1/*
2 * Helpers for getting linearized buffers from iov / filling buffers into iovs
3 *
4 * Copyright IBM, Corp. 2007, 2008
5 * Copyright (C) 2010 Red Hat, Inc.
6 *
7 * Author(s):
8 * Anthony Liguori <aliguori@us.ibm.com>
9 * Amit Shah <amit.shah@redhat.com>
10 * Michael Tokarev <mjt@tls.msk.ru>
11 *
12 * This work is licensed under the terms of the GNU GPL, version 2. See
13 * the COPYING file in the top-level directory.
14 *
15 * Contributions after 2012-01-13 are licensed under the terms of the
16 * GNU GPL, version 2 or (at your option) any later version.
17 */
18
19#include "qemu/osdep.h"
20#include "qemu-common.h"
21#include "qemu/iov.h"
22#include "qemu/sockets.h"
23#include "qemu/cutils.h"
24
25size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
26 size_t offset, const void *buf, size_t bytes)
27{
28 size_t done;
29 unsigned int i;
30 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
31 if (offset < iov[i].iov_len) {
32 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
33 memcpy(iov[i].iov_base + offset, buf + done, len);
34 done += len;
35 offset = 0;
36 } else {
37 offset -= iov[i].iov_len;
38 }
39 }
40 assert(offset == 0);
41 return done;
42}
43
44size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
45 size_t offset, void *buf, size_t bytes)
46{
47 size_t done;
48 unsigned int i;
49 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
50 if (offset < iov[i].iov_len) {
51 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
52 memcpy(buf + done, iov[i].iov_base + offset, len);
53 done += len;
54 offset = 0;
55 } else {
56 offset -= iov[i].iov_len;
57 }
58 }
59 assert(offset == 0);
60 return done;
61}
62
63size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
64 size_t offset, int fillc, size_t bytes)
65{
66 size_t done;
67 unsigned int i;
68 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
69 if (offset < iov[i].iov_len) {
70 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
71 memset(iov[i].iov_base + offset, fillc, len);
72 done += len;
73 offset = 0;
74 } else {
75 offset -= iov[i].iov_len;
76 }
77 }
78 assert(offset == 0);
79 return done;
80}
81
82size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
83{
84 size_t len;
85 unsigned int i;
86
87 len = 0;
88 for (i = 0; i < iov_cnt; i++) {
89 len += iov[i].iov_len;
90 }
91 return len;
92}
93
94/* helper function for iov_send_recv() */
95static ssize_t
96do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send)
97{
98#ifdef CONFIG_POSIX
99 ssize_t ret;
100 struct msghdr msg;
101 memset(&msg, 0, sizeof(msg));
102 msg.msg_iov = iov;
103 msg.msg_iovlen = iov_cnt;
104 do {
105 ret = do_send
106 ? sendmsg(sockfd, &msg, 0)
107 : recvmsg(sockfd, &msg, 0);
108 } while (ret < 0 && errno == EINTR);
109 return ret;
110#else
111 /* else send piece-by-piece */
112 /*XXX Note: windows has WSASend() and WSARecv() */
113 unsigned i = 0;
114 ssize_t ret = 0;
115 while (i < iov_cnt) {
116 ssize_t r = do_send
117 ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0)
118 : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0);
119 if (r > 0) {
120 ret += r;
121 } else if (!r) {
122 break;
123 } else if (errno == EINTR) {
124 continue;
125 } else {
126 /* else it is some "other" error,
127 * only return if there was no data processed. */
128 if (ret == 0) {
129 ret = -1;
130 }
131 break;
132 }
133 i++;
134 }
135 return ret;
136#endif
137}
138
139ssize_t iov_send_recv(int sockfd, const struct iovec *_iov, unsigned iov_cnt,
140 size_t offset, size_t bytes,
141 bool do_send)
142{
143 ssize_t total = 0;
144 ssize_t ret;
145 size_t orig_len, tail;
146 unsigned niov;
147 struct iovec *local_iov, *iov;
148
149 if (bytes <= 0) {
150 return 0;
151 }
152
153 local_iov = g_new0(struct iovec, iov_cnt);
154 iov_copy(local_iov, iov_cnt, _iov, iov_cnt, offset, bytes);
