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/error-report.h"
27#include "qemu/iov.h"
28#include "migration.h"
29#include "qemu-file.h"
30#include "trace.h"
31#include "qapi/error.h"
32
33#define IO_BUF_SIZE 32768
34#define MAX_IOV_SIZE MIN(IOV_MAX, 64)
35
36struct QEMUFile {
37 const QEMUFileOps *ops;
38 const QEMUFileHooks *hooks;
39 void *opaque;
40
41 int64_t bytes_xfer;
42 int64_t xfer_limit;
43
44 int64_t pos; /* start of buffer when writing, end of buffer
45 when reading */
46 int buf_index;
47 int buf_size; /* 0 when writing */
48 uint8_t buf[IO_BUF_SIZE];
49
50 DECLARE_BITMAP(may_free, MAX_IOV_SIZE);
51 struct iovec iov[MAX_IOV_SIZE];
52 unsigned int iovcnt;
53
54 int last_error;
55 Error *last_error_obj;
56};
57
58/*
59 * Stop a file from being read/written - not all backing files can do this
60 * typically only sockets can.
61 */
62int qemu_file_shutdown(QEMUFile *f)
63{
64 if (!f->ops->shut_down) {
65 return -ENOSYS;
66 }
67 return f->ops->shut_down(f->opaque, true, true, NULL);
68}
69
70/*
71 * Result: QEMUFile* for a 'return path' for comms in the opposite direction
72 * NULL if not available
73 */
74QEMUFile *qemu_file_get_return_path(QEMUFile *f)
75{
76 if (!f->ops->get_return_path) {
77 return NULL;
78 }
79 return f->ops->get_return_path(f->opaque);
80}
81
82bool qemu_file_mode_is_not_valid(const char *mode)
83{
84 if (mode == NULL ||
85 (mode[0] != 'r' && mode[0] != 'w') ||
86 mode[1] != 'b' || mode[2] != 0) {
87 fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
88 return true;
89 }
90
91 return false;
92}
93
94QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
95{
96 QEMUFile *f;
97
98 f = g_new0(QEMUFile, 1);
99
100 f->opaque = opaque;
101 f->ops = ops;
102 return f;
103}
104
105
106void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks)
107{
108 f->hooks = hooks;
109}
110
111/*
112 * Get last error for stream f with optional Error*
113 *
114 * Return negative error value if there has been an error on previous
115 * operations, return 0 if no error happened.
116 * Optional, it returns Error* in errp, but it may be NULL even if return value
117 * is not 0.
118 *
119 */
120int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
121{
122 if (errp) {
123 *errp = f->last_error_obj ? error_copy(f->last_error_obj) : NULL;
124 }
125 return f->last_error;
126}
127
128/*
129 * Set the last error for stream f with optional Error*
130 */
131void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err)
132{
133 if (f->last_error == 0 && ret) {
134 f->last_error = ret;
135 error_propagate(&f->last_error_obj, err);
136 } else if (err) {
137 error_report_err(err);
138 }
139}
140
141/*
142 * Get last error for stream f
143 *
144 * Return negative error value if there has been an error on previous
145 * operations, return 0 if no error happened.
146 *
147 */
148int qemu_file_get_error(QEMUFile *f)
149{
150 return qemu_file_get_error_obj(f, NULL);
151}
152
153/*
154 * Set the last error for stream f
155 */
156void qemu_file_set_error(QEMUFile *f, int ret)
157{
158 qemu_file_set_error_obj(f, ret, NULL);
159}
160
161bool qemu_file_is_writable(QEMUFile *f)
162{
163 return f->ops->writev_buffer;
164}
165
166static void qemu_iovec_release_ram(QEMUFile *f)
167{
168 struct iovec iov;
169 unsigned long idx;
170
171 /* Find and release all the contiguous memory ranges marked as may_free. */
172 idx = find_next_bit(f->may_free, f->iovcnt, 0);
173 if (idx >= f->iovcnt) {
174 return;
175 }
176 iov = f->iov[idx];
177
178 /* The madvise() in the loop is called for iov within a continuous range and
179 * then reinitialize the iov. And in the end, madvise() is called for the
180 * last iov.
