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[disorder] / lib / event.c
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460b9539 1/*
2 * This file is part of DisOrder.
e8c92ba7 3 * Copyright (C) 2004, 2005, 2007 Richard Kettlewell
460b9539 4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
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20/** @file lib/event.c
21 * @brief DisOrder event loop
22 */
460b9539 23
24#include <config.h>
25
26#include <unistd.h>
27#include <fcntl.h>
28#include <sys/time.h>
29#include <sys/types.h>
30#include <sys/resource.h>
31#include <sys/wait.h>
46bd8db4 32#include <sys/stat.h>
460b9539 33#include <unistd.h>
34#include <assert.h>
35#include <signal.h>
36#include <errno.h>
37#include <string.h>
38#include <limits.h>
39#include <sys/socket.h>
40#include <netinet/in.h>
41#include <sys/un.h>
42#include <stdio.h>
43#include "event.h"
44#include "mem.h"
45#include "log.h"
46#include "syscalls.h"
47#include "printf.h"
48#include "sink.h"
768d7355 49#include "vector.h"
460b9539 50
768d7355 51/** @brief A timeout */
460b9539 52struct timeout {
53 struct timeout *next;
54 struct timeval when;
55 ev_timeout_callback *callback;
56 void *u;
57 int resolve;
58};
59
768d7355 60/** @brief A file descriptor in one mode */
460b9539 61struct fd {
62 int fd;
63 ev_fd_callback *callback;
64 void *u;
e8c92ba7 65 const char *what;
460b9539 66};
67
768d7355 68/** @brief All the file descriptors in a given mode */
460b9539 69struct fdmode {
768d7355 70 /** @brief Mask of active file descriptors passed to @c select() */
460b9539 71 fd_set enabled;
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72
73 /** @brief File descriptor mask returned from @c select() */
460b9539 74 fd_set tripped;
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75
76 /** @brief Number of file descriptors in @p fds */
77 int nfds;
78
79 /** @brief Number of slots in @p fds */
80 int fdslots;
81
82 /** @brief Array of all active file descriptors */
460b9539 83 struct fd *fds;
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84
85 /** @brief Highest-numbered file descriptor or 0 */
460b9539 86 int maxfd;
87};
88
768d7355 89/** @brief A signal handler */
460b9539 90struct signal {
91 struct sigaction oldsa;
92 ev_signal_callback *callback;
93 void *u;
94};
95
768d7355 96/** @brief A child process */
460b9539 97struct child {
98 pid_t pid;
99 int options;
100 ev_child_callback *callback;
101 void *u;
102};
103
768d7355 104/** @brief An event loop */
460b9539 105struct ev_source {
768d7355 106 /** @brief File descriptors, per mode */
460b9539 107 struct fdmode mode[ev_nmodes];
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108
109 /** @brief Sorted linked list of timeouts
110 *
111 * We could use @ref HEAP_TYPE now, but there aren't many timeouts.
112 */
460b9539 113 struct timeout *timeouts;
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114
115 /** @brief Array of handled signals */
460b9539 116 struct signal signals[NSIG];
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117
118 /** @brief Mask of handled signals */
460b9539 119 sigset_t sigmask;
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120
121 /** @brief Escape early from handling of @c select() results
122 *
123 * This is set if any of the file descriptor arrays are invalidated, since
124 * it's then not safe for processing of them to continue.
125 */
460b9539 126 int escape;
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127
128 /** @brief Signal handling pipe
129 *
130 * The signal handle writes signal numbers down this pipe.
131 */
460b9539 132 int sigpipe[2];
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133
134 /** @brief Number of child processes in @p children */
135 int nchildren;
136
137 /** @brief Number of slots in @p children */
138 int nchildslots;
139
140 /** @brief Array of child processes */
460b9539 141 struct child *children;
142};
143
768d7355 144/** @brief Names of file descriptor modes */
460b9539 145static const char *modenames[] = { "read", "write", "except" };
146
147/* utilities ******************************************************************/
148
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149/** @brief Great-than comparison for timevals
150 *
151 * Ought to be in @file lib/timeval.h
152 */
460b9539 153static inline int gt(const struct timeval *a, const struct timeval *b) {
154 if(a->tv_sec > b->tv_sec)
155 return 1;
156 if(a->tv_sec == b->tv_sec
157 && a->tv_usec > b->tv_usec)
158 return 1;
159 return 0;
160}
161
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162/** @brief Greater-than-or-equal comparison for timevals
163 *
3149c1e2 164 * Ought to be in @ref lib/timeval.h
768d7355 165 */
460b9539 166static inline int ge(const struct timeval *a, const struct timeval *b) {
167 return !gt(b, a);
168}
169
170/* creation *******************************************************************/
171
768d7355 172/** @brief Create a new event loop */
460b9539 173ev_source *ev_new(void) {
174 ev_source *ev = xmalloc(sizeof *ev);
175 int n;
176
177 memset(ev, 0, sizeof *ev);
178 for(n = 0; n < ev_nmodes; ++n)
179 FD_ZERO(&ev->mode[n].enabled);
180 ev->sigpipe[0] = ev->sigpipe[1] = -1;
181 sigemptyset(&ev->sigmask);
182 return ev;
183}
184
185/* event loop *****************************************************************/
186
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187/** @brief Run the event loop
188 * @return -1 on error, non-0 if any callback returned non-0
189 */
460b9539 190int ev_run(ev_source *ev) {
191 for(;;) {
192 struct timeval now;
193 struct timeval delta;
194 int n, mode;
195 int ret;
196 int maxfd;
197 struct timeout *t, **tt;
e8c92ba7 198 struct stat sb;
460b9539 199
200 xgettimeofday(&now, 0);
201 /* Handle timeouts. We don't want to handle any timeouts that are added
202 * while we're handling them (otherwise we'd have to break out of infinite
203 * loops, preferrably without starving better-behaved subsystems). Hence
204 * the slightly complicated two-phase approach here. */
205 for(t = ev->timeouts;
206 t && ge(&now, &t->when);
207 t = t->next) {
208 t->resolve = 1;
209 D(("calling timeout for %ld.%ld callback %p %p",
