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 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
  71
  72 #ifdef USE_KQUEUE
  73 #include "uloop-kqueue.c"
  74 #endif
  75
  76 #ifdef USE_EPOLL
  77 #include "uloop-epoll.c"
  78 #endif
  79
  80 static void waker_consume(struct uloop_fd *fd, unsigned int events)
  81 {
  82         char buf[4];
  83
  84         while (read(fd->fd, buf, 4) > 0)
  85                 ;
  86 }
  87
  88 static int waker_pipe = -1;
  89 static struct uloop_fd waker_fd = {
  90         .fd = -1,
  91         .cb = waker_consume,
  92 };
  93
  94 static void waker_init_fd(int fd)
  95 {
  96         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
  97         fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
  98 }
  99
 100 static int waker_init(void)
 101 {
 102         int fds[2];
 103
 104         if (waker_pipe >= 0)
 105                 return 0;
 106
 107         if (pipe(fds) < 0)
 108                 return -1;
 109
 110         waker_init_fd(fds[0]);
 111         waker_init_fd(fds[1]);
 112         waker_pipe = fds[1];
 113
 114         waker_fd.fd = fds[0];
 115         waker_fd.cb = waker_consume;
 116         uloop_fd_add(&waker_fd, ULOOP_READ);
 117
 118         return 0;
 119 }
 120
 121 static void uloop_setup_signals(bool add);
 122
 123 int uloop_init(void)
 124 {
 125         if (uloop_init_pollfd() < 0)
 126                 return -1;
 127
 128         if (waker_init() < 0) {
 129                 uloop_done();
 130                 return -1;
 131         }
 132
 133         uloop_setup_signals(true);
 134
 135         return 0;
 136 }
 137
 138 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
 139 {
 140         struct uloop_fd_stack *cur;
 141
 142         /*
 143          * Do not buffer events for level-triggered fds, they will keep firing.
 144          * Caller needs to take care of recursion issues.
 145          */
 146         if (!(fd->flags & ULOOP_EDGE_TRIGGER))
 147                 return false;
 148
 149         for (cur = fd_stack; cur; cur = cur->next) {
 150                 if (cur->fd != fd)
 151                         continue;
 152
 153                 if (events < 0)
 154                         cur->fd = NULL;
 155                 else
 156                         cur->events |= events | ULOOP_EVENT_BUFFERED;
 157
 158                 return true;
 159         }
 160
 161         return false;
 162 }
 163
 164 static void uloop_run_events(int timeout)
 165 {
 166         struct uloop_fd_event *cur;
 167         struct uloop_fd *fd;
 168
 169         if (!cur_nfds) {
 170                 cur_fd = 0;
 171                 cur_nfds = uloop_fetch_events(timeout);
 172                 if (cur_nfds < 0)
 173                         cur_nfds = 0;
 174         }
 175
 176         while (cur_nfds > 0) {
 177                 struct uloop_fd_stack stack_cur;
 178                 unsigned int events;
 179
 180                 cur = &cur_fds[cur_fd++];
 181                 cur_nfds--;
 182
 183                 fd = cur->fd;
 184                 events = cur->events;
 185                 if (!fd)
 186                         continue;
 187
 188                 if (!fd->cb)
 189                         continue;
 190
 191                 if (uloop_fd_stack_event(fd, cur->events))
 192                         continue;
 193
 194                 stack_cur.next = fd_stack;
 195                 stack_cur.fd = fd;
 196                 fd_stack = &stack_cur;
 197                 do {
 198                         stack_cur.events = 0;
 199                         fd->cb(fd, events);
 200                         events = stack_cur.events & ULOOP_EVENT_MASK;
 201                 } while (stack_cur.fd && events);
 202                 fd_stack = stack_cur.next;
 203
 204                 return;
 205         }
 206 }
 207
 208 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 209 {
 210         unsigned int fl;
 211         int ret;
 212
 213         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
 214                 return uloop_fd_delete(sock);
 215
 216         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 217                 fl = fcntl(sock->fd, F_GETFL, 0);
 218                 fl |= O_NONBLOCK;
 219                 fcntl(sock->fd, F_SETFL, fl);
 220         }
 221
 222         ret = register_poll(sock, flags);
 223         if (ret < 0)
