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Apache Commons Compress software defines an API for working with
compression and archive formats. These include: bzip2, gzip, pack200,
lzma, xz, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4,
Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
/*
* 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 org.apache.commons.compress.utils;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Utility methods for reading and writing bytes.
* @since 1.14
*/
public final class ByteUtils {
private ByteUtils() { /* no instances */ }
/**
* Used to supply bytes.
* @since 1.14
*/
public interface ByteSupplier {
/**
* The contract is similar to {@link InputStream#read()}, return
* the byte as an unsigned int, -1 if there are no more bytes.
* @return the supplied byte or -1 if there are no more bytes
* @throws IOException if supplying fails
*/
int getAsByte() throws IOException;
}
/**
* Used to consume bytes.
* @since 1.14
*/
public interface ByteConsumer {
/**
* The contract is similar to {@link OutputStream#write(int)},
* consume the lower eight bytes of the int as a byte.
* @param b the byte to consume
* @throws IOException if consuming fails
*/
void accept(int b) throws IOException;
}
/**
* Reads the given byte array as a little endian long.
* @param bytes the byte array to convert
* @return the number read
*/
public static long fromLittleEndian(byte[] bytes) {
return fromLittleEndian(bytes, 0, bytes.length);
}
/**
* Reads the given byte array as a little endian long.
* @param bytes the byte array to convert
* @param off the offset into the array that starts the value
* @param length the number of bytes representing the value
* @return the number read
* @throws IllegalArgumentException if len is bigger than eight
*/
public static long fromLittleEndian(byte[] bytes, final int off, final int length) {
checkReadLength(length);
long l = 0;
for (int i = 0; i < length; i++) {
l |= (bytes[off + i] & 0xffL) << (8 * i);
}
return l;
}
/**
* Reads the given number of bytes from the given stream as a little endian long.
* @param in the stream to read from
* @param length the number of bytes representing the value
* @return the number read
* @throws IllegalArgumentException if len is bigger than eight
* @throws IOException if reading fails or the stream doesn't
* contain the given number of bytes anymore
*/
public static long fromLittleEndian(InputStream in, int length) throws IOException {
// somewhat duplicates the ByteSupplier version in order to save the creation of a wrapper object
checkReadLength(length);
long l = 0;
for (int i = 0; i < length; i++) {
long b = in.read();
if (b == -1) {
throw new IOException("premature end of data");
}
l |= (b << (i * 8));
}
return l;
}
/**
* Reads the given number of bytes from the given supplier as a little endian long.
*
* Typically used by our InputStreams that need to count the
* bytes read as well.
*
* @param supplier the supplier for bytes
* @param length the number of bytes representing the value
* @return the number read
* @throws IllegalArgumentException if len is bigger than eight
* @throws IOException if the supplier fails or doesn't supply the
* given number of bytes anymore
*/
public static long fromLittleEndian(ByteSupplier supplier, final int length) throws IOException {
checkReadLength(length);
long l = 0;
for (int i = 0; i < length; i++) {
long b = supplier.getAsByte();
if (b == -1) {
throw new IOException("premature end of data");
}
l |= (b << (i * 8));
}
return l;
}
/**
* Reads the given number of bytes from the given input as little endian long.
* @param in the input to read from
* @param length the number of bytes representing the value
* @return the number read
* @throws IllegalArgumentException if len is bigger than eight
* @throws IOException if reading fails or the stream doesn't
* contain the given number of bytes anymore
*/
public static long fromLittleEndian(DataInput in, int length) throws IOException {
// somewhat duplicates the ByteSupplier version in order to save the creation of a wrapper object
checkReadLength(length);
long l = 0;
for (int i = 0; i < length; i++) {
long b = in.readUnsignedByte();
l |= (b << (i * 8));
}
return l;
}
/**
* Inserts the given value into the array as a little endian
* sequence of the given length starting at the given offset.
* @param b the array to write into
* @param value the value to insert
* @param off the offset into the array that receives the first byte
* @param length the number of bytes to use to represent the value
*/
public static void toLittleEndian(final byte[] b, final long value, final int off, final int length) {
long num = value;
for (int i = 0; i < length; i++) {
b[off + i] = (byte) (num & 0xff);
num >>= 8;
}
}
/**
* Writes the given value to the given stream as a little endian
* array of the given length.
* @param out the stream to write to
* @param value the value to write
* @param length the number of bytes to use to represent the value
* @throws IOException if writing fails
*/
public static void toLittleEndian(OutputStream out, final long value, final int length)
throws IOException {
// somewhat duplicates the ByteConsumer version in order to save the creation of a wrapper object
long num = value;
for (int i = 0; i < length; i++) {
out.write((int) (num & 0xff));
num >>= 8;
}
}
/**
* Provides the given value to the given consumer as a little endian
* sequence of the given length.
* @param consumer the consumer to provide the bytes to
* @param value the value to provide
* @param length the number of bytes to use to represent the value
* @throws IOException if writing fails
*/
public static void toLittleEndian(ByteConsumer consumer, final long value, final int length)
throws IOException {
long num = value;
for (int i = 0; i < length; i++) {
consumer.accept((int) (num & 0xff));
num >>= 8;
}
}
/**
* Writes the given value to the given stream as a little endian
* array of the given length.
* @param out the output to write to
* @param value the value to write
* @param length the number of bytes to use to represent the value
* @throws IOException if writing fails
*/
public static void toLittleEndian(DataOutput out, final long value, final int length)
throws IOException {
// somewhat duplicates the ByteConsumer version in order to save the creation of a wrapper object
long num = value;
for (int i = 0; i < length; i++) {
out.write((int) (num & 0xff));
num >>= 8;
}
}
/**
* {@link ByteSupplier} based on {@link InputStream}.
* @since 1.14
*/
public static class InputStreamByteSupplier implements ByteSupplier {
private final InputStream is;
public InputStreamByteSupplier(InputStream is) {
this.is = is;
}
@Override
public int getAsByte() throws IOException {
return is.read();
}
}
/**
* {@link ByteConsumer} based on {@link OutputStream}.
* @since 1.14
*/
public static class OutputStreamByteConsumer implements ByteConsumer {
private final OutputStream os;
public OutputStreamByteConsumer(OutputStream os) {
this.os = os;
}
@Override
public void accept(int b) throws IOException {
os.write(b);
}
}
private static final void checkReadLength(int length) {
if (length > 8) {
throw new IllegalArgumentException("can't read more than eight bytes into a long value");
}
}
}