| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.io; |
| |
| import libcore.io.IoUtils; |
| |
| /** |
| * A piped input stream should be connected |
| * to a piped output stream; the piped input |
| * stream then provides whatever data bytes |
| * are written to the piped output stream. |
| * Typically, data is read from a <code>PipedInputStream</code> |
| * object by one thread and data is written |
| * to the corresponding <code>PipedOutputStream</code> |
| * by some other thread. Attempting to use |
| * both objects from a single thread is not |
| * recommended, as it may deadlock the thread. |
| * The piped input stream contains a buffer, |
| * decoupling read operations from write operations, |
| * within limits. |
| * A pipe is said to be <a id="BROKEN"> <i>broken</i> </a> if a |
| * thread that was providing data bytes to the connected |
| * piped output stream is no longer alive. |
| * |
| * @author James Gosling |
| * @see java.io.PipedOutputStream |
| * @since 1.0 |
| */ |
| public class PipedInputStream extends InputStream { |
| boolean closedByWriter; |
| volatile boolean closedByReader; |
| boolean connected; |
| |
| /* REMIND: identification of the read and write sides needs to be |
| more sophisticated. Either using thread groups (but what about |
| pipes within a thread?) or using finalization (but it may be a |
| long time until the next GC). */ |
| Thread readSide; |
| Thread writeSide; |
| |
| private static final int DEFAULT_PIPE_SIZE = 1024; |
| |
| /** |
| * The default size of the pipe's circular input buffer. |
| * @since 1.1 |
| */ |
| // This used to be a constant before the pipe size was allowed |
| // to change. This field will continue to be maintained |
| // for backward compatibility. |
| protected static final int PIPE_SIZE = DEFAULT_PIPE_SIZE; |
| |
| /** |
| * The circular buffer into which incoming data is placed. |
| * @since 1.1 |
| */ |
| protected byte buffer[]; |
| |
| /** |
| * The index of the position in the circular buffer at which the |
| * next byte of data will be stored when received from the connected |
| * piped output stream. <code>in<0</code> implies the buffer is empty, |
| * <code>in==out</code> implies the buffer is full |
| * @since 1.1 |
| */ |
| protected int in = -1; |
| |
| /** |
| * The index of the position in the circular buffer at which the next |
| * byte of data will be read by this piped input stream. |
| * @since 1.1 |
| */ |
| protected int out = 0; |
| |
| /** |
| * Creates a <code>PipedInputStream</code> so |
| * that it is connected to the piped output |
| * stream <code>src</code>. Data bytes written |
| * to <code>src</code> will then be available |
| * as input from this stream. |
| * |
| * @param src the stream to connect to. |
| * @exception IOException if an I/O error occurs. |
| */ |
| public PipedInputStream(PipedOutputStream src) throws IOException { |
| this(src, DEFAULT_PIPE_SIZE); |
| } |
| |
| /** |
| * Creates a <code>PipedInputStream</code> so that it is |
| * connected to the piped output stream |
| * <code>src</code> and uses the specified pipe size for |
| * the pipe's buffer. |
| * Data bytes written to <code>src</code> will then |
| * be available as input from this stream. |
| * |
| * @param src the stream to connect to. |
| * @param pipeSize the size of the pipe's buffer. |
| * @exception IOException if an I/O error occurs. |
| * @exception IllegalArgumentException if {@code pipeSize <= 0}. |
| * @since 1.6 |
| */ |
| public PipedInputStream(PipedOutputStream src, int pipeSize) |
| throws IOException { |
| initPipe(pipeSize); |
| connect(src); |
| } |
| |
| /** |
| * Creates a <code>PipedInputStream</code> so |
| * that it is not yet {@linkplain #connect(java.io.PipedOutputStream) |
| * connected}. |
| * It must be {@linkplain java.io.PipedOutputStream#connect( |
| * java.io.PipedInputStream) connected} to a |
| * <code>PipedOutputStream</code> before being used. |
| */ |
| public PipedInputStream() { |
| initPipe(DEFAULT_PIPE_SIZE); |
| } |
| |
| /** |
| * Creates a <code>PipedInputStream</code> so that it is not yet |
| * {@linkplain #connect(java.io.PipedOutputStream) connected} and |
| * uses the specified pipe size for the pipe's buffer. |
| * It must be {@linkplain java.io.PipedOutputStream#connect( |
| * java.io.PipedInputStream) |
| * connected} to a <code>PipedOutputStream</code> before being used. |
| * |
| * @param pipeSize the size of the pipe's buffer. |
| * @exception IllegalArgumentException if {@code pipeSize <= 0}. |
| * @since 1.6 |
| */ |
| public PipedInputStream(int pipeSize) { |