 224                 goto out;
 225
 226         sock->registered = true;
 227         sock->eof = false;
 228         sock->error = false;
 229
 230 out:
 231         return ret;
 232 }
 233
 234 int uloop_fd_delete(struct uloop_fd *fd)
 235 {
 236         int i;
 237
 238         for (i = 0; i < cur_nfds; i++) {
 239                 if (cur_fds[cur_fd + i].fd != fd)
 240                         continue;
 241
 242                 cur_fds[cur_fd + i].fd = NULL;
 243         }
 244
 245         if (!fd->registered)
 246                 return 0;
 247
 248         fd->registered = false;
 249         uloop_fd_stack_event(fd, -1);
 250         return __uloop_fd_delete(fd);
 251 }
 252
 253 static int64_t tv_diff(struct timeval *t1, struct timeval *t2)
 254 {
 255         return
 256                 (t1->tv_sec - t2->tv_sec) * 1000 +
 257                 (t1->tv_usec - t2->tv_usec) / 1000;
 258 }
 259
 260 int uloop_timeout_add(struct uloop_timeout *timeout)
 261 {
 262         struct uloop_timeout *tmp;
 263         struct list_head *h = &timeouts;
 264
 265         if (timeout->pending)
 266                 return -1;
 267
 268         list_for_each_entry(tmp, &timeouts, list) {
 269                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
 270                         h = &tmp->list;
 271                         break;
 272                 }
 273         }
 274
 275         list_add_tail(&timeout->list, h);
 276         timeout->pending = true;
 277
 278         return 0;
 279 }
 280
 281 static void uloop_gettime(struct timeval *tv)
 282 {
 283         struct timespec ts;
 284
 285         clock_gettime(CLOCK_MONOTONIC, &ts);
 286         tv->tv_sec = ts.tv_sec;
 287         tv->tv_usec = ts.tv_nsec / 1000;
 288 }
 289
 290 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
 291 {
 292         struct timeval *time = &timeout->time;
 293
 294         if (timeout->pending)
 295                 uloop_timeout_cancel(timeout);
 296
 297         uloop_gettime(time);
 298
 299         time->tv_sec += msecs / 1000;
 300         time->tv_usec += (msecs % 1000) * 1000;
 301
 302         if (time->tv_usec > 1000000) {
 303                 time->tv_sec++;
 304                 time->tv_usec -= 1000000;
 305         }
 306
 307         return uloop_timeout_add(timeout);
 308 }
 309
 310 int uloop_timeout_cancel(struct uloop_timeout *timeout)
 311 {
 312         if (!timeout->pending)
 313                 return -1;
 314
 315         list_del(&timeout->list);
 316         timeout->pending = false;
 317
 318         return 0;
 319 }
 320
 321 int uloop_timeout_remaining(struct uloop_timeout *timeout)
 322 {
 323         int64_t td;
 324         struct timeval now;
 325
 326         if (!timeout->pending)
 327                 return -1;
 328
 329         uloop_gettime(&now);
 330
 331         td = tv_diff(&timeout->time, &now);
 332
 333         if (td > INT_MAX)
 334                 return INT_MAX;
 335         else if (td < INT_MIN)
 336                 return INT_MIN;
 337         else
 338                 return (int)td;
 339 }
 340
 341 int uloop_process_add(struct uloop_process *p)
 342 {
 343         struct uloop_process *tmp;
 344         struct list_head *h = &processes;
 345
 346         if (p->pending)
 347                 return -1;
 348
 349         list_for_each_entry(tmp, &processes, list) {
 350                 if (tmp->pid > p->pid) {
 351                         h = &tmp->list;
 352                         break;
 353                 }
 354         }
 355
 356         list_add_tail(&p->list, h);
 357         p->pending = true;
 358
 359         return 0;
 360 }
 361
 362 int uloop_process_delete(struct uloop_process *p)
 363 {
 364         if (!p->pending)
 365                 return -1;
 366
 367         list_del(&p->list);
 368         p->pending = false;
 369
 370         return 0;
 371 }
 372
 373 static void uloop_handle_processes(void)
 374 {
 375         struct uloop_process *p, *tmp;
 376         pid_t pid;
 377         int ret;
 378
 379         do_sigchld = false;
 380
 381         while (1) {
 382                 pid = waitpid(-1, &ret, WNOHANG);
 383                 if (pid < 0 && errno == EINTR)
 384                         continue;
 385
 386                 if (pid <= 0)
 387                         return;
 388
 389                 list_for_each_entry_safe(p, tmp, &processes, list) {