155 offset = 0;
156 iov = local_iov;
157
158 while (bytes > 0) {
159 /* Find the start position, skipping `offset' bytes:
160 * first, skip all full-sized vector elements, */
161 for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) {
162 offset -= iov[niov].iov_len;
163 }
164
165 /* niov == iov_cnt would only be valid if bytes == 0, which
166 * we already ruled out in the loop condition. */
167 assert(niov < iov_cnt);
168 iov += niov;
169 iov_cnt -= niov;
170
171 if (offset) {
172 /* second, skip `offset' bytes from the (now) first element,
173 * undo it on exit */
174 iov[0].iov_base += offset;
175 iov[0].iov_len -= offset;
176 }
177 /* Find the end position skipping `bytes' bytes: */
178 /* first, skip all full-sized elements */
179 tail = bytes;
180 for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) {
181 tail -= iov[niov].iov_len;
182 }
183 if (tail) {
184 /* second, fixup the last element, and remember the original
185 * length */
186 assert(niov < iov_cnt);
187 assert(iov[niov].iov_len > tail);
188 orig_len = iov[niov].iov_len;
189 iov[niov++].iov_len = tail;
190 ret = do_send_recv(sockfd, iov, niov, do_send);
191 /* Undo the changes above before checking for errors */
192 iov[niov-1].iov_len = orig_len;
193 } else {
194 ret = do_send_recv(sockfd, iov, niov, do_send);
195 }
196 if (offset) {
197 iov[0].iov_base -= offset;
198 iov[0].iov_len += offset;
199 }
200
201 if (ret < 0) {
202 assert(errno != EINTR);
203 g_free(local_iov);
204 if (errno == EAGAIN && total > 0) {
205 return total;
206 }
207 return -1;
208 }
209
210 if (ret == 0 && !do_send) {
211 /* recv returns 0 when the peer has performed an orderly
212 * shutdown. */
213 break;
214 }
215
216 /* Prepare for the next iteration */
217 offset += ret;
218 total += ret;
219 bytes -= ret;
220 }
221
222 g_free(local_iov);
223 return total;
224}
225
226
227void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
228 FILE *fp, const char *prefix, size_t limit)
229{
230 int v;
231 size_t size = 0;
232 char *buf;
233
234 for (v = 0; v < iov_cnt; v++) {
235 size += iov[v].iov_len;
236 }
237 size = size > limit ? limit : size;
238 buf = g_malloc(size);
239 iov_to_buf(iov, iov_cnt, 0, buf, size);
240 qemu_hexdump(buf, fp, prefix, size);
241 g_free(buf);
242}
243
244unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
245 const struct iovec *iov, unsigned int iov_cnt,
246 size_t offset, size_t bytes)
247{
248 size_t len;
249 unsigned int i, j;
250 for (i = 0, j = 0;
251 i < iov_cnt && j < dst_iov_cnt && (offset || bytes); i++) {
252 if (offset >= iov[i].iov_len) {
253 offset -= iov[i].iov_len;
254 continue;
255 }
256 len = MIN(bytes, iov[i].iov_len - offset);
257
258 dst_iov[j].iov_base = iov[i].iov_base + offset;
259 dst_iov[j].iov_len = len;
260 j++;
261 bytes -= len;
262 offset = 0;
263 }
264 assert(offset == 0);
265 return j;
266}
267
268/* io vectors */
269
270void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
271{
272 qiov->iov = g_new(struct iovec, alloc_hint);
273 qiov->niov = 0;
274 qiov->nalloc = alloc_hint;
275 qiov->size = 0;
276}
277
278void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov)
279{
280 int i;
281
282 qiov->iov = iov;
283 qiov->niov = niov;
284 qiov->nalloc = -1;
285 qiov->size = 0;
286 for (i = 0; i < niov; i++)
287 qiov->size += iov[i].iov_len;
288}
289
290void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
291{
292 assert(qiov->nalloc != -1);
293
294 if (qiov->niov == qiov->nalloc) {
295 qiov->nalloc = 2 * qiov->nalloc + 1;
296 qiov->iov = g_renew(struct iovec, qiov->iov, qiov->nalloc);
297 }
298 qiov->iov[qiov->niov].iov_base = base;
299 qiov->iov[qiov->niov].iov_len = len;
300 qiov->size += len;
301 ++qiov->niov;
302}
303
304/*
305 * Concatenates (partial) iovecs from src_iov to the end of dst.
