//
// 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.cloud.utils.storage;
import java.io.IOException;
import java.io.InputStream;
import com.cloud.utils.NumbersUtil;
public final class QCOW2Utils {
private static final int VIRTUALSIZE_HEADER_LOCATION = 24;
private static final int VIRTUALSIZE_HEADER_LENGTH = 8;
/**
* Private constructor -> This utility class cannot be instantiated.
*/
private QCOW2Utils() {}
/**
* @return the header location of the virtual size field.
*/
public static int getVirtualSizeHeaderLocation() {
return VIRTUALSIZE_HEADER_LOCATION;
}
/**
* @param inputStream The QCOW2 object in stream format.
* @return The virtual size of the QCOW2 object.
*/
public static long getVirtualSize(InputStream inputStream) throws IOException {
byte[] bytes = new byte[VIRTUALSIZE_HEADER_LENGTH];
if (inputStream.skip(VIRTUALSIZE_HEADER_LOCATION) != VIRTUALSIZE_HEADER_LOCATION) {
throw new IOException("Unable to skip to the virtual size header");
}
if (inputStream.read(bytes) != VIRTUALSIZE_HEADER_LENGTH) {
throw new IOException("Unable to properly read the size");
}
return NumbersUtil.bytesToLong(bytes);
}
}