 390                         if (p->pid < pid)
 391                                 continue;
 392
 393                         if (p->pid > pid)
 394                                 break;
 395
 396                         uloop_process_delete(p);
 397                         p->cb(p, ret);
 398                 }
 399         }
 400
 401 }
 402
 403 static void uloop_signal_wake(void)
 404 {
 405         do {
 406                 if (write(waker_pipe, "w", 1) < 0) {
 407                         if (errno == EINTR)
 408                                 continue;
 409                 }
 410                 break;
 411         } while (1);
 412 }
 413
 414 static void uloop_handle_sigint(int signo)
 415 {
 416         uloop_status = signo;
 417         uloop_cancelled = true;
 418         uloop_signal_wake();
 419 }
 420
 421 static void uloop_sigchld(int signo)
 422 {
 423         do_sigchld = true;
 424         uloop_signal_wake();
 425 }
 426
 427 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
 428 {
 429         struct sigaction s;
 430         struct sigaction *act;
 431
 432         act = NULL;
 433         sigaction(signum, NULL, &s);
 434
 435         if (add) {
 436                 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
 437                         memcpy(old, &s, sizeof(struct sigaction));
 438                         s.sa_handler = handler;
 439                         s.sa_flags = 0;
 440                         act = &s;
 441                 }
 442         }
 443         else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
 444                         act = old;
 445         }
 446
 447         if (act != NULL)
 448                 sigaction(signum, act, NULL);
 449 }
 450
 451 static void uloop_ignore_signal(int signum, bool ignore)
 452 {
 453         struct sigaction s;
 454         void *new_handler = NULL;
 455
 456         sigaction(signum, NULL, &s);
 457
 458         if (ignore) {
 459                 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
 460                         new_handler = SIG_IGN;
 461         } else {
 462                 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
 463                         new_handler = SIG_DFL;
 464         }
 465
 466         if (new_handler) {
 467                 s.sa_handler = new_handler;
 468                 s.sa_flags = 0;
 469                 sigaction(signum, &s, NULL);
 470         }
 471 }
 472
 473 static void uloop_setup_signals(bool add)
 474 {
 475         static struct sigaction old_sigint, old_sigchld, old_sigterm;
 476
 477         uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
 478         uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
 479
 480         if (uloop_handle_sigchld)
 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         int64_t 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 bool uloop_cancelling(void)
 535 {
 536         return uloop_run_depth > 0 && uloop_cancelled;
 537 }
 538
 539 int uloop_run_timeout(int timeout)
 540 {
 541         int next_time = 0;
 542         struct timeval tv;
 543
 544         uloop_run_depth++;
 545
 546         uloop_status = 0;
 547         uloop_cancelled = false;
 548         while (!uloop_cancelled)
 549         {
 550                 uloop_gettime(&tv);
 551                 uloop_process_timeouts(&tv);
 552
 553                 if (do_sigchld)
 554                         uloop_handle_processes();
 555
 556                 if (uloop_cancelled)
 557                         break;
 558
 559                 uloop_gettime(&tv);
 560
 561                 next_time = uloop_get_next_timeout(&tv);
 562                 if (timeout >= 0 && timeout < next_time)
 563                         next_time = timeout;
 564                 uloop_run_events(next_time);
 565         }
 566
 567         --uloop_run_depth;
 568
 569         return uloop_status;
 570 }
 571
 572 void uloop_done(void)
 573 {
 574         uloop_setup_signals(false);
 575
 576         if (poll_fd >= 0) {
 577                 close(poll_fd);
 578                 poll_fd = -1;
 579         }
 580
 581         if (waker_pipe >= 0) {
 582                 uloop_fd_delete(&waker_fd);
 583                 close(waker_pipe);
 584                 close(waker_fd.fd);
 585                 waker_pipe = -1;
 586         }
 587
 588         uloop_clear_timeouts();
 589         uloop_clear_processes();
 590 }