1baacf047SPaolo Bonzini /* 2baacf047SPaolo Bonzini * Helpers for getting linearized buffers from iov / filling buffers into iovs 3baacf047SPaolo Bonzini * 4baacf047SPaolo Bonzini * Copyright IBM, Corp. 2007, 2008 5baacf047SPaolo Bonzini * Copyright (C) 2010 Red Hat, Inc. 6baacf047SPaolo Bonzini * 7baacf047SPaolo Bonzini * Author(s): 8baacf047SPaolo Bonzini * Anthony Liguori <aliguori@us.ibm.com> 9baacf047SPaolo Bonzini * Amit Shah <amit.shah@redhat.com> 10baacf047SPaolo Bonzini * Michael Tokarev <mjt@tls.msk.ru> 11baacf047SPaolo Bonzini * 12baacf047SPaolo Bonzini * This work is licensed under the terms of the GNU GPL, version 2. See 13baacf047SPaolo Bonzini * the COPYING file in the top-level directory. 14baacf047SPaolo Bonzini * 15baacf047SPaolo Bonzini * Contributions after 2012-01-13 are licensed under the terms of the 16baacf047SPaolo Bonzini * GNU GPL, version 2 or (at your option) any later version. 17baacf047SPaolo Bonzini */ 18baacf047SPaolo Bonzini 19aafd7584SPeter Maydell #include "qemu/osdep.h" 20baacf047SPaolo Bonzini #include "qemu/iov.h" 21cc99c6f5SStefan Weil #include "qemu/sockets.h" 22f348b6d1SVeronia Bahaa #include "qemu/cutils.h" 23baacf047SPaolo Bonzini 24ad523bcaSPaolo Bonzini size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt, 25baacf047SPaolo Bonzini size_t offset, const void *buf, size_t bytes) 26baacf047SPaolo Bonzini { 27baacf047SPaolo Bonzini size_t done; 28baacf047SPaolo Bonzini unsigned int i; 29baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 30baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 31baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 32baacf047SPaolo Bonzini memcpy(iov[i].iov_base + offset, buf + done, len); 33baacf047SPaolo Bonzini done += len; 34baacf047SPaolo Bonzini offset = 0; 35baacf047SPaolo Bonzini } else { 36baacf047SPaolo Bonzini offset -= iov[i].iov_len; 37baacf047SPaolo Bonzini } 38baacf047SPaolo Bonzini } 39baacf047SPaolo Bonzini assert(offset == 0); 40baacf047SPaolo Bonzini return done; 41baacf047SPaolo Bonzini } 42baacf047SPaolo Bonzini 43ad523bcaSPaolo Bonzini size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, 44baacf047SPaolo Bonzini size_t offset, void *buf, size_t bytes) 45baacf047SPaolo Bonzini { 46baacf047SPaolo Bonzini size_t done; 47baacf047SPaolo Bonzini unsigned int i; 48baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 49baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 50baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 51baacf047SPaolo Bonzini memcpy(buf + done, iov[i].iov_base + offset, len); 52baacf047SPaolo Bonzini done += len; 53baacf047SPaolo Bonzini offset = 0; 54baacf047SPaolo Bonzini } else { 55baacf047SPaolo Bonzini offset -= iov[i].iov_len; 56baacf047SPaolo Bonzini } 57baacf047SPaolo Bonzini } 58baacf047SPaolo Bonzini assert(offset == 0); 59baacf047SPaolo Bonzini return done; 60baacf047SPaolo Bonzini } 61baacf047SPaolo Bonzini 62baacf047SPaolo Bonzini size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, 63baacf047SPaolo Bonzini size_t offset, int fillc, size_t bytes) 64baacf047SPaolo Bonzini { 65baacf047SPaolo Bonzini size_t done; 66baacf047SPaolo Bonzini unsigned int i; 67baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 68baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 69baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 70baacf047SPaolo Bonzini memset(iov[i].iov_base + offset, fillc, len); 71baacf047SPaolo Bonzini done += len; 72baacf047SPaolo Bonzini offset = 0; 73baacf047SPaolo Bonzini } else { 74baacf047SPaolo Bonzini offset -= iov[i].iov_len; 75baacf047SPaolo Bonzini } 76baacf047SPaolo Bonzini } 77baacf047SPaolo Bonzini assert(offset == 0); 78baacf047SPaolo Bonzini return done; 79baacf047SPaolo Bonzini } 80baacf047SPaolo Bonzini 81baacf047SPaolo Bonzini size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) 82baacf047SPaolo Bonzini { 83baacf047SPaolo Bonzini size_t len; 84baacf047SPaolo Bonzini unsigned int i; 85baacf047SPaolo Bonzini 86baacf047SPaolo Bonzini len = 0; 87baacf047SPaolo Bonzini for (i = 0; i < iov_cnt; i++) { 88baacf047SPaolo Bonzini len += iov[i].iov_len; 89baacf047SPaolo Bonzini } 90baacf047SPaolo Bonzini return len; 91baacf047SPaolo Bonzini } 92baacf047SPaolo Bonzini 93baacf047SPaolo Bonzini /* helper function for iov_send_recv() */ 94baacf047SPaolo Bonzini static ssize_t 95baacf047SPaolo Bonzini do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) 96baacf047SPaolo Bonzini { 979adea5f7SPaolo Bonzini #ifdef CONFIG_POSIX 98baacf047SPaolo Bonzini ssize_t ret; 99baacf047SPaolo Bonzini struct msghdr msg; 100baacf047SPaolo Bonzini memset(&msg, 0, sizeof(msg)); 101baacf047SPaolo Bonzini msg.msg_iov = iov; 102baacf047SPaolo Bonzini msg.msg_iovlen = iov_cnt; 103baacf047SPaolo Bonzini do { 104baacf047SPaolo