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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 *
164 * Ought to be in @file lib/timeval.h
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) {
391 D(("enabling mode %s fd %d", modenames[mode], fd));
392 FD_SET(fd, &ev->mode[mode].enabled);
393 return 0;
394}
395
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396/** @brief Temporarily disable a file descriptor
397 * @param ev Event loop
398 * @param mode @c ev_read or @c ev_write
399 * @param fd File descriptor
400 * @return 0 on success, non-0 on error
401 *
402 * Re-enable with ev_fd_enable(). It is harmless if @p fd is already disabled,
403 * but it must not have been cancelled.
404 */
460b9539 405int ev_fd_disable(ev_source *ev, ev_fdmode mode, int fd) {
406 D(("disabling mode %s fd %d", modenames[mode], fd));
407 FD_CLR(fd, &ev->mode[mode].enabled);
408 FD_CLR(fd, &ev->mode[mode].tripped);
409 return 0;
410}
411
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412/** @brief Log a report of file descriptor state */
413void ev_report(ev_source *ev) {
414 int n, fd;
415 ev_fdmode mode;
416 struct dynstr d[1];
417 char b[4096];
418
419 dynstr_init(d);
420 for(mode = 0; mode < ev_nmodes; ++mode) {
421 info("mode %s maxfd %d", modenames[mode], ev->mode[mode].maxfd);
422 for(n = 0; n < ev->mode[mode].nfds; ++n) {
423 fd = ev->mode[mode].fds[n].fd;
424 info("fd %s %d%s%s (%s)", modenames[mode], fd,
425 FD_ISSET(fd, &ev->mode[mode].enabled) ? " enabled" : "",
426 FD_ISSET(fd, &ev->mode[mode].tripped) ? " tripped" : "",
427 ev->mode[mode].fds[n].what);
428 }
429 d->nvec = 0;
430 for(fd = 0; fd <= ev->mode[mode].maxfd; ++fd) {
431 if(!FD_ISSET(fd, &ev->mode[mode].enabled))
432 continue;
433 for(n = 0; n < ev->mode[mode].nfds; ++n) {
434 if(ev->mode[mode].fds[n].fd == fd)
435 break;
436 }
437 if(n < ev->mode[mode].nfds)
34a3e246 438 snprintf(b, sizeof b, "%d(%s)", fd, ev->mode[mode].fds[n].what);
768d7355 439 else
34a3e246 440 snprintf(b, sizeof b, "%d", fd);
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441 dynstr_append(d, ' ');
442 dynstr_append_string(d, b);
443 }
444 dynstr_terminate(d);
445 info("%s enabled:%s", modenames[mode], d->vec);
446 }
447}
448
460b9539 449/* timeouts *******************************************************************/
450
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451/** @brief Register a timeout
452 * @param ev Event source
453 * @param handle Where to store timeout handle, or @c NULL
454 * @param when Earliest time to call @p callback, or @c NULL
455 * @param callback Function to call at or after @p when
456 * @param u Passed to @p callback
457 * @return 0 on success, non-0 on error
458 *
459 * If @p when is a null pointer then a time of 0 is assumed. The effect is to
460 * call the timeout handler from ev_run() next time around the event loop.
461 * This is used internally to schedule various operations if it is not
462 * convenient to call them from the current place in the call stack, or
463 * externally to ensure that other clients of the event loop get a look in when
464 * performing some lengthy operation.
465 */
460b9539 466int ev_timeout(ev_source *ev,
467 ev_timeout_handle *handlep,
468 const struct timeval *when,
469 ev_timeout_callback *callback,
470 void *u) {
471 struct timeout *t, *p, **pp;
472
473 D(("registering timeout at %ld.%ld callback %p %p",
474 when ? (long)when->tv_sec : 0, when ? (long)when->tv_usec : 0,
475 (void *)callback, u));
476 t = xmalloc(sizeof *t);
477 if(when)
478 t->when = *when;
479 t->callback = callback;
480 t->u = u;
481 pp = &ev->timeouts;
482 while((p = *pp) && gt(&t->when, &p->when))
483 pp = &p->next;
484 t->next = p;
485 *pp = t;
486 if(handlep)
487 *handlep = t;
488 return 0;
489}
490
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491/** @brief Cancel a timeout
492 * @param ev Event loop
cb9a695c 493 * @param handle Handle returned from ev_timeout(), or 0
768d7355 494 * @return 0 on success, non-0 on error
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495 *
496 * If @p handle is 0 then this is a no-op.
