migration: introduce set_blocking function in QEMUFileOps
[qemu.git] / migration / qemu-file.c
1 /*
2 * QEMU System Emulator
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24 #include "qemu/osdep.h"
25 #include <zlib.h>
26 #include "qemu-common.h"
27 #include "qemu/error-report.h"
28 #include "qemu/iov.h"
29 #include "qemu/sockets.h"
30 #include "qemu/coroutine.h"
31 #include "migration/migration.h"
32 #include "migration/qemu-file.h"
33 #include "migration/qemu-file-internal.h"
34 #include "trace.h"
35
36 /*
37 * Stop a file from being read/written - not all backing files can do this
38 * typically only sockets can.
39 */
40 int qemu_file_shutdown(QEMUFile *f)
41 {
42 if (!f->ops->shut_down) {
43 return -ENOSYS;
44 }
45 return f->ops->shut_down(f->opaque, true, true);
46 }
47
48 /*
49 * Result: QEMUFile* for a 'return path' for comms in the opposite direction
50 * NULL if not available
51 */
52 QEMUFile *qemu_file_get_return_path(QEMUFile *f)
53 {
54 if (!f->ops->get_return_path) {
55 return NULL;
56 }
57 return f->ops->get_return_path(f->opaque);
58 }
59
60 bool qemu_file_mode_is_not_valid(const char *mode)
61 {
62 if (mode == NULL ||
63 (mode[0] != 'r' && mode[0] != 'w') ||
64 mode[1] != 'b' || mode[2] != 0) {
65 fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
66 return true;
67 }
68
69 return false;
70 }
71
72 QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
73 {
74 QEMUFile *f;
75
76 f = g_new0(QEMUFile, 1);
77
78 f->opaque = opaque;
79 f->ops = ops;
80 return f;
81 }
82
83
84 void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks)
85 {
86 f->hooks = hooks;
87 }
88
89 /*
90 * Get last error for stream f
91 *
92 * Return negative error value if there has been an error on previous
93 * operations, return 0 if no error happened.
94 *
95 */
96 int qemu_file_get_error(QEMUFile *f)
97 {
98 return f->last_error;
99 }
100
101 void qemu_file_set_error(QEMUFile *f, int ret)
102 {
103 if (f->last_error == 0) {
104 f->last_error = ret;
105 }
106 }
107
108 bool qemu_file_is_writable(QEMUFile *f)
109 {
110 return f->ops->writev_buffer || f->ops->put_buffer;
111 }
112
113 /**
114 * Flushes QEMUFile buffer
115 *
116 * If there is writev_buffer QEMUFileOps it uses it otherwise uses
117 * put_buffer ops. This will flush all pending data. If data was
118 * only partially flushed, it will set an error state.
119 */
120 void qemu_fflush(QEMUFile *f)
121 {
122 ssize_t ret = 0;
123 ssize_t expect = 0;
124
125 if (!qemu_file_is_writable(f)) {
126 return;
127 }
128
129 if (f->ops->writev_buffer) {
130 if (f->iovcnt > 0) {
131 expect = iov_size(f->iov, f->iovcnt);
132 ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos);
133 }
134 } else {
135 if (f->buf_index > 0) {
136 expect = f->buf_index;
137 ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index);
138 }
139 }
140
141 if (ret >= 0) {
142 f->pos += ret;
143 }
144 /* We expect the QEMUFile write impl to send the full
145 * data set we requested, so sanity check that.
146 */
147 if (ret != expect) {
148 qemu_file_set_error(f, ret < 0 ? ret : -EIO);
149 }
150 f->buf_index = 0;
151 f->iovcnt = 0;
152 }
153
154 void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
155 {
156 int ret = 0;
157
158 if (f->hooks && f->hooks->before_ram_iterate) {
159 ret = f->hooks->before_ram_iterate(f, f->opaque, flags, NULL);
160 if (ret < 0) {
161 qemu_file_set_error(f, ret);
162 }
163 }
164 }
165
166 void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
167 {
168 int ret = 0;
169
170 if (f->hooks && f->hooks->after_ram_iterate) {
171 ret = f->hooks->after_ram_iterate(f, f->opaque, flags, NULL);
172 if (ret < 0) {
173 qemu_file_set_error(f, ret);
174 }
175 }
176 }
177
178 void ram_control_load_hook(QEMUFile *f, uint64_t flags, void *data)
179 {
180 int ret = -EINVAL;
181
182 if (f->hooks && f->hooks->hook_ram_load) {
183 ret = f->hooks->hook_ram_load(f, f->opaque, flags, data);
184 if (ret < 0) {
185 qemu_file_set_error(f, ret);
186 }
187 } else {
188 /*
189 * Hook is a hook specifically requested by the source sending a flag
190 * that expects there to be a hook on the destination.
