Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 2514 insertions, 0 deletions

diff --git a/vendor/rustix/src/backend/libc/fs/syscalls.rs b/vendor/rustix/src/backend/libc/fs/syscalls.rs
new file mode 100644
index 0000000..70e86cf
--- /dev/null
+++ b/vendor/rustix/src/backend/libc/fs/syscalls.rs
@@ -0,0 +1,2514 @@
+//! libc syscalls supporting `rustix::fs`.
+
+use crate::backend::c;
+#[cfg(any(
+    not(target_os = "redox"),
+    feature = "alloc",
+    all(linux_kernel, feature = "procfs")
+))]
+use crate::backend::conv::ret_usize;
+use crate::backend::conv::{borrowed_fd, c_str, ret, ret_c_int, ret_off_t, ret_owned_fd};
+use crate::fd::{BorrowedFd, OwnedFd};
+use crate::ffi::CStr;
+#[cfg(all(apple, feature = "alloc"))]
+use crate::ffi::CString;
+#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
+use crate::fs::Access;
+#[cfg(not(any(
+    apple,
+    netbsdlike,
+    solarish,
+    target_os = "dragonfly",
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "redox",
+    target_os = "vita",
+)))]
+use crate::fs::Advice;
+#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
+use crate::fs::AtFlags;
+#[cfg(not(any(
+    netbsdlike,
+    solarish,
+    target_os = "aix",
+    target_os = "dragonfly",
+    target_os = "espidf",
+    target_os = "nto",
+    target_os = "redox",
+    target_os = "vita",
+)))]
+use crate::fs::FallocateFlags;
+#[cfg(not(any(target_os = "espidf", target_os = "vita", target_os = "wasi")))]
+use crate::fs::FlockOperation;
+#[cfg(any(linux_kernel, target_os = "freebsd"))]
+use crate::fs::MemfdFlags;
+#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
+use crate::fs::SealFlags;
+#[cfg(not(any(
+    solarish,
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "netbsd",
+    target_os = "nto",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi",
+)))]
+use crate::fs::StatFs;
+#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
+use crate::fs::Timestamps;
+#[cfg(not(any(
+    apple,
+    target_os = "espidf",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi"
+)))]
+use crate::fs::{Dev, FileType};
+use crate::fs::{Mode, OFlags, SeekFrom, Stat};
+#[cfg(not(any(target_os = "haiku", target_os = "redox", target_os = "wasi")))]
+use crate::fs::{StatVfs, StatVfsMountFlags};
+use crate::io;
+#[cfg(all(target_env = "gnu", fix_y2038))]
+use crate::timespec::LibcTimespec;
+#[cfg(not(target_os = "wasi"))]
+use crate::ugid::{Gid, Uid};
+#[cfg(all(apple, feature = "alloc"))]
+use alloc::vec;
+use core::mem::MaybeUninit;
+#[cfg(apple)]
+use {
+    crate::backend::conv::nonnegative_ret,
+    crate::fs::{copyfile_state_t, CloneFlags, CopyfileFlags},
+};
+#[cfg(any(apple, linux_kernel))]
+use {crate::fs::XattrFlags, core::mem::size_of, core::ptr::null_mut};
+#[cfg(linux_kernel)]
+use {
+    crate::fs::{RenameFlags, ResolveFlags, Statx, StatxFlags, CWD},
+    core::ptr::null,
+};
+
+#[cfg(all(target_env = "gnu", fix_y2038))]
+weak!(fn __utimensat64(c::c_int, *const c::c_char, *const LibcTimespec, c::c_int) -> c::c_int);
+#[cfg(all(target_env = "gnu", fix_y2038))]
+weak!(fn __futimens64(c::c_int, *const LibcTimespec) -> c::c_int);
+
+/// Use a direct syscall (via libc) for `open`.
+///
+/// This is only currently necessary as a workaround for old glibc; see below.
+#[cfg(all(unix, target_env = "gnu"))]
+fn open_via_syscall(path: &CStr, oflags: OFlags, mode: Mode) -> io::Result<OwnedFd> {
+    // Linux on aarch64, loongarch64 and riscv64 has no `open` syscall so use
+    // `openat`.
+    #[cfg(any(
+        target_arch = "aarch64",
+        target_arch = "riscv32",
+        target_arch = "riscv64",
+        target_arch = "csky",
+        target_arch = "loongarch64"
+    ))]
+    {
+        openat_via_syscall(CWD, path, oflags, mode)
+    }
+
+    // Use the `open` syscall.
+    #[cfg(not(any(
+        target_arch = "aarch64",
+        target_arch = "riscv32",
+        target_arch = "riscv64",
+        target_arch = "csky",
+        target_arch = "loongarch64"
+    )))]
+    unsafe {
+        syscall! {
+            fn open(
+                pathname: *const c::c_char,
+                oflags: c::c_int,
+                mode: c::mode_t
+            ) via SYS_open -> c::c_int
+        }
+
+        ret_owned_fd(open(
+            c_str(path),
+            bitflags_bits!(oflags),
+            bitflags_bits!(mode),
+        ))
+    }
+}
+
+pub(crate) fn open(path: &CStr, oflags: OFlags, mode: Mode) -> io::Result<OwnedFd> {
+    // Work around <https://sourceware.org/bugzilla/show_bug.cgi?id=17523>.
+    // glibc versions before 2.25 don't handle `O_TMPFILE` correctly.
+    #[cfg(all(unix, target_env = "gnu", not(target_os = "hurd")))]
+    if oflags.contains(OFlags::TMPFILE) && crate::backend::if_glibc_is_less_than_2_25() {
+        return open_via_syscall(path, oflags, mode);
+    }
+
+    // On these platforms, `mode_t` is `u16` and can't be passed directly to a
+    // variadic function.
+    #[cfg(any(
+        apple,
+        freebsdlike,
+        all(target_os = "android", target_pointer_width = "32")
+    ))]
+    let mode: c::c_uint = mode.bits().into();
+
+    // Otherwise, cast to `mode_t` as that's what `open` is documented to take.
+    #[cfg(not(any(
+        apple,
+        freebsdlike,
+        all(target_os = "android", target_pointer_width = "32")
+    )))]
+    let mode: c::mode_t = mode.bits() as _;
+
+    unsafe { ret_owned_fd(c::open(c_str(path), bitflags_bits!(oflags), mode)) }
+}
+
+/// Use a direct syscall (via libc) for `openat`.
+///
+/// This is only currently necessary as a workaround for old glibc; see below.
+#[cfg(all(unix, target_env = "gnu", not(target_os = "hurd")))]
+fn openat_via_syscall(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    oflags: OFlags,
+    mode: Mode,
+) -> io::Result<OwnedFd> {
+    syscall! {
+        fn openat(
+            base_dirfd: c::c_int,
+            pathname: *const c::c_char,
+            oflags: c::c_int,
+            mode: c::mode_t
+        ) via SYS_openat -> c::c_int
+    }
+
+    unsafe {
+        ret_owned_fd(openat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            bitflags_bits!(oflags),
+            bitflags_bits!(mode),
+        ))
+    }
+}
+
+#[cfg(not(target_os = "redox"))]
+pub(crate) fn openat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    oflags: OFlags,
+    mode: Mode,
+) -> io::Result<OwnedFd> {
+    // Work around <https://sourceware.org/bugzilla/show_bug.cgi?id=17523>.
+    // glibc versions before 2.25 don't handle `O_TMPFILE` correctly.
+    #[cfg(all(unix, target_env = "gnu", not(target_os = "hurd")))]
+    if oflags.contains(OFlags::TMPFILE) && crate::backend::if_glibc_is_less_than_2_25() {
+        return openat_via_syscall(dirfd, path, oflags, mode);
+    }
+
+    // On these platforms, `mode_t` is `u16` and can't be passed directly to a
+    // variadic function.
+    #[cfg(any(
+        apple,
+        freebsdlike,
+        all(target_os = "android", target_pointer_width = "32")
+    ))]
+    let mode: c::c_uint = mode.bits().into();
+
+    // Otherwise, cast to `mode_t` as that's what `open` is documented to take.