768d7355 497 */
460b9539 498int ev_timeout_cancel(ev_source *ev,
499 ev_timeout_handle handle) {
500 struct timeout *t = handle, *p, **pp;
501
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502 if(!t)
503 return 0;
460b9539 504 for(pp = &ev->timeouts; (p = *pp) && p != t; pp = &p->next)
505 ;
506 if(p) {
507 *pp = p->next;
508 return 0;
509 } else
510 return -1;
511}
512
513/* signals ********************************************************************/
514
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515/** @brief Mapping of signals to pipe write ends
516 *
517 * The pipes are per-event loop, it's possible in theory for there to be
518 * multiple event loops (e.g. in different threads), although in fact DisOrder
519 * does not do this.
520 */
460b9539 521static int sigfd[NSIG];
522
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523/** @brief The signal handler
524 * @param s Signal number
525 *
526 * Writes to @c sigfd[s].
527 */
460b9539 528static void sighandler(int s) {
529 unsigned char sc = s;
530 static const char errmsg[] = "error writing to signal pipe";
531
532 /* probably the reader has stopped listening for some reason */
533 if(write(sigfd[s], &sc, 1) < 0) {
534 write(2, errmsg, sizeof errmsg - 1);
535 abort();
536 }
537}
538
768d7355 539/** @brief Read callback for signals */
460b9539 540static int signal_read(ev_source *ev,
541 int attribute((unused)) fd,
542 void attribute((unused)) *u) {
543 unsigned char s;
544 int n;
545 int ret;
546
547 if((n = read(ev->sigpipe[0], &s, 1)) == 1)
548 if((ret = ev->signals[s].callback(ev, s, ev->signals[s].u)))
549 return ret;
550 assert(n != 0);
551 if(n < 0 && (errno != EINTR && errno != EAGAIN)) {
552 error(errno, "error reading from signal pipe %d", ev->sigpipe[0]);
553 return -1;
554 }
555 return 0;
556}
557
768d7355 558/** @brief Close the signal pipe */
460b9539 559static void close_sigpipe(ev_source *ev) {
560 int save_errno = errno;
561
562 xclose(ev->sigpipe[0]);
563 xclose(ev->sigpipe[1]);
564 ev->sigpipe[0] = ev->sigpipe[1] = -1;
565 errno = save_errno;
566}
567
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568/** @brief Register a signal handler
569 * @param ev Event loop
570 * @param sig Signal to handle
571 * @param callback Called when signal is delivered
572 * @param u Passed to @p callback
573 * @return 0 on success, non-0 on error
574 *
575 * Note that @p callback is called from inside ev_run(), not from inside the
576 * signal handler, so the usual restrictions on signal handlers do not apply.
577 */
460b9539 578int ev_signal(ev_source *ev,
579 int sig,
580 ev_signal_callback *callback,
581 void *u) {
582 int n;
583 struct sigaction sa;
584
585 D(("registering signal %d handler callback %p %p", sig, (void *)callback, u));
586 assert(sig > 0);
587 assert(sig < NSIG);
588 assert(sig <= UCHAR_MAX);
589 if(ev->sigpipe[0] == -1) {
590 D(("creating signal pipe"));
591 xpipe(ev->sigpipe);
592 D(("signal pipe is %d, %d", ev->sigpipe[0], ev->sigpipe[1]));
593 for(n = 0; n < 2; ++n) {
594 nonblock(ev->sigpipe[n]);
595 cloexec(ev->sigpipe[n]);
596 }
e8c92ba7 597 if(ev_fd(ev, ev_read, ev->sigpipe[0], signal_read, 0, "sigpipe read")) {
460b9539 598 close_sigpipe(ev);
599 return -1;
600 }
601 }
602 sigaddset(&ev->sigmask, sig);
603 xsigprocmask(SIG_BLOCK, &ev->sigmask, 0);
604 sigfd[sig] = ev->sigpipe[1];
605 ev->signals[sig].callback = callback;
606 ev->signals[sig].u = u;
607 sa.sa_handler = sighandler;
608 sigfillset(&sa.sa_mask);
609 sa.sa_flags = SA_RESTART;
610 xsigaction(sig, &sa, &ev->signals[sig].oldsa);
611 ev->escape = 1;
612 return 0;
613}
614
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615/** @brief Cancel a signal handler
616 * @param ev Event loop
617 * @param sig Signal to cancel
618 * @return 0 on success, non-0 on error
619 */
460b9539 620int ev_signal_cancel(ev_source *ev,
621 int sig) {
622 sigset_t ss;
623
624 xsigaction(sig, &ev->signals[sig].oldsa, 0);
625 ev->signals[sig].callback = 0;
626 ev->escape = 1;
627 sigdelset(&ev->sigmask, sig);
628 sigemptyset(&ss);
629 sigaddset(&ss, sig);
630 xsigprocmask(SIG_UNBLOCK, &ss, 0);
631 return 0;
632}
633
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634/** @brief Clean up signal handling
635 * @param ev Event loop
636 *
637 * This function can be called from inside a fork. It restores signal
638 * handlers, unblocks the signals, and closes the signal pipe for @p ev.
