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buildsys: Bump known good meson version to v1.2.3
[qmiga/qemu.git] / io / channel.c
1 /*
2  * QEMU I/O channels
3  *
4  * Copyright (c) 2015 Red Hat, Inc.
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  *
19  */
20
21 #include "qemu/osdep.h"
22 #include "block/aio-wait.h"
23 #include "io/channel.h"
24 #include "qapi/error.h"
25 #include "qemu/main-loop.h"
26 #include "qemu/module.h"
27 #include "qemu/iov.h"
28
29 bool qio_channel_has_feature(QIOChannel *ioc,
30                              QIOChannelFeature feature)
31 {
32     return ioc->features & (1 << feature);
33 }
34
35
36 void qio_channel_set_feature(QIOChannel *ioc,
37                              QIOChannelFeature feature)
38 {
39     ioc->features |= (1 << feature);
40 }
41
42
43 void qio_channel_set_name(QIOChannel *ioc,
44                           const char *name)
45 {
46     g_free(ioc->name);
47     ioc->name = g_strdup(name);
48 }
49
50
51 ssize_t qio_channel_readv_full(QIOChannel *ioc,
52                                const struct iovec *iov,
53                                size_t niov,
54                                int **fds,
55                                size_t *nfds,
56                                int flags,
57                                Error **errp)
58 {
59     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
60
61     if ((fds || nfds) &&
62         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
63         error_setg_errno(errp, EINVAL,
64                          "Channel does not support file descriptor passing");
65         return -1;
66     }
67
68     if ((flags & QIO_CHANNEL_READ_FLAG_MSG_PEEK) &&
69         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
70         error_setg_errno(errp, EINVAL,
71                          "Channel does not support peek read");
72         return -1;
73     }
74
75     return klass->io_readv(ioc, iov, niov, fds, nfds, flags, errp);
76 }
77
78
79 ssize_t qio_channel_writev_full(QIOChannel *ioc,
80                                 const struct iovec *iov,
81                                 size_t niov,
82                                 int *fds,
83                                 size_t nfds,
84                                 int flags,
85                                 Error **errp)
86 {
87     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
88
89     if (fds || nfds) {
90         if (!qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
91             error_setg_errno(errp, EINVAL,
92                              "Channel does not support file descriptor passing");
93             return -1;
94         }
95         if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) {
96             error_setg_errno(errp, EINVAL,
97                              "Zero Copy does not support file descriptor passing");
98             return -1;
99         }
100     }
101
102     if ((flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) &&
103         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
104         error_setg_errno(errp, EINVAL,
105                          "Requested Zero Copy feature is not available");
106         return -1;
107     }
108
109     return klass->io_writev(ioc, iov, niov, fds, nfds, flags, errp);
110 }
111
112
113 int coroutine_mixed_fn qio_channel_readv_all_eof(QIOChannel *ioc,
114                                                  const struct iovec *iov,
115                                                  size_t niov,
116                                                  Error **errp)
117 {
118     return qio_channel_readv_full_all_eof(ioc, iov, niov, NULL, NULL, errp);
119 }
120
121 int coroutine_mixed_fn qio_channel_readv_all(QIOChannel *ioc,
122                                              const struct iovec *iov,
123                                              size_t niov,
124                                              Error **errp)
125 {
126     return qio_channel_readv_full_all(ioc, iov, niov, NULL, NULL, errp);
127 }
128
129 int coroutine_mixed_fn qio_channel_readv_full_all_eof(QIOChannel *ioc,
130                                                       const struct iovec *iov,
131                                                       size_t niov,
132                                                       int **fds, size_t *nfds,
133                                                       Error **errp)
134 {
135     int ret = -1;
136     struct iovec *local_iov = g_new(struct iovec, niov);
137     struct iovec *local_iov_head = local_iov;
138     unsigned int nlocal_iov = niov;
139     int **local_fds = fds;
140     size_t *local_nfds = nfds;
141     bool partial = false;
142
143     if (nfds) {
144         *nfds = 0;
145     }
