exec: separate sections and nodes per address space
[qemu.git] / util / iov.c
blobbb46c04e4de323eb38fe3e9ff245a5978fe9f30f
1 /*
2 * Helpers for getting linearized buffers from iov / filling buffers into iovs
4 * Copyright IBM, Corp. 2007, 2008
5 * Copyright (C) 2010 Red Hat, Inc.
7 * Author(s):
8 * Anthony Liguori <aliguori@us.ibm.com>
9 * Amit Shah <amit.shah@redhat.com>
10 * Michael Tokarev <mjt@tls.msk.ru>
12 * This work is licensed under the terms of the GNU GPL, version 2. See
13 * the COPYING file in the top-level directory.
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.
19 #include "qemu/iov.h"
21 #ifdef _WIN32
22 # include <windows.h>
23 # include <winsock2.h>
24 #else
25 # include <sys/types.h>
26 # include <sys/socket.h>
27 #endif
29 size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
30 size_t offset, const void *buf, size_t bytes)
32 size_t done;
33 unsigned int i;
34 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
35 if (offset < iov[i].iov_len) {
36 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
37 memcpy(iov[i].iov_base + offset, buf + done, len);
38 done += len;
39 offset = 0;
40 } else {
41 offset -= iov[i].iov_len;
44 assert(offset == 0);
45 return done;
48 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
49 size_t offset, void *buf, size_t bytes)
51 size_t done;
52 unsigned int i;
53 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
54 if (offset < iov[i].iov_len) {
55 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
56 memcpy(buf + done, iov[i].iov_base + offset, len);
57 done += len;
58 offset = 0;
59 } else {
60 offset -= iov[i].iov_len;
63 assert(offset == 0);
64 return done;
67 size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
68 size_t offset, int fillc, size_t bytes)
70 size_t done;
71 unsigned int i;
72 for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
73 if (offset < iov[i].iov_len) {
74 size_t len = MIN(iov[i].iov_len - offset, bytes - done);
75 memset(iov[i].iov_base + offset, fillc, len);
76 done += len;
77 offset = 0;
78 } else {
79 offset -= iov[i].iov_len;
82 assert(offset == 0);
83 return done;
86 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
88 size_t len;
89 unsigned int i;
91 len = 0;
92 for (i = 0; i < iov_cnt; i++) {
93 len += iov[i].iov_len;
95 return len;
98 /* helper function for iov_send_recv() */
99 static ssize_t
100 do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send)
102 #ifdef CONFIG_POSIX
103 ssize_t ret;
104 struct msghdr msg;
105 memset(&msg, 0, sizeof(msg));
106 msg.msg_iov = iov;
107 msg.msg_iovlen = iov_cnt;
108 do {
109 ret = do_send
110 ? sendmsg(sockfd, &msg, 0)
111 : recvmsg(sockfd, &msg, 0);
112 } while (ret < 0 && errno == EINTR);
113 return ret;
114 #else
115 /* else send piece-by-piece */
116 /*XXX Note: windows has WSASend() and WSARecv() */
117 unsigned i = 0;
118 ssize_t ret = 0;
119 while (i < iov_cnt) {
120 ssize_t r = do_send
121 ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0)
122 : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0);
123 if (r > 0) {
124 ret += r;
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) {
133 ret = -1;
135 break;
137 i++;
139 return ret;
140 #endif
143 ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
144 size_t offset, size_t bytes,
145 bool do_send)
147 ssize_t total = 0;
148 ssize_t ret;
149 size_t orig_len, tail;
150 unsigned niov;
152 while (bytes > 0) {
153 /* Find the start position, skipping `offset' bytes:
154 * first, skip all full-sized vector elements, */
155 for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) {
156 offset -= iov[niov].iov_len;
159 /* niov == iov_cnt would only be valid if bytes == 0, which
160 * we already ruled out in the loop condition. */
161 assert(niov < iov_cnt);
162 iov += niov;
163 iov_cnt -= niov;
165 if (offset) {
166 /* second, skip `offset' bytes from the (now) first element,
167 * undo it on exit */
168 iov[0].iov_base += offset;
169 iov[0].iov_len -= offset;
171 /* Find the end position skipping `bytes' bytes: */
172 /* first, skip all full-sized elements */
173 tail = bytes;
174 for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) {
175 tail -= iov[niov].iov_len;
177 if (tail) {
178 /* second, fixup the last element, and remember the original
179 * length */
180 assert(niov < iov_cnt);
181 assert(iov[niov].iov_len > tail);
182 orig_len = iov[niov].iov_len;
183 iov[niov++].iov_len = tail;
184 ret = do_send_recv(sockfd, iov, niov, do_send);
185 /* Undo the changes above before checking for errors */
186 iov[niov-1].iov_len = orig_len;
187 } else {
188 ret = do_send_recv(sockfd, iov, niov, do_send);
190 if (offset) {
191 iov[0].iov_base -= offset;
192 iov[0].iov_len += offset;
195 if (ret < 0) {
196 assert(errno != EINTR);
197 if (errno == EAGAIN && total > 0) {
198 return total;
200 return -1;
203 if (ret == 0 && !do_send) {
204 /* recv returns 0 when the peer has performed an orderly
205 * shutdown. */
206 break;
209 /* Prepare for the next iteration */
210 offset += ret;
211 total += ret;
