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 #include <limits.h>
  30
  31 #include "uloop.h"
  32 #include "utils.h"
  33
  34 #ifdef USE_KQUEUE
  35 #include <sys/event.h>
  36 #endif
  37 #ifdef USE_EPOLL
  38 #include <sys/epoll.h>
  39 #endif
  40 #include <sys/wait.h>
  41
  42 struct uloop_fd_event {
  43         struct uloop_fd *fd;
  44         unsigned int events;
  45 };
  46
  47 struct uloop_fd_stack {
  48         struct uloop_fd_stack *next;
  49         struct uloop_fd *fd;
  50         unsigned int events;
  51 };
  52
  53 static struct uloop_fd_stack *fd_stack = NULL;
  54
  55 #define ULOOP_MAX_EVENTS 10
  56
  57 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
  58 static struct list_head processes = LIST_HEAD_INIT(processes);
  59
  60 static int poll_fd = -1;
  61 bool uloop_cancelled = false;
  62 bool uloop_handle_sigchld = true;
  63 static int uloop_status = 0;
  64 static bool do_sigchld = false;
  65
  66 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
  67 static int cur_fd, cur_nfds;
  68 static int uloop_run_depth = 0;
  69
  70 uloop_fd_handler uloop_fd_set_cb = NULL;
  71
  72 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  73
  74 #ifdef USE_KQUEUE
  75 #include "uloop-kqueue.c"
  76 #endif
  77
  78 #ifdef USE_EPOLL
  79 #include "uloop-epoll.c"
  80 #endif
  81
  82 static void waker_consume(struct uloop_fd *fd, unsigned int events)
  83 {
  84         char buf[4];
  85
  86         while (read(fd->fd, buf, 4) > 0)
  87                 ;
  88 }
  89
  90 static int waker_pipe = -1;
  91 static struct uloop_fd waker_fd = {
  92         .fd = -1,
  93         .cb = waker_consume,
  94 };
  95
  96 static void waker_init_fd(int fd)
  97 {
  98         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
  99         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
 100 }
 101
 102 static int waker_init(void)
 103 {
 104         int fds[2];
 105
 106         if (waker_pipe >= 0)
 107                 return 0;
 108
 109         if (pipe(fds) < 0)
 110                 return -1;
 111
 112         waker_init_fd(fds[0]);
 113         waker_init_fd(fds[1]);
 114         waker_pipe = fds[1];
 115
 116         waker_fd.fd = fds[0];
 117         waker_fd.cb = waker_consume;
 118         uloop_fd_add(&waker_fd, ULOOP_READ);
 119
 120         return 0;
 121 }
 122
 123 static void uloop_setup_signals(bool add);
 124
 125 int uloop_init(void)
 126 {
 127         if (uloop_init_pollfd() < 0)
 128                 return -1;
 129
 130         if (waker_init() < 0) {
 131                 uloop_done();
 132                 return -1;
 133         }
 134
 135         uloop_setup_signals(true);
 136
 137         return 0;
 138 }
 139
 140 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 141 {
 142         struct uloop_fd_stack *cur;
 143
 144         /*
 145          * Do not buffer events for level-triggered fds, they will keep firing.
 146          * Caller needs to take care of recursion issues.
 147          */
 148         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 149                 return false;
 150
 151         for (cur = fd_stack; cur; cur = cur->next) {
 152                 if (cur->fd != fd)
 153                         continue;
 154
 155                 if (events < 0)
 156                         cur->fd = NULL;
 157                 else
 158                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 159
 160                 return true;
 161         }
 162
 163         return false;
 164 }
 165
 166 static void uloop_run_events(int64_t timeout)
 167 {
 168         struct uloop_fd_event *cur;
 169         struct uloop_fd *fd;
 170
 171         if (!cur_nfds) {
 172                 cur_fd = 0;
 173                 cur_nfds = uloop_fetch_events(timeout);
 174                 if (cur_nfds < 0)
 175                         cur_nfds = 0;
 176         }
 177
 178         while (cur_nfds > 0) {
 179                 struct uloop_fd_stack stack_cur;
 180                 unsigned int events;
 181
 182                 cur = &cur_fds[cur_fd++];
 183                 cur_nfds--;
 184
 185                 fd = cur->fd;
 186                 events = cur->events;
 187                 if (!fd)
 188                         continue;
 189
 190                 if (!fd->cb)
 191                         continue;
 192
 193                 if (uloop_fd_stack_event(fd, cur->events))
 194                         continue;
 195
 196                 stack_cur.next = fd_stack;
 197                 stack_cur.fd = fd;
 198                 fd_stack = &stack_cur;
 199                 do {
 200                         stack_cur.events = 0;
 201                         fd->cb(fd, events);
 202                         events = stack_cur.events & ULOOP_EVENT_MASK;
 203                 } while (stack_cur.fd && events);
 204                 fd_stack = stack_cur.next;
 205
 206                 return;
 207         }
 208 }
 209
 210 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 211 {
 212         unsigned int fl;
 213         int ret;
 214
 215         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 216                 return uloop_fd_delete(sock);