146
147     if (fds) {
148         *fds = NULL;
149     }
150
151     nlocal_iov = iov_copy(local_iov, nlocal_iov,
152                           iov, niov,
153                           0, iov_size(iov, niov));
154
155     while ((nlocal_iov > 0) || local_fds) {
156         ssize_t len;
157         len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
158                                      local_nfds, 0, errp);
159         if (len == QIO_CHANNEL_ERR_BLOCK) {
160             if (qemu_in_coroutine()) {
161                 qio_channel_yield(ioc, G_IO_IN);
162             } else {
163                 qio_channel_wait(ioc, G_IO_IN);
164             }
165             continue;
166         }
167
168         if (len == 0) {
169             if (local_nfds && *local_nfds) {
170                 /*
171                  * Got some FDs, but no data yet. This isn't an EOF
172                  * scenario (yet), so carry on to try to read data
173                  * on next loop iteration
174                  */
175                 goto next_iter;
176             } else if (!partial) {
177                 /* No fds and no data - EOF before any data read */
178                 ret = 0;
179                 goto cleanup;
180             } else {
181                 len = -1;
182                 error_setg(errp,
183                            "Unexpected end-of-file before all data were read");
184                 /* Fallthrough into len < 0 handling */
185             }
186         }
187
188         if (len < 0) {
189             /* Close any FDs we previously received */
190             if (nfds && fds) {
191                 size_t i;
192                 for (i = 0; i < (*nfds); i++) {
193                     close((*fds)[i]);
194                 }
195                 g_free(*fds);
196                 *fds = NULL;
197                 *nfds = 0;
198             }
199             goto cleanup;
200         }
201
202         if (nlocal_iov) {
203             iov_discard_front(&local_iov, &nlocal_iov, len);
204         }
205
206 next_iter:
207         partial = true;
208         local_fds = NULL;
209         local_nfds = NULL;
210     }
211
212     ret = 1;
213
214  cleanup:
215     g_free(local_iov_head);
216     return ret;
217 }
218
219 int coroutine_mixed_fn qio_channel_readv_full_all(QIOChannel *ioc,
220                                                   const struct iovec *iov,
221                                                   size_t niov,
222                                                   int **fds, size_t *nfds,
223                                                   Error **errp)
224 {
225     int ret = qio_channel_readv_full_all_eof(ioc, iov, niov, fds, nfds, errp);
226
227     if (ret == 0) {
228         error_setg(errp, "Unexpected end-of-file before all data were read");
229         return -1;
230     }
231     if (ret == 1) {
232         return 0;
233     }
234
235     return ret;
236 }
237
238 int coroutine_mixed_fn qio_channel_writev_all(QIOChannel *ioc,
239                                               const struct iovec *iov,
240                                               size_t niov,
241                                               Error **errp)
242 {
243     return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, 0, errp);
244 }
245
246 int coroutine_mixed_fn qio_channel_writev_full_all(QIOChannel *ioc,
247                                                    const struct iovec *iov,
248                                                    size_t niov,
249                                                    int *fds, size_t nfds,
250                                                    int flags, Error **errp)
251 {
252     int ret = -1;
253     struct iovec *local_iov = g_new(struct iovec, niov);
254     struct iovec *local_iov_head = local_iov;
255     unsigned int nlocal_iov = niov;
256
257     nlocal_iov = iov_copy(local_iov, nlocal_iov,
258                           iov, niov,
259                           0, iov_size(iov, niov));
260
261     while (nlocal_iov > 0) {
262         ssize_t len;
263
264         len = qio_channel_writev_full(ioc, local_iov, nlocal_iov, fds,
265                                             nfds, flags, errp);
266
267         if (len == QIO_CHANNEL_ERR_BLOCK) {
268             if (qemu_in_coroutine()) {
269                 qio_channel_yield(ioc, G_IO_OUT);
270             } else {
271                 qio_channel_wait(ioc, G_IO_OUT);
272             }
273             continue;
274         }
275         if (len < 0) {
276             goto cleanup;
277         }
278
279         iov_discard_front(&local_iov, &nlocal_iov, len);
280
281         fds = NULL;
282         nfds = 0;
283     }
284
285     ret = 0;
286  cleanup:
287     g_free(local_iov_head);
