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 19baacf047SPaolo Bonzini #include "qemu/iov.h" 20*cc99c6f5SStefan Weil #include "qemu/sockets.h" 21baacf047SPaolo Bonzini 22baacf047SPaolo Bonzini size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt, 23baacf047SPaolo Bonzini size_t offset, const void *buf, size_t bytes) 24baacf047SPaolo Bonzini { 25baacf047SPaolo Bonzini size_t done; 26baacf047SPaolo Bonzini unsigned int i; 27baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 28baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 29baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 30baacf047SPaolo Bonzini memcpy(iov[i].iov_base + offset, buf + done, len); 31baacf047SPaolo Bonzini done += len; 32baacf047SPaolo Bonzini offset = 0; 33baacf047SPaolo Bonzini } else { 34baacf047SPaolo Bonzini offset -= iov[i].iov_len; 35baacf047SPaolo Bonzini } 36baacf047SPaolo Bonzini } 37baacf047SPaolo Bonzini assert(offset == 0); 38baacf047SPaolo Bonzini return done; 39baacf047SPaolo Bonzini } 40baacf047SPaolo Bonzini 41baacf047SPaolo Bonzini size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, 42baacf047SPaolo Bonzini size_t offset, void *buf, size_t bytes) 43baacf047SPaolo Bonzini { 44baacf047SPaolo Bonzini size_t done; 45baacf047SPaolo Bonzini unsigned int i; 46baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 47baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 48baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 49baacf047SPaolo Bonzini memcpy(buf + done, iov[i].iov_base + offset, len); 50baacf047SPaolo Bonzini done += len; 51baacf047SPaolo Bonzini offset = 0; 52baacf047SPaolo Bonzini } else { 53baacf047SPaolo Bonzini offset -= iov[i].iov_len; 54baacf047SPaolo Bonzini } 55baacf047SPaolo Bonzini } 56baacf047SPaolo Bonzini assert(offset == 0); 57baacf047SPaolo Bonzini return done; 58baacf047SPaolo Bonzini } 59baacf047SPaolo Bonzini 60baacf047SPaolo Bonzini size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, 61baacf047SPaolo Bonzini size_t offset, int fillc, size_t bytes) 62baacf047SPaolo Bonzini { 63baacf047SPaolo Bonzini size_t done; 64baacf047SPaolo Bonzini unsigned int i; 65baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 66baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 67baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 68baacf047SPaolo Bonzini memset(iov[i].iov_base + offset, fillc, len); 69baacf047SPaolo Bonzini done += len; 70baacf047SPaolo Bonzini offset = 0; 71baacf047SPaolo Bonzini } else { 72baacf047SPaolo Bonzini offset -= iov[i].iov_len; 73baacf047SPaolo Bonzini } 74baacf047SPaolo Bonzini } 75baacf047SPaolo Bonzini assert(offset == 0); 76baacf047SPaolo Bonzini return done; 77baacf047SPaolo Bonzini } 78baacf047SPaolo Bonzini 79baacf047SPaolo Bonzini size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) 80baacf047SPaolo Bonzini { 81baacf047SPaolo Bonzini size_t len; 82baacf047SPaolo Bonzini unsigned int i; 83baacf047SPaolo Bonzini 84baacf047SPaolo Bonzini len = 0; 85baacf047SPaolo Bonzini for (i = 0; i < iov_cnt; i++) { 86baacf047SPaolo Bonzini len += iov[i].iov_len; 87baacf047SPaolo Bonzini } 88baacf047SPaolo Bonzini return len; 89baacf047SPaolo Bonzini } 90baacf047SPaolo Bonzini 91baacf047SPaolo Bonzini /* helper function for iov_send_recv() */ 92baacf047SPaolo Bonzini static ssize_t 93baacf047SPaolo Bonzini do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) 94baacf047SPaolo