210 (long)t->when.tv_sec, (long)t->when.tv_usec,
211 (void *)t->callback, t->u));
212 ret = t->callback(ev, &now, t->u);
213 if(ret)
214 return ret;
215 }
216 tt = &ev->timeouts;
217 while((t = *tt)) {
218 if(t->resolve)
219 *tt = t->next;
220 else
221 tt = &t->next;
222 }
223 maxfd = 0;
224 for(mode = 0; mode < ev_nmodes; ++mode) {
225 ev->mode[mode].tripped = ev->mode[mode].enabled;
226 if(ev->mode[mode].maxfd > maxfd)
227 maxfd = ev->mode[mode].maxfd;
228 }
229 xsigprocmask(SIG_UNBLOCK, &ev->sigmask, 0);
230 do {
231 if(ev->timeouts) {
232 xgettimeofday(&now, 0);
233 delta.tv_sec = ev->timeouts->when.tv_sec - now.tv_sec;
234 delta.tv_usec = ev->timeouts->when.tv_usec - now.tv_usec;
235 if(delta.tv_usec < 0) {
236 delta.tv_usec += 1000000;
237 --delta.tv_sec;
238 }
239 if(delta.tv_sec < 0)
240 delta.tv_sec = delta.tv_usec = 0;
241 n = select(maxfd + 1,
242 &ev->mode[ev_read].tripped,
243 &ev->mode[ev_write].tripped,
244 &ev->mode[ev_except].tripped,
245 &delta);
246 } else {
247 n = select(maxfd + 1,
248 &ev->mode[ev_read].tripped,
249 &ev->mode[ev_write].tripped,
250 &ev->mode[ev_except].tripped,
251 0);
252 }
253 } while(n < 0 && errno == EINTR);
254 xsigprocmask(SIG_BLOCK, &ev->sigmask, 0);
255 if(n < 0) {
256 error(errno, "error calling select");
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257 if(errno == EBADF) {
258 /* If there's a bad FD in the mix then check them all and log what we
259 * find, to ease debugging */
260 for(mode = 0; mode < ev_nmodes; ++mode) {
261 for(n = 0; n < ev->mode[mode].nfds; ++n) {
262 const int fd = ev->mode[mode].fds[n].fd;
263
264 if(FD_ISSET(fd, &ev->mode[mode].enabled)
265 && fstat(fd, &sb) < 0)
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266 error(errno, "mode %s fstat %d (%s)",
267 modenames[mode], fd, ev->mode[mode].fds[n].what);
e8c92ba7 268 }
7958ad2f 269 for(n = 0; n <= maxfd; ++n)
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270 if(FD_ISSET(n, &ev->mode[mode].enabled)
271 && fstat(n, &sb) < 0)
272 error(errno, "mode %s fstat %d", modenames[mode], n);
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273 }
274 }
460b9539 275 return -1;
276 }
277 if(n > 0) {
278 /* if anything deranges the meaning of an fd, or re-orders the
279 * fds[] tables, we'd better give up; such operations will
280 * therefore set @escape@. */
281 ev->escape = 0;
282 for(mode = 0; mode < ev_nmodes && !ev->escape; ++mode)
283 for(n = 0; n < ev->mode[mode].nfds && !ev->escape; ++n) {
284 int fd = ev->mode[mode].fds[n].fd;
285 if(FD_ISSET(fd, &ev->mode[mode].tripped)) {
286 D(("calling %s fd %d callback %p %p", modenames[mode], fd,
287 (void *)ev->mode[mode].fds[n].callback,
288 ev->mode[mode].fds[n].u));
289 ret = ev->mode[mode].fds[n].callback(ev, fd,
290 ev->mode[mode].fds[n].u);
291 if(ret)
292 return ret;
293 }
294 }
295 }
296 /* we'll pick up timeouts back round the loop */
297 }
298}
299
300/* file descriptors ***********************************************************/
301
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302/** @brief Register a file descriptor
303 * @param ev Event loop
304 * @param mode @c ev_read or @c ev_write
305 * @param fd File descriptor
306 * @param callback Called when @p is readable/writable
307 * @param u Passed to @p callback
308 * @param what Text description
309 * @return 0 on success, non-0 on error
310 *
311 * Sets @ref ev_source::escape, so no further processing of file descriptors
312 * will occur this time round the event loop.
313 */
460b9539 314int ev_fd(ev_source *ev,
315 ev_fdmode mode,
316 int fd,
317 ev_fd_callback *callback,
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318 void *u,
319 const char *what) {
460b9539 320 int n;
321
322 D(("registering %s fd %d callback %p %p", modenames[mode], fd,
323 (void *)callback, u));
324 assert(mode < ev_nmodes);
325 if(ev->mode[mode].nfds >= ev->mode[mode].fdslots) {
326 ev->mode[mode].fdslots = (ev->mode[mode].fdslots
327 ? 2 * ev->mode[mode].fdslots : 16);
328 D(("expanding %s fd table to %d entries", modenames[mode],
329 ev->mode[mode].fdslots));
330 ev->mode[mode].fds = xrealloc(ev->mode[mode].fds,
331 ev->mode[mode].fdslots * sizeof (struct fd));
332 }
333 n = ev->mode[mode].nfds++;
334 FD_SET(fd, &ev->mode[mode].enabled);
335 ev->mode[mode].fds[n].fd = fd;
336 ev->mode[mode].fds[n].callback = callback;
337 ev->mode[mode].fds[n].u = u;
e8c92ba7 338 ev->mode[mode].fds[n].what = what;
460b9539 339 if(fd > ev->mode[mode].maxfd)
340 ev->mode[mode].maxfd = fd;
341 ev->escape = 1;
342 return 0;
343}
344
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345/** @brief Cancel a file descriptor
346 * @param ev Event loop
347 * @param mode @c ev_read or @c ev_write
348 * @param fd File descriptor
349 * @return 0 on success, non-0 on error
350 *
351 * Sets @ref ev_source::escape, so no further processing of file descriptors
352 * will occur this time round the event loop.
353 */
460b9539 354int ev_fd_cancel(ev_source *ev, ev_fdmode mode, int fd) {
355 int n;
356 int maxfd;
357
358 D(("cancelling mode %s fd %d", modenames[mode], fd));
359 /* find the right struct fd */
360 for(n = 0; n < ev->mode[mode].nfds && fd != ev->mode[mode].fds[n].fd; ++n)
361 ;
362 assert(n < ev->mode[mode].nfds);
363 /* swap in the last fd and reduce the count */
364 if(n != ev->mode[mode].nfds - 1)
365 ev->mode[mode].fds[n] = ev->mode[mode].fds[ev->mode[mode].nfds - 1];
366 --ev->mode[mode].nfds;
367 /* if that was the biggest fd, find the new biggest one */
368 if(fd == ev->mode[mode].maxfd) {
369 maxfd = 0;
370 for(n = 0; n < ev->mode[mode].nfds; ++n)
371 if(ev->mode[mode].fds[n].fd > maxfd)
372 maxfd = ev->mode[mode].fds[n].fd;
373 ev->mode[mode].maxfd = maxfd;
374 }
375 /* don't tell select about this fd any more */
376 FD_CLR(fd, &ev->mode[mode].enabled);
377 ev->escape = 1;
378 return 0;
379}
380
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381/** @brief Re-enable a file descriptor
382 * @param ev Event loop
383 * @param mode @c ev_read or @c ev_write
384 * @param fd File descriptor
385 * @return 0 on success, non-0 on error
386 *
387 * It is harmless if @p fd is currently disabled, but it must not have been
388 * cancelled.
