fabric-loom/src/main/java/net/fabricmc/loom/util/Checksum.java

/*
 * This file is part of fabric-loom, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2016, 2017, 2018 FabricMC
 *
 * 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.
 */

package net.fabricmc.loom.util;

import com.google.common.hash.HashCode;
import com.google.common.hash.Hashing;
import com.google.common.io.Files;

import java.io.File;
import java.io.IOException;

public class Checksum {
	public static boolean equals(File file, String checksum) {
		if (file == null) {
			return false;
		}
		try {
			//noinspection deprecation
			HashCode hash = Files.asByteSource(file).hash(Hashing.sha1());
			StringBuilder builder = new StringBuilder();
			for (Byte hashBytes : hash.asBytes()) {
				builder.append(Integer.toString((hashBytes & 0xFF) + 0x100, 16).substring(1));
			}
			return builder.toString().equals(checksum);
		} catch (IOException e) {
			e.printStackTrace();
		}
		return false;
	}
}