WRITE)
 235                 ev.events |= EPOLLOUT;
 236
 237         if (flags & ULOOP_EDGE_TRIGGER)
 238                 ev.events |= EPOLLET;
 239
 240         ev.data.fd = fd->fd;
 241         ev.data.ptr = fd;
 242         fd->flags = flags;
 243
 244         return epoll_ctl(poll_fd, op, fd->fd, &ev);
 245 }
 246
 247 static struct epoll_event events[ULOOP_MAX_EVENTS];
 248
 249 static int __uloop_fd_delete(struct uloop_fd *sock)
 250 {
 251         sock->flags = 0;
 252         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
 253 }
 254
 255 static int uloop_fetch_events(int timeout)
 256 {
 257         int n, nfds;
 258
 259         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
 260         for (n = 0; n < nfds; ++n) {
 261                 struct uloop_fd_event *cur = &cur_fds[n];
 262                 struct uloop_fd *u = events[n].data.ptr;
 263                 unsigned int ev = 0;
 264
 265                 cur->fd = u;
 266                 if (!u)
 267                         continue;
 268
 269                 if (events[n].events & (EPOLLERR|EPOLLHUP)) {
 270                         u->error = true;
 271                         if (!(u->flags & ULOOP_ERROR_CB))
 272                                 uloop_fd_delete(u);
 273                 }
 274
 275                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 276                         cur->fd = NULL;
 277                         continue;
 278                 }
 279
 280                 if(events[n].events & EPOLLRDHUP)
 281                         u->eof = true;
 282
 283                 if(events[n].events & EPOLLIN)
 284                         ev |= ULOOP_READ;
 285
 286                 if(events[n].events & EPOLLOUT)
 287                         ev |= ULOOP_WRITE;
 288
 289                 cur->events = ev;
 290         }
 291
 292         return nfds;
 293 }
 294
 295 #endif
 296
 297 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 298 {
 299         struct uloop_fd_stack *cur;
 300
 301         /*
 302          * Do not buffer events for level-triggered fds, they will keep firing.
 303          * Caller needs to take care of recursion issues.
 304          */
 305         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 306                 return false;
 307
 308         for (cur = fd_stack; cur; cur = cur->next) {
 309                 if (cur->fd != fd)
 310                         continue;
 311
 312                 if (events < 0)
 313                         cur->fd = NULL;
 314                 else
 315                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 316
 317                 return true;
 318         }
 319
 320         return false;
 321 }
 322
 323 static void uloop_run_events(int timeout)
 324 {
 325         struct uloop_fd_event *cur;
 326         struct uloop_fd *fd;
 327
 328         if (!cur_nfds) {
 329                 cur_fd = 0;
 330                 cur_nfds = uloop_fetch_events(timeout);
 331                 if (cur_nfds < 0)
 332                         cur_nfds = 0;
 333         }
 334
 335         while (cur_nfds > 0) {
 336                 struct uloop_fd_stack stack_cur;
 337                 unsigned int events;
 338
 339                 cur = &cur_fds[cur_fd++];
 340                 cur_nfds--;
 341
 342                 fd = cur->fd;
 343                 events = cur->events;
 344                 if (!fd)
 345                         continue;
 346
 347                 if (!fd->cb)
 348                         continue;
 349
 350                 if (uloop_fd_stack_event(fd, cur->events))
 351                         continue;
 352
 353                 stack_cur.next = fd_stack;
 354                 stack_cur.fd = fd;
 355                 fd_stack = &stack_cur;
 356                 do {
 357                         stack_cur.events = 0;
 358                         fd->cb(fd, events);
 359                         events = stack_cur.events & ULOOP_EVENT_MASK;
 360                 } while (stack_cur.fd && events);
 361                 fd_stack = stack_cur.next;
 362
 363                 return;
 364         }
 365 }
 366
 367 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 368 {
 369         unsigned int fl;
 370         int ret;
 371
 372         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 373                 return uloop_fd_delete(sock);
 374
 375         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 376                 fl = fcntl(sock->fd, F_GETFL, 0);
 377                 fl |= O_NONBLOCK;
 378                 fcntl(sock->fd, F_SETFL, fl);