389 */
460b9539 390int ev_fd_enable(ev_source *ev, ev_fdmode mode, int fd) {
38b8221f 391 assert(fd >= 0);
460b9539 392 D(("enabling mode %s fd %d", modenames[mode], fd));
393 FD_SET(fd, &ev->mode[mode].enabled);
394 return 0;
395}
396
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397/** @brief Temporarily disable a file descriptor
398 * @param ev Event loop
399 * @param mode @c ev_read or @c ev_write
400 * @param fd File descriptor
401 * @return 0 on success, non-0 on error
402 *
403 * Re-enable with ev_fd_enable(). It is harmless if @p fd is already disabled,
404 * but it must not have been cancelled.
405 */
460b9539 406int ev_fd_disable(ev_source *ev, ev_fdmode mode, int fd) {
407 D(("disabling mode %s fd %d", modenames[mode], fd));
408 FD_CLR(fd, &ev->mode[mode].enabled);
409 FD_CLR(fd, &ev->mode[mode].tripped);
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410 /* Suppress any pending callbacks */
411 ev->escape = 1;
460b9539 412 return 0;
413}
414
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415/** @brief Log a report of file descriptor state */
416void ev_report(ev_source *ev) {
417 int n, fd;
418 ev_fdmode mode;
419 struct dynstr d[1];
420 char b[4096];
421
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422 if(!debugging)
423 return;
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424 dynstr_init(d);
425 for(mode = 0; mode < ev_nmodes; ++mode) {
0fa83caa 426 D(("mode %s maxfd %d", modenames[mode], ev->mode[mode].maxfd));
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427 for(n = 0; n < ev->mode[mode].nfds; ++n) {
428 fd = ev->mode[mode].fds[n].fd;
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429 D(("fd %s %d%s%s (%s)", modenames[mode], fd,
430 FD_ISSET(fd, &ev->mode[mode].enabled) ? " enabled" : "",
431 FD_ISSET(fd, &ev->mode[mode].tripped) ? " tripped" : "",
432 ev->mode[mode].fds[n].what));
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433 }
434 d->nvec = 0;
435 for(fd = 0; fd <= ev->mode[mode].maxfd; ++fd) {
436 if(!FD_ISSET(fd, &ev->mode[mode].enabled))
437 continue;
438 for(n = 0; n < ev->mode[mode].nfds; ++n) {
439 if(ev->mode[mode].fds[n].fd == fd)
440 break;
441 }
442 if(n < ev->mode[mode].nfds)
34a3e246 443 snprintf(b, sizeof b, "%d(%s)", fd, ev->mode[mode].fds[n].what);
768d7355 444 else
34a3e246 445 snprintf(b, sizeof b, "%d", fd);
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446 dynstr_append(d, ' ');
447 dynstr_append_string(d, b);
448 }
449 dynstr_terminate(d);
0fa83caa 450 D(("%s enabled:%s", modenames[mode], d->vec));
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451 }
452}
453
460b9539 454/* timeouts *******************************************************************/
455
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456/** @brief Register a timeout
457 * @param ev Event source
3149c1e2 458 * @param handlep Where to store timeout handle, or @c NULL
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459 * @param when Earliest time to call @p callback, or @c NULL
460 * @param callback Function to call at or after @p when
461 * @param u Passed to @p callback
462 * @return 0 on success, non-0 on error
463 *
464 * If @p when is a null pointer then a time of 0 is assumed. The effect is to
465 * call the timeout handler from ev_run() next time around the event loop.
466 * This is used internally to schedule various operations if it is not
467 * convenient to call them from the current place in the call stack, or
468 * externally to ensure that other clients of the event loop get a look in when
469 * performing some lengthy operation.
470 */
460b9539 471int ev_timeout(ev_source *ev,
472 ev_timeout_handle *handlep,
473 const struct timeval *when,
474 ev_timeout_callback *callback,
475 void *u) {
476 struct timeout *t, *p, **pp;
477
478 D(("registering timeout at %ld.%ld callback %p %p",
479 when ? (long)when->tv_sec : 0, when ? (long)when->tv_usec : 0,
480 (void *)callback, u));
481 t = xmalloc(sizeof *t);
482 if(when)
483 t->when = *when;
484 t->callback = callback;
485 t->u = u;
486 pp = &ev->timeouts;
487 while((p = *pp) && gt(&t->when, &p->when))
488 pp = &p->next;
489 t->next = p;
490 *pp = t;
491 if(handlep)
492 *handlep = t;
493 return 0;
494}
495
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496/** @brief Cancel a timeout
497 * @param ev Event loop
cb9a695c 498 * @param handle Handle returned from ev_timeout(), or 0
768d7355 499 * @return 0 on success, non-0 on error
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500 *
501 * If @p handle is 0 then this is a no-op.
768d7355 502 */
460b9539 503int ev_timeout_cancel(ev_source *ev,
504 ev_timeout_handle handle) {
505 struct timeout *t = handle, *p, **pp;
506
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507 if(!t)
508 return 0;
460b9539 509 for(pp = &ev->timeouts; (p = *pp) && p != t; pp = &p->next)
510 ;
511 if(p) {
512 *pp = p->next;
513 return 0;
514 } else
515 return -1;
516}
517
518/* signals ********************************************************************/
519
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520/** @brief Mapping of signals to pipe write ends
521 *
522 * The pipes are per-event loop, it's possible in theory for there to be
523 * multiple event loops (e.g. in different threads), although in fact DisOrder
524 * does not do this.
525 */
460b9539 526static int sigfd[NSIG];
527
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528/** @brief The signal handler
529 * @param s Signal number
530 *
531 * Writes to @c sigfd[s].
532 */
460b9539 533static void sighandler(int s) {
534 unsigned char sc = s;
535 static const char errmsg[] = "error writing to signal pipe";
536
537 /* probably the reader has stopped listening for some reason */
538 if(write(sigfd[s], &sc, 1) < 0) {
539 write(2, errmsg, sizeof errmsg - 1);
540 abort();
541 }
542}
543
768d7355 544/** @brief Read callback for signals */
460b9539 545static int signal_read(ev_source *ev,
546 int attribute((unused)) fd,
547 void attribute((unused)) *u) {
548 unsigned char s;
549 int n;
550 int ret;
551
552 if((n = read(ev->sigpipe[0], &s, 1)) == 1)
553 if((ret = ev->signals[s].callback(ev, s, ev->signals[s].u)))
554 return ret;
555 assert(n != 0);
556 if(n < 0 && (errno != EINTR && errno != EAGAIN)) {
557 error(errno, "error reading from signal pipe %d", ev->sigpipe[0]);
558 return -1;
559 }
560 return 0;
561}
562
768d7355 563/** @brief Close the signal pipe */
460b9539 564static void close_sigpipe(ev_source *ev) {
565 int save_errno = errno;
566
567 xclose(ev->sigpipe[0]);
568 xclose(ev->sigpipe[1]);
569 ev->sigpipe[0] = ev->sigpipe[1] = -1;
570 errno = save_errno;
571}
572
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573/** @brief Register a signal handler
574 * @param ev Event loop
575 * @param sig Signal to handle
576 * @param callback Called when signal is delivered
577 * @param u Passed to @p callback
578 * @return 0 on success, non-0 on error
579 *
580 * Note that @p callback is called from inside ev_run(), not from inside the
581 * signal handler, so the usual restrictions on signal handlers do not apply.
