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Commit | Line | Data |
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e4d5639d AS |
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> | |
2278a69e | 10 | * Michael Tokarev <mjt@tls.msk.ru> |
e4d5639d AS |
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. | |
6b620ca3 PB |
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. | |
e4d5639d AS |
17 | */ |
18 | ||
aafd7584 | 19 | #include "qemu/osdep.h" |
1de7afc9 | 20 | #include "qemu/iov.h" |
cc99c6f5 | 21 | #include "qemu/sockets.h" |
f348b6d1 | 22 | #include "qemu/cutils.h" |
25e5e4c7 | 23 | |
ad523bca PB |
24 | size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt, |
25 | size_t offset, const void *buf, size_t bytes) | |
e4d5639d | 26 | { |
2278a69e | 27 | size_t done; |
e4d5639d | 28 | unsigned int i; |
2278a69e MT |
29 | for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { |
30 | if (offset < iov[i].iov_len) { | |
31 | size_t len = MIN(iov[i].iov_len - offset, bytes - done); | |
32 | memcpy(iov[i].iov_base + offset, buf + done, len); | |
33 | done += len; | |
34 | offset = 0; | |
35 | } else { | |
36 | offset -= iov[i].iov_len; | |
348e7b8d | 37 | } |
e4d5639d | 38 | } |
2278a69e MT |
39 | assert(offset == 0); |
40 | return done; | |
e4d5639d | 41 | } |
fa6111f2 | 42 | |
ad523bca PB |
43 | size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, |
44 | size_t offset, void *buf, size_t bytes) | |
fa6111f2 | 45 | { |
2278a69e | 46 | size_t done; |
fa6111f2 | 47 | unsigned int i; |
2278a69e MT |
48 | for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { |
49 | if (offset < iov[i].iov_len) { | |
50 | size_t len = MIN(iov[i].iov_len - offset, bytes - done); | |
51 | memcpy(buf + done, iov[i].iov_base + offset, len); | |
52 | done += len; | |
53 | offset = 0; | |
54 | } else { | |
55 | offset -= iov[i].iov_len; | |
fa6111f2 | 56 | } |
8d15028e | 57 | } |
2278a69e MT |
58 | assert(offset == 0); |
59 | return done; | |
8d15028e GH |
60 | } |
61 | ||
dcf6f5e1 | 62 | size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, |
2278a69e | 63 | size_t offset, int fillc, size_t bytes) |
8d15028e | 64 | { |
2278a69e | 65 | size_t done; |
8d15028e | 66 | unsigned int i; |
2278a69e MT |
67 | for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { |
68 | if (offset < iov[i].iov_len) { | |
69 | size_t len = MIN(iov[i].iov_len - offset, bytes - done); | |
70 | memset(iov[i].iov_base + offset, fillc, len); | |
71 | done += len; | |
72 | offset = 0; | |
73 | } else { | |
74 | offset -= iov[i].iov_len; | |
8d15028e | 75 | } |
fa6111f2 | 76 | } |
2278a69e MT |
77 | assert(offset == 0); |
78 | return done; | |
fa6111f2 AS |
79 | } |
80 | ||
348e7b8d | 81 | size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) |
fa6111f2 AS |
82 | { |
83 | size_t len; | |
84 | unsigned int i; | |
85 | ||
86 | len = 0; | |
348e7b8d | 87 | for (i = 0; i < iov_cnt; i++) { |
fa6111f2 AS |
88 | len += iov[i].iov_len; |
89 | } | |
90 | return len; | |
91 | } | |
3a1dca94 | 92 | |
25e5e4c7 MT |
93 | /* helper function for iov_send_recv() */ |
94 | static ssize_t | |
95 | do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) | |