+    #[cfg(not(any(
+        apple,
+        freebsdlike,
+        all(target_os = "android", target_pointer_width = "32")
+    )))]
+    let mode: c::mode_t = mode.bits() as _;
+
+    unsafe {
+        ret_owned_fd(c::openat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            bitflags_bits!(oflags),
+            mode,
+        ))
+    }
+}
+
+#[cfg(not(any(
+    solarish,
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "netbsd",
+    target_os = "nto",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi",
+)))]
+#[inline]
+pub(crate) fn statfs(filename: &CStr) -> io::Result<StatFs> {
+    unsafe {
+        let mut result = MaybeUninit::<StatFs>::uninit();
+        ret(c::statfs(c_str(filename), result.as_mut_ptr()))?;
+        Ok(result.assume_init())
+    }
+}
+
+#[cfg(not(any(target_os = "haiku", target_os = "redox", target_os = "wasi")))]
+#[inline]
+pub(crate) fn statvfs(filename: &CStr) -> io::Result<StatVfs> {
+    unsafe {
+        let mut result = MaybeUninit::<c::statvfs>::uninit();
+        ret(c::statvfs(c_str(filename), result.as_mut_ptr()))?;
+        Ok(libc_statvfs_to_statvfs(result.assume_init()))
+    }
+}
+
+#[cfg(feature = "alloc")]
+#[inline]
+pub(crate) fn readlink(path: &CStr, buf: &mut [u8]) -> io::Result<usize> {
+    unsafe {
+        ret_usize(
+            c::readlink(c_str(path), buf.as_mut_ptr().cast::<c::c_char>(), buf.len()) as isize,
+        )
+    }
+}
+
+#[cfg(not(target_os = "redox"))]
+#[inline]
+pub(crate) fn readlinkat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    buf: &mut [MaybeUninit<u8>],
+) -> io::Result<usize> {
+    unsafe {
+        ret_usize(c::readlinkat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            buf.as_mut_ptr().cast::<c::c_char>(),
+            buf.len(),
+        ) as isize)
+    }
+}
+
+pub(crate) fn mkdir(path: &CStr, mode: Mode) -> io::Result<()> {
+    unsafe { ret(c::mkdir(c_str(path), mode.bits() as c::mode_t)) }
+}
+
+#[cfg(not(target_os = "redox"))]
+pub(crate) fn mkdirat(dirfd: BorrowedFd<'_>, path: &CStr, mode: Mode) -> io::Result<()> {
+    unsafe {
+        ret(c::mkdirat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            mode.bits() as c::mode_t,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn getdents_uninit(
+    fd: BorrowedFd<'_>,
+    buf: &mut [MaybeUninit<u8>],
+) -> io::Result<usize> {
+    syscall! {
+        fn getdents64(
+            fd: c::c_int,
+            dirp: *mut c::c_void,
+            count: usize
+        ) via SYS_getdents64 -> c::ssize_t
+    }
+    unsafe {
+        ret_usize(getdents64(
+            borrowed_fd(fd),
+            buf.as_mut_ptr().cast::<c::c_void>(),
+            buf.len(),
+        ))
+    }
+}
+
+pub(crate) fn link(old_path: &CStr, new_path: &CStr) -> io::Result<()> {
+    unsafe { ret(c::link(c_str(old_path), c_str(new_path))) }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
+pub(crate) fn linkat(
+    old_dirfd: BorrowedFd<'_>,
+    old_path: &CStr,
+    new_dirfd: BorrowedFd<'_>,
+    new_path: &CStr,
+    flags: AtFlags,
+) -> io::Result<()> {
+    // macOS <= 10.9 lacks `linkat`.
+    #[cfg(target_os = "macos")]
+    unsafe {
+        weak! {
+            fn linkat(
+                c::c_int,
+                *const c::c_char,
+                c::c_int,
+                *const c::c_char,
+                c::c_int
+            ) -> c::c_int
+        }
+        // If we have `linkat`, use it.
+        if let Some(libc_linkat) = linkat.get() {
+            return ret(libc_linkat(
+                borrowed_fd(old_dirfd),
+                c_str(old_path),
+                borrowed_fd(new_dirfd),
+                c_str(new_path),
+                bitflags_bits!(flags),
+            ));
+        }
+        // Otherwise, see if we can emulate the `AT_FDCWD` case.
+        if borrowed_fd(old_dirfd) != c::AT_FDCWD || borrowed_fd(new_dirfd) != c::AT_FDCWD {
+            return Err(io::Errno::NOSYS);
+        }
+        if flags.intersects(!AtFlags::SYMLINK_FOLLOW) {
+            return Err(io::Errno::INVAL);
+        }
+        if !flags.is_empty() {
+            return Err(io::Errno::OPNOTSUPP);
+        }
+        ret(c::link(c_str(old_path), c_str(new_path)))
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    unsafe {
+        ret(c::linkat(
+            borrowed_fd(old_dirfd),
+            c_str(old_path),
+            borrowed_fd(new_dirfd),
+            c_str(new_path),
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+pub(crate) fn rmdir(path: &CStr) -> io::Result<()> {
+    unsafe { ret(c::rmdir(c_str(path))) }
+}
+
+pub(crate) fn unlink(path: &CStr) -> io::Result<()> {
+    unsafe { ret(c::unlink(c_str(path))) }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
+pub(crate) fn unlinkat(dirfd: BorrowedFd<'_>, path: &CStr, flags: AtFlags) -> io::Result<()> {
+    // macOS <= 10.9 lacks `unlinkat`.
+    #[cfg(target_os = "macos")]
+    unsafe {
+        weak! {
+            fn unlinkat(
+                c::c_int,
+                *const c::c_char,
+                c::c_int
+            ) -> c::c_int
+        }
+        // If we have `unlinkat`, use it.
+        if let Some(libc_unlinkat) = unlinkat.get() {
+            return ret(libc_unlinkat(
+                borrowed_fd(dirfd),
+                c_str(path),
+                bitflags_bits!(flags),
+            ));
+        }
+        // Otherwise, see if we can emulate the `AT_FDCWD` case.
+        if borrowed_fd(dirfd) != c::AT_FDCWD {
+            return Err(io::Errno::NOSYS);
+        }
+        if flags.intersects(!AtFlags::REMOVEDIR) {
+            return Err(io::Errno::INVAL);
+        }
+        if flags.contains(AtFlags::REMOVEDIR) {
+            ret(c::rmdir(c_str(path)))
+        } else {
+            ret(c::unlink(c_str(path)))
+        }
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    unsafe {
+        ret(c::unlinkat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+pub(crate) fn rename(old_path: &CStr, new_path: &CStr) -> io::Result<()> {
+    unsafe { ret(c::rename(c_str(old_path), c_str(new_path))) }
+}
+
+#[cfg(not(target_os = "redox"))]
+pub(crate) fn renameat(
+    old_dirfd: BorrowedFd<'_>,
+    old_path: &CStr,
+    new_dirfd: BorrowedFd<'_>,
+    new_path: &CStr,
+) -> io::Result<()> {
+    // macOS <= 10.9 lacks `renameat`.
+    #[cfg(target_os = "macos")]
+    unsafe {
+        weak! {
+            fn renameat(
+                c::c_int,
+                *const c::c_char,
+                c::c_int,
+                *const c::c_char
+            ) -> c::c_int
+        }
+        // If we have `renameat`, use it.
+        if let Some(libc_renameat) = renameat.get() {
+            return ret(libc_renameat(
+                borrowed_fd(old_dirfd),
+                c_str(old_path),
+                borrowed_fd(new_dirfd),
+                c_str(new_path),
+            ));
+        }
+        // Otherwise, see if we can emulate the `AT_FDCWD` case.
+        if borrowed_fd(old_dirfd) != c::AT_FDCWD || borrowed_fd(new_dirfd) != c::AT_FDCWD {
+            return Err(io::Errno::NOSYS);
+        }
+        ret(c::rename(c_str(old_path), c_str(new_path)))
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    unsafe {
+        ret(c::renameat(
+            borrowed_fd(old_dirfd),
+            c_str(old_path),
+            borrowed_fd(new_dirfd),
+            c_str(new_path),
+        ))
+    }
+}
+
+#[cfg(all(target_os = "linux", target_env = "gnu"))]
+pub(crate) fn renameat2(
+    old_dirfd: BorrowedFd<'_>,
+    old_path: &CStr,
+    new_dirfd: BorrowedFd<'_>,
+    new_path: &CStr,
+    flags: RenameFlags,
+) -> io::Result<()> {
+    // `renameat2` wasn't supported in glibc until 2.28.
+    weak_or_syscall! {
+        fn renameat2(
+            olddirfd: c::c_int,
+            oldpath: *const c::c_char,
+            newdirfd: c::c_int,
+            newpath: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_renameat2 -> c::c_int
+    }
+
+    unsafe {
+        ret(renameat2(
+            borrowed_fd(old_dirfd),
+            c_str(old_path),
+            borrowed_fd(new_dirfd),
+            c_str(new_path),
+            flags.bits(),
+        ))
+    }
+}
+
+#[cfg(any(
+    target_os = "android",
+    all(target_os = "linux", not(target_env = "gnu")),
+))]
+#[inline]
+pub(crate) fn renameat2(
+    old_dirfd: BorrowedFd<'_>,
+    old_path: &CStr,
+    new_dirfd: BorrowedFd<'_>,
+    new_path: &CStr,
+    flags: RenameFlags,
+) -> io::Result<()> {
+    // At present, `libc` only has `renameat2` defined for glibc. If we have
+    // no flags, we can use plain `renameat`, but otherwise we use `syscall!`.
+    // to call `renameat2` ourselves.
+    if flags.is_empty() {
+        renameat(old_dirfd, old_path, new_dirfd, new_path)
+    } else {
+        syscall! {
+            fn renameat2(
+                olddirfd: c::c_int,
+                oldpath: *const c::c_char,
+                newdirfd: c::c_int,
+                newpath: *const c::c_char,
+                flags: c::c_uint
+            ) via SYS_renameat2 -> c::c_int
+        }
+
+        unsafe {
+            ret(renameat2(
+                borrowed_fd(old_dirfd),
+                c_str(old_path),
+                borrowed_fd(new_dirfd),
+                c_str(new_path),
+                flags.bits(),
+            ))
+        }
+    }
+}
+
+pub(crate) fn symlink(old_path: &CStr, new_path: &CStr) -> io::Result<()> {
+    unsafe { ret(c::symlink(c_str(old_path), c_str(new_path))) }
+}
+
+#[cfg(not(target_os = "redox"))]
+pub(crate) fn symlinkat(
+    old_path: &CStr,
+    new_dirfd: BorrowedFd<'_>,
+    new_path: &CStr,
+) -> io::Result<()> {
+    unsafe {
+        ret(c::symlinkat(
+            c_str(old_path),
+            borrowed_fd(new_dirfd),
+            c_str(new_path),
+        ))
+    }
+}
+
+pub(crate) fn stat(path: &CStr) -> io::Result<Stat> {
+    // See the comments in `fstat` about using `crate::fs::statx` here.