306 * It starts copying after skipping `soffset' bytes at the
307 * beginning of src and adds individual vectors from src to
308 * dst copies up to `sbytes' bytes total, or up to the end
309 * of src_iov if it comes first. This way, it is okay to specify
310 * very large value for `sbytes' to indicate "up to the end
311 * of src".
312 * Only vector pointers are processed, not the actual data buffers.
313 */
314size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
315 struct iovec *src_iov, unsigned int src_cnt,
316 size_t soffset, size_t sbytes)
317{
318 int i;
319 size_t done;
320
321 if (!sbytes) {
322 return 0;
323 }
324 assert(dst->nalloc != -1);
325 for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {
326 if (soffset < src_iov[i].iov_len) {
327 size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done);
328 qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len);
329 done += len;
330 soffset = 0;
331 } else {
332 soffset -= src_iov[i].iov_len;
333 }
334 }
335 assert(soffset == 0); /* offset beyond end of src */
336
337 return done;
338}
339
340/*
341 * Concatenates (partial) iovecs from src to the end of dst.
342 * It starts copying after skipping `soffset' bytes at the
343 * beginning of src and adds individual vectors from src to
344 * dst copies up to `sbytes' bytes total, or up to the end
345 * of src if it comes first. This way, it is okay to specify
346 * very large value for `sbytes' to indicate "up to the end
347 * of src".
348 * Only vector pointers are processed, not the actual data buffers.
349 */
350void qemu_iovec_concat(QEMUIOVector *dst,
351 QEMUIOVector *src, size_t soffset, size_t sbytes)
352{
353 qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);
354}
355
356/*
357 * qiov_find_iov
358 *
359 * Return pointer to iovec structure, where byte at @offset in original vector
360 * @iov exactly is.
361 * Set @remaining_offset to be offset inside that iovec to the same byte.
362 */
363static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset,
364 size_t *remaining_offset)
365{
366 while (offset > 0 && offset >= iov->iov_len) {
367 offset -= iov->iov_len;
368 iov++;
369 }
370 *remaining_offset = offset;
371
372 return iov;
373}
374
375/*
376 * qiov_slice
377 *
378 * Find subarray of iovec's, containing requested range. @head would
379 * be offset in first iov (returned by the function), @tail would be
380 * count of extra bytes in last iovec (returned iov + @niov - 1).
381 */
382static struct iovec *qiov_slice(QEMUIOVector *qiov,
383 size_t offset, size_t len,
384 size_t *head, size_t *tail, int *niov)
385{
386 struct iovec *iov, *end_iov;
387
388 assert(offset + len <= qiov->size);
389
390 iov = iov_skip_offset(qiov->iov, offset, head);
391 end_iov = iov_skip_offset(iov, *head + len, tail);
392
393 if (*tail > 0) {
394 assert(*tail < end_iov->iov_len);
395 *tail = end_iov->iov_len - *tail;
396 end_iov++;
397 }
398
399 *niov = end_iov - iov;
400
401 return iov;
402}
403
404int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len)
405{
406 size_t head, tail;
407 int niov;
408
409 qiov_slice(qiov, offset, len, &head, &tail, &niov);
410
411 return niov;
412}
413
414/*
415 * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov,
416 * and @tail_buf buffer into new qiov.