 379         }
 380
 381         ret = register_poll(sock, flags);
 382         if (ret < 0)
 383                 goto out;
 384
 385         sock->registered = true;
 386         sock->eof = false;
 387         sock->error = false;
 388
 389 out:
 390         return ret;
 391 }
 392
 393 int uloop_fd_delete(struct uloop_fd *fd)
 394 {
 395         int i;
 396
 397         for (i = 0; i < cur_nfds; i++) {
 398                 if (cur_fds[cur_fd + i].fd != fd)
 399                         continue;
 400
 401                 cur_fds[cur_fd + i].fd = NULL;
 402         }
 403
 404         if (!fd->registered)
 405                 return 0;
 406
 407         fd->registered = false;
 408         uloop_fd_stack_event(fd, -1);
 409         return __uloop_fd_delete(fd);
 410 }
 411
 412 static int tv_diff(struct timeval *t1, struct timeval *t2)
 413 {
 414         return
 415                 (t1->tv_sec - t2->tv_sec) * 1000 +
 416                 (t1->tv_usec - t2->tv_usec) / 1000;
 417 }
 418
 419 int uloop_timeout_add(struct uloop_timeout *timeout)
 420 {
 421         struct uloop_timeout *tmp;
 422         struct list_head *h = &timeouts;
 423
 424         if (timeout->pending)
 425                 return -1;
 426
 427         list_for_each_entry(tmp, &timeouts, list) {
 428                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 429                         h = &tmp->list;
 430                         break;
 431                 }
 432         }
 433
 434         list_add_tail(&timeout->list, h);
 435         timeout->pending = true;
 436
 437         return 0;
 438 }
 439
 440 static void uloop_gettime(struct timeval *tv)
 441 {
 442         struct timespec ts;
 443
 444         clock_gettime(CLOCK_MONOTONIC, &ts);
 445         tv->tv_sec = ts.tv_sec;
 446         tv->tv_usec = ts.tv_nsec / 1000;
 447 }
 448
 449 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 450 {
 451         struct timeval *time = &timeout->time;
 452
 453         if (timeout->pending)
 454                 uloop_timeout_cancel(timeout);
 455
 456         uloop_gettime(time);
 457
 458         time->tv_sec += msecs / 1000;
 459         time->tv_usec += (msecs % 1000) * 1000;
 460
 461         if (time->tv_usec > 1000000) {
 462                 time->tv_sec++;
 463                 time->tv_usec -= 1000000;
 464         }
 465
 466         return uloop_timeout_add(timeout);
 467 }
 468
 469 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 470 {
 471         if (!timeout->pending)
 472                 return -1;
 473
 474         list_del(&timeout->list);
 475         timeout->pending = false;
 476
 477         return 0;
 478 }
 479
 480 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 481 {
 482         struct timeval now;
 483
 484         if (!timeout->pending)
 485                 return -1;
 486
 487         uloop_gettime(&now);
 488
 489         return tv_diff(&timeout->time, &now);
 490 }
 491
 492 int uloop_process_add(struct uloop_process *p)
 493 {
 494         struct uloop_process *tmp;
 495         struct list_head *h = &processes;
 496
 497         if (p->pending)
 498                 return -1;
 499
 500         list_for_each_entry(tmp, &processes, list) {
 501                 if (tmp->pid > p->pid) {
 502                         h = &tmp->list;
 503                         break;
 504                 }
 505         }
 506
 507         list_add_tail(&p->list, h);
 508         p->pending = true;
 509
 510         return 0;
 511 }
 512
 513 int uloop_process_delete(struct uloop_process *p)
 514 {
 515         if (!p->pending)
 516                 return -1;
 517
 518         list_del(&p->list);
 519         p->pending = false;
 520
 521         return 0;
 522 }
 523
 524 static void uloop_handle_processes(void)
 525 {
 526         struct uloop_process *p, *tmp;
 527         pid_t pid;
 528         int ret;
 529
 530         do_sigchld = false;
 531
 532         while (1) {
 533                 pid = waitpid(-1, &ret, WNOHANG);
 534                 if (pid <= 0)
 535                         return;
 536
 537                 list_for_each_entry_safe(p, tmp, &processes, list) {
 538                         if (p->pid < pid)
 539                                 continue;
 540
 541                         if (p->pid > pid)
 542                                 break;
 543
 544                         uloop_process_delete(p);
 545                         p->cb(p, ret);
 546                 }
 547         }
 548
 549 }
 550
 551 static void uloop_handle_sigint(int signo)
