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                         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                         uloop_fd_delete(u);
 272                 }
 273
 274                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 275                         cur->fd = NULL;
 276                         continue;
 277                 }
 278
 279                 if(events[n].events & EPOLLRDHUP)
 280                         u->eof = true;
 281
 282                 if(events[n].events & EPOLLIN)
 283                         ev |= ULOOP_READ;
 284
 285                 if(events[n].events & EPOLLOUT)
 286                         ev |= ULOOP_WRITE;
 287
 288                 cur->events = ev;
 289         }
 290
 291         return nfds;
 292 }
 293
 294 #endif
 295
 296 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 297 {
 298         struct uloop_fd_stack *cur;
 299
 300         /*
 301          * Do not buffer events for level-triggered fds, they will keep firing.
 302          * Caller needs to take care of recursion issues.
 303          */
 304         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 305                 return false;
 306
 307         for (cur = fd_stack; cur; cur = cur->next) {
 308                 if (cur->fd != fd)
 309                         continue;
 310
 311                 if (events < 0)
 312                         cur->fd = NULL;
 313                 else
 314                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 315
 316                 return true;
 317         }
 318
 319         return false;
 320 }
 321
 322 static void uloop_run_events(int timeout)
 323 {
 324         struct uloop_fd_event *cur;
 325         struct uloop_fd *fd;
 326
 327         if (!cur_nfds) {
 328                 cur_fd = 0;
 329                 cur_nfds = uloop_fetch_events(timeout);
 330                 if (cur_nfds < 0)
 331                         cur_nfds = 0;
 332         }
 333
 334         while (cur_nfds > 0) {
 335                 struct uloop_fd_stack stack_cur;
 336                 unsigned int events;
 337
 338                 cur = &cur_fds[cur_fd++];
 339                 cur_nfds--;
 340
 341                 fd = cur->fd;
 342                 events = cur->events;
 343                 if (!fd)
 344                         continue;
 345
 346                 if (!fd->cb)
 347                         continue;
 348
 349                 if (uloop_fd_stack_event(fd, cur->events))
 350                         continue;
 351
 352                 stack_cur.next = fd_stack;
 353                 stack_cur.fd = fd;
 354                 fd_stack = &stack_cur;
 355                 do {
 356                         stack_cur.events = 0;
 357                         fd->cb(fd, events);
 358                         events = stack_cur.events & ULOOP_EVENT_MASK;
 359                 } while (stack_cur.fd && events);
 360                 fd_stack = stack_cur.next;
 361
 362                 return;
 363         }
 364 }
 365
 366 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 367 {
 368         unsigned int fl;
 369         int ret;
 370
 371         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 372                 return uloop_fd_delete(sock);
 373
 374         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 375                 fl = fcntl(sock->fd, F_GETFL, 0);
 376                 fl |= O_NONBLOCK;
 377                 fcntl(sock->fd, F_SETFL, fl);
 378         }
 379
 380         ret = register_poll(sock, flags);
 381         if (ret < 0)
 382                 goto out;
 383
 384         sock->registered = true;
 385         sock->eof = false;
 386
 387 out:
 388         return ret;
 389 }
 390
 391 int uloop_fd_delete(struct uloop_fd *fd)
 392 {
 393         int i;
 394
 395         for (i = 0; i < cur_nfds; i++) {
 396                 if (cur_fds[cur_fd + i].fd != fd)
 397                         continue;
 398
 399                 cur_fds[cur_fd + i].fd = NULL;
 400         }
 401
 402         if (!fd->registered)
 403                 return 0;
 404
 405         fd->registered = false;
 406         uloop_fd_stack_event(fd, -1);
 407         return __uloop_fd_delete(fd);
 408 }
 409
 410 static int tv_diff(struct timeval *t1, struct timeval *t2)
 411 {
 412         return
 413                 (t1->tv_sec - t2->tv_sec) * 1000 +
 414                 (t1->tv_usec - t2->tv_usec) / 1000;
 415 }
 416
 417 int uloop_timeout_add(struct uloop_timeout *timeout)
 418 {
 419         struct uloop_timeout *tmp;
 420         struct list_head *h = &timeouts;
 421
 422         if (timeout->pending)
 423                 return -1;
 424
 425         list_for_each_entry(tmp, &timeouts, list) {
 426                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 427                         h = &tmp->list;
 428                         break;
 429                 }
 430         }
 431
 432         list_add_tail(&timeout->list, h);
 433         timeout->pending = true;
 434
 435         return 0;
 436 }
 437
 438 static void uloop_gettime(struct timeval *tv)
 439 {
 440         struct timespec ts;
 441
 442         clock_gettime(CLOCK_MONOTONIC, &ts);
 443         tv->tv_sec = ts.tv_sec;
 444         tv->tv_usec = ts.tv_nsec / 1000;
 445 }
 446
 447 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 448 {
