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std::unix::fs: copy simplification for apple.

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since we do support from macOs Sierra, we avoid the little runtime overhead
with the fclonefileat symbol check.
This commit is contained in:
David Carlier 2024-06-21 21:13:14 +01:00
parent 5ced3dad57
commit 65530ba100
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1 changed files with 15 additions and 35 deletions
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50
library/std/src/sys/pal/unix/fs.rs
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@ -20,14 +20,14 @@
use crate::sys::{cvt, cvt_r};
use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
#[cfg(any(all(target_os = "linux", target_env = "gnu"), target_vendor = "apple"))]
#[cfg(all(target_os = "linux", target_env = "gnu"))]
use crate::sys::weak::syscall;
#[cfg(target_os = "android")]
use crate::sys::weak::weak;
use libc::{c_int, mode_t};
#[cfg(any(all(target_os = "linux", target_env = "gnu"), target_vendor = "apple"))]
#[cfg(all(target_os = "linux", target_env = "gnu"))]
use libc::c_char;
#[cfg(any(
all(target_os = "linux", not(target_env = "musl")),
@ -1891,8 +1891,6 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
#[cfg(target_vendor = "apple")]
pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
use crate::sync::atomic::{AtomicBool, Ordering};
const COPYFILE_ALL: libc::copyfile_flags_t = libc::COPYFILE_METADATA | libc::COPYFILE_DATA;
struct FreeOnDrop(libc::copyfile_state_t);
@ -1907,39 +1905,21 @@ fn drop(&mut self) {
}
}
// MacOS prior to 10.12 don't support `fclonefileat`
// We store the availability in a global to avoid unnecessary syscalls
static HAS_FCLONEFILEAT: AtomicBool = AtomicBool::new(true);
syscall! {
// Mirrors `libc::fclonefileat`
fn fclonefileat(
srcfd: libc::c_int,
dst_dirfd: libc::c_int,
dst: *const c_char,
flags: libc::c_int
) -> libc::c_int
}
let (reader, reader_metadata) = open_from(from)?;
// Opportunistically attempt to create a copy-on-write clone of `from`
// using `fclonefileat`.
if HAS_FCLONEFILEAT.load(Ordering::Relaxed) {
let clonefile_result = run_path_with_cstr(to, &|to| {
cvt(unsafe { fclonefileat(reader.as_raw_fd(), libc::AT_FDCWD, to.as_ptr(), 0) })
});
match clonefile_result {
Ok(_) => return Ok(reader_metadata.len()),
Err(err) => match err.raw_os_error() {
// `fclonefileat` will fail on non-APFS volumes, if the
// destination already exists, or if the source and destination
// are on different devices. In all these cases `fcopyfile`
// should succeed.
Some(libc::ENOTSUP) | Some(libc::EEXIST) | Some(libc::EXDEV) => (),
Some(libc::ENOSYS) => HAS_FCLONEFILEAT.store(false, Ordering::Relaxed),
_ => return Err(err),
},
}
let clonefile_result = run_path_with_cstr(to, &|to| {
cvt(unsafe { libc::fclonefileat(reader.as_raw_fd(), libc::AT_FDCWD, to.as_ptr(), 0) })
});
match clonefile_result {
Ok(_) => return Ok(reader_metadata.len()),
Err(e) => match e.raw_os_error() {
// `fclonefileat` will fail on non-APFS volumes, if the
// destination already exists, or if the source and destination
// are on different devices. In all these cases `fcopyfile`
// should succeed.
Some(libc::ENOTSUP) | Some(libc::EEXIST) | Some(libc::EXDEV) => (),
_ => return Err(e),
},
}
// Fall back to using `fcopyfile` if `fclonefileat` does not succeed.