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         sock->error = false;
 389
 390 out:
 391         return ret;
 392 }
 393
 394 int uloop_fd_delete(struct uloop_fd *fd)
 395 {
 396         int i;
 397
 398         for (i = 0; i < cur_nfds; i++) {
 399                 if (cur_fds[cur_fd + i].fd != fd)
 400                         continue;
 401
 402                 cur_fds[cur_fd + i].fd = NULL;
 403         }
 404
 405         if (!fd->registered)
 406                 return 0;
 407
 408         fd->registered = false;
 409         uloop_fd_stack_event(fd, -1);
 410         return __uloop_fd_delete(fd);
 411 }
 412
 413 static int tv_diff(struct timeval *t1, struct timeval *t2)
 414 {
 415         return
 416                 (t1->tv_sec - t2->tv_sec) * 1000 +
 417                 (t1->tv_usec - t2->tv_usec) / 1000;
 418 }
 419
 420 int uloop_timeout_add(struct uloop_timeout *timeout)
 421 {
 422         struct uloop_timeout *tmp;
 423         struct list_head *h = &timeouts;
 424
 425         if (timeout->pending)
 426                 return -1;
 427
 428         list_for_each_entry(tmp, &timeouts, list) {
 429                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 430                         h = &tmp->list;
 431                         break;
 432                 }
 433         }
 434
 435         list_add_tail(&timeout->list, h);
 436         timeout->pending = true;
 437
 438         return 0;
 439 }
 440
 441 static void uloop_gettime(struct timeval *tv)
 442 {
 443         struct timespec ts;
 444
 445         clock_gettime(CLOCK_MONOTONIC, &ts);
 446         tv->tv_sec = ts.tv_sec;
 447         tv->tv_usec = ts.tv_nsec / 1000;
 448 }
 449
 450 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 451 {
 452         struct timeval *time = &timeout->time;
 453
 454         if (timeout->pending)
 455                 uloop_timeout_cancel(timeout);
 456
 457         uloop_gettime(&timeout->time);
 458
 459         time->tv_sec += msecs / 1000;
 460         time->tv_usec += (msecs % 1000) * 1000;
 461
 462         if (time->tv_usec > 1000000) {
 463                 time->tv_sec++;
 464                 time->tv_usec %= 1000000;
 465         }
 466
 467         return uloop_timeout_add(timeout);
 468 }
 469
 470 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 471 {
 472         if (!timeout->pending)
 473                 return -1;
 474
 475         list_del(&timeout->list);
 476         timeout->pending = false;
 477
 478         return 0;
 479 }
 480
 481 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 482 {
 483         struct timeval now;
 484
 485         if (!timeout->pending)
 486                 return -1;
 487
 488         uloop_gettime(&now);
 489
 490         return tv_diff(&timeout->time, &now);
 491 }
 492
 493 int uloop_process_add(struct uloop_process *p)
 494 {
 495         struct uloop_process *tmp;
 496         struct list_head *h = &processes;
 497
 498         if (p->pending)
 499                 return -1;
 500
 501         list_for_each_entry(tmp, &processes, list) {
 502                 if (tmp->pid > p->pid) {
 503                         h = &tmp->list;
 504                         break;
 505                 }
 506         }
 507
 508         list_add_tail(&p->list, h);
 509         p->pending = true;
 510
 511         return 0;
 512 }
 513
 514 int uloop_process_delete(struct uloop_process *p)
 515 {
 516         if (!p->pending)
 517                 return -1;
 518
 519         list_del(&p->list);
 520         p->pending = false;
 521
 522         return 0;
 523 }
 524
 525 static void uloop_handle_processes(void)
 526 {
 527         struct uloop_process *p, *tmp;
 528         pid_t pid;
 529         int ret;
 530
 531         do_sigchld = false;
 532
 533         while (1) {
 534                 pid = waitpid(-1, &ret, WNOHANG);
 535                 if (pid <= 0)
