org.apache.axiom.attachments.PushbackFilePartInputStream Maven / Gradle / Ivy

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The Axiom API
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/*
 * Copyright 2004,2005 The Apache Software Foundation.
 *
 * Licensed 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 org.apache.axiom.attachments;

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

public class PushbackFilePartInputStream extends InputStream {

    MIMEBodyPartInputStream inStream;

    byte[] buffer;

    int count;

    /**
     * @param inStream
     * @param buffer
     */
    public PushbackFilePartInputStream(MIMEBodyPartInputStream inStream,
                                       byte[] buffer) {
        super();
        this.inStream = inStream;
        this.buffer = buffer;
        count = buffer.length;
    }

    public int read() throws IOException {
        int data;
        if (count > 0) {
            byte byteValue = buffer[buffer.length - count];
            // converting the byte to unsigned int value
            data = byteValue & 0xff;
            count--;
        } else {
            data = inStream.read();
        }
        return data;
    }

    public int read(byte b[], int off, int len) throws IOException {
        if (count > 0) {
            if (b == null) {
                throw new NullPointerException();
            } else if ((off < 0) || (off > b.length) || (len < 0) || ((off + len) > b.length)
                    || ((off + len) < 0)) {
                throw new IndexOutOfBoundsException();
            } else if (len == 0) {
                return 0;
            }
            int bytesCopied;
            if (count < len) {
                System.arraycopy(buffer, (buffer.length - count), b, off, count);
                bytesCopied = count;
                count = 0;
                return bytesCopied;
            }
            System.arraycopy(buffer, (buffer.length - count), b, off, len);
            count -= len;
            return len;
        }
        return inStream.read(b, off, len);
    }

    public int available() throws IOException {
        return count + inStream.available();
    }
}