639 */
460b9539 640void ev_signal_atfork(ev_source *ev) {
641 int sig;
642
643 if(ev->sigpipe[0] != -1) {
644 /* revert any handled signals to their original state */
645 for(sig = 1; sig < NSIG; ++sig) {
646 if(ev->signals[sig].callback != 0)
647 xsigaction(sig, &ev->signals[sig].oldsa, 0);
648 }
649 /* and then unblock them */
650 xsigprocmask(SIG_UNBLOCK, &ev->sigmask, 0);
651 /* don't want a copy of the signal pipe open inside the fork */
652 xclose(ev->sigpipe[0]);
653 xclose(ev->sigpipe[1]);
654 }
655}
656
657/* child processes ************************************************************/
658
768d7355 659/** @brief Called on SIGCHLD */
460b9539 660static int sigchld_callback(ev_source *ev,
661 int attribute((unused)) sig,
662 void attribute((unused)) *u) {
663 struct rusage ru;
664 pid_t r;
665 int status, n, ret, revisit;
666
667 do {
668 revisit = 0;
669 for(n = 0; n < ev->nchildren; ++n) {
670 r = wait4(ev->children[n].pid,
671 &status,
672 ev->children[n].options | WNOHANG,
673 &ru);
674 if(r > 0) {
675 ev_child_callback *c = ev->children[n].callback;
676 void *cu = ev->children[n].u;
677
678 if(WIFEXITED(status) || WIFSIGNALED(status))
679 ev_child_cancel(ev, r);
680 revisit = 1;
681 if((ret = c(ev, r, status, &ru, cu)))
682 return ret;
683 } else if(r < 0) {
684 /* We should "never" get an ECHILD but it can in fact happen. For
685 * instance on Linux 2.4.31, and probably other versions, if someone
686 * straces a child process and then a different child process
687 * terminates, when we wait4() the trace process we will get ECHILD
688 * because it has been reparented to strace. Obviously this is a
689 * hopeless design flaw in the tracing infrastructure, but we don't
690 * want the disorder server to bomb out because of it. So we just log
691 * the problem and ignore it.
692 */
693 error(errno, "error calling wait4 for PID %lu (broken ptrace?)",
694 (unsigned long)ev->children[n].pid);
695 if(errno != ECHILD)
696 return -1;
697 }
698 }
699 } while(revisit);
700 return 0;
701}
702
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703/** @brief Configure event loop for child process handling
704 * @return 0 on success, non-0 on error
705 *
706 * Currently at most one event loop can handle child processes and it must be
707 * distinguished from others by calling this function on it. This could be
708 * fixed but since no process ever makes use of more than one event loop there
709 * is no need.
710 */
460b9539 711int ev_child_setup(ev_source *ev) {
712 D(("installing SIGCHLD handler"));
713 return ev_signal(ev, SIGCHLD, sigchld_callback, 0);
714}
715
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716/** @brief Wait for a child process to terminate
717 * @param ev Event loop
718 * @param pid Process ID of child
719 * @param options Options to pass to @c wait4()
720 * @param callback Called when child terminates (or possibly when it stops)
721 * @param u Passed to @p callback
722 * @return 0 on success, non-0 on error
723 *
724 * You must have called ev_child_setup() on @p ev once first.
