This package provides both a command-line utility and a Go library for computing Open Subtitles-format hashes for files and arbitrary data.
The Open Subtitles hash is an 8-byte identifying value produced from the input data's size and from 64 kibibytes (65536 bytes) at the beginning and end of the data, and made by simply interpreting chunks of it (which may overlap) as integers and summing them. It goes without saying that this is not a substitute for a SHA256 or Keccak hash of the full data. Instead it's a very compact and very cheap-to-produce identifier useful for fast deduplication and match-narrowing.
-x: show hexadecimal values (default).-b: show binary values.-d: show decimal values (64-bit integers).-f: show filename with output.-pipe: read lines from stdin and write results to stdout.-sep: specify string to use to separate fields in tabular output (default: tab).
> oshash parrots.jpg
f44f78d5e4a8fbee
> oshash -d parrots.jpg
17604422328474205166
> cat filesnames.txt | oshash -pipe
f44f78d5e4a8fbee
bf01ea2bi00a21f7
a189811aabf1ce20
> cat filesnames.txt | oshash -pipe -f -x -d
images/parrot.jpg f44f78d5e4a8fbee 17604422328474205166
images/toucan.jpg bf01ea2bi00a21f7 10242892102200212726
images/lorikeet.jpg a189811aabf1ce20 18827272012277274944
> oshash -f -sep "," "parrot.jpg" "toucan.jpg"
parrot.jpg,f44f78d5e4a8fbee
toucan.jpg,bf01ea2bi00a21f7
oshash.FromFile(*os.File) (uint64, err)oshash.FromFilepath(string) (uint64, err)oshash.FromBytes([]byte) (uint64, err)
To convert the uint64 values to a hexdecimal string, use strconv.FormatUint(oshash_value, 16).
Test-suite parrot image by edmondlafoto.
©️ 2020 Ryan Plant
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.