util/osdep.c

   1 /*
   2  * QEMU low level functions
   3  *
   4  * Copyright (c) 2003 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/osdep.h"
  25 #include "qapi/error.h"
  26 #include "qemu/cutils.h"
  27 #include "qemu/sockets.h"
  28 #include "qemu/error-report.h"
  29 #include "qemu/madvise.h"
  30 #include "qemu/mprotect.h"
  31 #include "qemu/hw-version.h"
  32 #include "monitor/monitor.h"
  33
  34 static const char *hw_version = QEMU_HW_VERSION;
  35
  36 int socket_set_cork(int fd, int v)
  37 {
  38 #if defined(SOL_TCP) && defined(TCP_CORK)
  39     return setsockopt(fd, SOL_TCP, TCP_CORK, &v, sizeof(v));
  40 #else
  41     return 0;
  42 #endif
  43 }
  44
  45 int socket_set_nodelay(int fd)
  46 {
  47     int v = 1;
  48     return setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &v, sizeof(v));
  49 }
  50
  51 int qemu_madvise(void *addr, size_t len, int advice)
  52 {
  53     if (advice == QEMU_MADV_INVALID) {
  54         errno = EINVAL;
  55         return -1;
  56     }
  57 #if defined(CONFIG_MADVISE)
  58     return madvise(addr, len, advice);
  59 #elif defined(CONFIG_POSIX_MADVISE)
  60     int rc = posix_madvise(addr, len, advice);
  61     if (rc) {
  62         errno = rc;
  63         return -1;
  64     }
  65     return 0;
  66 #else
  67     errno = ENOSYS;
  68     return -1;
  69 #endif
  70 }
  71
  72 static int qemu_mprotect__osdep(void *addr, size_t size, int prot)
  73 {
  74     g_assert(!((uintptr_t)addr & ~qemu_real_host_page_mask()));
  75     g_assert(!(size & ~qemu_real_host_page_mask()));
  76
  77 #ifdef _WIN32
  78     DWORD old_protect;
  79
  80     if (!VirtualProtect(addr, size, prot, &old_protect)) {
  81         g_autofree gchar *emsg = g_win32_error_message(GetLastError());
  82         error_report("%s: VirtualProtect failed: %s", __func__, emsg);
  83         return -1;
  84     }
  85     return 0;
  86 #else
  87     if (mprotect(addr, size, prot)) {
  88         error_report("%s: mprotect failed: %s", __func__, strerror(errno));
  89         return -1;
  90     }
  91     return 0;
  92 #endif
  93 }
  94
  95 int qemu_mprotect_rw(void *addr, size_t size)
  96 {
  97 #ifdef _WIN32
  98     return qemu_mprotect__osdep(addr, size, PAGE_READWRITE);
  99 #else
 100     return qemu_mprotect__osdep(addr, size, PROT_READ | PROT_WRITE);
 101 #endif
 102 }
 103
 104 int qemu_mprotect_rwx(void *addr, size_t size)
 105 {
 106 #ifdef _WIN32
 107     return qemu_mprotect__osdep(addr, size, PAGE_EXECUTE_READWRITE);
 108 #else
 109     return qemu_mprotect__osdep(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC);
 110 #endif
 111 }
 112
 113 int qemu_mprotect_none(void *addr, size_t size)
 114 {
 115 #ifdef _WIN32
 116     return qemu_mprotect__osdep(addr, size, PAGE_NOACCESS);
 117 #else
 118     return qemu_mprotect__osdep(addr, size, PROT_NONE);
 119 #endif
 120 }
 121
 122 #ifndef _WIN32
 123
 124 static int fcntl_op_setlk = -1;
 125 static int fcntl_op_getlk = -1;
 126
 127 /*
 128  * Dups an fd and sets the flags
 129  */
 130 int qemu_dup_flags(int fd, int flags)
 131 {
 132     int ret;
 133     int serrno;
 134     int dup_flags;
 135
 136     ret = qemu_dup(fd);
 137     if (ret == -1) {
 138         goto fail;
 139     }
 140
 141     dup_flags = fcntl(ret, F_GETFL);
 142     if (dup_flags == -1) {
 143         goto fail;
 144     }
 145
 146     if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
 147         errno = EINVAL;
 148         goto fail;
 149     }
 150
 151     /* Set/unset flags that we can with fcntl */
 152     if (fcntl(ret, F_SETFL, flags) == -1) {
 153         goto fail;
 154     }
 155
 156     /* Truncate the file in the cases that open() would truncate it */
