migration/qemu-file.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "qemu-common.h"
  25 #include "qemu/iov.h"
  26 #include "qemu/sockets.h"
  27 #include "block/coroutine.h"
  28 #include "migration/migration.h"
  29 #include "migration/qemu-file.h"
  30 #include "migration/qemu-file-internal.h"
  31 #include "trace.h"
  32
  33 /*
  34  * Stop a file from being read/written - not all backing files can do this
  35  * typically only sockets can.
  36  */
  37 int qemu_file_shutdown(QEMUFile *f)
  38 {
  39     if (!f->ops->shut_down) {
  40         return -ENOSYS;
  41     }
  42     return f->ops->shut_down(f->opaque, true, true);
  43 }
  44
  45 bool qemu_file_mode_is_not_valid(const char *mode)
  46 {
  47     if (mode == NULL ||
  48         (mode[0] != 'r' && mode[0] != 'w') ||
  49         mode[1] != 'b' || mode[2] != 0) {
  50         fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
  51         return true;
  52     }
  53
  54     return false;
  55 }
  56
  57 QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
  58 {
  59     QEMUFile *f;
  60
  61     f = g_malloc0(sizeof(QEMUFile));
  62
  63     f->opaque = opaque;
  64     f->ops = ops;
  65     return f;
  66 }
  67
  68 /*
  69  * Get last error for stream f
  70  *
  71  * Return negative error value if there has been an error on previous
  72  * operations, return 0 if no error happened.
  73  *
  74  */
  75 int qemu_file_get_error(QEMUFile *f)
  76 {
  77     return f->last_error;
  78 }
  79
  80 void qemu_file_set_error(QEMUFile *f, int ret)
  81 {
  82     if (f->last_error == 0) {
  83         f->last_error = ret;
  84     }
  85 }
  86
  87 bool qemu_file_is_writable(QEMUFile *f)
  88 {
  89     return f->ops->writev_buffer || f->ops->put_buffer;
  90 }
  91
  92 /**
  93  * Flushes QEMUFile buffer
  94  *
  95  * If there is writev_buffer QEMUFileOps it uses it otherwise uses
  96  * put_buffer ops.
  97  */
  98 void qemu_fflush(QEMUFile *f)
  99 {
 100     ssize_t ret = 0;
 101
 102     if (!qemu_file_is_writable(f)) {
 103         return;
 104     }
 105
 106     if (f->ops->writev_buffer) {
 107         if (f->iovcnt > 0) {
 108             ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos);
 109         }
 110     } else {
 111         if (f->buf_index > 0) {
 112             ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index);
 113         }
 114     }
 115     if (ret >= 0) {
 116         f->pos += ret;
 117     }
 118     f->buf_index = 0;
 119     f->iovcnt = 0;
 120     if (ret < 0) {
 121         qemu_file_set_error(f, ret);
 122     }
 123 }
 124
 125 void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
 126 {
 127     int ret = 0;
 128
 129     if (f->ops->before_ram_iterate) {
 130         ret = f->ops->before_ram_iterate(f, f->opaque, flags);
 131         if (ret < 0) {
 132             qemu_file_set_error(f, ret);
 133         }
 134     }
 135 }
 136
 137 void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
 138 {
 139     int ret = 0;
 140
 141     if (f->ops->after_ram_iterate) {
 142         ret = f->ops->after_ram_iterate(f, f->opaque, flags);
 143         if (ret < 0) {
 144             qemu_file_set_error(f, ret);
 145         }
 146     }
 147 }
 148
 149 void ram_control_load_hook(QEMUFile *f, uint64_t flags)
 150 {
 151     int ret = -EINVAL;
 152
 153     if (f->ops->hook_ram_load) {
 154         ret = f->ops->hook_ram_load(f, f->opaque, flags);
 155         if (ret < 0) {
 156             qemu_file_set_error(f, ret);
 157         }
 158     } else {
 159         qemu_file_set_error(f, ret);
 160     }
 161 }
 162
 163 size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
 164                          ram_addr_t offset, size_t size, int *bytes_sent)
 165 {
 166     if (f->ops->save_page) {
 167         int ret = f->ops->save_page(f, f->opaque, block_offset,
 168                                     offset, size, bytes_sent);
 169
 170         if (ret != RAM_SAVE_CONTROL_DELAYED) {
 171             if (bytes_sent && *bytes_sent > 0) {
 172                 qemu_update_position(f, *bytes_sent);
 173             } else if (ret < 0) {
 174                 qemu_file_set_error(f, ret);
 175             }
 176         }
 177
 178         return ret;
 179     }
 180
 181     return RAM_SAVE_CONTROL_NOT_SUPP;
 182 }
 183
 184 /*
 185  * Attempt to fill the buffer from the underlying file
 186  * Returns the number of bytes read, or negative value for an error.
 187  *
 188  * Note that it can return a partially full buffer even in a not error/not EOF
 189  * case if the underlying file descriptor gives a short read, and that can
 190  * happen even on a blocking fd.