725 */
460b9539 726int ev_child(ev_source *ev,
727 pid_t pid,
728 int options,
729 ev_child_callback *callback,
730 void *u) {
731 int n;
732
733 D(("registering child handling %ld options %d callback %p %p",
734 (long)pid, options, (void *)callback, u));
735 assert(ev->signals[SIGCHLD].callback == sigchld_callback);
736 if(ev->nchildren >= ev->nchildslots) {
737 ev->nchildslots = ev->nchildslots ? 2 * ev->nchildslots : 16;
738 ev->children = xrealloc(ev->children,
739 ev->nchildslots * sizeof (struct child));
740 }
741 n = ev->nchildren++;
742 ev->children[n].pid = pid;
743 ev->children[n].options = options;
744 ev->children[n].callback = callback;
745 ev->children[n].u = u;
746 return 0;
747}
748
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749/** @brief Stop waiting for a child process
750 * @param ev Event loop
751 * @param pid Child process ID
752 * @return 0 on success, non-0 on error
753 */
460b9539 754int ev_child_cancel(ev_source *ev,
755 pid_t pid) {
756 int n;
757
758 for(n = 0; n < ev->nchildren && ev->children[n].pid != pid; ++n)
759 ;
760 assert(n < ev->nchildren);
761 if(n != ev->nchildren - 1)
762 ev->children[n] = ev->children[ev->nchildren - 1];
763 --ev->nchildren;
764 return 0;
765}
766
767/* socket listeners ***********************************************************/
768
768d7355 769/** @brief State for a socket listener */
460b9539 770struct listen_state {
771 ev_listen_callback *callback;
772 void *u;
773};
774
768d7355 775/** @brief Called when a listenign socket is readable */
460b9539 776static int listen_callback(ev_source *ev, int fd, void *u) {
777 const struct listen_state *l = u;
778 int newfd;
779 union {
780 struct sockaddr_in in;
781#if HAVE_STRUCT_SOCKADDR_IN6
782 struct sockaddr_in6 in6;
783#endif
784 struct sockaddr_un un;
785 struct sockaddr sa;
786 } addr;
787 socklen_t addrlen;
788 int ret;
789
790 D(("callback for listener fd %d", fd));
791 while((addrlen = sizeof addr),
792 (newfd = accept(fd, &addr.sa, &addrlen)) >= 0) {
793 if((ret = l->callback(ev, newfd, &addr.sa, addrlen, l->u)))
794 return ret;
795 }
796 switch(errno) {
797 case EINTR:
798 case EAGAIN:
799 break;
800#ifdef ECONNABORTED
801 case ECONNABORTED:
802 error(errno, "error calling accept");
803 break;
804#endif
805#ifdef EPROTO
806 case EPROTO:
807 /* XXX on some systems EPROTO should be fatal, but we don't know if
808 * we're running on one of them */
809 error(errno, "error calling accept");
810 break;
811#endif
812 default:
813 fatal(errno, "error calling accept");
814 break;
815 }
816 if(errno != EINTR && errno != EAGAIN)
817 error(errno, "error calling accept");
818 return 0;
819}
820
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821/** @brief Listen on a socket for inbound stream connections
822 * @param ev Event source
823 * @param fd File descriptor of socket
824 * @param callback Called when a new connection arrives
825 * @param u Passed to @p callback
826 * @param what Text description of socket
827 * @return 0 on success, non-0 on error
828 */
460b9539 829int ev_listen(ev_source *ev,
830 int fd,
831 ev_listen_callback *callback,
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832 void *u,
833 const char *what) {
460b9539 834 struct listen_state *l = xmalloc(sizeof *l);
835
836 D(("registering listener fd %d callback %p %p", fd, (void *)callback, u));
837 l->callback = callback;
838 l->u = u;
e8c92ba7 839 return ev_fd(ev, ev_read, fd, listen_callback, l, what);
460b9539 840}
841
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842/** @brief Stop listening on a socket
843 * @param ev Event loop
844 * @param fd File descriptor of socket
845 * @return 0 on success, non-0 on error
846 */
460b9539 847int ev_listen_cancel(ev_source *ev, int fd) {
848 D(("cancelling listener fd %d", fd));
849 return ev_fd_cancel(ev, ev_read, fd);
850}
851
852/* buffer *********************************************************************/
853
768d7355 854/** @brief Buffer structure */
460b9539 855struct buffer {
856 char *base, *start, *end, *top;
857};
858
768d7355 859/* @brief Make sure there is @p bytes available at @c b->end */
460b9539 860static void buffer_space(struct buffer *b, size_t bytes) {
861 D(("buffer_space %p %p %p %p want %lu",
862 (void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top,
863 (unsigned long)bytes));
864 if(b->start == b->end)
865 b->start = b->end = b->base;
866 if((size_t)(b->top - b->end) < bytes) {
867 if((size_t)((b->top - b->end) + (b->start - b->base)) < bytes) {
