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" 20baacf047SPaolo Bonzini 21baacf047SPaolo Bonzini #ifdef _WIN32 22baacf047SPaolo Bonzini # include <windows.h> 23baacf047SPaolo Bonzini # include <winsock2.h> 24baacf047SPaolo Bonzini #else 25baacf047SPaolo Bonzini # include <sys/types.h> 26baacf047SPaolo Bonzini # include <sys/socket.h> 27baacf047SPaolo Bonzini #endif 28baacf047SPaolo Bonzini 29baacf047SPaolo Bonzini size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt, 30baacf047SPaolo Bonzini size_t offset, const void *buf, size_t bytes) 31baacf047SPaolo Bonzini { 32baacf047SPaolo Bonzini size_t done; 33baacf047SPaolo Bonzini unsigned int i; 34baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 35baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 36baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 37baacf047SPaolo Bonzini memcpy(iov[i].iov_base + offset, buf + done, len); 38baacf047SPaolo Bonzini done += len; 39baacf047SPaolo Bonzini offset = 0; 40baacf047SPaolo Bonzini } else { 41baacf047SPaolo Bonzini offset -= iov[i].iov_len; 42baacf047SPaolo Bonzini } 43baacf047SPaolo Bonzini } 44baacf047SPaolo Bonzini assert(offset == 0); 45baacf047SPaolo Bonzini return done; 46baacf047SPaolo Bonzini } 47baacf047SPaolo Bonzini 48baacf047SPaolo Bonzini size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, 49baacf047SPaolo Bonzini size_t offset, void *buf, size_t bytes) 50baacf047SPaolo Bonzini { 51baacf047SPaolo Bonzini size_t done; 52baacf047SPaolo Bonzini unsigned int i; 53baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 54baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 55baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 56baacf047SPaolo Bonzini memcpy(buf + done, iov[i].iov_base + offset, len); 57baacf047SPaolo Bonzini done += len; 58baacf047SPaolo Bonzini offset = 0; 59baacf047SPaolo Bonzini } else { 60baacf047SPaolo Bonzini offset -= iov[i].iov_len; 61baacf047SPaolo Bonzini } 62baacf047SPaolo Bonzini } 63baacf047SPaolo Bonzini assert(offset == 0); 64baacf047SPaolo Bonzini return done; 65baacf047SPaolo Bonzini } 66baacf047SPaolo Bonzini 67baacf047SPaolo Bonzini size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, 68baacf047SPaolo Bonzini size_t offset, int fillc, size_t bytes) 69baacf047SPaolo Bonzini { 70baacf047SPaolo Bonzini size_t done; 71baacf047SPaolo Bonzini unsigned int i; 72baacf047SPaolo Bonzini for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { 73baacf047SPaolo Bonzini if (offset < iov[i].iov_len) { 74baacf047SPaolo Bonzini size_t len = MIN(iov[i].iov_len - offset, bytes - done); 75baacf047SPaolo Bonzini memset(iov[i].iov_base + offset, fillc, len); 76baacf047SPaolo Bonzini done += len; 77baacf047SPaolo Bonzini offset = 0; 78baacf047SPaolo Bonzini } else { 79baacf047SPaolo Bonzini offset -= iov[i].iov_len; 80baacf047SPaolo Bonzini } 81baacf047SPaolo Bonzini } 82baacf047SPaolo Bonzini assert(offset == 0); 83baacf047SPaolo Bonzini return done; 84baacf047SPaolo Bonzini } 85baacf047SPaolo Bonzini 86baacf047SPaolo Bonzini size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) 87baacf047SPaolo Bonzini { 88baacf047SPaolo Bonzini size_t len; 89baacf047SPaolo Bonzini unsigned int i; 90baacf047SPaolo Bonzini 91baacf047SPaolo Bonzini len = 0; 92baacf047SPaolo Bonzini for (i = 0; i < iov_cnt; i++) { 93baacf047SPaolo Bonzini len += iov[i].iov_len; 94baacf047SPaolo Bonzini } 95baacf047SPaolo Bonzini return len; 96baacf047SPaolo Bonzini } 97baacf047SPaolo Bonzini 98baacf047SPaolo Bonzini /* helper function for iov_send_recv() */ 99baacf047SPaolo Bonzini static ssize_t 100baacf047SPaolo