+    #[cfg(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    ))]
+    {
+        match crate::fs::statx(
+            crate::fs::CWD,
+            path,
+            AtFlags::empty(),
+            StatxFlags::BASIC_STATS,
+        ) {
+            Ok(x) => statx_to_stat(x),
+            Err(io::Errno::NOSYS) => statat_old(crate::fs::CWD, path, AtFlags::empty()),
+            Err(err) => Err(err),
+        }
+    }
+
+    // Main version: libc is y2038 safe. Or, the platform is not y2038 safe and
+    // there's nothing practical we can do.
+    #[cfg(not(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    )))]
+    unsafe {
+        let mut stat = MaybeUninit::<Stat>::uninit();
+        ret(c::stat(c_str(path), stat.as_mut_ptr()))?;
+        Ok(stat.assume_init())
+    }
+}
+
+pub(crate) fn lstat(path: &CStr) -> io::Result<Stat> {
+    // See the comments in `fstat` about using `crate::fs::statx` here.
+    #[cfg(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    ))]
+    {
+        match crate::fs::statx(
+            crate::fs::CWD,
+            path,
+            AtFlags::SYMLINK_NOFOLLOW,
+            StatxFlags::BASIC_STATS,
+        ) {
+            Ok(x) => statx_to_stat(x),
+            Err(io::Errno::NOSYS) => statat_old(crate::fs::CWD, path, AtFlags::SYMLINK_NOFOLLOW),
+            Err(err) => Err(err),
+        }
+    }
+
+    // Main version: libc is y2038 safe. Or, the platform is not y2038 safe and
+    // there's nothing practical we can do.
+    #[cfg(not(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    )))]
+    unsafe {
+        let mut stat = MaybeUninit::<Stat>::uninit();
+        ret(c::lstat(c_str(path), stat.as_mut_ptr()))?;
+        Ok(stat.assume_init())
+    }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
+pub(crate) fn statat(dirfd: BorrowedFd<'_>, path: &CStr, flags: AtFlags) -> io::Result<Stat> {
+    // See the comments in `fstat` about using `crate::fs::statx` here.
+    #[cfg(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    ))]
+    {
+        match crate::fs::statx(dirfd, path, flags, StatxFlags::BASIC_STATS) {
+            Ok(x) => statx_to_stat(x),
+            Err(io::Errno::NOSYS) => statat_old(dirfd, path, flags),
+            Err(err) => Err(err),
+        }
+    }
+
+    // Main version: libc is y2038 safe. Or, the platform is not y2038 safe and
+    // there's nothing practical we can do.
+    #[cfg(not(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    )))]
+    unsafe {
+        let mut stat = MaybeUninit::<Stat>::uninit();
+        ret(c::fstatat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            stat.as_mut_ptr(),
+            bitflags_bits!(flags),
+        ))?;
+        Ok(stat.assume_init())
+    }
+}
+
+#[cfg(all(
+    linux_kernel,
+    any(
+        target_pointer_width = "32",
+        target_arch = "mips64",
+        target_arch = "mips64r6"
+    )
+))]
+fn statat_old(dirfd: BorrowedFd<'_>, path: &CStr, flags: AtFlags) -> io::Result<Stat> {
+    unsafe {
+        let mut result = MaybeUninit::<c::stat64>::uninit();
+        ret(c::fstatat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            result.as_mut_ptr(),
+            bitflags_bits!(flags),
+        ))?;
+        stat64_to_stat(result.assume_init())
+    }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "emscripten", target_os = "vita")))]
+pub(crate) fn access(path: &CStr, access: Access) -> io::Result<()> {
+    unsafe { ret(c::access(c_str(path), access.bits())) }
+}
+
+#[cfg(not(any(
+    target_os = "emscripten",
+    target_os = "espidf",
+    target_os = "redox",
+    target_os = "vita"
+)))]
+pub(crate) fn accessat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    access: Access,
+    flags: AtFlags,
+) -> io::Result<()> {
+    // macOS <= 10.9 lacks `faccessat`.
+    #[cfg(target_os = "macos")]
+    unsafe {
+        weak! {
+            fn faccessat(
+                c::c_int,
+                *const c::c_char,
+                c::c_int,
+                c::c_int
+            ) -> c::c_int
+        }
+        // If we have `faccessat`, use it.
+        if let Some(libc_faccessat) = faccessat.get() {
+            return ret(libc_faccessat(
+                borrowed_fd(dirfd),
+                c_str(path),
+                bitflags_bits!(access),
+                bitflags_bits!(flags),
+            ));
+        }
+        // Otherwise, see if we can emulate the `AT_FDCWD` case.
+        if borrowed_fd(dirfd) != c::AT_FDCWD {
+            return Err(io::Errno::NOSYS);
+        }
+        if flags.intersects(!(AtFlags::EACCESS | AtFlags::SYMLINK_NOFOLLOW)) {
+            return Err(io::Errno::INVAL);
+        }
+        if !flags.is_empty() {
+            return Err(io::Errno::OPNOTSUPP);
+        }
+        ret(c::access(c_str(path), bitflags_bits!(access)))
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    unsafe {
+        ret(c::faccessat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            bitflags_bits!(access),
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+#[cfg(target_os = "emscripten")]
+pub(crate) fn access(_path: &CStr, _access: Access) -> io::Result<()> {
+    Ok(())
+}
+
+#[cfg(target_os = "emscripten")]
+pub(crate) fn accessat(
+    _dirfd: BorrowedFd<'_>,
+    _path: &CStr,
+    _access: Access,
+    _flags: AtFlags,
+) -> io::Result<()> {
+    Ok(())
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "redox", target_os = "vita")))]
+pub(crate) fn utimensat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    times: &Timestamps,
+    flags: AtFlags,
+) -> io::Result<()> {
+    // Old 32-bit version: libc has `utimensat` but it is not y2038 safe by
+    // default. But there may be a `__utimensat16` we can use.
+    #[cfg(fix_y2038)]
+    {
+        #[cfg(target_env = "gnu")]
+        if let Some(libc_utimensat) = __utimensat64.get() {
+            let libc_times: [LibcTimespec; 2] = [
+                times.last_access.clone().into(),
+                times.last_modification.clone().into(),
+            ];
+
+            unsafe {
+                return ret(libc_utimensat(
+                    borrowed_fd(dirfd),
+                    c_str(path),
+                    libc_times.as_ptr(),
+                    bitflags_bits!(flags),
+                ));
+            }
+        }
+
+        utimensat_old(dirfd, path, times, flags)
+    }
+
+    // Main version: libc is y2038 safe and has `utimensat`. Or, the platform
+    // is not y2038 safe and there's nothing practical we can do.
+    #[cfg(not(any(apple, fix_y2038)))]
+    unsafe {
+        use crate::utils::as_ptr;
+
+        ret(c::utimensat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            as_ptr(times).cast(),
+            bitflags_bits!(flags),
+        ))
+    }
+
+    // Apple version: `utimensat` was introduced in macOS 10.13.
+    #[cfg(apple)]
+    unsafe {
+        use crate::utils::as_ptr;
+
+        // ABI details
+        weak! {
+            fn utimensat(
+                c::c_int,
+                *const c::c_char,
+                *const c::timespec,
+                c::c_int
+            ) -> c::c_int
+        }
+        extern "C" {
+            fn setattrlist(
+                path: *const c::c_char,
+                attr_list: *const Attrlist,
+                attr_buf: *const c::c_void,
+                attr_buf_size: c::size_t,
+                options: c::c_ulong,
+            ) -> c::c_int;
+        }
+        const FSOPT_NOFOLLOW: c::c_ulong = 0x0000_0001;
+
+        // If we have `utimensat`, use it.
+        if let Some(have_utimensat) = utimensat.get() {
+            return ret(have_utimensat(
+                borrowed_fd(dirfd),
+                c_str(path),
+                as_ptr(times).cast(),
+                bitflags_bits!(flags),
+            ));
+        }
+
+        // `setattrlistat` was introduced in 10.13 along with `utimensat`, so
+        // if we don't have `utimensat`, we don't have `setattrlistat` either.
+        // Emulate it using `fork`, and `fchdir` and [`setattrlist`].
+        //
+        // [`setattrlist`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setattrlist.2.html
+        match c::fork() {
+            -1 => Err(io::Errno::IO),
+            0 => {
+                if c::fchdir(borrowed_fd(dirfd)) != 0 {
+                    let code = match libc_errno::errno().0 {
+                        c::EACCES => 2,
+                        c::ENOTDIR => 3,
+                        _ => 1,
+                    };
+                    c::_exit(code);
+                }
+
+                let mut flags_arg = 0;
+                if flags.contains(AtFlags::SYMLINK_NOFOLLOW) {
+                    flags_arg |= FSOPT_NOFOLLOW;
+                }
+
+                let (attrbuf_size, times, attrs) = times_to_attrlist(times);
+
+                if setattrlist(
+                    c_str(path),
+                    &attrs,
+                    as_ptr(&times).cast(),
+                    attrbuf_size,
+                    flags_arg,
+                ) != 0
+                {
+                    // Translate expected `errno` codes into ad-hoc integer
+                    // values suitable for exit statuses.
+                    let code = match libc_errno::errno().0 {
+                        c::EACCES => 2,
+                        c::ENOTDIR => 3,
+                        c::EPERM => 4,
+                        c::EROFS => 5,
+                        c::ELOOP => 6,
+                        c::ENOENT => 7,
+                        c::ENAMETOOLONG => 8,
+                        c::EINVAL => 9,
+                        c::ESRCH => 10,
+                        c::ENOTSUP => 11,
+                        _ => 1,
+                    };
+                    c::_exit(code);
+                }
+
+                c::_exit(0);
+            }
+            child_pid => {
+                let mut wstatus = 0;
+                let _ = ret_c_int(c::waitpid(child_pid, &mut wstatus, 0))?;
+                if c::WIFEXITED(wstatus) {
+                    // Translate our ad-hoc exit statuses back to `errno`
+                    // codes.
