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// Copyright 2014 Google Inc. All rights reserved.
//
// 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 com.google.devtools.build.zip;
import java.util.Arrays;
/**
* A holder class for extra data in a ZIP entry.
*/
public final class ExtraData {
static final int ID_OFFSET = 0;
static final int LENGTH_OFFSET = 2;
static final int FIXED_DATA_SIZE = 4;
private final int index;
private final byte[] buffer;
/**
* Creates a new {@link ExtraData} record with the specified id and data.
*
* @param id the ID tag for this extra data record
* @param data the data payload for this extra data record
*/
public ExtraData(short id, byte[] data) {
if (data.length > 0xffff) {
throw new IllegalArgumentException(String.format("Data is too long. Is %d; max %d",
data.length, 0xffff));
}
index = 0;
buffer = new byte[FIXED_DATA_SIZE + data.length];
ZipUtil.shortToLittleEndian(buffer, ID_OFFSET, id);
ZipUtil.shortToLittleEndian(buffer, LENGTH_OFFSET, (short) data.length);
System.arraycopy(data, 0, buffer, FIXED_DATA_SIZE, data.length);
}
/**
* Creates a new {@link ExtraData} record using the buffer as the backing data store.
*
* <p><em>NOTE:</em> does not perform any defensive copying. Any modification to the buffer will
* alter the extra data record and can make it invalid.
*
* @param buffer the array containing the extra data record
* @param index the index where the extra data record is located
* @throws IllegalArgumentException if buffer does not contain a well formed extra data record
* at index
*/
ExtraData(byte[] buffer, int index) {
if (index >= buffer.length) {
throw new IllegalArgumentException("index past end of buffer");
}
if (buffer.length - index < FIXED_DATA_SIZE) {
throw new IllegalArgumentException("incomplete extra data entry in buffer");
}
int length = ZipUtil.getUnsignedShort(buffer, index + LENGTH_OFFSET);
if (buffer.length - index - FIXED_DATA_SIZE < length) {
throw new IllegalArgumentException("incomplete extra data entry in buffer");
}
this.buffer = buffer;
this.index = index;
}
/** Returns the Id of the extra data record. */
public short getId() {
return ZipUtil.get16(buffer, index + ID_OFFSET);
}
/** Returns the total length of the extra data record in bytes. */
public int getLength() {
return getDataLength() + FIXED_DATA_SIZE;
}
/** Returns the length of the data payload of the extra data record in bytes. */
public int getDataLength() {
return ZipUtil.getUnsignedShort(buffer, index + LENGTH_OFFSET);
}
/** Returns a byte array copy of the data payload. */
public byte[] getData() {
return Arrays.copyOfRange(buffer, index + FIXED_DATA_SIZE, index + getLength());
}
/** Returns a byte array copy of the entire record. */
public byte[] getBytes() {
return Arrays.copyOfRange(buffer, index, index + getLength());
}
/** Returns the byte at index from the entire record. */
byte getByte(int index) {
return buffer[this.index + index];
}
}
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