 157     if (flags & O_TRUNC ||
 158             ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
 159         if (ftruncate(ret, 0) == -1) {
 160             goto fail;
 161         }
 162     }
 163
 164     return ret;
 165
 166 fail:
 167     serrno = errno;
 168     if (ret != -1) {
 169         close(ret);
 170     }
 171     errno = serrno;
 172     return -1;
 173 }
 174
 175 int qemu_dup(int fd)
 176 {
 177     int ret;
 178 #ifdef F_DUPFD_CLOEXEC
 179     ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
 180 #else
 181     ret = dup(fd);
 182     if (ret != -1) {
 183         qemu_set_cloexec(ret);
 184     }
 185 #endif
 186     return ret;
 187 }
 188
 189 static int qemu_parse_fdset(const char *param)
 190 {
 191     return qemu_parse_fd(param);
 192 }
 193
 194 static void qemu_probe_lock_ops(void)
 195 {
 196     if (fcntl_op_setlk == -1) {
 197 #ifdef F_OFD_SETLK
 198         int fd;
 199         int ret;
 200         struct flock fl = {
 201             .l_whence = SEEK_SET,
 202             .l_start  = 0,
 203             .l_len    = 0,
 204             .l_type   = F_WRLCK,
 205         };
 206
 207         fd = open("/dev/null", O_RDWR);
 208         if (fd < 0) {
 209             fprintf(stderr,
 210                     "Failed to open /dev/null for OFD lock probing: %s\n",
 211                     strerror(errno));
 212             fcntl_op_setlk = F_SETLK;
 213             fcntl_op_getlk = F_GETLK;
 214             return;
 215         }
 216         ret = fcntl(fd, F_OFD_GETLK, &fl);
 217         close(fd);
 218         if (!ret) {
 219             fcntl_op_setlk = F_OFD_SETLK;
 220             fcntl_op_getlk = F_OFD_GETLK;
 221         } else {
 222             fcntl_op_setlk = F_SETLK;
 223             fcntl_op_getlk = F_GETLK;
 224         }
 225 #else
 226         fcntl_op_setlk = F_SETLK;
 227         fcntl_op_getlk = F_GETLK;
 228 #endif
 229     }
 230 }
 231
 232 bool qemu_has_ofd_lock(void)
 233 {
 234     qemu_probe_lock_ops();
 235 #ifdef F_OFD_SETLK
 236     return fcntl_op_setlk == F_OFD_SETLK;
 237 #else
 238     return false;
 239 #endif
 240 }
 241
 242 static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
 243 {
 244     int ret;
 245     struct flock fl = {
 246         .l_whence = SEEK_SET,
 247         .l_start  = start,
 248         .l_len    = len,
 249         .l_type   = fl_type,
 250     };
 251     qemu_probe_lock_ops();
 252     ret = RETRY_ON_EINTR(fcntl(fd, fcntl_op_setlk, &fl));
 253     return ret == -1 ? -errno : 0;
 254 }
 255
 256 int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive)
 257 {
 258     return qemu_lock_fcntl(fd, start, len, exclusive ? F_WRLCK : F_RDLCK);
 259 }
 260
 261 int qemu_unlock_fd(int fd, int64_t start, int64_t len)
 262 {
 263     return qemu_lock_fcntl(fd, start, len, F_UNLCK);
 264 }
 265
 266 int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive)
 267 {
 268     int ret;
 269     struct flock fl = {
 270         .l_whence = SEEK_SET,
 271         .l_start  = start,
 272         .l_len    = len,
 273         .l_type   = exclusive ? F_WRLCK : F_RDLCK,
 274     };
 275     qemu_probe_lock_ops();
 276     ret = fcntl(fd, fcntl_op_getlk, &fl);
 277     if (ret == -1) {
 278         return -errno;
 279     } else {
 280         return fl.l_type == F_UNLCK ? 0 : -EAGAIN;
 281     }
 282 }
 283 #endif
 284
 285 bool qemu_has_direct_io(void)
 286 {
 287 #ifdef O_DIRECT
 288     return true;
 289 #else
 290     return false;
 291 #endif
 292 }
 293
 294 static int qemu_open_cloexec(const char *name, int flags, mode_t mode)
 295 {
 296     int ret;
 297 #ifdef O_CLOEXEC
