package org.apache.lucene.util;
/**
* 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.
*/
import java.io.IOException;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexFormatTooNewException;
import org.apache.lucene.index.IndexFormatTooOldException;
import org.apache.lucene.store.DataInput;
import org.apache.lucene.store.DataOutput;
/**
* @lucene.experimental
*/
public final class CodecUtil {
private CodecUtil() {} // no instance
private final static int CODEC_MAGIC = 0x3fd76c17;
public static DataOutput writeHeader(DataOutput out, String codec, int version)
throws IOException {
BytesRef bytes = new BytesRef(codec);
if (bytes.length != codec.length() || bytes.length >= 128) {
throw new IllegalArgumentException("codec must be simple ASCII, less than 128 characters in length [got " + codec + "]");
}
out.writeInt(CODEC_MAGIC);
out.writeString(codec);
out.writeInt(version);
return out;
}
public static int headerLength(String codec) {
return 9+codec.length();
}
public static int checkHeader(DataInput in, String codec, int minVersion, int maxVersion)
throws IOException {
// Safety to guard against reading a bogus string:
final int actualHeader = in.readInt();
if (actualHeader != CODEC_MAGIC) {
throw new CorruptIndexException("codec header mismatch: actual header=" + actualHeader + " vs expected header=" + CODEC_MAGIC + " (resource: " + in + ")");
}
final String actualCodec = in.readString();
if (!actualCodec.equals(codec)) {
throw new CorruptIndexException("codec mismatch: actual codec=" + actualCodec + " vs expected codec=" + codec + " (resource: " + in + ")");
}
final int actualVersion = in.readInt();
if (actualVersion < minVersion) {
throw new IndexFormatTooOldException(in, actualVersion, minVersion, maxVersion);
}
if (actualVersion > maxVersion) {
throw new IndexFormatTooNewException(in, actualVersion, minVersion, maxVersion);
}
return actualVersion;
}
}