monmohan / xferspdy

Xferspdy provides binary diff and patch library in golang. [Mentioned in Awesome Go, https://github.com/avelino/awesome-go]

xferspdy

This library provides binary diff and patch API in golang.

Supported today:

• Command line utilities to diff and patch binary files
• Library for fingerprint generation, rolling hash and block matching
• NEW : For large files, fingerprint generation automatically switches to parallel mode wherein multiple go routines are used concurrently. For files > 20 MB, there is an improvement of ~50% compared to sequential fingerprint generation.

Reference : [Rsync Algorithm] (https://rsync.samba.org/tech_report/node2.html)

Setup

• Need to have go installed, [golang downloads] (https://golang.org/dl/)

• Do go get

   `go get github.com/monmohan/xferspdy`
  

• Install the command line utilities

  Run go install ./... from the xferspdy directory

Using the API

See GoDoc. The docs also contain an example usage of the API.

Using the fpgen, diff and patch CLI utilities:

The library also provides CLI wrappers on API.

Example

• You can see the usage of any of these commands using $ GOPATH/bin/<command> --help

• Lets say you have a binary file (e.g. power point presentation MyPrezVersion1.pptx).

• First generate a fingerprint of version 1

  $ GOPATH/bin/fpgen -file <path>/MyPrezVersion1.pptx

  This will generate the fingerprint file /MyPrezVersion1.pptx.fingerprint.

• Lets say that the file was changed now (for example add a slide or image) and saved as MyPrezVersion2.pptx

• Now Generate a diff (doesn't require original file)

  $ GOPATH/bin/diff -fingerprint <path>/MyPrezVersion1.pptx.fingerprint -file <path>/MyPrezVersion2.pptx

It will create a patch file <path>/MyPrezVersion2.pptx.patch

• Now patch the Version 1 file to get the Version 2

  $ GOPATH/bin/patch -patch <path>/MyPrezVersion2.pptx.patch -base <path>/MyPrezVersion1.pptx

• This will generate /Patched_MyPrezVersion1.pptx. This file would exactly be same as MyPrezVersion2.pptx.

NOTE: diff and patch are also common utilities present on most distributions so its better to give explicit path to these binaries. for example use $GOPATH/bin/diff and $GOPATH/bin/patch