nix/fcntl.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427
//! file control options
use crate::errno::Errno;
#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
use core::slice;
use libc::{c_int, c_uint, size_t, ssize_t};
#[cfg(any(
target_os = "netbsd",
apple_targets,
target_os = "dragonfly",
all(target_os = "freebsd", target_arch = "x86_64"),
))]
use std::ffi::CStr;
use std::ffi::OsString;
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
use std::ops::{Deref, DerefMut};
#[cfg(not(target_os = "redox"))]
use std::os::raw;
use std::os::unix::ffi::OsStringExt;
use std::os::unix::io::RawFd;
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
use std::os::unix::io::{AsRawFd, OwnedFd};
#[cfg(any(
target_os = "netbsd",
apple_targets,
target_os = "dragonfly",
all(target_os = "freebsd", target_arch = "x86_64"),
))]
use std::path::PathBuf;
#[cfg(any(linux_android, target_os = "freebsd"))]
use std::{os::unix::io::AsFd, ptr};
#[cfg(feature = "fs")]
use crate::{sys::stat::Mode, NixPath, Result};
#[cfg(any(
linux_android,
target_os = "emscripten",
target_os = "fuchsia",
target_os = "wasi",
target_env = "uclibc",
target_os = "freebsd"
))]
#[cfg(feature = "fs")]
pub use self::posix_fadvise::{posix_fadvise, PosixFadviseAdvice};
#[cfg(not(target_os = "redox"))]
#[cfg(any(feature = "fs", feature = "process", feature = "user"))]
libc_bitflags! {
/// Flags that control how the various *at syscalls behave.
#[cfg_attr(docsrs, doc(cfg(any(feature = "fs", feature = "process"))))]
pub struct AtFlags: c_int {
#[allow(missing_docs)]
#[doc(hidden)]
// Should not be used by the public API, but only internally.
AT_REMOVEDIR;
/// Used with [`linkat`](crate::unistd::linkat`) to create a link to a symbolic link's
/// target, instead of to the symbolic link itself.
AT_SYMLINK_FOLLOW;
/// Used with functions like [`fstatat`](crate::sys::stat::fstatat`) to operate on a link
/// itself, instead of the symbolic link's target.
AT_SYMLINK_NOFOLLOW;
/// Don't automount the terminal ("basename") component of pathname if it is a directory
/// that is an automount point.
#[cfg(linux_android)]
AT_NO_AUTOMOUNT;
/// If the provided path is an empty string, operate on the provided directory file
/// descriptor instead.
#[cfg(any(linux_android, target_os = "freebsd", target_os = "hurd"))]
AT_EMPTY_PATH;
/// Used with [`faccessat`](crate::unistd::faccessat), the checks for accessibility are
/// performed using the effective user and group IDs instead of the real user and group ID
#[cfg(not(target_os = "android"))]
AT_EACCESS;
}
}
#[cfg(any(
feature = "fs",
feature = "term",
all(feature = "fanotify", target_os = "linux")
))]
libc_bitflags!(
/// Configuration options for opened files.
#[cfg_attr(docsrs, doc(cfg(any(feature = "fs", feature = "term", all(feature = "fanotify", target_os = "linux")))))]
pub struct OFlag: c_int {
/// Mask for the access mode of the file.
O_ACCMODE;
/// Use alternate I/O semantics.
#[cfg(target_os = "netbsd")]
O_ALT_IO;
/// Open the file in append-only mode.
O_APPEND;
/// Generate a signal when input or output becomes possible.
#[cfg(not(any(
solarish,
target_os = "aix",
target_os = "haiku"
)))]
O_ASYNC;
/// Closes the file descriptor once an `execve` call is made.
///
/// Also sets the file offset to the beginning of the file.
O_CLOEXEC;
/// Create the file if it does not exist.
O_CREAT;
/// Try to minimize cache effects of the I/O for this file.
#[cfg(any(
freebsdlike,
linux_android,
solarish,
target_os = "netbsd"
))]
O_DIRECT;
/// If the specified path isn't a directory, fail.
O_DIRECTORY;
/// Implicitly follow each `write()` with an `fdatasync()`.
#[cfg(any(linux_android, apple_targets, target_os = "freebsd", netbsdlike))]
O_DSYNC;
/// Error out if a file was not created.
O_EXCL;
/// Open for execute only.
#[cfg(target_os = "freebsd")]
O_EXEC;
/// Open with an exclusive file lock.
#[cfg(any(bsd, target_os = "redox"))]
O_EXLOCK;
/// Same as `O_SYNC`.
#[cfg(any(bsd,
all(target_os = "linux", not(target_env = "musl"), not(target_env = "ohos")),
target_os = "redox"))]
O_FSYNC;
/// Allow files whose sizes can't be represented in an `off_t` to be opened.
#[cfg(linux_android)]
O_LARGEFILE;
/// Do not update the file last access time during `read(2)`s.
#[cfg(linux_android)]
O_NOATIME;
/// Don't attach the device as the process' controlling terminal.
#[cfg(not(target_os = "redox"))]
O_NOCTTY;
/// Same as `O_NONBLOCK`.
#[cfg(not(any(target_os = "redox", target_os = "haiku")))]
O_NDELAY;
/// `open()` will fail if the given path is a symbolic link.
O_NOFOLLOW;
/// When possible, open the file in nonblocking mode.
O_NONBLOCK;
/// Don't deliver `SIGPIPE`.
#[cfg(target_os = "netbsd")]
O_NOSIGPIPE;
/// Obtain a file descriptor for low-level access.
///
/// The file itself is not opened and other file operations will fail.
#[cfg(any(linux_android, target_os = "redox", target_os = "freebsd", target_os = "fuchsia"))]
O_PATH;
/// Only allow reading.
///
/// This should not be combined with `O_WRONLY` or `O_RDWR`.
O_RDONLY;
/// Allow both reading and writing.