96 | { | |
9adea5f7 | 97 | #ifdef CONFIG_POSIX |
25e5e4c7 MT |
98 | ssize_t ret; |
99 | struct msghdr msg; | |
100 | memset(&msg, 0, sizeof(msg)); | |
101 | msg.msg_iov = iov; | |
102 | msg.msg_iovlen = iov_cnt; | |
103 | do { | |
104 | ret = do_send | |
105 | ? sendmsg(sockfd, &msg, 0) | |
106 | : recvmsg(sockfd, &msg, 0); | |
107 | } while (ret < 0 && errno == EINTR); | |
108 | return ret; | |
109 | #else | |
110 | /* else send piece-by-piece */ | |
111 | /*XXX Note: windows has WSASend() and WSARecv() */ | |
c0958559 SW |
112 | unsigned i = 0; |
113 | ssize_t ret = 0; | |
3f08376c | 114 | ssize_t off = 0; |
c0958559 | 115 | while (i < iov_cnt) { |
25e5e4c7 | 116 | ssize_t r = do_send |
3f08376c MAL |
117 | ? send(sockfd, iov[i].iov_base + off, iov[i].iov_len - off, 0) |
118 | : recv(sockfd, iov[i].iov_base + off, iov[i].iov_len - off, 0); | |
25e5e4c7 MT |
119 | if (r > 0) { |
120 | ret += r; | |
3f08376c MAL |
121 | off += r; |
122 | if (off < iov[i].iov_len) { | |
123 | continue; | |
124 | } | |
25e5e4c7 MT |
125 | } else if (!r) { |
126 | break; | |
127 | } else if (errno == EINTR) { | |
128 | continue; | |
129 | } else { | |
130 | /* else it is some "other" error, | |
131 | * only return if there was no data processed. */ | |
132 | if (ret == 0) { | |
c0958559 | 133 | ret = -1; |
25e5e4c7 MT |
134 | } |
135 | break; | |
136 | } | |
3f08376c | 137 | off = 0; |
c0958559 | 138 | i++; |
25e5e4c7 | 139 | } |
c0958559 | 140 | return ret; |
25e5e4c7 MT |
141 | #endif |
142 | } | |
143 | ||
6b64640d | 144 | ssize_t iov_send_recv(int sockfd, const struct iovec *_iov, unsigned iov_cnt, |
25e5e4c7 MT |
145 | size_t offset, size_t bytes, |
146 | bool do_send) | |
147 | { | |
83f75c26 | 148 | ssize_t total = 0; |
25e5e4c7 | 149 | ssize_t ret; |
5209d675 | 150 | size_t orig_len, tail; |
f48869ad | 151 | unsigned niov; |
6b64640d WC |
152 | struct iovec *local_iov, *iov; |
153 | ||
154 | if (bytes <= 0) { | |
155 | return 0; | |
156 | } | |
157 | ||
158 | local_iov = g_new0(struct iovec, iov_cnt); | |
159 | iov_copy(local_iov, iov_cnt, _iov, iov_cnt, offset, bytes); | |
160 | offset = 0; | |
161 | iov = local_iov; | |
5209d675 | 162 | |
83f75c26 PB |
163 | while (bytes > 0) { |
164 | /* Find the start position, skipping `offset' bytes: | |
165 | * first, skip all full-sized vector elements, */ | |
166 | for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) { | |
167 | offset -= iov[niov].iov_len; | |
168 | } | |
cb6247a7 | 169 | |
83f75c26 PB |
170 | /* niov == iov_cnt would only be valid if bytes == 0, which |
171 | * we already ruled out in the loop condition. */ | |
f48869ad | 172 | assert(niov < iov_cnt); |
83f75c26 PB |
173 | iov += niov; |
174 | iov_cnt -= niov; | |
175 | ||
176 | if (offset) { | |
177 | /* second, skip `offset' bytes from the (now) first element, | |
178 | * undo it on exit */ | |
179 | iov[0].iov_base += offset; | |
180 | iov[0].iov_len -= offset; | |
181 | } | |
182 | /* Find the end position skipping `bytes' bytes: */ | |
183 | /* first, skip all full-sized elements */ | |
184 | tail = bytes; | |
185 | for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) { | |
