uloop.c

   1 /*
   2  * uloop - event loop implementation
   3  *
   4  * Copyright (C) 2010-2016 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 static bool do_sigchld = false;
  62
  63 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  64 static int cur_fd, cur_nfds;
  65
  66 #ifdef USE_KQUEUE
  67 #include "uloop-kqueue.c"
  68 #endif
  69
  70 #ifdef USE_EPOLL
  71
  72 /**
  73  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
  74  */
  75 #ifndef EPOLLRDHUP
  76 #define EPOLLRDHUP 0x2000
  77 #endif
  78
  79 int uloop_init(void)
  80 {
  81         if (poll_fd >= 0)
  82                 return 0;
  83
  84         poll_fd = epoll_create(32);
  85         if (poll_fd < 0)
  86                 return -1;
  87
  88         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
  89         return 0;
  90 }
  91
  92 static int register_poll(struct uloop_fd *fd, unsigned int flags)
  93 {
  94         struct epoll_event ev;
  95         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
  96
  97         memset(&ev, 0, sizeof(struct epoll_event));
  98
  99         if (flags & ULOOP_READ)
 100                 ev.events |= EPOLLIN | EPOLLRDHUP;
 101
 102         if (flags & ULOOP_WRITE)
 103                 ev.events |= EPOLLOUT;
 104
 105         if (flags & ULOOP_EDGE_TRIGGER)
 106                 ev.events |= EPOLLET;
 107
 108         ev.data.fd = fd->fd;
 109         ev.data.ptr = fd;
 110         fd->flags = flags;
 111
 112         return epoll_ctl(poll_fd, op, fd->fd, &ev);
 113 }
 114
 115 static struct epoll_event events[ULOOP_MAX_EVENTS];
 116
 117 static int __uloop_fd_delete(struct uloop_fd *sock)
 118 {
 119         sock->flags = 0;
 120         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
 121 }
 122
 123 static int uloop_fetch_events(int timeout)
 124 {
 125         int n, nfds;
 126
 127         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
 128         for (n = 0; n < nfds; ++n) {
 129                 struct uloop_fd_event *cur = &cur_fds[n];
 130                 struct uloop_fd *u = events[n].data.ptr;
 131                 unsigned int ev = 0;
 132
 133                 cur->fd = u;
 134                 if (!u)
 135                         continue;
 136
 137                 if (events[n].events & (EPOLLERR|EPOLLHUP)) {
 138                         u->error = true;
 139                         if (!(u->flags & ULOOP_ERROR_CB))
 140                                 uloop_fd_delete(u);
 141                 }
 142
 143                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
 144                         cur->fd = NULL;
 145                         continue;
 146                 }
 147
 148                 if(events[n].events & EPOLLRDHUP)
 149                         u->eof = true;
 150
 151                 if(events[n].events & EPOLLIN)
 152                         ev |= ULOOP_READ;
 153
 154                 if(events[n].events & EPOLLOUT)
 155                         ev |= ULOOP_WRITE;
 156
 157                 cur->events = ev;
 158         }
 159
 160         return nfds;
 161 }
 162
 163 #endif
 164
 165 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 166 {
 167         struct uloop_fd_stack *cur;
 168
 169         /*
 170          * Do not buffer events for level-triggered fds, they will keep firing.
 171          * Caller needs to take care of recursion issues.