Bonzini { 959adea5f7SPaolo Bonzini #ifdef CONFIG_POSIX 96baacf047SPaolo Bonzini ssize_t ret; 97baacf047SPaolo Bonzini struct msghdr msg; 98baacf047SPaolo Bonzini memset(&msg, 0, sizeof(msg)); 99baacf047SPaolo Bonzini msg.msg_iov = iov; 100baacf047SPaolo Bonzini msg.msg_iovlen = iov_cnt; 101baacf047SPaolo Bonzini do { 102baacf047SPaolo Bonzini ret = do_send 103baacf047SPaolo Bonzini ? sendmsg(sockfd, &msg, 0) 104baacf047SPaolo Bonzini : recvmsg(sockfd, &msg, 0); 105baacf047SPaolo Bonzini } while (ret < 0 && errno == EINTR); 106baacf047SPaolo Bonzini return ret; 107baacf047SPaolo Bonzini #else 108baacf047SPaolo Bonzini /* else send piece-by-piece */ 109baacf047SPaolo Bonzini /*XXX Note: windows has WSASend() and WSARecv() */ 110baacf047SPaolo Bonzini unsigned i = 0; 111baacf047SPaolo Bonzini ssize_t ret = 0; 112baacf047SPaolo Bonzini while (i < iov_cnt) { 113baacf047SPaolo Bonzini ssize_t r = do_send 114baacf047SPaolo Bonzini ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0) 115baacf047SPaolo Bonzini : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0); 116baacf047SPaolo Bonzini if (r > 0) { 117baacf047SPaolo Bonzini ret += r; 118baacf047SPaolo Bonzini } else if (!r) { 119baacf047SPaolo Bonzini break; 120baacf047SPaolo Bonzini } else if (errno == EINTR) { 121baacf047SPaolo Bonzini continue; 122baacf047SPaolo Bonzini } else { 123baacf047SPaolo Bonzini /* else it is some "other" error, 124baacf047SPaolo Bonzini * only return if there was no data processed. */ 125baacf047SPaolo Bonzini if (ret == 0) { 126baacf047SPaolo Bonzini ret = -1; 127baacf047SPaolo Bonzini } 128baacf047SPaolo Bonzini break; 129baacf047SPaolo Bonzini } 130baacf047SPaolo Bonzini i++; 131baacf047SPaolo Bonzini } 132baacf047SPaolo Bonzini return ret; 133baacf047SPaolo Bonzini #endif 134baacf047SPaolo Bonzini } 135baacf047SPaolo Bonzini 136baacf047SPaolo Bonzini ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, 137baacf047SPaolo Bonzini size_t offset, size_t bytes, 138baacf047SPaolo Bonzini bool do_send) 139baacf047SPaolo Bonzini { 14083f75c26SPaolo Bonzini ssize_t total = 0; 141baacf047SPaolo Bonzini ssize_t ret; 1425209d675SPaolo Bonzini size_t orig_len, tail; 143f48869adSPaolo Bonzini unsigned niov; 1445209d675SPaolo Bonzini 14583f75c26SPaolo Bonzini while (bytes > 0) { 146baacf047SPaolo Bonzini /* Find the start position, skipping `offset' bytes: 147baacf047SPaolo Bonzini * first, skip all full-sized vector elements, */ 148f48869adSPaolo Bonzini for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) { 149f48869adSPaolo Bonzini offset -= iov[niov].iov_len; 150baacf047SPaolo Bonzini } 151cb6247a7SPaolo Bonzini 152f48869adSPaolo Bonzini /* niov == iov_cnt would only be valid if bytes == 0, which 15383f75c26SPaolo Bonzini * we already ruled out in the loop condition. */ 154f48869adSPaolo Bonzini assert(niov < iov_cnt); 155f48869adSPaolo Bonzini iov += niov; 156f48869adSPaolo Bonzini iov_cnt -= niov; 157cb6247a7SPaolo Bonzini 158cb6247a7SPaolo Bonzini if (offset) { 159baacf047SPaolo Bonzini /* second, skip `offset' bytes from the (now) first element, 160baacf047SPaolo Bonzini * undo it on exit */ 161cb6247a7SPaolo Bonzini iov[0].iov_base += offset; 162cb6247a7SPaolo Bonzini iov[0].iov_len -= offset; 163baacf047SPaolo Bonzini } 164baacf047SPaolo Bonzini /* Find the end position skipping `bytes' bytes: */ 165baacf047SPaolo Bonzini /* first, skip all full-sized elements */ 