186 | tail -= iov[niov].iov_len; | |
187 | } | |
188 | if (tail) { | |
189 | /* second, fixup the last element, and remember the original | |
190 | * length */ | |
191 | assert(niov < iov_cnt); | |
192 | assert(iov[niov].iov_len > tail); | |
193 | orig_len = iov[niov].iov_len; | |
194 | iov[niov++].iov_len = tail; | |
2be178a4 MT |
195 | ret = do_send_recv(sockfd, iov, niov, do_send); |
196 | /* Undo the changes above before checking for errors */ | |
83f75c26 | 197 | iov[niov-1].iov_len = orig_len; |
2be178a4 MT |
198 | } else { |
199 | ret = do_send_recv(sockfd, iov, niov, do_send); | |
83f75c26 PB |
200 | } |
201 | if (offset) { | |
202 | iov[0].iov_base -= offset; | |
203 | iov[0].iov_len += offset; | |
204 | } | |
205 | ||
206 | if (ret < 0) { | |
207 | assert(errno != EINTR); | |
6b64640d | 208 | g_free(local_iov); |
83f75c26 PB |
209 | if (errno == EAGAIN && total > 0) { |
210 | return total; | |
211 | } | |
212 | return -1; | |
213 | } | |
214 | ||
84004290 MK |
215 | if (ret == 0 && !do_send) { |
216 | /* recv returns 0 when the peer has performed an orderly | |
217 | * shutdown. */ | |
218 | break; | |
219 | } | |
220 | ||
83f75c26 PB |
221 | /* Prepare for the next iteration */ |
222 | offset += ret; | |
223 | total += ret; | |
224 | bytes -= ret; | |
25e5e4c7 | 225 | } |
25e5e4c7 | 226 | |
6b64640d | 227 | g_free(local_iov); |
83f75c26 | 228 | return total; |
25e5e4c7 MT |
229 | } |
230 | ||
231 | ||
3a1dca94 GH |
232 | void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, |
233 | FILE *fp, const char *prefix, size_t limit) | |
234 | { | |
6ff66f50 PC |
235 | int v; |
236 | size_t size = 0; | |
237 | char *buf; | |
238 | ||
239 | for (v = 0; v < iov_cnt; v++) { | |
240 | size += iov[v].iov_len; | |
3a1dca94 | 241 | } |
6ff66f50 PC |
242 | size = size > limit ? limit : size; |
243 | buf = g_malloc(size); | |
244 | iov_to_buf(iov, iov_cnt, 0, buf, size); | |
b42581f5 | 245 | qemu_hexdump(fp, prefix, buf, size); |
6ff66f50 | 246 | g_free(buf); |
3a1dca94 | 247 | } |
0191253c | 248 | |
d336336c MT |
249 | unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, |
250 | const struct iovec *iov, unsigned int iov_cnt, | |
251 | size_t offset, size_t bytes) | |
252 | { | |
253 | size_t len; | |
254 | unsigned int i, j; | |
e911765c SL |
255 | for (i = 0, j = 0; |
256 | i < iov_cnt && j < dst_iov_cnt && (offset || bytes); i++) { | |
d336336c MT |
257 | if (offset >= iov[i].iov_len) { |
258 | offset -= iov[i].iov_len; | |
259 | continue; | |
260 | } | |
261 | len = MIN(bytes, iov[i].iov_len - offset); | |
262 | ||
263 | dst_iov[j].iov_base = iov[i].iov_base + offset; | |
264 | dst_iov[j].iov_len = len; | |
265 | j++; | |
266 | bytes -= len; | |
267 | offset = 0; | |
268 | } | |
269 | assert(offset == 0); | |
270 | return j; | |
271 | } | |
f563a5d7 | 272 | |
0191253c PB |
273 | /* io vectors */ |
274 | ||
275 | void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) | |
276 | { | |
e1cf5582 | 277 | qiov->iov = g_new(struct iovec, alloc_hint); |
0191253c PB |
278 | qiov->niov = 0; |
279 | qiov->nalloc = alloc_hint; | |
280 | qiov->size = 0; | |
281 | } | |
282 | ||
283 | void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) | |
