License Classifier
Introduction
The license classifier is a library and set of tools that can analyze text to
determine what type of license it contains. It searches for license texts in a
file and compares them to an archive of known licenses. These files could be,
e.g., LICENSE files with a single or multiple licenses in it, or source code
files with the license text in a comment.
A "confidence level" is associated with each result indicating how close the
match was. A confidence level of 1.0 indicates an exact match, while a
confidence level of 0.0 indicates that no license was able to match the text.
Adding a new license
Adding a new license is straight-forward:
-
Create a file in
licenses/.- The filename should be the name of the license or its abbreviation. If
the license is an Open Source license, use the appropriate identifier
specified at https://spdx.org/licenses/. - If the license is the "header" version of the license, append the suffix
".header" to it. Seelicenses/README.mdfor more details.
- The filename should be the name of the license or its abbreviation. If
-
Add the license name to the list in
license_type.go. -
Regenerate the
licenses.dbfile by running the license serializer:$ license_serializer -output licenseclassifier/licenses -
Create and run appropriate tests to verify that the license is indeed
present.
Tools
Identify license
identify_license is a command line tool that can identify the license(s)
within a file.
$ identify_license LICENSE
LICENSE: GPL-2.0 (confidence: 1, offset: 0, extent: 14794)
LICENSE: LGPL-2.1 (confidence: 1, offset: 18366, extent: 23829)
LICENSE: MIT (confidence: 1, offset: 17255, extent: 1059)
License serializer
The license_serializer tool regenerates the licenses.db archive. The archive
contains preprocessed license texts for quicker comparisons against unknown
texts.
$ license_serializer -output licenseclassifier/licenses
This is not an official Google product (experimental or otherwise), it is just
code that happens to be owned by Google.