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
//! POSIX-style `*at` functions.
//!
//! The `dirfd` argument to these functions may be a file descriptor for a
//! directory, the special value [`CWD`], or the special value [`ABS`].
//!
//! [`CWD`]: crate::fs::CWD
//! [`ABS`]: crate::fs::ABS
use crate::fd::OwnedFd;
use crate::ffi::CStr;
#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
use crate::fs::Access;
#[cfg(not(target_os = "espidf"))]
use crate::fs::AtFlags;
#[cfg(apple)]
use crate::fs::CloneFlags;
#[cfg(linux_kernel)]
use crate::fs::RenameFlags;
#[cfg(not(target_os = "espidf"))]
use crate::fs::Stat;
#[cfg(not(any(apple, target_os = "espidf", target_os = "vita", target_os = "wasi")))]
use crate::fs::{Dev, FileType};
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
use crate::fs::{Gid, Uid};
use crate::fs::{Mode, OFlags};
use crate::{backend, io, path};
use backend::fd::{AsFd, BorrowedFd};
use core::mem::MaybeUninit;
use core::slice;
#[cfg(feature = "alloc")]
use {crate::ffi::CString, crate::path::SMALL_PATH_BUFFER_SIZE, alloc::vec::Vec};
#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
use {crate::fs::Timestamps, crate::timespec::Nsecs};
/// `UTIME_NOW` for use with [`utimensat`].
///
/// [`utimensat`]: crate::fs::utimensat
#[cfg(not(any(target_os = "espidf", target_os = "redox", target_os = "vita")))]
pub const UTIME_NOW: Nsecs = backend::c::UTIME_NOW as Nsecs;
/// `UTIME_OMIT` for use with [`utimensat`].
///
/// [`utimensat`]: crate::fs::utimensat
#[cfg(not(any(target_os = "espidf", target_os = "redox", target_os = "vita")))]
pub const UTIME_OMIT: Nsecs = backend::c::UTIME_OMIT as Nsecs;
/// `openat(dirfd, path, oflags, mode)`—Opens a file.
///
/// POSIX guarantees that `openat` will use the lowest unused file descriptor,
/// however it is not safe in general to rely on this, as file descriptors may
/// be unexpectedly allocated on other threads or in libraries.
///
/// The `Mode` argument is only significant when creating a file.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/openat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/openat.2.html
#[inline]
pub fn openat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
oflags: OFlags,
create_mode: Mode,
) -> io::Result<OwnedFd> {
path.into_with_c_str(|path| {
backend::fs::syscalls::openat(dirfd.as_fd(), path, oflags, create_mode)
})
}
/// `readlinkat(fd, path)`—Reads the contents of a symlink.
///
/// If `reuse` already has available capacity, reuse it if possible.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/readlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/readlinkat.2.html
#[cfg(feature = "alloc")]
#[inline]
pub fn readlinkat<P: path::Arg, Fd: AsFd, B: Into<Vec<u8>>>(
dirfd: Fd,
path: P,
reuse: B,
) -> io::Result<CString> {
path.into_with_c_str(|path| _readlinkat(dirfd.as_fd(), path, reuse.into()))
}
#[cfg(feature = "alloc")]
#[allow(unsafe_code)]
fn _readlinkat(dirfd: BorrowedFd<'_>, path: &CStr, mut buffer: Vec<u8>) -> io::Result<CString> {
buffer.clear();
buffer.reserve(SMALL_PATH_BUFFER_SIZE);
loop {
let nread =
backend::fs::syscalls::readlinkat(dirfd.as_fd(), path, buffer.spare_capacity_mut())?;
debug_assert!(nread <= buffer.capacity());
if nread < buffer.capacity() {
// SAFETY: From the [documentation]: “On success, these calls
// return the number of bytes placed in buf.”
//
// [documentation]: https://man7.org/linux/man-pages/man2/readlinkat.2.html
unsafe {
buffer.set_len(nread);
}
// SAFETY:
// - “readlink places the contents of the symbolic link pathname
// in the buffer buf”
// - [POSIX definition 3.271: Pathname]: “A string that is used
// to identify a file.”
// - [POSIX definition 3.375: String]: “A contiguous sequence of
// bytes terminated by and including the first null byte.”
// - “readlink does not append a terminating null byte to buf.”
//
// Thus, there will be no NUL bytes in the string.