Bonzini do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) 101baacf047SPaolo Bonzini { 102baacf047SPaolo Bonzini #if defined CONFIG_IOVEC && defined CONFIG_POSIX 103baacf047SPaolo Bonzini ssize_t ret; 104baacf047SPaolo Bonzini struct msghdr msg; 105baacf047SPaolo Bonzini memset(&msg, 0, sizeof(msg)); 106baacf047SPaolo Bonzini msg.msg_iov = iov; 107baacf047SPaolo Bonzini msg.msg_iovlen = iov_cnt; 108baacf047SPaolo Bonzini do { 109baacf047SPaolo Bonzini ret = do_send 110baacf047SPaolo Bonzini ? sendmsg(sockfd, &msg, 0) 111baacf047SPaolo Bonzini : recvmsg(sockfd, &msg, 0); 112baacf047SPaolo Bonzini } while (ret < 0 && errno == EINTR); 113baacf047SPaolo Bonzini return ret; 114baacf047SPaolo Bonzini #else 115baacf047SPaolo Bonzini /* else send piece-by-piece */ 116baacf047SPaolo Bonzini /*XXX Note: windows has WSASend() and WSARecv() */ 117baacf047SPaolo Bonzini unsigned i = 0; 118baacf047SPaolo Bonzini ssize_t ret = 0; 119baacf047SPaolo Bonzini while (i < iov_cnt) { 120baacf047SPaolo Bonzini ssize_t r = do_send 121baacf047SPaolo Bonzini ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0) 122baacf047SPaolo Bonzini : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0); 123baacf047SPaolo Bonzini if (r > 0) { 124baacf047SPaolo Bonzini ret += r; 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 } 137baacf047SPaolo Bonzini i++; 138baacf047SPaolo Bonzini } 139baacf047SPaolo Bonzini return ret; 140baacf047SPaolo Bonzini #endif 141baacf047SPaolo Bonzini } 142baacf047SPaolo Bonzini 143baacf047SPaolo Bonzini ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, 144baacf047SPaolo Bonzini size_t offset, size_t bytes, 145baacf047SPaolo Bonzini bool do_send) 146baacf047SPaolo Bonzini { 147baacf047SPaolo Bonzini ssize_t ret; 148baacf047SPaolo Bonzini unsigned si, ei; /* start and end indexes */ 149baacf047SPaolo Bonzini if (bytes == 0) { 150baacf047SPaolo Bonzini /* Catch the do-nothing case early, as otherwise we will pass an 151baacf047SPaolo Bonzini * empty iovec to sendmsg/recvmsg(), and not all implementations 152baacf047SPaolo Bonzini * accept this. 153baacf047SPaolo Bonzini */ 154baacf047SPaolo Bonzini return 0; 155baacf047SPaolo Bonzini } 156baacf047SPaolo Bonzini 157baacf047SPaolo Bonzini /* Find the start position, skipping `offset' bytes: 158baacf047SPaolo Bonzini * first, skip all full-sized vector elements, */ 159baacf047SPaolo Bonzini for (si = 0; si < iov_cnt && offset >= iov[si].iov_len; ++si) { 160baacf047SPaolo Bonzini offset -= iov[si].iov_len; 161baacf047SPaolo Bonzini } 162baacf047SPaolo Bonzini if (offset) { 163baacf047SPaolo Bonzini assert(si < iov_cnt); 164baacf047SPaolo Bonzini /* second, skip `offset' bytes from the (now) first element, 165baacf047SPaolo Bonzini * undo it on exit */ 166baacf047SPaolo Bonzini iov[si].iov_base += offset; 167baacf047SPaolo Bonzini iov[si].iov_len -= offset; 168baacf047SPaolo Bonzini } 169baacf047SPaolo Bonzini /* Find the end position skipping `bytes' bytes: */ 170baacf047SPaolo Bonzini /* first, skip all full-sized elements */ 171baacf047SPaolo Bonzini for (ei = si; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) { 172baacf047SPaolo Bonzini bytes -= iov[ei].iov_len; 173baacf047SPaolo Bonzini } 174baacf047SPaolo Bonzini if (bytes) { 175baacf047SPaolo Bonzini /* second, fixup the last element, and remember 176baacf047SPaolo Bonzini * the length we've cut from the end of it in `bytes' */ 177baacf047SPaolo Bonzini size_t tail; 178baacf047SPaolo Bonzini assert(ei < iov_cnt); 179baacf047SPaolo Bonzini assert(iov[ei].iov_len > bytes); 180baacf047SPaolo Bonzini tail = iov[ei].iov_len - bytes; 181baacf047SPaolo Bonzini iov[ei].iov_len = bytes; 182baacf047SPaolo Bonzini bytes = tail; /* bytes is now equal to the tail size */ 183baacf047SPaolo Bonzini ++ei; 184baacf047SPaolo Bonzini } 185baacf047SPaolo Bonzini 186baacf047SPaolo Bonzini ret = do_send_recv(sockfd, iov + si, ei - si, do_send); 187baacf047SPaolo Bonzini 188baacf047SPaolo Bonzini /* Undo the changes above */ 189baacf047SPaolo Bonzini if (offset) { 190baacf047SPaolo Bonzini iov[si].iov_base -= offset; 191baacf047SPaolo Bonzini iov[si].iov_len += offset; 192baacf047SPaolo Bonzini } 193baacf047SPaolo Bonzini if (bytes) { 194baacf047SPaolo Bonzini iov[ei-1].iov_len += bytes; 195baacf047SPaolo Bonzini } 196baacf047SPaolo Bonzini 197baacf047SPaolo Bonzini return ret; 198baacf047SPaolo Bonzini } 199baacf047SPaolo Bonzini 200baacf047SPaolo Bonzini 201baacf047SPaolo Bonzini void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, 202baacf047SPaolo Bonzini FILE *fp, const char *prefix, size_t limit) 203baacf047SPaolo Bonzini { 204*6ff66f50SPeter Crosthwaite int v; 205*6ff66f50SPeter Crosthwaite size_t size = 0; 206*6ff66f50SPeter Crosthwaite char *buf; 207baacf047SPaolo Bonzini 208*6ff66f50SPeter Crosthwaite for (v = 0; v < iov_cnt; v++) { 209*6ff66f50SPeter Crosthwaite size += iov[v].iov_len; 210baacf047SPaolo Bonzini } 211*6ff66f50SPeter Crosthwaite size = size > limit ? limit : size; 212*6ff66f50SPeter Crosthwaite buf = g_malloc(size); 213*6ff66f50SPeter Crosthwaite iov_to_buf(iov, iov_cnt, 0, buf, size); 214*6ff66f50SPeter Crosthwaite hexdump(buf, fp, prefix, size); 215*6ff66f50SPeter Crosthwaite g_free(buf); 216baacf047SPaolo Bonzini } 217baacf047SPaolo Bonzini 218baacf047SPaolo Bonzini unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, 219baacf047SPaolo Bonzini const struct iovec *iov, unsigned int iov_cnt, 220baacf047SPaolo Bonzini size_t offset, size_t bytes) 221baacf047SPaolo Bonzini { 222baacf047SPaolo Bonzini size_t len; 223baacf047SPaolo Bonzini unsigned int i, j; 224baacf047SPaolo Bonzini for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) { 225baacf047SPaolo Bonzini if (offset >= iov[i].iov_len) { 226baacf047SPaolo Bonzini offset -= iov[i].iov_len; 227baacf047SPaolo Bonzini continue; 228baacf047SPaolo Bonzini } 229baacf047SPaolo Bonzini len = MIN(bytes, iov[i].iov_len - offset); 230baacf047SPaolo Bonzini 231baacf047SPaolo Bonzini dst_iov[j].iov_base = iov[i].iov_base + offset; 232baacf047SPaolo Bonzini dst_iov[j].iov_len = len; 233baacf047SPaolo Bonzini j++; 234baacf047SPaolo Bonzini bytes -= len; 235baacf047SPaolo Bonzini offset = 0; 236baacf047SPaolo Bonzini } 237baacf047SPaolo Bonzini assert(offset == 0); 238baacf047SPaolo Bonzini return j; 239baacf047SPaolo Bonzini } 240baacf047SPaolo Bonzini 241baacf047SPaolo Bonzini /* io vectors */ 242baacf047SPaolo Bonzini 243baacf047SPaolo Bonzini void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) 244baacf047SPaolo Bonzini { 245baacf047SPaolo Bonzini qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec)); 246baacf047SPaolo Bonzini qiov->niov = 0; 247baacf047SPaolo Bonzini qiov->nalloc = alloc_hint; 248baacf047SPaolo Bonzini qiov->size = 0; 249baacf047SPaolo Bonzini } 250baacf047SPaolo Bonzini 251baacf047SPaolo Bonzini void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) 252baacf047SPaolo Bonzini { 253baacf047SPaolo Bonzini int i; 254baacf047SPaolo Bonzini 255baacf047SPaolo Bonzini qiov->iov = iov; 256baacf047SPaolo Bonzini qiov->niov = niov; 257baacf047SPaolo Bonzini qiov->nalloc = -1; 258baacf047SPaolo Bonzini qiov->size = 0; 259baacf047SPaolo Bonzini for (i = 0; i < niov; i++) 260baacf047SPaolo