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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 and up. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.

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package org.bouncycastle.cms.jcajce;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.InflaterInputStream;

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.operator.InputExpander;
import org.bouncycastle.operator.InputExpanderProvider;
import org.bouncycastle.util.io.StreamOverflowException;

public class ZlibExpanderProvider
    implements InputExpanderProvider
{
    private final long limit;

    /**
     * Base constructor. Create an expander which will not limit the size of any objects expanded in the stream.
     */
    public ZlibExpanderProvider()
    {
        this.limit = -1;
    }

    /**
     * Create a provider which caps the number of expanded bytes that can be produced when the
     * compressed stream is parsed.
     *
     * @param limit max number of bytes allowed in an expanded stream.
     */
    public ZlibExpanderProvider(long limit)
    {
        this.limit = limit;
    }

    public InputExpander get(final AlgorithmIdentifier algorithm)
    {
        return new InputExpander()
        {
            public AlgorithmIdentifier getAlgorithmIdentifier()
            {
                return algorithm;
            }

            public InputStream getInputStream(InputStream comIn)
            {
                InputStream s = new InflaterInputStream(comIn);                
                if (limit >= 0)
                {
                    s = new LimitedInputStream(s, limit);
                }
                return s;
            }
        };
    }

    private static class LimitedInputStream
        extends FilterInputStream
    {
        private long remaining;

        public LimitedInputStream(InputStream input, long limit)
        {
            super(input);

            this.remaining = limit;
        }

        public int read()
            throws IOException
        {
            // Only a single 'extra' byte will ever be read
            if (remaining >= 0)
            {
                int b = super.in.read();
                if (b < 0 || --remaining >= 0)
                {
                    return b;
                }
            }

            throw new StreamOverflowException("expanded byte limit exceeded");
        }

        public int read(byte[] buf, int off, int len)
            throws IOException
        {
            if (len < 1)
            {
                // This will give correct exceptions/returns for strange lengths
                return super.read(buf, off, len);
            }

            if (remaining < 1)
            {
                // Will either return EOF or throw exception
                read();
                return -1;
            }

            /*
             * Limit the underlying request to 'remaining' bytes. This ensures the
             * caller will see the full 'limit' bytes before getting an exception.
             * Also, only one extra byte will ever be read.
             */
            int actualLen = (remaining > len ? len : (int)remaining);
            int numRead = super.in.read(buf, off, actualLen);
            if (numRead > 0)
            {
                remaining -= numRead;
            }
            return numRead;
        }
    }
}