xref: /openbmc/qemu/io/channel.c (revision e6a41a04) 
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 "io/channel.h"
23 #include "qapi/error.h"
24 #include "qemu/main-loop.h"
25 #include "qemu/module.h"
26 #include "qemu/iov.h"
27 
28 bool qio_channel_has_feature(QIOChannel *ioc,
29                              QIOChannelFeature feature)
30 {
31     return ioc->features & (1 << feature);
32 }
33 
34 
35 void qio_channel_set_feature(QIOChannel *ioc,
36                              QIOChannelFeature feature)
37 {
38     ioc->features |= (1 << feature);
39 }
40 
41 
42 void qio_channel_set_name(QIOChannel *ioc,
43                           const char *name)
44 {
45     g_free(ioc->name);
46     ioc->name = g_strdup(name);
47 }
48 
49 
50 ssize_t qio_channel_readv_full(QIOChannel *ioc,
51                                const struct iovec *iov,
52                                size_t niov,
53                                int **fds,
54                                size_t *nfds,
55                                Error **errp)
56 {
57     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
58 
59     if ((fds || nfds) &&
60         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
61         error_setg_errno(errp, EINVAL,
62                          "Channel does not support file descriptor passing");
63         return -1;
64     }
65 
66     return klass->io_readv(ioc, iov, niov, fds, nfds, errp);
67 }
68 
69 
70 ssize_t qio_channel_writev_full(QIOChannel *ioc,
71                                 const struct iovec *iov,
72                                 size_t niov,
73                                 int *fds,
74                                 size_t nfds,
75                                 Error **errp)
76 {
77     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
78 
79     if ((fds || nfds) &&
80         !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
81         error_setg_errno(errp, EINVAL,
82                          "Channel does not support file descriptor passing");
83         return -1;
84     }
85 
86     return klass->io_writev(ioc, iov, niov, fds, nfds, errp);
87 }
88 
89 
90 int qio_channel_readv_all_eof(QIOChannel *ioc,
91                               const struct iovec *iov,
92                               size_t niov,
93                               Error **errp)
94 {
95     return qio_channel_readv_full_all_eof(ioc, iov, niov, NULL, NULL, errp);
96 }
97 
98 int qio_channel_readv_all(QIOChannel *ioc,
99                           const struct iovec *iov,
100                           size_t niov,
101                           Error **errp)
102 {
103     return qio_channel_readv_full_all(ioc, iov, niov, NULL, NULL, errp);
104 }
105 
106 int qio_channel_readv_full_all_eof(QIOChannel *ioc,
107                                    const struct iovec *iov,
108                                    size_t niov,
109                                    int **fds, size_t *nfds,
110                                    Error **errp)
111 {
112     int ret = -1;
113     struct iovec *local_iov = g_new(struct iovec, niov);
114     struct iovec *local_iov_head = local_iov;
115     unsigned int nlocal_iov = niov;
116     int **local_fds = fds;
117     size_t *local_nfds = nfds;
118     bool partial = false;
119 
120     if (nfds) {
121         *nfds = 0;
122     }
123 
124     if (fds) {
125         *fds = NULL;
126     }
127 
128     nlocal_iov = iov_copy(local_iov, nlocal_iov,
129                           iov, niov,
130                           0, iov_size(iov, niov));
131 
132     while ((nlocal_iov > 0) || local_fds) {
133         ssize_t len;
134         len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
135                                      local_nfds, errp);
136         if (len == QIO_CHANNEL_ERR_BLOCK) {
137             if (qemu_in_coroutine()) {
138                 qio_channel_yield(ioc, G_IO_IN);
139             } else {
140                 qio_channel_wait(ioc, G_IO_IN);
141             }
142             continue;
143         }
144 
145         if (len == 0) {
146             if (local_nfds && *local_nfds) {
147                 /*
148                  * Got some FDs, but no data yet. This isn't an EOF
149                  * scenario (yet), so carry on to try to read data
150                  * on next loop iteration
151                  */
152                 goto next_iter;
153             } else if (!partial) {
154                 /* No fds and no data - EOF before any data read */
155                 ret = 0;
156                 goto cleanup;
157             } else {
158                 len = -1;
159                 error_setg(errp,
160                            "Unexpected end-of-file before all data were read");