191 */
192 if (flags == RAM_CONTROL_HOOK) {
193 qemu_file_set_error(f, ret);
194 }
195 }
196 }
197
198 size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
199 ram_addr_t offset, size_t size,
200 uint64_t *bytes_sent)
201 {
202 if (f->hooks && f->hooks->save_page) {
203 int ret = f->hooks->save_page(f, f->opaque, block_offset,
204 offset, size, bytes_sent);
205
206 if (ret != RAM_SAVE_CONTROL_DELAYED) {
207 if (bytes_sent && *bytes_sent > 0) {
208 qemu_update_position(f, *bytes_sent);
209 } else if (ret < 0) {
210 qemu_file_set_error(f, ret);
211 }
212 }
213
214 return ret;
215 }
216
217 return RAM_SAVE_CONTROL_NOT_SUPP;
218 }
219
220 /*
221 * Attempt to fill the buffer from the underlying file
222 * Returns the number of bytes read, or negative value for an error.
223 *
224 * Note that it can return a partially full buffer even in a not error/not EOF
225 * case if the underlying file descriptor gives a short read, and that can
226 * happen even on a blocking fd.
227 */
228 static ssize_t qemu_fill_buffer(QEMUFile *f)
229 {
230 int len;
231 int pending;
232
233 assert(!qemu_file_is_writable(f));
234
235 pending = f->buf_size - f->buf_index;
236 if (pending > 0) {
237 memmove(f->buf, f->buf + f->buf_index, pending);
238 }
239 f->buf_index = 0;
240 f->buf_size = pending;
241
242 len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
243 IO_BUF_SIZE - pending);
244 if (len > 0) {
245 f->buf_size += len;
246 f->pos += len;
247 } else if (len == 0) {
248 qemu_file_set_error(f, -EIO);
249 } else if (len != -EAGAIN) {
250 qemu_file_set_error(f, len);
251 }
252
253 return len;
254 }
255
256 int qemu_get_fd(QEMUFile *f)
257 {
258 if (f->ops->get_fd) {
259 return f->ops->get_fd(f->opaque);
260 }
261 return -1;
262 }
263
264 void qemu_update_position(QEMUFile *f, size_t size)
265 {
266 f->pos += size;
267 }
268
269 /** Closes the file
270 *
271 * Returns negative error value if any error happened on previous operations or
272 * while closing the file. Returns 0 or positive number on success.
273 *
274 * The meaning of return value on success depends on the specific backend
275 * being used.
276 */
277 int qemu_fclose(QEMUFile *f)
278 {
279 int ret;
280 qemu_fflush(f);
281 ret = qemu_file_get_error(f);
282
283 if (f->ops->close) {
284 int ret2 = f->ops->close(f->opaque);
285 if (ret >= 0) {
286 ret = ret2;
287 }
288 }
289 /* If any error was spotted before closing, we should report it
290 * instead of the close() return value.
291 */
292 if (f->last_error) {
293 ret = f->last_error;
294 }
295 g_free(f);
296 trace_qemu_file_fclose();
297 return ret;
298 }
299
300 static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size)
301 {
302 /* check for adjacent buffer and coalesce them */
303 if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
304 f->iov[f->iovcnt - 1].iov_len) {
305 f->iov[f->iovcnt - 1].iov_len += size;
306 } else {
307 f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
308 f->iov[f->iovcnt++].iov_len = size;
309 }
310
311 if (f->iovcnt >= MAX_IOV_SIZE) {
312 qemu_fflush(f);
313 }
314 }
315
316 void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size)
317 {
318 if (!f->ops->writev_buffer) {
319 qemu_put_buffer(f, buf, size);
320 return;
321 }
322
323 if (f->last_error) {
324 return;
325 }
326
327 f->bytes_xfer += size;
328 add_to_iovec(f, buf, size);
329 }
330
331 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size)
332 {
333 size_t l;
334
335 if (f->last_error) {
336 return;
337 }
338
339 while (size > 0) {
340 l = IO_BUF_SIZE - f->buf_index;
341 if (l > size) {
342 l = size;
343 }
344 memcpy(f->buf + f->buf_index, buf, l);
345 f->bytes_xfer += l;
346 if (f->ops->writev_buffer) {
347 add_to_iovec(f, f->buf + f->buf_index, l);
348 }
349 f->buf_index += l;
350 if (f->buf_index == IO_BUF_SIZE) {
351 qemu_fflush(f);
352 }
353 if (qemu_file_get_error(f)) {
354 break;
355 }
356 buf += l;
357 size -= l;
358 }
359 }
360
361 void qemu_put_byte(QEMUFile *f, int v)
362 {
363 if (f->last_error) {
364 return;
365 }
366
367 f->buf[f->buf_index] = v;
368 f->bytes_xfer++;
369 if (f->ops->writev_buffer) {
370 add_to_iovec(f, f->buf + f->buf_index, 1);
371 }
372 f->buf_index++;
373 if (f->buf_index == IO_BUF_SIZE) {
374 qemu_fflush(f);
375 }
376 }
377
378 void qemu_file_skip(QEMUFile *f, int size)
379 {
380 if (f->buf_index + size <= f->buf_size) {
381 f->buf_index += size;
382 }
383 }
384
385 /*
386 * Read 'size' bytes from file (at 'offset') without moving the
387 * pointer and set 'buf' to point to that data.