Bonzini qiov->size += iov[i].iov_len; 261baacf047SPaolo Bonzini } 262baacf047SPaolo Bonzini 263baacf047SPaolo Bonzini void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) 264baacf047SPaolo Bonzini { 265baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 266baacf047SPaolo Bonzini 267baacf047SPaolo Bonzini if (qiov->niov == qiov->nalloc) { 268baacf047SPaolo Bonzini qiov->nalloc = 2 * qiov->nalloc + 1; 269baacf047SPaolo Bonzini qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec)); 270baacf047SPaolo Bonzini } 271baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_base = base; 272baacf047SPaolo Bonzini qiov->iov[qiov->niov].iov_len = len; 273baacf047SPaolo Bonzini qiov->size += len; 274baacf047SPaolo Bonzini ++qiov->niov; 275baacf047SPaolo Bonzini } 276baacf047SPaolo Bonzini 277baacf047SPaolo Bonzini /* 278baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src_iov to the end of dst. 279baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 280baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 281baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 282baacf047SPaolo Bonzini * of src_iov if it comes first. This way, it is okay to specify 283baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 284baacf047SPaolo Bonzini * of src". 285baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 286baacf047SPaolo Bonzini */ 287baacf047SPaolo Bonzini void qemu_iovec_concat_iov(QEMUIOVector *dst, 288baacf047SPaolo Bonzini struct iovec *src_iov, unsigned int src_cnt, 289baacf047SPaolo Bonzini size_t soffset, size_t sbytes) 290baacf047SPaolo Bonzini { 291baacf047SPaolo Bonzini int i; 292baacf047SPaolo Bonzini size_t done; 293facf98adSAneesh Kumar K.V 294facf98adSAneesh Kumar K.V if (!sbytes) { 295facf98adSAneesh Kumar K.V return; 296facf98adSAneesh Kumar K.V } 297baacf047SPaolo Bonzini assert(dst->nalloc != -1); 298baacf047SPaolo Bonzini for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { 299baacf047SPaolo Bonzini if (soffset < src_iov[i].iov_len) { 300baacf047SPaolo Bonzini size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); 301baacf047SPaolo Bonzini qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); 302baacf047SPaolo Bonzini done += len; 303baacf047SPaolo Bonzini soffset = 0; 304baacf047SPaolo Bonzini } else { 305baacf047SPaolo Bonzini soffset -= src_iov[i].iov_len; 306baacf047SPaolo Bonzini } 307baacf047SPaolo Bonzini } 308baacf047SPaolo Bonzini assert(soffset == 0); /* offset beyond end of src */ 309baacf047SPaolo Bonzini } 310baacf047SPaolo Bonzini 311baacf047SPaolo Bonzini /* 312baacf047SPaolo Bonzini * Concatenates (partial) iovecs from src to the end of dst. 313baacf047SPaolo Bonzini * It starts copying after skipping `soffset' bytes at the 314baacf047SPaolo Bonzini * beginning of src and adds individual vectors from src to 315baacf047SPaolo Bonzini * dst copies up to `sbytes' bytes total, or up to the end 316baacf047SPaolo Bonzini * of src if it comes first. This way, it is okay to specify 317baacf047SPaolo Bonzini * very large value for `sbytes' to indicate "up to the end 318baacf047SPaolo Bonzini * of src". 319baacf047SPaolo Bonzini * Only vector pointers are processed, not the actual data buffers. 