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 bool uloop_handle_sigchld = true;
  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 #ifdef USE_KQUEUE
  68
  69 int uloop_init(void)
  70 {
  71         struct timespec timeout = { 0, 0 };
  72         struct kevent ev = {};
  73
  74         if (poll_fd >= 0)
  75                 return 0;
  76
  77         poll_fd = kqueue();
  78         if (poll_fd < 0)
  79                 return -1;
  80
  81         EV_SET(&ev, SIGCHLD, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
  82         kevent(poll_fd, &ev, 1, NULL, 0, &timeout);
  83
  84         return 0;
  85 }
  86
  87
  88 static uint16_t get_flags(unsigned int flags, unsigned int mask)
  89 {
  90         uint16_t kflags = 0;
  91
  92         if (!(flags & mask))
  93                 return EV_DELETE;
  94
  95         kflags = EV_ADD;
  96         if (flags & ULOOP_EDGE_TRIGGER)
  97                 kflags |= EV_CLEAR;
  98
  99         return kflags;
 100 }
 101
 102 static struct kevent events[ULOOP_MAX_EVENTS];
 103
 104 static int register_kevent(struct uloop_fd *fd, unsigned int flags)
 105 {
 106         struct timespec timeout = { 0, 0 };
 107         struct kevent ev[2];
 108         int nev = 0;
 109         unsigned int fl = 0;
 110         unsigned int changed;
 111         uint16_t kflags;
 112
 113         if (flags & ULOOP_EDGE_DEFER)
 114                 flags &= ~ULOOP_EDGE_TRIGGER;
 115
 116         changed = flags ^ fd->flags;
 117         if (changed & ULOOP_EDGE_TRIGGER)
 118                 changed |= flags;
 119
 120         if (changed & ULOOP_READ) {
 121                 kflags = get_flags(flags, ULOOP_READ);
 122                 EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
 123         }
 124
 125         if (changed & ULOOP_WRITE) {
 126                 kflags = get_flags(flags, ULOOP_WRITE);
 127                 EV_SET(&ev[nev++], fd->fd, EVFILT_WRITE, kflags, 0, 0, fd);
 128         }
 129
 130         if (!flags)
 131                 fl |= EV_DELETE;
 132
 133         fd->flags = flags;
 134         if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
 135                 return -1;
 136
 137         return 0;
 138 }
 139
 140 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 141 {
 142         if (flags & ULOOP_EDGE_TRIGGER)
 143                 flags |= ULOOP_EDGE_DEFER;
 144         else
 145                 flags &= ~ULOOP_EDGE_DEFER;
 146
 147         return register_kevent(fd, flags);
 148 }
 149
 150 static int __uloop_fd_delete(struct uloop_fd *fd)
 151 {
 152         return register_poll(fd, 0);
 153 }
 154
 155 static int uloop_fetch_events(int timeout)
 156 {
 157         struct timespec ts;
 158         int nfds, n;
 159
 160         if (timeout >= 0) {
 161                 ts.tv_sec = timeout / 1000;
 162                 ts.tv_nsec = (timeout % 1000) * 1000000;
 163         }
 164
 165         nfds = kevent(poll_fd, NULL, 0, events, ARRAY_SIZE(events), timeout >= 0 ? &ts : NULL);
 166         for (n = 0; n < nfds; n++) {
 167                 struct uloop_fd_event *cur = &cur_fds[n];
 168                 struct uloop_fd *u = events[n].udata;
 169                 unsigned int ev = 0;
 170
 171                 cur->fd = u;
 172                 if (!u)
 173                         continue;
 174
 175                 if (events[n].flags & EV_ERROR) {
 176                         u->error = true;
 177                         if (!(u->flags & ULOOP_ERROR_CB))
 178                                 uloop_fd_delete(u);
 179                 }
 180
 181                 if(events[n].filter == EVFILT_READ)
 182                         ev |= ULOOP_READ;