181 */
182 while ((idx = find_next_bit(f->may_free, f->iovcnt, idx + 1)) < f->iovcnt) {
183 /* check for adjacent buffer and coalesce them */
184 if (iov.iov_base + iov.iov_len == f->iov[idx].iov_base) {
185 iov.iov_len += f->iov[idx].iov_len;
186 continue;
187 }
188 if (qemu_madvise(iov.iov_base, iov.iov_len, QEMU_MADV_DONTNEED) < 0) {
189 error_report("migrate: madvise DONTNEED failed %p %zd: %s",
190 iov.iov_base, iov.iov_len, strerror(errno));
191 }
192 iov = f->iov[idx];
193 }
194 if (qemu_madvise(iov.iov_base, iov.iov_len, QEMU_MADV_DONTNEED) < 0) {
195 error_report("migrate: madvise DONTNEED failed %p %zd: %s",
196 iov.iov_base, iov.iov_len, strerror(errno));
197 }
198 memset(f->may_free, 0, sizeof(f->may_free));
199}
200
201/**
202 * Flushes QEMUFile buffer
203 *
204 * If there is writev_buffer QEMUFileOps it uses it otherwise uses
205 * put_buffer ops. This will flush all pending data. If data was
206 * only partially flushed, it will set an error state.
207 */
208void qemu_fflush(QEMUFile *f)
209{
210 ssize_t ret = 0;
211 ssize_t expect = 0;
212 Error *local_error = NULL;
213
214 if (!qemu_file_is_writable(f)) {
215 return;
216 }
217
218 if (f->iovcnt > 0) {
219 expect = iov_size(f->iov, f->iovcnt);
220 ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos,
221 &local_error);
222
223 qemu_iovec_release_ram(f);
224 }
225
226 if (ret >= 0) {
227 f->pos += ret;
228 }
229 /* We expect the QEMUFile write impl to send the full
230 * data set we requested, so sanity check that.
231 */
232 if (ret != expect) {
233 qemu_file_set_error_obj(f, ret < 0 ? ret : -EIO, local_error);
234 }
235 f->buf_index = 0;
236 f->iovcnt = 0;
237}
238
239void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
240{
241 int ret = 0;
242
243 if (f->hooks && f->hooks->before_ram_iterate) {
244 ret = f->hooks->before_ram_iterate(f, f->opaque, flags, NULL);
245 if (ret < 0) {
246 qemu_file_set_error(f, ret);
247 }
248 }
249}
250
251void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
252{
253 int ret = 0;
254
255 if (f->hooks && f->hooks->after_ram_iterate) {
256 ret = f->hooks->after_ram_iterate(f, f->opaque, flags, NULL);
257 if (ret < 0) {
258 qemu_file_set_error(f, ret);
259 }
260 }
261}
262
263void ram_control_load_hook(QEMUFile *f, uint64_t flags, void *data)
264{
265 int ret = -EINVAL;
266
267 if (f->hooks && f->hooks->hook_ram_load) {
268 ret = f->hooks->hook_ram_load(f, f->opaque, flags, data);
269 if (ret < 0) {
270 qemu_file_set_error(f, ret);
271 }
272 } else {
273 /*
274 * Hook is a hook specifically requested by the source sending a flag
275 * that expects there to be a hook on the destination.
276 */
277 if (flags == RAM_CONTROL_HOOK) {
278 qemu_file_set_error(f, ret);
279 }
280 }
281}
282
283size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
284 ram_addr_t offset, size_t size,
285 uint64_t *bytes_sent)
286{
287 if (f->hooks && f->hooks->save_page) {
288 int ret = f->hooks->save_page(f, f->opaque, block_offset,
289 offset, size, bytes_sent);
290 if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
291 f->bytes_xfer += size;
292 }
293
294 if (ret != RAM_SAVE_CONTROL_DELAYED &&
295 ret != RAM_SAVE_CONTROL_NOT_SUPP) {
296 if (bytes_sent && *bytes_sent > 0) {
297 qemu_update_position(f, *bytes_sent);
298 } else if (ret < 0) {
299 qemu_file_set_error(f, ret);
300 }
301 }
302
303 return ret;
304 }
305
306 return RAM_SAVE_CONTROL_NOT_SUPP;
307}
308
309/*
310 * Attempt to fill the buffer from the underlying file
311 * Returns the number of bytes read, or negative value for an error.
312 *
313 * Note that it can return a partially full buffer even in a not error/not EOF
314 * case if the underlying file descriptor gives a short read, and that can
315 * happen even on a blocking fd.