 298     ret = open(name, flags | O_CLOEXEC, mode);
 299 #else
 300     ret = open(name, flags, mode);
 301     if (ret >= 0) {
 302         qemu_set_cloexec(ret);
 303     }
 304 #endif
 305     return ret;
 306 }
 307
 308 /*
 309  * Opens a file with FD_CLOEXEC set
 310  */
 311 static int
 312 qemu_open_internal(const char *name, int flags, mode_t mode, Error **errp)
 313 {
 314     int ret;
 315
 316 #ifndef _WIN32
 317     const char *fdset_id_str;
 318
 319     /* Attempt dup of fd from fd set */
 320     if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
 321         int64_t fdset_id;
 322
 323         fdset_id = qemu_parse_fdset(fdset_id_str);
 324         if (fdset_id == -1) {
 325             error_setg(errp, "Could not parse fdset %s", name);
 326             errno = EINVAL;
 327             return -1;
 328         }
 329
 330         return monitor_fdset_dup_fd_add(fdset_id, flags, errp);
 331     }
 332 #endif
 333
 334     ret = qemu_open_cloexec(name, flags, mode);
 335
 336     if (ret == -1) {
 337         const char *action = flags & O_CREAT ? "create" : "open";
 338 #ifdef O_DIRECT
 339         /* Give more helpful error message for O_DIRECT */
 340         if (errno == EINVAL && (flags & O_DIRECT)) {
 341             ret = open(name, flags & ~O_DIRECT, mode);
 342             if (ret != -1) {
 343                 close(ret);
 344                 error_setg(errp, "Could not %s '%s': "
 345                            "filesystem does not support O_DIRECT",
 346                            action, name);
 347                 errno = EINVAL; /* restore first open()'s errno */
 348                 return -1;
 349             }
 350         }
 351 #endif /* O_DIRECT */
 352         error_setg_errno(errp, errno, "Could not %s '%s'",
 353                          action, name);
 354     }
 355
 356     return ret;
 357 }
 358
 359
 360 int qemu_open(const char *name, int flags, Error **errp)
 361 {
 362     assert(!(flags & O_CREAT));
 363
 364     return qemu_open_internal(name, flags, 0, errp);
 365 }
 366
 367
 368 int qemu_create(const char *name, int flags, mode_t mode, Error **errp)
 369 {
 370     assert(!(flags & O_CREAT));
 371
 372     return qemu_open_internal(name, flags | O_CREAT, mode, errp);
 373 }
 374
 375
 376 int qemu_open_old(const char *name, int flags, ...)
 377 {
 378     va_list ap;
 379     mode_t mode = 0;
 380     int ret;
 381
 382     va_start(ap, flags);
 383     if (flags & O_CREAT) {
 384         mode = va_arg(ap, int);
 385     }
 386     va_end(ap);
 387
 388     ret = qemu_open_internal(name, flags, mode, NULL);
 389
 390 #ifdef O_DIRECT
 391     if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
 392         error_report("file system may not support O_DIRECT");
 393         errno = EINVAL; /* in case it was clobbered */
 394     }
 395 #endif /* O_DIRECT */
 396
 397     return ret;
 398 }
 399
 400 int qemu_close(int fd)
 401 {
 402     /* Close fd that was dup'd from an fdset */
 403     monitor_fdset_dup_fd_remove(fd);
 404     return close(fd);
 405 }
 406
 407 /*
 408  * Delete a file from the filesystem, unless the filename is /dev/fdset/...
 409  *
 410  * Returns: On success, zero is returned.  On error, -1 is returned,
 411  * and errno is set appropriately.
 412  */
 413 int qemu_unlink(const char *name)
 414 {
 415     if (g_str_has_prefix(name, "/dev/fdset/")) {
 416         return 0;
 417     }
 418
 419     return unlink(name);
 420 }
 421
 422 /*
 423  * A variant of write(2) which handles partial write.
 424  *
 425  * Return the number of bytes transferred.
 426  * Set errno if fewer than `count' bytes are written.
 427  *
 428  * This function don't work with non-blocking fd's.
