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 int uloop_status = 0;
  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 static int uloop_run_depth = 0;
  67
  68 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  69
  70 #ifdef USE_KQUEUE
  71 #include "uloop-kqueue.c"
  72 #endif
  73
  74 #ifdef USE_EPOLL
  75 #include "uloop-epoll.c"
  76 #endif
  77
  78 static void waker_consume(struct uloop_fd *fd, unsigned int events)
  79 {
  80         char buf[4];
  81
  82         while (read(fd->fd, buf, 4) > 0)
  83                 ;
  84 }
  85
  86 static int waker_pipe = -1;
  87 static struct uloop_fd waker_fd = {
  88         .fd = -1,
  89         .cb = waker_consume,
  90 };
  91
  92 static void waker_init_fd(int fd)
  93 {
  94         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
  95         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
  96 }
  97
  98 static int waker_init(void)
  99 {
 100         int fds[2];
 101
 102         if (waker_pipe >= 0)
 103                 return 0;
 104
 105         if (pipe(fds) < 0)
 106                 return -1;
 107
 108         waker_init_fd(fds[0]);
 109         waker_init_fd(fds[1]);
 110         waker_pipe = fds[1];
 111
 112         waker_fd.fd = fds[0];
 113         waker_fd.cb = waker_consume;
 114         uloop_fd_add(&waker_fd, ULOOP_READ);
 115
 116         return 0;
 117 }
 118
 119 static void uloop_setup_signals(bool add);
 120
 121 int uloop_init(void)
 122 {
 123         if (uloop_init_pollfd() < 0)
 124                 return -1;
 125
 126         if (waker_init() < 0) {
 127                 uloop_done();
 128                 return -1;
 129         }
 130
 131         uloop_setup_signals(true);
 132
 133         return 0;
 134 }
 135
 136 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 137 {
 138         struct uloop_fd_stack *cur;
 139
 140         /*
 141          * Do not buffer events for level-triggered fds, they will keep firing.
 142          * Caller needs to take care of recursion issues.
 143          */
 144         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 145                 return false;
 146
 147         for (cur = fd_stack; cur; cur = cur->next) {
 148                 if (cur->fd != fd)
 149                         continue;
 150
 151                 if (events < 0)
 152                         cur->fd = NULL;
 153                 else
 154                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 155
 156                 return true;
 157         }
 158
 159         return false;
 160 }
 161
 162 static void uloop_run_events(int timeout)
 163 {
 164         struct uloop_fd_event *cur;
 165         struct uloop_fd *fd;
 166
 167         if (!cur_nfds) {
 168                 cur_fd = 0;
 169                 cur_nfds = uloop_fetch_events(timeout);
 170                 if (cur_nfds < 0)
 171                         cur_nfds = 0;
 172         }
 173
 174         while (cur_nfds > 0) {
 175                 struct uloop_fd_stack stack_cur;
 176                 unsigned int events;
 177
 178                 cur = &cur_fds[cur_fd++];
 179                 cur_nfds--;
 180
 181                 fd = cur->fd;
 182                 events = cur->events;
 183                 if (!fd)
 184                         continue;
 185
 186                 if (!fd->cb)
 187                         continue;
 188
 189                 if (uloop_fd_stack_event(fd, cur->events))
 190                         continue;
 191
 192                 stack_cur.next = fd_stack;
 193                 stack_cur.fd = fd;
 194                 fd_stack = &stack_cur;
 195                 do {
 196                         stack_cur.events = 0;
 197                         fd->cb(fd, events);
 198                         events = stack_cur.events & ULOOP_EVENT_MASK;
 199                 } while (stack_cur.fd && events);
 200                 fd_stack = stack_cur.next;
 201
 202                 return;
 203         }
 204 }
 205
 206 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 207 {
 208         unsigned int fl;
 209         int ret;
 210
 211         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 212                 return uloop_fd_delete(sock);
 213
 214         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 215                 fl = fcntl(sock->fd, F_GETFL, 0);
 216                 fl |= O_NONBLOCK;
 217                 fcntl(sock->fd, F_SETFL, fl);
 218         }
 219
 220         ret = register_poll(sock, flags);
 221         if (ret < 0)
 222                 goto out;
 223
 224         sock->registered = true;
 225         sock->eof = false;
 226         sock->error = false;
 227
 228 out:
 229         return ret;
 230 }
 231
 232 int uloop_fd_delete(struct uloop_fd *fd)
 233 {
 234         int i;