| initPipe(pipeSize); |
| } |
| |
| private void initPipe(int pipeSize) { |
| if (pipeSize <= 0) { |
| throw new IllegalArgumentException("Pipe Size <= 0"); |
| } |
| buffer = new byte[pipeSize]; |
| } |
| |
| /** |
| * Causes this piped input stream to be connected |
| * to the piped output stream <code>src</code>. |
| * If this object is already connected to some |
| * other piped output stream, an <code>IOException</code> |
| * is thrown. |
| * <p> |
| * If <code>src</code> is an |
| * unconnected piped output stream and <code>snk</code> |
| * is an unconnected piped input stream, they |
| * may be connected by either the call: |
| * |
| * <pre><code>snk.connect(src)</code> </pre> |
| * <p> |
| * or the call: |
| * |
| * <pre><code>src.connect(snk)</code> </pre> |
| * <p> |
| * The two calls have the same effect. |
| * |
| * @param src The piped output stream to connect to. |
| * @exception IOException if an I/O error occurs. |
| */ |
| public void connect(PipedOutputStream src) throws IOException { |
| src.connect(this); |
| } |
| |
| /** |
| * Receives a byte of data. This method will block if no input is |
| * available. |
| * @param b the byte being received |
| * @exception IOException If the pipe is <a href="#BROKEN"> <code>broken</code></a>, |
| * {@link #connect(java.io.PipedOutputStream) unconnected}, |
| * closed, or if an I/O error occurs. |
| * @since 1.1 |
| */ |
| protected synchronized void receive(int b) throws IOException { |
| checkStateForReceive(); |
| writeSide = Thread.currentThread(); |
| if (in == out) |
| awaitSpace(); |
| if (in < 0) { |
| in = 0; |
| out = 0; |
| } |
| buffer[in++] = (byte)(b & 0xFF); |
| if (in >= buffer.length) { |
| in = 0; |
| } |
| } |
| |
| /** |
| * Receives data into an array of bytes. This method will |
| * block until some input is available. |
| * @param b the buffer into which the data is received |
| * @param off the start offset of the data |
| * @param len the maximum number of bytes received |
| * @exception IOException If the pipe is <a href="#BROKEN"> broken</a>, |
| * {@link #connect(java.io.PipedOutputStream) unconnected}, |
| * closed,or if an I/O error occurs. |
| */ |
| synchronized void receive(byte b[], int off, int len) throws IOException { |
| checkStateForReceive(); |
| writeSide = Thread.currentThread(); |
| int bytesToTransfer = len; |
| while (bytesToTransfer > 0) { |
| if (in == out) |
| awaitSpace(); |
| int nextTransferAmount = 0; |
| if (out < in) { |
| nextTransferAmount = buffer.length - in; |
| } else if (in < out) { |
| if (in == -1) { |
| in = out = 0; |
| nextTransferAmount = buffer.length - in; |
| } else { |
| nextTransferAmount = out - in; |
| } |
| } |
| if (nextTransferAmount > bytesToTransfer) |
| nextTransferAmount = bytesToTransfer; |
| assert(nextTransferAmount > 0); |
| System.arraycopy(b, off, buffer, in, nextTransferAmount); |
| bytesToTransfer -= nextTransferAmount; |
| off += nextTransferAmount; |
| in += nextTransferAmount; |
| if (in >= buffer.length) { |
| in = 0; |
| } |
| } |
| } |
| |
| private void checkStateForReceive() throws IOException { |
| if (!connected) { |
| throw new IOException("Pipe not connected"); |
| } else if (closedByWriter || closedByReader) { |
| throw new IOException("Pipe closed"); |
| } else if (readSide != null && !readSide.isAlive()) { |
| throw new IOException("Read end dead"); |
| } |
| } |
| |
| private void awaitSpace() throws IOException { |
| while (in == out) { |
| checkStateForReceive(); |
| |
| /* full: kick any waiting readers */ |
| notifyAll(); |
| try { |
| wait(1000); |
| } catch (InterruptedException ex) { |
| // Android-changed: re-set the thread's interrupt status |
| // throw new java.io.InterruptedIOException(); |
| IoUtils.throwInterruptedIoException(); |
| } |
| } |
| } |
| |
| /** |
| * Notifies all waiting threads that the last byte of data has been |
| * received. |
| */ |
| synchronized void receivedLast() { |
| closedByWriter = true; |
| notifyAll(); |
| } |
| |
| /** |
| * Reads the next byte of data from this piped input stream. The |
| * value byte is returned as an <code>int</code> in the range |
| * <code>0</code> to <code>255</code>. |
| * This method blocks until input data is available, the end of the |
| * stream is detected, or an exception is thrown. |
| * |
| * @return the next byte of data, or <code>-1</code> if the end of the |
| * stream is reached. |
| * @exception IOException if the pipe is |
| * {@link #connect(java.io.PipedOutputStream) unconnected}, |
| * <a href="#BROKEN"> <code>broken</code></a>, closed, |
