Function reflink

pub fn reflink(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()>

Copies a file using COW semantics.

For compatibility reasons with macOS, the target file will be created using OpenOptions::create_new. If you want to overwrite existing files, make sure you manually delete the target file first if it exists.

match reflink_copy::reflink("src.txt", "dest.txt") {
    Ok(()) => println!("file has been reflinked"),
    Err(e) => println!("error while reflinking: {:?}", e)
}

Implementation details per platform

Linux / Android

Uses ioctl_ficlone. Supported file systems include btrfs and XFS (and maybe more in the future). NOTE that it generates a temporary file and is not atomic.

MacOS / OS X / iOS

Uses clonefile library function. This is supported on OS X Version >=10.12 and iOS version >= 10.0 This will work on APFS partitions (which means most desktop systems are capable). If src names a directory, the directory hierarchy is cloned as if each item was cloned individually.

Windows

Uses ioctl FSCTL_DUPLICATE_EXTENTS_TO_FILE.

Supports ReFS on Windows Server and Windows Dev Drives. Important note: The windows implementation is currently untested and probably buggy. Contributions/testers with access to a Windows Server or Dev Drives are welcome. More Information on Dev Drives

NOTE that it generates a temporary file and is not atomic.