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