+                    match c::WEXITSTATUS(wstatus) {
+                        0 => Ok(()),
+                        2 => Err(io::Errno::ACCESS),
+                        3 => Err(io::Errno::NOTDIR),
+                        4 => Err(io::Errno::PERM),
+                        5 => Err(io::Errno::ROFS),
+                        6 => Err(io::Errno::LOOP),
+                        7 => Err(io::Errno::NOENT),
+                        8 => Err(io::Errno::NAMETOOLONG),
+                        9 => Err(io::Errno::INVAL),
+                        10 => Err(io::Errno::SRCH),
+                        11 => Err(io::Errno::NOTSUP),
+                        _ => Err(io::Errno::IO),
+                    }
+                } else {
+                    Err(io::Errno::IO)
+                }
+            }
+        }
+    }
+}
+
+#[cfg(fix_y2038)]
+fn utimensat_old(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    times: &Timestamps,
+    flags: AtFlags,
+) -> io::Result<()> {
+    let old_times = [
+        c::timespec {
+            tv_sec: times
+                .last_access
+                .tv_sec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+            tv_nsec: times
+                .last_access
+                .tv_nsec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+        },
+        c::timespec {
+            tv_sec: times
+                .last_modification
+                .tv_sec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+            tv_nsec: times
+                .last_modification
+                .tv_nsec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+        },
+    ];
+    unsafe {
+        ret(c::utimensat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            old_times.as_ptr(),
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+#[cfg(not(target_os = "wasi"))]
+pub(crate) fn chmod(path: &CStr, mode: Mode) -> io::Result<()> {
+    unsafe { ret(c::chmod(c_str(path), mode.bits() as c::mode_t)) }
+}
+
+#[cfg(not(any(
+    linux_kernel,
+    target_os = "espidf",
+    target_os = "redox",
+    target_os = "wasi"
+)))]
+pub(crate) fn chmodat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    mode: Mode,
+    flags: AtFlags,
+) -> io::Result<()> {
+    unsafe {
+        ret(c::fchmodat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            mode.bits() as c::mode_t,
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn chmodat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    mode: Mode,
+    flags: AtFlags,
+) -> io::Result<()> {
+    // Linux's `fchmodat` does not have a flags argument.
+    //
+    // Use `c::syscall` rather than `c::fchmodat` because some libc
+    // implementations, such as musl, add extra logic to `fchmod` to emulate
+    // support for `AT_SYMLINK_NOFOLLOW`, which uses `/proc` outside our
+    // control.
+    syscall! {
+        fn fchmodat(
+            base_dirfd: c::c_int,
+            pathname: *const c::c_char,
+            mode: c::mode_t
+        ) via SYS_fchmodat -> c::c_int
+    }
+    if flags == AtFlags::SYMLINK_NOFOLLOW {
+        return Err(io::Errno::OPNOTSUPP);
+    }
+    if !flags.is_empty() {
+        return Err(io::Errno::INVAL);
+    }
+    unsafe {
+        ret(fchmodat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            mode.bits() as c::mode_t,
+        ))
+    }
+}
+
+#[cfg(apple)]
+pub(crate) fn fclonefileat(
+    srcfd: BorrowedFd<'_>,
+    dst_dirfd: BorrowedFd<'_>,
+    dst: &CStr,
+    flags: CloneFlags,
+) -> io::Result<()> {
+    syscall! {
+        fn fclonefileat(
+            srcfd: BorrowedFd<'_>,
+            dst_dirfd: BorrowedFd<'_>,
+            dst: *const c::c_char,
+            flags: c::c_int
+        ) via SYS_fclonefileat -> c::c_int
+    }
+
+    unsafe {
+        ret(fclonefileat(
+            srcfd,
+            dst_dirfd,
+            c_str(dst),
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "redox", target_os = "wasi")))]
+pub(crate) fn chownat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    owner: Option<Uid>,
+    group: Option<Gid>,
+    flags: AtFlags,
+) -> io::Result<()> {
+    unsafe {
+        let (ow, gr) = crate::ugid::translate_fchown_args(owner, group);
+        ret(c::fchownat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            ow,
+            gr,
+            bitflags_bits!(flags),
+        ))
+    }
+}
+
+#[cfg(not(any(
+    apple,
+    target_os = "espidf",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi"
+)))]
+pub(crate) fn mknodat(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    file_type: FileType,
+    mode: Mode,
+    dev: Dev,
+) -> io::Result<()> {
+    unsafe {
+        ret(c::mknodat(
+            borrowed_fd(dirfd),
+            c_str(path),
+            (mode.bits() | file_type.as_raw_mode()) as c::mode_t,
+            dev.try_into().map_err(|_e| io::Errno::PERM)?,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn copy_file_range(
+    fd_in: BorrowedFd<'_>,
+    off_in: Option<&mut u64>,
+    fd_out: BorrowedFd<'_>,
+    off_out: Option<&mut u64>,
+    len: usize,
+) -> io::Result<usize> {
+    syscall! {
+        fn copy_file_range(
+            fd_in: c::c_int,
+            off_in: *mut c::loff_t,
+            fd_out: c::c_int,
+            off_out: *mut c::loff_t,
+            len: usize,
+            flags: c::c_uint
+        ) via SYS_copy_file_range -> c::ssize_t
+    }
+
+    let mut off_in_val: c::loff_t = 0;
+    let mut off_out_val: c::loff_t = 0;
+    // Silently cast; we'll get `EINVAL` if the value is negative.
+    let off_in_ptr = if let Some(off_in) = &off_in {
+        off_in_val = **off_in as i64;
+        &mut off_in_val
+    } else {
+        null_mut()
+    };
+    let off_out_ptr = if let Some(off_out) = &off_out {
+        off_out_val = **off_out as i64;
+        &mut off_out_val
+    } else {
+        null_mut()
+    };
+    let copied = unsafe {
+        ret_usize(copy_file_range(
+            borrowed_fd(fd_in),
+            off_in_ptr,
+            borrowed_fd(fd_out),
+            off_out_ptr,
+            len,
+            0, // no flags are defined yet
+        ))?
+    };
+    if let Some(off_in) = off_in {
+        *off_in = off_in_val as u64;
+    }
+    if let Some(off_out) = off_out {
+        *off_out = off_out_val as u64;
+    }
+    Ok(copied)
+}
+
+#[cfg(not(any(
+    apple,
+    netbsdlike,
+    solarish,
+    target_os = "dragonfly",
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "redox",
+    target_os = "vita",
+)))]
+pub(crate) fn fadvise(fd: BorrowedFd<'_>, offset: u64, len: u64, advice: Advice) -> io::Result<()> {
+    let offset = offset as i64;
+    let len = len as i64;
+
+    // FreeBSD returns `EINVAL` on invalid offsets; emulate the POSIX behavior.
+    #[cfg(target_os = "freebsd")]
+    let offset = if (offset as i64) < 0 {
+        i64::MAX
+    } else {
+        offset
+    };
+
+    // FreeBSD returns `EINVAL` on overflow; emulate the POSIX behavior.
+    #[cfg(target_os = "freebsd")]
+    let len = if len > 0 && offset.checked_add(len).is_none() {
+        i64::MAX - offset
+    } else {
+        len
+    };
+
+    let err = unsafe { c::posix_fadvise(borrowed_fd(fd), offset, len, advice as c::c_int) };
+
+    // `posix_fadvise` returns its error status rather than using `errno`.
+    if err == 0 {
+        Ok(())
+    } else {
+        Err(io::Errno(err))
+    }
+}
+
+pub(crate) fn fcntl_getfl(fd: BorrowedFd<'_>) -> io::Result<OFlags> {
+    let flags = unsafe { ret_c_int(c::fcntl(borrowed_fd(fd), c::F_GETFL))? };
+    Ok(OFlags::from_bits_retain(bitcast!(flags)))
+}
+
+pub(crate) fn fcntl_setfl(fd: BorrowedFd<'_>, flags: OFlags) -> io::Result<()> {
+    unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_SETFL, flags.bits())) }
+}
+
+#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
+pub(crate) fn fcntl_get_seals(fd: BorrowedFd<'_>) -> io::Result<SealFlags> {
+    let flags = unsafe { ret_c_int(c::fcntl(borrowed_fd(fd), c::F_GET_SEALS))? };
+    Ok(SealFlags::from_bits_retain(bitcast!(flags)))
+}
+
+#[cfg(any(linux_kernel, target_os = "freebsd", target_os = "fuchsia"))]
+pub(crate) fn fcntl_add_seals(fd: BorrowedFd<'_>, seals: SealFlags) -> io::Result<()> {
+    unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_ADD_SEALS, seals.bits())) }
+}
+
+#[cfg(not(any(
+    target_os = "emscripten",
+    target_os = "espidf",
+    target_os = "fuchsia",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi"
+)))]
+#[inline]
+pub(crate) fn fcntl_lock(fd: BorrowedFd<'_>, operation: FlockOperation) -> io::Result<()> {
+    use c::{flock, F_RDLCK, F_SETLK, F_SETLKW, F_UNLCK, F_WRLCK, SEEK_SET};
+
+    let (cmd, l_type) = match operation {
+        FlockOperation::LockShared => (F_SETLKW, F_RDLCK),
+        FlockOperation::LockExclusive => (F_SETLKW, F_WRLCK),
+        FlockOperation::Unlock => (F_SETLKW, F_UNLCK),
+        FlockOperation::NonBlockingLockShared => (F_SETLK, F_RDLCK),
+        FlockOperation::NonBlockingLockExclusive => (F_SETLK, F_WRLCK),
+        FlockOperation::NonBlockingUnlock => (F_SETLK, F_UNLCK),
+    };
+
+    unsafe {
+        let mut lock: flock = core::mem::zeroed();
+        lock.l_type = l_type as _;
+
+        // When `l_len` is zero, this locks all the bytes from
+        // `l_whence`/`l_start` to the end of the file, even as the
+        // file grows dynamically.
