Add a license checker script

package.json

@@ -157,6 +157,7 @@
 		"build:packages": "cross-env EXCLUDE_PACKAGES=babel-plugin-import-jsx-pragma,jest-console,postcss-themes node ./bin/packages/build.js",
 		"build": "npm run build:packages && cross-env NODE_ENV=production webpack",
 		"check-engines": "check-node-version --package",
+		"check-licenses": "concurrently \"wp-scripts check-licenses --prod --gpl2\" \"wp-scripts check-licenses --dev\"",
 		"ci": "concurrently \"npm run lint\" \"npm run test-unit:coverage-ci\"",
 		"predev": "npm run check-engines",
 		"dev": "npm run build:packages && concurrently \"cross-env webpack --watch\" \"npm run dev:packages\"",
@@ -174,7 +175,7 @@
 		"lint-css": "stylelint '**/*.scss'",
 		"lint-css:fix": "stylelint '**/*.scss' --fix",
 		"package-plugin": "./bin/build-plugin-zip.sh",
-		"postinstall": "npm run build:packages",
+		"postinstall": "npm run check-licenses && npm run build:packages",
 		"pot-to-php": "./bin/pot-to-php.js",
 		"precommit": "lint-staged",
 		"publish:check": "npm run build:packages && lerna updated",

packages/scripts/package.json

@@ -34,6 +34,7 @@
 		"@wordpress/babel-preset-default": "file:../babel-preset-default",
 		"@wordpress/jest-preset-default": "file:../jest-preset-default",
 		"@wordpress/npm-package-json-lint-config": "file:../npm-package-json-lint-config",
+		"chalk": "^2.4.1",
 		"cross-spawn": "^5.1.0",
 		"jest": "^23.4.2",
 		"npm-package-json-lint": "^3.3.0",

packages/scripts/scripts/check-licenses.js

@@ -0,0 +1,170 @@
+/**
+ * External dependencies
+ */
+const spawn = require( 'cross-spawn' );
+const { existsSync, readFileSync } = require( 'fs' );
+const chalk = require( 'chalk' );
+
+/**
+ * Internal dependencies
+ */
+const { hasCliArg } = require( '../utils' );
+
+const ERROR = chalk.reset.inverse.bold.red( ' ERROR ' );
+
+const prod = hasCliArg( '--prod' ) || hasCliArg( '--production' );
+const dev = hasCliArg( '--dev' ) || hasCliArg( '--development' );
+const gpl2 = hasCliArg( '--gpl2' );
+
+const gpl2Licenses = [
+	'Apache-2.0 WITH LLVM-exception',
+	'Artistic-2.0',
+	'BSD',
+	'BSD-2-Clause',
+	'BSD-3-Clause',
+	'BSD-like',
+	'CC-BY-3.0',
+	'CC-BY-4.0',
+	'CC0-1.0',
+	'GPL-2.0',
+	'GPL-2.0+',
+	'GPL-2.0-or-later',
+	'ISC',
+	'LGPL-2.1',
+	'MIT',
+	'MIT/X11',
+	'MIT (http://mootools.net/license.txt)',
+	'MPL-2.0',
+	'Public Domain',
+	'Unlicense',
+	'WTFPL',
+	'Zlib',
+	'(MIT AND BSD-3-Clause)',
+	'(MIT AND Zlib)',
+];
+
+const ossLicenses = [
+	'Apache-2.0',
+	'Apache 2.0',
+	'Apache License, Version 2.0',
+	'Apache version 2.0',
+];
+
+const licenses = [
+	...gpl2Licenses,
+	...( gpl2 ? [] : ossLicenses ),
+];
+
+const licenseFiles = [
+	'LICENCE',
+	'license',
+	'LICENSE',
+	'LICENSE.md',
+	'LICENSE.txt',
+	'LICENSE-MIT',
+	'MIT-LICENSE.txt',
+	'Readme.md',
+	'README.md',
+];
+
+const licenseFileStrings = {
+	'Apache-2.0': [
+		'Licensed under the Apache License, Version 2.0',
+	],
+	BSD: [
+		'Redistributions in binary form must reproduce the above copyright notice,',
+	],
+	MIT: [
+		'Permission is hereby granted, free of charge,',
+		'## License\n\nMIT',
+		'## License\n\n  MIT',
+	],
+};
+
+const checkLicense = ( allowedLicense, licenseType ) => {
+	if ( ! licenseType ) {
+		return false;
+	}
+
+	const formattedAllowedLicense = allowedLicense.toLowerCase();
+	const formattedlicenseType = licenseType.toLowerCase();
+
+	if ( formattedAllowedLicense === formattedlicenseType ) {
+		return true;
+	}
+
+	if ( licenseType.indexOf( 'OR' ) < 0 ) {
+		return false;
+	}
+
+	const subLicenseTypes = formattedlicenseType.replace( /^\(*/g, '' ).replace( /\)*$/, '' ).split( ' or ' ).map( ( e ) => e.trim() );
+
+	return subLicenseTypes.reduce( ( satisfied, subLicenseType ) => {
+		if ( checkLicense( allowedLicense, subLicenseType ) ) {
+			return true;
+		}
+		return satisfied;
+	}, false );
+};
+
+const child = spawn.sync( 'npm', [
+	'ls',
+	'--parseable',
+	...( prod ? [ '--prod' ] : [] ),
+	...( dev ? [ '--dev' ] : [] ),
+] );
+
+const modules = child.stdout.toString().split( '\n' );
+
+modules.forEach( ( path ) => {
+	if ( ! path ) {
+		return;
+	}
+
+	const filename = path + '/package.json';
+	if ( ! existsSync( filename ) ) {
+		process.stdout.write( `Unable to locate package.json in ${ path }.` );
+		process.exit( 1 );
+	}
+
+	const packageInfo = require( filename );
+	const license = packageInfo.license || ( packageInfo.licenses && packageInfo.licenses.map( ( l ) => l.type || l ).join( ' OR ' ) );
+	let licenseType = typeof license === 'object' ? license.type : license;
+
+	if ( licenseType === undefined ) {
+		licenseType = licenseFiles.reduce( ( detectedType, licenseFile ) => {
+			if ( detectedType ) {
+				return detectedType;
+			}
+
+			const licensePath = path + '/' + licenseFile;
+
+			if ( existsSync( licensePath ) ) {
+				const licenseText = readFileSync( licensePath ).toString();
+
+				return Object.keys( licenseFileStrings ).reduce( ( stringDetectedType, licenseStringType ) => {
+					const licenseFileString = licenseFileStrings[ licenseStringType ];
+
+					return licenseFileString.reduce( ( currentDetectedType, fileString ) => {
+						if ( licenseText.includes( fileString ) ) {
+							return licenseStringType;
+						}
+						return currentDetectedType;
+					}, stringDetectedType );
+				}, detectedType );
+			}
+		}, false );
+	}
+
+	const allowed = licenses.reduce( ( satisfied, allowedLicense ) => {
+		if ( checkLicense( allowedLicense, licenseType ) ) {
+			return true;
+		}
+		return satisfied;
+	}, false );
+
+	if ( ! allowed ) {
+		process.exitCode = 1;
+		process.stdout.write( `${ ERROR } Module ${ packageInfo.name } has an incompatible license '${ licenseType }'.\n` );
+	}
+} );