 536                         return;
 537
 538                 list_for_each_entry_safe(p, tmp, &processes, list) {
 539                         if (p->pid < pid)
 540                                 continue;
 541
 542                         if (p->pid > pid)
 543                                 break;
 544
 545                         uloop_process_delete(p);
 546                         p->cb(p, ret);
 547                 }
 548         }
 549
 550 }
 551
 552 static void uloop_handle_sigint(int signo)
 553 {
 554         uloop_cancelled = true;
 555 }
 556
 557 static void uloop_sigchld(int signo)
 558 {
 559         do_sigchld = true;
 560 }
 561
 562 static void uloop_setup_signals(bool add)
 563 {
 564         static struct sigaction old_sigint, old_sigchld;
 565         struct sigaction s;
 566
 567         memset(&s, 0, sizeof(struct sigaction));
 568
 569         if (add) {
 570                 s.sa_handler = uloop_handle_sigint;
 571                 s.sa_flags = 0;
 572         } else {
 573                 s = old_sigint;
 574         }
 575
 576         sigaction(SIGINT, &s, &old_sigint);
 577
 578         if (!uloop_handle_sigchld)
 579                 return;
 580
 581         if (add)
 582                 s.sa_handler = uloop_sigchld;
 583         else
 584                 s = old_sigchld;
 585
 586         sigaction(SIGCHLD, &s, &old_sigchld);
 587 }
 588
 589 static int uloop_get_next_timeout(struct timeval *tv)
 590 {
 591         struct uloop_timeout *timeout;
 592         int diff;
 593
 594         if (list_empty(&timeouts))
 595                 return -1;
 596
 597         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 598         diff = tv_diff(&timeout->time, tv);
 599         if (diff < 0)
 600                 return 0;
 601
 602         return diff;
 603 }
 604
 605 static void uloop_process_timeouts(struct timeval *tv)
 606 {
 607         struct uloop_timeout *t;
 608
 609         while (!list_empty(&timeouts)) {
 610                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 611
 612                 if (tv_diff(&t->time, tv) > 0)
 613                         break;
 614
 615                 uloop_timeout_cancel(t);
 616                 if (t->cb)
 617                         t->cb(t);
 618         }
 619 }
 620
 621 static void uloop_clear_timeouts(void)
 622 {
 623         struct uloop_timeout *t, *tmp;
 624
 625         list_for_each_entry_safe(t, tmp, &timeouts, list)
 626                 uloop_timeout_cancel(t);
 627 }
 628
 629 static void uloop_clear_processes(void)
 630 {
 631         struct uloop_process *p, *tmp;
 632
 633         list_for_each_entry_safe(p, tmp, &processes, list)
 634                 uloop_process_delete(p);
 635 }
 636
 637 void uloop_run(void)
 638 {
 639         static int recursive_calls = 0;
 640         struct timeval tv;
 641
 642         /*
 643          * Handlers are only updated for the first call to uloop_run() (and restored
 644          * when this call is done).
 645          */
 646         if (!recursive_calls++)
 647                 uloop_setup_signals(true);
 648
 649         uloop_cancelled = false;
 650         while(!uloop_cancelled)
 651         {
 652                 uloop_gettime(&tv);
 653                 uloop_process_timeouts(&tv);
 654                 if (uloop_cancelled)
 655                         break;
 656
 657                 if (do_sigchld)
 658                         uloop_handle_processes();
 659                 uloop_gettime(&tv);
 660                 uloop_run_events(uloop_get_next_timeout(&tv));
 661         }
 662
 663         if (!--recursive_calls)
 664                 uloop_setup_signals(false);
 665 }
 666
 667 void uloop_done(void)
 668 {
 669         if (poll_fd < 0)
 670                 return;
 671
 672         close(poll_fd);
 673         poll_fd = -1;
 674
 675         uloop_clear_timeouts();
 676         uloop_clear_processes();
 677 }