868 size_t newspace = b->end - b->start + bytes, n;
869 char *newbase;
870
871 for(n = 16; n < newspace; n *= 2)
872 ;
873 newbase = xmalloc_noptr(n);
874 memcpy(newbase, b->start, b->end - b->start);
875 b->base = newbase;
876 b->end = newbase + (b->end - b->start);
877 b->top = newbase + n;
878 b->start = newbase; /* must be last */
879 } else {
880 memmove(b->base, b->start, b->end - b->start);
881 b->end = b->base + (b->end - b->start);
882 b->start = b->base;
883 }
884 }
885 D(("result %p %p %p %p",
886 (void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top));
887}
888
889/* buffered writer ************************************************************/
890
768d7355 891/** @brief State structure for a buffered writer */
460b9539 892struct ev_writer {
893 struct sink s;
894 struct buffer b;
895 int fd;
896 int eof;
897 ev_error_callback *callback;
898 void *u;
899 ev_source *ev;
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900
901 /** @brief Maximum amount of time between succesful writes, 0 = don't care */
902 int timebound;
903 /** @brief Maximum amount of data to buffer, 0 = don't care */
904 int spacebound;
905 /** @brief Synthesized error code */
906 int syntherror;
907 /** @brief Timeout handle for @p timebound (or 0) */
908 ev_timeout_handle timeout;
909
910 const char *what;
460b9539 911};
912
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913/** @brief Synthesized error callback
914 *
915 * Calls @p callback with @p w->syntherr as the error code (which might be 0).
916 */
917static int writer_shutdown(ev_source *ev,
918 const attribute((unused)) struct timeval *now,
919 void *u) {
920 ev_writer *w = u;
e4a9c7c5 921 int fd;
cb9a695c 922
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923 if(w->fd == -1)
924 return 0; /* already closed */
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925 ev_timeout_cancel(ev, w->timeout);
926 w->timeout = 0;
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927 fd = w->fd;
928 w->fd = -1;
929 return w->callback(ev, fd, w->syntherror, w->u);
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930}
931
932/** @brief Called when a writer's @p timebound expires */
933static int writer_timebound_exceeded(ev_source *ev,
934 const struct timeval attribute((unused)) *now,
935 void *u) {
936 ev_writer *const w = u;
e4a9c7c5 937 int fd;
cb9a695c 938
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939 if(w->fd == -1)
940 return 0; /* already closed */
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941 error(0, "abandoning writer %s because no writes within %ds",
942 w->what, w->timebound);
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943 fd = w->fd;
944 w->fd = -1;
945 return w->callback(ev, fd, ETIMEDOUT, w->u);
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946}
947
948/** @brief Set the time bound callback (if not set already) */
949static void writer_set_timebound(ev_writer *w) {
950 if(w->timebound && !w->timeout) {
951 struct timeval when;
952 ev_source *const ev = w->ev;
953
954 xgettimeofday(&when, 0);
955 when.tv_sec += w->timebound;
956 ev_timeout(ev, &w->timeout, &when, writer_timebound_exceeded, w);
957 }
958}
959
768d7355 960/** @brief Called when a writer's file descriptor is writable */
460b9539 961static int writer_callback(ev_source *ev, int fd, void *u) {
cb9a695c 962 ev_writer *const w = u;
460b9539 963 int n;
964
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965 if(w->fd == -1)
966 return 0;
460b9539 967 n = write(fd, w->b.start, w->b.end - w->b.start);
968 D(("callback for writer fd %d, %ld bytes, n=%d, errno=%d",
969 fd, (long)(w->b.end - w->b.start), n, errno));
970 if(n >= 0) {
971 w->b.start += n;
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972 ev_timeout_cancel(ev, w->timeout);
973 w->timeout = 0;
460b9539 974 if(w->b.start == w->b.end) {
975 if(w->eof) {
976 ev_fd_cancel(ev, ev_write, fd);
e4a9c7c5 977 w->fd = -1;
460b9539 978 return w->callback(ev, fd, 0, w->u);
979 } else
980 ev_fd_disable(ev, ev_write, fd);
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981 } else
982 writer_set_timebound(w);
460b9539 983 } else {
984 switch(errno) {
985 case EINTR:
986 case EAGAIN:
987 break;
988 default:
989 ev_fd_cancel(ev, ev_write, fd);
e4a9c7c5 990 w->fd = -1;
460b9539 991 return w->callback(ev, fd, errno, w->u);
992 }
993 }
994 return 0;
995}
996
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997/** @brief Write bytes to a writer's buffer
998 *
999 * This is the sink write callback.