 217
 218         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 219                 fl = fcntl(sock->fd, F_GETFL, 0);
 220                 fl |= O_NONBLOCK;
 221                 fcntl(sock->fd, F_SETFL, fl);
 222         }
 223
 224         ret = register_poll(sock, flags);
 225         if (ret < 0)
 226                 goto out;
 227
 228         if (uloop_fd_set_cb)
 229                 uloop_fd_set_cb(sock, flags);
 230
 231         sock->flags = flags;
 232         sock->registered = true;
 233         sock->eof = false;
 234         sock->error = false;
 235
 236 out:
 237         return ret;
 238 }
 239
 240 int uloop_fd_delete(struct uloop_fd *fd)
 241 {
 242         int i;
 243
 244         for (i = 0; i < cur_nfds; i++) {
 245                 if (cur_fds[cur_fd + i].fd != fd)
 246                         continue;
 247
 248                 cur_fds[cur_fd + i].fd = NULL;
 249         }
 250
 251         if (!fd->registered)
 252                 return 0;
 253
 254         if (uloop_fd_set_cb)
 255                 uloop_fd_set_cb(fd, 0);
 256
 257         fd->registered = false;
 258         fd->flags = 0;
 259         uloop_fd_stack_event(fd, -1);
 260         return __uloop_fd_delete(fd);
 261 }
 262
 263 static int64_t tv_diff(struct timeval *t1, struct timeval *t2)
 264 {
 265         return
 266                 (t1->tv_sec - t2->tv_sec) * 1000 +
 267                 (t1->tv_usec - t2->tv_usec) / 1000;
 268 }
 269
 270 int uloop_timeout_add(struct uloop_timeout *timeout)
 271 {
 272         struct uloop_timeout *tmp;
 273         struct list_head *h = &timeouts;
 274
 275         if (timeout->pending)
 276                 return -1;
 277
 278         list_for_each_entry(tmp, &timeouts, list) {
 279                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 280                         h = &tmp->list;
 281                         break;
 282                 }
 283         }
 284
 285         list_add_tail(&timeout->list, h);
 286         timeout->pending = true;
 287
 288         return 0;
 289 }
 290
 291 static void uloop_gettime(struct timeval *tv)
 292 {
 293         struct timespec ts;
 294
 295         clock_gettime(CLOCK_MONOTONIC, &ts);
 296         tv->tv_sec = ts.tv_sec;
 297         tv->tv_usec = ts.tv_nsec / 1000;
 298 }
 299
 300 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 301 {
 302         struct timeval *time = &timeout->time;
 303
 304         if (timeout->pending)
 305                 uloop_timeout_cancel(timeout);
 306
 307         uloop_gettime(time);
 308
 309         time->tv_sec += msecs / 1000;
 310         time->tv_usec += (msecs % 1000) * 1000;
 311
 312         if (time->tv_usec > 1000000) {
 313                 time->tv_sec++;
 314                 time->tv_usec -= 1000000;
 315         }
 316
 317         return uloop_timeout_add(timeout);
 318 }
 319
 320 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 321 {
 322         if (!timeout->pending)
 323                 return -1;
 324
 325         list_del(&timeout->list);
 326         timeout->pending = false;
 327
 328         return 0;
 329 }
 330
 331 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 332 {
 333         int64_t td;
 334         struct timeval now;
 335
 336         if (!timeout->pending)
 337                 return -1;
 338
 339         uloop_gettime(&now);
 340
 341         td = tv_diff(&timeout->time, &now);
 342
 343         if (td > INT_MAX)
 344                 return INT_MAX;
 345         else if (td < INT_MIN)
 346                 return INT_MIN;
 347         else
 348                 return (int)td;
 349 }
 350
 351 int64_t uloop_timeout_remaining64(struct uloop_timeout *timeout)
 352 {
 353         struct timeval now;
 354
 355         if (!timeout->pending)
 356                 return -1;
 357
 358         uloop_gettime(&now);
 359
 360         return tv_diff(&timeout->time, &now);
 361 }
 362
 363 int uloop_process_add(struct uloop_process *p)
 364 {
 365         struct uloop_process *tmp;
 366         struct list_head *h = &processes;
 367
 368         if (p->pending)
 369                 return -1;
 370
 371         list_for_each_entry(tmp, &processes, list) {
 372                 if (tmp->pid > p->pid) {
 373                         h = &tmp->list;
 374                         break;
 375                 }
 376         }
 377
 378         list_add_tail(&p->list, h);
 379         p->pending = true;
 380
 381         return 0;
 382 }
 383
 384 int uloop_process_delete(struct uloop_process *p)
 385 {
 386         if (!p->pending)
 387                 return -1;
 388
 389         list_del(&p->list);
 390         p->pending = false;
 391
 392         return 0;
 393 }
 394
 395 static void uloop_handle_processes(void)
 396 {
 397         struct uloop_process *p, *tmp;
 398         pid_t pid;
 399         int ret;
 400
 401         do_sigchld = false;
 402
 403         while (1) {
 404                 pid = waitpid(-1, &ret, WNOHANG);
 405                 if (pid < 0 && errno == EINTR)
 406                         continue;
 407
 408                 if (pid <= 0)
 409                         return;
 410
 411                 list_for_each_entry_safe(p, tmp, &processes, list) {