316 */
317static ssize_t qemu_fill_buffer(QEMUFile *f)
318{
319 int len;
320 int pending;
321 Error *local_error = NULL;
322
323 assert(!qemu_file_is_writable(f));
324
325 pending = f->buf_size - f->buf_index;
326 if (pending > 0) {
327 memmove(f->buf, f->buf + f->buf_index, pending);
328 }
329 f->buf_index = 0;
330 f->buf_size = pending;
331
332 len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
333 IO_BUF_SIZE - pending, &local_error);
334 if (len > 0) {
335 f->buf_size += len;
336 f->pos += len;
337 } else if (len == 0) {
338 qemu_file_set_error_obj(f, -EIO, local_error);
339 } else if (len != -EAGAIN) {
340 qemu_file_set_error_obj(f, len, local_error);
341 } else {
342 error_free(local_error);
343 }
344
345 return len;
346}
347
348void qemu_update_position(QEMUFile *f, size_t size)
349{
350 f->pos += size;
351}
352
353/** Closes the file
354 *
355 * Returns negative error value if any error happened on previous operations or
356 * while closing the file. Returns 0 or positive number on success.
357 *
358 * The meaning of return value on success depends on the specific backend
359 * being used.
360 */
361int qemu_fclose(QEMUFile *f)
362{
363 int ret;
364 qemu_fflush(f);
365 ret = qemu_file_get_error(f);
366
367 if (f->ops->close) {
368 int ret2 = f->ops->close(f->opaque, NULL);
369 if (ret >= 0) {
370 ret = ret2;
371 }
372 }
373 /* If any error was spotted before closing, we should report it
374 * instead of the close() return value.
375 */
376 if (f->last_error) {
377 ret = f->last_error;
378 }
379 error_free(f->last_error_obj);
380 g_free(f);
381 trace_qemu_file_fclose();
382 return ret;
383}
384
385static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size,
386 bool may_free)
387{
388 /* check for adjacent buffer and coalesce them */
389 if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
390 f->iov[f->iovcnt - 1].iov_len &&
391 may_free == test_bit(f->iovcnt - 1, f->may_free))
392 {
393 f->iov[f->iovcnt - 1].iov_len += size;
394 } else {
395 if (may_free) {
396 set_bit(f->iovcnt, f->may_free);
397 }
398 f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
399 f->iov[f->iovcnt++].iov_len = size;
400 }
401
402 if (f->iovcnt >= MAX_IOV_SIZE) {
403 qemu_fflush(f);
404 }
405}
406
407void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size,
408 bool may_free)
409{
410 if (f->last_error) {
411 return;
412 }
413
414 f->bytes_xfer += size;
415 add_to_iovec(f, buf, size, may_free);
416}
417
418void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size)
419{
420 size_t l;
421
422 if (f->last_error) {
423 return;
424 }
425
426 while (size > 0) {
427 l = IO_BUF_SIZE - f->buf_index;
428 if (l > size) {
429 l = size;
430 }
431 memcpy(f->buf + f->buf_index, buf, l);
432 f->bytes_xfer += l;
433 add_to_iovec(f, f->buf + f->buf_index, l, false);
434 f->buf_index += l;
435 if (f->buf_index == IO_BUF_SIZE) {
436 qemu_fflush(f);
437 }
438 if (qemu_file_get_error(f)) {
439 break;
440 }
441 buf += l;
442 size -= l;
443 }
444}
445
446void qemu_put_byte(QEMUFile *f, int v)
447{
448 if (f->last_error) {
449 return;
450 }
451
452 f->buf[f->buf_index] = v;
453 f->bytes_xfer++;
454 add_to_iovec(f, f->buf + f->buf_index, 1, false);
455 f->buf_index++;
456 if (f->buf_index == IO_BUF_SIZE) {
457 qemu_fflush(f);
458 }
459}
460
461void qemu_file_skip(QEMUFile *f, int size)
462{
463 if (f->buf_index + size <= f->buf_size) {
464 f->buf_index += size;
465 }
466}
467
468/*
469 * Read 'size' bytes from file (at 'offset') without moving the
470 * pointer and set 'buf' to point to that data.
471 *
472 * It will return size bytes unless there was an error, in which case it will
473 * return as many as it managed to read (assuming blocking fd's which
474 * all current QEMUFile are)
475 */
476size_t qemu_peek_buffer(QEMUFile *f, uint8_t **buf, size_t size, size_t offset)
477{
478 ssize_t pending;
479 size_t index;
480
481 assert(!qemu_file_is_writable(f));
482 assert(offset < IO_BUF_SIZE);
483 assert(size <= IO_BUF_SIZE - offset);
484
485 /* The 1st byte to read from */
486 index = f->buf_index + offset;
487 /* The number of available bytes starting at index */
488 pending = f->buf_size - index;
489
490 /*
491 * qemu_fill_buffer might return just a few bytes, even when there isn't
492 * an error, so loop collecting them until we get enough.