+        lock.l_whence = SEEK_SET as _;
+        lock.l_start = 0;
+        lock.l_len = 0;
+
+        ret(c::fcntl(borrowed_fd(fd), cmd, &lock))
+    }
+}
+
+pub(crate) fn seek(fd: BorrowedFd<'_>, pos: SeekFrom) -> io::Result<u64> {
+    let (whence, offset) = match pos {
+        SeekFrom::Start(pos) => {
+            let pos: u64 = pos;
+            // Silently cast; we'll get `EINVAL` if the value is negative.
+            (c::SEEK_SET, pos as i64)
+        }
+        SeekFrom::End(offset) => (c::SEEK_END, offset),
+        SeekFrom::Current(offset) => (c::SEEK_CUR, offset),
+        #[cfg(any(apple, freebsdlike, linux_kernel, solarish))]
+        SeekFrom::Data(offset) => (c::SEEK_DATA, offset),
+        #[cfg(any(apple, freebsdlike, linux_kernel, solarish))]
+        SeekFrom::Hole(offset) => (c::SEEK_HOLE, offset),
+    };
+
+    // ESP-IDF and Vita don't support 64-bit offsets.
+    #[cfg(any(target_os = "espidf", target_os = "vita"))]
+    let offset: i32 = offset.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+
+    let offset = unsafe { ret_off_t(c::lseek(borrowed_fd(fd), offset, whence))? };
+    Ok(offset as u64)
+}
+
+pub(crate) fn tell(fd: BorrowedFd<'_>) -> io::Result<u64> {
+    let offset = unsafe { ret_off_t(c::lseek(borrowed_fd(fd), 0, c::SEEK_CUR))? };
+    Ok(offset as u64)
+}
+
+#[cfg(not(any(linux_kernel, target_os = "wasi")))]
+pub(crate) fn fchmod(fd: BorrowedFd<'_>, mode: Mode) -> io::Result<()> {
+    unsafe { ret(c::fchmod(borrowed_fd(fd), bitflags_bits!(mode))) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fchmod(fd: BorrowedFd<'_>, mode: Mode) -> io::Result<()> {
+    // Use `c::syscall` rather than `c::fchmod` because some libc
+    // implementations, such as musl, add extra logic to `fchmod` to emulate
+    // support for `O_PATH`, which uses `/proc` outside our control and
+    // interferes with our own use of `O_PATH`.
+    syscall! {
+        fn fchmod(
+            fd: c::c_int,
+            mode: c::mode_t
+        ) via SYS_fchmod -> c::c_int
+    }
+    unsafe { ret(fchmod(borrowed_fd(fd), mode.bits() as c::mode_t)) }
+}
+
+#[cfg(not(target_os = "wasi"))]
+pub(crate) fn chown(path: &CStr, owner: Option<Uid>, group: Option<Gid>) -> io::Result<()> {
+    unsafe {
+        let (ow, gr) = crate::ugid::translate_fchown_args(owner, group);
+        ret(c::chown(c_str(path), ow, gr))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fchown(fd: BorrowedFd<'_>, owner: Option<Uid>, group: Option<Gid>) -> io::Result<()> {
+    // Use `c::syscall` rather than `c::fchown` because some libc
+    // implementations, such as musl, add extra logic to `fchown` to emulate
+    // support for `O_PATH`, which uses `/proc` outside our control and
+    // interferes with our own use of `O_PATH`.
+    syscall! {
+        fn fchown(
+            fd: c::c_int,
+            owner: c::uid_t,
+            group: c::gid_t
+        ) via SYS_fchown -> c::c_int
+    }
+    unsafe {
+        let (ow, gr) = crate::ugid::translate_fchown_args(owner, group);
+        ret(fchown(borrowed_fd(fd), ow, gr))
+    }
+}
+
+#[cfg(not(any(linux_kernel, target_os = "wasi")))]
+pub(crate) fn fchown(fd: BorrowedFd<'_>, owner: Option<Uid>, group: Option<Gid>) -> io::Result<()> {
+    unsafe {
+        let (ow, gr) = crate::ugid::translate_fchown_args(owner, group);
+        ret(c::fchown(borrowed_fd(fd), ow, gr))
+    }
+}
+
+#[cfg(not(any(
+    target_os = "espidf",
+    target_os = "solaris",
+    target_os = "vita",
+    target_os = "wasi"
+)))]
+pub(crate) fn flock(fd: BorrowedFd<'_>, operation: FlockOperation) -> io::Result<()> {
+    unsafe { ret(c::flock(borrowed_fd(fd), operation as c::c_int)) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn syncfs(fd: BorrowedFd<'_>) -> io::Result<()> {
+    // Some versions of Android libc lack a `syncfs` function.
+    #[cfg(target_os = "android")]
+    syscall! {
+        fn syncfs(fd: c::c_int) via SYS_syncfs -> c::c_int
+    }
+
+    // `syncfs` was added to glibc in 2.20.
+    #[cfg(not(target_os = "android"))]
+    weak_or_syscall! {
+        fn syncfs(fd: c::c_int) via SYS_syncfs -> c::c_int
+    }
+
+    unsafe { ret(syncfs(borrowed_fd(fd))) }
+}
+
+#[cfg(not(any(
+    target_os = "espidf",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi"
+)))]
+pub(crate) fn sync() {
+    unsafe { c::sync() }
+}
+
+pub(crate) fn fstat(fd: BorrowedFd<'_>) -> io::Result<Stat> {
+    // 32-bit and mips64 Linux: `struct stat64` is not y2038 compatible; use
+    // `statx`.
+    //
+    // And, some old platforms don't support `statx`, and some fail with a
+    // confusing error code, so we call `crate::fs::statx` to handle that. If
+    // `statx` isn't available, fall back to the buggy system call.
+    #[cfg(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    ))]
+    {
+        match crate::fs::statx(fd, cstr!(""), AtFlags::EMPTY_PATH, StatxFlags::BASIC_STATS) {
+            Ok(x) => statx_to_stat(x),
+            Err(io::Errno::NOSYS) => fstat_old(fd),
+            Err(err) => Err(err),
+        }
+    }
+
+    // Main version: libc is y2038 safe. Or, the platform is not y2038 safe and
+    // there's nothing practical we can do.
+    #[cfg(not(all(
+        linux_kernel,
+        any(
+            target_pointer_width = "32",
+            target_arch = "mips64",
+            target_arch = "mips64r6"
+        )
+    )))]
+    unsafe {
+        let mut stat = MaybeUninit::<Stat>::uninit();
+        ret(c::fstat(borrowed_fd(fd), stat.as_mut_ptr()))?;
+        Ok(stat.assume_init())
+    }
+}
+
+#[cfg(all(
+    linux_kernel,
+    any(
+        target_pointer_width = "32",
+        target_arch = "mips64",
+        target_arch = "mips64r6"
+    )
+))]
+fn fstat_old(fd: BorrowedFd<'_>) -> io::Result<Stat> {
+    unsafe {
+        let mut result = MaybeUninit::<c::stat64>::uninit();
+        ret(c::fstat(borrowed_fd(fd), result.as_mut_ptr()))?;
+        stat64_to_stat(result.assume_init())
+    }
+}
+
+#[cfg(not(any(
+    solarish,
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "netbsd",
+    target_os = "nto",
+    target_os = "redox",
+    target_os = "vita",
+    target_os = "wasi",
+)))]
+pub(crate) fn fstatfs(fd: BorrowedFd<'_>) -> io::Result<StatFs> {
+    let mut statfs = MaybeUninit::<StatFs>::uninit();
+    unsafe {
+        ret(c::fstatfs(borrowed_fd(fd), statfs.as_mut_ptr()))?;
+        Ok(statfs.assume_init())
+    }
+}
+
+#[cfg(not(any(target_os = "haiku", target_os = "redox", target_os = "wasi")))]
+pub(crate) fn fstatvfs(fd: BorrowedFd<'_>) -> io::Result<StatVfs> {
+    let mut statvfs = MaybeUninit::<c::statvfs>::uninit();
+    unsafe {
+        ret(c::fstatvfs(borrowed_fd(fd), statvfs.as_mut_ptr()))?;
+        Ok(libc_statvfs_to_statvfs(statvfs.assume_init()))
+    }
+}
+
+#[cfg(not(any(target_os = "haiku", target_os = "redox", target_os = "wasi")))]
+fn libc_statvfs_to_statvfs(from: c::statvfs) -> StatVfs {
+    StatVfs {
+        f_bsize: from.f_bsize as u64,
+        f_frsize: from.f_frsize as u64,
+        f_blocks: from.f_blocks as u64,
+        f_bfree: from.f_bfree as u64,
+        f_bavail: from.f_bavail as u64,
+        f_files: from.f_files as u64,
+        f_ffree: from.f_ffree as u64,
+        f_favail: from.f_ffree as u64,
+        #[cfg(not(target_os = "aix"))]
+        f_fsid: from.f_fsid as u64,
+        #[cfg(target_os = "aix")]
+        f_fsid: ((from.f_fsid.val[0] as u64) << 32) | from.f_fsid.val[1],
+        f_flag: StatVfsMountFlags::from_bits_retain(from.f_flag as u64),
+        f_namemax: from.f_namemax as u64,
+    }
+}
+
+#[cfg(not(any(target_os = "espidf", target_os = "vita")))]
+pub(crate) fn futimens(fd: BorrowedFd<'_>, times: &Timestamps) -> io::Result<()> {
+    // Old 32-bit version: libc has `futimens` but it is not y2038 safe by
+    // default. But there may be a `__futimens64` we can use.