284 | { | |
285 | int i; | |
286 | ||
287 | qiov->iov = iov; | |
288 | qiov->niov = niov; | |
289 | qiov->nalloc = -1; | |
290 | qiov->size = 0; | |
291 | for (i = 0; i < niov; i++) | |
292 | qiov->size += iov[i].iov_len; | |
293 | } | |
294 | ||
295 | void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) | |
296 | { | |
297 | assert(qiov->nalloc != -1); | |
298 | ||
299 | if (qiov->niov == qiov->nalloc) { | |
300 | qiov->nalloc = 2 * qiov->nalloc + 1; | |
e1cf5582 | 301 | qiov->iov = g_renew(struct iovec, qiov->iov, qiov->nalloc); |
0191253c PB |
302 | } |
303 | qiov->iov[qiov->niov].iov_base = base; | |
304 | qiov->iov[qiov->niov].iov_len = len; | |
305 | qiov->size += len; | |
306 | ++qiov->niov; | |
307 | } | |
308 | ||
309 | /* | |
530c0bbd | 310 | * Concatenates (partial) iovecs from src_iov to the end of dst. |
0191253c PB |
311 | * It starts copying after skipping `soffset' bytes at the |
312 | * beginning of src and adds individual vectors from src to | |
313 | * dst copies up to `sbytes' bytes total, or up to the end | |
530c0bbd | 314 | * of src_iov if it comes first. This way, it is okay to specify |
0191253c PB |
315 | * very large value for `sbytes' to indicate "up to the end |
316 | * of src". | |
317 | * Only vector pointers are processed, not the actual data buffers. | |
318 | */ | |
519661ee PB |
319 | size_t qemu_iovec_concat_iov(QEMUIOVector *dst, |
320 | struct iovec *src_iov, unsigned int src_cnt, | |
321 | size_t soffset, size_t sbytes) | |
0191253c PB |
322 | { |
323 | int i; | |
324 | size_t done; | |
facf98ad AK |
325 | |
326 | if (!sbytes) { | |
519661ee | 327 | return 0; |
facf98ad | 328 | } |
0191253c | 329 | assert(dst->nalloc != -1); |
530c0bbd SH |
330 | for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { |
331 | if (soffset < src_iov[i].iov_len) { | |
332 | size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); | |
333 | qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); | |
0191253c PB |
334 | done += len; |
335 | soffset = 0; | |
336 | } else { | |
530c0bbd | 337 | soffset -= src_iov[i].iov_len; |
0191253c PB |
338 | } |
339 | } | |
530c0bbd | 340 | assert(soffset == 0); /* offset beyond end of src */ |
519661ee PB |
341 | |
342 | return done; | |
530c0bbd SH |
343 | } |
344 | ||
345 | /* | |
346 | * Concatenates (partial) iovecs from src to the end of dst. | |
347 | * It starts copying after skipping `soffset' bytes at the | |
348 | * beginning of src and adds individual vectors from src to | |
349 | * dst copies up to `sbytes' bytes total, or up to the end | |
350 | * of src if it comes first. This way, it is okay to specify | |
351 | * very large value for `sbytes' to indicate "up to the end | |
352 | * of src". | |
353 | * Only vector pointers are processed, not the actual data buffers. | |
354 | */ | |
355 | void qemu_iovec_concat(QEMUIOVector *dst, | |
356 | QEMUIOVector *src, size_t soffset, size_t sbytes) | |
357 | { | |
358 | qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); | |
0191253c PB |
359 | } |
360 | ||
d953169d VSO |
361 | /* |
362 | * qiov_find_iov | |
363 | * | |
364 | * Return pointer to iovec structure, where byte at @offset in original vector | |