///
/// This should not be combined with `O_WRONLY` or `O_RDONLY`.
O_RDWR;
/// Similar to `O_DSYNC` but applies to `read`s instead.
#[cfg(any(target_os = "linux", netbsdlike))]
O_RSYNC;
/// Open directory for search only. Skip search permission checks on
/// later `openat()` calls using the obtained file descriptor.
#[cfg(any(
apple_targets,
solarish,
target_os = "netbsd",
target_os = "freebsd",
target_os = "fuchsia",
target_os = "emscripten",
target_os = "aix",
target_os = "wasi"
))]
O_SEARCH;
/// Open with a shared file lock.
#[cfg(any(bsd, target_os = "redox"))]
O_SHLOCK;
/// Implicitly follow each `write()` with an `fsync()`.
#[cfg(not(target_os = "redox"))]
O_SYNC;
/// Create an unnamed temporary file.
#[cfg(linux_android)]
O_TMPFILE;
/// Truncate an existing regular file to 0 length if it allows writing.
O_TRUNC;
/// Restore default TTY attributes.
#[cfg(target_os = "freebsd")]
O_TTY_INIT;
/// Only allow writing.
///
/// This should not be combined with `O_RDONLY` or `O_RDWR`.
O_WRONLY;
}
);
/// Computes the raw fd consumed by a function of the form `*at`.
#[cfg(any(
all(feature = "fs", not(target_os = "redox")),
all(feature = "process", linux_android),
all(feature = "fanotify", target_os = "linux")
))]
pub(crate) fn at_rawfd(fd: Option<RawFd>) -> raw::c_int {
fd.unwrap_or(libc::AT_FDCWD)
}
feature! {
#![feature = "fs"]
/// open or create a file for reading, writing or executing
///
/// # See Also
/// [`open`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html)
// The conversion is not identical on all operating systems.
#[allow(clippy::useless_conversion)]
pub fn open<P: ?Sized + NixPath>(
path: &P,
oflag: OFlag,
mode: Mode,
) -> Result<RawFd> {
let fd = path.with_nix_path(|cstr| unsafe {
libc::open(cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint)
})?;
Errno::result(fd)
}
/// open or create a file for reading, writing or executing
///
/// The `openat` function is equivalent to the [`open`] function except in the case where the path
/// specifies a relative path. In that case, the file to be opened is determined relative to the
/// directory associated with the file descriptor `fd`.
///
/// # See Also
/// [`openat`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/openat.html)
// The conversion is not identical on all operating systems.
#[allow(clippy::useless_conversion)]
#[cfg(not(target_os = "redox"))]
pub fn openat<P: ?Sized + NixPath>(
dirfd: Option<RawFd>,
path: &P,
oflag: OFlag,
mode: Mode,
) -> Result<RawFd> {
let fd = path.with_nix_path(|cstr| unsafe {
libc::openat(at_rawfd(dirfd), cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint)
})?;
Errno::result(fd)
}
cfg_if::cfg_if! {
if #[cfg(target_os = "linux")] {
libc_bitflags! {
/// Path resolution flags.
///
/// See [path resolution(7)](https://man7.org/linux/man-pages/man7/path_resolution.7.html)
/// for details of the resolution process.
pub struct ResolveFlag: libc::c_ulonglong {
/// Do not permit the path resolution to succeed if any component of
/// the resolution is not a descendant of the directory indicated by
/// dirfd. This causes absolute symbolic links (and absolute values of
/// pathname) to be rejected.
RESOLVE_BENEATH;
/// Treat the directory referred to by dirfd as the root directory
/// while resolving pathname.
RESOLVE_IN_ROOT;
/// Disallow all magic-link resolution during path resolution. Magic
/// links are symbolic link-like objects that are most notably found
/// in proc(5); examples include `/proc/[pid]/exe` and `/proc/[pid]/fd/*`.
///
/// See symlink(7) for more details.
RESOLVE_NO_MAGICLINKS;
/// Disallow resolution of symbolic links during path resolution. This
/// option implies RESOLVE_NO_MAGICLINKS.
RESOLVE_NO_SYMLINKS;
/// Disallow traversal of mount points during path resolution (including
/// all bind mounts).
RESOLVE_NO_XDEV;
}
}
/// Specifies how [openat2] should open a pathname.
///
/// See <https://man7.org/linux/man-pages/man2/open_how.2type.html>
#[repr(transparent)]
#[derive(Clone, Copy, Debug)]
pub struct OpenHow(libc::open_how);
impl OpenHow {
/// Create a new zero-filled `open_how`.
pub fn new() -> Self {
// safety: according to the man page, open_how MUST be zero-initialized
// on init so that unknown fields are also zeroed.
Self(unsafe {
std::mem::MaybeUninit::zeroed().assume_init()
})
}
/// Set the open flags used to open a file, completely overwriting any
/// existing flags.
pub fn flags(mut self, flags: OFlag) -> Self {
let flags = flags.bits() as libc::c_ulonglong;
self.0.flags = flags;
self
}
/// Set the file mode new files will be created with, overwriting any
/// existing flags.
pub fn mode(mut self, mode: Mode) -> Self {
let mode = mode.bits() as libc::c_ulonglong;
self.0.mode = mode;
self
}
/// Set resolve flags, completely overwriting any existing flags.
///
/// See [ResolveFlag] for more detail.
pub fn resolve(mut self, resolve: ResolveFlag) -> Self {
let resolve = resolve.bits();
self.0.resolve = resolve;
self
}
}
// safety: default isn't derivable because libc::open_how must be zeroed
impl Default for OpenHow {
fn default() -> Self {
Self::new()
}
}
/// Open or create a file for reading, writing or executing.
///
/// `openat2` is an extension of the [`openat`] function that allows the caller
/// to control how path resolution happens.
