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

since we do support from macOs Sierra, we avoid the little runtime overhead with the fclonefileat symbol check.
rust-lang · Jun 21, 2024 · 65530ba · 65530ba
1 parent 5ced3da
commit 65530ba
Showing 1 changed file with 15 additions and 35 deletions.
diff --git a/library/std/src/sys/pal/unix/fs.rs b/library/std/src/sys/pal/unix/fs.rs
@@ -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")),
@@ -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 @@ 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.