365 | * @iov exactly is. | |
366 | * Set @remaining_offset to be offset inside that iovec to the same byte. | |
367 | */ | |
368 | static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset, | |
369 | size_t *remaining_offset) | |
370 | { | |
371 | while (offset > 0 && offset >= iov->iov_len) { | |
372 | offset -= iov->iov_len; | |
373 | iov++; | |
374 | } | |
375 | *remaining_offset = offset; | |
376 | ||
377 | return iov; | |
378 | } | |
379 | ||
380 | /* | |
381 | * qiov_slice | |
382 | * | |
383 | * Find subarray of iovec's, containing requested range. @head would | |
384 | * be offset in first iov (returned by the function), @tail would be | |
385 | * count of extra bytes in last iovec (returned iov + @niov - 1). | |
386 | */ | |
387 | static struct iovec *qiov_slice(QEMUIOVector *qiov, | |
388 | size_t offset, size_t len, | |
389 | size_t *head, size_t *tail, int *niov) | |
390 | { | |
391 | struct iovec *iov, *end_iov; | |
392 | ||
393 | assert(offset + len <= qiov->size); | |
394 | ||
395 | iov = iov_skip_offset(qiov->iov, offset, head); | |
396 | end_iov = iov_skip_offset(iov, *head + len, tail); | |
397 | ||
398 | if (*tail > 0) { | |
399 | assert(*tail < end_iov->iov_len); | |
400 | *tail = end_iov->iov_len - *tail; | |
401 | end_iov++; | |
402 | } | |
403 | ||
404 | *niov = end_iov - iov; | |
405 | ||
406 | return iov; | |
407 | } | |
408 | ||
5396234b VSO |
409 | int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len) |
410 | { | |
411 | size_t head, tail; | |
412 | int niov; | |
413 | ||
414 | qiov_slice(qiov, offset, len, &head, &tail, &niov); | |
415 | ||
416 | return niov; | |
417 | } | |
418 | ||
d953169d VSO |
419 | /* |
420 | * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov, | |
421 | * and @tail_buf buffer into new qiov. | |
422 | */ | |
4c002cef | 423 | int qemu_iovec_init_extended( |
d953169d VSO |
424 | QEMUIOVector *qiov, |
425 | void *head_buf, size_t head_len, | |
426 | QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len, | |
427 | void *tail_buf, size_t tail_len) | |
428 | { | |
429 | size_t mid_head, mid_tail; | |
430 | int total_niov, mid_niov = 0; | |
d38d6de2 | 431 | struct iovec *p, *mid_iov = NULL; |
d953169d | 432 | |
4c002cef VSO |
433 | assert(mid_qiov->niov <= IOV_MAX); |
434 | ||
435 | if (SIZE_MAX - head_len < mid_len || | |
436 | SIZE_MAX - head_len - mid_len < tail_len) | |
437 | { | |
438 | return -EINVAL; | |
439 | } | |
440 | ||
d953169d VSO |
441 | if (mid_len) { |
442 | mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len, | |
443 | &mid_head, &mid_tail, &mid_niov); | |
444 | } | |
445 | ||
446 | total_niov = !!head_len + mid_niov + !!tail_len; | |
4c002cef VSO |
447 | if (total_niov > IOV_MAX) { |
448 | return -EINVAL; | |
449 | } | |
450 | ||
d953169d VSO |
451 | if (total_niov == 1) { |
452 | qemu_iovec_init_buf(qiov, NULL, 0); | |
453 | p = &qiov->local_iov; | |
454 | } else { | |
455 | qiov->niov = qiov->nalloc = total_niov; | |
456 | qiov->size = head_len + mid_len + tail_len; | |
457 | p = qiov->iov = g_new(struct iovec, qiov->niov); | |
458 | } | |
459 | ||
460 | if (head_len) { | |
