InputStream that reads at most N bytes from underlying stream

BoundedInputStream.java

package io.github.ncruces.utils;

import java.io.IOException;
import java.io.InputStream;

import static java.lang.Math.min;

public class BoundedInputStream extends InputStream {
    private final InputStream in;
    private final long max;
    private long pos;
    private long mark;

    public BoundedInputStream(InputStream in, long max) {
        if (in == null) throw new NullPointerException();
        if (max < 0) throw new IllegalArgumentException();
        this.in = in;
        this.max = max;
    }

    @Override
    public int read() throws IOException {
        if (pos >= max) return -1;
        int read = in.read();
        if (read >= 0) ++pos;
        else pos = max;
        return read;
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        if (len == 0) return 0;
        if (pos >= max) return -1;
        int read = in.read(b, off, (int)min(len, max - pos));
        if (read >= 0) pos += read;
        else pos = max;
        return read;
    }

    @Override
    public long skip(long n) throws IOException {
        long skipped = in.skip(min(n, max - pos));
        pos += skipped;
        return skipped;
    }

    @Override
    public int available() throws IOException {
        return (int)min(in.available(), max - pos);
    }

    @Override
    public boolean markSupported() {
        return in.markSupported();
    }

    @Override
    public synchronized void mark(int readlimit) {
        in.mark(readlimit);
        mark = pos;
    }

    @Override
    public synchronized void reset() throws IOException {
        in.reset();
        pos = mark;
    }
}