417 */
418void qemu_iovec_init_extended(
419 QEMUIOVector *qiov,
420 void *head_buf, size_t head_len,
421 QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
422 void *tail_buf, size_t tail_len)
423{
424 size_t mid_head, mid_tail;
425 int total_niov, mid_niov = 0;
426 struct iovec *p, *mid_iov;
427
428 if (mid_len) {
429 mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len,
430 &mid_head, &mid_tail, &mid_niov);
431 }
432
433 total_niov = !!head_len + mid_niov + !!tail_len;
434 if (total_niov == 1) {
435 qemu_iovec_init_buf(qiov, NULL, 0);
436 p = &qiov->local_iov;
437 } else {
438 qiov->niov = qiov->nalloc = total_niov;
439 qiov->size = head_len + mid_len + tail_len;
440 p = qiov->iov = g_new(struct iovec, qiov->niov);
441 }
442
443 if (head_len) {
444 p->iov_base = head_buf;
445 p->iov_len = head_len;
446 p++;
447 }
448
449 if (mid_len) {
450 memcpy(p, mid_iov, mid_niov * sizeof(*p));
451 p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head;
452 p[0].iov_len -= mid_head;
453 p[mid_niov - 1].iov_len -= mid_tail;
454 p += mid_niov;
455 }
456
457 if (tail_len) {
458 p->iov_base = tail_buf;
459 p->iov_len = tail_len;
460 }
461}
462
463/*
464 * Check if the contents of subrange of qiov data is all zeroes.
465 */
466bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes)
467{
468 struct iovec *iov;
469 size_t current_offset;
470
471 assert(offset + bytes <= qiov->size);
472
473 iov = iov_skip_offset(qiov->iov, offset, &current_offset);
474
475 while (bytes) {
476 uint8_t *base = (uint8_t *)iov->iov_base + current_offset;
477 size_t len = MIN(iov->iov_len - current_offset, bytes);
478
479 if (!buffer_is_zero(base, len)) {
480 return false;
481 }
482
483 current_offset = 0;
484 bytes -= len;
485 iov++;
486 }
487
488 return true;
489}
490
491void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
492 size_t offset, size_t len)
493{
494 qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0);
495}
496
497void qemu_iovec_destroy(QEMUIOVector *qiov)
498{
499 if (qiov->nalloc != -1) {
500 g_free(qiov->iov);
501 }
502
503 memset(qiov, 0, sizeof(*qiov));
504}
505
506void qemu_iovec_reset(QEMUIOVector *qiov)
507{
508 assert(qiov->nalloc != -1);
509
510 qiov->niov = 0;
511 qiov->size = 0;
512}
513
514size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
515 void *buf, size_t bytes)
516{
517 return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes);
518}
519
520size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
521 const void *buf, size_t bytes)
522{
523 return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes);
524}
525
526size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
527 int fillc, size_t bytes)
528{
529 return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);
530}
531
532/**
533 * Check that I/O vector contents are identical
534 *
535 * The IO vectors must have the same structure (same length of all parts).
536 * A typical usage is to compare vectors created with qemu_iovec_clone().