Bonzini ret = do_send 105baacf047SPaolo Bonzini ? sendmsg(sockfd, &msg, 0) 106baacf047SPaolo Bonzini : recvmsg(sockfd, &msg, 0); 107baacf047SPaolo Bonzini } while (ret < 0 && errno == EINTR); 108baacf047SPaolo Bonzini return ret; 109baacf047SPaolo Bonzini #else 110baacf047SPaolo Bonzini /* else send piece-by-piece */ 111baacf047SPaolo Bonzini /*XXX Note: windows has WSASend() and WSARecv() */ 112baacf047SPaolo Bonzini unsigned i = 0; 113baacf047SPaolo Bonzini ssize_t ret = 0; 114*3f08376cSMarc-André Lureau ssize_t off = 0; 115baacf047SPaolo Bonzini while (i < iov_cnt) { 116baacf047SPaolo Bonzini ssize_t r = do_send 117*3f08376cSMarc-André Lureau ? send(sockfd, iov[i].iov_base + off, iov[i].iov_len - off, 0) 118*3f08376cSMarc-André Lureau : recv(sockfd, iov[i].iov_base + off, iov[i].iov_len - off, 0); 119baacf047SPaolo Bonzini if (r > 0) { 120baacf047SPaolo Bonzini ret += r; 121*3f08376cSMarc-André Lureau off += r; 122*3f08376cSMarc-André Lureau if (off < iov[i].iov_len) { 123*3f08376cSMarc-André Lureau continue; 124*3f08376cSMarc-André Lureau } 125baacf047SPaolo Bonzini } else if (!r) { 126baacf047SPaolo Bonzini break; 127baacf047SPaolo Bonzini } else if (errno == EINTR) { 128baacf047SPaolo Bonzini continue; 129baacf047SPaolo Bonzini } else { 130baacf047SPaolo Bonzini /* else it is some "other" error, 131baacf047SPaolo Bonzini * only return if there was no data processed. */ 132baacf047SPaolo Bonzini if (ret == 0) { 133baacf047SPaolo Bonzini ret = -1; 134baacf047SPaolo Bonzini } 135baacf047SPaolo Bonzini break; 136baacf047SPaolo Bonzini } 137*3f08376cSMarc-André Lureau off = 0; 138baacf047SPaolo Bonzini i++; 139baacf047SPaolo Bonzini } 140baacf047SPaolo Bonzini return ret; 141baacf047SPaolo Bonzini #endif 142baacf047SPaolo Bonzini } 143baacf047SPaolo Bonzini 1446b64640dSWen Congyang ssize_t iov_send_recv(int sockfd, const struct iovec *_iov, unsigned iov_cnt, 145baacf047SPaolo Bonzini size_t offset, size_t bytes, 146baacf047SPaolo Bonzini bool do_send) 147baacf047SPaolo Bonzini { 14883f75c26SPaolo Bonzini ssize_t total = 0; 149baacf047SPaolo Bonzini ssize_t ret; 1505209d675SPaolo Bonzini size_t orig_len, tail; 151f48869adSPaolo Bonzini unsigned niov; 1526b64640dSWen Congyang struct iovec *local_iov, *iov; 1536b64640dSWen Congyang 1546b64640dSWen Congyang if (bytes <= 0) { 1556b64640dSWen Congyang return 0; 1566b64640dSWen Congyang } 1576b64640dSWen Congyang 1586b64640dSWen Congyang local_iov = g_new0(struct iovec, iov_cnt); 1596b64640dSWen Congyang iov_copy(local_iov, iov_cnt, _iov, iov_cnt, offset, bytes); 1606b64640dSWen Congyang offset = 0; 1616b64640dSWen Congyang iov = local_iov; 1625209d675SPaolo Bonzini 16383f75c26SPaolo Bonzini while (bytes > 0) { 164baacf047SPaolo Bonzini /* Find the start position, skipping `offset' bytes: 165baacf047SPaolo Bonzini * first, skip all full-sized vector elements, */ 166f48869adSPaolo Bonzini for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) { 167f48869adSPaolo Bonzini offset -= iov[niov].iov_len; 168baacf047SPaolo Bonzini } 169cb6247a7SPaolo Bonzini 170f48869adSPaolo Bonzini /* niov == iov_cnt would only be valid if bytes == 0, which 17183f75c26SPaolo Bonzini * we already ruled out in the loop condition. */ 172f48869adSPaolo Bonzini assert(niov < iov_cnt); 173f48869adSPaolo Bonzini iov += niov; 174f48869adSPaolo Bonzini iov_cnt -= niov; 175cb6247a7SPaolo Bonzini 176cb6247a7SPaolo Bonzini if (offset) { 177baacf047SPaolo Bonzini /* second, skip `offset' bytes from the (now) first element, 178baacf047SPaolo Bonzini * undo it on exit */ 179cb6247a7SPaolo Bonzini iov[0].iov_base += offset; 180cb6247a7SPaolo Bonzini iov[0].iov_len -= offset; 181baacf047SPaolo Bonzini } 182baacf047SPaolo Bonzini /* Find the end position skipping `bytes' bytes: */ 183baacf047SPaolo Bonzini /* first, skip all full-sized elements */ 1845209d675SPaolo Bonzini tail = bytes; 185f48869adSPaolo Bonzini for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) { 186f48869adSPaolo Bonzini tail -= iov[niov].iov_len; 187baacf047SPaolo Bonzini } 1885209d675SPaolo Bonzini if (tail) { 1895209d675SPaolo Bonzini /* second, fixup the last element, and remember the original 1905209d675SPaolo Bonzini * length */ 191f48869adSPaolo Bonzini assert(niov < iov_cnt); 192f48869adSPaolo Bonzini assert(iov[niov].iov_len > tail); 193f48869adSPaolo Bonzini orig_len = iov[niov].iov_len; 194f48869adSPaolo Bonzini iov[niov++].iov_len = tail; 195f48869adSPaolo Bonzini ret = do_send_recv(sockfd, iov, niov, do_send); 19683f75c26SPaolo Bonzini /* Undo the changes above before checking for errors */ 197f48869adSPaolo Bonzini iov[niov-1].iov_len = orig_len; 1982be178a4SMichael Tokarev } else { 1992be178a4SMichael Tokarev ret = do_send_recv(sockfd, iov, niov, do_send); 2005209d675SPaolo Bonzini } 201baacf047SPaolo