+    #[cfg(fix_y2038)]
+    {
+        #[cfg(target_env = "gnu")]
+        if let Some(libc_futimens) = __futimens64.get() {
+            let libc_times: [LibcTimespec; 2] = [
+                times.last_access.clone().into(),
+                times.last_modification.clone().into(),
+            ];
+
+            unsafe {
+                return ret(libc_futimens(borrowed_fd(fd), libc_times.as_ptr()));
+            }
+        }
+
+        futimens_old(fd, times)
+    }
+
+    // Main version: libc is y2038 safe and has `futimens`. Or, the platform
+    // is not y2038 safe and there's nothing practical we can do.
+    #[cfg(not(any(apple, fix_y2038)))]
+    unsafe {
+        use crate::utils::as_ptr;
+
+        ret(c::futimens(borrowed_fd(fd), as_ptr(times).cast()))
+    }
+
+    // Apple version: `futimens` was introduced in macOS 10.13.
+    #[cfg(apple)]
+    unsafe {
+        use crate::utils::as_ptr;
+
+        // ABI details.
+        weak! {
+            fn futimens(c::c_int, *const c::timespec) -> c::c_int
+        }
+        extern "C" {
+            fn fsetattrlist(
+                fd: c::c_int,
+                attr_list: *const Attrlist,
+                attr_buf: *const c::c_void,
+                attr_buf_size: c::size_t,
+                options: c::c_ulong,
+            ) -> c::c_int;
+        }
+
+        // If we have `futimens`, use it.
+        if let Some(have_futimens) = futimens.get() {
+            return ret(have_futimens(borrowed_fd(fd), as_ptr(times).cast()));
+        }
+
+        // Otherwise use `fsetattrlist`.
+        let (attrbuf_size, times, attrs) = times_to_attrlist(times);
+
+        ret(fsetattrlist(
+            borrowed_fd(fd),
+            &attrs,
+            as_ptr(&times).cast(),
+            attrbuf_size,
+            0,
+        ))
+    }
+}
+
+#[cfg(fix_y2038)]
+fn futimens_old(fd: BorrowedFd<'_>, times: &Timestamps) -> io::Result<()> {
+    let old_times = [
+        c::timespec {
+            tv_sec: times
+                .last_access
+                .tv_sec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+            tv_nsec: times
+                .last_access
+                .tv_nsec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+        },
+        c::timespec {
+            tv_sec: times
+                .last_modification
+                .tv_sec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+            tv_nsec: times
+                .last_modification
+                .tv_nsec
+                .try_into()
+                .map_err(|_| io::Errno::OVERFLOW)?,
+        },
+    ];
+
+    unsafe { ret(c::futimens(borrowed_fd(fd), old_times.as_ptr())) }
+}
+
+#[cfg(not(any(
+    apple,
+    netbsdlike,
+    solarish,
+    target_os = "aix",
+    target_os = "dragonfly",
+    target_os = "espidf",
+    target_os = "nto",
+    target_os = "redox",
+    target_os = "vita",
+)))]
+pub(crate) fn fallocate(
+    fd: BorrowedFd<'_>,
+    mode: FallocateFlags,
+    offset: u64,
+    len: u64,
+) -> io::Result<()> {
+    // Silently cast; we'll get `EINVAL` if the value is negative.
+    let offset = offset as i64;
+    let len = len as i64;
+
+    #[cfg(any(linux_kernel, target_os = "fuchsia"))]
+    unsafe {
+        ret(c::fallocate(
+            borrowed_fd(fd),
+            bitflags_bits!(mode),
+            offset,
+            len,
+        ))
+    }
+
+    #[cfg(not(any(linux_kernel, target_os = "fuchsia")))]
+    {
+        assert!(mode.is_empty());
+        let err = unsafe { c::posix_fallocate(borrowed_fd(fd), offset, len) };
+
+        // `posix_fallocate` returns its error status rather than using
+        // `errno`.
+        if err == 0 {
+            Ok(())
+        } else {
+            Err(io::Errno(err))
+        }
+    }
+}
+
+#[cfg(apple)]
+pub(crate) fn fallocate(
+    fd: BorrowedFd<'_>,
+    mode: FallocateFlags,
+    offset: u64,
+    len: u64,
+) -> io::Result<()> {
+    let offset: i64 = offset.try_into().map_err(|_e| io::Errno::INVAL)?;
+    let len = len as i64;
+
+    assert!(mode.is_empty());
+
+    let new_len = offset.checked_add(len).ok_or(io::Errno::FBIG)?;
+    let mut store = c::fstore_t {
+        fst_flags: c::F_ALLOCATECONTIG,
+        fst_posmode: c::F_PEOFPOSMODE,
+        fst_offset: 0,
+        fst_length: new_len,
+        fst_bytesalloc: 0,
+    };
+    unsafe {
+        if c::fcntl(borrowed_fd(fd), c::F_PREALLOCATE, &store) == -1 {
+            // Unable to allocate contiguous disk space; attempt to allocate
+            // non-contiguously.
+            store.fst_flags = c::F_ALLOCATEALL;
+            let _ = ret_c_int(c::fcntl(borrowed_fd(fd), c::F_PREALLOCATE, &store))?;
+        }
+        ret(c::ftruncate(borrowed_fd(fd), new_len))
+    }
+}
+
+pub(crate) fn fsync(fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe { ret(c::fsync(borrowed_fd(fd))) }
+}
+
+#[cfg(not(any(
+    apple,
+    target_os = "dragonfly",
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "redox",
+    target_os = "vita",
+)))]
+pub(crate) fn fdatasync(fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe { ret(c::fdatasync(borrowed_fd(fd))) }
+}
+
+pub(crate) fn ftruncate(fd: BorrowedFd<'_>, length: u64) -> io::Result<()> {
+    let length = length.try_into().map_err(|_overflow_err| io::Errno::FBIG)?;
+    unsafe { ret(c::ftruncate(borrowed_fd(fd), length)) }
+}
+
+#[cfg(any(linux_kernel, target_os = "freebsd"))]
+pub(crate) fn memfd_create(name: &CStr, flags: MemfdFlags) -> io::Result<OwnedFd> {
+    #[cfg(target_os = "freebsd")]
+    weakcall! {
+        fn memfd_create(
+            name: *const c::c_char,
+            flags: c::c_uint
+        ) -> c::c_int
+    }
+
+    #[cfg(linux_kernel)]
+    weak_or_syscall! {
+        fn memfd_create(
+            name: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_memfd_create -> c::c_int
+    }
+
+    unsafe { ret_owned_fd(memfd_create(c_str(name), bitflags_bits!(flags))) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn openat2(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    oflags: OFlags,
+    mode: Mode,
+    resolve: ResolveFlags,
+) -> io::Result<OwnedFd> {
+    use linux_raw_sys::general::open_how;
+
+    syscall! {
+        fn openat2(
+            base_dirfd: c::c_int,
+            pathname: *const c::c_char,
+            how: *mut open_how,
+            size: usize
+        ) via SYS_OPENAT2 -> c::c_int
+    }
+
+    let oflags = oflags.bits();
+    let mut open_how = open_how {
+        flags: u64::from(oflags),
+        mode: u64::from(mode.bits()),
+        resolve: resolve.bits(),
+    };
+
+    unsafe {
+        ret_owned_fd(openat2(
+            borrowed_fd(dirfd),
+            c_str(path),
+            &mut open_how,
+            size_of::<open_how>(),
+        ))
+    }
+}
+#[cfg(all(linux_kernel, target_pointer_width = "32"))]
+const SYS_OPENAT2: i32 = 437;
+#[cfg(all(linux_kernel, target_pointer_width = "64"))]
+const SYS_OPENAT2: i64 = 437;
+
+#[cfg(target_os = "linux")]
+pub(crate) fn sendfile(
+    out_fd: BorrowedFd<'_>,
+    in_fd: BorrowedFd<'_>,
+    offset: Option<&mut u64>,
+    count: usize,
+) -> io::Result<usize> {
+    unsafe {
+        ret_usize(c::sendfile64(
+            borrowed_fd(out_fd),
+            borrowed_fd(in_fd),
+            offset.map_or(null_mut(), crate::utils::as_mut_ptr).cast(),
+            count,
+        ))
+    }
+}
+
+/// Convert from a Linux `statx` value to rustix's `Stat`.
+#[cfg(all(linux_kernel, target_pointer_width = "32"))]
+fn statx_to_stat(x: crate::fs::Statx) -> io::Result<Stat> {
+    Ok(Stat {
+        st_dev: crate::fs::makedev(x.stx_dev_major, x.stx_dev_minor).into(),
+        st_mode: x.stx_mode.into(),
+        st_nlink: x.stx_nlink.into(),
+        st_uid: x.stx_uid.into(),
+        st_gid: x.stx_gid.into(),
+        st_rdev: crate::fs::makedev(x.stx_rdev_major, x.stx_rdev_minor).into(),
+        st_size: x.stx_size.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_blksize: x.stx_blksize.into(),
+        st_blocks: x.stx_blocks.into(),
+        st_atime: x
+            .stx_atime
+            .tv_sec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_atime_nsec: x.stx_atime.tv_nsec as _,
+        st_mtime: x
+            .stx_mtime
+            .tv_sec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_mtime_nsec: x.stx_mtime.tv_nsec as _,
+        st_ctime: x
+            .stx_ctime
+            .tv_sec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_ctime_nsec: x.stx_ctime.tv_nsec as _,
+        st_ino: x.stx_ino.into(),
+    })
+}
+
+/// Convert from a Linux `statx` value to rustix's `Stat`.