///
/// # See also
///
/// [openat2](https://man7.org/linux/man-pages/man2/openat2.2.html)
pub fn openat2<P: ?Sized + NixPath>(
dirfd: RawFd,
path: &P,
mut how: OpenHow,
) -> Result<RawFd> {
let fd = path.with_nix_path(|cstr| unsafe {
libc::syscall(
libc::SYS_openat2,
dirfd,
cstr.as_ptr(),
&mut how as *mut OpenHow,
std::mem::size_of::<libc::open_how>(),
)
})?;
Errno::result(fd as RawFd)
}
}
}
/// Change the name of a file.
///
/// The `renameat` function is equivalent to `rename` except in the case where either `old_path`
/// or `new_path` specifies a relative path. In such cases, the file to be renamed (or the its new
/// name, respectively) is located relative to `old_dirfd` or `new_dirfd`, respectively
///
/// # See Also
/// [`renameat`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/rename.html)
#[cfg(not(target_os = "redox"))]
pub fn renameat<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(
old_dirfd: Option<RawFd>,
old_path: &P1,
new_dirfd: Option<RawFd>,
new_path: &P2,
) -> Result<()> {
let res = old_path.with_nix_path(|old_cstr| {
new_path.with_nix_path(|new_cstr| unsafe {
libc::renameat(
at_rawfd(old_dirfd),
old_cstr.as_ptr(),
at_rawfd(new_dirfd),
new_cstr.as_ptr(),
)
})
})??;
Errno::result(res).map(drop)
}
}
#[cfg(all(target_os = "linux", target_env = "gnu"))]
#[cfg(feature = "fs")]
libc_bitflags! {
/// Flags for use with [`renameat2`].
#[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
pub struct RenameFlags: u32 {
/// Atomically exchange `old_path` and `new_path`.
RENAME_EXCHANGE;
/// Don't overwrite `new_path` of the rename. Return an error if `new_path` already
/// exists.
RENAME_NOREPLACE;
/// creates a "whiteout" object at the source of the rename at the same time as performing
/// the rename.
///
/// This operation makes sense only for overlay/union filesystem implementations.
RENAME_WHITEOUT;
}
}
feature! {
#![feature = "fs"]
/// Like [`renameat`], but with an additional `flags` argument.
///
/// A `renameat2` call with an empty flags argument is equivalent to `renameat`.
///
/// # See Also
/// * [`rename`](https://man7.org/linux/man-pages/man2/rename.2.html)
#[cfg(all(target_os = "linux", target_env = "gnu"))]
pub fn renameat2<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(
old_dirfd: Option<RawFd>,
old_path: &P1,
new_dirfd: Option<RawFd>,
new_path: &P2,
flags: RenameFlags,
) -> Result<()> {
let res = old_path.with_nix_path(|old_cstr| {
new_path.with_nix_path(|new_cstr| unsafe {
libc::renameat2(
at_rawfd(old_dirfd),
old_cstr.as_ptr(),
at_rawfd(new_dirfd),
new_cstr.as_ptr(),
flags.bits(),
)
})
})??;
Errno::result(res).map(drop)
}
fn wrap_readlink_result(mut v: Vec<u8>, len: ssize_t) -> Result<OsString> {
unsafe { v.set_len(len as usize) }
v.shrink_to_fit();
Ok(OsString::from_vec(v.to_vec()))
}
fn readlink_maybe_at<P: ?Sized + NixPath>(
dirfd: Option<RawFd>,
path: &P,
v: &mut Vec<u8>,
) -> Result<libc::ssize_t> {
path.with_nix_path(|cstr| unsafe {
match dirfd {
#[cfg(target_os = "redox")]
Some(_) => unreachable!(),
#[cfg(not(target_os = "redox"))]
Some(dirfd) => libc::readlinkat(
dirfd,
cstr.as_ptr(),
v.as_mut_ptr().cast(),
v.capacity() as size_t,
),
None => libc::readlink(
cstr.as_ptr(),
v.as_mut_ptr().cast(),
v.capacity() as size_t,
),
}
})
}
fn inner_readlink<P: ?Sized + NixPath>(
dirfd: Option<RawFd>,
path: &P,
) -> Result<OsString> {
#[cfg(not(target_os = "hurd"))]
const PATH_MAX: usize = libc::PATH_MAX as usize;
#[cfg(target_os = "hurd")]
const PATH_MAX: usize = 1024; // Hurd does not define a hard limit, so try a guess first
let mut v = Vec::with_capacity(PATH_MAX);
{
// simple case: result is strictly less than `PATH_MAX`
let res = readlink_maybe_at(dirfd, path, &mut v)?;
let len = Errno::result(res)?;
debug_assert!(len >= 0);
if (len as usize) < v.capacity() {
return wrap_readlink_result(v, res);
}
}
// Uh oh, the result is too long...
// Let's try to ask lstat how many bytes to allocate.
let mut try_size = {
let reported_size = match dirfd {
#[cfg(target_os = "redox")]
Some(_) => unreachable!(),
#[cfg(any(linux_android, target_os = "freebsd", target_os = "hurd"))]
Some(dirfd) => {
let flags = if path.is_empty() {
AtFlags::AT_EMPTY_PATH
} else {
AtFlags::empty()
};
super::sys::stat::fstatat(
Some(dirfd),
path,
flags | AtFlags::AT_SYMLINK_NOFOLLOW,
)
}
#[cfg(not(any(
linux_android,
target_os = "redox",
target_os = "freebsd",
target_os = "hurd"
)))]
Some(dirfd) => super::sys::stat::fstatat(
Some(dirfd),
path,
AtFlags::AT_SYMLINK_NOFOLLOW,
),
None => super::sys::stat::lstat(path),
}
.map(|x| x.st_size)
.unwrap_or(0);
if reported_size > 0 {
// Note: even if `lstat`'s apparently valid answer turns out to be
// wrong, we will still read the full symlink no matter what.
reported_size as usize + 1
} else {
// If lstat doesn't cooperate, or reports an error, be a little less
// precise.