493 */
494 while (pending < size) {
495 int received = qemu_fill_buffer(f);
496
497 if (received <= 0) {
498 break;
499 }
500
501 index = f->buf_index + offset;
502 pending = f->buf_size - index;
503 }
504
505 if (pending <= 0) {
506 return 0;
507 }
508 if (size > pending) {
509 size = pending;
510 }
511
512 *buf = f->buf + index;
513 return size;
514}
515
516/*
517 * Read 'size' bytes of data from the file into buf.
518 * 'size' can be larger than the internal buffer.
519 *
520 * It will return size bytes unless there was an error, in which case it will
521 * return as many as it managed to read (assuming blocking fd's which
522 * all current QEMUFile are)
523 */
524size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size)
525{
526 size_t pending = size;
527 size_t done = 0;
528
529 while (pending > 0) {
530 size_t res;
531 uint8_t *src;
532
533 res = qemu_peek_buffer(f, &src, MIN(pending, IO_BUF_SIZE), 0);
534 if (res == 0) {
535 return done;
536 }
537 memcpy(buf, src, res);
538 qemu_file_skip(f, res);
539 buf += res;
540 pending -= res;
541 done += res;
542 }
543 return done;
544}
545
546/*
547 * Read 'size' bytes of data from the file.
548 * 'size' can be larger than the internal buffer.
549 *
550 * The data:
551 * may be held on an internal buffer (in which case *buf is updated
552 * to point to it) that is valid until the next qemu_file operation.
553 * OR
554 * will be copied to the *buf that was passed in.
555 *
556 * The code tries to avoid the copy if possible.
557 *
558 * It will return size bytes unless there was an error, in which case it will
559 * return as many as it managed to read (assuming blocking fd's which
560 * all current QEMUFile are)
561 *
562 * Note: Since **buf may get changed, the caller should take care to
563 * keep a pointer to the original buffer if it needs to deallocate it.
564 */
565size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size)
566{
567 if (size < IO_BUF_SIZE) {
568 size_t res;
569 uint8_t *src;
570
571 res = qemu_peek_buffer(f, &src, size, 0);
572
573 if (res == size) {
574 qemu_file_skip(f, res);
575 *buf = src;
576 return res;
577 }
578 }
579
580 return qemu_get_buffer(f, *buf, size);
581}
582
583/*
584 * Peeks a single byte from the buffer; this isn't guaranteed to work if
585 * offset leaves a gap after the previous read/peeked data.
586 */
587int qemu_peek_byte(QEMUFile *f, int offset)
588{
589 int index = f->buf_index + offset;
590
591 assert(!qemu_file_is_writable(f));
592 assert(offset < IO_BUF_SIZE);
593
594 if (index >= f->buf_size) {
595 qemu_fill_buffer(f);
596 index = f->buf_index + offset;
597 if (index >= f->buf_size) {
598 return 0;
599 }
600 }
601 return f->buf[index];
602}
603
604int qemu_get_byte(QEMUFile *f)
605{
606 int result;
607
608 result = qemu_peek_byte(f, 0);
609 qemu_file_skip(f, 1);
610 return result;
611}
612
613int64_t qemu_ftell_fast(QEMUFile *f)
614{
615 int64_t ret = f->pos;
616 int i;
617
618 for (i = 0; i < f->iovcnt; i++) {
619 ret += f->iov[i].iov_len;
620 }
621
622 return ret;
623}
624
625int64_t qemu_ftell(QEMUFile *f)
626{
627 qemu_fflush(f);
628 return f->pos;
629}
630
631int qemu_file_rate_limit(QEMUFile *f)
632{
633 if (qemu_file_get_error(f)) {
634 return 1;
635 }
636 if (f->xfer_limit > 0 && f->bytes_xfer > f->xfer_limit) {
637 return 1;
638 }
639 return 0;
640}
641
642int64_t qemu_file_get_rate_limit(QEMUFile *f)
643{
644 return f->xfer_limit;
645}
646
647void qemu_file_set_rate_limit(QEMUFile *f, int64_t limit)
648{
649 f->xfer_limit = limit;
650}
651
652void qemu_file_reset_rate_limit(QEMUFile *f)
653{
654 f->bytes_xfer = 0;
655}
656
657void qemu_file_update_transfer(QEMUFile *f, int64_t len)
658{
659 f->bytes_xfer += len;
660}
661
662void qemu_put_be16(QEMUFile *f, unsigned int v)
663{
664 qemu_put_byte(f, v >> 8);
665 qemu_put_byte(f, v);
666}
667
668void qemu_put_be32(QEMUFile *f, unsigned int v)
669{
670 qemu_put_byte(f, v >> 24);
671 qemu_put_byte(f, v >> 16);
672 qemu_put_byte(f, v >> 8);
673 qemu_put_byte(f, v);
674}
675
676void qemu_put_be64(QEMUFile *f, uint64_t v)