388 *
389 * It will return size bytes unless there was an error, in which case it will
390 * return as many as it managed to read (assuming blocking fd's which
391 * all current QEMUFile are)
392 */
393 size_t qemu_peek_buffer(QEMUFile *f, uint8_t **buf, size_t size, size_t offset)
394 {
395 ssize_t pending;
396 size_t index;
397
398 assert(!qemu_file_is_writable(f));
399 assert(offset < IO_BUF_SIZE);
400 assert(size <= IO_BUF_SIZE - offset);
401
402 /* The 1st byte to read from */
403 index = f->buf_index + offset;
404 /* The number of available bytes starting at index */
405 pending = f->buf_size - index;
406
407 /*
408 * qemu_fill_buffer might return just a few bytes, even when there isn't
409 * an error, so loop collecting them until we get enough.
410 */
411 while (pending < size) {
412 int received = qemu_fill_buffer(f);
413
414 if (received <= 0) {
415 break;
416 }
417
418 index = f->buf_index + offset;
419 pending = f->buf_size - index;
420 }
421
422 if (pending <= 0) {
423 return 0;
424 }
425 if (size > pending) {
426 size = pending;
427 }
428
429 *buf = f->buf + index;
430 return size;
431 }
432
433 /*
434 * Read 'size' bytes of data from the file into buf.
435 * 'size' can be larger than the internal buffer.
436 *
437 * It will return size bytes unless there was an error, in which case it will
438 * return as many as it managed to read (assuming blocking fd's which
439 * all current QEMUFile are)
440 */
441 size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size)
442 {
443 size_t pending = size;
444 size_t done = 0;
445
446 while (pending > 0) {
447 size_t res;
448 uint8_t *src;
449
450 res = qemu_peek_buffer(f, &src, MIN(pending, IO_BUF_SIZE), 0);
451 if (res == 0) {
452 return done;
453 }
454 memcpy(buf, src, res);
455 qemu_file_skip(f, res);
456 buf += res;
457 pending -= res;
458 done += res;
459 }
460 return done;
461 }
462
463 /*
464 * Read 'size' bytes of data from the file.
465 * 'size' can be larger than the internal buffer.
466 *
467 * The data:
468 * may be held on an internal buffer (in which case *buf is updated
469 * to point to it) that is valid until the next qemu_file operation.
470 * OR
471 * will be copied to the *buf that was passed in.
472 *
473 * The code tries to avoid the copy if possible.
474 *
475 * It will return size bytes unless there was an error, in which case it will
476 * return as many as it managed to read (assuming blocking fd's which
477 * all current QEMUFile are)
478 *
479 * Note: Since **buf may get changed, the caller should take care to
480 * keep a pointer to the original buffer if it needs to deallocate it.
481 */
482 size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size)
483 {
484 if (size < IO_BUF_SIZE) {
485 size_t res;
486 uint8_t *src;
487
488 res = qemu_peek_buffer(f, &src, size, 0);
489
490 if (res == size) {
491 qemu_file_skip(f, res);
492 *buf = src;
493 return res;
494 }
495 }
496
497 return qemu_get_buffer(f, *buf, size);
498 }
499
500 /*
501 * Peeks a single byte from the buffer; this isn't guaranteed to work if
502 * offset leaves a gap after the previous read/peeked data.