1665209d675SPaolo Bonzini tail = bytes; 167f48869adSPaolo Bonzini for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) { 168f48869adSPaolo Bonzini tail -= iov[niov].iov_len; 169baacf047SPaolo Bonzini } 1705209d675SPaolo Bonzini if (tail) { 1715209d675SPaolo Bonzini /* second, fixup the last element, and remember the original 1725209d675SPaolo Bonzini * length */ 173f48869adSPaolo Bonzini assert(niov < iov_cnt); 174f48869adSPaolo Bonzini assert(iov[niov].iov_len > tail); 175f48869adSPaolo Bonzini orig_len = iov[niov].iov_len; 176f48869adSPaolo Bonzini iov[niov++].iov_len = tail; 177f48869adSPaolo Bonzini ret = do_send_recv(sockfd, iov, niov, do_send); 17883f75c26SPaolo Bonzini /* Undo the changes above before checking for errors */ 179f48869adSPaolo Bonzini iov[niov-1].iov_len = orig_len; 1802be178a4SMichael Tokarev } else { 1812be178a4SMichael Tokarev ret = do_send_recv(sockfd, iov, niov, do_send); 1825209d675SPaolo Bonzini } 183baacf047SPaolo Bonzini if (offset) { 184cb6247a7SPaolo Bonzini iov[0].iov_base -= offset; 185cb6247a7SPaolo Bonzini iov[0].iov_len += offset; 186baacf047SPaolo Bonzini } 187baacf047SPaolo Bonzini 18883f75c26SPaolo Bonzini if (ret < 0) { 18983f75c26SPaolo Bonzini assert(errno != EINTR); 19083f75c26SPaolo Bonzini if (errno == EAGAIN && total > 0) { 19183f75c26SPaolo Bonzini return total; 19283f75c26SPaolo Bonzini } 19383f75c26SPaolo Bonzini return -1; 19483f75c26SPaolo Bonzini } 19583f75c26SPaolo Bonzini 19684004290SMORITA Kazutaka if (ret == 0 && !do_send) { 19784004290SMORITA Kazutaka /* recv returns 0 when the peer has performed an orderly 19884004290SMORITA Kazutaka * shutdown. */ 19984004290SMORITA Kazutaka break; 20084004290SMORITA Kazutaka } 20184004290SMORITA Kazutaka 20283f75c26SPaolo Bonzini /* Prepare for the next iteration */ 20383f75c26SPaolo Bonzini offset += ret; 20483f75c26SPaolo Bonzini total += ret; 20583f75c26SPaolo Bonzini bytes -= ret; 20683f75c26SPaolo Bonzini } 20783f75c26SPaolo Bonzini 20883f75c26SPaolo Bonzini return total; 209baacf047SPaolo Bonzini } 210baacf047SPaolo Bonzini 211baacf047SPaolo Bonzini 212baacf047SPaolo Bonzini void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, 213baacf047SPaolo Bonzini FILE *fp, const char *prefix, size_t limit) 214baacf047SPaolo Bonzini { 2156ff66f50SPeter Crosthwaite int v; 2166ff66f50SPeter Crosthwaite size_t size = 0; 2176ff66f50SPeter Crosthwaite char *buf; 218baacf047SPaolo Bonzini 2196ff66f50SPeter Crosthwaite for (v = 0; v < iov_cnt; v++) { 2206ff66f50SPeter Crosthwaite size += iov[v].iov_len; 221baacf047SPaolo Bonzini } 2226ff66f50SPeter Crosthwaite size = size > limit ? limit : size; 2236ff66f50SPeter Crosthwaite buf = g_malloc(size); 2246ff66f50SPeter Crosthwaite iov_to_buf(iov, iov_cnt, 0, buf, size); 2253568ac2aSEd Maste qemu_hexdump(buf, fp, prefix, size); 2266ff66f50SPeter Crosthwaite g_free(buf); 227baacf047SPaolo Bonzini } 228baacf047SPaolo Bonzini 229baacf047SPaolo Bonzini unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, 230baacf047SPaolo Bonzini const struct iovec *iov, unsigned int iov_cnt, 231baacf047SPaolo Bonzini size_t offset, size_t bytes) 232baacf047SPaolo Bonzini { 233baacf047SPaolo Bonzini size_t len; 234baacf047SPaolo Bonzini unsigned int i, j; 235baacf047SPaolo Bonzini for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) { 236baacf047SPaolo Bonzini if (offset >= iov[i].iov_len) { 237baacf047SPaolo Bonzini offset -= iov[i].iov_len; 