+///
+/// mips64' `struct stat64` in libc has private fields, and `stx_blocks`
+#[cfg(all(linux_kernel, any(target_arch = "mips64", target_arch = "mips64r6")))]
+fn statx_to_stat(x: crate::fs::Statx) -> io::Result<Stat> {
+    let mut result: Stat = unsafe { core::mem::zeroed() };
+
+    result.st_dev = crate::fs::makedev(x.stx_dev_major, x.stx_dev_minor);
+    result.st_mode = x.stx_mode.into();
+    result.st_nlink = x.stx_nlink.into();
+    result.st_uid = x.stx_uid.into();
+    result.st_gid = x.stx_gid.into();
+    result.st_rdev = crate::fs::makedev(x.stx_rdev_major, x.stx_rdev_minor);
+    result.st_size = x.stx_size.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_blksize = x.stx_blksize.into();
+    result.st_blocks = x.stx_blocks.try_into().map_err(|_e| io::Errno::OVERFLOW)?;
+    result.st_atime = x
+        .stx_atime
+        .tv_sec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_atime_nsec = x.stx_atime.tv_nsec as _;
+    result.st_mtime = x
+        .stx_mtime
+        .tv_sec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_mtime_nsec = x.stx_mtime.tv_nsec as _;
+    result.st_ctime = x
+        .stx_ctime
+        .tv_sec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_ctime_nsec = x.stx_ctime.tv_nsec as _;
+    result.st_ino = x.stx_ino.into();
+
+    Ok(result)
+}
+
+/// Convert from a Linux `stat64` value to rustix's `Stat`.
+#[cfg(all(linux_kernel, target_pointer_width = "32"))]
+fn stat64_to_stat(s64: c::stat64) -> io::Result<Stat> {
+    Ok(Stat {
+        st_dev: s64.st_dev.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_mode: s64.st_mode.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_nlink: s64.st_nlink.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_uid: s64.st_uid.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_gid: s64.st_gid.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_rdev: s64.st_rdev.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_size: s64.st_size.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_blksize: s64.st_blksize.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_blocks: s64.st_blocks.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_atime: s64.st_atime.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_atime_nsec: s64
+            .st_atime_nsec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_mtime: s64.st_mtime.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_mtime_nsec: s64
+            .st_mtime_nsec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_ctime: s64.st_ctime.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        st_ctime_nsec: s64
+            .st_ctime_nsec
+            .try_into()
+            .map_err(|_| io::Errno::OVERFLOW)?,
+        st_ino: s64.st_ino.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+    })
+}
+
+/// Convert from a Linux `stat64` value to rustix's `Stat`.
+///
+/// mips64' `struct stat64` in libc has private fields, and `st_blocks` has
+/// type `i64`.
+#[cfg(all(linux_kernel, any(target_arch = "mips64", target_arch = "mips64r6")))]
+fn stat64_to_stat(s64: c::stat64) -> io::Result<Stat> {
+    let mut result: Stat = unsafe { core::mem::zeroed() };
+
+    result.st_dev = s64.st_dev.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_mode = s64.st_mode.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_nlink = s64.st_nlink.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_uid = s64.st_uid.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_gid = s64.st_gid.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_rdev = s64.st_rdev.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_size = s64.st_size.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_blksize = s64.st_blksize.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_blocks = s64.st_blocks.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_atime = s64.st_atime.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_atime_nsec = s64
+        .st_atime_nsec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_mtime = s64.st_mtime.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_mtime_nsec = s64
+        .st_mtime_nsec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_ctime = s64.st_ctime.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_ctime_nsec = s64
+        .st_ctime_nsec
+        .try_into()
+        .map_err(|_| io::Errno::OVERFLOW)?;
+    result.st_ino = s64.st_ino.try_into().map_err(|_| io::Errno::OVERFLOW)?;
+
+    Ok(result)
+}
+
+#[cfg(linux_kernel)]
+#[allow(non_upper_case_globals)]
+mod sys {
+    use super::{c, BorrowedFd, Statx};
+
+    weak_or_syscall! {
+        pub(super) fn statx(
+            dirfd_: BorrowedFd<'_>,
+            path: *const c::c_char,
+            flags: c::c_int,
+            mask: c::c_uint,
+            buf: *mut Statx
+        ) via SYS_statx -> c::c_int
+    }
+}
+
+#[cfg(linux_kernel)]
+#[allow(non_upper_case_globals)]
+pub(crate) fn statx(
+    dirfd: BorrowedFd<'_>,
+    path: &CStr,
+    flags: AtFlags,
+    mask: StatxFlags,
+) -> io::Result<Statx> {
+    // If a future Linux kernel adds more fields to `struct statx` and users
+    // passing flags unknown to rustix in `StatxFlags`, we could end up
+    // writing outside of the buffer. To prevent this possibility, we mask off
+    // any flags that we don't know about.
+    //
+    // This includes `STATX__RESERVED`, which has a value that we know, but
+    // which could take on arbitrary new meaning in the future. Linux currently
+    // rejects this flag with `EINVAL`, so we do the same.
+    //
+    // This doesn't rely on `STATX_ALL` because [it's deprecated] and already
+    // doesn't represent all the known flags.
+    //
+    // [it's deprecated]: https://patchwork.kernel.org/project/linux-fsdevel/patch/20200505095915.11275-7-mszeredi@redhat.com/
+    #[cfg(not(any(target_os = "android", target_env = "musl")))]
+    const STATX__RESERVED: u32 = c::STATX__RESERVED as u32;
+    #[cfg(any(target_os = "android", target_env = "musl"))]
+    const STATX__RESERVED: u32 = linux_raw_sys::general::STATX__RESERVED;
+    if (mask.bits() & STATX__RESERVED) == STATX__RESERVED {
+        return Err(io::Errno::INVAL);
+    }
+    let mask = mask & StatxFlags::all();
+
+    let mut statx_buf = MaybeUninit::<Statx>::uninit();
+    unsafe {
+        ret(sys::statx(
+            dirfd,
+            c_str(path),
+            bitflags_bits!(flags),
+            mask.bits(),
+            statx_buf.as_mut_ptr(),
+        ))?;
+        Ok(statx_buf.assume_init())
+    }
+}
+
+#[cfg(linux_kernel)]
+#[inline]
+pub(crate) fn is_statx_available() -> bool {
+    unsafe {
+        // Call `statx` with null pointers so that if it fails for any reason
+        // other than `EFAULT`, we know it's not supported.
+        matches!(
+            ret(sys::statx(CWD, null(), 0, 0, null_mut())),
+            Err(io::Errno::FAULT)
+        )
+    }
+}
+
+#[cfg(apple)]
+pub(crate) unsafe fn fcopyfile(
+    from: BorrowedFd<'_>,
+    to: BorrowedFd<'_>,
+    state: copyfile_state_t,
+    flags: CopyfileFlags,
+) -> io::Result<()> {
+    extern "C" {
+        fn fcopyfile(
+            from: c::c_int,
+            to: c::c_int,
+            state: copyfile_state_t,
+            flags: c::c_uint,
+        ) -> c::c_int;
+    }
+
+    nonnegative_ret(fcopyfile(
+        borrowed_fd(from),
+        borrowed_fd(to),
+        state,
+        bitflags_bits!(flags),
+    ))
+}
+
+#[cfg(apple)]
+pub(crate) fn copyfile_state_alloc() -> io::Result<copyfile_state_t> {
+    extern "C" {
+        fn copyfile_state_alloc() -> copyfile_state_t;
+    }
+
+    let result = unsafe { copyfile_state_alloc() };
+    if result.0.is_null() {
+        Err(io::Errno::last_os_error())
+    } else {
+        Ok(result)
+    }
+}
+
+#[cfg(apple)]
+pub(crate) unsafe fn copyfile_state_free(state: copyfile_state_t) -> io::Result<()> {
+    extern "C" {
+        fn copyfile_state_free(state: copyfile_state_t) -> c::c_int;
+    }
+
+    nonnegative_ret(copyfile_state_free(state))
+}
+
+#[cfg(apple)]
+const COPYFILE_STATE_COPIED: u32 = 8;
+
+#[cfg(apple)]
+pub(crate) unsafe fn copyfile_state_get_copied(state: copyfile_state_t) -> io::Result<u64> {
+    let mut copied = MaybeUninit::<u64>::uninit();
+    copyfile_state_get(state, COPYFILE_STATE_COPIED, copied.as_mut_ptr().cast())?;
+    Ok(copied.assume_init())
+}
+
+#[cfg(apple)]
+pub(crate) unsafe fn copyfile_state_get(
+    state: copyfile_state_t,
+    flag: u32,
+    dst: *mut c::c_void,
+) -> io::Result<()> {
+    extern "C" {
+        fn copyfile_state_get(state: copyfile_state_t, flag: u32, dst: *mut c::c_void) -> c::c_int;
+    }
+
+    nonnegative_ret(copyfile_state_get(state, flag, dst))
+}
+
+#[cfg(all(apple, feature = "alloc"))]
+pub(crate) fn getpath(fd: BorrowedFd<'_>) -> io::Result<CString> {
+    // The use of `PATH_MAX` is generally not encouraged, but it
+    // is inevitable in this case because macOS defines `fcntl` with
+    // `F_GETPATH` in terms of `MAXPATHLEN`, and there are no
+    // alternatives. If a better method is invented, it should be used
+    // instead.
+    let mut buf = vec![0; c::PATH_MAX as usize];
+
+    // From the [macOS `fcntl` manual page]:
+    // `F_GETPATH` - Get the path of the file descriptor `Fildes`. The argument
+    //               must be a buffer of size `MAXPATHLEN` or greater.