PATH_MAX.max(128) << 1
}
};
loop {
{
v.reserve_exact(try_size);
let res = readlink_maybe_at(dirfd, path, &mut v)?;
let len = Errno::result(res)?;
debug_assert!(len >= 0);
if (len as usize) < v.capacity() {
return wrap_readlink_result(v, res);
}
}
// Ugh! Still not big enough!
match try_size.checked_shl(1) {
Some(next_size) => try_size = next_size,
// It's absurd that this would happen, but handle it sanely
// anyway.
None => break Err(Errno::ENAMETOOLONG),
}
}
}
/// Read value of a symbolic link
///
/// # See Also
/// * [`readlink`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html)
pub fn readlink<P: ?Sized + NixPath>(path: &P) -> Result<OsString> {
inner_readlink(None, path)
}
/// Read value of a symbolic link.
///
/// Equivalent to [`readlink` ] except where `path` specifies a relative path. In that case,
/// interpret `path` relative to open file specified by `dirfd`.
///
/// # See Also
/// * [`readlink`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html)
#[cfg(not(target_os = "redox"))]
pub fn readlinkat<P: ?Sized + NixPath>(
dirfd: Option<RawFd>,
path: &P,
) -> Result<OsString> {
let dirfd = at_rawfd(dirfd);
inner_readlink(Some(dirfd), path)
}
}
#[cfg(any(linux_android, target_os = "freebsd"))]
#[cfg(feature = "fs")]
libc_bitflags!(
/// Additional flags for file sealing, which allows for limiting operations on a file.
#[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
pub struct SealFlag: c_int {
/// Prevents further calls to `fcntl()` with `F_ADD_SEALS`.
F_SEAL_SEAL;
/// The file cannot be reduced in size.
F_SEAL_SHRINK;
/// The size of the file cannot be increased.
F_SEAL_GROW;
/// The file contents cannot be modified.
F_SEAL_WRITE;
/// The file contents cannot be modified, except via shared writable mappings that were
/// created prior to the seal being set. Since Linux 5.1.
#[cfg(linux_android)]
F_SEAL_FUTURE_WRITE;
}
);
#[cfg(feature = "fs")]
libc_bitflags!(
/// Additional configuration flags for `fcntl`'s `F_SETFD`.
#[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
pub struct FdFlag: c_int {
/// The file descriptor will automatically be closed during a successful `execve(2)`.
FD_CLOEXEC;
}
);
feature! {
#![feature = "fs"]
/// Commands for use with [`fcntl`].
#[cfg(not(target_os = "redox"))]
#[derive(Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FcntlArg<'a> {
/// Duplicate the provided file descriptor
F_DUPFD(RawFd),
/// Duplicate the provided file descriptor and set the `FD_CLOEXEC` flag on it.
F_DUPFD_CLOEXEC(RawFd),
/// Get the close-on-exec flag associated with the file descriptor
F_GETFD,
/// Set the close-on-exec flag associated with the file descriptor
F_SETFD(FdFlag), // FD_FLAGS
/// Get descriptor status flags
F_GETFL,
/// Set descriptor status flags
F_SETFL(OFlag), // O_NONBLOCK
/// Set or clear a file segment lock
F_SETLK(&'a libc::flock),
/// Like [`F_SETLK`](FcntlArg::F_SETLK) except that if a shared or exclusive lock is blocked by
/// other locks, the process waits until the request can be satisfied.
F_SETLKW(&'a libc::flock),
/// Get the first lock that blocks the lock description
F_GETLK(&'a mut libc::flock),
/// Acquire or release an open file description lock
#[cfg(linux_android)]
F_OFD_SETLK(&'a libc::flock),
/// Like [`F_OFD_SETLK`](FcntlArg::F_OFD_SETLK) except that if a conflicting lock is held on
/// the file, then wait for that lock to be released.
#[cfg(linux_android)]
F_OFD_SETLKW(&'a libc::flock),
/// Determine whether it would be possible to create the given lock. If not, return details
/// about one existing lock that would prevent it.
#[cfg(linux_android)]
F_OFD_GETLK(&'a mut libc::flock),
/// Add seals to the file
#[cfg(any(
linux_android,
target_os = "freebsd"
))]
F_ADD_SEALS(SealFlag),
/// Get seals associated with the file
#[cfg(any(
linux_android,
target_os = "freebsd"
))]
F_GET_SEALS,
/// Asks the drive to flush all buffered data to permanent storage.
#[cfg(apple_targets)]
F_FULLFSYNC,
/// fsync + issue barrier to drive
#[cfg(apple_targets)]
F_BARRIERFSYNC,
/// Return the capacity of a pipe
#[cfg(linux_android)]
F_GETPIPE_SZ,
/// Change the capacity of a pipe
#[cfg(linux_android)]
F_SETPIPE_SZ(c_int),
/// Look up the path of an open file descriptor, if possible.
#[cfg(any(
target_os = "netbsd",
target_os = "dragonfly",
apple_targets,
))]
F_GETPATH(&'a mut PathBuf),
/// Look up the path of an open file descriptor, if possible.
#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
F_KINFO(&'a mut PathBuf),
/// Return the full path without firmlinks of the fd.
#[cfg(apple_targets)]
F_GETPATH_NOFIRMLINK(&'a mut PathBuf),
// TODO: Rest of flags
}
/// Commands for use with [`fcntl`].
#[cfg(target_os = "redox")]
#[derive(Debug, Clone, Copy, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FcntlArg {
/// Duplicate the provided file descriptor
F_DUPFD(RawFd),
/// Duplicate the provided file descriptor and set the `FD_CLOEXEC` flag on it.
F_DUPFD_CLOEXEC(RawFd),
/// Get the close-on-exec flag associated with the file descriptor
F_GETFD,
/// Set the close-on-exec flag associated with the file descriptor
F_SETFD(FdFlag), // FD_FLAGS
/// Get descriptor status flags
F_GETFL,
/// Set descriptor status flags
F_SETFL(OFlag), // O_NONBLOCK
}
pub use self::FcntlArg::*;
/// Perform various operations on open file descriptors.