Bonzini if (offset) { 202cb6247a7SPaolo Bonzini iov[0].iov_base -= offset; 203cb6247a7SPaolo Bonzini iov[0].iov_len += offset; 204baacf047SPaolo Bonzini } 205baacf047SPaolo Bonzini 20683f75c26SPaolo Bonzini if (ret < 0) { 20783f75c26SPaolo Bonzini assert(errno != EINTR); 2086b64640dSWen Congyang g_free(local_iov); 20983f75c26SPaolo Bonzini if (errno == EAGAIN && total > 0) { 21083f75c26SPaolo Bonzini return total; 21183f75c26SPaolo Bonzini } 21283f75c26SPaolo Bonzini return -1; 21383f75c26SPaolo Bonzini } 21483f75c26SPaolo Bonzini 21584004290SMORITA Kazutaka if (ret == 0 && !do_send) { 21684004290SMORITA Kazutaka /* recv returns 0 when the peer has performed an orderly 21784004290SMORITA Kazutaka * shutdown. */ 21884004290SMORITA Kazutaka break; 21984004290SMORITA Kazutaka } 22084004290SMORITA Kazutaka 22183f75c26SPaolo Bonzini /* Prepare for the next iteration */ 22283f75c26SPaolo Bonzini offset += ret; 22383f75c26SPaolo Bonzini total += ret; 22483f75c26SPaolo Bonzini bytes -= ret; 22583f75c26SPaolo Bonzini } 22683f75c26SPaolo Bonzini 2276b64640dSWen Congyang g_free(local_iov); 22883f75c26SPaolo Bonzini return total; 229baacf047SPaolo Bonzini } 230baacf047SPaolo Bonzini 231baacf047SPaolo Bonzini 232baacf047SPaolo Bonzini void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, 233baacf047SPaolo Bonzini FILE *fp, const char *prefix, size_t limit) 234baacf047SPaolo Bonzini { 2356ff66f50SPeter Crosthwaite int v; 2366ff66f50SPeter Crosthwaite size_t size = 0; 2376ff66f50SPeter Crosthwaite char *buf; 238baacf047SPaolo Bonzini 2396ff66f50SPeter Crosthwaite for (v = 0; v < iov_cnt; v++) { 2406ff66f50SPeter Crosthwaite size += iov[v].iov_len; 241baacf047SPaolo Bonzini } 2426ff66f50SPeter Crosthwaite size = size > limit ? limit : size; 2436ff66f50SPeter Crosthwaite buf = g_malloc(size); 2446ff66f50SPeter Crosthwaite iov_to_buf(iov, iov_cnt, 0, buf, size); 245b42581f5SPhilippe Mathieu-Daudé qemu_hexdump(fp, prefix, buf, size); 2466ff66f50SPeter Crosthwaite g_free(buf); 247baacf047SPaolo Bonzini } 248baacf047SPaolo Bonzini 249baacf047SPaolo Bonzini unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, 250baacf047SPaolo Bonzini const struct iovec *iov, unsigned int iov_cnt, 251baacf047SPaolo Bonzini size_t offset, size_t bytes) 252baacf047SPaolo Bonzini { 253baacf047SPaolo Bonzini size_t len; 254baacf047SPaolo Bonzini unsigned int i, j; 255e911765cSShmulik Ladkani for (i = 0, j = 0; 256e911765cSShmulik Ladkani i < iov_cnt && j < dst_iov_cnt && (offset || bytes); i++) { 257baacf047SPaolo Bonzini if (offset >= iov[i].iov_len) { 258baacf047SPaolo Bonzini offset -= iov[i].iov_len; 259baacf047SPaolo Bonzini continue; 260baacf047SPaolo Bonzini } 261baacf047SPaolo Bonzini len = MIN(bytes, iov[i].iov_len - offset); 262baacf047SPaolo Bonzini 263baacf047SPaolo Bonzini dst_iov[j].iov_base = iov[i].iov_base + offset; 264baacf047SPaolo Bonzini dst_iov[j].iov_len = len; 265baacf047SPaolo Bonzini j++; 266baacf047SPaolo Bonzini bytes -= len; 267baacf047SPaolo Bonzini offset = 0; 268baacf047SPaolo Bonzini } 269baacf047SPaolo Bonzini assert(offset == 0); 270baacf047SPaolo Bonzini return j; 271baacf047SPaolo Bonzini } 272baacf047SPaolo Bonzini 273baacf047SPaolo Bonzini /* io vectors */ 274baacf047SPaolo Bonzini 275baacf047SPaolo Bonzini void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) 276baacf047SPaolo Bonzini { 277e1cf5582SMarkus Armbruster qiov->iov = g_new(struct iovec, alloc_hint); 278baacf047SPaolo Bonzini qiov->niov = 0; 279baacf047SPaolo Bonzini qiov->nalloc = alloc_hint; 280baacf047SPaolo Bonzini qiov->size = 0; 281baacf047SPaolo Bonzini } 282baacf047SPaolo Bonzini 283baacf047SPaolo Bonzini void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) 284baacf047SPaolo Bonzini { 285baacf047SPaolo Bonzini int i; 286baacf047SPaolo Bonzini 287baacf047SPaolo Bonzini qiov->iov = iov; 288baacf047SPaolo Bonzini qiov->niov = niov; 289baacf047SPaolo Bonzini qiov->nalloc = -1; 290baacf047SPaolo Bonzini qiov->size = 0; 291baacf047SPaolo Bonzini for (i = 0; i < niov; i++) 292baacf047SPaolo Bonzini qiov->size += iov[i].iov_len; 293baacf047SPaolo Bonzini } 294baacf047SPaolo Bonzini 295baacf047SPaolo Bonzini void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) 296baacf047SPaolo Bonzini { 297baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 298baacf047SPaolo Bonzini 299baacf047SPaolo Bonzini if (qiov->niov == qiov->nalloc) { 300baacf047SPaolo Bonzini qiov->nalloc = 2 * qiov->nalloc + 1; 301e1cf5582SMarkus Armbruster qiov->iov = g_renew(struct iovec, qiov->iov, qiov->nalloc); 302baacf047SPaolo Bonzini } 303baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_base = base; 304baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_len = len; 305baacf047SPaolo Bonzini qiov->size += len; 306baacf047SPaolo Bonzini ++qiov->niov; 307baacf047SPaolo Bonzini } 308baacf047SPaolo Bonzini 309baacf047SPaolo Bonzini /* 310baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src_iov to the end of dst. 311baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 312baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 313baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 314baacf047SPaolo Bonzini * of src_iov if it comes first. This way, it is okay to specify 315baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 316baacf047SPaolo Bonzini * of src". 317baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 318baacf047SPaolo Bonzini */ 319519661eeSPaolo Bonzini size_t qemu_iovec_concat_iov(QEMUIOVector *dst, 320baacf047SPaolo Bonzini struct iovec *src_iov, unsigned int src_cnt, 321baacf047SPaolo Bonzini size_t soffset, size_t sbytes) 322baacf047SPaolo Bonzini { 323baacf047SPaolo Bonzini int i; 324baacf047SPaolo Bonzini size_t done; 325facf98adSAneesh Kumar K.V 326facf98adSAneesh Kumar K.V if (!sbytes) { 327519661eeSPaolo Bonzini return 0; 328facf98adSAneesh Kumar K.V } 329baacf047SPaolo Bonzini assert(dst->nalloc != -1); 330baacf047SPaolo Bonzini for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { 331baacf047SPaolo Bonzini if (soffset < src_iov[i].iov_len) { 332baacf047SPaolo Bonzini size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); 333baacf047SPaolo Bonzini qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); 334baacf047SPaolo Bonzini done += len; 335baacf047SPaolo Bonzini soffset = 0; 336baacf047SPaolo Bonzini } else { 337baacf047SPaolo Bonzini soffset -= src_iov[i].iov_len; 338baacf047SPaolo Bonzini } 339baacf047SPaolo Bonzini } 340baacf047SPaolo Bonzini assert(soffset == 0); /* offset beyond end of src */ 341519661eeSPaolo Bonzini 342519661eeSPaolo Bonzini return done; 343baacf047SPaolo Bonzini } 344baacf047SPaolo Bonzini 345baacf047SPaolo Bonzini /* 346baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src to the end of dst. 347baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 348baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 349baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 350baacf047SPaolo Bonzini * of src if it comes first. This way, it is okay to specify 351baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 352baacf047SPaolo Bonzini * of src". 353baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 354baacf047SPaolo Bonzini */ 355baacf047SPaolo Bonzini void qemu_iovec_concat(QEMUIOVector *dst, 356baacf047SPaolo Bonzini QEMUIOVector *src, size_t soffset, size_t sbytes) 357baacf047SPaolo Bonzini { 358baacf047SPaolo Bonzini qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); 359baacf047SPaolo Bonzini } 360baacf047SPaolo Bonzini 36143f35cb5SPeter Lieven /* 362d953169dSVladimir Sementsov-Ogievskiy * qiov_find_iov 363d953169dSVladimir Sementsov-Ogievskiy * 364d953169dSVladimir Sementsov-Ogievskiy * Return pointer to iovec structure, where byte at @offset in original vector 365d953169dSVladimir Sementsov-Ogievskiy * @iov exactly is. 366d953169dSVladimir Sementsov-Ogievskiy * Set @remaining_offset to be offset inside that iovec to the same byte. 367d953169dSVladimir Sementsov-Ogievskiy */ 368d953169dSVladimir Sementsov-Ogievskiy static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset, 369d953169dSVladimir Sementsov-Ogievskiy size_t *remaining_offset) 370d953169dSVladimir Sementsov-Ogievskiy { 371d953169dSVladimir Sementsov-Ogievskiy while (offset > 0 && offset >= iov->iov_len) { 372d953169dSVladimir Sementsov-Ogievskiy offset -= iov->iov_len; 373d953169dSVladimir Sementsov-Ogievskiy iov++; 374d953169dSVladimir Sementsov-Ogievskiy } 375d953169dSVladimir Sementsov-Ogievskiy *remaining_offset = offset; 376d953169dSVladimir Sementsov-Ogievskiy 377d953169dSVladimir Sementsov-Ogievskiy return iov; 378d953169dSVladimir Sementsov-Ogievskiy } 379d953169dSVladimir Sementsov-Ogievskiy 380d953169dSVladimir Sementsov-Ogievskiy /* 381d953169dSVladimir Sementsov-Ogievskiy * qiov_slice 382d953169dSVladimir Sementsov-Ogievskiy * 383d953169dSVladimir Sementsov-Ogievskiy * Find subarray of iovec's, containing requested range. @head would 384d953169dSVladimir Sementsov-Ogievskiy * be offset in first iov (returned by the function), @tail would be 385d953169dSVladimir Sementsov-Ogievskiy * count of extra bytes in last iovec (returned iov + @niov - 1). 