461 | p->iov_base = head_buf; | |
462 | p->iov_len = head_len; | |
463 | p++; | |
464 | } | |
465 | ||
d38d6de2 VSO |
466 | assert(!mid_niov == !mid_len); |
467 | if (mid_niov) { | |
d953169d VSO |
468 | memcpy(p, mid_iov, mid_niov * sizeof(*p)); |
469 | p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head; | |
470 | p[0].iov_len -= mid_head; | |
471 | p[mid_niov - 1].iov_len -= mid_tail; | |
472 | p += mid_niov; | |
473 | } | |
474 | ||
475 | if (tail_len) { | |
476 | p->iov_base = tail_buf; | |
477 | p->iov_len = tail_len; | |
478 | } | |
4c002cef VSO |
479 | |
480 | return 0; | |
d953169d VSO |
481 | } |
482 | ||
43f35cb5 | 483 | /* |
f76889e7 | 484 | * Check if the contents of subrange of qiov data is all zeroes. |
43f35cb5 | 485 | */ |
f76889e7 | 486 | bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes) |
43f35cb5 | 487 | { |
f76889e7 VSO |
488 | struct iovec *iov; |
489 | size_t current_offset; | |
490 | ||
491 | assert(offset + bytes <= qiov->size); | |
492 | ||
493 | iov = iov_skip_offset(qiov->iov, offset, ¤t_offset); | |
494 | ||
495 | while (bytes) { | |
496 | uint8_t *base = (uint8_t *)iov->iov_base + current_offset; | |
497 | size_t len = MIN(iov->iov_len - current_offset, bytes); | |
498 | ||
499 | if (!buffer_is_zero(base, len)) { | |
43f35cb5 PL |
500 | return false; |
501 | } | |
f76889e7 VSO |
502 | |
503 | current_offset = 0; | |
504 | bytes -= len; | |
505 | iov++; | |
43f35cb5 | 506 | } |
f76889e7 | 507 | |
43f35cb5 PL |
508 | return true; |
509 | } | |
510 | ||
d953169d VSO |
511 | void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source, |
512 | size_t offset, size_t len) | |
513 | { | |
4c002cef VSO |
514 | int ret; |
515 | ||
516 | assert(source->size >= len); | |
517 | assert(source->size - len >= offset); | |
518 | ||
519 | /* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */ | |
520 | ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0); | |
521 | assert(ret == 0); | |
d953169d VSO |
522 | } |
523 | ||
0191253c PB |
524 | void qemu_iovec_destroy(QEMUIOVector *qiov) |
525 | { | |
d953169d VSO |
526 | if (qiov->nalloc != -1) { |
527 | g_free(qiov->iov); | |
528 | } | |
0191253c | 529 | |
d953169d | 530 | memset(qiov, 0, sizeof(*qiov)); |
0191253c PB |
531 | } |
532 | ||
533 | void qemu_iovec_reset(QEMUIOVector *qiov) | |
534 | { | |
535 | assert(qiov->nalloc != -1); | |
536 | ||
537 | qiov->niov = 0; | |
538 | qiov->size = 0; | |
539 | } | |
540 | ||
541 | size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, | |
542 | void *buf, size_t bytes) | |
543 | { | |
544 | return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); | |
545 | } | |
546 | ||
547 | size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, | |
548 | const void *buf, size_t bytes) | |
549 | { | |
550 | return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); | |
551 | } | |
552 | ||
553 | size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, | |
554 | int fillc, size_t bytes) | |
555 | { | |
556 | return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); | |
557 | } | |
d0277635 | 558 | |
f70d7f7e BC |
559 | /** |
560 | * Check that I/O vector contents are identical | |
