1 /* 2 * Helpers for getting linearized buffers from iov / filling buffers into iovs 3 * 4 * Copyright IBM, Corp. 2007, 2008 5 * Copyright (C) 2010 Red Hat, Inc. 6 * 7 * Author(s): 8 * Anthony Liguori <aliguori@us.ibm.com> 9 * Amit Shah <amit.shah@redhat.com> 10 * Michael Tokarev <mjt@tls.msk.ru> 11 * 12 * This work is licensed under the terms of the GNU GPL, version 2. See 13 * the COPYING file in the top-level directory. 14 * 15 * Contributions after 2012-01-13 are licensed under the terms of the 16 * GNU GPL, version 2 or (at your option) any later version. 17 */ 18 19 #include "qemu/iov.h" 20 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 28 29 size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt, 30 size_t offset, const void *buf, size_t bytes) 31 { 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; 42 } 43 } 44 assert(offset == 0); 45 return done; 46 } 47 48 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, 49 size_t offset, void *buf, size_t bytes) 50 { 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; 61 } 62 } 63 assert(offset == 0); 64 return done; 65 } 66 67 size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, 68 size_t offset, int fillc, size_t bytes) 69 { 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; 80 } 81 } 82 assert(offset == 0); 83 return done; 84 } 85 86 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) 87 { 88 size_t len; 89 unsigned int i; 90 91 len = 0; 92 for (i = 0; i < iov_cnt; i++) { 93 len += iov[i].iov_len; 94 } 95 return len; 96 } 97 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) 101 { 102 #if defined CONFIG_IOVEC && defined 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; 134 } 135 break; 136 } 137 i++; 138 } 139 return ret; 140 #endif 141 } 142 143 ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, 144 size_t offset, size_t bytes, 145 bool do_send) 146 { 147 ssize_t ret; 148 unsigned si, ei; /* start and end indexes */ 149 if (bytes == 0) { 150 /* Catch the do-nothing case early, as otherwise we will pass an 151 * empty iovec to sendmsg/recvmsg(), and not all implementations 152 * accept this. 153 */ 154 return 0; 155 } 156 157 /* Find the start position, skipping `offset' bytes: 158 * first, skip all full-sized vector elements, */ 159 for (si = 0; si < iov_cnt && offset >= iov[si].iov_len; ++si) { 160 offset -= iov[si].iov_len; 161 } 162 if (offset) { 163 assert(si < iov_cnt); 164 /* second, skip `offset' bytes from the (now) first element, 165 * undo it on exit */ 166 iov[si].iov_base += offset; 167 iov[si].iov_len -= offset; 168 } 169 /* Find the end position skipping `bytes' bytes: */ 170 /* first, skip all full-sized elements */ 171 for (ei = si; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) { 172 bytes -= iov[ei].iov_len; 173 } 174 if (bytes) { 175 /* second, fixup the last element, and remember 176 * the length we've cut from the end of it in `bytes' */ 177 size_t tail; 178 assert(ei < iov_cnt); 179 assert(iov[ei].iov_len > bytes); 180 tail = iov[ei].iov_len - bytes; 181 iov[ei].iov_len = bytes; 182 bytes = tail; /* bytes is now equal to the tail size */ 183 ++ei; 184 } 185 186 ret = do_send_recv(sockfd, iov + si, ei - si, do_send); 187 188 /* Undo the changes above */ 189 if (offset) { 190 iov[si].iov_base -= offset; 191 iov[si].iov_len += offset; 192 } 193 if (bytes) { 194 iov[ei-1].iov_len += bytes; 195 } 196 197 return ret; 198 } 199 200 201 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, 202 FILE *fp, const char *prefix, size_t limit) 203 { 204 unsigned int i, v, b; 205 uint8_t *c; 206 207 c = iov[0].iov_base; 208 for (i = 0, v = 0, b = 0; b < limit; i++, b++) { 209 if (i == iov[v].iov_len) { 210 i = 0; v++; 211 if (v == iov_cnt) { 212 break; 213 } 214 c = iov[v].iov_base; 215 } 216 if ((b % 16) == 0) { 217 fprintf(fp, "%s: %04x:", prefix, b); 218 } 219 if ((b % 4) == 0) { 220 fprintf(fp, " "); 221 } 222 fprintf(fp, " %02x", c[i]); 223 if ((b % 16) == 15) { 224 fprintf(fp, "\n"); 225 } 226 } 227 if ((b % 16) != 0) { 228 fprintf(fp, "\n"); 229 } 230 } 231 232 unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, 233 const struct iovec *iov, unsigned int iov_cnt, 234 size_t offset, size_t bytes) 235 { 236 size_t len; 237 unsigned int i, j; 238 for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) { 239 if (offset >= iov[i].iov_len) { 240 offset -= iov[i].iov_len; 241 continue; 242 } 243 len = MIN(bytes, iov[i].iov_len - offset); 244 245 dst_iov[j].iov_base = iov[i].iov_base + offset; 