 429  * Any of the possibilities with non-blocking fd's is bad:
 430  *   - return a short write (then name is wrong)
 431  *   - busy wait adding (errno == EAGAIN) to the loop
 432  */
 433 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 434 {
 435     ssize_t ret = 0;
 436     ssize_t total = 0;
 437
 438     while (count) {
 439         ret = write(fd, buf, count);
 440         if (ret < 0) {
 441             if (errno == EINTR)
 442                 continue;
 443             break;
 444         }
 445
 446         count -= ret;
 447         buf += ret;
 448         total += ret;
 449     }
 450
 451     return total;
 452 }
 453
 454 /*
 455  * Opens a socket with FD_CLOEXEC set
 456  */
 457 int qemu_socket(int domain, int type, int protocol)
 458 {
 459     int ret;
 460
 461 #ifdef SOCK_CLOEXEC
 462     ret = socket(domain, type | SOCK_CLOEXEC, protocol);
 463     if (ret != -1 || errno != EINVAL) {
 464         return ret;
 465     }
 466 #endif
 467     ret = socket(domain, type, protocol);
 468     if (ret >= 0) {
 469         qemu_set_cloexec(ret);
 470     }
 471
 472     return ret;
 473 }
 474
 475 /*
 476  * Accept a connection and set FD_CLOEXEC
 477  */
 478 int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
 479 {
 480     int ret;
 481
 482 #ifdef CONFIG_ACCEPT4
 483     ret = accept4(s, addr, addrlen, SOCK_CLOEXEC);
 484     if (ret != -1 || errno != ENOSYS) {
 485         return ret;
 486     }
 487 #endif
 488     ret = accept(s, addr, addrlen);
 489     if (ret >= 0) {
 490         qemu_set_cloexec(ret);
 491     }
 492
 493     return ret;
 494 }
 495
 496 ssize_t qemu_send_full(int s, const void *buf, size_t count)
 497 {
 498     ssize_t ret = 0;
 499     ssize_t total = 0;
 500
 501     while (count) {
 502         ret = send(s, buf, count, 0);
 503         if (ret < 0) {
 504             if (errno == EINTR) {
 505                 continue;
 506             }
 507             break;
 508         }
 509
 510         count -= ret;
 511         buf += ret;
 512         total += ret;
 513     }
 514
 515     return total;
 516 }
 517
 518 void qemu_set_hw_version(const char *version)
 519 {
 520     hw_version = version;
 521 }
 522
 523 const char *qemu_hw_version(void)
 524 {
 525     return hw_version;
 526 }
 527
 528 #ifdef _WIN32
 529 static void socket_cleanup(void)
 530 {
 531     WSACleanup();
 532 }
 533 #endif
 534
 535 int socket_init(void)
 536 {
 537 #ifdef _WIN32
 538     WSADATA Data;
 539     int ret, err;
 540
 541     ret = WSAStartup(MAKEWORD(2, 2), &Data);
 542     if (ret != 0) {
 543         err = WSAGetLastError();
 544         fprintf(stderr, "WSAStartup: %d\n", err);
 545         return -1;
 546     }
 547     atexit(socket_cleanup);
 548 #endif
 549     return 0;
 550 }
 551
 552
 553 #ifndef CONFIG_IOVEC
 554 static ssize_t
 555 readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write)
 556 {
 557     unsigned i = 0;
 558     ssize_t ret = 0;
 559     ssize_t off = 0;
 560     while (i < iov_cnt) {
 561         ssize_t r = do_write
 562             ? write(fd, iov[i].iov_base + off, iov[i].iov_len - off)
 563             : read(fd, iov[i].iov_base + off, iov[i].iov_len - off);
 564         if (r > 0) {
 565             ret += r;
 566             off += r;
 567             if (off < iov[i].iov_len) {
 568                 continue;
 569             }
 570         } else if (!r) {
 571             break;
 572         } else if (errno == EINTR) {
 573             continue;
 574         } else {
 575             /* else it is some "other" error,
 576              * only return if there was no data processed. */
 577             if (ret == 0) {
 578                 ret = -1;
 579             }
 580             break;
 581         }
 582         off = 0;
 583         i++;
 584     }
 585     return ret;
 586 }
 587
 588 ssize_t
 589 readv(int fd, const struct iovec *iov, int iov_cnt)
 590 {
 591     return readv_writev(fd, iov, iov_cnt, false);
 592 }
 593
 594 ssize_t
 595 writev(int fd, const struct iovec *iov, int iov_cnt)
 596 {
 597     return readv_writev(fd, iov, iov_cnt, true);
 598 }
 599 #endif
 600
 601 /*
 602  * Make sure data goes on disk, but if possible do not bother to
 603  * write out the inode just for timestamp updates.
 604  *
 605  * Unfortunately even in 2009 many operating systems do not support
 606  * fdatasync and have to fall back to fsync.
 607  */
 608 int qemu_fdatasync(int fd)
 609 {
 610 #ifdef CONFIG_FDATASYNC
 611     return fdatasync(fd);
 612 #else
 613     return fsync(fd);
 614 #endif
 615 }