1000 *
1001 * Calls ev_fd_enable() if necessary (i.e. if the buffer was empty but
1002 * now is not).
1003 */
460b9539 1004static int ev_writer_write(struct sink *sk, const void *s, int n) {
1005 ev_writer *w = (ev_writer *)sk;
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1006
1007 if(!n)
1008 return 0; /* avoid silliness */
460b9539 1009 buffer_space(&w->b, n);
1010 if(w->b.start == w->b.end)
1011 ev_fd_enable(w->ev, ev_write, w->fd);
1012 memcpy(w->b.end, s, n);
1013 w->b.end += n;
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1014 if(w->spacebound && w->b.end - w->b.start > w->spacebound) {
1015 /* Buffer contents have exceeded the space bound. We assume that the
1016 * remote client has gone away and TCP hasn't noticed yet, or that it's got
1017 * hopelessly stuck. */
1018 error(0, "abandoning writer %s because buffer has reached %td bytes",
1019 w->what, w->b.end - w->b.start);
1020 w->syntherror = EPIPE;
1021 ev_fd_cancel(w->ev, ev_write, w->fd);
1022 return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
1023 }
1024 writer_set_timebound(w);
460b9539 1025 return 0;
1026}
1027
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1028/** @brief Create a new buffered writer
1029 * @param ev Event loop
1030 * @param fd File descriptor to write to
1031 * @param callback Called if an error occurs and when finished
1032 * @param u Passed to @p callback
1033 * @param what Text description
1034 * @return New writer or @c NULL
1035 */
460b9539 1036ev_writer *ev_writer_new(ev_source *ev,
1037 int fd,
1038 ev_error_callback *callback,
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1039 void *u,
1040 const char *what) {
460b9539 1041 ev_writer *w = xmalloc(sizeof *w);
1042
1043 D(("registering writer fd %d callback %p %p", fd, (void *)callback, u));
1044 w->s.write = ev_writer_write;
1045 w->fd = fd;
1046 w->callback = callback;
1047 w->u = u;
1048 w->ev = ev;
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1049 w->timebound = 10 * 60;
1050 w->spacebound = 512 * 1024;
1051 w->what = what;
e8c92ba7 1052 if(ev_fd(ev, ev_write, fd, writer_callback, w, what))
460b9539 1053 return 0;
1054 ev_fd_disable(ev, ev_write, fd);
1055 return w;
1056}
1057
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1058/** @brief Get/set the time bound
1059 * @param w Writer
1060 * @param new_time_bound New bound or -1 for no change
1061 * @return Latest time bound
1062 *
1063 * If @p new_time_bound is negative then the current time bound is returned.
1064 * Otherwise it is set and the new value returned.
1065 *
1066 * The time bound is the number of seconds allowed between writes. If it takes
1067 * longer than this to flush a buffer then the peer will be assumed to be dead
1068 * and an error will be synthesized. 0 means "don't care". The default time
1069 * bound is 10 minutes.
1070 *
1071 * Note that this value does not take into account kernel buffering and
1072 * timeouts.
1073 */
1074int ev_writer_time_bound(ev_writer *w,
1075 int new_time_bound) {
1076 if(new_time_bound >= 0)
1077 w->timebound = new_time_bound;
1078 return w->timebound;
1079}
1080
1081/** @brief Get/set the space bound
1082 * @param w Writer
1083 * @param new_space_bound New bound or -1 for no change
1084 * @return Latest space bound
1085 *
1086 * If @p new_space_bound is negative then the current space bound is returned.
1087 * Otherwise it is set and the new value returned.
1088 *
1089 * The space bound is the number of bytes allowed between in the buffer. If
1090 * the buffer exceeds this size an error will be synthesized. 0 means "don't
1091 * care". The default space bound is 512Kbyte.
1092 *
1093 * Note that this value does not take into account kernel buffering.
1094 */
1095int ev_writer_space_bound(ev_writer *w,
1096 int new_space_bound) {
1097 if(new_space_bound >= 0)
1098 w->spacebound = new_space_bound;
1099 return w->spacebound;
1100}
1101
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1102/** @brief Return the sink associated with a writer
1103 * @param w Writer
1104 * @return Pointer to sink
1105 *
1106 * Writing to the sink will arrange for those bytes to be written to the file
1107 * descriptor as and when it is writable.
