| /* |
| * 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 java.io; |
| |
| /** |
| * Wraps an existing {@link InputStream} and <em>buffers</em> the input. |
| * Expensive interaction with the underlying input stream is minimized, since |
| * most (smaller) requests can be satisfied by accessing the buffer alone. The |
| * drawback is that some extra space is required to hold the buffer and that |
| * copying takes place when filling that buffer, but this is usually outweighed |
| * by the performance benefits. |
| * |
| * <p/>A typical application pattern for the class looks like this:<p/> |
| * |
| * <pre> |
| * BufferedInputStream buf = new BufferedInputStream(new FileInputStream("file.java")); |
| * </pre> |
| * |
| * @see BufferedOutputStream |
| */ |
| public class BufferedInputStream extends FilterInputStream { |
| /** |
| * The buffer containing the current bytes read from the target InputStream. |
| */ |
| protected volatile byte[] buf; |
| |
| /** |
| * The total number of bytes inside the byte array {@code buf}. |
| */ |
| protected int count; |
| |
| /** |
| * The current limit, which when passed, invalidates the current mark. |
| */ |
| protected int marklimit; |
| |
| /** |
| * The currently marked position. -1 indicates no mark has been set or the |
| * mark has been invalidated. |
| */ |
| protected int markpos = -1; |
| |
| /** |
| * The current position within the byte array {@code buf}. |
| */ |
| protected int pos; |
| |
| /** |
| * Constructs a new {@code BufferedInputStream}, providing {@code in} with a buffer |
| * of 8192 bytes. |
| * |
| * <p><strong>Warning:</strong> passing a null source creates a closed |
| * {@code BufferedInputStream}. All read operations on such a stream will |
| * fail with an IOException. |
| * |
| * @param in the {@code InputStream} the buffer reads from. |
| */ |
| public BufferedInputStream(InputStream in) { |
| this(in, 8192); |
| } |
| |
| /** |
| * Constructs a new {@code BufferedInputStream}, providing {@code in} with {@code size} bytes |
| * of buffer. |
| * |
| * <p><strong>Warning:</strong> passing a null source creates a closed |
| * {@code BufferedInputStream}. All read operations on such a stream will |
| * fail with an IOException. |
| * |
| * @param in the {@code InputStream} the buffer reads from. |
| * @param size the size of buffer in bytes. |
| * @throws IllegalArgumentException if {@code size <= 0}. |
| */ |
| public BufferedInputStream(InputStream in, int size) { |
| super(in); |
| if (size <= 0) { |
| throw new IllegalArgumentException("size <= 0"); |
| } |
| buf = new byte[size]; |
| } |
| |
| /** |
| * Returns an estimated number of bytes that can be read or skipped without blocking for more |
| * input. This method returns the number of bytes available in the buffer |
| * plus those available in the source stream, but see {@link InputStream#available} for |
| * important caveats. |
| * |
| * @return the estimated number of bytes available |
| * @throws IOException if this stream is closed or an error occurs |
| */ |
| @Override |
| public synchronized int available() throws IOException { |
| InputStream localIn = in; // 'in' could be invalidated by close() |
| if (buf == null || localIn == null) { |
| throw streamClosed(); |
| } |
| return count - pos + localIn.available(); |
| } |
| |
| private IOException streamClosed() throws IOException { |
| throw new IOException("BufferedInputStream is closed"); |
| } |
| |
| /** |
| * Closes this stream. The source stream is closed and any resources |
| * associated with it are released. |
| * |
| * @throws IOException |
| * if an error occurs while closing this stream. |
| */ |
| @Override |
| public void close() throws IOException { |
| buf = null; |
| InputStream localIn = in; |
| in = null; |
| if (localIn != null) { |
| localIn.close(); |
| } |
| } |
| |
| private int fillbuf(InputStream localIn, byte[] localBuf) |
| throws IOException { |
| if (markpos == -1 || (pos - markpos >= marklimit)) { |
| /* Mark position not set or exceeded readlimit */ |
| int result = localIn.read(localBuf); |
| if (result > 0) { |
| markpos = -1; |
| pos = 0; |
| count = result == -1 ? 0 : result; |
| } |
| return result; |
| } |
| if (markpos == 0 && marklimit > localBuf.length) { |