386d953169dSVladimir Sementsov-Ogievskiy */ 387d953169dSVladimir Sementsov-Ogievskiy static struct iovec *qiov_slice(QEMUIOVector *qiov, 388d953169dSVladimir Sementsov-Ogievskiy size_t offset, size_t len, 389d953169dSVladimir Sementsov-Ogievskiy size_t *head, size_t *tail, int *niov) 390d953169dSVladimir Sementsov-Ogievskiy { 391d953169dSVladimir Sementsov-Ogievskiy struct iovec *iov, *end_iov; 392d953169dSVladimir Sementsov-Ogievskiy 393d953169dSVladimir Sementsov-Ogievskiy assert(offset + len <= qiov->size); 394d953169dSVladimir Sementsov-Ogievskiy 395d953169dSVladimir Sementsov-Ogievskiy iov = iov_skip_offset(qiov->iov, offset, head); 396d953169dSVladimir Sementsov-Ogievskiy end_iov = iov_skip_offset(iov, *head + len, tail); 397d953169dSVladimir Sementsov-Ogievskiy 398d953169dSVladimir Sementsov-Ogievskiy if (*tail > 0) { 399d953169dSVladimir Sementsov-Ogievskiy assert(*tail < end_iov->iov_len); 400d953169dSVladimir Sementsov-Ogievskiy *tail = end_iov->iov_len - *tail; 401d953169dSVladimir Sementsov-Ogievskiy end_iov++; 402d953169dSVladimir Sementsov-Ogievskiy } 403d953169dSVladimir Sementsov-Ogievskiy 404d953169dSVladimir Sementsov-Ogievskiy *niov = end_iov - iov; 405d953169dSVladimir Sementsov-Ogievskiy 406d953169dSVladimir Sementsov-Ogievskiy return iov; 407d953169dSVladimir Sementsov-Ogievskiy } 408d953169dSVladimir Sementsov-Ogievskiy 4095396234bSVladimir Sementsov-Ogievskiy int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len) 4105396234bSVladimir Sementsov-Ogievskiy { 4115396234bSVladimir Sementsov-Ogievskiy size_t head, tail; 4125396234bSVladimir Sementsov-Ogievskiy int niov; 4135396234bSVladimir Sementsov-Ogievskiy 4145396234bSVladimir Sementsov-Ogievskiy qiov_slice(qiov, offset, len, &head, &tail, &niov); 4155396234bSVladimir Sementsov-Ogievskiy 4165396234bSVladimir Sementsov-Ogievskiy return niov; 4175396234bSVladimir Sementsov-Ogievskiy } 4185396234bSVladimir Sementsov-Ogievskiy 419d953169dSVladimir Sementsov-Ogievskiy /* 420d953169dSVladimir Sementsov-Ogievskiy * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov, 421d953169dSVladimir Sementsov-Ogievskiy * and @tail_buf buffer into new qiov. 422d953169dSVladimir Sementsov-Ogievskiy */ 4234c002cefSVladimir Sementsov-Ogievskiy int qemu_iovec_init_extended( 424d953169dSVladimir Sementsov-Ogievskiy QEMUIOVector *qiov, 425d953169dSVladimir Sementsov-Ogievskiy void *head_buf, size_t head_len, 426d953169dSVladimir Sementsov-Ogievskiy QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len, 427d953169dSVladimir Sementsov-Ogievskiy void *tail_buf, size_t tail_len) 428d953169dSVladimir Sementsov-Ogievskiy { 429d953169dSVladimir Sementsov-Ogievskiy size_t mid_head, mid_tail; 430d953169dSVladimir Sementsov-Ogievskiy int total_niov, mid_niov = 0; 431d38d6de2SVladimir Sementsov-Ogievskiy struct iovec *p, *mid_iov = NULL; 432d953169dSVladimir Sementsov-Ogievskiy 4334c002cefSVladimir Sementsov-Ogievskiy assert(mid_qiov->niov <= IOV_MAX); 4344c002cefSVladimir Sementsov-Ogievskiy 4354c002cefSVladimir Sementsov-Ogievskiy if (SIZE_MAX - head_len < mid_len || 4364c002cefSVladimir Sementsov-Ogievskiy SIZE_MAX - head_len - mid_len < tail_len) 4374c002cefSVladimir Sementsov-Ogievskiy { 4384c002cefSVladimir Sementsov-Ogievskiy return -EINVAL; 4394c002cefSVladimir Sementsov-Ogievskiy } 4404c002cefSVladimir Sementsov-Ogievskiy 441d953169dSVladimir Sementsov-Ogievskiy if (mid_len) { 442d953169dSVladimir Sementsov-Ogievskiy mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len, 443d953169dSVladimir Sementsov-Ogievskiy &mid_head, &mid_tail, &mid_niov); 444d953169dSVladimir Sementsov-Ogievskiy } 445d953169dSVladimir Sementsov-Ogievskiy 446d953169dSVladimir Sementsov-Ogievskiy total_niov = !!head_len + mid_niov + !!tail_len; 4474c002cefSVladimir Sementsov-Ogievskiy if (total_niov > IOV_MAX) { 4484c002cefSVladimir Sementsov-Ogievskiy return -EINVAL; 4494c002cefSVladimir Sementsov-Ogievskiy } 4504c002cefSVladimir Sementsov-Ogievskiy 451d953169dSVladimir Sementsov-Ogievskiy if (total_niov == 1) { 452d953169dSVladimir Sementsov-Ogievskiy qemu_iovec_init_buf(qiov, NULL, 0); 453d953169dSVladimir Sementsov-Ogievskiy p = &qiov->local_iov; 454d953169dSVladimir Sementsov-Ogievskiy } else { 455d953169dSVladimir Sementsov-Ogievskiy qiov->niov = qiov->nalloc = total_niov; 456d953169dSVladimir Sementsov-Ogievskiy qiov->size = head_len + mid_len + tail_len; 457d953169dSVladimir Sementsov-Ogievskiy p = qiov->iov = g_new(struct iovec, qiov->niov); 458d953169dSVladimir Sementsov-Ogievskiy } 459d953169dSVladimir Sementsov-Ogievskiy 460d953169dSVladimir Sementsov-Ogievskiy if (head_len) { 461d953169dSVladimir Sementsov-Ogievskiy p->iov_base = head_buf; 462d953169dSVladimir Sementsov-Ogievskiy p->iov_len = head_len; 463d953169dSVladimir Sementsov-Ogievskiy p++; 464d953169dSVladimir Sementsov-Ogievskiy } 465d953169dSVladimir Sementsov-Ogievskiy 466d38d6de2SVladimir Sementsov-Ogievskiy assert(!mid_niov == !mid_len); 467d38d6de2SVladimir Sementsov-Ogievskiy if (mid_niov) { 468d953169dSVladimir Sementsov-Ogievskiy memcpy(p, mid_iov, mid_niov * sizeof(*p)); 469d953169dSVladimir Sementsov-Ogievskiy p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head; 