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                         u->flags |= ULOOP_EDGE_TRIGGER;
 185                         register_kevent(u, u->flags);
 186                 }
 187         }
 188         return nfds;
 189 }
 190
 191 #endif
 192
 193 #ifdef USE_EPOLL
 194
 195 /**
 196  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
 197  */
 198 #ifndef EPOLLRDHUP
 199 #define EPOLLRDHUP 0x2000
 200 #endif
 201
 202 int uloop_init(void)
 203 {
 204         if (poll_fd >= 0)
 205                 return 0;
 206
 207         poll_fd = epoll_create(32);
 208         if (poll_fd < 0)
 209                 return -1;
 210
 211         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
 212         return 0;
 213 }
 214
 215 static int register_poll(struct uloop_fd *fd, unsigned int flags)
 216 {
 217         struct epoll_event ev;
 218         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 219
 220         memset(&ev, 0, sizeof(struct epoll_event));
 221
 222         if (flags & ULOOP_READ)
 223                 ev.events |= EPOLLIN | EPOLLRDHUP;
 224
 225         if (flags & ULOOP_WRITE)
 226                 ev.events |= EPOLLOUT;
 227
 228         if (flags & ULOOP_EDGE_TRIGGER)
 229                 ev.events |= EPOLLET;
 230
 231         ev.data.fd = fd->fd;
 232         ev.data.ptr = fd;
 233         fd->flags = flags;
 234
 235         return epoll_ctl(poll_fd, op, fd->fd, &ev);
 236 }
 237
 238 static struct epoll_event events[ULOOP_MAX_EVENTS];
 239
 240 static int __uloop_fd_delete(struct uloop_fd *sock)
 241 {
 242         sock->flags = 0;
 243         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
 244 }
 245
 246 static int uloop_fetch_events(int timeout)
 247 {
 248         int n, nfds;
 249
 250         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
 251         for (n = 0; n < nfds; ++n) {
 252                 struct uloop_fd_event *cur = &cur_fds[n];
 253                 struct uloop_fd *u = events[n].data.ptr;
 254                 unsigned int ev = 0;
 255
 256                 cur->fd = u;
 257                 if (!u)
 258                         continue;
 259
 260                 if (events[n].events & (EPOLLERR|EPOLLHUP)) {
 261                         u->error = true;
 262                         uloop_fd_delete(u);
 263                 }
 264
 265                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 266                         cur->fd = NULL;
 267                         continue;
 268                 }
 269
 270                 if(events[n].events & EPOLLRDHUP)
 271                         u->eof = true;
 272
 273                 if(events[n].events & EPOLLIN)
 274                         ev |= ULOOP_READ;
 275
 276                 if(events[n].events & EPOLLOUT)
 277                         ev |= ULOOP_WRITE;
 278
 279                 cur->events = ev;
 280         }
 281
 282         return nfds;
 283 }
 284
 285 #endif
 286
 287 static void uloop_run_events(int timeout)
 288 {
 289         struct uloop_fd_event *cur;
 290         struct uloop_fd *fd;
 291
 292         if (!cur_nfds) {
 293                 cur_fd = 0;
 294                 cur_nfds = uloop_fetch_events(timeout);
 295                 if (cur_nfds < 0)
 296                         cur_nfds = 0;
 297         }
 298
 299         while (cur_nfds > 0) {
 300                 cur = &cur_fds[cur_fd++];
 301                 cur_nfds--;
 302
 303                 fd = cur->fd;
 304                 if (!fd)
 305                         continue;
 306
 307                 if (!fd->cb)
 308                         continue;
 309
 310                 fd->cb(fd, cur->events);
 311                 return;
 312         }
 313 }
 314
 315 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 316 {
 317         unsigned int fl;
 318         int ret;
 319
 320         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 321                 return uloop_fd_delete(sock);
 322
 323         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 324                 fl = fcntl(sock->fd, F_GETFL, 0);
 325                 fl |= O_NONBLOCK;
 326                 fcntl(sock->fd, F_SETFL, fl);
 327         }
 328
 329         ret = register_poll(sock, flags);
 330         if (ret < 0)
 331                 goto out;
 332
 333         sock->registered = true;
 334         sock->eof = false;
 335
 336 out:
 337         return ret;
 338 }
 339
 340 int uloop_fd_delete(struct uloop_fd *fd)
 341 {
 342         int i;
 343
 344         if (!fd->registered)
 345                 return 0;
 346
 347         for (i = 0; i < cur_nfds; i++) {
 348                 if (cur_fds[cur_fd + i].fd != fd)
 349                         continue;
 350
 351                 cur_fds[cur_fd + i].fd = NULL;
 352         }
 353         fd->registered = false;
 354         return __uloop_fd_delete(fd);
 355 }
 356
 357 static int tv_diff(struct timeval *t1, struct timeval *t2)
 358 {
 359         return
 360                 (t1->tv_sec - t2->tv_sec) * 1000 +
 361                 (t1->tv_usec - t2->tv_usec) / 1000;
 362 }
 363
 364 int uloop_timeout_add(struct uloop_timeout *timeout)
 365 {
 366         struct uloop_timeout *tmp;
 367         struct list_head *h = &timeouts;
 368
 369         if (timeout->pending)
 370                 return -1;
 371
 372         list_for_each_entry(tmp, &timeouts, list) {
 373                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 374                         h = &tmp->list;
 375                         break;
 376                 }
 377         }
 378
 379         list_add_tail(&timeout->list, h);
 380         timeout->pending = true;
 381