161                 /* Fallthrough into len < 0 handling */
162             }
163         }
164 
165         if (len < 0) {
166             /* Close any FDs we previously received */
167             if (nfds && fds) {
168                 size_t i;
169                 for (i = 0; i < (*nfds); i++) {
170                     close((*fds)[i]);
171                 }
172                 g_free(*fds);
173                 *fds = NULL;
174                 *nfds = 0;
175             }
176             goto cleanup;
177         }
178 
179         if (nlocal_iov) {
180             iov_discard_front(&local_iov, &nlocal_iov, len);
181         }
182 
183 next_iter:
184         partial = true;
185         local_fds = NULL;
186         local_nfds = NULL;
187     }
188 
189     ret = 1;
190 
191  cleanup:
192     g_free(local_iov_head);
193     return ret;
194 }
195 
196 int qio_channel_readv_full_all(QIOChannel *ioc,
197                                const struct iovec *iov,
198                                size_t niov,
199                                int **fds, size_t *nfds,
200                                Error **errp)
201 {
202     int ret = qio_channel_readv_full_all_eof(ioc, iov, niov, fds, nfds, errp);
203 
204     if (ret == 0) {
205         error_prepend(errp,
206                       "Unexpected end-of-file before all data were read.");
207         return -1;
208     }
209     if (ret == 1) {
210         return 0;
211     }
212 
213     return ret;
214 }
215 
216 int qio_channel_writev_all(QIOChannel *ioc,
217                            const struct iovec *iov,
218                            size_t niov,
219                            Error **errp)
220 {
221     return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, errp);
222 }
223 
224 int qio_channel_writev_full_all(QIOChannel *ioc,
225                                 const struct iovec *iov,
226                                 size_t niov,
227                                 int *fds, size_t nfds,
228                                 Error **errp)
229 {
230     int ret = -1;
231     struct iovec *local_iov = g_new(struct iovec, niov);
232     struct iovec *local_iov_head = local_iov;
233     unsigned int nlocal_iov = niov;
234 
235     nlocal_iov = iov_copy(local_iov, nlocal_iov,
236                           iov, niov,
237                           0, iov_size(iov, niov));
238 
239     while (nlocal_iov > 0) {
240         ssize_t len;
241         len = qio_channel_writev_full(ioc, local_iov, nlocal_iov, fds, nfds,
242                                       errp);
243         if (len == QIO_CHANNEL_ERR_BLOCK) {
244             if (qemu_in_coroutine()) {
245                 qio_channel_yield(ioc, G_IO_OUT);
246             } else {
247                 qio_channel_wait(ioc, G_IO_OUT);
248             }
249             continue;
250         }
251         if (len < 0) {
252             goto cleanup;
253         }
254 
255         iov_discard_front(&local_iov, &nlocal_iov, len);
256 
257         fds = NULL;
258         nfds = 0;
259     }
260 
261     ret = 0;
262  cleanup:
263     g_free(local_iov_head);
264     return ret;
265 }
266 
267 ssize_t qio_channel_readv(QIOChannel *ioc,
268                           const struct iovec *iov,
269                           size_t niov,
270                           Error **errp)
271 {
272     return qio_channel_readv_full(ioc, iov, niov, NULL, NULL, errp);
273 }
274 
275 
276 ssize_t qio_channel_writev(QIOChannel *ioc,
277                            const struct iovec *iov,
278                            size_t niov,
279                            Error **errp)
280 {
281     return qio_channel_writev_full(ioc, iov, niov, NULL, 0, errp);
282 }
283 
284 
285 ssize_t qio_channel_read(QIOChannel *ioc,
286                          char *buf,
287                          size_t buflen,
288                          Error **errp)
289 {
290     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
291     return qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, errp);
292 }
293 
294 
295 ssize_t qio_channel_write(QIOChannel *ioc,
296                           const char *buf,
297                           size_t buflen,
298                           Error **errp)
299 {
300     struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
301     return qio_channel_writev_full(ioc, &iov, 1, NULL, 0, errp);
302 }
303 
304 
305 int qio_channel_read_all_eof(QIOChannel *ioc,
306                              char *buf,
307                              size_t buflen,
308                              Error **errp)
309 {
310     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
311     return qio_channel_readv_all_eof(ioc, &iov, 1, errp);
312 }
313 
314 
315 int qio_channel_read_all(QIOChannel *ioc,