561 | * | |
562 | * The IO vectors must have the same structure (same length of all parts). | |
563 | * A typical usage is to compare vectors created with qemu_iovec_clone(). | |
564 | * | |
565 | * @a: I/O vector | |
566 | * @b: I/O vector | |
567 | * @ret: Offset to first mismatching byte or -1 if match | |
568 | */ | |
569 | ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b) | |
570 | { | |
571 | int i; | |
572 | ssize_t offset = 0; | |
573 | ||
574 | assert(a->niov == b->niov); | |
575 | for (i = 0; i < a->niov; i++) { | |
576 | size_t len = 0; | |
577 | uint8_t *p = (uint8_t *)a->iov[i].iov_base; | |
578 | uint8_t *q = (uint8_t *)b->iov[i].iov_base; | |
579 | ||
580 | assert(a->iov[i].iov_len == b->iov[i].iov_len); | |
581 | while (len < a->iov[i].iov_len && *p++ == *q++) { | |
582 | len++; | |
583 | } | |
584 | ||
585 | offset += len; | |
586 | ||
587 | if (len != a->iov[i].iov_len) { | |
588 | return offset; | |
589 | } | |
590 | } | |
591 | return -1; | |
592 | } | |
593 | ||
594 | typedef struct { | |
595 | int src_index; | |
596 | struct iovec *src_iov; | |
597 | void *dest_base; | |
598 | } IOVectorSortElem; | |
599 | ||
600 | static int sortelem_cmp_src_base(const void *a, const void *b) | |
601 | { | |
602 | const IOVectorSortElem *elem_a = a; | |
603 | const IOVectorSortElem *elem_b = b; | |
604 | ||
605 | /* Don't overflow */ | |
606 | if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) { | |
607 | return -1; | |
608 | } else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) { | |
609 | return 1; | |
610 | } else { | |
611 | return 0; | |
612 | } | |
613 | } | |
614 | ||
615 | static int sortelem_cmp_src_index(const void *a, const void *b) | |
616 | { | |
617 | const IOVectorSortElem *elem_a = a; | |
618 | const IOVectorSortElem *elem_b = b; | |
619 | ||
620 | return elem_a->src_index - elem_b->src_index; | |
621 | } | |
622 | ||
623 | /** | |
624 | * Copy contents of I/O vector | |
625 | * | |
626 | * The relative relationships of overlapping iovecs are preserved. This is | |
627 | * necessary to ensure identical semantics in the cloned I/O vector. | |
628 | */ | |
629 | void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf) | |
630 | { | |
631 | IOVectorSortElem sortelems[src->niov]; | |
632 | void *last_end; | |
633 | int i; | |
634 | ||
635 | /* Sort by source iovecs by base address */ | |
636 | for (i = 0; i < src->niov; i++) { | |
637 | sortelems[i].src_index = i; | |
638 | sortelems[i].src_iov = &src->iov[i]; | |
639 | } | |
640 | qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base); | |
641 | ||
642 | /* Allocate buffer space taking into account overlapping iovecs */ | |
643 | last_end = NULL; | |
644 | for (i = 0; i < src->niov; i++) { | |
645 | struct iovec *cur = sortelems[i].src_iov; | |
646 | ptrdiff_t rewind = 0; | |
647 | ||
648 | /* Detect overlap */ | |
649 | if (last_end && last_end > cur->iov_base) { | |
650 | rewind = last_end - cur->iov_base; | |
651 | } | |
652 | ||
653 | sortelems[i].dest_base = buf - rewind; | |
654 | buf += cur->iov_len - MIN(rewind, cur->iov_len); | |
655 | last_end = MAX(cur->iov_base + cur->iov_len, last_end); | |
656 | } | |
657 | ||