238baacf047SPaolo Bonzini continue; 239baacf047SPaolo Bonzini } 240baacf047SPaolo Bonzini len = MIN(bytes, iov[i].iov_len - offset); 241baacf047SPaolo Bonzini 242baacf047SPaolo Bonzini dst_iov[j].iov_base = iov[i].iov_base + offset; 243baacf047SPaolo Bonzini dst_iov[j].iov_len = len; 244baacf047SPaolo Bonzini j++; 245baacf047SPaolo Bonzini bytes -= len; 246baacf047SPaolo Bonzini offset = 0; 247baacf047SPaolo Bonzini } 248baacf047SPaolo Bonzini assert(offset == 0); 249baacf047SPaolo Bonzini return j; 250baacf047SPaolo Bonzini } 251baacf047SPaolo Bonzini 252baacf047SPaolo Bonzini /* io vectors */ 253baacf047SPaolo Bonzini 254baacf047SPaolo Bonzini void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) 255baacf047SPaolo Bonzini { 256baacf047SPaolo Bonzini qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec)); 257baacf047SPaolo Bonzini qiov->niov = 0; 258baacf047SPaolo Bonzini qiov->nalloc = alloc_hint; 259baacf047SPaolo Bonzini qiov->size = 0; 260baacf047SPaolo Bonzini } 261baacf047SPaolo Bonzini 262baacf047SPaolo Bonzini void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) 263baacf047SPaolo Bonzini { 264baacf047SPaolo Bonzini int i; 265baacf047SPaolo Bonzini 266baacf047SPaolo Bonzini qiov->iov = iov; 267baacf047SPaolo Bonzini qiov->niov = niov; 268baacf047SPaolo Bonzini qiov->nalloc = -1; 269baacf047SPaolo Bonzini qiov->size = 0; 270baacf047SPaolo Bonzini for (i = 0; i < niov; i++) 271baacf047SPaolo Bonzini qiov->size += iov[i].iov_len; 272baacf047SPaolo Bonzini } 273baacf047SPaolo Bonzini 274baacf047SPaolo Bonzini void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) 275baacf047SPaolo Bonzini { 276baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 277baacf047SPaolo Bonzini 278baacf047SPaolo Bonzini if (qiov->niov == qiov->nalloc) { 279baacf047SPaolo Bonzini qiov->nalloc = 2 * qiov->nalloc + 1; 280baacf047SPaolo Bonzini qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec)); 281baacf047SPaolo Bonzini } 282baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_base = base; 283baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_len = len; 284baacf047SPaolo Bonzini qiov->size += len; 285baacf047SPaolo Bonzini ++qiov->niov; 286baacf047SPaolo Bonzini } 287baacf047SPaolo Bonzini 288baacf047SPaolo Bonzini /* 289baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src_iov to the end of dst. 290baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 291baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 292baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 293baacf047SPaolo Bonzini * of src_iov if it comes first. This way, it is okay to specify 294baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 295baacf047SPaolo Bonzini * of src". 296baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 297baacf047SPaolo Bonzini */ 298baacf047SPaolo Bonzini void qemu_iovec_concat_iov(QEMUIOVector *dst, 299baacf047SPaolo Bonzini struct iovec *src_iov, unsigned int src_cnt, 300baacf047SPaolo Bonzini size_t soffset, size_t sbytes) 301baacf047SPaolo Bonzini { 302baacf047SPaolo Bonzini int i; 303baacf047SPaolo Bonzini size_t done; 304facf98adSAneesh Kumar K.V 305facf98adSAneesh Kumar K.V if (!sbytes) { 306facf98adSAneesh Kumar K.V return; 307facf98adSAneesh Kumar K.V } 308baacf047SPaolo Bonzini assert(dst->nalloc != -1); 309baacf047SPaolo Bonzini for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { 310baacf047SPaolo Bonzini