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