288     return ret;
289 }
290
291 ssize_t qio_channel_readv(QIOChannel *ioc,
292                           const struct iovec *iov,
293                           size_t niov,
294                           Error **errp)
295 {
296     return qio_channel_readv_full(ioc, iov, niov, NULL, NULL, 0, errp);
297 }
298
299
300 ssize_t qio_channel_writev(QIOChannel *ioc,
301                            const struct iovec *iov,
302                            size_t niov,
303                            Error **errp)
304 {
305     return qio_channel_writev_full(ioc, iov, niov, NULL, 0, 0, errp);
306 }
307
308
309 ssize_t qio_channel_read(QIOChannel *ioc,
310                          char *buf,
311                          size_t buflen,
312                          Error **errp)
313 {
314     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
315     return qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, 0, errp);
316 }
317
318
319 ssize_t qio_channel_write(QIOChannel *ioc,
320                           const char *buf,
321                           size_t buflen,
322                           Error **errp)
323 {
324     struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
325     return qio_channel_writev_full(ioc, &iov, 1, NULL, 0, 0, errp);
326 }
327
328
329 int coroutine_mixed_fn qio_channel_read_all_eof(QIOChannel *ioc,
330                                                 char *buf,
331                                                 size_t buflen,
332                                                 Error **errp)
333 {
334     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
335     return qio_channel_readv_all_eof(ioc, &iov, 1, errp);
336 }
337
338
339 int coroutine_mixed_fn qio_channel_read_all(QIOChannel *ioc,
340                                             char *buf,
341                                             size_t buflen,
342                                             Error **errp)
343 {
344     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
345     return qio_channel_readv_all(ioc, &iov, 1, errp);
346 }
347
348
349 int coroutine_mixed_fn qio_channel_write_all(QIOChannel *ioc,
350                                              const char *buf,
351                                              size_t buflen,
352                                              Error **errp)
353 {
354     struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
355     return qio_channel_writev_all(ioc, &iov, 1, errp);
356 }
357
358
359 int qio_channel_set_blocking(QIOChannel *ioc,
360                               bool enabled,
361                               Error **errp)
362 {
363     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
364     return klass->io_set_blocking(ioc, enabled, errp);
365 }
366
367
368 void qio_channel_set_follow_coroutine_ctx(QIOChannel *ioc, bool enabled)
369 {
370     ioc->follow_coroutine_ctx = enabled;
371 }
372
373
374 int qio_channel_close(QIOChannel *ioc,
375                       Error **errp)
376 {
377     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
378     return klass->io_close(ioc, errp);
379 }
380
381
382 GSource *qio_channel_create_watch(QIOChannel *ioc,
383                                   GIOCondition condition)
384 {
385     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
386     GSource *ret = klass->io_create_watch(ioc, condition);
387
388     if (ioc->name) {
389         g_source_set_name(ret, ioc->name);
390     }
391
392     return ret;
393 }
394
395
396 void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
397                                     AioContext *read_ctx,
398                                     IOHandler *io_read,
399                                     AioContext *write_ctx,
400                                     IOHandler *io_write,
401                                     void *opaque)
402 {
403     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
404
405     klass->io_set_aio_fd_handler(ioc, read_ctx, io_read, write_ctx, io_write,
406             opaque);
407 }
408
409 guint qio_channel_add_watch_full(QIOChannel *ioc,
410                                  GIOCondition condition,
411                                  QIOChannelFunc func,
412                                  gpointer user_data,
413                                  GDestroyNotify notify,
414                                  GMainContext *context)
415 {
416     GSource *source;
417     guint id;
418
419     source = qio_channel_create_watch(ioc, condition);
420
421     g_source_set_callback(source, (GSourceFunc)func, user_data, notify);
422
423     id = g_source_attach(source, context);
424     g_source_unref(source);
425
426     return id;
427 }
428
429 guint qio_channel_add_watch(QIOChannel *ioc,