 449         struct timeval *time = &timeout->time;
 450
 451         if (timeout->pending)
 452                 uloop_timeout_cancel(timeout);
 453
 454         uloop_gettime(&timeout->time);
 455
 456         time->tv_sec += msecs / 1000;
 457         time->tv_usec += (msecs % 1000) * 1000;
 458
 459         if (time->tv_usec > 1000000) {
 460                 time->tv_sec++;
 461                 time->tv_usec %= 1000000;
 462         }
 463
 464         return uloop_timeout_add(timeout);
 465 }
 466
 467 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 468 {
 469         if (!timeout->pending)
 470                 return -1;
 471
 472         list_del(&timeout->list);
 473         timeout->pending = false;
 474
 475         return 0;
 476 }
 477
 478 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 479 {
 480         struct timeval now;
 481
 482         if (!timeout->pending)
 483                 return -1;
 484
 485         uloop_gettime(&now);
 486
 487         return tv_diff(&timeout->time, &now);
 488 }
 489
 490 int uloop_process_add(struct uloop_process *p)
 491 {
 492         struct uloop_process *tmp;
 493         struct list_head *h = &processes;
 494
 495         if (p->pending)
 496                 return -1;
 497
 498         list_for_each_entry(tmp, &processes, list) {
 499                 if (tmp->pid > p->pid) {
 500                         h = &tmp->list;
 501                         break;
 502                 }
 503         }
 504
 505         list_add_tail(&p->list, h);
 506         p->pending = true;
 507
 508         return 0;
 509 }
 510
 511 int uloop_process_delete(struct uloop_process *p)
 512 {
 513         if (!p->pending)
 514                 return -1;
 515
 516         list_del(&p->list);
 517         p->pending = false;
 518
 519         return 0;
 520 }
 521
 522 static void uloop_handle_processes(void)
 523 {
 524         struct uloop_process *p, *tmp;
 525         pid_t pid;
 526         int ret;
 527
 528         do_sigchld = false;
 529
 530         while (1) {
 531                 pid = waitpid(-1, &ret, WNOHANG);
 532                 if (pid <= 0)
 533                         return;
 534
 535                 list_for_each_entry_safe(p, tmp, &processes, list) {
 536                         if (p->pid < pid)
 537                                 continue;
 538
 539                         if (p->pid > pid)
 540                                 break;
 541
 542                         uloop_process_delete(p);
 543                         p->cb(p, ret);
 544                 }
 545         }
 546
 547 }
 548
 549 static void uloop_handle_sigint(int signo)
 550 {
 551         uloop_cancelled = true;
 552 }
 553
 554 static void uloop_sigchld(int signo)
 555 {
 556         do_sigchld = true;
 557 }
 558
 559 static void uloop_setup_signals(void)
 560 {
 561         struct sigaction s;
 562
 563         memset(&s, 0, sizeof(struct sigaction));
 564         s.sa_handler = uloop_handle_sigint;
 565         s.sa_flags = 0;
 566         sigaction(SIGINT, &s, NULL);
 567
 568         if (uloop_handle_sigchld) {
 569                 s.sa_handler = uloop_sigchld;
 570                 sigaction(SIGCHLD, &s, NULL);
 571         }
 572 }
 573
 574 static int uloop_get_next_timeout(struct timeval *tv)
 575 {
 576         struct uloop_timeout *timeout;
 577         int diff;
 578
 579         if (list_empty(&timeouts))
 580                 return -1;
 581
 582         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 583         diff = tv_diff(&timeout->time, tv);
 584         if (diff < 0)
 585                 return 0;
 586
 587         return diff;
 588 }
 589
 590 static void uloop_process_timeouts(struct timeval *tv)
 591 {
 592         struct uloop_timeout *t;
 593
 594         while (!list_empty(&timeouts)) {
 595                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 596
 597                 if (tv_diff(&t->time, tv) > 0)
 598                         break;
 599
 600                 uloop_timeout_cancel(t);
 601                 if (t->cb)
 602                         t->cb(t);
 603         }
 604 }
 605
 606 static void uloop_clear_timeouts(void)
 607 {
 608         struct uloop_timeout *t, *tmp;
 609
 610         list_for_each_entry_safe(t, tmp, &timeouts, list)
 611                 uloop_timeout_cancel(t);
 612 }
 613
 614 static void uloop_clear_processes(void)
 615 {
 616         struct uloop_process *p, *tmp;
 617
 618         list_for_each_entry_safe(p, tmp, &processes, list)
 619                 uloop_process_delete(p);
 620 }
 621
 622 void uloop_run(void)
 623 {
 624         struct timeval tv;
 625
 626         uloop_setup_signals();
 627         while(!uloop_cancelled)
 628         {
 629                 uloop_gettime(&tv);
 630                 uloop_process_timeouts(&tv);
 631                 if (uloop_cancelled)
 632                         break;
 633
 634                 if (do_sigchld)
 635                         uloop_handle_processes();
 636                 uloop_gettime(&tv);
 637                 uloop_run_events(uloop_get_next_timeout(&tv));
 638         }
 639 }
 640
 641 void uloop_done(void)
 642 {
 643         if (poll_fd < 0)
 644                 return;
 645
 646         close(poll_fd);
 647         poll_fd = -1;
 648
 649         uloop_clear_timeouts();
 650         uloop_clear_processes();
 651 }