if (soffset < src_iov[i].iov_len) { 311baacf047SPaolo Bonzini size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); 312baacf047SPaolo Bonzini qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); 313baacf047SPaolo Bonzini done += len; 314baacf047SPaolo Bonzini soffset = 0; 315baacf047SPaolo Bonzini } else { 316baacf047SPaolo Bonzini soffset -= src_iov[i].iov_len; 317baacf047SPaolo Bonzini } 318baacf047SPaolo Bonzini } 319baacf047SPaolo Bonzini assert(soffset == 0); /* offset beyond end of src */ 320baacf047SPaolo Bonzini } 321baacf047SPaolo Bonzini 322baacf047SPaolo Bonzini /* 323baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src to the end of dst. 324baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 325baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 326baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 327baacf047SPaolo Bonzini * of src if it comes first. This way, it is okay to specify 328baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 329baacf047SPaolo Bonzini * of src". 330baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 331baacf047SPaolo Bonzini */ 332baacf047SPaolo Bonzini void qemu_iovec_concat(QEMUIOVector *dst, 333baacf047SPaolo Bonzini QEMUIOVector *src, size_t soffset, size_t sbytes) 334baacf047SPaolo Bonzini { 335baacf047SPaolo Bonzini qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); 336baacf047SPaolo Bonzini } 337baacf047SPaolo Bonzini 338baacf047SPaolo Bonzini void qemu_iovec_destroy(QEMUIOVector *qiov) 339baacf047SPaolo Bonzini { 340baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 341baacf047SPaolo Bonzini 342baacf047SPaolo Bonzini qemu_iovec_reset(qiov); 343baacf047SPaolo Bonzini g_free(qiov->iov); 344baacf047SPaolo Bonzini qiov->nalloc = 0; 345baacf047SPaolo Bonzini qiov->iov = NULL; 346baacf047SPaolo Bonzini } 347baacf047SPaolo Bonzini 348baacf047SPaolo Bonzini void qemu_iovec_reset(QEMUIOVector *qiov) 349baacf047SPaolo Bonzini { 350baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 351baacf047SPaolo Bonzini 352baacf047SPaolo Bonzini qiov->niov = 0; 353baacf047SPaolo Bonzini qiov->size = 0; 354baacf047SPaolo Bonzini } 355baacf047SPaolo Bonzini 356baacf047SPaolo Bonzini size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, 357baacf047SPaolo Bonzini void *buf, size_t bytes) 358baacf047SPaolo Bonzini { 359baacf047SPaolo Bonzini return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); 360baacf047SPaolo Bonzini } 361baacf047SPaolo Bonzini 362baacf047SPaolo Bonzini size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, 363baacf047SPaolo Bonzini const void *buf, size_t bytes) 364baacf047SPaolo Bonzini { 365baacf047SPaolo Bonzini return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); 366baacf047SPaolo Bonzini } 367baacf047SPaolo Bonzini 368baacf047SPaolo Bonzini size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, 369baacf047SPaolo Bonzini int fillc, size_t bytes) 370baacf047SPaolo Bonzini { 371baacf047SPaolo Bonzini return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); 372baacf047SPaolo Bonzini } 373baacf047SPaolo Bonzini 374f70d7f7eSBenoît Canet /** 375f70d7f7eSBenoît Canet * Check that I/O vector contents are identical 376f70d7f7eSBenoît Canet * 377f70d7f7eSBenoît Canet * The IO vectors must have the same structure (same length of all parts). 378f70d7f7eSBenoît Canet * A typical usage is to compare vectors created with qemu_iovec_clone(). 