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 #define ULOOP_MAX_EVENTS 10
  47
  48 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
  49 static struct list_head processes = LIST_HEAD_INIT(processes);
  50
  51 static int poll_fd = -1;
  52 bool uloop_cancelled = false;
  53 bool uloop_handle_sigchld = true;
  54 static bool do_sigchld = false;
  55
  56 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  57 static int cur_fd, cur_nfds;
  58
  59 #ifdef USE_KQUEUE
  60
  61 int uloop_init(void)
  62 {
  63         struct timespec timeout = { 0, 0 };
  64         struct kevent ev = {};
  65
  66         if (poll_fd >= 0)
  67                 return 0;
  68
  69         poll_fd = kqueue();
  70         if (poll_fd < 0)
  71                 return -1;
  72
  73         EV_SET(&ev, SIGCHLD, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
  74         kevent(poll_fd, &ev, 1, NULL, 0, &timeout);
  75
  76         return 0;
  77 }
  78
  79
  80 static uint16_t get_flags(unsigned int flags, unsigned int mask)
  81 {
  82         uint16_t kflags = 0;
  83
  84         if (!(flags & mask))
  85                 return EV_DELETE;
  86
  87         kflags = EV_ADD;
  88         if (flags & ULOOP_EDGE_TRIGGER)
  89                 kflags |= EV_CLEAR;
  90
  91         return kflags;
  92 }
  93
  94 static struct kevent events[ULOOP_MAX_EVENTS];
  95
  96 static int register_kevent(struct uloop_fd *fd, unsigned int flags)
  97 {
  98         struct timespec timeout = { 0, 0 };
  99         struct kevent ev[2];
 100         int nev = 0;
 101         unsigned int fl = 0;
 102         unsigned int changed;
 103         uint16_t kflags;
 104
 105         if (flags & ULOOP_EDGE_DEFER)
 106                 flags &= ~ULOOP_EDGE_TRIGGER;
 107
 108         changed = flags ^ fd->flags;
 109         if (changed & ULOOP_EDGE_TRIGGER)
 110                 changed |= flags;
 111
 112         if (changed & ULOOP_READ) {
 113                 kflags = get_flags(flags, ULOOP_READ);
 114                 EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
 115         }
 116
 117         if (changed & ULOOP_WRITE) {
 118                 kflags = get_flags(flags, ULOOP_WRITE);
 119                 EV_SET(&ev[nev++], fd->fd, EVFILT_WRITE, kflags, 0, 0, fd);
 120         }
 121
 122         if (!flags)
 123                 fl |= EV_DELETE;
 124
 125         fd->flags = flags;
 126         if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
 127                 return -1;
 128
 129         return 0;
 130 }
 131
 132 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 133 {
 134         if (flags & ULOOP_EDGE_TRIGGER)
 135                 flags |= ULOOP_EDGE_DEFER;
 136         else
 137                 flags &= ~ULOOP_EDGE_DEFER;
 138
 139         return register_kevent(fd, flags);
 140 }
 141
 142 static int __uloop_fd_delete(struct uloop_fd *fd)
 143 {
 144         return register_poll(fd, 0);
 145 }
 146
 147 static int uloop_fetch_events(int timeout)
 148 {
 149         struct timespec ts;
 150         int nfds, n;
 151
 152         if (timeout >= 0) {
 153                 ts.tv_sec = timeout / 1000;
 154                 ts.tv_nsec = (timeout % 1000) * 1000000;
 155         }
 156
 157         nfds = kevent(poll_fd, NULL, 0, events, ARRAY_SIZE(events), timeout >= 0 ? &ts : NULL);
 158         for (n = 0; n < nfds; n++) {
 159                 struct uloop_fd_event *cur = &cur_fds[n];
 160                 struct uloop_fd *u = events[n].udata;
 161                 unsigned int ev = 0;
 162
 163                 cur->fd = u;
 164                 if (!u)
 165                         continue;
 166
 167                 if (events[n].flags & EV_ERROR) {
 168                         u->error = true;
 169                         uloop_fd_delete(u);
 170                 }
 171
 172                 if(events[n].filter == EVFILT_READ)