582 */
460b9539 583int ev_signal(ev_source *ev,
584 int sig,
585 ev_signal_callback *callback,
586 void *u) {
587 int n;
588 struct sigaction sa;
589
590 D(("registering signal %d handler callback %p %p", sig, (void *)callback, u));
591 assert(sig > 0);
592 assert(sig < NSIG);
593 assert(sig <= UCHAR_MAX);
594 if(ev->sigpipe[0] == -1) {
595 D(("creating signal pipe"));
596 xpipe(ev->sigpipe);
597 D(("signal pipe is %d, %d", ev->sigpipe[0], ev->sigpipe[1]));
598 for(n = 0; n < 2; ++n) {
599 nonblock(ev->sigpipe[n]);
600 cloexec(ev->sigpipe[n]);
601 }
e8c92ba7 602 if(ev_fd(ev, ev_read, ev->sigpipe[0], signal_read, 0, "sigpipe read")) {
460b9539 603 close_sigpipe(ev);
604 return -1;
605 }
606 }
607 sigaddset(&ev->sigmask, sig);
608 xsigprocmask(SIG_BLOCK, &ev->sigmask, 0);
609 sigfd[sig] = ev->sigpipe[1];
610 ev->signals[sig].callback = callback;
611 ev->signals[sig].u = u;
612 sa.sa_handler = sighandler;
613 sigfillset(&sa.sa_mask);
614 sa.sa_flags = SA_RESTART;
615 xsigaction(sig, &sa, &ev->signals[sig].oldsa);
616 ev->escape = 1;
617 return 0;
618}
619
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620/** @brief Cancel a signal handler
621 * @param ev Event loop
622 * @param sig Signal to cancel
623 * @return 0 on success, non-0 on error
624 */
460b9539 625int ev_signal_cancel(ev_source *ev,
626 int sig) {
627 sigset_t ss;
628
629 xsigaction(sig, &ev->signals[sig].oldsa, 0);
630 ev->signals[sig].callback = 0;
631 ev->escape = 1;
632 sigdelset(&ev->sigmask, sig);
633 sigemptyset(&ss);
634 sigaddset(&ss, sig);
635 xsigprocmask(SIG_UNBLOCK, &ss, 0);
636 return 0;
637}
638
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639/** @brief Clean up signal handling
640 * @param ev Event loop
641 *
642 * This function can be called from inside a fork. It restores signal
643 * handlers, unblocks the signals, and closes the signal pipe for @p ev.
644 */
460b9539 645void ev_signal_atfork(ev_source *ev) {
646 int sig;
647
648 if(ev->sigpipe[0] != -1) {
649 /* revert any handled signals to their original state */
650 for(sig = 1; sig < NSIG; ++sig) {
651 if(ev->signals[sig].callback != 0)
652 xsigaction(sig, &ev->signals[sig].oldsa, 0);
653 }
654 /* and then unblock them */
655 xsigprocmask(SIG_UNBLOCK, &ev->sigmask, 0);
656 /* don't want a copy of the signal pipe open inside the fork */
657 xclose(ev->sigpipe[0]);
658 xclose(ev->sigpipe[1]);
659 }
660}
661
662/* child processes ************************************************************/
663
768d7355 664/** @brief Called on SIGCHLD */
460b9539 665static int sigchld_callback(ev_source *ev,
666 int attribute((unused)) sig,
667 void attribute((unused)) *u) {
668 struct rusage ru;
669 pid_t r;
670 int status, n, ret, revisit;
671
672 do {
673 revisit = 0;
674 for(n = 0; n < ev->nchildren; ++n) {
675 r = wait4(ev->children[n].pid,
676 &status,
677 ev->children[n].options | WNOHANG,
678 &ru);
679 if(r > 0) {
680 ev_child_callback *c = ev->children[n].callback;
681 void *cu = ev->children[n].u;
682
683 if(WIFEXITED(status) || WIFSIGNALED(status))
684 ev_child_cancel(ev, r);
685 revisit = 1;
686 if((ret = c(ev, r, status, &ru, cu)))
687 return ret;
688 } else if(r < 0) {
689 /* We should "never" get an ECHILD but it can in fact happen. For
690 * instance on Linux 2.4.31, and probably other versions, if someone
691 * straces a child process and then a different child process
692 * terminates, when we wait4() the trace process we will get ECHILD
693 * because it has been reparented to strace. Obviously this is a
694 * hopeless design flaw in the tracing infrastructure, but we don't
695 * want the disorder server to bomb out because of it. So we just log
696 * the problem and ignore it.
697 */
698 error(errno, "error calling wait4 for PID %lu (broken ptrace?)",
699 (unsigned long)ev->children[n].pid);
700 if(errno != ECHILD)
701 return -1;
702 }
703 }
704 } while(revisit);
705 return 0;
706}
707
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708/** @brief Configure event loop for child process handling
709 * @return 0 on success, non-0 on error
710 *
711 * Currently at most one event loop can handle child processes and it must be
712 * distinguished from others by calling this function on it. This could be
713 * fixed but since no process ever makes use of more than one event loop there
714 * is no need.
715 */
460b9539 716int ev_child_setup(ev_source *ev) {
717 D(("installing SIGCHLD handler"));
718 return ev_signal(ev, SIGCHLD, sigchld_callback, 0);
719}
720
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721/** @brief Wait for a child process to terminate
722 * @param ev Event loop
723 * @param pid Process ID of child
724 * @param options Options to pass to @c wait4()
725 * @param callback Called when child terminates (or possibly when it stops)
726 * @param u Passed to @p callback
727 * @return 0 on success, non-0 on error
728 *
729 * You must have called ev_child_setup() on @p ev once first.