 552 {
 553         uloop_cancelled = true;
 554 }
 555
 556 static void uloop_sigchld(int signo)
 557 {
 558         do_sigchld = true;
 559 }
 560
 561 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 562 {
 563         struct sigaction s;
 564         struct sigaction *act;
 565
 566         act = NULL;
 567         sigaction(signum, NULL, &s);
 568
 569         if (add) {
 570                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 571                         memcpy(old, &s, sizeof(struct sigaction));
 572                         s.sa_handler = handler;
 573                         s.sa_flags = 0;
 574                         act = &s;
 575                 }
 576         }
 577         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 578                         act = old;
 579         }
 580
 581         if (act != NULL)
 582                 sigaction(signum, act, NULL);
 583 }
 584
 585 static void uloop_ignore_signal(int signum, bool ignore)
 586 {
 587         struct sigaction s;
 588         void *new_handler = NULL;
 589
 590         sigaction(signum, NULL, &s);
 591
 592         if (ignore) {
 593                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 594                         new_handler = SIG_IGN;
 595         } else {
 596                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 597                         new_handler = SIG_DFL;
 598         }
 599
 600         if (new_handler) {
 601                 s.sa_handler = new_handler;
 602                 s.sa_flags = 0;
 603                 sigaction(signum, &s, NULL);
 604         }
 605 }
 606
 607 static void uloop_setup_signals(bool add)
 608 {
 609         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 610
 611         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 612         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 613         uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 614
 615         uloop_ignore_signal(SIGPIPE, add);
 616 }
 617
 618 static int uloop_get_next_timeout(struct timeval *tv)
 619 {
 620         struct uloop_timeout *timeout;
 621         int diff;
 622
 623         if (list_empty(&timeouts))
 624                 return -1;
 625
 626         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 627         diff = tv_diff(&timeout->time, tv);
 628         if (diff < 0)
 629                 return 0;
 630
 631         return diff;
 632 }
 633
 634 static void uloop_process_timeouts(struct timeval *tv)
 635 {
 636         struct uloop_timeout *t;
 637
 638         while (!list_empty(&timeouts)) {
 639                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 640
 641                 if (tv_diff(&t->time, tv) > 0)
 642                         break;
 643
 644                 uloop_timeout_cancel(t);
 645                 if (t->cb)
 646                         t->cb(t);
 647         }
 648 }
 649
 650 static void uloop_clear_timeouts(void)
 651 {
 652         struct uloop_timeout *t, *tmp;
 653
 654         list_for_each_entry_safe(t, tmp, &timeouts, list)
 655                 uloop_timeout_cancel(t);
 656 }
 657
 658 static void uloop_clear_processes(void)
 659 {
 660         struct uloop_process *p, *tmp;
 661
 662         list_for_each_entry_safe(p, tmp, &processes, list)
 663                 uloop_process_delete(p);
 664 }
 665
 666 void uloop_run(void)
 667 {
 668         static int recursive_calls = 0;
 669         struct timeval tv;
 670
 671         /*
 672          * Handlers are only updated for the first call to uloop_run() (and restored
 673          * when this call is done).
 674          */
 675         if (!recursive_calls++)
 676                 uloop_setup_signals(true);
 677
 678         uloop_cancelled = false;
 679         while(!uloop_cancelled)
 680         {
 681                 uloop_gettime(&tv);
 682                 uloop_process_timeouts(&tv);
 683
 684                 if (do_sigchld)
 685                         uloop_handle_processes();
 686
 687                 if (uloop_cancelled)
 688                         break;
 689
 690                 uloop_gettime(&tv);
 691                 uloop_run_events(uloop_get_next_timeout(&tv));
 692         }
 693
 694         if (!--recursive_calls)
 695                 uloop_setup_signals(false);
 696 }
 697
 698 void uloop_done(void)
 699 {
 700         if (poll_fd < 0)
 701                 return;
 702
 703         close(poll_fd);
 704         poll_fd = -1;
 705
 706         uloop_clear_timeouts();
 707         uloop_clear_processes();
 708 }