+    //
+    // [macOS `fcntl` manual page]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fcntl.2.html
+    unsafe {
+        ret(c::fcntl(borrowed_fd(fd), c::F_GETPATH, buf.as_mut_ptr()))?;
+    }
+
+    let l = buf.iter().position(|&c| c == 0).unwrap();
+    buf.truncate(l);
+    buf.shrink_to_fit();
+
+    Ok(CString::new(buf).unwrap())
+}
+
+#[cfg(apple)]
+pub(crate) fn fcntl_rdadvise(fd: BorrowedFd<'_>, offset: u64, len: u64) -> io::Result<()> {
+    // From the [macOS `fcntl` manual page]:
+    // `F_RDADVISE` - Issue an advisory read async with no copy to user.
+    //
+    // The `F_RDADVISE` command operates on the following structure which holds
+    // information passed from the user to the system:
+    //
+    // ```c
+    // struct radvisory {
+    //      off_t   ra_offset;  /* offset into the file */
+    //      int     ra_count;   /* size of the read     */
+    // };
+    // ```
+    //
+    // [macOS `fcntl` manual page]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fcntl.2.html
+    let ra_offset = match offset.try_into() {
+        Ok(len) => len,
+        // If this conversion fails, the user is providing an offset outside
+        // any possible file extent, so just ignore it.
+        Err(_) => return Ok(()),
+    };
+    let ra_count = match len.try_into() {
+        Ok(len) => len,
+        // If this conversion fails, the user is providing a dubiously large
+        // hint which is unlikely to improve performance.
+        Err(_) => return Ok(()),
+    };
+    unsafe {
+        let radvisory = c::radvisory {
+            ra_offset,
+            ra_count,
+        };
+        ret(c::fcntl(borrowed_fd(fd), c::F_RDADVISE, &radvisory))
+    }
+}
+
+#[cfg(apple)]
+pub(crate) fn fcntl_fullfsync(fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_FULLFSYNC)) }
+}
+
+#[cfg(apple)]
+pub(crate) fn fcntl_nocache(fd: BorrowedFd<'_>, value: bool) -> io::Result<()> {
+    unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_NOCACHE, value as c::c_int)) }
+}
+
+#[cfg(apple)]
+pub(crate) fn fcntl_global_nocache(fd: BorrowedFd<'_>, value: bool) -> io::Result<()> {
+    unsafe {
+        ret(c::fcntl(
+            borrowed_fd(fd),
+            c::F_GLOBAL_NOCACHE,
+            value as c::c_int,
+        ))
+    }
+}
+
+/// Convert `times` from a `futimens`/`utimensat` argument into `setattrlist`
+/// arguments.
+#[cfg(apple)]
+fn times_to_attrlist(times: &Timestamps) -> (c::size_t, [c::timespec; 2], Attrlist) {
+    // ABI details.
+    const ATTR_CMN_MODTIME: u32 = 0x0000_0400;
+    const ATTR_CMN_ACCTIME: u32 = 0x0000_1000;
+    const ATTR_BIT_MAP_COUNT: u16 = 5;
+
+    let mut times = times.clone();
+
+    // If we have any `UTIME_NOW` elements, replace them with the current time.
+    if times.last_access.tv_nsec == c::UTIME_NOW || times.last_modification.tv_nsec == c::UTIME_NOW
+    {
+        let now = {
+            let mut tv = c::timeval {
+                tv_sec: 0,
+                tv_usec: 0,
+            };
+            unsafe {
+                let r = c::gettimeofday(&mut tv, null_mut());
+                assert_eq!(r, 0);
+            }
+            c::timespec {
+                tv_sec: tv.tv_sec,
+                tv_nsec: (tv.tv_usec * 1000) as _,
+            }
+        };
+        if times.last_access.tv_nsec == c::UTIME_NOW {
+            times.last_access = now;
+        }
+        if times.last_modification.tv_nsec == c::UTIME_NOW {
+            times.last_modification = now;
+        }
+    }
+
+    // Pack the return values following the rules for [`getattrlist`].
+    //
+    // [`getattrlist`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getattrlist.2.html
+    let mut times_size = 0;
+    let mut attrs = Attrlist {
+        bitmapcount: ATTR_BIT_MAP_COUNT,
+        reserved: 0,
+        commonattr: 0,
+        volattr: 0,
+        dirattr: 0,
+        fileattr: 0,
+        forkattr: 0,
+    };
+    let mut return_times = [c::timespec {
+        tv_sec: 0,
+        tv_nsec: 0,
+    }; 2];
+    let mut times_index = 0;
+    if times.last_modification.tv_nsec != c::UTIME_OMIT {
+        attrs.commonattr |= ATTR_CMN_MODTIME;
+        return_times[times_index] = times.last_modification;
+        times_index += 1;
+        times_size += size_of::<c::timespec>();
+    }
+    if times.last_access.tv_nsec != c::UTIME_OMIT {
+        attrs.commonattr |= ATTR_CMN_ACCTIME;
+        return_times[times_index] = times.last_access;
+        times_size += size_of::<c::timespec>();
+    }
+
+    (times_size, return_times, attrs)
+}
+
+/// Support type for `Attrlist`.
+#[cfg(apple)]
+type Attrgroup = u32;
+
+/// Attribute list for use with `setattrlist`.
+#[cfg(apple)]
+#[repr(C)]
+struct Attrlist {
+    bitmapcount: u16,
+    reserved: u16,
+    commonattr: Attrgroup,
+    volattr: Attrgroup,
+    dirattr: Attrgroup,
+    fileattr: Attrgroup,
+    forkattr: Attrgroup,
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn getxattr(path: &CStr, name: &CStr, value: &mut [u8]) -> io::Result<usize> {
+    let value_ptr = value.as_mut_ptr();
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::getxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::getxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+            0,
+            0,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn lgetxattr(path: &CStr, name: &CStr, value: &mut [u8]) -> io::Result<usize> {
+    let value_ptr = value.as_mut_ptr();
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::lgetxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::getxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+            0,
+            c::XATTR_NOFOLLOW,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn fgetxattr(fd: BorrowedFd<'_>, name: &CStr, value: &mut [u8]) -> io::Result<usize> {
+    let value_ptr = value.as_mut_ptr();
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::fgetxattr(
+            borrowed_fd(fd),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::fgetxattr(
+            borrowed_fd(fd),
+            name.as_ptr(),
+            value_ptr.cast::<c::c_void>(),
+            value.len(),
+            0,
+            0,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn setxattr(
+    path: &CStr,
+    name: &CStr,
+    value: &[u8],
+    flags: XattrFlags,
+) -> io::Result<()> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::setxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            flags.bits() as i32,
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::setxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            0,
+            flags.bits() as i32,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn lsetxattr(
+    path: &CStr,
+    name: &CStr,
+    value: &[u8],
+    flags: XattrFlags,
+) -> io::Result<()> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::lsetxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            flags.bits() as i32,
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::setxattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            0,
+            flags.bits() as i32 | c::XATTR_NOFOLLOW,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn fsetxattr(
+    fd: BorrowedFd<'_>,
+    name: &CStr,
+    value: &[u8],
+    flags: XattrFlags,
+) -> io::Result<()> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::fsetxattr(
+            borrowed_fd(fd),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            flags.bits() as i32,
+        ))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::fsetxattr(
+            borrowed_fd(fd),
+            name.as_ptr(),
+            value.as_ptr().cast::<c::c_void>(),
+            value.len(),
+            0,
+            flags.bits() as i32,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn listxattr(path: &CStr, list: &mut [c::c_char]) -> io::Result<usize> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::listxattr(path.as_ptr(), list.as_mut_ptr(), list.len()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::listxattr(
+            path.as_ptr(),
+            list.as_mut_ptr(),
+            list.len(),
+            0,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn llistxattr(path: &CStr, list: &mut [c::c_char]) -> io::Result<usize> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::llistxattr(path.as_ptr(), list.as_mut_ptr(), list.len()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::listxattr(
+            path.as_ptr(),
+            list.as_mut_ptr(),
+            list.len(),
+            c::XATTR_NOFOLLOW,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn flistxattr(fd: BorrowedFd<'_>, list: &mut [c::c_char]) -> io::Result<usize> {
+    let fd = borrowed_fd(fd);
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret_usize(c::flistxattr(fd, list.as_mut_ptr(), list.len()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret_usize(c::flistxattr(fd, list.as_mut_ptr(), list.len(), 0))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn removexattr(path: &CStr, name: &CStr) -> io::Result<()> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::removexattr(path.as_ptr(), name.as_ptr()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::removexattr(path.as_ptr(), name.as_ptr(), 0))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn lremovexattr(path: &CStr, name: &CStr) -> io::Result<()> {
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::lremovexattr(path.as_ptr(), name.as_ptr()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::removexattr(
+            path.as_ptr(),
+            name.as_ptr(),
+            c::XATTR_NOFOLLOW,
+        ))
+    }
+}
+
+#[cfg(any(apple, linux_kernel))]
+pub(crate) fn fremovexattr(fd: BorrowedFd<'_>, name: &CStr) -> io::Result<()> {
+    let fd = borrowed_fd(fd);
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::fremovexattr(fd, name.as_ptr()))
+    }
+
+    #[cfg(apple)]
+    unsafe {
+        ret(c::fremovexattr(fd, name.as_ptr(), 0))
+    }
+}
+
+#[test]
+fn test_sizes() {
+    #[cfg(linux_kernel)]
+    assert_eq_size!(c::loff_t, u64);
+
+    // Assert that `Timestamps` has the expected layout. If we're not fixing
+    // y2038, libc's type should match ours. If we are, it's smaller.
+    #[cfg(not(fix_y2038))]
+    assert_eq_size!([c::timespec; 2], Timestamps);
+    #[cfg(fix_y2038)]
+    assert!(core::mem::size_of::<[c::timespec; 2]>() < core::mem::size_of::<Timestamps>());
+}