730 */
460b9539 731int ev_child(ev_source *ev,
732 pid_t pid,
733 int options,
734 ev_child_callback *callback,
735 void *u) {
736 int n;
737
738 D(("registering child handling %ld options %d callback %p %p",
739 (long)pid, options, (void *)callback, u));
740 assert(ev->signals[SIGCHLD].callback == sigchld_callback);
741 if(ev->nchildren >= ev->nchildslots) {
742 ev->nchildslots = ev->nchildslots ? 2 * ev->nchildslots : 16;
743 ev->children = xrealloc(ev->children,
744 ev->nchildslots * sizeof (struct child));
745 }
746 n = ev->nchildren++;
747 ev->children[n].pid = pid;
748 ev->children[n].options = options;
749 ev->children[n].callback = callback;
750 ev->children[n].u = u;
751 return 0;
752}
753
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754/** @brief Stop waiting for a child process
755 * @param ev Event loop
756 * @param pid Child process ID
757 * @return 0 on success, non-0 on error
758 */
460b9539 759int ev_child_cancel(ev_source *ev,
760 pid_t pid) {
761 int n;
762
763 for(n = 0; n < ev->nchildren && ev->children[n].pid != pid; ++n)
764 ;
765 assert(n < ev->nchildren);
766 if(n != ev->nchildren - 1)
767 ev->children[n] = ev->children[ev->nchildren - 1];
768 --ev->nchildren;
769 return 0;
770}
771
772/* socket listeners ***********************************************************/
773
768d7355 774/** @brief State for a socket listener */
460b9539 775struct listen_state {
776 ev_listen_callback *callback;
777 void *u;
778};
779
768d7355 780/** @brief Called when a listenign socket is readable */
460b9539 781static int listen_callback(ev_source *ev, int fd, void *u) {
782 const struct listen_state *l = u;
783 int newfd;
784 union {
785 struct sockaddr_in in;
786#if HAVE_STRUCT_SOCKADDR_IN6
787 struct sockaddr_in6 in6;
788#endif
789 struct sockaddr_un un;
790 struct sockaddr sa;
791 } addr;
792 socklen_t addrlen;
793 int ret;
794
795 D(("callback for listener fd %d", fd));
796 while((addrlen = sizeof addr),
797 (newfd = accept(fd, &addr.sa, &addrlen)) >= 0) {
798 if((ret = l->callback(ev, newfd, &addr.sa, addrlen, l->u)))
799 return ret;
800 }
801 switch(errno) {
802 case EINTR:
803 case EAGAIN:
804 break;
805#ifdef ECONNABORTED
806 case ECONNABORTED:
807 error(errno, "error calling accept");
808 break;
809#endif
810#ifdef EPROTO
811 case EPROTO:
812 /* XXX on some systems EPROTO should be fatal, but we don't know if
813 * we're running on one of them */
814 error(errno, "error calling accept");
815 break;
816#endif
817 default:
818 fatal(errno, "error calling accept");
819 break;
820 }
821 if(errno != EINTR && errno != EAGAIN)
822 error(errno, "error calling accept");
823 return 0;
824}
825
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826/** @brief Listen on a socket for inbound stream connections
827 * @param ev Event source
828 * @param fd File descriptor of socket
829 * @param callback Called when a new connection arrives
830 * @param u Passed to @p callback
831 * @param what Text description of socket
832 * @return 0 on success, non-0 on error
833 */
460b9539 834int ev_listen(ev_source *ev,
835 int fd,
836 ev_listen_callback *callback,
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837 void *u,
838 const char *what) {
460b9539 839 struct listen_state *l = xmalloc(sizeof *l);
840
841 D(("registering listener fd %d callback %p %p", fd, (void *)callback, u));
842 l->callback = callback;
843 l->u = u;
e8c92ba7 844 return ev_fd(ev, ev_read, fd, listen_callback, l, what);
460b9539 845}
846
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847/** @brief Stop listening on a socket
848 * @param ev Event loop
849 * @param fd File descriptor of socket
850 * @return 0 on success, non-0 on error
851 */
460b9539 852int ev_listen_cancel(ev_source *ev, int fd) {
853 D(("cancelling listener fd %d", fd));
854 return ev_fd_cancel(ev, ev_read, fd);
855}
856
857/* buffer *********************************************************************/
858
768d7355 859/** @brief Buffer structure */
460b9539 860struct buffer {
861 char *base, *start, *end, *top;
862};
863
768d7355 864/* @brief Make sure there is @p bytes available at @c b->end */
460b9539 865static void buffer_space(struct buffer *b, size_t bytes) {
866 D(("buffer_space %p %p %p %p want %lu",
867 (void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top,
868 (unsigned long)bytes));
869 if(b->start == b->end)
870 b->start = b->end = b->base;
871 if((size_t)(b->top - b->end) < bytes) {
872 if((size_t)((b->top - b->end) + (b->start - b->base)) < bytes) {
873 size_t newspace = b->end - b->start + bytes, n;
874 char *newbase;
875
876 for(n = 16; n < newspace; n *= 2)
877 ;
878 newbase = xmalloc_noptr(n);
879 memcpy(newbase, b->start, b->end - b->start);
880 b->base = newbase;
881 b->end = newbase + (b->end - b->start);
882 b->top = newbase + n;
883 b->start = newbase; /* must be last */
884 } else {
885 memmove(b->base, b->start, b->end - b->start);
886 b->end = b->base + (b->end - b->start);
887 b->start = b->base;
888 }
889 }
890 D(("result %p %p %p %p",
891 (void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top));
892}
893
75d64210 894/* readers and writers *******************************************************/
460b9539 895
768d7355 896/** @brief State structure for a buffered writer */
460b9539 897struct ev_writer {
75d64210 898 /** @brief Sink used for writing to the buffer */
460b9539 899 struct sink s;
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900
901 /** @brief Output buffer */
460b9539 902 struct buffer b;
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903
904 /** @brief File descriptor to write to */
460b9539 905 int fd;
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906
907 /** @brief Set if there'll be no more output */
460b9539 908 int eof;
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909
910 /** @brief Error/termination callback */
460b9539 911 ev_error_callback *callback;
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912
913 /** @brief Passed to @p callback */
460b9539 914 void *u;
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915
916 /** @brief Parent event source */
460b9539 917 ev_source *ev;
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918
919 /** @brief Maximum amount of time between succesful writes, 0 = don't care */
920 int timebound;
921 /** @brief Maximum amount of data to buffer, 0 = don't care */
922 int spacebound;
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923 /** @brief Error code to pass to @p callback (see writer_shutdown()) */
924 int error;
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925 /** @brief Timeout handle for @p timebound (or 0) */
926 ev_timeout_handle timeout;
927
75d64210 928 /** @brief Description of this writer */
cb9a695c 929 const char *what;
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930
931 /** @brief Tied reader or 0 */
932 ev_reader *reader;
460b9539 933};
934
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935/** @brief State structure for a buffered reader */
936struct ev_reader {
937 /** @brief Input buffer */
938 struct buffer b;
939 /** @brief File descriptor read from */
940 int fd;
941 /** @brief Called when new data is available */
942 ev_reader_callback *callback;
943 /** @brief Called on error and shutdown */
944 ev_error_callback *error_callback;
945 /** @brief Passed to @p callback and @p error_callback */
946 void *u;
947 /** @brief Parent event loop */
948 ev_source *ev;
949 /** @brief Set when EOF is detected */
950 int eof;
951 /** @brief Error code to pass to error callback */
952 int error;
953 /** @brief Tied writer or NULL */
954 ev_writer *writer;
955};
956
957/* buffered writer ************************************************************/
958
959/** @brief Shut down the writer
960 *
961 * This is called to shut down a writer. The error callback is not called
962 * through any other path. Also we do not cancel @p fd from anywhere else,
963 * though we might disable it.