 173                         ev |= ULOOP_READ;
 174                 else if (events[n].filter == EVFILT_WRITE)
 175                         ev |= ULOOP_WRITE;
 176
 177                 if (events[n].flags & EV_EOF)
 178                         u->eof = true;
 179                 else if (!ev)
 180                         cur->fd = NULL;
 181
 182                 if (u->flags & ULOOP_EDGE_DEFER) {
 183                         u->flags &= ~ULOOP_EDGE_DEFER;
 184                         register_kevent(u, u->flags);
 185                 }
 186         }
 187         return nfds;
 188 }
 189
 190 #endif
 191
 192 #ifdef USE_EPOLL
 193
 194 /**
 195  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
 196  */
 197 #ifndef EPOLLRDHUP
 198 #define EPOLLRDHUP 0x2000
 199 #endif
 200
 201 int uloop_init(void)
 202 {
 203         if (poll_fd >= 0)
 204                 return 0;
 205
 206         poll_fd = epoll_create(32);
 207         if (poll_fd < 0)
 208                 return -1;
 209
 210         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
 211         return 0;
 212 }
 213
 214 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 215 {
 216         struct epoll_event ev;
 217         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 218
 219         memset(&ev, 0, sizeof(struct epoll_event));
 220
 221         if (flags & ULOOP_READ)
 222                 ev.events |= EPOLLIN | EPOLLRDHUP;
 223
 224         if (flags & ULOOP_WRITE)
 225                 ev.events |= EPOLLOUT;
 226
 227         if (flags & ULOOP_EDGE_TRIGGER)
 228                 ev.events |= EPOLLET;
 229
 230         ev.data.fd = fd->fd;
 231         ev.data.ptr = fd;
 232
 233         return epoll_ctl(poll_fd, op, fd->fd, &ev);
 234 }
 235
 236 static struct epoll_event events[ULOOP_MAX_EVENTS];
 237
 238 static int __uloop_fd_delete(struct uloop_fd *sock)
 239 {
 240         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
 241 }
 242
 243 static int uloop_fetch_events(int timeout)
 244 {
 245         int n, nfds;
 246
 247         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
 248         for (n = 0; n < nfds; ++n) {
 249                 struct uloop_fd_event *cur = &cur_fds[n];
 250                 struct uloop_fd *u = events[n].data.ptr;
 251                 unsigned int ev = 0;
 252
 253                 cur->fd = u;
 254                 if (!u)
 255                         continue;
 256
 257                 if (events[n].events & (EPOLLERR|EPOLLHUP)) {
 258                         u->error = true;
 259                         uloop_fd_delete(u);
 260                 }
 261
 262                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 263                         cur->fd = NULL;
 264                         continue;
 265                 }
 266
 267                 if(events[n].events & EPOLLRDHUP)
 268                         u->eof = true;
 269
 270                 if(events[n].events & EPOLLIN)
 271                         ev |= ULOOP_READ;
 272
 273                 if(events[n].events & EPOLLOUT)
 274                         ev |= ULOOP_WRITE;
 275
 276                 cur->events = ev;
 277         }
 278
 279         return nfds;
 280 }
 281
 282 #endif
 283
 284 static void uloop_run_events(int timeout)
 285 {
 286         struct uloop_fd_event *cur;
 287         struct uloop_fd *fd;
 288
 289         if (!cur_nfds) {
 290                 cur_fd = 0;
 291                 cur_nfds = uloop_fetch_events(timeout);
 292                 if (cur_nfds < 0)
 293                         cur_nfds = 0;
 294         }
 295
 296         while (cur_nfds > 0) {
 297                 cur = &cur_fds[cur_fd++];
 298                 cur_nfds--;
 299
 300                 fd = cur->fd;
 301                 if (!fd)
 302                         continue;
 303
 304                 if (!fd->cb)