 412                         if (p->pid < pid)
 413                                 continue;
 414
 415                         if (p->pid > pid)
 416                                 break;
 417
 418                         uloop_process_delete(p);
 419                         p->cb(p, ret);
 420                 }
 421         }
 422
 423 }
 424
 425 static void uloop_signal_wake(void)
 426 {
 427         do {
 428                 if (write(waker_pipe, "w", 1) < 0) {
 429                         if (errno == EINTR)
 430                                 continue;
 431                 }
 432                 break;
 433         } while (1);
 434 }
 435
 436 static void uloop_handle_sigint(int signo)
 437 {
 438         uloop_status = signo;
 439         uloop_cancelled = true;
 440         uloop_signal_wake();
 441 }
 442
 443 static void uloop_sigchld(int signo)
 444 {
 445         do_sigchld = true;
 446         uloop_signal_wake();
 447 }
 448
 449 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 450 {
 451         struct sigaction s;
 452         struct sigaction *act;
 453
 454         act = NULL;
 455         sigaction(signum, NULL, &s);
 456
 457         if (add) {
 458                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 459                         memcpy(old, &s, sizeof(struct sigaction));
 460                         s.sa_handler = handler;
 461                         s.sa_flags = 0;
 462                         act = &s;
 463                 }
 464         }
 465         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 466                         act = old;
 467         }
 468
 469         if (act != NULL)
 470                 sigaction(signum, act, NULL);
 471 }
 472
 473 static void uloop_ignore_signal(int signum, bool ignore)
 474 {
 475         struct sigaction s;
 476         void *new_handler = NULL;
 477
 478         sigaction(signum, NULL, &s);
 479
 480         if (ignore) {
 481                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 482                         new_handler = SIG_IGN;
 483         } else {
 484                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 485                         new_handler = SIG_DFL;
 486         }
 487
 488         if (new_handler) {
 489                 s.sa_handler = new_handler;
 490                 s.sa_flags = 0;
 491                 sigaction(signum, &s, NULL);
 492         }
 493 }
 494
 495 static void uloop_setup_signals(bool add)
 496 {
 497         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 498
 499         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 500         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 501
 502         if (uloop_handle_sigchld)
 503                 uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
 504
 505         uloop_ignore_signal(SIGPIPE, add);
 506 }
 507
 508 int uloop_get_next_timeout(void)
 509 {
 510         struct uloop_timeout *timeout;
 511         struct timeval tv;
 512         int64_t diff;
 513
 514         if (list_empty(&timeouts))
 515                 return -1;
 516
 517         uloop_gettime(&tv);
 518
 519         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
 520         diff = tv_diff(&timeout->time, &tv);
 521         if (diff < 0)
 522                 return 0;
 523         if (diff > INT_MAX)
 524                 return INT_MAX;
 525
 526         return diff;
 527 }
 528
 529 static void uloop_process_timeouts(void)
 530 {
 531         struct uloop_timeout *t;
 532         struct timeval tv;
 533
 534         if (list_empty(&timeouts))
 535                 return;
 536
 537         uloop_gettime(&tv);
 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 bool uloop_cancelling(void)
 567 {
 568         return uloop_run_depth > 0 && uloop_cancelled;
 569 }
 570
 571 int uloop_run_timeout(int timeout)
 572 {
 573         int next_time = 0;
 574
 575         uloop_run_depth++;
 576
 577         uloop_status = 0;
 578         uloop_cancelled = false;
 579         do {
 580                 uloop_process_timeouts();
 581
 582                 if (do_sigchld)
 583                         uloop_handle_processes();
 584
 585                 if (uloop_cancelled)
 586                         break;
 587
 588                 next_time = uloop_get_next_timeout();
 589                 if (timeout >= 0 && (next_time < 0 || timeout < next_time))
 590                                 next_time = timeout;
 591                 uloop_run_events(next_time);
 592         } while (!uloop_cancelled && timeout < 0);
 593
 594         --uloop_run_depth;
 595
 596         return uloop_status;
 597 }
 598
 599 void uloop_done(void)
 600 {
 601         uloop_setup_signals(false);
 602
 603         if (poll_fd >= 0) {
 604                 close(poll_fd);
 605                 poll_fd = -1;
 606         }
 607
 608         if (waker_pipe >= 0) {
 609                 uloop_fd_delete(&waker_fd);
 610                 close(waker_pipe);
 611                 close(waker_fd.fd);
 612                 waker_pipe = -1;
 613         }
 614
 615         uloop_clear_timeouts();
 616         uloop_clear_processes();
 617 }