379f70d7f7eSBenoît Canet * 380f70d7f7eSBenoît Canet * @a: I/O vector 381f70d7f7eSBenoît Canet * @b: I/O vector 382f70d7f7eSBenoît Canet * @ret: Offset to first mismatching byte or -1 if match 383f70d7f7eSBenoît Canet */ 384f70d7f7eSBenoît Canet ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b) 385f70d7f7eSBenoît Canet { 386f70d7f7eSBenoît Canet int i; 387f70d7f7eSBenoît Canet ssize_t offset = 0; 388f70d7f7eSBenoît Canet 389f70d7f7eSBenoît Canet assert(a->niov == b->niov); 390f70d7f7eSBenoît Canet for (i = 0; i < a->niov; i++) { 391f70d7f7eSBenoît Canet size_t len = 0; 392f70d7f7eSBenoît Canet uint8_t *p = (uint8_t *)a->iov[i].iov_base; 393f70d7f7eSBenoît Canet uint8_t *q = (uint8_t *)b->iov[i].iov_base; 394f70d7f7eSBenoît Canet 395f70d7f7eSBenoît Canet assert(a->iov[i].iov_len == b->iov[i].iov_len); 396f70d7f7eSBenoît Canet while (len < a->iov[i].iov_len && *p++ == *q++) { 397f70d7f7eSBenoît Canet len++; 398f70d7f7eSBenoît Canet } 399f70d7f7eSBenoît Canet 400f70d7f7eSBenoît Canet offset += len; 401f70d7f7eSBenoît Canet 402f70d7f7eSBenoît Canet if (len != a->iov[i].iov_len) { 403f70d7f7eSBenoît Canet return offset; 404f70d7f7eSBenoît Canet } 405f70d7f7eSBenoît Canet } 406f70d7f7eSBenoît Canet return -1; 407f70d7f7eSBenoît Canet } 408f70d7f7eSBenoît Canet 409f70d7f7eSBenoît Canet typedef struct { 410f70d7f7eSBenoît Canet int src_index; 411f70d7f7eSBenoît Canet struct iovec *src_iov; 412f70d7f7eSBenoît Canet void *dest_base; 413f70d7f7eSBenoît Canet } IOVectorSortElem; 414f70d7f7eSBenoît Canet 415f70d7f7eSBenoît Canet static int sortelem_cmp_src_base(const void *a, const void *b) 416f70d7f7eSBenoît Canet { 417f70d7f7eSBenoît Canet const IOVectorSortElem *elem_a = a; 418f70d7f7eSBenoît Canet const IOVectorSortElem *elem_b = b; 419f70d7f7eSBenoît Canet 420f70d7f7eSBenoît Canet /* Don't overflow */ 421f70d7f7eSBenoît Canet if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) { 422f70d7f7eSBenoît Canet return -1; 423f70d7f7eSBenoît Canet } else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) { 424f70d7f7eSBenoît Canet return 1; 425f70d7f7eSBenoît Canet } else { 426f70d7f7eSBenoît Canet return 0; 427f70d7f7eSBenoît Canet } 428f70d7f7eSBenoît Canet } 429f70d7f7eSBenoît Canet 430f70d7f7eSBenoît Canet static int sortelem_cmp_src_index(const void *a, const void *b) 431f70d7f7eSBenoît Canet { 432f70d7f7eSBenoît Canet const IOVectorSortElem *elem_a = a; 433f70d7f7eSBenoît Canet const IOVectorSortElem *elem_b = b; 434f70d7f7eSBenoît Canet 435f70d7f7eSBenoît Canet return elem_a->src_index - elem_b->src_index; 436f70d7f7eSBenoît Canet } 437f70d7f7eSBenoît Canet 438f70d7f7eSBenoît Canet /** 439f70d7f7eSBenoît Canet * Copy contents of I/O vector 440f70d7f7eSBenoît Canet * 441f70d7f7eSBenoît Canet * The relative relationships of overlapping iovecs are preserved. This is 442f70d7f7eSBenoît Canet * necessary to ensure identical semantics in the cloned I/O vector. 