 305                         continue;
 306
 307                 fd->cb(fd, cur->events);
 308                 return;
 309         }
 310 }
 311
 312 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 313 {
 314         unsigned int fl;
 315         int ret;
 316
 317         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 318                 return uloop_fd_delete(sock);
 319
 320         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 321                 fl = fcntl(sock->fd, F_GETFL, 0);
 322                 fl |= O_NONBLOCK;
 323                 fcntl(sock->fd, F_SETFL, fl);
 324         }
 325
 326         ret = register_poll(sock, flags);
 327         if (ret < 0)
 328                 goto out;
 329
 330         sock->registered = true;
 331         sock->eof = false;
 332
 333 out:
 334         return ret;
 335 }
 336
 337 int uloop_fd_delete(struct uloop_fd *fd)
 338 {
 339         int i;
 340
 341         if (!fd->registered)
 342                 return 0;
 343
 344         for (i = 0; i < cur_nfds; i++) {
 345                 if (cur_fds[cur_fd + i].fd != fd)
 346                         continue;
 347
 348                 cur_fds[cur_fd + i].fd = NULL;
 349         }
 350         fd->registered = false;
 351         return __uloop_fd_delete(fd);
 352 }
 353
 354 static int tv_diff(struct timeval *t1, struct timeval *t2)
 355 {
 356         return
 357                 (t1->tv_sec - t2->tv_sec) * 1000 +
 358                 (t1->tv_usec - t2->tv_usec) / 1000;
 359 }
 360
 361 int uloop_timeout_add(struct uloop_timeout *timeout)
 362 {
 363         struct uloop_timeout *tmp;
 364         struct list_head *h = &timeouts;
 365
 366         if (timeout->pending)
 367                 return -1;
 368
 369         list_for_each_entry(tmp, &timeouts, list) {
 370                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 371                         h = &tmp->list;
 372                         break;
 373                 }
 374         }
 375
 376         list_add_tail(&timeout->list, h);
 377         timeout->pending = true;
 378
 379         return 0;
 380 }
 381
 382 static void uloop_gettime(struct timeval *tv)
 383 {
 384         struct timespec ts;
 385
 386         clock_gettime(CLOCK_MONOTONIC, &ts);
 387         tv->tv_sec = ts.tv_sec;
 388         tv->tv_usec = ts.tv_nsec / 1000;
 389 }
 390
 391 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 392 {
 393         struct timeval *time = &timeout->time;
 394
 395         if (timeout->pending)
 396                 uloop_timeout_cancel(timeout);
 397
 398         uloop_gettime(&timeout->time);
 399
 400         time->tv_sec += msecs / 1000;
 401         time->tv_usec += (msecs % 1000) * 1000;
 402
 403         if (time->tv_usec > 1000000) {
 404                 time->tv_sec++;
 405                 time->tv_usec %= 1000000;
 406         }
 407
 408         return uloop_timeout_add(timeout);
 409 }
 410
 411 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 412 {
 413         if (!timeout->pending)
 414                 return -1;
 415
 416         list_del(&timeout->list);
 417         timeout->pending = false;
 418
 419         return 0;
 420 }
 421
 422 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 423 {
 424         struct timeval now;
 425
 426         if (!timeout->pending)
 427                 return -1;
 428
 429         uloop_gettime(&now);
 430
 431         return tv_diff(&timeout->time, &now);
 432 }
 433
 434 int uloop_process_add(struct uloop_process *p)
 435 {
 436         struct uloop_process *tmp;
 437         struct list_head *h = &processes;
 438
 439         if (p->pending)
 440                 return -1;
 441
 442         list_for_each_entry(tmp, &processes, list) {
 443                 if (tmp->pid > p->pid) {
 444                         h = &tmp->list;
 445                         break;
 446                 }