///
/// # See Also
/// * [`fcntl`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html)
// TODO: Figure out how to handle value fcntl returns
pub fn fcntl(fd: RawFd, arg: FcntlArg) -> Result<c_int> {
let res = unsafe {
match arg {
F_DUPFD(rawfd) => libc::fcntl(fd, libc::F_DUPFD, rawfd),
F_DUPFD_CLOEXEC(rawfd) => {
libc::fcntl(fd, libc::F_DUPFD_CLOEXEC, rawfd)
}
F_GETFD => libc::fcntl(fd, libc::F_GETFD),
F_SETFD(flag) => libc::fcntl(fd, libc::F_SETFD, flag.bits()),
F_GETFL => libc::fcntl(fd, libc::F_GETFL),
F_SETFL(flag) => libc::fcntl(fd, libc::F_SETFL, flag.bits()),
#[cfg(not(target_os = "redox"))]
F_SETLK(flock) => libc::fcntl(fd, libc::F_SETLK, flock),
#[cfg(not(target_os = "redox"))]
F_SETLKW(flock) => libc::fcntl(fd, libc::F_SETLKW, flock),
#[cfg(not(target_os = "redox"))]
F_GETLK(flock) => libc::fcntl(fd, libc::F_GETLK, flock),
#[cfg(linux_android)]
F_OFD_SETLK(flock) => libc::fcntl(fd, libc::F_OFD_SETLK, flock),
#[cfg(linux_android)]
F_OFD_SETLKW(flock) => libc::fcntl(fd, libc::F_OFD_SETLKW, flock),
#[cfg(linux_android)]
F_OFD_GETLK(flock) => libc::fcntl(fd, libc::F_OFD_GETLK, flock),
#[cfg(any(
linux_android,
target_os = "freebsd"
))]
F_ADD_SEALS(flag) => {
libc::fcntl(fd, libc::F_ADD_SEALS, flag.bits())
}
#[cfg(any(
linux_android,
target_os = "freebsd"
))]
F_GET_SEALS => libc::fcntl(fd, libc::F_GET_SEALS),
#[cfg(apple_targets)]
F_FULLFSYNC => libc::fcntl(fd, libc::F_FULLFSYNC),
#[cfg(apple_targets)]
F_BARRIERFSYNC => libc::fcntl(fd, libc::F_BARRIERFSYNC),
#[cfg(linux_android)]
F_GETPIPE_SZ => libc::fcntl(fd, libc::F_GETPIPE_SZ),
#[cfg(linux_android)]
F_SETPIPE_SZ(size) => libc::fcntl(fd, libc::F_SETPIPE_SZ, size),
#[cfg(any(
target_os = "dragonfly",
target_os = "netbsd",
apple_targets,
))]
F_GETPATH(path) => {
let mut buffer = vec![0; libc::PATH_MAX as usize];
let res = libc::fcntl(fd, libc::F_GETPATH, buffer.as_mut_ptr());
let ok_res = Errno::result(res)?;
let optr = CStr::from_bytes_until_nul(&buffer).unwrap();
*path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
return Ok(ok_res)
},
#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
F_KINFO(path) => {
let mut info: libc::kinfo_file = std::mem::zeroed();
info.kf_structsize = std::mem::size_of::<libc::kinfo_file>() as i32;
let res = libc::fcntl(fd, libc::F_KINFO, &mut info);
let ok_res = Errno::result(res)?;
let p = info.kf_path;
let u8_slice = slice::from_raw_parts(p.as_ptr().cast(), p.len());
let optr = CStr::from_bytes_until_nul(u8_slice).unwrap();
*path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
return Ok(ok_res)
},
#[cfg(apple_targets)]
F_GETPATH_NOFIRMLINK(path) => {
let mut buffer = vec![0; libc::PATH_MAX as usize];
let res = libc::fcntl(fd, libc::F_GETPATH_NOFIRMLINK, buffer.as_mut_ptr());
let ok_res = Errno::result(res)?;
let optr = CStr::from_bytes_until_nul(&buffer).unwrap();
*path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
return Ok(ok_res)
},
}
};
Errno::result(res)
}
/// Operations for use with [`Flock::lock`].
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FlockArg {
/// shared file lock
LockShared,
/// exclusive file lock
LockExclusive,
/// Unlock file
Unlock,
/// Shared lock. Do not block when locking.
LockSharedNonblock,
/// Exclusive lock. Do not block when locking.
LockExclusiveNonblock,
#[allow(missing_docs)]
#[deprecated(since = "0.28.0", note = "Use FlockArg::Unlock instead")]
UnlockNonblock,
}
#[allow(missing_docs)]
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
#[deprecated(since = "0.28.0", note = "`fcntl::Flock` should be used instead.")]
pub fn flock(fd: RawFd, arg: FlockArg) -> Result<()> {
use self::FlockArg::*;
let res = unsafe {
match arg {
LockShared => libc::flock(fd, libc::LOCK_SH),
LockExclusive => libc::flock(fd, libc::LOCK_EX),
Unlock => libc::flock(fd, libc::LOCK_UN),
LockSharedNonblock => {
libc::flock(fd, libc::LOCK_SH | libc::LOCK_NB)
}
LockExclusiveNonblock => {
libc::flock(fd, libc::LOCK_EX | libc::LOCK_NB)
}
#[allow(deprecated)]
UnlockNonblock => libc::flock(fd, libc::LOCK_UN | libc::LOCK_NB),
}
};
Errno::result(res).map(drop)
}
/// Represents valid types for flock.
///
/// # Safety
/// Types implementing this must not be `Clone`.
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
pub unsafe trait Flockable: AsRawFd {}
/// Represents an owned flock, which unlocks on drop.