1108 */
460b9539 1109struct sink *ev_writer_sink(ev_writer *w) {
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1110 if(!w)
1111 fatal(0, "ev_write_sink called with null writer");
460b9539 1112 return &w->s;
1113}
1114
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1115/** @brief Close a writer
1116 * @param w Writer to close
1117 * @return 0 on success, non-0 on error
1118 *
1119 * Close a writer. No more bytes should be written to its sink.
1120 *
1121 * When the last byte has been written the callback will be called with an
1122 * error code of 0. It is guaranteed that this will NOT happen before
1123 * ev_writer_close() returns (although the file descriptor for the writer might
1124 * be cancelled by the time it returns).
1125 */
460b9539 1126int ev_writer_close(ev_writer *w) {
1127 D(("close writer fd %d", w->fd));
1128 w->eof = 1;
1129 if(w->b.start == w->b.end) {
1130 /* we're already finished */
cb9a695c 1131 w->syntherror = 0; /* no error */
460b9539 1132 ev_fd_cancel(w->ev, ev_write, w->fd);
1133 return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
1134 }
1135 return 0;
1136}
1137
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1138/** @brief Cancel a writer discarding any buffered data
1139 * @param w Writer to close
1140 * @return 0 on success, non-0 on error
1141 *
1142 * This cancels a writer immediately. Any unwritten buffered data is discarded
1143 * and the error callback is never called. This is appropriate to call if (for
1144 * instance) the read half of a TCP connection is known to have failed and the
1145 * writer is therefore obsolete.
1146 */
460b9539 1147int ev_writer_cancel(ev_writer *w) {
cb9a695c 1148 ev_source *const ev = w->ev;
460b9539 1149 D(("cancel writer fd %d", w->fd));
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1150 ev_timeout_cancel(ev, w->timeout);
1151 w->timeout = 0;
460b9539 1152 return ev_fd_cancel(w->ev, ev_write, w->fd);
1153}
1154
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1155/** @brief Attempt to flush a writer
1156 * @param w Writer to flush
1157 * @return 0 on success, non-0 on error
1158 *
1159 * Does a speculative write of any buffered data. Does not block if it cannot
1160 * be written.
1161 */
460b9539 1162int ev_writer_flush(ev_writer *w) {
1163 return writer_callback(w->ev, w->fd, w);
1164}
1165
1166/* buffered reader ************************************************************/
1167
768d7355 1168/** @brief State structure for a buffered reader */
460b9539 1169struct ev_reader {
1170 struct buffer b;
1171 int fd;
1172 ev_reader_callback *callback;
1173 ev_error_callback *error_callback;
1174 void *u;
1175 ev_source *ev;
1176 int eof;
1177};
1178
768d7355 1179/** @brief Called when a reader's @p fd is readable */
460b9539 1180static int reader_callback(ev_source *ev, int fd, void *u) {
1181 ev_reader *r = u;
1182 int n;
1183
1184 buffer_space(&r->b, 1);
1185 n = read(fd, r->b.end, r->b.top - r->b.end);
1186 D(("read fd %d buffer %d returned %d errno %d",
1187 fd, (int)(r->b.top - r->b.end), n, errno));
1188 if(n > 0) {
1189 r->b.end += n;
1190 return r->callback(ev, r, fd, r->b.start, r->b.end - r->b.start, 0, r->u);
1191 } else if(n == 0) {
1192 r->eof = 1;
1193 ev_fd_cancel(ev, ev_read, fd);
1194 return r->callback(ev, r, fd, r->b.start, r->b.end - r->b.start, 1, r->u);
1195 } else {
1196 switch(errno) {
1197 case EINTR:
1198 case EAGAIN:
1199 break;
1200 default:
1201 ev_fd_cancel(ev, ev_read, fd);
1202 return r->error_callback(ev, fd, errno, r->u);
1203 }
1204 }
1205 return 0;
1206}
1207
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1208/** @brief Create a new buffered reader
1209 * @param ev Event loop
1210 * @param fd File descriptor to read from
1211 * @param callback Called when new data is available
1212 * @param error_callback Called if an error occurs
1213 * @param u Passed to callbacks
1214 * @param what Text description
1215 * @return New reader or @c NULL
1216 */
460b9539 1217ev_reader *ev_reader_new(ev_source *ev,
1218 int fd,
1219 ev_reader_callback *callback,
1220 ev_error_callback *error_callback,
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1221 void *u,
1222 const char *what) {
460b9539 1223 ev_reader *r = xmalloc(sizeof *r);
1224
1225 D(("registering reader fd %d callback %p %p %p",
1226 fd, (void *)callback, (void *)error_callback, u));
1227 r->fd = fd;
1228 r->callback = callback;
1229 r->error_callback = error_callback;
1230 r->u = u;
1231 r->ev = ev;
e8c92ba7 1232 if(ev_fd(ev, ev_read, fd, reader_callback, r, what))
460b9539 1233 return 0;
1234 return r;
1235}
1236
1237void ev_reader_buffer(ev_reader *r, size_t nbytes) {
1238 buffer_space(&r->b, nbytes - (r->b.end - r->b.start));
1239}
1240
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1241/** @brief Consume @p n bytes from the reader's buffer
1242 * @param r Reader
1243 * @param n Number of bytes to consume
1244 *
1245 * Tells the reader than the next @p n bytes have been dealt with and can now
1246 * be discarded.
