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