///
/// See [flock(2)](https://linux.die.net/man/2/flock) for details on locking semantics.
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
#[derive(Debug)]
pub struct Flock<T: Flockable>(T);
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
impl<T: Flockable> Drop for Flock<T> {
fn drop(&mut self) {
let res = Errno::result(unsafe { libc::flock(self.0.as_raw_fd(), libc::LOCK_UN) });
if res.is_err() && !std::thread::panicking() {
panic!("Failed to remove flock: {}", res.unwrap_err());
}
}
}
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
impl<T: Flockable> Deref for Flock<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
&self.0
}
}
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
impl<T: Flockable> DerefMut for Flock<T> {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
impl<T: Flockable> Flock<T> {
/// Obtain a/an flock.
///
/// # Example
/// ```
/// # use std::io::Write;
/// # use std::fs::File;
/// # use nix::fcntl::{Flock, FlockArg};
/// # fn do_stuff(file: File) {
/// let mut file = match Flock::lock(file, FlockArg::LockExclusive) {
/// Ok(l) => l,
/// Err(_) => return,
/// };
///
/// // Do stuff
/// let data = "Foo bar";
/// _ = file.write(data.as_bytes());
/// _ = file.sync_data();
/// # }
pub fn lock(t: T, args: FlockArg) -> std::result::Result<Self, (T, Errno)> {
let flags = match args {
FlockArg::LockShared => libc::LOCK_SH,
FlockArg::LockExclusive => libc::LOCK_EX,
FlockArg::LockSharedNonblock => libc::LOCK_SH | libc::LOCK_NB,
FlockArg::LockExclusiveNonblock => libc::LOCK_EX | libc::LOCK_NB,
#[allow(deprecated)]
FlockArg::Unlock | FlockArg::UnlockNonblock => return Err((t, Errno::EINVAL)),
};
match Errno::result(unsafe { libc::flock(t.as_raw_fd(), flags) }) {
Ok(_) => Ok(Self(t)),
Err(errno) => Err((t, errno)),
}
}
/// Remove the lock and return the object wrapped within.
///
/// # Example
/// ```
/// # use std::fs::File;
/// # use nix::fcntl::{Flock, FlockArg};
/// fn do_stuff(file: File) -> nix::Result<()> {
/// let mut lock = match Flock::lock(file, FlockArg::LockExclusive) {
/// Ok(l) => l,
/// Err((_,e)) => return Err(e),
/// };
///
/// // Do critical section
///
/// // Unlock
/// let file = match lock.unlock() {
/// Ok(f) => f,
/// Err((_, e)) => return Err(e),
/// };
///
/// // Do anything else
///
/// Ok(())
/// }
pub fn unlock(self) -> std::result::Result<T, (Self, Errno)> {
let inner = unsafe { match Errno::result(libc::flock(self.0.as_raw_fd(), libc::LOCK_UN)) {
Ok(_) => std::ptr::read(&self.0),
Err(errno) => return Err((self, errno)),
}};
std::mem::forget(self);
Ok(inner)
}
/// Relock the file. This can upgrade or downgrade the lock type.
///
/// # Example
/// ```
/// # use std::fs::File;
/// # use nix::fcntl::{Flock, FlockArg};
/// # use tempfile::tempfile;
/// let f: std::fs::File = tempfile().unwrap();
/// let locked_file = Flock::lock(f, FlockArg::LockExclusive).unwrap();
/// // Do stuff, then downgrade the lock
/// locked_file.relock(FlockArg::LockShared).unwrap();
/// ```
pub fn relock(&self, arg: FlockArg) -> Result<()> {
let flags = match arg {
FlockArg::LockShared => libc::LOCK_SH,
FlockArg::LockExclusive => libc::LOCK_EX,
FlockArg::LockSharedNonblock => libc::LOCK_SH | libc::LOCK_NB,
FlockArg::LockExclusiveNonblock => libc::LOCK_EX | libc::LOCK_NB,
#[allow(deprecated)]
FlockArg::Unlock | FlockArg::UnlockNonblock => return Err(Errno::EINVAL),
};
Errno::result(unsafe { libc::flock(self.as_raw_fd(), flags) }).map(drop)
}
}
// Safety: `File` is not [std::clone::Clone].
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
unsafe impl Flockable for std::fs::File {}
// Safety: `OwnedFd` is not [std::clone::Clone].
#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
unsafe impl Flockable for OwnedFd {}
}
#[cfg(linux_android)]
#[cfg(feature = "zerocopy")]
libc_bitflags! {
/// Additional flags to `splice` and friends.
#[cfg_attr(docsrs, doc(cfg(feature = "zerocopy")))]
pub struct SpliceFFlags: c_uint {
/// Request that pages be moved instead of copied.
///
/// Not applicable to `vmsplice`.
SPLICE_F_MOVE;
/// Do not block on I/O.
SPLICE_F_NONBLOCK;
/// Hint that more data will be coming in a subsequent splice.
///
/// Not applicable to `vmsplice`.
SPLICE_F_MORE;
/// Gift the user pages to the kernel.
///
/// Not applicable to `splice`.
SPLICE_F_GIFT;
}
}
feature! {
#![feature = "zerocopy"]
/// Copy a range of data from one file to another
///
/// The `copy_file_range` system call performs an in-kernel copy between
/// file descriptors `fd_in` and `fd_out` without the additional cost of
/// transferring data from the kernel to user space and back again. There may be
/// additional optimizations for specific file systems. It copies up to `len`
/// bytes of data from file descriptor `fd_in` to file descriptor `fd_out`,
/// overwriting any data that exists within the requested range of the target
/// file.
///
/// If the `off_in` and/or `off_out` arguments are used, the values
/// will be mutated to reflect the new position within the file after
/// copying. If they are not used, the relevant file descriptors will be seeked
/// to the new position.
///
/// On successful completion the number of bytes actually copied will be
/// returned.