 183                 else if (events[n].filter == EVFILT_WRITE)
 184                         ev |= ULOOP_WRITE;
 185
 186                 if (events[n].flags & EV_EOF)
 187                         u->eof = true;
 188                 else if (!ev)
 189                         cur->fd = NULL;
 190
 191                 cur->events = ev;
 192                 if (u->flags & ULOOP_EDGE_DEFER) {
 193                         u->flags &= ~ULOOP_EDGE_DEFER;
 194                         u->flags |= ULOOP_EDGE_TRIGGER;
 195                         register_kevent(u, u->flags);
 196                 }
 197         }
 198         return nfds;
 199 }
 200
 201 #endif
 202
 203 #ifdef USE_EPOLL
 204
 205 /**
 206  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
 207  */
 208 #ifndef EPOLLRDHUP
 209 #define EPOLLRDHUP 0x2000
 210 #endif
 211
 212 int uloop_init(void)
 213 {
 214         if (poll_fd >= 0)
 215                 return 0;
 216
 217         poll_fd = epoll_create(32);
 218         if (poll_fd < 0)
 219                 return -1;
 220
 221         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
 222         return 0;
 223 }
 224
 225 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 226 {
 227         struct epoll_event ev;
 228         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 229
 230         memset(&ev, 0, sizeof(struct epoll_event));
 231
 232         if (flags & ULOOP_READ)
 233                 ev.events |= EPOLLIN | EPOLLRDHUP;
 234
 235         if (flags & ULOOP_WRITE)
 236                 ev.events |= EPOLLOUT;
 237
 238         if (flags & ULOOP_EDGE_TRIGGER)
 239                 ev.events |= EPOLLET;
 240
 241         ev.data.fd = fd->fd;
 242         ev.data.ptr = fd;
 243         fd->flags = flags;
 244
 245         return epoll_ctl(poll_fd, op, fd->fd, &ev);
 246 }
 247
 248 static struct epoll_event events[ULOOP_MAX_EVENTS];
 249
 250 static int __uloop_fd_delete(struct uloop_fd *sock)
 251 {
 252         sock->flags = 0;
 253         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
 254 }
 255
 256 static int uloop_fetch_events(int timeout)
 257 {
 258         int n, nfds;
 259
 260         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
 261         for (n = 0; n < nfds; ++n) {
 262                 struct uloop_fd_event *cur = &cur_fds[n];
 263                 struct uloop_fd *u = events[n].data.ptr;
 264                 unsigned int ev = 0;
 265
 266                 cur->fd = u;
 267                 if (!u)
 268                         continue;
 269
 270                 if (events[n].events & (EPOLLERR|EPOLLHUP)) {
 271                         u->error = true;
 272                         if (!(u->flags & ULOOP_ERROR_CB))
 273                                 uloop_fd_delete(u);
 274                 }
 275
 276                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 277                         cur->fd = NULL;
 278                         continue;
 279                 }
 280
 281                 if(events[n].events & EPOLLRDHUP)
 282                         u->eof = true;
 283
 284                 if(events[n].events & EPOLLIN)
 285                         ev |= ULOOP_READ;
 286
 287                 if(events[n].events & EPOLLOUT)
 288                         ev |= ULOOP_WRITE;
 289
 290                 cur->events = ev;
 291         }
 292
 293         return nfds;
 294 }
 295
 296 #endif
 297
 298 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 299 {
 300         struct uloop_fd_stack *cur;
 301
 302         /*
 303          * Do not buffer events for level-triggered fds, they will keep firing.
 304          * Caller needs to take care of recursion issues.