470d953169dSVladimir Sementsov-Ogievskiy p[0].iov_len -= mid_head; 471d953169dSVladimir Sementsov-Ogievskiy p[mid_niov - 1].iov_len -= mid_tail; 472d953169dSVladimir Sementsov-Ogievskiy p += mid_niov; 473d953169dSVladimir Sementsov-Ogievskiy } 474d953169dSVladimir Sementsov-Ogievskiy 475d953169dSVladimir Sementsov-Ogievskiy if (tail_len) { 476d953169dSVladimir Sementsov-Ogievskiy p->iov_base = tail_buf; 477d953169dSVladimir Sementsov-Ogievskiy p->iov_len = tail_len; 478d953169dSVladimir Sementsov-Ogievskiy } 4794c002cefSVladimir Sementsov-Ogievskiy 4804c002cefSVladimir Sementsov-Ogievskiy return 0; 481d953169dSVladimir Sementsov-Ogievskiy } 482d953169dSVladimir Sementsov-Ogievskiy 483d953169dSVladimir Sementsov-Ogievskiy /* 484f76889e7SVladimir Sementsov-Ogievskiy * Check if the contents of subrange of qiov data is all zeroes. 48543f35cb5SPeter Lieven */ 486f76889e7SVladimir Sementsov-Ogievskiy bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes) 48743f35cb5SPeter Lieven { 488f76889e7SVladimir Sementsov-Ogievskiy struct iovec *iov; 489f76889e7SVladimir Sementsov-Ogievskiy size_t current_offset; 490f76889e7SVladimir Sementsov-Ogievskiy 491f76889e7SVladimir Sementsov-Ogievskiy assert(offset + bytes <= qiov->size); 492f76889e7SVladimir Sementsov-Ogievskiy 493f76889e7SVladimir Sementsov-Ogievskiy iov = iov_skip_offset(qiov->iov, offset, ¤t_offset); 494f76889e7SVladimir Sementsov-Ogievskiy 495f76889e7SVladimir Sementsov-Ogievskiy while (bytes) { 496f76889e7SVladimir Sementsov-Ogievskiy uint8_t *base = (uint8_t *)iov->iov_base + current_offset; 497f76889e7SVladimir Sementsov-Ogievskiy size_t len = MIN(iov->iov_len - current_offset, bytes); 498f76889e7SVladimir Sementsov-Ogievskiy 499f76889e7SVladimir Sementsov-Ogievskiy if (!buffer_is_zero(base, len)) { 50043f35cb5SPeter Lieven return false; 50143f35cb5SPeter Lieven } 502f76889e7SVladimir Sementsov-Ogievskiy 503f76889e7SVladimir Sementsov-Ogievskiy current_offset = 0; 504f76889e7SVladimir Sementsov-Ogievskiy bytes -= len; 505f76889e7SVladimir Sementsov-Ogievskiy iov++; 50643f35cb5SPeter Lieven } 507f76889e7SVladimir Sementsov-Ogievskiy 50843f35cb5SPeter Lieven return true; 50943f35cb5SPeter Lieven } 51043f35cb5SPeter Lieven 511d953169dSVladimir Sementsov-Ogievskiy void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source, 512d953169dSVladimir Sementsov-Ogievskiy size_t offset, size_t len) 513d953169dSVladimir Sementsov-Ogievskiy { 5144c002cefSVladimir Sementsov-Ogievskiy int ret; 5154c002cefSVladimir Sementsov-Ogievskiy 5164c002cefSVladimir Sementsov-Ogievskiy assert(source->size >= len); 5174c002cefSVladimir Sementsov-Ogievskiy assert(source->size - len >= offset); 5184c002cefSVladimir Sementsov-Ogievskiy 5194c002cefSVladimir Sementsov-Ogievskiy /* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */ 5204c002cefSVladimir Sementsov-Ogievskiy ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0); 5214c002cefSVladimir Sementsov-Ogievskiy assert(ret == 0); 522d953169dSVladimir Sementsov-Ogievskiy } 523d953169dSVladimir Sementsov-Ogievskiy 524baacf047SPaolo Bonzini void qemu_iovec_destroy(QEMUIOVector *qiov) 525baacf047SPaolo Bonzini { 526d953169dSVladimir Sementsov-Ogievskiy if (qiov->nalloc != -1) { 527baacf047SPaolo Bonzini g_free(qiov->iov); 528d953169dSVladimir Sementsov-Ogievskiy } 529d953169dSVladimir Sementsov-Ogievskiy 530d953169dSVladimir Sementsov-Ogievskiy memset(qiov, 0, sizeof(*qiov)); 531baacf047SPaolo Bonzini } 532baacf047SPaolo Bonzini 533baacf047SPaolo Bonzini void qemu_iovec_reset(QEMUIOVector *qiov) 534baacf047SPaolo Bonzini { 535baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 536baacf047SPaolo Bonzini 537baacf047SPaolo Bonzini qiov->niov = 0; 538baacf047SPaolo Bonzini qiov->size = 0; 539baacf047SPaolo Bonzini } 540baacf047SPaolo Bonzini 541baacf047SPaolo Bonzini size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, 542baacf047SPaolo Bonzini void *buf, size_t bytes) 543baacf047SPaolo Bonzini { 544baacf047SPaolo Bonzini return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); 545baacf047SPaolo Bonzini } 546baacf047SPaolo Bonzini 547baacf047SPaolo Bonzini size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, 548baacf047SPaolo Bonzini const void *buf, size_t bytes) 549baacf047SPaolo Bonzini { 550baacf047SPaolo Bonzini return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); 551baacf047SPaolo Bonzini } 552baacf047SPaolo Bonzini 553baacf047SPaolo Bonzini size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, 554baacf047SPaolo Bonzini int fillc, size_t bytes) 555baacf047SPaolo Bonzini { 556baacf047SPaolo Bonzini return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); 557baacf047SPaolo Bonzini } 558baacf047SPaolo Bonzini 559f70d7f7eSBenoît Canet /** 560f70d7f7eSBenoît Canet * Check that I/O vector contents are identical 561f70d7f7eSBenoît Canet * 562f70d7f7eSBenoît Canet * The IO vectors must have the same structure (same length of all parts). 