 172          */
 173         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 174                 return false;
 175
 176         for (cur = fd_stack; cur; cur = cur->next) {
 177                 if (cur->fd != fd)
 178                         continue;
 179
 180                 if (events < 0)
 181                         cur->fd = NULL;
 182                 else
 183                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 184
 185                 return true;
 186         }
 187
 188         return false;
 189 }
 190
 191 static void uloop_run_events(int timeout)
 192 {
 193         struct uloop_fd_event *cur;
 194         struct uloop_fd *fd;
 195
 196         if (!cur_nfds) {
 197                 cur_fd = 0;
 198                 cur_nfds = uloop_fetch_events(timeout);
 199                 if (cur_nfds < 0)
 200                         cur_nfds = 0;
 201         }
 202
 203         while (cur_nfds > 0) {
 204                 struct uloop_fd_stack stack_cur;
 205                 unsigned int events;
 206
 207                 cur = &cur_fds[cur_fd++];
 208                 cur_nfds--;
 209
 210                 fd = cur->fd;
 211                 events = cur->events;
 212                 if (!fd)
 213                         continue;
 214
 215                 if (!fd->cb)
 216                         continue;
 217
 218                 if (uloop_fd_stack_event(fd, cur->events))
 219                         continue;
 220
 221                 stack_cur.next = fd_stack;
 222                 stack_cur.fd = fd;
 223                 fd_stack = &stack_cur;
 224                 do {
 225                         stack_cur.events = 0;
 226                         fd->cb(fd, events);
 227                         events = stack_cur.events & ULOOP_EVENT_MASK;
 228                 } while (stack_cur.fd && events);
 229                 fd_stack = stack_cur.next;
 230
 231                 return;
 232         }
 233 }
 234
 235 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 236 {
 237         unsigned int fl;
 238         int ret;
 239
 240         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 241                 return uloop_fd_delete(sock);
 242
 243         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 244                 fl = fcntl(sock->fd, F_GETFL, 0);
 245                 fl |= O_NONBLOCK;
 246                 fcntl(sock->fd, F_SETFL, fl);
 247         }
 248
 249         ret = register_poll(sock, flags);
 250         if (ret < 0)
 251                 goto out;
 252
 253         sock->registered = true;
 254         sock->eof = false;
 255         sock->error = false;
 256
 257 out:
 258         return ret;
 259 }
 260
 261 int uloop_fd_delete(struct uloop_fd *fd)
 262 {
 263         int i;
 264
 265         for (i = 0; i < cur_nfds; i++) {
 266                 if (cur_fds[cur_fd + i].fd != fd)
 267                         continue;
 268
 269                 cur_fds[cur_fd + i].fd = NULL;
 270         }
 271
 272         if (!fd->registered)
 273                 return 0;
 274
 275         fd->registered = false;
 276         uloop_fd_stack_event(fd, -1);
 277         return __uloop_fd_delete(fd);
 278 }
 279
 280 static int tv_diff(struct timeval *t1, struct timeval *t2)
 281 {
 282         return
 283                 (t1->tv_sec - t2->tv_sec) * 1000 +
 284                 (t1->tv_usec - t2->tv_usec) / 1000;
 285 }
 286
 287 int uloop_timeout_add(struct uloop_timeout *timeout)
 288 {
 289         struct uloop_timeout *tmp;
 290         struct list_head *h = &timeouts;
 291
 292         if (timeout->pending)
 293                 return -1;
 294
 295         list_for_each_entry(tmp, &timeouts, list) {
 296                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 297                         h = &tmp->list;
 298                         break;
 299                 }
 300         }
 301
 302         list_add_tail(&timeout->list, h);
 303         timeout->pending = true;
 304
 305         return 0;
 306 }
 307
 308 static void uloop_gettime(struct timeval *tv)
 309 {
 310         struct timespec ts;
 311
 312         clock_gettime(CLOCK_MONOTONIC, &ts);
 313         tv->tv_sec = ts.tv_sec;
 314         tv->tv_usec = ts.tv_nsec / 1000;
 315 }
 316
 317 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 318 {
 319         struct timeval *time = &timeout->time;
 320
 321         if (timeout->pending)
 322                 uloop_timeout_cancel(timeout);
 323
 324         uloop_gettime(time);
 325
 326         time->tv_sec += msecs / 1000;
 327         time->tv_usec += (msecs % 1000) * 1000;
 328
 329         if (time->tv_usec > 1000000) {
 330                 time->tv_sec++;
 331                 time->tv_usec -= 1000000;
 332         }
 333
 334         return uloop_timeout_add(timeout);
 335 }
 336
 337 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 338 {
 339         if (!timeout->pending)
 340                 return -1;
 341
 342         list_del(&timeout->list);
 343         timeout->pending = false;
 344
 345         return 0;
 346 }
 347
 348 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 349 {
 350         struct timeval now;
 351
 352         if (!timeout->pending)
 353                 return -1;
 354
 355         uloop_gettime(&now);
 356
 357         return tv_diff(&timeout->time, &now);
 358 }
 359
 360 int uloop_process_add(struct uloop_process *p)
 361 {
 362         struct uloop_process *tmp;
 363         struct list_head *h = &processes;
 364
 365         if (p->pending)
 366                 return -1;
 367
 368         list_for_each_entry(tmp, &processes, list) {
 369                 if (tmp->pid > p->pid) {
 370                         h = &tmp->list;
 371                         break;