443f70d7f7eSBenoît Canet */ 444f70d7f7eSBenoît Canet void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf) 445f70d7f7eSBenoît Canet { 446f70d7f7eSBenoît Canet IOVectorSortElem sortelems[src->niov]; 447f70d7f7eSBenoît Canet void *last_end; 448f70d7f7eSBenoît Canet int i; 449f70d7f7eSBenoît Canet 450f70d7f7eSBenoît Canet /* Sort by source iovecs by base address */ 451f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 452f70d7f7eSBenoît Canet sortelems[i].src_index = i; 453f70d7f7eSBenoît Canet sortelems[i].src_iov = &src->iov[i]; 454f70d7f7eSBenoît Canet } 455f70d7f7eSBenoît Canet qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base); 456f70d7f7eSBenoît Canet 457f70d7f7eSBenoît Canet /* Allocate buffer space taking into account overlapping iovecs */ 458f70d7f7eSBenoît Canet last_end = NULL; 459f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 460f70d7f7eSBenoît Canet struct iovec *cur = sortelems[i].src_iov; 461f70d7f7eSBenoît Canet ptrdiff_t rewind = 0; 462f70d7f7eSBenoît Canet 463f70d7f7eSBenoît Canet /* Detect overlap */ 464f70d7f7eSBenoît Canet if (last_end && last_end > cur->iov_base) { 465f70d7f7eSBenoît Canet rewind = last_end - cur->iov_base; 466f70d7f7eSBenoît Canet } 467f70d7f7eSBenoît Canet 468f70d7f7eSBenoît Canet sortelems[i].dest_base = buf - rewind; 469f70d7f7eSBenoît Canet buf += cur->iov_len - MIN(rewind, cur->iov_len); 470f70d7f7eSBenoît Canet last_end = MAX(cur->iov_base + cur->iov_len, last_end); 471f70d7f7eSBenoît Canet } 472f70d7f7eSBenoît Canet 473f70d7f7eSBenoît Canet /* Sort by source iovec index and build destination iovec */ 474f70d7f7eSBenoît Canet qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index); 475f70d7f7eSBenoît Canet for (i = 0; i < src->niov; i++) { 476f70d7f7eSBenoît Canet qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len); 477f70d7f7eSBenoît Canet } 478f70d7f7eSBenoît Canet } 479f70d7f7eSBenoît Canet 480baacf047SPaolo Bonzini size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, 481baacf047SPaolo Bonzini size_t bytes) 482baacf047SPaolo Bonzini { 483baacf047SPaolo Bonzini size_t total = 0; 484baacf047SPaolo Bonzini struct iovec *cur; 485baacf047SPaolo Bonzini 486baacf047SPaolo Bonzini for (cur = *iov; *iov_cnt > 0; cur++) { 487baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 488baacf047SPaolo Bonzini cur->iov_base += bytes; 489baacf047SPaolo Bonzini cur->iov_len -= bytes; 490baacf047SPaolo Bonzini total += bytes; 491baacf047SPaolo Bonzini break; 492baacf047SPaolo Bonzini } 493baacf047SPaolo Bonzini 494baacf047SPaolo Bonzini bytes -= cur->iov_len; 495baacf047SPaolo Bonzini total += cur->iov_len; 496baacf047SPaolo Bonzini *iov_cnt -= 1; 497baacf047SPaolo Bonzini } 498baacf047SPaolo Bonzini 499baacf047SPaolo Bonzini *iov = cur; 500baacf047SPaolo Bonzini return total; 501baacf047SPaolo Bonzini } 502baacf047SPaolo Bonzini 503baacf047SPaolo Bonzini size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, 504baacf047SPaolo Bonzini size_t bytes) 505baacf047SPaolo Bonzini { 506baacf047SPaolo Bonzini size_t total = 0; 507baacf047SPaolo Bonzini struct iovec *cur; 508baacf047SPaolo Bonzini 509baacf047SPaolo Bonzini if (*iov_cnt == 0) { 510baacf047SPaolo Bonzini return 0; 511baacf047SPaolo Bonzini } 512baacf047SPaolo Bonzini 513baacf047SPaolo Bonzini cur = iov + (*iov_cnt - 1); 514baacf047SPaolo Bonzini 515baacf047SPaolo Bonzini while (*iov_cnt > 0) { 516baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 517baacf047SPaolo Bonzini cur->iov_len -= bytes; 518baacf047SPaolo Bonzini total += bytes; 519baacf047SPaolo Bonzini break; 520baacf047SPaolo Bonzini } 521baacf047SPaolo Bonzini 522baacf047SPaolo Bonzini bytes -= cur->iov_len; 523baacf047SPaolo Bonzini total += cur->iov_len; 524baacf047SPaolo Bonzini cur--; 525baacf047SPaolo Bonzini *iov_cnt -= 1; 526baacf047SPaolo Bonzini } 527baacf047SPaolo Bonzini 528baacf047SPaolo Bonzini return total; 529baacf047SPaolo Bonzini } 530