314 lines
13 KiB
Java
314 lines
13 KiB
Java
/*
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* Copyright (c) 2009, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/**
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* IOUtils: A collection of IO-related public static methods.
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*/
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package sun.misc;
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import java.io.EOFException;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Objects;
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public class IOUtils {
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private static final int DEFAULT_BUFFER_SIZE = 8192;
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/**
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* The maximum size of array to allocate.
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* Some VMs reserve some header words in an array.
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* Attempts to allocate larger arrays may result in
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* OutOfMemoryError: Requested array size exceeds VM limit
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*/
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private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
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/**
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* Read exactly {@code length} of bytes from {@code in}.
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*
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* <p> Note that this method is safe to be called with unknown large
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* {@code length} argument. The memory used is proportional to the
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* actual bytes available. An exception is thrown if there are not
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* enough bytes in the stream.
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*
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* @param is input stream, must not be null
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* @param length number of bytes to read
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* @return bytes read
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* @throws EOFException if there are not enough bytes in the stream
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* @throws IOException if an I/O error occurs or {@code length} is negative
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* @throws OutOfMemoryError if an array of the required size cannot be
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* allocated.
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*/
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public static byte[] readExactlyNBytes(InputStream is, int length)
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throws IOException {
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if (length < 0) {
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throw new IOException("length cannot be negative: " + length);
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}
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byte[] data = readNBytes(is, length);
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if (data.length < length) {
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throw new EOFException();
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}
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return data;
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}
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/**
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* Reads all remaining bytes from the input stream. This method blocks until
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* all remaining bytes have been read and end of stream is detected, or an
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* exception is thrown. This method does not close the input stream.
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*
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* <p> When this stream reaches end of stream, further invocations of this
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* method will return an empty byte array.
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*
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* <p> Note that this method is intended for simple cases where it is
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* convenient to read all bytes into a byte array. It is not intended for
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* reading input streams with large amounts of data.
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*
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* <p> The behavior for the case where the input stream is <i>asynchronously
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* closed</i>, or the thread interrupted during the read, is highly input
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* stream specific, and therefore not specified.
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*
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* <p> If an I/O error occurs reading from the input stream, then it may do
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* so after some, but not all, bytes have been read. Consequently the input
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* stream may not be at end of stream and may be in an inconsistent state.
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* It is strongly recommended that the stream be promptly closed if an I/O
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* error occurs.
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*
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* @implSpec
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* This method invokes {@link #readNBytes(int)} with a length of
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* {@link Integer#MAX_VALUE}.
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*
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* @param is input stream, must not be null
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* @return a byte array containing the bytes read from this input stream
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* @throws IOException if an I/O error occurs
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* @throws OutOfMemoryError if an array of the required size cannot be
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* allocated.
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*
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* @since 1.9
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*/
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public static byte[] readAllBytes(InputStream is) throws IOException {
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return readNBytes(is, Integer.MAX_VALUE);
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}
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/**
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* Reads up to a specified number of bytes from the input stream. This
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* method blocks until the requested number of bytes have been read, end
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* of stream is detected, or an exception is thrown. This method does not
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* close the input stream.
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*
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* <p> The length of the returned array equals the number of bytes read
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* from the stream. If {@code len} is zero, then no bytes are read and
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* an empty byte array is returned. Otherwise, up to {@code len} bytes
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* are read from the stream. Fewer than {@code len} bytes may be read if
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* end of stream is encountered.
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*
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* <p> When this stream reaches end of stream, further invocations of this
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* method will return an empty byte array.
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*
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* <p> Note that this method is intended for simple cases where it is
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* convenient to read the specified number of bytes into a byte array. The
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* total amount of memory allocated by this method is proportional to the
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* number of bytes read from the stream which is bounded by {@code len}.
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* Therefore, the method may be safely called with very large values of
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* {@code len} provided sufficient memory is available.
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*
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* <p> The behavior for the case where the input stream is <i>asynchronously
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* closed</i>, or the thread interrupted during the read, is highly input
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* stream specific, and therefore not specified.
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*
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* <p> If an I/O error occurs reading from the input stream, then it may do
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* so after some, but not all, bytes have been read. Consequently the input
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* stream may not be at end of stream and may be in an inconsistent state.
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* It is strongly recommended that the stream be promptly closed if an I/O
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* error occurs.
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*
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* @implNote
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* The number of bytes allocated to read data from this stream and return
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* the result is bounded by {@code 2*(long)len}, inclusive.
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*
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* @param is input stream, must not be null
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* @param len the maximum number of bytes to read
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* @return a byte array containing the bytes read from this input stream
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* @throws IllegalArgumentException if {@code length} is negative
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* @throws IOException if an I/O error occurs
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* @throws OutOfMemoryError if an array of the required size cannot be
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* allocated.
