net.minecraftforge.gradle.common.util.HashFunction Maven / Gradle / Ivy

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Minecraft mod development framework used by Forge and FML for the gradle build system adapted for mohist api.
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/*
 * ForgeGradle
 * Copyright (C) 2018 Forge Development LLC
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

package net.minecraftforge.gradle.common.util;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Locale;

import org.apache.commons.io.IOUtils;

import javax.annotation.Nullable;

/**
 * Different hash functions.
 *
 * All of these hashing functions are standardized, and is required to be implemented by all JREs. However, {@link
 * MessageDigest#getInstance(String)} declares as throwing the checked exception of {@link NoSuchAlgorithmException}.
 *
 * This class offers a cleaner method to retrieve an instance of these hashing functions, without having to wrap in a
 * {@code try}-{@code catch} block.
 */
public enum HashFunction {
    MD5("md5", 32),
    SHA1("SHA-1", 40),
    SHA256("SHA-256", 64),
    SHA512("SHA-512", 128);

    private final String algo;
    private final String pad;

    HashFunction(String algo, int length) {
        this.algo = algo;
        this.pad = String.format(Locale.ROOT, "%0" + length + "d", 0);
    }

    public String getExtension() {
        return this.name().toLowerCase(Locale.ROOT);
    }

    public MessageDigest get() {
        try {
            return MessageDigest.getInstance(algo);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e); // Never happens
        }
    }

    public String hash(File file) throws IOException {
        return hash(Files.readAllBytes(file.toPath()));
    }

    public String hash(Iterable files) throws IOException {
        MessageDigest hash = get();

        for (File file : files) {
            if (!file.exists())
                continue;
            hash.update(Files.readAllBytes(file.toPath()));
        }
        return pad(new BigInteger(1, hash.digest()).toString(16));
    }

    public String hash(@Nullable String data) {
        return hash(data == null ? new byte[0] : data.getBytes(StandardCharsets.UTF_8));
    }

    public String hash(InputStream stream) throws IOException {
        return hash(IOUtils.toByteArray(stream));
    }

    public String hash(byte[] data) {
        return pad(new BigInteger(1, get().digest(data)).toString(16));
    }

    public String pad(String hash) {
        return (pad + hash).substring(hash.length());
    }
}