 372                 }
 373         }
 374
 375         list_add_tail(&p->list, h);
 376         p->pending = true;
 377
 378         return 0;
 379 }
 380
 381 int uloop_process_delete(struct uloop_process *p)
 382 {
 383         if (!p->pending)
 384                 return -1;
 385
 386         list_del(&p->list);
 387         p->pending = false;
 388
 389         return 0;
 390 }
 391
 392 static void uloop_handle_processes(void)
 393 {
 394         struct uloop_process *p, *tmp;
 395         pid_t pid;
 396         int ret;
 397
 398         do_sigchld = false;
 399
 400         while (1) {
 401                 pid = waitpid(-1, &ret, WNOHANG);
 402                 if (pid <= 0)
 403                         return;
 404
 405                 list_for_each_entry_safe(p, tmp, &processes, list) {
 406                         if (p->pid < pid)
 407                                 continue;
 408
 409                         if (p->pid > pid)
 410                                 break;
 411
 412                         uloop_process_delete(p);
 413                         p->cb(p, ret);
 414                 }
 415         }
 416
 417 }
 418
 419 static void uloop_handle_sigint(int signo)
 420 {
 421         uloop_cancelled = true;
 422 }
 423
 424 static void uloop_sigchld(int signo)
 425 {
 426         do_sigchld = true;
 427 }
 428
 429 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 430 {
 431         struct sigaction s;
 432         struct sigaction *act;
 433
 434         act = NULL;
 435         sigaction(signum, NULL, &s);
 436
 437         if (add) {
 438                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 439                         memcpy(old, &s, sizeof(struct sigaction));
 440                         s.sa_handler = handler;
 441                         s.sa_flags = 0;
 442                         act = &s;
 443                 }
 444         }
 445         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 446                         act = old;
 447         }
 448
 449         if (act != NULL)
 450                 sigaction(signum, act, NULL);
 451 }
 452
 453 static void uloop_ignore_signal(int signum, bool ignore)
 454 {
 455         struct sigaction s;
 456         void *new_handler = NULL;
 457
 458         sigaction(signum, NULL, &s);
 459
 460         if (ignore) {
 461                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 462                         new_handler = SIG_IGN;
 463         } else {
 464                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 465                         new_handler = SIG_DFL;
 466         }
 467
 468         if (new_handler) {
 469                 s.sa_handler = new_handler;
 470                 s.sa_flags = 0;
 471                 sigaction(signum, &s, NULL);
 472         }
 473 }
 474
 475 static void uloop_setup_signals(bool add)
 476 {
 477         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 478
 479         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 480         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 481         uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 482
 483         uloop_ignore_signal(SIGPIPE, add);
 484 }
 485
 486 static int uloop_get_next_timeout(struct timeval *tv)
 487 {
 488         struct uloop_timeout *timeout;
 489         int diff;
 490
 491         if (list_empty(&timeouts))
 492                 return -1;
 493
 494         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 495         diff = tv_diff(&timeout->time, tv);
 496         if (diff < 0)
 497                 return 0;
 498
 499         return diff;
 500 }
 501
 502 static void uloop_process_timeouts(struct timeval *tv)
 503 {
 504         struct uloop_timeout *t;
 505
 506         while (!list_empty(&timeouts)) {
 507                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 508
 509                 if (tv_diff(&t->time, tv) > 0)
 510                         break;
 511
 512                 uloop_timeout_cancel(t);
 513                 if (t->cb)
 514                         t->cb(t);
 515         }
 516 }
 517
 518 static void uloop_clear_timeouts(void)
 519 {
 520         struct uloop_timeout *t, *tmp;
 521
 522         list_for_each_entry_safe(t, tmp, &timeouts, list)
 523                 uloop_timeout_cancel(t);
 524 }
 525
 526 static void uloop_clear_processes(void)
 527 {
 528         struct uloop_process *p, *tmp;
 529
 530         list_for_each_entry_safe(p, tmp, &processes, list)
 531                 uloop_process_delete(p);
 532 }
 533
 534 void uloop_run(void)
 535 {
 536         static int recursive_calls = 0;
 537         struct timeval tv;
 538
 539         /*
 540          * Handlers are only updated for the first call to uloop_run() (and restored
 541          * when this call is done).
 542          */
 543         if (!recursive_calls++)
 544                 uloop_setup_signals(true);
 545
 546         uloop_cancelled = false;
 547         while(!uloop_cancelled)
 548         {
 549                 uloop_gettime(&tv);
 550                 uloop_process_timeouts(&tv);
 551
 552                 if (do_sigchld)
 553                         uloop_handle_processes();
 554
 555                 if (uloop_cancelled)
 556                         break;
 557
 558                 uloop_gettime(&tv);
 559                 uloop_run_events(uloop_get_next_timeout(&tv));
 560         }
 561
 562         if (!--recursive_calls)
 563                 uloop_setup_signals(false);
 564 }
 565
 566 void uloop_done(void)
 567 {
 568         if (poll_fd < 0)
 569                 return;
 570
 571         close(poll_fd);
 572         poll_fd = -1;
 573
 574         uloop_clear_timeouts();
 575         uloop_clear_processes();
 576 }