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