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-rw-r--r--vendor/rustix/src/fs/at.rs88
1 files changed, 49 insertions, 39 deletions
diff --git a/vendor/rustix/src/fs/at.rs b/vendor/rustix/src/fs/at.rs
index 2314cf763..0c99cc30a 100644
--- a/vendor/rustix/src/fs/at.rs
+++ b/vendor/rustix/src/fs/at.rs
@@ -1,9 +1,9 @@
//! POSIX-style `*at` functions.
//!
//! The `dirfd` argument to these functions may be a file descriptor for a
-//! directory, or the special value returned by [`cwd`].
+//! directory, or the special value [`CWD`].
//!
-//! [`cwd`]: crate::fs::cwd
+//! [`cwd`]: crate::fs::cwd::CWD
use crate::fd::OwnedFd;
use crate::ffi::{CStr, CString};
@@ -11,16 +11,16 @@ use crate::ffi::{CStr, CString};
use crate::fs::CloneFlags;
#[cfg(not(any(apple, target_os = "wasi")))]
use crate::fs::FileType;
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(linux_kernel)]
use crate::fs::RenameFlags;
use crate::fs::{Access, AtFlags, Mode, OFlags, Stat, Timestamps};
-use crate::path::SMALL_PATH_BUFFER_SIZE;
#[cfg(not(target_os = "wasi"))]
-use crate::process::{Gid, Uid};
+use crate::fs::{Gid, Uid};
+use crate::path::SMALL_PATH_BUFFER_SIZE;
+use crate::timespec::Nsecs;
use crate::{backend, io, path};
use alloc::vec::Vec;
use backend::fd::{AsFd, BorrowedFd};
-use backend::time::types::Nsecs;
pub use backend::fs::types::{Dev, RawMode};
@@ -49,7 +49,7 @@ pub const UTIME_OMIT: Nsecs = backend::c::UTIME_OMIT as Nsecs;
/// - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/openat.html
-/// [Linux]: https://man7.org/linux/man-pages/man2/open.2.html
+/// [Linux]: https://man7.org/linux/man-pages/man2/openat.2.html
#[inline]
pub fn openat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
@@ -64,7 +64,7 @@ pub fn openat<P: path::Arg, Fd: AsFd>(
/// `readlinkat(fd, path)`—Reads the contents of a symlink.
///
-/// If `reuse` is non-empty, reuse its buffer to store the result if possible.
+/// If `reuse` already has available capacity, reuse it if possible.
///
/// # References
/// - [POSIX]
@@ -81,24 +81,44 @@ pub fn readlinkat<P: path::Arg, Fd: AsFd, B: Into<Vec<u8>>>(
path.into_with_c_str(|path| _readlinkat(dirfd.as_fd(), path, reuse.into()))
}
+#[allow(unsafe_code)]
fn _readlinkat(dirfd: BorrowedFd<'_>, path: &CStr, mut buffer: Vec<u8>) -> io::Result<CString> {
- // This code would benefit from having a better way to read into
- // uninitialized memory, but that requires `unsafe`.
buffer.clear();
buffer.reserve(SMALL_PATH_BUFFER_SIZE);
- buffer.resize(buffer.capacity(), 0_u8);
loop {
- let nread = backend::fs::syscalls::readlinkat(dirfd.as_fd(), path, &mut buffer)?;
+ 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 man page:
+ // "On success, these calls return the number of bytes placed in buf."
+ unsafe {
+ buffer.set_len(nread);
+ }
- let nread = nread as usize;
- assert!(nread <= buffer.len());
- if nread < buffer.len() {
- buffer.resize(nread, 0_u8);
- return Ok(CString::new(buffer).unwrap());
+ // 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/9699919799/basedefs/V1_chap03.html#tag_03_271
+ // [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_375
+ unsafe {
+ return Ok(CString::from_vec_unchecked(buffer));
+ }
}
- buffer.reserve(1); // use `Vec` reallocation strategy to grow capacity exponentially
- buffer.resize(buffer.capacity(), 0_u8);
+
+ buffer.reserve(buffer.capacity() + 1); // use `Vec` reallocation
+ // strategy to grow capacity
+ // exponentially
}
}
@@ -197,7 +217,7 @@ pub fn renameat<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
/// - [Linux]
///
/// [Linux]: https://man7.org/linux/man-pages/man2/renameat2.2.html
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(linux_kernel)]
#[inline]
#[doc(alias = "renameat2")]
pub fn renameat_with<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
@@ -263,6 +283,13 @@ pub fn statat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, flags: AtFlags) -> io:
/// `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]
@@ -298,23 +325,6 @@ pub fn utimensat<P: path::Arg, Fd: AsFd>(
path.into_with_c_str(|path| backend::fs::syscalls::utimensat(dirfd.as_fd(), path, times, flags))
}
-/// `fchmodat(dirfd, path, mode, 0)`—Sets file or directory permissions.
-///
-/// See `fchmodat_with` for a version that does take flags.
-///
-/// # References
-/// - [POSIX]
-/// - [Linux]
-///
-/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmodat.html
-/// [Linux]: https://man7.org/linux/man-pages/man2/fchmodat.2.html
-#[cfg(not(target_os = "wasi"))]
-#[inline]
-#[doc(alias = "fchmodat")]
-pub fn chmodat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, mode: Mode) -> io::Result<()> {
- chmodat_with(dirfd, path, mode, AtFlags::empty())
-}
-
/// `fchmodat(dirfd, path, mode, flags)`—Sets file or directory permissions.
///
/// Platform support for flags varies widely, for example on Linux
@@ -329,8 +339,8 @@ pub fn chmodat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, mode: Mode) -> io::Re
/// [Linux]: https://man7.org/linux/man-pages/man2/fchmodat.2.html
#[cfg(not(target_os = "wasi"))]
#[inline]
-#[doc(alias = "fchmodat_with")]
-pub fn chmodat_with<P: path::Arg, Fd: AsFd>(
+#[doc(alias = "fchmodat")]
+pub fn chmodat<P: path::Arg, Fd: AsFd>(
dirfd: Fd,
path: P,
mode: Mode,
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-24 13:03:48 +0000