964 *
965 * It has the signature of a timeout callback so that it can be called from a
966 * time=0 timeout.
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967 *
968 * Calls @p callback with @p w->syntherr as the error code (which might be 0).
969 */
970static int writer_shutdown(ev_source *ev,
971 const attribute((unused)) struct timeval *now,
972 void *u) {
973 ev_writer *w = u;
974
e4a9c7c5 975 if(w->fd == -1)
75d64210 976 return 0; /* already shut down */
0fa83caa 977 D(("writer_shutdown fd=%d error=%d", w->fd, w->error));
cb9a695c 978 ev_timeout_cancel(ev, w->timeout);
75d64210 979 ev_fd_cancel(ev, ev_write, w->fd);
cb9a695c 980 w->timeout = 0;
75d64210 981 if(w->reader) {
0fa83caa 982 D(("found a tied reader"));
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983 /* If there is a reader still around we just untie it */
984 w->reader->writer = 0;
985 shutdown(w->fd, SHUT_WR); /* there'll be no more writes */
986 } else {
0fa83caa 987 D(("no tied reader"));
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988 /* There's no reader so we are free to close the FD */
989 xclose(w->fd);
990 }
e4a9c7c5 991 w->fd = -1;
75d64210 992 return w->callback(ev, w->error, w->u);
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993}
994
995/** @brief Called when a writer's @p timebound expires */
996static int writer_timebound_exceeded(ev_source *ev,
75d64210 997 const struct timeval *now,
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998 void *u) {
999 ev_writer *const w = u;
1000
1001 error(0, "abandoning writer %s because no writes within %ds",
1002 w->what, w->timebound);
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1003 w->error = ETIMEDOUT;
1004 return writer_shutdown(ev, now, u);
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1005}
1006
1007/** @brief Set the time bound callback (if not set already) */
1008static void writer_set_timebound(ev_writer *w) {
1009 if(w->timebound && !w->timeout) {
1010 struct timeval when;
1011 ev_source *const ev = w->ev;
1012
1013 xgettimeofday(&when, 0);
1014 when.tv_sec += w->timebound;
1015 ev_timeout(ev, &w->timeout, &when, writer_timebound_exceeded, w);
1016 }
1017}
1018
768d7355 1019/** @brief Called when a writer's file descriptor is writable */
460b9539 1020static int writer_callback(ev_source *ev, int fd, void *u) {
cb9a695c 1021 ev_writer *const w = u;
460b9539 1022 int n;
1023
1024 n = write(fd, w->b.start, w->b.end - w->b.start);
1025 D(("callback for writer fd %d, %ld bytes, n=%d, errno=%d",
1026 fd, (long)(w->b.end - w->b.start), n, errno));
1027 if(n >= 0) {
75d64210 1028 /* Consume bytes from the buffer */
460b9539 1029 w->b.start += n;
75d64210 1030 /* Suppress any outstanding timeout */
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1031 ev_timeout_cancel(ev, w->timeout);
1032 w->timeout = 0;
460b9539 1033 if(w->b.start == w->b.end) {
75d64210 1034 /* The buffer is empty */
460b9539 1035 if(w->eof) {
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1036 /* We're done, we can shut down this writer */
1037 w->error = 0;
1038 return writer_shutdown(ev, 0, w);
460b9539 1039 } else
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1040 /* There might be more to come but we don't need writer_callback() to
1041 * be called for the time being */
460b9539 1042 ev_fd_disable(ev, ev_write, fd);
cb9a695c 1043 } else
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1044 /* The buffer isn't empty, set a timeout so we give up if we don't manage
1045 * to write some more within a reasonable time */
cb9a695c 1046 writer_set_timebound(w);
460b9539 1047 } else {
1048 switch(errno) {
1049 case EINTR:
1050 case EAGAIN:
1051 break;
1052 default:
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1053 w->error = errno;
1054 return writer_shutdown(ev, 0, w);
460b9539 1055 }
1056 }
1057 return 0;
1058}
1059
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1060/** @brief Write bytes to a writer's buffer
1061 *
1062 * This is the sink write callback.
1063 *
1064 * Calls ev_fd_enable() if necessary (i.e. if the buffer was empty but
1065 * now is not).
1066 */
460b9539 1067static int ev_writer_write(struct sink *sk, const void *s, int n) {
1068 ev_writer *w = (ev_writer *)sk;
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1069
1070 if(!n)
1071 return 0; /* avoid silliness */
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1072 if(w->fd == -1)
1073 error(0, "ev_writer_write on %s after shutdown", w->what);
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1074 if(w->spacebound && w->b.end - w->b.start + n > w->spacebound) {
1075 /* The new buffer contents will exceed the space bound. We assume that the
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1076 * remote client has gone away and TCP hasn't noticed yet, or that it's got
1077 * hopelessly stuck. */
1078 error(0, "abandoning writer %s because buffer has reached %td bytes",
1079 w->what, w->b.end - w->b.start);
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1080 ev_fd_disable(w->ev, ev_write, w->fd);
1081 w->error = EPIPE;
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1082 return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
1083 }
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1084 /* Make sure there is space */
1085 buffer_space(&w->b, n);
1086 /* If the buffer was formerly empty then we'll need to re-enable the FD */
1087 if(w->b.start == w->b.end)
1088 ev_fd_enable(w->ev, ev_write, w->fd);
1089 memcpy(w->b.end, s, n);
1090 w->b.end += n;
1091 /* Arrange a timeout if there wasn't one set already */
cb9a695c 1092 writer_set_timebound(w);
460b9539 1093 return 0;
1094}
1095
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1096/** @brief Create a new buffered writer
1097 * @param ev Event loop
1098 * @param fd File descriptor to write to
1099 * @param callback Called if an error occurs and when finished
1100 * @param u Passed to @p callback
1101 * @param what Text description
1102 * @return New writer or @c NULL
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1103 *
1104 * Writers own their file descriptor and close it when they have finished with
1105 * it.
1106 *
1107 * If you pass the same fd to a reader and writer, you must tie them together
1108 * with ev_tie().