537 *
538 * @a: I/O vector
539 * @b: I/O vector
540 * @ret: Offset to first mismatching byte or -1 if match
541 */
542ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
543{
544 int i;
545 ssize_t offset = 0;
546
547 assert(a->niov == b->niov);
548 for (i = 0; i < a->niov; i++) {
549 size_t len = 0;
550 uint8_t *p = (uint8_t *)a->iov[i].iov_base;
551 uint8_t *q = (uint8_t *)b->iov[i].iov_base;
552
553 assert(a->iov[i].iov_len == b->iov[i].iov_len);
554 while (len < a->iov[i].iov_len && *p++ == *q++) {
555 len++;
556 }
557
558 offset += len;
559
560 if (len != a->iov[i].iov_len) {
561 return offset;
562 }
563 }
564 return -1;
565}
566
567typedef struct {
568 int src_index;
569 struct iovec *src_iov;
570 void *dest_base;
571} IOVectorSortElem;
572
573static int sortelem_cmp_src_base(const void *a, const void *b)
574{
575 const IOVectorSortElem *elem_a = a;
576 const IOVectorSortElem *elem_b = b;
577
578 /* Don't overflow */
579 if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) {
580 return -1;
581 } else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) {
582 return 1;
583 } else {
584 return 0;
585 }
586}
587
588static int sortelem_cmp_src_index(const void *a, const void *b)
589{
590 const IOVectorSortElem *elem_a = a;
591 const IOVectorSortElem *elem_b = b;
592
593 return elem_a->src_index - elem_b->src_index;
594}
595
596/**
597 * Copy contents of I/O vector
598 *
599 * The relative relationships of overlapping iovecs are preserved. This is
600 * necessary to ensure identical semantics in the cloned I/O vector.
601 */
602void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf)
603{
604 IOVectorSortElem sortelems[src->niov];
605 void *last_end;
606 int i;
607
608 /* Sort by source iovecs by base address */
609 for (i = 0; i < src->niov; i++) {
610 sortelems[i].src_index = i;
611 sortelems[i].src_iov = &src->iov[i];
612 }
613 qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base);
614
615 /* Allocate buffer space taking into account overlapping iovecs */
616 last_end = NULL;
617 for (i = 0; i < src->niov; i++) {
618 struct iovec *cur = sortelems[i].src_iov;
619 ptrdiff_t rewind = 0;
620
621 /* Detect overlap */
622 if (last_end && last_end > cur->iov_base) {
623 rewind = last_end - cur->iov_base;
624 }
625
626 sortelems[i].dest_base = buf - rewind;
627 buf += cur->iov_len - MIN(rewind, cur->iov_len);
628 last_end = MAX(cur->iov_base + cur->iov_len, last_end);
629 }
630
631 /* Sort by source iovec index and build destination iovec */
632 qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index);
633 for (i = 0; i < src->niov; i++) {
634 qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len);
635 }
636}
637
638size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt,
639 size_t bytes)
640{
641 size_t total = 0;
642 struct iovec *cur;
643
644 for (cur = *iov; *iov_cnt > 0; cur++) {
645 if (cur->iov_len > bytes) {
646 cur->iov_base += bytes;
647 cur->iov_len -= bytes;
648 total += bytes;
649 break;
650 }
651
652 bytes -= cur->iov_len;
653 total += cur->iov_len;
654 *iov_cnt -= 1;
655 }
656
657 *iov = cur;
658 return total;
659}
660
661size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
662 size_t bytes)
663{
664 size_t total = 0;
665 struct iovec *cur;
666
667 if (*iov_cnt == 0) {
668 return 0;
669 }
670
671 cur = iov + (*iov_cnt - 1);
672
673 while (*iov_cnt > 0) {
674 if (cur->iov_len > bytes) {
675 cur->iov_len -= bytes;
676 total += bytes;
677 break;
678 }
679
680 bytes -= cur->iov_len;
681 total += cur->iov_len;
682 cur--;
683 *iov_cnt -= 1;
684 }
685
686 return total;
687}
688
689void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes)
690{
691 size_t total;
692 unsigned int niov = qiov->niov;
693
694 assert(qiov->size >= bytes);
695 total = iov_discard_back(qiov->iov, &niov, bytes);
696 assert(total == bytes);
697
698 qiov->niov = niov;
699 qiov->size -= bytes;
700}
701