316                          char *buf,
317                          size_t buflen,
318                          Error **errp)
319 {
320     struct iovec iov = { .iov_base = buf, .iov_len = buflen };
321     return qio_channel_readv_all(ioc, &iov, 1, errp);
322 }
323 
324 
325 int qio_channel_write_all(QIOChannel *ioc,
326                           const char *buf,
327                           size_t buflen,
328                           Error **errp)
329 {
330     struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
331     return qio_channel_writev_all(ioc, &iov, 1, errp);
332 }
333 
334 
335 int qio_channel_set_blocking(QIOChannel *ioc,
336                               bool enabled,
337                               Error **errp)
338 {
339     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
340     return klass->io_set_blocking(ioc, enabled, errp);
341 }
342 
343 
344 int qio_channel_close(QIOChannel *ioc,
345                       Error **errp)
346 {
347     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
348     return klass->io_close(ioc, errp);
349 }
350 
351 
352 GSource *qio_channel_create_watch(QIOChannel *ioc,
353                                   GIOCondition condition)
354 {
355     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
356     GSource *ret = klass->io_create_watch(ioc, condition);
357 
358     if (ioc->name) {
359         g_source_set_name(ret, ioc->name);
360     }
361 
362     return ret;
363 }
364 
365 
366 void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
367                                     AioContext *ctx,
368                                     IOHandler *io_read,
369                                     IOHandler *io_write,
370                                     void *opaque)
371 {
372     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
373 
374     klass->io_set_aio_fd_handler(ioc, ctx, io_read, io_write, opaque);
375 }
376 
377 guint qio_channel_add_watch_full(QIOChannel *ioc,
378                                  GIOCondition condition,
379                                  QIOChannelFunc func,
380                                  gpointer user_data,
381                                  GDestroyNotify notify,
382                                  GMainContext *context)
383 {
384     GSource *source;
385     guint id;
386 
387     source = qio_channel_create_watch(ioc, condition);
388 
389     g_source_set_callback(source, (GSourceFunc)func, user_data, notify);
390 
391     id = g_source_attach(source, context);
392     g_source_unref(source);
393 
394     return id;
395 }
396 
397 guint qio_channel_add_watch(QIOChannel *ioc,
398                             GIOCondition condition,
399                             QIOChannelFunc func,
400                             gpointer user_data,
401                             GDestroyNotify notify)
402 {
403     return qio_channel_add_watch_full(ioc, condition, func,
404                                       user_data, notify, NULL);
405 }
406 
407 GSource *qio_channel_add_watch_source(QIOChannel *ioc,
408                                       GIOCondition condition,
409                                       QIOChannelFunc func,
410                                       gpointer user_data,
411                                       GDestroyNotify notify,
412                                       GMainContext *context)
413 {
414     GSource *source;
415     guint id;
416 
417     id = qio_channel_add_watch_full(ioc, condition, func,
418                                     user_data, notify, context);
419     source = g_main_context_find_source_by_id(context, id);
420     g_source_ref(source);
421     return source;
422 }
423 
424 
425 int qio_channel_shutdown(QIOChannel *ioc,
426                          QIOChannelShutdown how,
427                          Error **errp)
428 {
429     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
430 
431     if (!klass->io_shutdown) {
432         error_setg(errp, "Data path shutdown not supported");
433         return -1;
434     }
435 
436     return klass->io_shutdown(ioc, how, errp);
437 }
438 
439 
440 void qio_channel_set_delay(QIOChannel *ioc,
441                            bool enabled)
442 {
443     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
444 
445     if (klass->io_set_delay) {
446         klass->io_set_delay(ioc, enabled);
447     }
448 }
449 
450 
451 void qio_channel_set_cork(QIOChannel *ioc,
452                           bool enabled)
453 {
454     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
455 
456     if (klass->io_set_cork) {
457         klass->io_set_cork(ioc, enabled);
458     }
459 }
460 
461 
462 off_t qio_channel_io_seek(QIOChannel *ioc,
463                           off_t offset,