 191  */
 192 static ssize_t qemu_fill_buffer(QEMUFile *f)
 193 {
 194     int len;
 195     int pending;
 196
 197     assert(!qemu_file_is_writable(f));
 198
 199     pending = f->buf_size - f->buf_index;
 200     if (pending > 0) {
 201         memmove(f->buf, f->buf + f->buf_index, pending);
 202     }
 203     f->buf_index = 0;
 204     f->buf_size = pending;
 205
 206     len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
 207                         IO_BUF_SIZE - pending);
 208     if (len > 0) {
 209         f->buf_size += len;
 210         f->pos += len;
 211     } else if (len == 0) {
 212         qemu_file_set_error(f, -EIO);
 213     } else if (len != -EAGAIN) {
 214         qemu_file_set_error(f, len);
 215     }
 216
 217     return len;
 218 }
 219
 220 int qemu_get_fd(QEMUFile *f)
 221 {
 222     if (f->ops->get_fd) {
 223         return f->ops->get_fd(f->opaque);
 224     }
 225     return -1;
 226 }
 227
 228 void qemu_update_position(QEMUFile *f, size_t size)
 229 {
 230     f->pos += size;
 231 }
 232
 233 /** Closes the file
 234  *
 235  * Returns negative error value if any error happened on previous operations or
 236  * while closing the file. Returns 0 or positive number on success.
 237  *
 238  * The meaning of return value on success depends on the specific backend
 239  * being used.
 240  */
 241 int qemu_fclose(QEMUFile *f)
 242 {
 243     int ret;
 244     qemu_fflush(f);
 245     ret = qemu_file_get_error(f);
 246
 247     if (f->ops->close) {
 248         int ret2 = f->ops->close(f->opaque);
 249         if (ret >= 0) {
 250             ret = ret2;
 251         }
 252     }
 253     /* If any error was spotted before closing, we should report it
 254      * instead of the close() return value.
 255      */
 256     if (f->last_error) {
 257         ret = f->last_error;
 258     }
 259     g_free(f);
 260     trace_qemu_file_fclose();
 261     return ret;
 262 }
 263
 264 static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
 265 {
 266     /* check for adjacent buffer and coalesce them */
 267     if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
 268         f->iov[f->iovcnt - 1].iov_len) {
 269         f->iov[f->iovcnt - 1].iov_len += size;
 270     } else {
 271         f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
 272         f->iov[f->iovcnt++].iov_len = size;
 273     }
 274
 275     if (f->iovcnt >= MAX_IOV_SIZE) {
 276         qemu_fflush(f);
 277     }
 278 }
 279
 280 void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
 281 {
 282     if (!f->ops->writev_buffer) {
 283         qemu_put_buffer(f, buf, size);
 284         return;
 285     }
 286
 287     if (f->last_error) {
 288         return;
 289     }
 290
 291     f->bytes_xfer += size;
 292     add_to_iovec(f, buf, size);
 293 }
 294
 295 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
 296 {
 297     int l;
 298
 299     if (f->last_error) {
 300         return;
 301     }
 302
 303     while (size > 0) {
 304         l = IO_BUF_SIZE - f->buf_index;
 305         if (l > size) {
 306             l = size;
 307         }
 308         memcpy(f->buf + f->buf_index, buf, l);
 309         f->bytes_xfer += l;
 310         if (f->ops->writev_buffer) {
 311             add_to_iovec(f, f->buf + f->buf_index, l);
 312         }
 313         f->buf_index += l;
 314         if (f->buf_index == IO_BUF_SIZE) {
 315             qemu_fflush(f);
 316         }
 317         if (qemu_file_get_error(f)) {
 318             break;
 319         }
 320         buf += l;
 321         size -= l;
 322     }
 323 }
 324
 325 void qemu_put_byte(QEMUFile *f, int v)
 326 {
 327     if (f->last_error) {
 328         return;
 329     }
 330
 331     f->buf[f->buf_index] = v;
 332     f->bytes_xfer++;
 333     if (f->ops->writev_buffer) {
 334         add_to_iovec(f, f->buf + f->buf_index, 1);
 335     }
 336     f->buf_index++;
 337     if (f->buf_index == IO_BUF_SIZE) {
 338         qemu_fflush(f);
 339     }
 340 }
 341
 342 void qemu_file_skip(QEMUFile *f, int size)
 343 {
 344     if (f->buf_index + size <= f->buf_size) {
 345         f->buf_index += size;
 346     }
 347 }
 348
 349 /*
 350  * Read 'size' bytes from file (at 'offset') into buf without moving the
 351  * pointer.
 352  *
 353  * It will return size bytes unless there was an error, in which case it will
 354  * return as many as it managed to read (assuming blocking fd's which
 355  * all current QEMUFile are)
 356  */
 357 int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset)
 358 {
 359     int pending;
 360     int index;
 361
 362     assert(!qemu_file_is_writable(f));
 363     assert(offset < IO_BUF_SIZE);
 364     assert(size <= IO_BUF_SIZE - offset);
 365
 366     /* The 1st byte to read from */
 367     index = f->buf_index + offset;
 368     /* The number of available bytes starting at index */
 369     pending = f->buf_size - index;
 370
 371     /*
 372      * qemu_fill_buffer might return just a few bytes, even when there isn't
 373      * an error, so loop collecting them until we get enough.