 305          */
 306         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 307                 return false;
 308
 309         for (cur = fd_stack; cur; cur = cur->next) {
 310                 if (cur->fd != fd)
 311                         continue;
 312
 313                 if (events < 0)
 314                         cur->fd = NULL;
 315                 else
 316                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 317
 318                 return true;
 319         }
 320
 321         return false;
 322 }
 323
 324 static void uloop_run_events(int timeout)
 325 {
 326         struct uloop_fd_event *cur;
 327         struct uloop_fd *fd;
 328
 329         if (!cur_nfds) {
 330                 cur_fd = 0;
 331                 cur_nfds = uloop_fetch_events(timeout);
 332                 if (cur_nfds < 0)
 333                         cur_nfds = 0;
 334         }
 335
 336         while (cur_nfds > 0) {
 337                 struct uloop_fd_stack stack_cur;
 338                 unsigned int events;
 339
 340                 cur = &cur_fds[cur_fd++];
 341                 cur_nfds--;
 342
 343                 fd = cur->fd;
 344                 events = cur->events;
 345                 if (!fd)
 346                         continue;
 347
 348                 if (!fd->cb)
 349                         continue;
 350
 351                 if (uloop_fd_stack_event(fd, cur->events))
 352                         continue;
 353
 354                 stack_cur.next = fd_stack;
 355                 stack_cur.fd = fd;
 356                 fd_stack = &stack_cur;
 357                 do {
 358                         stack_cur.events = 0;
 359                         fd->cb(fd, events);
 360                         events = stack_cur.events & ULOOP_EVENT_MASK;
 361                 } while (stack_cur.fd && events);
 362                 fd_stack = stack_cur.next;
 363
 364                 return;
 365         }
 366 }
 367
 368 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 369 {
 370         unsigned int fl;
 371         int ret;
 372
 373         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 374                 return uloop_fd_delete(sock);
 375
 376         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 377                 fl = fcntl(sock->fd, F_GETFL, 0);
 378                 fl |= O_NONBLOCK;
 379                 fcntl(sock->fd, F_SETFL, fl);
 380         }
 381
 382         ret = register_poll(sock, flags);
 383         if (ret < 0)
 384                 goto out;
 385
 386         sock->registered = true;
 387         sock->eof = 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(&timeout->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_setup_signals(bool add)
 562 {
 563         static struct sigaction old_sigint, old_sigchld;
 564         struct sigaction s;
 565
 566         memset(&s, 0, sizeof(struct sigaction));
 567
 568         if (add) {
 569                 s.sa_handler = uloop_handle_sigint;
 570                 s.sa_flags = 0;
 571         } else {
 572                 s = old_sigint;
 573         }
 574
 575         sigaction(SIGINT, &s, &old_sigint);
 576
 577         if (!uloop_handle_sigchld)
 578                 return;
 579
 580         if (add)
 581                 s.sa_handler = uloop_sigchld;
 582         else
 583                 s = old_sigchld;
 584
 585         sigaction(SIGCHLD, &s, &old_sigchld);
 586 }
 587
 588 static int uloop_get_next_timeout(struct timeval *tv)
 589 {
 590         struct uloop_timeout *timeout;
 591         int diff;
 592
 593         if (list_empty(&timeouts))
 594                 return -1;
 595
 596         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 597         diff = tv_diff(&timeout->time, tv);
 598         if (diff < 0)
 599                 return 0;
 600
 601         return diff;
 602 }
 603
 604 static void uloop_process_timeouts(struct timeval *tv)
 605 {
 606         struct uloop_timeout *t;
 607
 608         while (!list_empty(&timeouts)) {
 609                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 610
 611                 if (tv_diff(&t->time, tv) > 0)
 612                         break;
 613
 614                 uloop_timeout_cancel(t);
 615                 if (t->cb)
 616                         t->cb(t);
 617         }
 618 }
 619
 620 static void uloop_clear_timeouts(void)
 621 {
 622         struct uloop_timeout *t, *tmp;
 623
 624         list_for_each_entry_safe(t, tmp, &timeouts, list)
 625                 uloop_timeout_cancel(t);
 626 }
 627
 628 static void uloop_clear_processes(void)
 629 {
 630         struct uloop_process *p, *tmp;
 631
 632         list_for_each_entry_safe(p, tmp, &processes, list)
 633                 uloop_process_delete(p);
 634 }
 635
 636 void uloop_run(void)
 637 {
 638         static int recursive_calls = 0;
 639         struct timeval tv;
 640
 641         /*
 642          * Handlers are only updated for the first call to uloop_run() (and restored
 643          * when this call is done).
 644          */
 645         if (!recursive_calls++)
 646                 uloop_setup_signals(true);
 647
 648         while(!uloop_cancelled)
 649         {
 650                 uloop_gettime(&tv);
 651                 uloop_process_timeouts(&tv);
 652                 if (uloop_cancelled)
 653                         break;
 654
 655                 if (do_sigchld)
 656                         uloop_handle_processes();
 657                 uloop_gettime(&tv);
 658                 uloop_run_events(uloop_get_next_timeout(&tv));
 659         }
 660
 661         if (!--recursive_calls)
 662                 uloop_setup_signals(false);
 663 }
 664
 665 void uloop_done(void)
 666 {
 667         if (poll_fd < 0)
 668                 return;
 669
 670         close(poll_fd);
 671         poll_fd = -1;
 672
 673         uloop_clear_timeouts();
 674         uloop_clear_processes();
 675 }