768d7355 1109 */
460b9539 1110ev_writer *ev_writer_new(ev_source *ev,
1111 int fd,
1112 ev_error_callback *callback,
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1113 void *u,
1114 const char *what) {
460b9539 1115 ev_writer *w = xmalloc(sizeof *w);
1116
1117 D(("registering writer fd %d callback %p %p", fd, (void *)callback, u));
1118 w->s.write = ev_writer_write;
1119 w->fd = fd;
1120 w->callback = callback;
1121 w->u = u;
1122 w->ev = ev;
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1123 w->timebound = 10 * 60;
1124 w->spacebound = 512 * 1024;
1125 w->what = what;
e8c92ba7 1126 if(ev_fd(ev, ev_write, fd, writer_callback, w, what))
460b9539 1127 return 0;
75d64210 1128 /* Buffer is initially empty so we don't want a callback */
460b9539 1129 ev_fd_disable(ev, ev_write, fd);
1130 return w;
1131}
1132
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1133/** @brief Get/set the time bound
1134 * @param w Writer
1135 * @param new_time_bound New bound or -1 for no change
1136 * @return Latest time bound
1137 *
1138 * If @p new_time_bound is negative then the current time bound is returned.
1139 * Otherwise it is set and the new value returned.
1140 *
1141 * The time bound is the number of seconds allowed between writes. If it takes
1142 * longer than this to flush a buffer then the peer will be assumed to be dead
1143 * and an error will be synthesized. 0 means "don't care". The default time
1144 * bound is 10 minutes.
1145 *
1146 * Note that this value does not take into account kernel buffering and
1147 * timeouts.
1148 */
1149int ev_writer_time_bound(ev_writer *w,
1150 int new_time_bound) {
1151 if(new_time_bound >= 0)
1152 w->timebound = new_time_bound;
1153 return w->timebound;
1154}
1155
1156/** @brief Get/set the space bound
1157 * @param w Writer
1158 * @param new_space_bound New bound or -1 for no change
1159 * @return Latest space bound
1160 *
1161 * If @p new_space_bound is negative then the current space bound is returned.
1162 * Otherwise it is set and the new value returned.
1163 *
1164 * The space bound is the number of bytes allowed between in the buffer. If
1165 * the buffer exceeds this size an error will be synthesized. 0 means "don't
1166 * care". The default space bound is 512Kbyte.
1167 *
1168 * Note that this value does not take into account kernel buffering.
1169 */
1170int ev_writer_space_bound(ev_writer *w,
1171 int new_space_bound) {
1172 if(new_space_bound >= 0)
1173 w->spacebound = new_space_bound;
1174 return w->spacebound;
1175}
1176
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1177/** @brief Return the sink associated with a writer
1178 * @param w Writer
1179 * @return Pointer to sink
1180 *
1181 * Writing to the sink will arrange for those bytes to be written to the file
1182 * descriptor as and when it is writable.
1183 */
460b9539 1184struct sink *ev_writer_sink(ev_writer *w) {
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1185 if(!w)
1186 fatal(0, "ev_write_sink called with null writer");
460b9539 1187 return &w->s;
1188}
1189
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1190/** @brief Close a writer
1191 * @param w Writer to close
1192 * @return 0 on success, non-0 on error
1193 *
1194 * Close a writer. No more bytes should be written to its sink.
1195 *
1196 * When the last byte has been written the callback will be called with an
1197 * error code of 0. It is guaranteed that this will NOT happen before
1198 * ev_writer_close() returns (although the file descriptor for the writer might
1199 * be cancelled by the time it returns).
1200 */
460b9539 1201int ev_writer_close(ev_writer *w) {
1202 D(("close writer fd %d", w->fd));
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1203 if(w->eof)
1204 return 0; /* already closed */
460b9539 1205 w->eof = 1;
1206 if(w->b.start == w->b.end) {
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1207 /* We're already finished */
1208 w->error = 0; /* no error */
460b9539 1209 return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
1210 }
1211 return 0;
1212}
1213
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1214/** @brief Attempt to flush a writer
1215 * @param w Writer to flush
1216 * @return 0 on success, non-0 on error
1217 *
1218 * Does a speculative write of any buffered data. Does not block if it cannot
1219 * be written.
1220 */
460b9539 1221int ev_writer_flush(ev_writer *w) {
1222 return writer_callback(w->ev, w->fd, w);
1223}
1224
1225/* buffered reader ************************************************************/
1226
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1227/** @brief Shut down a reader*
1228 *
1229 * This is the only path through which we cancel and close the file descriptor.
1230 * As with the writer case it is given timeout signature to allow it be
1231 * deferred to the next iteration of the event loop.
1232 *
1233 * We only call @p error_callback if @p error is nonzero (unlike the writer
1234 * case).
1235 */
1236static int reader_shutdown(ev_source *ev,
1237 const attribute((unused)) struct timeval *now,
1238 void *u) {
1239 ev_reader *const r = u;
1240
1241 if(r->fd == -1)
1242 return 0; /* already shut down */
0fa83caa 1243 D(("reader_shutdown fd=%d", r->fd));
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1244 ev_fd_cancel(ev, ev_read, r->fd);
1245 r->eof = 1;
1246 if(r->writer) {
0fa83caa 1247 D(("found a tied writer"));
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1248 /* If there is a writer still around we just untie it */
1249 r->writer->reader = 0;
1250 shutdown(r->fd, SHUT_RD); /* there'll be no more reads */
1251 } else {
0fa83caa 1252 D(("no tied writer found"));
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1253 /* There's no writer so we are free to close the FD */
1254 xclose(r->fd);
1255 }
1256 r->fd = -1;
1257 if(r->error)
1258 return r->error_callback(ev, r->error, r->u);
1259 else
1260 return 0;
1261}
460b9539 1262
768d7355 1263/** @brief Called when a reader's @p fd is readable */
460b9539 1264static int reader_callback(ev_source *ev, int fd, void *u) {
1265 ev_reader *r = u;
1266 int n;
1267
1268 buffer_space(&r->b, 1);
1269 n = read(fd, r->b.end, r->b.top - r->b.end);
1270 D(("read fd %d buffer %d returned %d errno %d",
1271 fd, (int)(r->b.top - r->b.end), n, errno));
1272 if(n > 0) {
1273 r->b.end += n;
75d64210 1274 return r->callback(ev, r, r->b.start, r->b.end - r->b.start, 0, r->u);
460b9539 1275 } else if(n == 0) {
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1276 /* No more read callbacks needed */
1277 ev_fd_disable(r->ev, ev_read, r->fd);
1278 ev_timeout(r->ev, 0, 0, reader_shutdown, r);
1279 /* Pass the remaining data and an eof indicator to the user */
1280 return r->callback(ev, r, r->b.start, r->b.end - r->b.start, 1, r->u);
460b9539 1281 } else {
1282 switch(errno) {
1283 case EINTR:
1284 case EAGAIN:
1285 break;
1286 default:
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1287 /* Fatal error, kill the reader now */
1288 r->error = errno;
1289 return reader_shutdown(ev, 0, r);
460b9539 1290 }
1291 }
1292 return 0;
1293}
1294
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1295/** @brief Create a new buffered reader
1296 * @param ev Event loop
1297 * @param fd File descriptor to read from
1298 * @param callback Called when new data is available
1299 * @param error_callback Called if an error occurs
1300 * @param u Passed to callbacks
1301 * @param what Text description
1302 * @return New reader or @c NULL
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1303 *
1304 * Readers own their fd and close it when they are finished with it.