 374      */
 375     while (pending < size) {
 376         int received = qemu_fill_buffer(f);
 377
 378         if (received <= 0) {
 379             break;
 380         }
 381
 382         index = f->buf_index + offset;
 383         pending = f->buf_size - index;
 384     }
 385
 386     if (pending <= 0) {
 387         return 0;
 388     }
 389     if (size > pending) {
 390         size = pending;
 391     }
 392
 393     memcpy(buf, f->buf + index, size);
 394     return size;
 395 }
 396
 397 /*
 398  * Read 'size' bytes of data from the file into buf.
 399  * 'size' can be larger than the internal buffer.
 400  *
 401  * It will return size bytes unless there was an error, in which case it will
 402  * return as many as it managed to read (assuming blocking fd's which
 403  * all current QEMUFile are)
 404  */
 405 int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size)
 406 {
 407     int pending = size;
 408     int done = 0;
 409
 410     while (pending > 0) {
 411         int res;
 412
 413         res = qemu_peek_buffer(f, buf, MIN(pending, IO_BUF_SIZE), 0);
 414         if (res == 0) {
 415             return done;
 416         }
 417         qemu_file_skip(f, res);
 418         buf += res;
 419         pending -= res;
 420         done += res;
 421     }
 422     return done;
 423 }
 424
 425 /*
 426  * Peeks a single byte from the buffer; this isn't guaranteed to work if
 427  * offset leaves a gap after the previous read/peeked data.
 428  */
 429 int qemu_peek_byte(QEMUFile *f, int offset)
 430 {
 431     int index = f->buf_index + offset;
 432
 433     assert(!qemu_file_is_writable(f));
 434     assert(offset < IO_BUF_SIZE);
 435
 436     if (index >= f->buf_size) {
 437         qemu_fill_buffer(f);
 438         index = f->buf_index + offset;
 439         if (index >= f->buf_size) {
 440             return 0;
 441         }
 442     }
 443     return f->buf[index];
 444 }
 445
 446 int qemu_get_byte(QEMUFile *f)
 447 {
 448     int result;
 449
 450     result = qemu_peek_byte(f, 0);
 451     qemu_file_skip(f, 1);
 452     return result;
 453 }
 454
 455 int64_t qemu_ftell(QEMUFile *f)
 456 {
 457     qemu_fflush(f);
 458     return f->pos;
 459 }
 460
 461 int qemu_file_rate_limit(QEMUFile *f)
 462 {
 463     if (qemu_file_get_error(f)) {
 464         return 1;
 465     }
 466     if (f->xfer_limit > 0 && f->bytes_xfer > f->xfer_limit) {
 467         return 1;
 468     }
 469     return 0;
 470 }
 471
 472 int64_t qemu_file_get_rate_limit(QEMUFile *f)
 473 {
 474     return f->xfer_limit;
 475 }
 476
 477 void qemu_file_set_rate_limit(QEMUFile *f, int64_t limit)
 478 {
 479     f->xfer_limit = limit;
 480 }
 481
 482 void qemu_file_reset_rate_limit(QEMUFile *f)
 483 {
 484     f->bytes_xfer = 0;
 485 }
 486
 487 void qemu_put_be16(QEMUFile *f, unsigned int v)
 488 {
 489     qemu_put_byte(f, v >> 8);
 490     qemu_put_byte(f, v);
 491 }
 492
 493 void qemu_put_be32(QEMUFile *f, unsigned int v)
 494 {
 495     qemu_put_byte(f, v >> 24);
 496     qemu_put_byte(f, v >> 16);
 497     qemu_put_byte(f, v >> 8);
 498     qemu_put_byte(f, v);
 499 }
 500
 501 void qemu_put_be64(QEMUFile *f, uint64_t v)
 502 {
 503     qemu_put_be32(f, v >> 32);
 504     qemu_put_be32(f, v);
 505 }
 506
 507 unsigned int qemu_get_be16(QEMUFile *f)
 508 {
 509     unsigned int v;
 510     v = qemu_get_byte(f) << 8;
 511     v |= qemu_get_byte(f);
 512     return v;
 513 }
 514
 515 unsigned int qemu_get_be32(QEMUFile *f)
 516 {
 517     unsigned int v;
 518     v = (unsigned int)qemu_get_byte(f) << 24;
 519     v |= qemu_get_byte(f) << 16;
 520     v |= qemu_get_byte(f) << 8;
 521     v |= qemu_get_byte(f);
 522     return v;
 523 }
 524
 525 uint64_t qemu_get_be64(QEMUFile *f)
 526 {
 527     uint64_t v;
 528     v = (uint64_t)qemu_get_be32(f) << 32;
 529     v |= qemu_get_be32(f);
 530     return v;
 531 }