com.jingtum.core.bouncycastle.asn1.DefiniteLengthInputStream Maven / Gradle / Ivy

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/*
 * Copyright www.jingtum.com Inc. 
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package com.jingtum.core.bouncycastle.asn1;

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

import com.jingtum.core.bouncycastle.util.io.Streams;

class DefiniteLengthInputStream
        extends LimitedInputStream
{
    private static final byte[] EMPTY_BYTES = new byte[0];

    private final int _originalLength;
    private int _remaining;

    DefiniteLengthInputStream(
        InputStream in,
        int         length)
    {
        super(in, length);

        if (length < 0)
        {
            throw new IllegalArgumentException("negative lengths not allowed");
        }

        this._originalLength = length;
        this._remaining = length;

        if (length == 0)
        {
            setParentEofDetect(true);
        }
    }

    int getRemaining()
    {
        return _remaining;
    }

    public int read()
        throws IOException
    {
        if (_remaining == 0)
        {
            return -1;
        }

        int b = _in.read();

        if (b < 0)
        {
            throw new EOFException("DEF length " + _originalLength + " object truncated by " + _remaining);
        }

        if (--_remaining == 0)
        {
            setParentEofDetect(true);
        }

        return b;
    }

    public int read(byte[] buf, int off, int len)
        throws IOException
    {
        if (_remaining == 0)
        {
            return -1;
        }

        int toRead = Math.min(len, _remaining);
        int numRead = _in.read(buf, off, toRead);

        if (numRead < 0)
        {
            throw new EOFException("DEF length " + _originalLength + " object truncated by " + _remaining);
        }

        if ((_remaining -= numRead) == 0)
        {
            setParentEofDetect(true);
        }

        return numRead;
    }

    byte[] toByteArray()
        throws IOException
    {
        if (_remaining == 0)
        {
            return EMPTY_BYTES;
        }

        byte[] bytes = new byte[_remaining];
        if ((_remaining -= Streams.readFully(_in, bytes)) != 0)
        {
            throw new EOFException("DEF length " + _originalLength + " object truncated by " + _remaining);
        }
        setParentEofDetect(true);
        return bytes;
    }
}