| /* Increase buffer size to accommodate the readlimit */ |
| int newLength = localBuf.length * 2; |
| if (newLength > marklimit) { |
| newLength = marklimit; |
| } |
| byte[] newbuf = new byte[newLength]; |
| System.arraycopy(localBuf, 0, newbuf, 0, localBuf.length); |
| // Reassign buf, which will invalidate any local references |
| // FIXME: what if buf was null? |
| localBuf = buf = newbuf; |
| } else if (markpos > 0) { |
| System.arraycopy(localBuf, markpos, localBuf, 0, localBuf.length |
| - markpos); |
| } |
| /* Set the new position and mark position */ |
| pos -= markpos; |
| count = markpos = 0; |
| int bytesread = localIn.read(localBuf, pos, localBuf.length - pos); |
| count = bytesread <= 0 ? pos : pos + bytesread; |
| return bytesread; |
| } |
| |
| /** |
| * Sets a mark position in this stream. The parameter {@code readlimit} |
| * indicates how many bytes can be read before a mark is invalidated. |
| * Calling {@code reset()} will reposition the stream back to the marked |
| * position if {@code readlimit} has not been surpassed. The underlying |
| * buffer may be increased in size to allow {@code readlimit} number of |
| * bytes to be supported. |
| * |
| * @param readlimit |
| * the number of bytes that can be read before the mark is |
| * invalidated. |
| * @see #reset() |
| */ |
| @Override |
| public synchronized void mark(int readlimit) { |
| marklimit = readlimit; |
| markpos = pos; |
| } |
| |
| /** |
| * Indicates whether {@code BufferedInputStream} supports the {@code mark()} |
| * and {@code reset()} methods. |
| * |
| * @return {@code true} for BufferedInputStreams. |
| * @see #mark(int) |
| * @see #reset() |
| */ |
| @Override |
| public boolean markSupported() { |
| return true; |
| } |
| |
| /** |
| * Reads a single byte from this stream and returns it as an integer in the |
| * range from 0 to 255. Returns -1 if the end of the source string has been |
| * reached. If the internal buffer does not contain any available bytes then |
| * it is filled from the source stream and the first byte is returned. |
| * |
| * @return the byte read or -1 if the end of the source stream has been |
| * reached. |
| * @throws IOException |
| * if this stream is closed or another IOException occurs. |
| */ |
| @Override |
| public synchronized int read() throws IOException { |
| // Use local refs since buf and in may be invalidated by an |
| // unsynchronized close() |
| byte[] localBuf = buf; |
| InputStream localIn = in; |
| if (localBuf == null || localIn == null) { |
| throw streamClosed(); |
| } |
| |
| /* Are there buffered bytes available? */ |
| if (pos >= count && fillbuf(localIn, localBuf) == -1) { |
| return -1; /* no, fill buffer */ |
| } |
| // localBuf may have been invalidated by fillbuf |
| if (localBuf != buf) { |
| localBuf = buf; |
| if (localBuf == null) { |
| throw streamClosed(); |
| } |
| } |
| |
| /* Did filling the buffer fail with -1 (EOF)? */ |
| if (count - pos > 0) { |
| return localBuf[pos++] & 0xFF; |
| } |
| return -1; |
| } |
| |
| /** |
| * Reads at most {@code length} bytes from this stream and stores them in |
| * byte array {@code buffer} starting at offset {@code offset}. Returns the |
| * number of bytes actually read or -1 if no bytes were read and the end of |
| * the stream was encountered. If all the buffered bytes have been used, a |
| * mark has not been set and the requested number of bytes is larger than |
| * the receiver's buffer size, this implementation bypasses the buffer and |
| * simply places the results directly into {@code buffer}. |
| * |
| * @param buffer |
| * the byte array in which to store the bytes read. |
| * @param offset |
| * the initial position in {@code buffer} to store the bytes read |
| * from this stream. |
| * @param length |
| * the maximum number of bytes to store in {@code buffer}. |
| * @return the number of bytes actually read or -1 if end of stream. |
| * @throws IndexOutOfBoundsException |
| * if {@code offset < 0} or {@code length < 0}, or if |
| * {@code offset + length} is greater than the size of |
| * {@code buffer}. |
| * @throws IOException |
| * if the stream is already closed or another IOException |
| * occurs. |
| */ |
| @Override |
| public synchronized int read(byte[] buffer, int offset, int length) throws IOException { |