 235
 236         for (i = 0; i < cur_nfds; i++) {
 237                 if (cur_fds[cur_fd + i].fd != fd)
 238                         continue;
 239
 240                 cur_fds[cur_fd + i].fd = NULL;
 241         }
 242
 243         if (!fd->registered)
 244                 return 0;
 245
 246         fd->registered = false;
 247         uloop_fd_stack_event(fd, -1);
 248         return __uloop_fd_delete(fd);
 249 }
 250
 251 static int tv_diff(struct timeval *t1, struct timeval *t2)
 252 {
 253         return
 254                 (t1->tv_sec - t2->tv_sec) * 1000 +
 255                 (t1->tv_usec - t2->tv_usec) / 1000;
 256 }
 257
 258 int uloop_timeout_add(struct uloop_timeout *timeout)
 259 {
 260         struct uloop_timeout *tmp;
 261         struct list_head *h = &timeouts;
 262
 263         if (timeout->pending)
 264                 return -1;
 265
 266         list_for_each_entry(tmp, &timeouts, list) {
 267                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 268                         h = &tmp->list;
 269                         break;
 270                 }
 271         }
 272
 273         list_add_tail(&timeout->list, h);
 274         timeout->pending = true;
 275
 276         return 0;
 277 }
 278
 279 static void uloop_gettime(struct timeval *tv)
 280 {
 281         struct timespec ts;
 282
 283         clock_gettime(CLOCK_MONOTONIC, &ts);
 284         tv->tv_sec = ts.tv_sec;
 285         tv->tv_usec = ts.tv_nsec / 1000;
 286 }
 287
 288 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 289 {
 290         struct timeval *time = &timeout->time;
 291
 292         if (timeout->pending)
 293                 uloop_timeout_cancel(timeout);
 294
 295         uloop_gettime(time);
 296
 297         time->tv_sec += msecs / 1000;
 298         time->tv_usec += (msecs % 1000) * 1000;
 299
 300         if (time->tv_usec > 1000000) {
 301                 time->tv_sec++;
 302                 time->tv_usec -= 1000000;
 303         }
 304
 305         return uloop_timeout_add(timeout);
 306 }
 307
 308 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 309 {
 310         if (!timeout->pending)
 311                 return -1;
 312
 313         list_del(&timeout->list);
 314         timeout->pending = false;
 315
 316         return 0;
 317 }
 318
 319 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 320 {
 321         struct timeval now;
 322
 323         if (!timeout->pending)
 324                 return -1;
 325
 326         uloop_gettime(&now);
 327
 328         return tv_diff(&timeout->time, &now);
 329 }
 330
 331 int uloop_process_add(struct uloop_process *p)
 332 {
 333         struct uloop_process *tmp;
 334         struct list_head *h = &processes;
 335
 336         if (p->pending)
 337                 return -1;
 338
 339         list_for_each_entry(tmp, &processes, list) {
 340                 if (tmp->pid > p->pid) {
 341                         h = &tmp->list;
 342                         break;
 343                 }
 344         }
 345
 346         list_add_tail(&p->list, h);
 347         p->pending = true;
 348
 349         return 0;
 350 }
 351
 352 int uloop_process_delete(struct uloop_process *p)
 353 {
 354         if (!p->pending)
 355                 return -1;
 356
 357         list_del(&p->list);
 358         p->pending = false;
 359
 360         return 0;
 361 }
 362
 363 static void uloop_handle_processes(void)
 364 {
 365         struct uloop_process *p, *tmp;
 366         pid_t pid;
 367         int ret;
 368
 369         do_sigchld = false;
 370
 371         while (1) {
 372                 pid = waitpid(-1, &ret, WNOHANG);
 373                 if (pid < 0 && errno == EINTR)
 374                         continue;
 375
 376                 if (pid <= 0)
 377                         return;
 378
 379                 list_for_each_entry_safe(p, tmp, &processes, list) {
 380                         if (p->pid < pid)
 381                                 continue;
 382
 383                         if (p->pid > pid)
 384                                 break;
 385
 386                         uloop_process_delete(p);
 387                         p->cb(p, ret);
 388                 }
 389         }
 390
 391 }
 392
 393 static void uloop_signal_wake(void)
 394 {
 395         do {
 396                 if (write(waker_pipe, "w", 1) < 0) {
 397                         if (errno == EINTR)
 398                                 continue;
 399                 }
 400                 break;
 401         } while (1);
 402 }
 403
 404 static void uloop_handle_sigint(int signo)
 405 {
 406         uloop_status = signo;
 407         uloop_cancelled = true;
 408         uloop_signal_wake();
 409 }
 410
 411 static void uloop_sigchld(int signo)
 412 {
 413         do_sigchld = true;