1305 *
1306 * If you pass the same fd to a reader and writer, you must tie them together
1307 * with ev_tie().
768d7355 1308 */
460b9539 1309ev_reader *ev_reader_new(ev_source *ev,
1310 int fd,
1311 ev_reader_callback *callback,
1312 ev_error_callback *error_callback,
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1313 void *u,
1314 const char *what) {
460b9539 1315 ev_reader *r = xmalloc(sizeof *r);
1316
1317 D(("registering reader fd %d callback %p %p %p",
1318 fd, (void *)callback, (void *)error_callback, u));
1319 r->fd = fd;
1320 r->callback = callback;
1321 r->error_callback = error_callback;
1322 r->u = u;
1323 r->ev = ev;
e8c92ba7 1324 if(ev_fd(ev, ev_read, fd, reader_callback, r, what))
460b9539 1325 return 0;
1326 return r;
1327}
1328
1329void ev_reader_buffer(ev_reader *r, size_t nbytes) {
1330 buffer_space(&r->b, nbytes - (r->b.end - r->b.start));
1331}
1332
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1333/** @brief Consume @p n bytes from the reader's buffer
1334 * @param r Reader
1335 * @param n Number of bytes to consume
1336 *
1337 * Tells the reader than the next @p n bytes have been dealt with and can now
1338 * be discarded.
1339 */
460b9539 1340void ev_reader_consume(ev_reader *r, size_t n) {
1341 r->b.start += n;
1342}
1343
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1344/** @brief Cancel a reader
1345 * @param r Reader
1346 * @return 0 on success, non-0 on error
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1347 *
1348 * No further callbacks will be made, and the FD will be closed (in a later
1349 * iteration of the event loop).
768d7355 1350 */
460b9539 1351int ev_reader_cancel(ev_reader *r) {
1352 D(("cancel reader fd %d", r->fd));
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1353 if(r->fd == -1)
1354 return 0; /* already thoroughly cancelled */
1355 ev_fd_disable(r->ev, ev_read, r->fd);
1356 return ev_timeout(r->ev, 0, 0, reader_shutdown, r);
460b9539 1357}
1358
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1359/** @brief Temporarily disable a reader
1360 * @param r Reader
1361 * @return 0 on success, non-0 on error
1362 *
1363 * No further callbacks for this reader will be made. Re-enable with
1364 * ev_reader_enable().
1365 */
460b9539 1366int ev_reader_disable(ev_reader *r) {
1367 D(("disable reader fd %d", r->fd));
75d64210 1368 return ev_fd_disable(r->ev, ev_read, r->fd);
460b9539 1369}
1370
768d7355 1371/** @brief Called from ev_run() for ev_reader_incomplete() */
460b9539 1372static int reader_continuation(ev_source attribute((unused)) *ev,
1373 const attribute((unused)) struct timeval *now,
1374 void *u) {
1375 ev_reader *r = u;
1376
1377 D(("reader continuation callback fd %d", r->fd));
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1378 /* If not at EOF turn the FD back on */
1379 if(!r->eof)
1380 if(ev_fd_enable(r->ev, ev_read, r->fd))
1381 return -1;
1382 /* We're already in a timeout callback so there's no reason we can't call the
1383 * user callback directly (compare ev_reader_enable()). */
1384 return r->callback(ev, r, r->b.start, r->b.end - r->b.start, r->eof, r->u);
460b9539 1385}
1386
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1387/** @brief Arrange another callback
1388 * @param r reader
1389 * @return 0 on success, non-0 on error
1390 *
1391 * Indicates that the reader can process more input but would like to yield to
1392 * other clients of the event loop. Input will be disabled but it will be
1393 * re-enabled on the next iteration of the event loop and the read callback
1394 * will be called again (even if no further bytes are available).
1395 */
460b9539 1396int ev_reader_incomplete(ev_reader *r) {
1397 if(ev_fd_disable(r->ev, ev_read, r->fd)) return -1;
1398 return ev_timeout(r->ev, 0, 0, reader_continuation, r);
1399}
1400
1401static int reader_enabled(ev_source *ev,
1402 const attribute((unused)) struct timeval *now,
1403 void *u) {
1404 ev_reader *r = u;
1405
1406 D(("reader enabled callback fd %d", r->fd));
75d64210 1407 return r->callback(ev, r, r->b.start, r->b.end - r->b.start, r->eof, r->u);
460b9539 1408}
1409
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1410/** @brief Re-enable reading
1411 * @param r reader
1412 * @return 0 on success, non-0 on error
1413 *
1414 * If there is unconsumed data then you get a callback next time round the
1415 * event loop even if nothing new has been read.
1416 *
1417 * The idea is in your read callback you come across a line (or whatever) that
1418 * can't be processed immediately. So you set up processing and disable
1419 * reading with ev_reader_disable(). Later when you finish processing you
1420 * re-enable. You'll automatically get another callback directly from the
1421 * event loop (i.e. not from inside ev_reader_enable()) so you can handle the
1422 * next line (or whatever) if the whole thing has in fact already arrived.
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1423 *
1424 * The difference between this process and calling ev_reader_incomplete() is
1425 * ev_reader_incomplete() deals with the case where you can process now but
1426 * would rather yield to other clients of the event loop, while using
1427 * ev_reader_disable() and ev_reader_enable() deals with the case where you
1428 * cannot process input yet because some other process is actually not
1429 * complete.
768d7355 1430 */
460b9539 1431int ev_reader_enable(ev_reader *r) {
1432 D(("enable reader fd %d", r->fd));
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1433
1434 /* First if we're not at EOF then we re-enable reading */
1435 if(!r->eof)
1436 if(ev_fd_enable(r->ev, ev_read, r->fd))
1437 return -1;
1438 /* Arrange another callback next time round the event loop */
1439 return ev_timeout(r->ev, 0, 0, reader_enabled, r);
1440}
1441
1442/** @brief Tie a reader and a writer together
1443 * @param r Reader
1444 * @param w Writer
1445 * @return 0 on success, non-0 on error
1446 *
1447 * This function must be called if @p r and @p w share a file descritptor.
1448 */
1449int ev_tie(ev_reader *r, ev_writer *w) {
1450 assert(r->writer == 0);
1451 assert(w->reader == 0);
1452 r->writer = w;
1453 w->reader = r;
1454 return 0;
460b9539 1455}
1456
1457/*
1458Local Variables:
1459c-basic-offset:2
1460comment-column:40
1461fill-column:79
1462End:
1463*/