 382         return 0;
 383 }
 384
 385 static void uloop_gettime(struct timeval *tv)
 386 {
 387         struct timespec ts;
 388
 389         clock_gettime(CLOCK_MONOTONIC, &ts);
 390         tv->tv_sec = ts.tv_sec;
 391         tv->tv_usec = ts.tv_nsec / 1000;
 392 }
 393
 394 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 395 {
 396         struct timeval *time = &timeout->time;
 397
 398         if (timeout->pending)
 399                 uloop_timeout_cancel(timeout);
 400
 401         uloop_gettime(&timeout->time);
 402
 403         time->tv_sec += msecs / 1000;
 404         time->tv_usec += (msecs % 1000) * 1000;
 405
 406         if (time->tv_usec > 1000000) {
 407                 time->tv_sec++;
 408                 time->tv_usec %= 1000000;
 409         }
 410
 411         return uloop_timeout_add(timeout);
 412 }
 413
 414 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 415 {
 416         if (!timeout->pending)
 417                 return -1;
 418
 419         list_del(&timeout->list);
 420         timeout->pending = false;
 421
 422         return 0;
 423 }
 424
 425 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 426 {
 427         struct timeval now;
 428
 429         if (!timeout->pending)
 430                 return -1;
 431
 432         uloop_gettime(&now);
 433
 434         return tv_diff(&timeout->time, &now);
 435 }
 436
 437 int uloop_process_add(struct uloop_process *p)
 438 {
 439         struct uloop_process *tmp;
 440         struct list_head *h = &processes;
 441
 442         if (p->pending)
 443                 return -1;
 444
 445         list_for_each_entry(tmp, &processes, list) {
 446                 if (tmp->pid > p->pid) {
 447                         h = &tmp->list;
 448                         break;
 449                 }
 450         }
 451
 452         list_add_tail(&p->list, h);
 453         p->pending = true;
 454
 455         return 0;
 456 }
 457
 458 int uloop_process_delete(struct uloop_process *p)
 459 {
 460         if (!p->pending)
 461                 return -1;
 462
 463         list_del(&p->list);
 464         p->pending = false;
 465
 466         return 0;
 467 }
 468
 469 static void uloop_handle_processes(void)
 470 {
 471         struct uloop_process *p, *tmp;
 472         pid_t pid;
 473         int ret;
 474
 475         do_sigchld = false;
 476
 477         while (1) {
 478                 pid = waitpid(-1, &ret, WNOHANG);
 479                 if (pid <= 0)
 480                         return;
 481
 482                 list_for_each_entry_safe(p, tmp, &processes, list) {
 483                         if (p->pid < pid)
 484                                 continue;
 485
 486                         if (p->pid > pid)
 487                                 break;
 488
 489                         uloop_process_delete(p);
 490                         p->cb(p, ret);
 491                 }
 492         }
 493
 494 }
 495
 496 static void uloop_handle_sigint(int signo)
 497 {
 498         uloop_cancelled = true;
 499 }
 500
 501 static void uloop_sigchld(int signo)
 502 {
 503         do_sigchld = true;
 504 }
 505
 506 static void uloop_setup_signals(void)
 507 {
 508         struct sigaction s;
 509
 510         memset(&s, 0, sizeof(struct sigaction));
 511         s.sa_handler = uloop_handle_sigint;
 512         s.sa_flags = 0;
 513         sigaction(SIGINT, &s, NULL);
 514
 515         if (uloop_handle_sigchld) {
 516                 s.sa_handler = uloop_sigchld;
 517                 sigaction(SIGCHLD, &s, NULL);
 518         }
 519 }
 520
 521 static int uloop_get_next_timeout(struct timeval *tv)
 522 {
 523         struct uloop_timeout *timeout;
 524         int diff;
 525
 526         if (list_empty(&timeouts))
 527                 return -1;
 528
 529         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 530         diff = tv_diff(&timeout->time, tv);
 531         if (diff < 0)
 532                 return 0;
 533
 534         return diff;
 535 }
 536
 537 static void uloop_process_timeouts(struct timeval *tv)
 538 {
 539         struct uloop_timeout *t;
 540
 541         while (!list_empty(&timeouts)) {
 542                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 543
 544                 if (tv_diff(&t->time, tv) > 0)
 545                         break;
 546
 547                 uloop_timeout_cancel(t);
 548                 if (t->cb)
 549                         t->cb(t);
 550         }
 551 }
 552
 553 static void uloop_clear_timeouts(void)
 554 {
 555         struct uloop_timeout *t, *tmp;
 556
 557         list_for_each_entry_safe(t, tmp, &timeouts, list)
 558                 uloop_timeout_cancel(t);
 559 }
 560
 561 static void uloop_clear_processes(void)
 562 {
 563         struct uloop_process *p, *tmp;
 564
 565         list_for_each_entry_safe(p, tmp, &processes, list)
 566                 uloop_process_delete(p);
 567 }
 568
 569 void uloop_run(void)
 570 {
 571         struct timeval tv;
 572
 573         uloop_setup_signals();
 574         while(!uloop_cancelled)
 575         {
 576                 uloop_gettime(&tv);
 577                 uloop_process_timeouts(&tv);
 578                 if (uloop_cancelled)
 579                         break;
 580
 581                 if (do_sigchld)
 582                         uloop_handle_processes();
 583                 uloop_run_events(uloop_get_next_timeout(&tv));
 584         }
 585 }
 586
 587 void uloop_done(void)
 588 {
 589         if (poll_fd < 0)
 590                 return;
 591
 592         close(poll_fd);
 593         poll_fd = -1;
 594
 595         uloop_clear_timeouts();
 596         uloop_clear_processes();
 597 }