320baacf047SPaolo Bonzini */ 321baacf047SPaolo Bonzini void qemu_iovec_concat(QEMUIOVector *dst, 322baacf047SPaolo Bonzini QEMUIOVector *src, size_t soffset, size_t sbytes) 323baacf047SPaolo Bonzini { 324baacf047SPaolo Bonzini qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); 325baacf047SPaolo Bonzini } 326baacf047SPaolo Bonzini 327baacf047SPaolo Bonzini void qemu_iovec_destroy(QEMUIOVector *qiov) 328baacf047SPaolo Bonzini { 329baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 330baacf047SPaolo Bonzini 331baacf047SPaolo Bonzini qemu_iovec_reset(qiov); 332baacf047SPaolo Bonzini g_free(qiov->iov); 333baacf047SPaolo Bonzini qiov->nalloc = 0; 334baacf047SPaolo Bonzini qiov->iov = NULL; 335baacf047SPaolo Bonzini } 336baacf047SPaolo Bonzini 337baacf047SPaolo Bonzini void qemu_iovec_reset(QEMUIOVector *qiov) 338baacf047SPaolo Bonzini { 339baacf047SPaolo Bonzini assert(qiov->nalloc != -1); 340baacf047SPaolo Bonzini 341baacf047SPaolo Bonzini qiov->niov = 0; 342baacf047SPaolo Bonzini qiov->size = 0; 343baacf047SPaolo Bonzini } 344baacf047SPaolo Bonzini 345baacf047SPaolo Bonzini size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, 346baacf047SPaolo Bonzini void *buf, size_t bytes) 347baacf047SPaolo Bonzini { 348baacf047SPaolo Bonzini return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); 349baacf047SPaolo Bonzini } 350baacf047SPaolo Bonzini 351baacf047SPaolo Bonzini size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, 352baacf047SPaolo Bonzini const void *buf, size_t bytes) 353baacf047SPaolo Bonzini { 354baacf047SPaolo Bonzini return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); 355baacf047SPaolo Bonzini } 356baacf047SPaolo Bonzini 357baacf047SPaolo Bonzini size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, 358baacf047SPaolo Bonzini int fillc, size_t bytes) 359baacf047SPaolo Bonzini { 360baacf047SPaolo Bonzini return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); 361baacf047SPaolo Bonzini } 362baacf047SPaolo Bonzini 363baacf047SPaolo Bonzini size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, 364baacf047SPaolo Bonzini size_t bytes) 365baacf047SPaolo Bonzini { 366baacf047SPaolo Bonzini size_t total = 0; 367baacf047SPaolo Bonzini struct iovec *cur; 368baacf047SPaolo Bonzini 369baacf047SPaolo Bonzini for (cur = *iov; *iov_cnt > 0; cur++) { 370baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 371baacf047SPaolo Bonzini cur->iov_base += bytes; 372baacf047SPaolo Bonzini cur->iov_len -= bytes; 373baacf047SPaolo Bonzini total += bytes; 374baacf047SPaolo Bonzini break; 375baacf047SPaolo Bonzini } 376baacf047SPaolo Bonzini 377baacf047SPaolo Bonzini bytes -= cur->iov_len; 378baacf047SPaolo Bonzini total += cur->iov_len; 379baacf047SPaolo Bonzini *iov_cnt -= 1; 380baacf047SPaolo Bonzini } 381baacf047SPaolo Bonzini 382baacf047SPaolo Bonzini *iov = cur; 383baacf047SPaolo Bonzini return total; 384baacf047SPaolo Bonzini } 385baacf047SPaolo Bonzini 386baacf047SPaolo Bonzini size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, 387baacf047SPaolo Bonzini size_t bytes) 388baacf047SPaolo Bonzini { 389baacf047SPaolo Bonzini size_t total = 0; 390baacf047SPaolo Bonzini struct iovec *cur; 391baacf047SPaolo Bonzini 392baacf047SPaolo Bonzini if (*iov_cnt == 0) { 393baacf047SPaolo Bonzini return 0; 394baacf047SPaolo Bonzini } 395baacf047SPaolo Bonzini 396baacf047SPaolo Bonzini cur = iov + (*iov_cnt - 1); 397baacf047SPaolo Bonzini 398baacf047SPaolo Bonzini while (*iov_cnt > 0) { 399baacf047SPaolo Bonzini if (cur->iov_len > bytes) { 400baacf047SPaolo Bonzini cur->iov_len -= bytes; 401baacf047SPaolo Bonzini total += bytes; 402baacf047SPaolo Bonzini break; 403baacf047SPaolo Bonzini } 404baacf047SPaolo Bonzini 405baacf047SPaolo Bonzini bytes -= cur->iov_len; 406baacf047SPaolo Bonzini total += cur->iov_len; 407baacf047SPaolo Bonzini cur--; 408baacf047SPaolo Bonzini *iov_cnt -= 1; 409baacf047SPaolo Bonzini } 410baacf047SPaolo Bonzini 411baacf047SPaolo Bonzini return total; 412baacf047SPaolo Bonzini } 413