1247 */
460b9539 1248void ev_reader_consume(ev_reader *r, size_t n) {
1249 r->b.start += n;
1250}
1251
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1252/** @brief Cancel a reader
1253 * @param r Reader
1254 * @return 0 on success, non-0 on error
1255 */
460b9539 1256int ev_reader_cancel(ev_reader *r) {
1257 D(("cancel reader fd %d", r->fd));
1258 return ev_fd_cancel(r->ev, ev_read, r->fd);
1259}
1260
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1261/** @brief Temporarily disable a reader
1262 * @param r Reader
1263 * @return 0 on success, non-0 on error
1264 *
1265 * No further callbacks for this reader will be made. Re-enable with
1266 * ev_reader_enable().
1267 */
460b9539 1268int ev_reader_disable(ev_reader *r) {
1269 D(("disable reader fd %d", r->fd));
1270 return r->eof ? 0 : ev_fd_disable(r->ev, ev_read, r->fd);
1271}
1272
768d7355 1273/** @brief Called from ev_run() for ev_reader_incomplete() */
460b9539 1274static int reader_continuation(ev_source attribute((unused)) *ev,
1275 const attribute((unused)) struct timeval *now,
1276 void *u) {
1277 ev_reader *r = u;
1278
1279 D(("reader continuation callback fd %d", r->fd));
1280 if(ev_fd_enable(r->ev, ev_read, r->fd)) return -1;
1281 return r->callback(ev, r, r->fd, r->b.start, r->b.end - r->b.start, r->eof, r->u);
1282}
1283
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1284/** @brief Arrange another callback
1285 * @param r reader
1286 * @return 0 on success, non-0 on error
1287 *
1288 * Indicates that the reader can process more input but would like to yield to
1289 * other clients of the event loop. Input will be disabled but it will be
1290 * re-enabled on the next iteration of the event loop and the read callback
1291 * will be called again (even if no further bytes are available).
1292 */
460b9539 1293int ev_reader_incomplete(ev_reader *r) {
1294 if(ev_fd_disable(r->ev, ev_read, r->fd)) return -1;
1295 return ev_timeout(r->ev, 0, 0, reader_continuation, r);
1296}
1297
1298static int reader_enabled(ev_source *ev,
1299 const attribute((unused)) struct timeval *now,
1300 void *u) {
1301 ev_reader *r = u;
1302
1303 D(("reader enabled callback fd %d", r->fd));
1304 return r->callback(ev, r, r->fd, r->b.start, r->b.end - r->b.start, r->eof, r->u);
1305}
1306
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1307/** @brief Re-enable reading
1308 * @param r reader
1309 * @return 0 on success, non-0 on error
1310 *
1311 * If there is unconsumed data then you get a callback next time round the
1312 * event loop even if nothing new has been read.
1313 *
1314 * The idea is in your read callback you come across a line (or whatever) that
1315 * can't be processed immediately. So you set up processing and disable
1316 * reading with ev_reader_disable(). Later when you finish processing you
1317 * re-enable. You'll automatically get another callback directly from the
1318 * event loop (i.e. not from inside ev_reader_enable()) so you can handle the
1319 * next line (or whatever) if the whole thing has in fact already arrived.
1320 */
460b9539 1321int ev_reader_enable(ev_reader *r) {
1322 D(("enable reader fd %d", r->fd));
1323 return ((r->eof ? 0 : ev_fd_enable(r->ev, ev_read, r->fd))
1324 || ev_timeout(r->ev, 0, 0, reader_enabled, r)) ? -1 : 0;
1325}
1326
1327/*
1328Local Variables:
1329c-basic-offset:2
1330comment-column:40
1331fill-column:79
1332End:
1333*/