430                             GIOCondition condition,
431                             QIOChannelFunc func,
432                             gpointer user_data,
433                             GDestroyNotify notify)
434 {
435     return qio_channel_add_watch_full(ioc, condition, func,
436                                       user_data, notify, NULL);
437 }
438
439 GSource *qio_channel_add_watch_source(QIOChannel *ioc,
440                                       GIOCondition condition,
441                                       QIOChannelFunc func,
442                                       gpointer user_data,
443                                       GDestroyNotify notify,
444                                       GMainContext *context)
445 {
446     GSource *source;
447     guint id;
448
449     id = qio_channel_add_watch_full(ioc, condition, func,
450                                     user_data, notify, context);
451     source = g_main_context_find_source_by_id(context, id);
452     g_source_ref(source);
453     return source;
454 }
455
456
457 int qio_channel_shutdown(QIOChannel *ioc,
458                          QIOChannelShutdown how,
459                          Error **errp)
460 {
461     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
462
463     if (!klass->io_shutdown) {
464         error_setg(errp, "Data path shutdown not supported");
465         return -1;
466     }
467
468     return klass->io_shutdown(ioc, how, errp);
469 }
470
471
472 void qio_channel_set_delay(QIOChannel *ioc,
473                            bool enabled)
474 {
475     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
476
477     if (klass->io_set_delay) {
478         klass->io_set_delay(ioc, enabled);
479     }
480 }
481
482
483 void qio_channel_set_cork(QIOChannel *ioc,
484                           bool enabled)
485 {
486     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
487
488     if (klass->io_set_cork) {
489         klass->io_set_cork(ioc, enabled);
490     }
491 }
492
493
494 off_t qio_channel_io_seek(QIOChannel *ioc,
495                           off_t offset,
496                           int whence,
497                           Error **errp)
498 {
499     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
500
501     if (!klass->io_seek) {
502         error_setg(errp, "Channel does not support random access");
503         return -1;
504     }
505
506     return klass->io_seek(ioc, offset, whence, errp);
507 }
508
509 int qio_channel_flush(QIOChannel *ioc,
510                                 Error **errp)
511 {
512     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
513
514     if (!klass->io_flush ||
515         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
516         return 0;
517     }
518
519     return klass->io_flush(ioc, errp);
520 }
521
522
523 static void qio_channel_restart_read(void *opaque)
524 {
525     QIOChannel *ioc = opaque;
526     Coroutine *co = qatomic_xchg(&ioc->read_coroutine, NULL);
527
528     if (!co) {
529         return;
530     }
531
532     /* Assert that aio_co_wake() reenters the coroutine directly */
533     assert(qemu_get_current_aio_context() ==
534            qemu_coroutine_get_aio_context(co));
535     aio_co_wake(co);
536 }
537
538 static void qio_channel_restart_write(void *opaque)
539 {
540     QIOChannel *ioc = opaque;
541     Coroutine *co = qatomic_xchg(&ioc->write_coroutine, NULL);
542
543     if (!co) {
544         return;
545     }
546
547     /* Assert that aio_co_wake() reenters the coroutine directly */
548     assert(qemu_get_current_aio_context() ==
549            qemu_coroutine_get_aio_context(co));
550     aio_co_wake(co);
551 }
552
553 static void coroutine_fn
554 qio_channel_set_fd_handlers(QIOChannel *ioc, GIOCondition condition)
555 {
556     AioContext *ctx = ioc->follow_coroutine_ctx ?
557         qemu_coroutine_get_aio_context(qemu_coroutine_self()) :
558         iohandler_get_aio_context();
559     AioContext *read_ctx = NULL;
560     IOHandler *io_read = NULL;
561     AioContext *write_ctx = NULL;
562     IOHandler *io_write = NULL;
563
564     if (condition == G_IO_IN) {
565         ioc->read_coroutine = qemu_coroutine_self();
566         ioc->read_ctx = ctx;
567         read_ctx = ctx;
568         io_read = qio_channel_restart_read;
569
570         /*
571          * Thread safety: if the other coroutine is set and its AioContext
572          * matches ours, then there is mutual exclusion between read and write
573          * because they share a single thread and it's safe to set both read
574          * and write fd handlers here. If the AioContext does not match ours,
575          * then both threads may run in parallel but there is no shared state
576          * to worry about.