246 dst_iov[j].iov_len = len; 247 j++; 248 bytes -= len; 249 offset = 0; 250 } 251 assert(offset == 0); 252 return j; 253 } 254 255 /* io vectors */ 256 257 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) 258 { 259 qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec)); 260 qiov->niov = 0; 261 qiov->nalloc = alloc_hint; 262 qiov->size = 0; 263 } 264 265 void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) 266 { 267 int i; 268 269 qiov->iov = iov; 270 qiov->niov = niov; 271 qiov->nalloc = -1; 272 qiov->size = 0; 273 for (i = 0; i < niov; i++) 274 qiov->size += iov[i].iov_len; 275 } 276 277 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) 278 { 279 assert(qiov->nalloc != -1); 280 281 if (qiov->niov == qiov->nalloc) { 282 qiov->nalloc = 2 * qiov->nalloc + 1; 283 qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec)); 284 } 285 qiov->iov[qiov->niov].iov_base = base; 286 qiov->iov[qiov->niov].iov_len = len; 287 qiov->size += len; 288 ++qiov->niov; 289 } 290 291 /* 292 * Concatenates (partial) iovecs from src_iov to the end of dst. 293 * It starts copying after skipping `soffset' bytes at the 294 * beginning of src and adds individual vectors from src to 295 * dst copies up to `sbytes' bytes total, or up to the end 296 * of src_iov if it comes first. This way, it is okay to specify 297 * very large value for `sbytes' to indicate "up to the end 298 * of src". 299 * Only vector pointers are processed, not the actual data buffers. 300 */ 301 void qemu_iovec_concat_iov(QEMUIOVector *dst, 302 struct iovec *src_iov, unsigned int src_cnt, 303 size_t soffset, size_t sbytes) 304 { 305 int i; 306 size_t done; 307 assert(dst->nalloc != -1); 308 for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { 309 if (soffset < src_iov[i].iov_len) { 310 size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); 311 qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); 312 done += len; 313 soffset = 0; 314 } else { 315 soffset -= src_iov[i].iov_len; 316 } 317 } 318 assert(soffset == 0); /* offset beyond end of src */ 319 } 320 321 /* 322 * Concatenates (partial) iovecs from src to the end of dst. 323 * It starts copying after skipping `soffset' bytes at the 324 * beginning of src and adds individual vectors from src to 325 * dst copies up to `sbytes' bytes total, or up to the end 326 * of src if it comes first. This way, it is okay to specify 327 * very large value for `sbytes' to indicate "up to the end 328 * of src". 329 * Only vector pointers are processed, not the actual data buffers. 330 */ 331 void qemu_iovec_concat(QEMUIOVector *dst, 332 QEMUIOVector *src, size_t soffset, size_t sbytes) 333 { 334 qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); 335 } 336 337 void qemu_iovec_destroy(QEMUIOVector *qiov) 338 { 339 assert(qiov->nalloc != -1); 340 341 qemu_iovec_reset(qiov); 342 g_free(qiov->iov); 343 qiov->nalloc = 0; 344 qiov->iov = NULL; 345 } 346 347 void qemu_iovec_reset(QEMUIOVector *qiov) 348 { 349 assert(qiov->nalloc != -1); 350 351 qiov->niov = 0; 352 qiov->size = 0; 353 } 354 355 size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, 356 void *buf, size_t bytes) 357 { 358 return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); 359 } 360 361 size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, 362 const void *buf, size_t bytes) 363 { 364 return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); 365 } 366 367 size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, 368 int fillc, size_t bytes) 369 { 370 return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); 371 } 372 373 size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, 374 size_t bytes) 375 { 376 size_t total = 0; 377 struct iovec *cur; 378 379 for (cur = *iov; *iov_cnt > 0; cur++) { 380 if (cur->iov_len > bytes) { 381 cur->iov_base += bytes; 382 cur->iov_len -= bytes; 383 total += bytes; 384 break; 385 } 386 387 bytes -= cur->iov_len; 388 total += cur->iov_len; 389 *iov_cnt -= 1; 390 } 391 392 *iov = cur; 393 return total; 394 } 395 396 size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, 397 size_t bytes) 398 { 399 size_t total = 0; 400 struct iovec *cur; 401 402 if (*iov_cnt == 0) { 403 return 0; 404 } 405 406 cur = iov + (*iov_cnt - 1); 407 408 while (*iov_cnt > 0) { 409 if (cur->iov_len > bytes) { 410 cur->iov_len -= bytes; 411 total += bytes; 412 break; 413 } 414 415 bytes -= cur->iov_len; 416 total += cur->iov_len; 417 cur--; 418 *iov_cnt -= 1; 419 } 420 421 return total; 422 } 423