677{
678 qemu_put_be32(f, v >> 32);
679 qemu_put_be32(f, v);
680}
681
682unsigned int qemu_get_be16(QEMUFile *f)
683{
684 unsigned int v;
685 v = qemu_get_byte(f) << 8;
686 v |= qemu_get_byte(f);
687 return v;
688}
689
690unsigned int qemu_get_be32(QEMUFile *f)
691{
692 unsigned int v;
693 v = (unsigned int)qemu_get_byte(f) << 24;
694 v |= qemu_get_byte(f) << 16;
695 v |= qemu_get_byte(f) << 8;
696 v |= qemu_get_byte(f);
697 return v;
698}
699
700uint64_t qemu_get_be64(QEMUFile *f)
701{
702 uint64_t v;
703 v = (uint64_t)qemu_get_be32(f) << 32;
704 v |= qemu_get_be32(f);
705 return v;
706}
707
708/* return the size after compression, or negative value on error */
709static int qemu_compress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
710 const uint8_t *source, size_t source_len)
711{
712 int err;
713
714 err = deflateReset(stream);
715 if (err != Z_OK) {
716 return -1;
717 }
718
719 stream->avail_in = source_len;
720 stream->next_in = (uint8_t *)source;
721 stream->avail_out = dest_len;
722 stream->next_out = dest;
723
724 err = deflate(stream, Z_FINISH);
725 if (err != Z_STREAM_END) {
726 return -1;
727 }
728
729 return stream->next_out - dest;
730}
731
732/* Compress size bytes of data start at p and store the compressed
733 * data to the buffer of f.
734 *
735 * When f is not writable, return -1 if f has no space to save the
736 * compressed data.
737 * When f is wirtable and it has no space to save the compressed data,
738 * do fflush first, if f still has no space to save the compressed
739 * data, return -1.
740 */
741ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
742 const uint8_t *p, size_t size)
743{
744 ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
745
746 if (blen < compressBound(size)) {
747 if (!qemu_file_is_writable(f)) {
748 return -1;
749 }
750 qemu_fflush(f);
751 blen = IO_BUF_SIZE - sizeof(int32_t);
752 if (blen < compressBound(size)) {
753 return -1;
754 }
755 }
756
757 blen = qemu_compress_data(stream, f->buf + f->buf_index + sizeof(int32_t),
758 blen, p, size);
759 if (blen < 0) {
760 return -1;
761 }
762
763 qemu_put_be32(f, blen);
764 if (f->ops->writev_buffer) {
765 add_to_iovec(f, f->buf + f->buf_index, blen, false);
766 }
767 f->buf_index += blen;
768 if (f->buf_index == IO_BUF_SIZE) {
769 qemu_fflush(f);
770 }
771 return blen + sizeof(int32_t);
772}
773
774/* Put the data in the buffer of f_src to the buffer of f_des, and
775 * then reset the buf_index of f_src to 0.
776 */
777
778int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src)
779{
780 int len = 0;
781
782 if (f_src->buf_index > 0) {
783 len = f_src->buf_index;
784 qemu_put_buffer(f_des, f_src->buf, f_src->buf_index);
785 f_src->buf_index = 0;
786 f_src->iovcnt = 0;
787 }
788 return len;
789}
790
791/*
792 * Get a string whose length is determined by a single preceding byte
793 * A preallocated 256 byte buffer must be passed in.
794 * Returns: len on success and a 0 terminated string in the buffer
795 * else 0
796 * (Note a 0 length string will return 0 either way)
797 */
798size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
799{
800 size_t len = qemu_get_byte(f);
801 size_t res = qemu_get_buffer(f, (uint8_t *)buf, len);
802
803 buf[res] = 0;
804
805 return res == len ? res : 0;
806}
807
808/*
809 * Put a string with one preceding byte containing its length. The length of
810 * the string should be less than 256.
811 */
812void qemu_put_counted_string(QEMUFile *f, const char *str)
813{
814 size_t len = strlen(str);
815
816 assert(len < 256);
817 qemu_put_byte(f, len);
818 qemu_put_buffer(f, (const uint8_t *)str, len);
819}
820
821/*
822 * Set the blocking state of the QEMUFile.
823 * Note: On some transports the OS only keeps a single blocking state for
824 * both directions, and thus changing the blocking on the main
825 * QEMUFile can also affect the return path.
826 */
827void qemu_file_set_blocking(QEMUFile *f, bool block)
828{
829 if (f->ops->set_blocking) {
830 f->ops->set_blocking(f->opaque, block, NULL);
831 }
832}
833