577          */
578         if (ioc->write_coroutine && ioc->write_ctx == ctx) {
579             write_ctx = ctx;
580             io_write = qio_channel_restart_write;
581         }
582     } else if (condition == G_IO_OUT) {
583         ioc->write_coroutine = qemu_coroutine_self();
584         ioc->write_ctx = ctx;
585         write_ctx = ctx;
586         io_write = qio_channel_restart_write;
587         if (ioc->read_coroutine && ioc->read_ctx == ctx) {
588             read_ctx = ctx;
589             io_read = qio_channel_restart_read;
590         }
591     } else {
592         abort();
593     }
594
595     qio_channel_set_aio_fd_handler(ioc, read_ctx, io_read,
596             write_ctx, io_write, ioc);
597 }
598
599 static void coroutine_fn
600 qio_channel_clear_fd_handlers(QIOChannel *ioc, GIOCondition condition)
601 {
602     AioContext *read_ctx = NULL;
603     IOHandler *io_read = NULL;
604     AioContext *write_ctx = NULL;
605     IOHandler *io_write = NULL;
606     AioContext *ctx;
607
608     if (condition == G_IO_IN) {
609         ctx = ioc->read_ctx;
610         read_ctx = ctx;
611         io_read = NULL;
612         if (ioc->write_coroutine && ioc->write_ctx == ctx) {
613             write_ctx = ctx;
614             io_write = qio_channel_restart_write;
615         }
616     } else if (condition == G_IO_OUT) {
617         ctx = ioc->write_ctx;
618         write_ctx = ctx;
619         io_write = NULL;
620         if (ioc->read_coroutine && ioc->read_ctx == ctx) {
621             read_ctx = ctx;
622             io_read = qio_channel_restart_read;
623         }
624     } else {
625         abort();
626     }
627
628     qio_channel_set_aio_fd_handler(ioc, read_ctx, io_read,
629             write_ctx, io_write, ioc);
630 }
631
632 void coroutine_fn qio_channel_yield(QIOChannel *ioc,
633                                     GIOCondition condition)
634 {
635     AioContext *ioc_ctx;
636
637     assert(qemu_in_coroutine());
638     ioc_ctx = qemu_coroutine_get_aio_context(qemu_coroutine_self());
639
640     if (condition == G_IO_IN) {
641         assert(!ioc->read_coroutine);
642     } else if (condition == G_IO_OUT) {
643         assert(!ioc->write_coroutine);
644     } else {
645         abort();
646     }
647     qio_channel_set_fd_handlers(ioc, condition);
648     qemu_coroutine_yield();
649     assert(in_aio_context_home_thread(ioc_ctx));
650
651     /* Allow interrupting the operation by reentering the coroutine other than
652      * through the aio_fd_handlers. */
653     if (condition == G_IO_IN) {
654         assert(ioc->read_coroutine == NULL);
655     } else if (condition == G_IO_OUT) {
656         assert(ioc->write_coroutine == NULL);
657     }
658     qio_channel_clear_fd_handlers(ioc, condition);
659 }
660
661 void qio_channel_wake_read(QIOChannel *ioc)
662 {
663     Coroutine *co = qatomic_xchg(&ioc->read_coroutine, NULL);
664     if (co) {
665         aio_co_wake(co);
666     }
667 }
668
669 static gboolean qio_channel_wait_complete(QIOChannel *ioc,
670                                           GIOCondition condition,
671                                           gpointer opaque)
672 {
673     GMainLoop *loop = opaque;
674
675     g_main_loop_quit(loop);
676     return FALSE;
677 }
678
679
680 void qio_channel_wait(QIOChannel *ioc,
681                       GIOCondition condition)
682 {
683     GMainContext *ctxt = g_main_context_new();
684     GMainLoop *loop = g_main_loop_new(ctxt, TRUE);
685     GSource *source;
686
687     source = qio_channel_create_watch(ioc, condition);
688
689     g_source_set_callback(source,
690                           (GSourceFunc)qio_channel_wait_complete,
691                           loop,
692                           NULL);
693
694     g_source_attach(source, ctxt);
695
696     g_main_loop_run(loop);
697
698     g_source_unref(source);
699     g_main_loop_unref(loop);
700     g_main_context_unref(ctxt);
701 }
702
703
704 static void qio_channel_finalize(Object *obj)
705 {
706     QIOChannel *ioc = QIO_CHANNEL(obj);
707
708     /* Must not have coroutines in qio_channel_yield() */
709     assert(!ioc->read_coroutine);
710     assert(!ioc->write_coroutine);
711
712     g_free(ioc->name);
713
714 #ifdef _WIN32
715     if (ioc->event) {
716         CloseHandle(ioc->event);
717     }
718 #endif
719 }
720
721 static const TypeInfo qio_channel_info = {
722     .parent = TYPE_OBJECT,
723     .name = TYPE_QIO_CHANNEL,
724     .instance_size = sizeof(QIOChannel),
725     .instance_finalize = qio_channel_finalize,
726     .abstract = true,
727     .class_size = sizeof(QIOChannelClass),
728 };
729
730
731 static void qio_channel_register_types(void)
732 {
733     type_register_static(&qio_channel_info);
734 }
735
736
737 type_init(qio_channel_register_types);