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*
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* @since 11
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*/
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public static byte[] readNBytes(InputStream is, int len) throws IOException {
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if (len < 0) {
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throw new IllegalArgumentException("len < 0");
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}
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List<byte[]> bufs = null;
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byte[] result = null;
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int total = 0;
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int remaining = len;
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int n;
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do {
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byte[] buf = new byte[Math.min(remaining, DEFAULT_BUFFER_SIZE)];
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int nread = 0;
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// read to EOF which may read more or less than buffer size
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while ((n = is.read(buf, nread,
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Math.min(buf.length - nread, remaining))) > 0) {
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nread += n;
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remaining -= n;
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}
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if (nread > 0) {
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if (MAX_BUFFER_SIZE - total < nread) {
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throw new OutOfMemoryError("Required array size too large");
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}
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total += nread;
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if (result == null) {
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result = buf;
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} else {
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if (bufs == null) {
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bufs = new ArrayList<>();
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bufs.add(result);
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}
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bufs.add(buf);
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}
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}
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// if the last call to read returned -1 or the number of bytes
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// requested have been read then break
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} while (n >= 0 && remaining > 0);
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if (bufs == null) {
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if (result == null) {
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return new byte[0];
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}
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return result.length == total ?
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result : Arrays.copyOf(result, total);
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}
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result = new byte[total];
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int offset = 0;
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remaining = total;
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for (byte[] b : bufs) {
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int count = Math.min(b.length, remaining);
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System.arraycopy(b, 0, result, offset, count);
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offset += count;
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remaining -= count;
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}
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return result;
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}
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/**
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* Reads the requested number of bytes from the input stream into the given
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* byte array. This method blocks until {@code len} bytes of input data have
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* been read, end of stream is detected, or an exception is thrown. The
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* number of bytes actually read, possibly zero, is returned. This method
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* does not close the input stream.
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*
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* <p> In the case where end of stream is reached before {@code len} bytes
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* have been read, then the actual number of bytes read will be returned.
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* When this stream reaches end of stream, further invocations of this
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* method will return zero.
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*
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* <p> If {@code len} is zero, then no bytes are read and {@code 0} is
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* returned; otherwise, there is an attempt to read up to {@code len} bytes.
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*
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* <p> The first byte read is stored into element {@code b[off]}, the next
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* one in to {@code b[off+1]}, and so on. The number of bytes read is, at
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* most, equal to {@code len}. Let <i>k</i> be the number of bytes actually
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* read; these bytes will be stored in elements {@code b[off]} through
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* {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i>
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* {@code ]} through {@code b[off+len-1]} unaffected.
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*
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* <p> The behavior for the case where the input stream is <i>asynchronously
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* closed</i>, or the thread interrupted during the read, is highly input
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* stream specific, and therefore not specified.
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*
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* <p> If an I/O error occurs reading from the input stream, then it may do
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* so after some, but not all, bytes of {@code b} have been updated with
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* data from the input stream. Consequently the input stream and {@code b}
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* may be in an inconsistent state. It is strongly recommended that the
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* stream be promptly closed if an I/O error occurs.
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*
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* @param is input stream, must not be null
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* @param b the byte array into which the data is read
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* @param off the start offset in {@code b} at which the data is written
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* @param len the maximum number of bytes to read
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* @return the actual number of bytes read into the buffer
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* @throws IOException if an I/O error occurs
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* @throws NullPointerException if {@code b} is {@code null}
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* @throws IndexOutOfBoundsException If {@code off} is negative, {@code len}
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* is negative, or {@code len} is greater than {@code b.length - off}
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*
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* @since 1.9
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*/
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public static int readNBytes(InputStream is, byte[] b, int off, int len) throws IOException {
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Objects.requireNonNull(b);
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if (off < 0 || len < 0 || len > b.length - off)
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throw new IndexOutOfBoundsException();
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int n = 0;
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while (n < len) {
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int count = is.read(b, off + n, len - n);
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if (count < 0)
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break;
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n += count;
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}
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return n;
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}
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/**
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* Compatibility wrapper for third party users of
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* {@code sun.misc.IOUtils.readFully} following its
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* removal in JDK-8231139.
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*
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* Read up to {@code length} of bytes from {@code in}
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* until EOF is detected.
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*
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* @param is input stream, must not be null
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* @param length number of bytes to read
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* @param readAll if true, an EOFException will be thrown if not enough
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* bytes are read.
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* @return bytes read
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* @throws EOFException if there are not enough bytes in the stream
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* @throws IOException if an I/O error occurs or {@code length} is negative
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* @throws OutOfMemoryError if an array of the required size cannot be
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* allocated.
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*/
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public static byte[] readFully(InputStream is, int length, boolean readAll)
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throws IOException {
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if (length < 0) {
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throw new IOException("length cannot be negative: " + length);
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}
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if (readAll) {
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return readExactlyNBytes(is, length);
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} else {
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return readNBytes(is, length);
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}
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}
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}
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