563f70d7f7eSBenoît Canet * A typical usage is to compare vectors created with qemu_iovec_clone(). 564f70d7f7eSBenoît Canet * 565f70d7f7eSBenoît Canet * @a: I/O vector 566f70d7f7eSBenoît Canet * @b: I/O vector 567f70d7f7eSBenoît Canet * @ret: Offset to first mismatching byte or -1 if match 568f70d7f7eSBenoît Canet */ 569f70d7f7eSBenoît Canet ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b) 570f70d7f7eSBenoît Canet { 571f70d7f7eSBenoît Canet int i; 572f70d7f7eSBenoît Canet ssize_t offset = 0; 573f70d7f7eSBenoît Canet 574f70d7f7eSBenoît Canet assert(a->niov == b->niov); 575f70d7f7eSBenoît Canet for (i = 0; i < a->niov; i++) { 576f70d7f7eSBenoît Canet size_t len = 0; 577f70d7f7eSBenoît Canet uint8_t *p = (uint8_t *)a->iov[i].iov_base; 578f70d7f7eSBenoît Canet uint8_t *q = (uint8_t *)b->iov[i].iov_base; 579f70d7f7eSBenoît Canet 580f70d7f7eSBenoît Canet assert(a->iov[i].iov_len == b->iov[i].iov_len); 581f70d7f7eSBenoît Canet while (len < a->iov[i].iov_len && *p++ == *q++) { 582f70d7f7eSBenoît Canet len++; 583f70d7f7eSBenoît Canet } 584f70d7f7eSBenoît Canet 585f70d7f7eSBenoît Canet offset += len; 586f70d7f7eSBenoît Canet 587f70d7f7eSBenoît Canet if (len != a->iov[i].iov_len) { 588f70d7f7eSBenoît Canet return offset; 589f70d7f7eSBenoît Canet } 590f70d7f7eSBenoît Canet } 591f70d7f7eSBenoît Canet return -1; 592f70d7f7eSBenoît Canet } 593f70d7f7eSBenoît Canet 594f70d7f7eSBenoît Canet typedef struct { 595f70d7f7eSBenoît Canet int src_index; 596f70d7f7eSBenoît Canet struct iovec *src_iov; 597f70d7f7eSBenoît Canet void *dest_base; 598f70d7f7eSBenoît Canet } IOVectorSortElem; 599f70d7f7eSBenoît Canet 600f70d7f7eSBenoît Canet static int sortelem_cmp_src_base(const void *a, const void *b) 601f70d7f7eSBenoît Canet { 602f70d7f7eSBenoît Canet const IOVectorSortElem *elem_a = a; 603f70d7f7eSBenoît Canet const IOVectorSortElem *elem_b = b; 604f70d7f7eSBenoît Canet 605f70d7f7eSBenoît Canet /* Don't overflow */ 606f70d7f7eSBenoît Canet if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) { 607f70d7f7eSBenoît Canet return -1; 608f70d7f7eSBenoît Canet } else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) { 609f70d7f7eSBenoît Canet return 1; 610f70d7f7eSBenoît Canet } else { 611f70d7f7eSBenoît Canet return 0; 612f70d7f7eSBenoît Canet } 613f70d7f7eSBenoît Canet } 614f70d7f7eSBenoît Canet 615f70d7f7eSBenoît Canet static int sortelem_cmp_src_index(const void *a, const void *b) 616f70d7f7eSBenoît Canet { 617f70d7f7eSBenoît Canet const IOVectorSortElem *elem_a = a; 618f70d7f7eSBenoît Canet const IOVectorSortElem *elem_b = b; 619f70d7f7eSBenoît Canet 620f70d7f7eSBenoît Canet return elem_a->src_index - elem_b->src_index; 621f70d7f7eSBenoît Canet } 622f70d7f7eSBenoît Canet 623f70d7f7eSBenoît Canet /** 624f70d7f7eSBenoît Canet * Copy contents of I/O vector 625f70d7f7eSBenoît Canet * 626f70d7f7eSBenoît Canet * The relative relationships of overlapping iovecs are preserved. This is 627f70d7f7eSBenoît Canet * necessary to ensure identical semantics in the cloned I/O vector. 628f70d7f7eSBenoît Canet */ 629f70d7f7eSBenoît Canet void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf) 630f70d7f7eSBenoît Canet { 631f70d7f7eSBenoît Canet IOVectorSortElem sortelems[src->niov]; 632f70d7f7eSBenoît Canet void *last_end; 633f70d7f7eSBenoît Canet int i; 634f70d7f7eSBenoît Canet 635f70d7f7eSBenoît Canet /* Sort by source iovecs by base address */ 636f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 637f70d7f7eSBenoît Canet sortelems[i].src_index = i; 638f70d7f7eSBenoît Canet sortelems[i].src_iov = &src->iov[i]; 639f70d7f7eSBenoît Canet } 640f70d7f7eSBenoît Canet qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base); 641f70d7f7eSBenoît Canet 642f70d7f7eSBenoît Canet /* Allocate buffer space taking into account overlapping iovecs */ 643f70d7f7eSBenoît Canet last_end = NULL; 644f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 645f70d7f7eSBenoît Canet struct iovec *cur = sortelems[i].src_iov; 646f70d7f7eSBenoît Canet ptrdiff_t rewind = 0; 647f70d7f7eSBenoît Canet 648f70d7f7eSBenoît Canet /* Detect overlap */ 649f70d7f7eSBenoît Canet if (last_end && last_end > cur->iov_base) { 650f70d7f7eSBenoît Canet rewind = last_end - cur->iov_base; 651f70d7f7eSBenoît Canet } 652f70d7f7eSBenoît Canet 653f70d7f7eSBenoît Canet sortelems[i].dest_base = buf - rewind; 654f70d7f7eSBenoît Canet buf += cur->iov_len - MIN(rewind, cur->iov_len); 655f70d7f7eSBenoît Canet last_end = MAX(cur->iov_base + cur->iov_len, last_end); 656f70d7f7eSBenoît Canet } 657f70d7f7eSBenoît Canet 658f70d7f7eSBenoît Canet /* Sort by source iovec index and build destination iovec */ 659f70d7f7eSBenoît Canet qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index); 660f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 661f70d7f7eSBenoît Canet qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len); 662f70d7f7eSBenoît Canet } 663f70d7f7eSBenoît Canet } 664f70d7f7eSBenoît Canet 6659dd6f7c2SStefan Hajnoczi void iov_discard_undo(IOVDiscardUndo *undo) 6669dd6f7c2SStefan Hajnoczi { 6679dd6f7c2SStefan Hajnoczi /* Restore original iovec if it was modified */ 6689dd6f7c2SStefan Hajnoczi if (undo->modified_iov) { 6699dd6f7c2SStefan Hajnoczi *undo->modified_iov = undo->orig; 6709dd6f7c2SStefan Hajnoczi } 6719dd6f7c2SStefan Hajnoczi } 6729dd6f7c2SStefan Hajnoczi 6739dd6f7c2SStefan Hajnoczi size_t iov_discard_front_undoable(struct iovec **iov, 6749dd6f7c2SStefan Hajnoczi unsigned int *iov_cnt, 6759dd6f7c2SStefan Hajnoczi size_t bytes, 6769dd6f7c2SStefan Hajnoczi IOVDiscardUndo *undo) 677baacf047SPaolo Bonzini { 678baacf047SPaolo Bonzini size_t total = 0; 679baacf047SPaolo Bonzini struct iovec *cur; 680baacf047SPaolo Bonzini 6819dd6f7c2SStefan Hajnoczi if (undo) { 6829dd6f7c2SStefan Hajnoczi undo->modified_iov = NULL; 6839dd6f7c2SStefan Hajnoczi } 6849dd6f7c2SStefan Hajnoczi 685baacf047SPaolo Bonzini for (cur = *iov; *iov_cnt > 0; cur++) { 686baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 6879dd6f7c2SStefan Hajnoczi if (undo) { 6889dd6f7c2SStefan Hajnoczi undo->modified_iov = cur; 6899dd6f7c2SStefan Hajnoczi undo->orig = *cur; 6909dd6f7c2SStefan Hajnoczi } 6919dd6f7c2SStefan Hajnoczi 692baacf047SPaolo Bonzini cur->iov_base += bytes; 693baacf047SPaolo Bonzini cur->iov_len -= bytes; 694baacf047SPaolo Bonzini total += bytes; 695baacf047SPaolo Bonzini break; 696baacf047SPaolo Bonzini } 697baacf047SPaolo Bonzini 698baacf047SPaolo Bonzini bytes -= cur->iov_len; 699baacf047SPaolo Bonzini total += cur->iov_len; 700baacf047SPaolo Bonzini *iov_cnt -= 1; 701baacf047SPaolo Bonzini } 702baacf047SPaolo Bonzini 703baacf047SPaolo Bonzini *iov = cur; 704baacf047SPaolo Bonzini return total; 705baacf047SPaolo Bonzini } 706baacf047SPaolo Bonzini 7079dd6f7c2SStefan Hajnoczi size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, 708baacf047SPaolo Bonzini size_t bytes) 709baacf047SPaolo Bonzini { 7109dd6f7c2SStefan Hajnoczi return iov_discard_front_undoable(iov, iov_cnt, bytes, NULL); 7119dd6f7c2SStefan Hajnoczi } 7129dd6f7c2SStefan Hajnoczi 7139dd6f7c2SStefan Hajnoczi size_t iov_discard_back_undoable(struct iovec *iov, 7149dd6f7c2SStefan Hajnoczi unsigned int *iov_cnt, 7159dd6f7c2SStefan Hajnoczi size_t bytes, 7169dd6f7c2SStefan Hajnoczi IOVDiscardUndo *undo) 7179dd6f7c2SStefan Hajnoczi { 718baacf047SPaolo Bonzini size_t total = 0; 719baacf047SPaolo Bonzini struct iovec *cur; 720baacf047SPaolo Bonzini 7219dd6f7c2SStefan Hajnoczi if (undo) { 7229dd6f7c2SStefan Hajnoczi undo->modified_iov = NULL; 7239dd6f7c2SStefan Hajnoczi } 7249dd6f7c2SStefan Hajnoczi 725baacf047SPaolo Bonzini if (*iov_cnt == 0) { 726baacf047SPaolo Bonzini return 0; 727baacf047SPaolo Bonzini } 728baacf047SPaolo Bonzini 729baacf047SPaolo Bonzini cur = iov + (*iov_cnt - 1); 730baacf047SPaolo Bonzini 731baacf047SPaolo Bonzini while (*iov_cnt > 0) { 732baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 7339dd6f7c2SStefan Hajnoczi if (undo) { 7349dd6f7c2SStefan Hajnoczi undo->modified_iov = cur; 7359dd6f7c2SStefan Hajnoczi undo->orig = *cur; 7369dd6f7c2SStefan Hajnoczi } 7379dd6f7c2SStefan Hajnoczi 738baacf047SPaolo Bonzini cur->iov_len -= bytes; 739baacf047SPaolo Bonzini total += bytes; 740baacf047SPaolo Bonzini break; 741baacf047SPaolo Bonzini } 742baacf047SPaolo Bonzini 743baacf047SPaolo Bonzini bytes -= cur->iov_len; 744baacf047SPaolo Bonzini total += cur->iov_len; 745baacf047SPaolo Bonzini cur--; 746baacf047SPaolo Bonzini *iov_cnt -= 1; 747baacf047SPaolo Bonzini } 748baacf047SPaolo Bonzini 749baacf047SPaolo Bonzini return total; 750baacf047SPaolo Bonzini } 75158f423fbSKevin Wolf 7529dd6f7c2SStefan Hajnoczi size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, 7539dd6f7c2SStefan Hajnoczi size_t bytes) 7549dd6f7c2SStefan Hajnoczi { 7559dd6f7c2SStefan Hajnoczi return iov_discard_back_undoable(iov, iov_cnt, bytes, NULL); 7569dd6f7c2SStefan Hajnoczi } 7579dd6f7c2SStefan Hajnoczi 75858f423fbSKevin Wolf void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes) 75958f423fbSKevin Wolf { 76058f423fbSKevin Wolf size_t total; 76158f423fbSKevin Wolf unsigned int niov = qiov->niov; 76258f423fbSKevin Wolf 76358f423fbSKevin Wolf assert(qiov->size >= bytes); 76458f423fbSKevin Wolf total = iov_discard_back(qiov->iov, &niov, bytes); 76558f423fbSKevin Wolf assert(total == bytes); 76658f423fbSKevin Wolf 76758f423fbSKevin Wolf qiov->niov = niov; 76858f423fbSKevin Wolf qiov->size -= bytes; 76958f423fbSKevin Wolf } 770