// Note: FreeBSD defines the offset argument as "off_t". Linux and Android
// define it as "loff_t". But on both OSes, on all supported platforms, those
// are 64 bits. So Nix uses i64 to make the docs simple and consistent.
#[cfg(any(linux_android, target_os = "freebsd"))]
pub fn copy_file_range<Fd1: AsFd, Fd2: AsFd>(
fd_in: Fd1,
off_in: Option<&mut i64>,
fd_out: Fd2,
off_out: Option<&mut i64>,
len: usize,
) -> Result<usize> {
let off_in = off_in
.map(|offset| offset as *mut i64)
.unwrap_or(ptr::null_mut());
let off_out = off_out
.map(|offset| offset as *mut i64)
.unwrap_or(ptr::null_mut());
cfg_if::cfg_if! {
if #[cfg(target_os = "freebsd")] {
let ret = unsafe {
libc::copy_file_range(
fd_in.as_fd().as_raw_fd(),
off_in,
fd_out.as_fd().as_raw_fd(),
off_out,
len,
0,
)
};
} else {
// May Linux distros still don't include copy_file_range in their
// libc implementations, so we need to make a direct syscall.
let ret = unsafe {
libc::syscall(
libc::SYS_copy_file_range,
fd_in.as_fd().as_raw_fd(),
off_in,
fd_out.as_fd().as_raw_fd(),
off_out,
len,
0,
)
};
}
}
Errno::result(ret).map(|r| r as usize)
}
/// Splice data to/from a pipe
///
/// # See Also
/// *[`splice`](https://man7.org/linux/man-pages/man2/splice.2.html)
#[cfg(linux_android)]
pub fn splice<Fd1: AsFd, Fd2: AsFd>(
fd_in: Fd1,
off_in: Option<&mut libc::loff_t>,
fd_out: Fd2,
off_out: Option<&mut libc::loff_t>,
len: usize,
flags: SpliceFFlags,
) -> Result<usize> {
let off_in = off_in
.map(|offset| offset as *mut libc::loff_t)
.unwrap_or(ptr::null_mut());
let off_out = off_out
.map(|offset| offset as *mut libc::loff_t)
.unwrap_or(ptr::null_mut());
let ret = unsafe {
libc::splice(fd_in.as_fd().as_raw_fd(), off_in, fd_out.as_fd().as_raw_fd(), off_out, len, flags.bits())
};
Errno::result(ret).map(|r| r as usize)
}
/// Duplicate pipe content
///
/// # See Also
/// *[`tee`](https://man7.org/linux/man-pages/man2/tee.2.html)
#[cfg(linux_android)]
pub fn tee<Fd1: AsFd, Fd2: AsFd>(
fd_in: Fd1,
fd_out: Fd2,
len: usize,
flags: SpliceFFlags,
) -> Result<usize> {
let ret = unsafe { libc::tee(fd_in.as_fd().as_raw_fd(), fd_out.as_fd().as_raw_fd(), len, flags.bits()) };
Errno::result(ret).map(|r| r as usize)
}
/// Splice user pages to/from a pipe
///
/// # See Also
/// *[`vmsplice`](https://man7.org/linux/man-pages/man2/vmsplice.2.html)
#[cfg(linux_android)]
pub fn vmsplice<F: AsFd>(
fd: F,
iov: &[std::io::IoSlice<'_>],
flags: SpliceFFlags,
) -> Result<usize> {
let ret = unsafe {
libc::vmsplice(
fd.as_fd().as_raw_fd(),
iov.as_ptr().cast(),
iov.len(),
flags.bits(),
)
};
Errno::result(ret).map(|r| r as usize)
}
}
#[cfg(target_os = "linux")]
#[cfg(feature = "fs")]
libc_bitflags!(
/// Mode argument flags for fallocate determining operation performed on a given range.
#[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
pub struct FallocateFlags: c_int {
/// File size is not changed.
///
/// offset + len can be greater than file size.
FALLOC_FL_KEEP_SIZE;
/// Deallocates space by creating a hole.
///
/// Must be ORed with FALLOC_FL_KEEP_SIZE. Byte range starts at offset and continues for len bytes.
FALLOC_FL_PUNCH_HOLE;
/// Removes byte range from a file without leaving a hole.
///
/// Byte range to collapse starts at offset and continues for len bytes.
FALLOC_FL_COLLAPSE_RANGE;
/// Zeroes space in specified byte range.
///
/// Byte range starts at offset and continues for len bytes.
FALLOC_FL_ZERO_RANGE;
/// Increases file space by inserting a hole within the file size.
///
/// Does not overwrite existing data. Hole starts at offset and continues for len bytes.
FALLOC_FL_INSERT_RANGE;
/// Shared file data extants are made private to the file.
///
/// Gaurantees that a subsequent write will not fail due to lack of space.
FALLOC_FL_UNSHARE_RANGE;
}
);
feature! {
#![feature = "fs"]
/// Manipulates file space.
///
/// Allows the caller to directly manipulate the allocated disk space for the
/// file referred to by fd.
#[cfg(target_os = "linux")]
#[cfg(feature = "fs")]
pub fn fallocate(
fd: RawFd,
mode: FallocateFlags,
offset: libc::off_t,
len: libc::off_t,
) -> Result<()> {
let res = unsafe { libc::fallocate(fd, mode.bits(), offset, len) };
Errno::result(res).map(drop)
}
/// Argument to [`fspacectl`] describing the range to zero. The first member is
/// the file offset, and the second is the length of the region.
#[cfg(any(target_os = "freebsd"))]
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct SpacectlRange(pub libc::off_t, pub libc::off_t);
#[cfg(any(target_os = "freebsd"))]
impl SpacectlRange {
/// Is the range empty?
///
/// After a successful call to [`fspacectl`], A value of `true` for `SpacectlRange::is_empty`
/// indicates that the operation is complete.
