com.github.robtimus.io.stream.HexInputStream Maven / Gradle / Ivy
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/*
* HexInputStream.java
* Copyright 2020 Rob Spoor
*
* 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.github.robtimus.io.stream;
import static com.github.robtimus.io.stream.StreamUtils.checkStartAndEnd;
import static com.github.robtimus.io.stream.StreamUtils.streamClosedException;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.Objects;
import java.util.Optional;
/**
* An input stream that converts hex into bytes.
*
* When a hex input stream is closed, its source will be closed as well.
*
* @author Rob Spoor
*/
public final class HexInputStream extends InputStream {
private static final int READ_BUFFER_SIZE = 1024;
private Reader source;
private char[] readBuffer;
private IOException exception;
/**
* Creates a new hex input stream.
*
* @param source The reader that forms the source of the hex characters.
* @throws NullPointerException If the given reader is {@code null}.
*/
public HexInputStream(Reader source) {
this.source = Objects.requireNonNull(source);
}
private void ensureOpen() throws IOException {
if (source == null) {
throw streamClosedException();
}
}
private void checkException() throws IOException {
if (exception != null) {
throw exception;
}
}
@Override
public int read() throws IOException {
ensureOpen();
checkException();
if (readBuffer == null) {
readBuffer = new char[READ_BUFFER_SIZE];
}
int read = read(readBuffer, 2);
if (read == -1) {
return -1;
}
int high = convert(readBuffer[0]);
int low = convert(readBuffer[1]);
return combine(high, low) & 0xFF;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
ensureOpen();
checkException();
char[] cbuf;
int lenInHex = len * 2;
if (lenInHex <= READ_BUFFER_SIZE) {
if (readBuffer == null) {
readBuffer = new char[READ_BUFFER_SIZE];
}
cbuf = readBuffer;
} else {
// Don't permanently allocate very large buffers.
cbuf = new char[lenInHex];
}
int read = read(cbuf, lenInHex);
if (read == -1) {
return -1;
}
for (int i = off, j = 0; j < read; i++, j += 2) {
int high = convert(cbuf[j]);
int low = convert(cbuf[j + 1]);
b[i] = combine(high, low);
}
return read / 2;
}
private int read(char[] cbuf, int lenInHex) throws IOException {
int read = source.read(cbuf, 0, lenInHex);
if (read == -1) {
return -1;
}
while ((read & 1) == 1) {
int n = source.read(cbuf, read, lenInHex - read);
if (n == -1) {
// no more data and an odd number of characters - premature EOF
exception = new EOFException(Messages.hex.eof());
throw exception;
}
read += n;
}
return read;
}
private int convert(char c) throws IOException {
int value = Character.digit(c, 16);
if (value == -1) {
exception = new IOException(Messages.hex.invalidChar(c));
throw exception;
}
return value;
}
@Override
public int available() throws IOException {
ensureOpen();
return 0;
}
@Override
public void close() throws IOException {
if (source != null) {
source.close();
source = null;
}
}
/**
* Converts a hex representation into a byte array.
*
* @param hex The character sequence with the hex representation to convert.
* @return The bytes from the given hex representation.
* @throws NullPointerException If the given character sequence is {@code null}.
* @throws IllegalArgumentException If the given character sequence does not contain a valid hex representation.
*/
public static byte[] decode(CharSequence hex) {
return decode(hex, 0, hex.length());
}
/**
* Converts a hex representation into a byte array.
*
* @param hex The character sequence with the hex representation to convert.
* @param start The start index of the character sequence of the hex representation to convert, inclusive.
* @param end The end index of the character sequence of the hex representation to convert, exclusive.
* @return The bytes from the given hex representation.
* @throws NullPointerException If the given character sequence is {@code null}.
* @throws IndexOutOfBoundsException If the given start index is negative,
* the given end index is larger than the given character sequence's length,
* or the given start index is larger than the given end index.
* @throws IllegalArgumentException If the given character sequence does not contain a valid hex representation.
*/
public static byte[] decode(CharSequence hex, int start, int end) {
checkStartAndEnd(hex, start, end);
int length = end - start;
if ((length & 1) == 1) {
throw new IllegalArgumentException(Messages.hex.eof());
}
byte[] b = new byte[length / 2];
for (int i = 0, j = start; j < end; i++, j += 2) {
int high = convert(hex, j);
int low = convert(hex, j + 1);
b[i] = combine(high, low);
}
return b;
}
private static int convert(CharSequence hex, int index) {
char c = hex.charAt(index);
int value = Character.digit(c, 16);
if (value == -1) {
throw new IllegalArgumentException(Messages.hex.invalidChar(c));
}
return value;
}
/**
* Attempts to converts a hex representation into a byte array.
*
* @param hex The character sequence with the hex representation to convert.
* @return An {@link Optional} with the bytes from the given hex representation,
* or {@link Optional#empty()} if the character sequence is {@code null} or does not contain a valid hex representation.
* @throws IndexOutOfBoundsException If the given start index is negative,
* the given end index is larger than the given character sequence's length,
* or the given start index is larger than the given end index.
*/
public static Optional tryDecode(CharSequence hex) {
return hex == null ? Optional.empty() : tryDecode(hex, 0, hex.length());
}
/**
* Attempts to converts a hex representation into a byte array.
*
* @param hex The character sequence with the hex representation to convert.
* @param start The start index of the character sequence of the hex representation to convert, inclusive.
* @param end The end index of the character sequence of the hex representation to convert, exclusive.
* @return An {@link Optional} with the bytes from the given hex representation,
* or {@link Optional#empty()} if the character sequence is {@code null} or does not contain a valid hex representation.
* @throws IndexOutOfBoundsException If the given start index is negative,
* the given end index is larger than the given character sequence's length,
* or the given start index is larger than the given end index.
*/
public static Optional tryDecode(CharSequence hex, int start, int end) {
if (hex == null) {
return Optional.empty();
}
checkStartAndEnd(hex, start, end);
int length = end - start;
if ((length & 1) == 1) {
return Optional.empty();
}
byte[] b = new byte[length / 2];
for (int i = 0, j = start; j < end; i++, j += 2) {
int high = tryConvert(hex, j);
int low = tryConvert(hex, j + 1);
if (high == -1 || low == -1) {
return Optional.empty();
}
b[i] = combine(high, low);
}
return Optional.of(b);
}
private static int tryConvert(CharSequence hex, int index) {
char c = hex.charAt(index);
return Character.digit(c, 16);
}
private static byte combine(int high, int low) {
return (byte) ((high << 4 | low) & 0xFF);
}
}