//
// [POSIX definition 3.271: Pathname]: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap03.html#tag_03_271
// [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap03.html#tag_03_375
unsafe {
return Ok(CString::from_vec_unchecked(buffer));
}
}
// Use `Vec` reallocation strategy to grow capacity exponentially.
buffer.reserve(buffer.capacity() + 1);
}
}
/// `readlinkat(fd, path)`—Reads the contents of a symlink, without
/// allocating.
///
/// This is the "raw" version which avoids allocating, but which is
/// significantly trickier to use; most users should use plain [`readlinkat`].
///
/// This version writes bytes into the buffer and returns two slices, one
/// containing the written bytes, and one containing the remaining
/// uninitialized space. If the number of written bytes is equal to the length
/// of the buffer, it means the buffer wasn't big enough to hold the full
/// string, and callers should try again with a bigger buffer.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/readlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/readlinkat.2.html
#[inline]
pub fn readlinkat_raw<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
buf: &mut [MaybeUninit<u8>],
) -> io::Result<(&mut [u8], &mut [MaybeUninit<u8>])> {
path.into_with_c_str(|path| _readlinkat_raw(dirfd.as_fd(), path, buf))
}
#[allow(unsafe_code)]
fn _readlinkat_raw<'a>(
dirfd: BorrowedFd<'_>,
path: &CStr,
buf: &'a mut [MaybeUninit<u8>],
) -> io::Result<(&'a mut [u8], &'a mut [MaybeUninit<u8>])> {
let n = backend::fs::syscalls::readlinkat(dirfd.as_fd(), path, buf)?;
unsafe {
Ok((
slice::from_raw_parts_mut(buf.as_mut_ptr().cast::<u8>(), n),
&mut buf[n..],
))
}
}
/// `mkdirat(fd, path, mode)`—Creates a directory.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/mkdirat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/mkdirat.2.html
#[inline]
pub fn mkdirat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, mode: Mode) -> io::Result<()> {
path.into_with_c_str(|path| backend::fs::syscalls::mkdirat(dirfd.as_fd(), path, mode))
}
/// `linkat(old_dirfd, old_path, new_dirfd, new_path, flags)`—Creates a hard
/// link.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/linkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/linkat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
pub fn linkat<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
old_dirfd: PFd,
old_path: P,
new_dirfd: QFd,
new_path: Q,
flags: AtFlags,
) -> io::Result<()> {
old_path.into_with_c_str(|old_path| {
new_path.into_with_c_str(|new_path| {
backend::fs::syscalls::linkat(
old_dirfd.as_fd(),
old_path,
new_dirfd.as_fd(),
new_path,
flags,
)
})
})
}
/// `unlinkat(fd, path, flags)`—Unlinks a file or remove a directory.
///
/// With the [`REMOVEDIR`] flag, this removes a directory. This is in place of
/// a `rmdirat` function.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [`REMOVEDIR`]: AtFlags::REMOVEDIR
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/unlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/unlinkat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
pub fn unlinkat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, flags: AtFlags) -> io::Result<()> {
path.into_with_c_str(|path| backend::fs::syscalls::unlinkat(dirfd.as_fd(), path, flags))
}
/// `renameat(old_dirfd, old_path, new_dirfd, new_path)`—Renames a file or
/// directory.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/renameat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/renameat.2.html
#[inline]
pub fn renameat<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
old_dirfd: PFd,
old_path: P,
new_dirfd: QFd,
new_path: Q,
) -> io::Result<()> {
old_path.into_with_c_str(|old_path| {
new_path.into_with_c_str(|new_path| {
backend::fs::syscalls::renameat(
old_dirfd.as_fd(),
old_path,
new_dirfd.as_fd(),
new_path,
)
})
})
}
/// `renameat2(old_dirfd, old_path, new_dirfd, new_path, flags)`—Renames a
/// file or directory.
///
/// # References
/// - [Linux]
///
/// [Linux]: https://man7.org/linux/man-pages/man2/renameat2.2.html
#[cfg(linux_kernel)]
#[inline]
#[doc(alias = "renameat2")]
pub fn renameat_with<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
old_dirfd: PFd,
old_path: P,
new_dirfd: QFd,
new_path: Q,
flags: RenameFlags,
) -> io::Result<()> {
old_path.into_with_c_str(|old_path| {
new_path.into_with_c_str(|new_path| {
backend::fs::syscalls::renameat2(
old_dirfd.as_fd(),
old_path,
new_dirfd.as_fd(),
new_path,
flags,
)
})
})
}
/// `symlinkat(old_path, new_dirfd, new_path)`—Creates a symlink.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/symlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/symlinkat.2.html
#[inline]
pub fn symlinkat<P: path::Arg, Q: path::Arg, Fd: AsFd>(
old_path: P,
new_dirfd: Fd,
new_path: Q,
) -> io::Result<()> {
old_path.into_with_c_str(|old_path| {
new_path.into_with_c_str(|new_path| {
backend::fs::syscalls::symlinkat(old_path, new_dirfd.as_fd(), new_path)
})
})
}
/// `fstatat(dirfd, path, flags)`—Queries metadata for a file or directory.