658 | /* Sort by source iovec index and build destination iovec */ | |
659 | qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index); | |
660 | for (i = 0; i < src->niov; i++) { | |
661 | qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len); | |
662 | } | |
663 | } | |
664 | ||
9dd6f7c2 SH |
665 | void iov_discard_undo(IOVDiscardUndo *undo) |
666 | { | |
667 | /* Restore original iovec if it was modified */ | |
668 | if (undo->modified_iov) { | |
669 | *undo->modified_iov = undo->orig; | |
670 | } | |
671 | } | |
672 | ||
673 | size_t iov_discard_front_undoable(struct iovec **iov, | |
674 | unsigned int *iov_cnt, | |
675 | size_t bytes, | |
676 | IOVDiscardUndo *undo) | |
d0277635 SH |
677 | { |
678 | size_t total = 0; | |
679 | struct iovec *cur; | |
680 | ||
9dd6f7c2 SH |
681 | if (undo) { |
682 | undo->modified_iov = NULL; | |
683 | } | |
684 | ||
d0277635 SH |
685 | for (cur = *iov; *iov_cnt > 0; cur++) { |
686 | if (cur->iov_len > bytes) { | |
9dd6f7c2 SH |
687 | if (undo) { |
688 | undo->modified_iov = cur; | |
689 | undo->orig = *cur; | |
690 | } | |
691 | ||
d0277635 SH |
692 | cur->iov_base += bytes; |
693 | cur->iov_len -= bytes; | |
694 | total += bytes; | |
695 | break; | |
696 | } | |
697 | ||
698 | bytes -= cur->iov_len; | |
699 | total += cur->iov_len; | |
700 | *iov_cnt -= 1; | |
701 | } | |
702 | ||
703 | *iov = cur; | |
704 | return total; | |
705 | } | |
706 | ||
9dd6f7c2 SH |
707 | size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, |
708 | size_t bytes) | |
709 | { | |
710 | return iov_discard_front_undoable(iov, iov_cnt, bytes, NULL); | |
711 | } | |
712 | ||
713 | size_t iov_discard_back_undoable(struct iovec *iov, | |
714 | unsigned int *iov_cnt, | |
715 | size_t bytes, | |
716 | IOVDiscardUndo *undo) | |
d0277635 SH |
717 | { |
718 | size_t total = 0; | |
719 | struct iovec *cur; | |
720 | ||
9dd6f7c2 SH |
721 | if (undo) { |
722 | undo->modified_iov = NULL; | |
723 | } | |
724 | ||
d0277635 SH |
725 | if (*iov_cnt == 0) { |
726 | return 0; | |
727 | } | |
728 | ||
729 | cur = iov + (*iov_cnt - 1); | |
730 | ||
731 | while (*iov_cnt > 0) { | |
732 | if (cur->iov_len > bytes) { | |
9dd6f7c2 SH |
733 | if (undo) { |
734 | undo->modified_iov = cur; | |
735 | undo->orig = *cur; | |
736 | } | |
737 | ||
d0277635 SH |
738 | cur->iov_len -= bytes; |
739 | total += bytes; | |
740 | break; | |
741 | } | |
742 | ||
743 | bytes -= cur->iov_len; | |
744 | total += cur->iov_len; | |
745 | cur--; | |
746 | *iov_cnt -= 1; | |
747 | } | |
748 | ||
749 | return total; | |
750 | } | |
58f423fb | 751 | |
9dd6f7c2 SH |
752 | size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, |
753 | size_t bytes) | |
754 | { | |
755 | return iov_discard_back_undoable(iov, iov_cnt, bytes, NULL); | |
756 | } | |
757 | ||
58f423fb KW |
758 | void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes) |
759 | { | |
760 | size_t total; | |
761 | unsigned int niov = qiov->niov; | |
762 | ||
763 | assert(qiov->size >= bytes); | |
764 | total = iov_discard_back(qiov->iov, &niov, bytes); | |
765 | assert(total == bytes); | |
766 | ||
767 | qiov->niov = niov; | |
768 | qiov->size -= bytes; | |
769 | } |