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std::unix::fs: copy simplification for apple. #126807

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Merged
merged 1 commit into from
Jun 24, 2024
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std::unix::fs: copy simplification for apple. #126807

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50 changes: 15 additions & 35 deletions library/std/src/sys/pal/unix/fs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,14 +20,14 @@ use crate::sys::time::SystemTime;
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")),
Expand Down Expand Up @@ -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);
Expand All @@ -1907,39 +1905,21 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
}
}

// 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.
Expand Down