464                           int whence,
465                           Error **errp)
466 {
467     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
468 
469     if (!klass->io_seek) {
470         error_setg(errp, "Channel does not support random access");
471         return -1;
472     }
473 
474     return klass->io_seek(ioc, offset, whence, errp);
475 }
476 
477 
478 static void qio_channel_restart_read(void *opaque)
479 {
480     QIOChannel *ioc = opaque;
481     Coroutine *co = ioc->read_coroutine;
482 
483     /* Assert that aio_co_wake() reenters the coroutine directly */
484     assert(qemu_get_current_aio_context() ==
485            qemu_coroutine_get_aio_context(co));
486     aio_co_wake(co);
487 }
488 
489 static void qio_channel_restart_write(void *opaque)
490 {
491     QIOChannel *ioc = opaque;
492     Coroutine *co = ioc->write_coroutine;
493 
494     /* Assert that aio_co_wake() reenters the coroutine directly */
495     assert(qemu_get_current_aio_context() ==
496            qemu_coroutine_get_aio_context(co));
497     aio_co_wake(co);
498 }
499 
500 static void qio_channel_set_aio_fd_handlers(QIOChannel *ioc)
501 {
502     IOHandler *rd_handler = NULL, *wr_handler = NULL;
503     AioContext *ctx;
504 
505     if (ioc->read_coroutine) {
506         rd_handler = qio_channel_restart_read;
507     }
508     if (ioc->write_coroutine) {
509         wr_handler = qio_channel_restart_write;
510     }
511 
512     ctx = ioc->ctx ? ioc->ctx : iohandler_get_aio_context();
513     qio_channel_set_aio_fd_handler(ioc, ctx, rd_handler, wr_handler, ioc);
514 }
515 
516 void qio_channel_attach_aio_context(QIOChannel *ioc,
517                                     AioContext *ctx)
518 {
519     assert(!ioc->read_coroutine);
520     assert(!ioc->write_coroutine);
521     ioc->ctx = ctx;
522 }
523 
524 void qio_channel_detach_aio_context(QIOChannel *ioc)
525 {
526     ioc->read_coroutine = NULL;
527     ioc->write_coroutine = NULL;
528     qio_channel_set_aio_fd_handlers(ioc);
529     ioc->ctx = NULL;
530 }
531 
532 void coroutine_fn qio_channel_yield(QIOChannel *ioc,
533                                     GIOCondition condition)
534 {
535     assert(qemu_in_coroutine());
536     if (condition == G_IO_IN) {
537         assert(!ioc->read_coroutine);
538         ioc->read_coroutine = qemu_coroutine_self();
539     } else if (condition == G_IO_OUT) {
540         assert(!ioc->write_coroutine);
541         ioc->write_coroutine = qemu_coroutine_self();
542     } else {
543         abort();
544     }
545     qio_channel_set_aio_fd_handlers(ioc);
546     qemu_coroutine_yield();
547 
548     /* Allow interrupting the operation by reentering the coroutine other than
549      * through the aio_fd_handlers. */
550     if (condition == G_IO_IN && ioc->read_coroutine) {
551         ioc->read_coroutine = NULL;
552         qio_channel_set_aio_fd_handlers(ioc);
553     } else if (condition == G_IO_OUT && ioc->write_coroutine) {
554         ioc->write_coroutine = NULL;
555         qio_channel_set_aio_fd_handlers(ioc);
556     }
557 }
558 
559 
560 static gboolean qio_channel_wait_complete(QIOChannel *ioc,
561                                           GIOCondition condition,
562                                           gpointer opaque)
563 {
564     GMainLoop *loop = opaque;
565 
566     g_main_loop_quit(loop);
567     return FALSE;
568 }
569 
570 
571 void qio_channel_wait(QIOChannel *ioc,
572                       GIOCondition condition)
573 {
574     GMainContext *ctxt = g_main_context_new();
575     GMainLoop *loop = g_main_loop_new(ctxt, TRUE);
576     GSource *source;
577 
578     source = qio_channel_create_watch(ioc, condition);
579 
580     g_source_set_callback(source,
581                           (GSourceFunc)qio_channel_wait_complete,
582                           loop,
583                           NULL);
584 
585     g_source_attach(source, ctxt);
586 
587     g_main_loop_run(loop);
588 
589     g_source_unref(source);
590     g_main_loop_unref(loop);
591     g_main_context_unref(ctxt);
592 }
593 
594 
595 static void qio_channel_finalize(Object *obj)
596 {
597     QIOChannel *ioc = QIO_CHANNEL(obj);
598 
599     g_free(ioc->name);
600 
601 #ifdef _WIN32
602     if (ioc->event) {
603         CloseHandle(ioc->event);
604     }
605 #endif
606 }
607 
608 static const TypeInfo qio_channel_info = {
609     .parent = TYPE_OBJECT,
610     .name = TYPE_QIO_CHANNEL,
611     .instance_size = sizeof(QIOChannel),
612     .instance_finalize = qio_channel_finalize,
613     .abstract = true,
614     .class_size = sizeof(QIOChannelClass),
615 };
616 
617 
618 static void qio_channel_register_types(void)
619 {
620     type_register_static(&qio_channel_info);
621 }
622 
623 
624 type_init(qio_channel_register_types);
625