///
/// [`Mode::from_raw_mode`] and [`FileType::from_raw_mode`] may be used to
/// interpret the `st_mode` field.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fstatat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fstatat.2.html
/// [`Mode::from_raw_mode`]: crate::fs::Mode::from_raw_mode
/// [`FileType::from_raw_mode`]: crate::fs::FileType::from_raw_mode
#[cfg(not(target_os = "espidf"))]
#[inline]
#[doc(alias = "fstatat")]
pub fn statat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, flags: AtFlags) -> io::Result<Stat> {
path.into_with_c_str(|path| backend::fs::syscalls::statat(dirfd.as_fd(), path, flags))
}
/// `faccessat(dirfd, path, access, flags)`—Tests permissions for a file or
/// directory.
///
/// On Linux before 5.8, this function uses the `faccessat` system call which
/// doesn't support any flags. This function emulates support for the
/// [`AtFlags::EACCESS`] flag by checking whether the uid and gid of the
/// process match the effective uid and gid, in which case the `EACCESS` flag
/// can be ignored. In Linux 5.8 and beyond `faccessat2` is used, which
/// supports flags.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/faccessat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/faccessat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
#[inline]
#[doc(alias = "faccessat")]
pub fn accessat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
access: Access,
flags: AtFlags,
) -> io::Result<()> {
path.into_with_c_str(|path| backend::fs::syscalls::accessat(dirfd.as_fd(), path, access, flags))
}
/// `utimensat(dirfd, path, times, flags)`—Sets file or directory timestamps.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/utimensat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/utimensat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
#[inline]
pub fn utimensat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
times: &Timestamps,
flags: AtFlags,
) -> io::Result<()> {
path.into_with_c_str(|path| backend::fs::syscalls::utimensat(dirfd.as_fd(), path, times, flags))
}
/// `fchmodat(dirfd, path, mode, flags)`—Sets file or directory permissions.
///
/// Platform support for flags varies widely, for example on Linux
/// [`AtFlags::SYMLINK_NOFOLLOW`] is not implemented and therefore
/// [`io::Errno::OPNOTSUPP`] will be returned.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fchmodat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fchmodat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
#[inline]
#[doc(alias = "fchmodat")]
pub fn chmodat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
mode: Mode,
flags: AtFlags,
) -> io::Result<()> {
path.into_with_c_str(|path| backend::fs::syscalls::chmodat(dirfd.as_fd(), path, mode, flags))
}
/// `fclonefileat(src, dst_dir, dst, flags)`—Efficiently copies between files.
///
/// # References
/// - [Apple]
///
/// [Apple]: https://opensource.apple.com/source/xnu/xnu-3789.21.4/bsd/man/man2/clonefile.2.auto.html
#[cfg(apple)]
#[inline]
pub fn fclonefileat<Fd: AsFd, DstFd: AsFd, P: path::Arg>(
src: Fd,
dst_dir: DstFd,
dst: P,
flags: CloneFlags,
) -> io::Result<()> {
dst.into_with_c_str(|dst| {
backend::fs::syscalls::fclonefileat(src.as_fd(), dst_dir.as_fd(), dst, flags)
})
}
/// `mknodat(dirfd, path, mode, dev)`—Creates special or normal files.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/mknodat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/mknodat.2.html
#[cfg(not(any(apple, target_os = "espidf", target_os = "vita", target_os = "wasi")))]
#[inline]
pub fn mknodat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
file_type: FileType,
mode: Mode,
dev: Dev,
) -> io::Result<()> {
path.into_with_c_str(|path| {
backend::fs::syscalls::mknodat(dirfd.as_fd(), path, file_type, mode, dev)
})
}
/// `fchownat(dirfd, path, owner, group, flags)`—Sets file or directory
/// ownership.
///
/// # References
/// - [POSIX]
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fchownat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fchownat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
#[inline]
#[doc(alias = "fchownat")]
pub fn chownat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
owner: Option<Uid>,
group: Option<Gid>,
flags: AtFlags,
) -> io::Result<()> {
path.into_with_c_str(|path| {
backend::fs::syscalls::chownat(dirfd.as_fd(), path, owner, group, flags)
})
}