 414         uloop_signal_wake();
 415 }
 416
 417 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 418 {
 419         struct sigaction s;
 420         struct sigaction *act;
 421
 422         act = NULL;
 423         sigaction(signum, NULL, &s);
 424
 425         if (add) {
 426                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 427                         memcpy(old, &s, sizeof(struct sigaction));
 428                         s.sa_handler = handler;
 429                         s.sa_flags = 0;
 430                         act = &s;
 431                 }
 432         }
 433         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 434                         act = old;
 435         }
 436
 437         if (act != NULL)
 438                 sigaction(signum, act, NULL);
 439 }
 440
 441 static void uloop_ignore_signal(int signum, bool ignore)
 442 {
 443         struct sigaction s;
 444         void *new_handler = NULL;
 445
 446         sigaction(signum, NULL, &s);
 447
 448         if (ignore) {
 449                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 450                         new_handler = SIG_IGN;
 451         } else {
 452                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 453                         new_handler = SIG_DFL;
 454         }
 455
 456         if (new_handler) {
 457                 s.sa_handler = new_handler;
 458                 s.sa_flags = 0;
 459                 sigaction(signum, &s, NULL);
 460         }
 461 }
 462
 463 static void uloop_setup_signals(bool add)
 464 {
 465         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 466
 467         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 468         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 469         uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 470
 471         uloop_ignore_signal(SIGPIPE, add);
 472 }
 473
 474 static int uloop_get_next_timeout(struct timeval *tv)
 475 {
 476         struct uloop_timeout *timeout;
 477         int diff;
 478
 479         if (list_empty(&timeouts))
 480                 return -1;
 481
 482         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 483         diff = tv_diff(&timeout->time, tv);
 484         if (diff < 0)
 485                 return 0;
 486
 487         return diff;
 488 }
 489
 490 static void uloop_process_timeouts(struct timeval *tv)
 491 {
 492         struct uloop_timeout *t;
 493
 494         while (!list_empty(&timeouts)) {
 495                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
 496
 497                 if (tv_diff(&t->time, tv) > 0)
 498                         break;
 499
 500                 uloop_timeout_cancel(t);
 501                 if (t->cb)
 502                         t->cb(t);
 503         }
 504 }
 505
 506 static void uloop_clear_timeouts(void)
 507 {
 508         struct uloop_timeout *t, *tmp;
 509
 510         list_for_each_entry_safe(t, tmp, &timeouts, list)
 511                 uloop_timeout_cancel(t);
 512 }
 513
 514 static void uloop_clear_processes(void)
 515 {
 516         struct uloop_process *p, *tmp;
 517
 518         list_for_each_entry_safe(p, tmp, &processes, list)
 519                 uloop_process_delete(p);
 520 }
 521
 522 bool uloop_cancelling(void)
 523 {
 524         return uloop_run_depth > 0 && uloop_cancelled;
 525 }
 526
 527 int uloop_run_timeout(int timeout)
 528 {
 529         int next_time = 0;
 530         struct timeval tv;
 531
 532         uloop_run_depth++;
 533
 534         uloop_status = 0;
 535         uloop_cancelled = false;
 536         while (!uloop_cancelled)
 537         {
 538                 uloop_gettime(&tv);
 539                 uloop_process_timeouts(&tv);
 540
 541                 if (do_sigchld)
 542                         uloop_handle_processes();
 543
 544                 if (uloop_cancelled)
 545                         break;
 546
 547                 uloop_gettime(&tv);
 548
 549                 next_time = uloop_get_next_timeout(&tv);
 550                 if (timeout >= 0 && timeout < next_time)
 551                         next_time = timeout;
 552                 uloop_run_events(next_time);
 553         }
 554
 555         --uloop_run_depth;
 556
 557         return uloop_status;
 558 }
 559
 560 void uloop_done(void)
 561 {
 562         uloop_setup_signals(false);
 563
 564         if (poll_fd >= 0) {
 565                 close(poll_fd);
 566                 poll_fd = -1;
 567         }
 568
 569         if (waker_pipe >= 0) {
 570                 uloop_fd_delete(&waker_fd);
 571                 close(waker_pipe);
 572                 close(waker_fd.fd);
 573                 waker_pipe = -1;
 574         }
 575
 576         uloop_clear_timeouts();
 577         uloop_clear_processes();
 578 }