503 */
504 int qemu_peek_byte(QEMUFile *f, int offset)
505 {
506 int index = f->buf_index + offset;
507
508 assert(!qemu_file_is_writable(f));
509 assert(offset < IO_BUF_SIZE);
510
511 if (index >= f->buf_size) {
512 qemu_fill_buffer(f);
513 index = f->buf_index + offset;
514 if (index >= f->buf_size) {
515 return 0;
516 }
517 }
518 return f->buf[index];
519 }
520
521 int qemu_get_byte(QEMUFile *f)
522 {
523 int result;
524
525 result = qemu_peek_byte(f, 0);
526 qemu_file_skip(f, 1);
527 return result;
528 }
529
530 int64_t qemu_ftell_fast(QEMUFile *f)
531 {
532 int64_t ret = f->pos;
533 int i;
534
535 if (f->ops->writev_buffer) {
536 for (i = 0; i < f->iovcnt; i++) {
537 ret += f->iov[i].iov_len;
538 }
539 } else {
540 ret += f->buf_index;
541 }
542
543 return ret;
544 }
545
546 int64_t qemu_ftell(QEMUFile *f)
547 {
548 qemu_fflush(f);
549 return f->pos;
550 }
551
552 int qemu_file_rate_limit(QEMUFile *f)
553 {
554 if (qemu_file_get_error(f)) {
555 return 1;
556 }
557 if (f->xfer_limit > 0 && f->bytes_xfer > f->xfer_limit) {
558 return 1;
559 }
560 return 0;
561 }
562
563 int64_t qemu_file_get_rate_limit(QEMUFile *f)
564 {
565 return f->xfer_limit;
566 }
567
568 void qemu_file_set_rate_limit(QEMUFile *f, int64_t limit)
569 {
570 f->xfer_limit = limit;
571 }
572
573 void qemu_file_reset_rate_limit(QEMUFile *f)
574 {
575 f->bytes_xfer = 0;
576 }
577
578 void qemu_put_be16(QEMUFile *f, unsigned int v)
579 {
580 qemu_put_byte(f, v >> 8);
581 qemu_put_byte(f, v);
582 }
583
584 void qemu_put_be32(QEMUFile *f, unsigned int v)
585 {
586 qemu_put_byte(f, v >> 24);
587 qemu_put_byte(f, v >> 16);
588 qemu_put_byte(f, v >> 8);
589 qemu_put_byte(f, v);
590 }
591
592 void qemu_put_be64(QEMUFile *f, uint64_t v)
593 {
594 qemu_put_be32(f, v >> 32);
595 qemu_put_be32(f, v);
596 }
597
598 unsigned int qemu_get_be16(QEMUFile *f)
599 {
600 unsigned int v;
601 v = qemu_get_byte(f) << 8;
602 v |= qemu_get_byte(f);
603 return v;
604 }
605
606 unsigned int qemu_get_be32(QEMUFile *f)
607 {
608 unsigned int v;
609 v = (unsigned int)qemu_get_byte(f) << 24;
610 v |= qemu_get_byte(f) << 16;
611 v |= qemu_get_byte(f) << 8;
612 v |= qemu_get_byte(f);
613 return v;
614 }
615
616 uint64_t qemu_get_be64(QEMUFile *f)
617 {
618 uint64_t v;
619 v = (uint64_t)qemu_get_be32(f) << 32;
620 v |= qemu_get_be32(f);
621 return v;
622 }
623
624 /* compress size bytes of data start at p with specific compression
625 * level and store the compressed data to the buffer of f.
626 */
627
628 ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
629 int level)
630 {
631 ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
632
633 if (blen < compressBound(size)) {
634 return 0;
635 }
636 if (compress2(f->buf + f->buf_index + sizeof(int32_t), (uLongf *)&blen,
637 (Bytef *)p, size, level) != Z_OK) {
638 error_report("Compress Failed!");
639 return 0;
640 }
641 qemu_put_be32(f, blen);
642 f->buf_index += blen;
643 return blen + sizeof(int32_t);
644 }
645
646 /* Put the data in the buffer of f_src to the buffer of f_des, and
647 * then reset the buf_index of f_src to 0.
648 */
649
650 int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src)
651 {
652 int len = 0;
653
654 if (f_src->buf_index > 0) {
655 len = f_src->buf_index;
656 qemu_put_buffer(f_des, f_src->buf, f_src->buf_index);
657 f_src->buf_index = 0;
658 }
659 return len;
660 }
661
662 /*
663 * Get a string whose length is determined by a single preceding byte
664 * A preallocated 256 byte buffer must be passed in.
665 * Returns: len on success and a 0 terminated string in the buffer
666 * else 0
667 * (Note a 0 length string will return 0 either way)
668 */
669 size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
670 {
671 size_t len = qemu_get_byte(f);
672 size_t res = qemu_get_buffer(f, (uint8_t *)buf, len);
673
674 buf[res] = 0;
675
676 return res == len ? res : 0;
677 }
678
679 /*
680 * Set the blocking state of the QEMUFile.
681 * Note: On some transports the OS only keeps a single blocking state for
682 * both directions, and thus changing the blocking on the main
683 * QEMUFile can also affect the return path.
684 */
685 void qemu_file_set_blocking(QEMUFile *f, bool block)
686 {
687 if (f->ops->set_blocking) {
688 f->ops->set_blocking(f->opaque, block);
689 } else {
690 if (block) {
691 qemu_set_block(qemu_get_fd(f));
692 } else {
693 qemu_set_nonblock(qemu_get_fd(f));
694 }
695 }
696 }