com.github.isaichkindanila.crypt.lib.file.FileEraser Maven / Gradle / Ivy

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Simple Java library for stream ciphers based encryption
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package com.github.isaichkindanila.crypt.lib.file;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

/**
 * Class used to erase files.
 */
@SuppressWarnings({"WeakerAccess", "NonAtomicOperationOnVolatileField", "ResultOfMethodCallIgnored"})
public class FileEraser {
    private final byte[] ZEROS = new byte[IOHandler.BUFFER_SIZE];
    private final List files;

    private volatile long done;
    private long total;

    /**
     * @param files files to be erased
     */
    public FileEraser(File... files) {
        this(Arrays.asList(files));
    }

    /**
     * @param files files to be erased
     */
    public FileEraser(Collection files) {
        this.files = new ArrayList<>();
        this.total = 0;

        files.forEach(this::populateList);
    }

    private void populateList(File file) {
        if (file.isDirectory()) {
            File[] children = file.listFiles();

            if (children != null) {
                for (File f : children) {
                    populateList(f);
                }
            }

            files.add(file);
        } else {
            files.add(file);
            total += file.length();
        }
    }

    private void eraseFile(File file) throws IOException {
        long size = file.length();

        if (size > 0) {
            int totalLoops = (int) (size / ZEROS.length);
            int lastLoop = (int) (size % ZEROS.length);

            try (FileOutputStream out = new FileOutputStream(file)) {
                for (int i = 0; i < totalLoops; i++) {
                    out.write(ZEROS);
                    done += ZEROS.length;
                }

                out.write(ZEROS, 0, lastLoop);
                done += lastLoop;
            }
        }
    }

    /**
     * Fills files with zeros and then deletes them.
     *
     * @throws IOException if IOException occurs
     */
    public void erase() throws IOException {
        for (File f : files) {
            if (f.isFile()) {
                eraseFile(f);
            }

            f.delete();
        }
    }

    /**
     * Returns value in range [0, 1] representing encryption progress,
     * where 0 means "not started yet" and 1 means "already finished".
     *
     * @return double value in range [0, 1]
     */
    public double progress() {
        return total == 0 ? 1.0 : 1.0 * done / total;
    }
}