 447         }
 448
 449         list_add_tail(&p->list, h);
 450         p->pending = true;
 451
 452         return 0;
 453 }
 454
 455 int uloop_process_delete(struct uloop_process *p)
 456 {
 457         if (!p->pending)
 458                 return -1;
 459
 460         list_del(&p->list);
 461         p->pending = false;
 462
 463         return 0;
 464 }
 465
 466 static void uloop_handle_processes(void)
 467 {
 468         struct uloop_process *p, *tmp;
 469         pid_t pid;
 470         int ret;
 471
 472         do_sigchld = false;
 473
 474         while (1) {
 475                 pid = waitpid(-1, &ret, WNOHANG);
 476                 if (pid <= 0)
 477                         return;
 478
 479                 list_for_each_entry_safe(p, tmp, &processes, list) {
 480                         if (p->pid < pid)
 481                                 continue;
 482
 483                         if (p->pid > pid)
 484                                 break;
 485
 486                         uloop_process_delete(p);
 487                         p->cb(p, ret);
 488                 }
 489         }
 490
 491 }
 492
 493 static void uloop_handle_sigint(int signo)
 494 {
 495         uloop_cancelled = true;
 496 }
 497
 498 static void uloop_sigchld(int signo)
 499 {
 500         do_sigchld = true;
 501 }
 502
 503 static void uloop_setup_signals(void)
 504 {
 505         struct sigaction s;
 506
 507         memset(&s, 0, sizeof(struct sigaction));
 508         s.sa_handler = uloop_handle_sigint;
 509         s.sa_flags = 0;
 510         sigaction(SIGINT, &s, NULL);
 511
 512         if (uloop_handle_sigchld) {
 513                 s.sa_handler = uloop_sigchld;
 514                 sigaction(SIGCHLD, &s, NULL);
 515         }
 516 }
 517
 518 static int uloop_get_next_timeout(struct timeval *tv)
 519 {
 520         struct uloop_timeout *timeout;
 521         int diff;
 522
 523         if (list_empty(&timeouts))
 524                 return -1;
 525
 526         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 527         diff = tv_diff(&timeout->time, tv);
 528         if (diff < 0)
 529                 return 0;
 530
 531         return diff;
 532 }
 533
 534 static void uloop_process_timeouts(struct timeval *tv)
 535 {
 536         struct uloop_timeout *t;
 537
 538         while (!list_empty(&timeouts)) {
 539                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 540
 541                 if (tv_diff(&t->time, tv) > 0)
 542                         break;
 543
 544                 uloop_timeout_cancel(t);
 545                 if (t->cb)
 546                         t->cb(t);
 547         }
 548 }
 549
 550 static void uloop_clear_timeouts(void)
 551 {
 552         struct uloop_timeout *t, *tmp;
 553
 554         list_for_each_entry_safe(t, tmp, &timeouts, list)
 555                 uloop_timeout_cancel(t);
 556 }
 557
 558 static void uloop_clear_processes(void)
 559 {
 560         struct uloop_process *p, *tmp;
 561
 562         list_for_each_entry_safe(p, tmp, &processes, list)
 563                 uloop_process_delete(p);
 564 }
 565
 566 void uloop_run(void)
 567 {
 568         struct timeval tv;
 569
 570         uloop_setup_signals();
 571         while(!uloop_cancelled)
 572         {
 573                 uloop_gettime(&tv);
 574                 uloop_process_timeouts(&tv);
 575                 if (uloop_cancelled)
 576                         break;
 577
 578                 if (do_sigchld)
 579                         uloop_handle_processes();
 580                 uloop_run_events(uloop_get_next_timeout(&tv));
 581         }
 582 }
 583
 584 void uloop_done(void)
 585 {
 586         if (poll_fd < 0)
 587                 return;
 588
 589         close(poll_fd);
 590         poll_fd = -1;
 591
 592         uloop_clear_timeouts();
 593         uloop_clear_processes();
 594 }