Go reflink library

Package reflink provides a simple library allowing to create reflinks (shallow copies) of files enabling copy-on-write behavior.

This library currently only supports creating reflinks on Linux and requires a compatible filesystem (e.g. btrfs)

A small command line utility is also provided.

Installation

Install using go get:

go get github.com/morelj/reflink

Usage

Use the Clone function to create a reflink:

import "reflink"

func main() {
	// Clone /source to /target
	err := reflink.Clone("/source", "/target", 0, 0644)
	if err != nil {
		panic(err)
	}

	// Clone /source to /target2, preserving source mode & owner if possible
	err = Clone("/source", "/target2", reflink.PreserveMode|reflink.PreserveOwner|reflink.FailSafe, 0644)
	if err != nil {
		panic(err)
	}
}

You may also only clone a subset of a file using CloneRange:

import "reflink"

func main() {
	// Clone the first 512 bytes of /source to /target
	err := reflink.CloneRange("/source", "/target", 0, 0644, reflink.Offsets{
		SrcOffset:  0,
		SrcLength:  512,
		DestOffset: 0,
	})
	if err != nil {
		panic(err)
	}
}

On unsupported operating systems, Clone and CloneRange always return reflink.ErrUnsupported.