#[inline]
pub fn is_empty(&self) -> bool {
self.1 == 0
}
/// Remaining length of the range
#[inline]
pub fn len(&self) -> libc::off_t {
self.1
}
/// Next file offset to operate on
#[inline]
pub fn offset(&self) -> libc::off_t {
self.0
}
}
/// Punch holes in a file.
///
/// `fspacectl` instructs the file system to deallocate a portion of a file.
/// After a successful operation, this region of the file will return all zeroes
/// if read. If the file system supports deallocation, then it may free the
/// underlying storage, too.
///
/// # Arguments
///
/// - `fd` - File to operate on
/// - `range.0` - File offset at which to begin deallocation
/// - `range.1` - Length of the region to deallocate
///
/// # Returns
///
/// The operation may deallocate less than the entire requested region. On
/// success, it returns the region that still remains to be deallocated. The
/// caller should loop until the returned region is empty.
///
/// # Example
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use std::io::Write;
/// # use std::os::unix::fs::FileExt;
/// # use std::os::unix::io::AsRawFd;
/// # use nix::fcntl::*;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"0123456789abcdef";
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// let mut range = SpacectlRange(3, 6);
/// while (!range.is_empty()) {
/// range = fspacectl(f.as_raw_fd(), range).unwrap();
/// }
/// let mut buf = vec![0; INITIAL.len()];
/// f.read_exact_at(&mut buf, 0).unwrap();
/// assert_eq!(buf, b"012\0\0\0\0\0\09abcdef");
/// ```
#[cfg(target_os = "freebsd")]
#[inline] // Delays codegen, preventing linker errors with dylibs and --no-allow-shlib-undefined
pub fn fspacectl(fd: RawFd, range: SpacectlRange) -> Result<SpacectlRange> {
let mut rqsr = libc::spacectl_range {
r_offset: range.0,
r_len: range.1,
};
let res = unsafe {
libc::fspacectl(
fd,
libc::SPACECTL_DEALLOC, // Only one command is supported ATM
&rqsr,
0, // No flags are currently supported
&mut rqsr,
)
};
Errno::result(res).map(|_| SpacectlRange(rqsr.r_offset, rqsr.r_len))
}
/// Like [`fspacectl`], but will never return incomplete.
///
/// # Arguments
///
/// - `fd` - File to operate on
/// - `offset` - File offset at which to begin deallocation
/// - `len` - Length of the region to deallocate
///
/// # Returns
///
/// Returns `()` on success. On failure, the region may or may not be partially
/// deallocated.
///
/// # Example
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use std::io::Write;
/// # use std::os::unix::fs::FileExt;
/// # use std::os::unix::io::AsRawFd;
/// # use nix::fcntl::*;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"0123456789abcdef";
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// fspacectl_all(f.as_raw_fd(), 3, 6).unwrap();
/// let mut buf = vec![0; INITIAL.len()];
/// f.read_exact_at(&mut buf, 0).unwrap();
/// assert_eq!(buf, b"012\0\0\0\0\0\09abcdef");
/// ```
#[cfg(target_os = "freebsd")]
#[inline] // Delays codegen, preventing linker errors with dylibs and --no-allow-shlib-undefined
pub fn fspacectl_all(
fd: RawFd,
offset: libc::off_t,
len: libc::off_t,
) -> Result<()> {
let mut rqsr = libc::spacectl_range {
r_offset: offset,
r_len: len,
};
while rqsr.r_len > 0 {
let res = unsafe {
libc::fspacectl(
fd,
libc::SPACECTL_DEALLOC, // Only one command is supported ATM
&rqsr,
0, // No flags are currently supported
&mut rqsr,
)
};
Errno::result(res)?;
}
Ok(())
}
#[cfg(any(
linux_android,
target_os = "emscripten",
target_os = "fuchsia",
target_os = "wasi",
target_env = "uclibc",
target_os = "freebsd"
))]
mod posix_fadvise {
use crate::errno::Errno;
use crate::Result;
use std::os::unix::io::RawFd;
#[cfg(feature = "fs")]
libc_enum! {
/// The specific advice provided to [`posix_fadvise`].
#[repr(i32)]
#[non_exhaustive]
#[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
pub enum PosixFadviseAdvice {
/// Revert to the default data access behavior.
POSIX_FADV_NORMAL,
/// The file data will be accessed sequentially.
POSIX_FADV_SEQUENTIAL,
/// A hint that file data will be accessed randomly, and prefetching is likely not
/// advantageous.
POSIX_FADV_RANDOM,
/// The specified data will only be accessed once and then not reused.
POSIX_FADV_NOREUSE,
/// The specified data will be accessed in the near future.
POSIX_FADV_WILLNEED,
/// The specified data will not be accessed in the near future.
POSIX_FADV_DONTNEED,
}
}
feature! {
#![feature = "fs"]
/// Allows a process to describe to the system its data access behavior for an open file
/// descriptor.
///
/// # See Also
/// * [`posix_fadvise`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fadvise.html)
pub fn posix_fadvise(
fd: RawFd,
offset: libc::off_t,
len: libc::off_t,
advice: PosixFadviseAdvice,
) -> Result<()> {
let res = unsafe { libc::posix_fadvise(fd, offset, len, advice as libc::c_int) };
if res == 0 {
Ok(())
} else {
Err(Errno::from_raw(res))
}
}
}
}
/// Pre-allocate storage for a range in a file
///
/// # See Also
/// * [`posix_fallocate`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html)
#[cfg(any(
linux_android,
freebsdlike,
target_os = "emscripten",
target_os = "fuchsia",
target_os = "wasi",
))]
pub fn posix_fallocate(
fd: RawFd,
offset: libc::off_t,
len: libc::off_t,
) -> Result<()> {
let res = unsafe { libc::posix_fallocate(fd, offset, len) };
match Errno::result(res) {
Err(err) => Err(err),
Ok(0) => Ok(()),
Ok(errno) => Err(Errno::from_raw(errno)),
}
}
}