| * or if an I/O error occurs. |
| */ |
| public synchronized int read() throws IOException { |
| if (!connected) { |
| throw new IOException("Pipe not connected"); |
| } else if (closedByReader) { |
| throw new IOException("Pipe closed"); |
| } else if (writeSide != null && !writeSide.isAlive() |
| && !closedByWriter && (in < 0)) { |
| throw new IOException("Write end dead"); |
| } |
| |
| readSide = Thread.currentThread(); |
| int trials = 2; |
| while (in < 0) { |
| if (closedByWriter) { |
| /* closed by writer, return EOF */ |
| return -1; |
| } |
| if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) { |
| throw new IOException("Pipe broken"); |
| } |
| /* might be a writer waiting */ |
| notifyAll(); |
| try { |
| wait(1000); |
| } catch (InterruptedException ex) { |
| // Android-changed: re-set the thread's interrupt status |
| // throw new java.io.InterruptedIOException(); |
| IoUtils.throwInterruptedIoException(); |
| } |
| } |
| int ret = buffer[out++] & 0xFF; |
| if (out >= buffer.length) { |
| out = 0; |
| } |
| if (in == out) { |
| /* now empty */ |
| in = -1; |
| } |
| |
| return ret; |
| } |
| |
| /** |
| * Reads up to <code>len</code> bytes of data from this piped input |
| * stream into an array of bytes. Less than <code>len</code> bytes |
| * will be read if the end of the data stream is reached or if |
| * <code>len</code> exceeds the pipe's buffer size. |
| * If <code>len </code> is zero, then no bytes are read and 0 is returned; |
| * otherwise, the method blocks until at least 1 byte of input is |
| * available, end of the stream has been detected, or an exception is |
| * thrown. |
| * |
| * @param b the buffer into which the data is read. |
| * @param off the start offset in the destination array <code>b</code> |
| * @param len the maximum number of bytes read. |
| * @return the total number of bytes read into the buffer, or |
| * <code>-1</code> if there is no more data because the end of |
| * the stream has been reached. |
| * @exception NullPointerException If <code>b</code> is <code>null</code>. |
| * @exception IndexOutOfBoundsException If <code>off</code> is negative, |
| * <code>len</code> is negative, or <code>len</code> is greater than |
| * <code>b.length - off</code> |
| * @exception IOException if the pipe is <a href="#BROKEN"> <code>broken</code></a>, |
| * {@link #connect(java.io.PipedOutputStream) unconnected}, |
| * closed, or if an I/O error occurs. |
| */ |
| public synchronized int read(byte b[], int off, int len) throws IOException { |
| if (b == null) { |
| throw new NullPointerException(); |
| } else if (off < 0 || len < 0 || len > b.length - off) { |
| throw new IndexOutOfBoundsException(); |
| } else if (len == 0) { |
| return 0; |
| } |
| |
| /* possibly wait on the first character */ |
| int c = read(); |
| if (c < 0) { |
| return -1; |
| } |
| b[off] = (byte) c; |
| int rlen = 1; |
| while ((in >= 0) && (len > 1)) { |
| |
| int available; |
| |
| if (in > out) { |
| available = Math.min((buffer.length - out), (in - out)); |
| } else { |
| available = buffer.length - out; |
| } |
| |
| // A byte is read beforehand outside the loop |
| if (available > (len - 1)) { |
| available = len - 1; |
| } |
| System.arraycopy(buffer, out, b, off + rlen, available); |
| out += available; |
| rlen += available; |
| len -= available; |
| |
| if (out >= buffer.length) { |
| out = 0; |
| } |
| if (in == out) { |
| /* now empty */ |
| in = -1; |
| } |
| } |
| return rlen; |
| } |
| |
| /** |
| * Returns the number of bytes that can be read from this input |
| * stream without blocking. |
| * |
| * @return the number of bytes that can be read from this input stream |
| * without blocking, or {@code 0} if this input stream has been |
| * closed by invoking its {@link #close()} method, or if the pipe |
| * is {@link #connect(java.io.PipedOutputStream) unconnected}, or |
| * <a href="#BROKEN"> <code>broken</code></a>. |
| * |
| * @exception IOException if an I/O error occurs. |
| * @since 1.0.2 |
| */ |
| public synchronized int available() throws IOException { |
| if(in < 0) |
| return 0; |
| else if(in == out) |
| return buffer.length; |
| else if (in > out) |
| return in - out; |
| else |
| return in + buffer.length - out; |
| } |
| |
| /** |
| * Closes this piped input stream and releases any system resources |
| * associated with the stream. |
| * |
| * @exception IOException if an I/O error occurs. |
| */ |
| public void close() throws IOException { |
| closedByReader = true; |
| synchronized (this) { |
| in = -1; |
| } |
| } |
| } |