212 bytes -= ret;
215 return total;
219 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
220 FILE *fp, const char *prefix, size_t limit)
222 int v;
223 size_t size = 0;
224 char *buf;
226 for (v = 0; v < iov_cnt; v++) {
227 size += iov[v].iov_len;
229 size = size > limit ? limit : size;
230 buf = g_malloc(size);
231 iov_to_buf(iov, iov_cnt, 0, buf, size);
232 qemu_hexdump(buf, fp, prefix, size);
233 g_free(buf);
236 unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
237 const struct iovec *iov, unsigned int iov_cnt,
238 size_t offset, size_t bytes)
240 size_t len;
241 unsigned int i, j;
242 for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) {
243 if (offset >= iov[i].iov_len) {
244 offset -= iov[i].iov_len;
245 continue;
247 len = MIN(bytes, iov[i].iov_len - offset);
249 dst_iov[j].iov_base = iov[i].iov_base + offset;
250 dst_iov[j].iov_len = len;
251 j++;
252 bytes -= len;
253 offset = 0;
255 assert(offset == 0);
256 return j;
259 /* io vectors */
261 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
263 qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec));
264 qiov->niov = 0;
265 qiov->nalloc = alloc_hint;
266 qiov->size = 0;
269 void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov)
271 int i;
273 qiov->iov = iov;
274 qiov->niov = niov;
275 qiov->nalloc = -1;
276 qiov->size = 0;
277 for (i = 0; i < niov; i++)
278 qiov->size += iov[i].iov_len;
281 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
283 assert(qiov->nalloc != -1);
285 if (qiov->niov == qiov->nalloc) {
286 qiov->nalloc = 2 * qiov->nalloc + 1;
287 qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec));
289 qiov->iov[qiov->niov].iov_base = base;
290 qiov->iov[qiov->niov].iov_len = len;
291 qiov->size += len;
292 ++qiov->niov;
296 * Concatenates (partial) iovecs from src_iov to the end of dst.
297 * It starts copying after skipping `soffset' bytes at the
298 * beginning of src and adds individual vectors from src to
299 * dst copies up to `sbytes' bytes total, or up to the end
300 * of src_iov if it comes first. This way, it is okay to specify
301 * very large value for `sbytes' to indicate "up to the end
302 * of src".
303 * Only vector pointers are processed, not the actual data buffers.
305 void qemu_iovec_concat_iov(QEMUIOVector *dst,
306 struct iovec *src_iov, unsigned int src_cnt,
307 size_t soffset, size_t sbytes)
309 int i;
310 size_t done;
312 if (!sbytes) {
313 return;
315 assert(dst->nalloc != -1);
316 for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {
317 if (soffset < src_iov[i].iov_len) {
318 size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done);
319 qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len);
320 done += len;
321 soffset = 0;
322 } else {
323 soffset -= src_iov[i].iov_len;
326 assert(soffset == 0); /* offset beyond end of src */
330 * Concatenates (partial) iovecs from src to the end of dst.
331 * It starts copying after skipping `soffset' bytes at the
332 * beginning of src and adds individual vectors from src to
333 * dst copies up to `sbytes' bytes total, or up to the end
334 * of src if it comes first. This way, it is okay to specify
335 * very large value for `sbytes' to indicate "up to the end
336 * of src".
337 * Only vector pointers are processed, not the actual data buffers.
339 void qemu_iovec_concat(QEMUIOVector *dst,
340 QEMUIOVector *src, size_t soffset, size_t sbytes)
342 qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);
345 void qemu_iovec_destroy(QEMUIOVector *qiov)
347 assert(qiov->nalloc != -1);
349 qemu_iovec_reset(qiov);
350 g_free(qiov->iov);
351 qiov->nalloc = 0;
352 qiov->iov = NULL;
355 void qemu_iovec_reset(QEMUIOVector *qiov)
357 assert(qiov->nalloc != -1);
359 qiov->niov = 0;
360 qiov->size = 0;
363 size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
364 void *buf, size_t bytes)
366 return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes);
369 size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
370 const void *buf, size_t bytes)
372 return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes);
375 size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
376 int fillc, size_t bytes)
378 return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);
381 size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt,
382 size_t bytes)
384 size_t total = 0;
385 struct iovec *cur;
387 for (cur = *iov; *iov_cnt > 0; cur++) {
388 if (cur->iov_len > bytes) {
389 cur->iov_base += bytes;
390 cur->iov_len -= bytes;
391 total += bytes;
392 break;
395 bytes -= cur->iov_len;
396 total += cur->iov_len;
397 *iov_cnt -= 1;
400 *iov = cur;
401 return total;
404 size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
405 size_t bytes)
407 size_t total = 0;
408 struct iovec *cur;
410 if (*iov_cnt == 0) {
411 return 0;
414 cur = iov + (*iov_cnt - 1);
416 while (*iov_cnt > 0) {
417 if (cur->iov_len > bytes) {
418 cur->iov_len -= bytes;
419 total += bytes;
420 break;
423 bytes -= cur->iov_len;
424 total += cur->iov_len;
425 cur--;
426 *iov_cnt -= 1;
429 return total;