| // Use local ref since buf may be invalidated by an unsynchronized |
| // close() |
| byte[] localBuf = buf; |
| if (localBuf == null) { |
| throw streamClosed(); |
| } |
| // avoid int overflow |
| // BEGIN android-changed |
| // Exception priorities (in case of multiple errors) differ from |
| // RI, but are spec-compliant. |
| // made implicit null check explicit, used (offset | length) < 0 |
| // instead of (offset < 0) || (length < 0) to safe one operation |
| if (buffer == null) { |
| throw new NullPointerException("buffer == null"); |
| } |
| if ((offset | length) < 0 || offset > buffer.length - length) { |
| throw new IndexOutOfBoundsException(); |
| } |
| // END android-changed |
| if (length == 0) { |
| return 0; |
| } |
| InputStream localIn = in; |
| if (localIn == null) { |
| throw streamClosed(); |
| } |
| |
| int required; |
| if (pos < count) { |
| /* There are bytes available in the buffer. */ |
| int copylength = count - pos >= length ? length : count - pos; |
| System.arraycopy(localBuf, pos, buffer, offset, copylength); |
| pos += copylength; |
| if (copylength == length || localIn.available() == 0) { |
| return copylength; |
| } |
| offset += copylength; |
| required = length - copylength; |
| } else { |
| required = length; |
| } |
| |
| while (true) { |
| int read; |
| /* |
| * If we're not marked and the required size is greater than the |
| * buffer, simply read the bytes directly bypassing the buffer. |
| */ |
| if (markpos == -1 && required >= localBuf.length) { |
| read = localIn.read(buffer, offset, required); |
| if (read == -1) { |
| return required == length ? -1 : length - required; |
| } |
| } else { |
| if (fillbuf(localIn, localBuf) == -1) { |
| return required == length ? -1 : length - required; |
| } |
| // localBuf may have been invalidated by fillbuf |
| if (localBuf != buf) { |
| localBuf = buf; |
| if (localBuf == null) { |
| throw streamClosed(); |
| } |
| } |
| |
| read = count - pos >= required ? required : count - pos; |
| System.arraycopy(localBuf, pos, buffer, offset, read); |
| pos += read; |
| } |
| required -= read; |
| if (required == 0) { |
| return length; |
| } |
| if (localIn.available() == 0) { |
| return length - required; |
| } |
| offset += read; |
| } |
| } |
| |
| /** |
| * Resets this stream to the last marked location. |
| * |
| * @throws IOException |
| * if this stream is closed, no mark has been set or the mark is |
| * no longer valid because more than {@code readlimit} bytes |
| * have been read since setting the mark. |
| * @see #mark(int) |
| */ |
| @Override |
| public synchronized void reset() throws IOException { |
| // BEGIN android-changed |
| /* |
| * These exceptions get thrown in some "normalish" circumstances, |
| * so it is preferable to avoid loading up the whole big set of |
| * messages just for these cases. |
| */ |
| if (buf == null) { |
| throw new IOException("Stream is closed"); |
| } |
| if (-1 == markpos) { |
| throw new IOException("Mark has been invalidated."); |
| } |
| // END android-changed |
| pos = markpos; |
| } |
| |
| /** |
| * Skips {@code amount} number of bytes in this stream. Subsequent |
| * {@code read()}'s will not return these bytes unless {@code reset()} is |
| * used. |
| * |
| * @param amount |
| * the number of bytes to skip. {@code skip} does nothing and |
| * returns 0 if {@code amount} is less than zero. |
| * @return the number of bytes actually skipped. |
| * @throws IOException |
| * if this stream is closed or another IOException occurs. |
| */ |
| @Override |
| public synchronized long skip(long amount) throws IOException { |
| // Use local refs since buf and in may be invalidated by an |
| // unsynchronized close() |
| byte[] localBuf = buf; |
| InputStream localIn = in; |
| if (localBuf == null) { |
| throw streamClosed(); |
| } |
| if (amount < 1) { |
| return 0; |
| } |
| if (localIn == null) { |
| throw streamClosed(); |
| } |
| |
| if (count - pos >= amount) { |
| pos += amount; |
| return amount; |
| } |
| long read = count - pos; |
| pos = count; |
| |
| if (markpos != -1) { |
| if (amount <= marklimit) { |
| if (fillbuf(localIn, localBuf) == -1) { |
| return read; |
| } |
| if (count - pos >= amount - read) { |
| pos += amount - read; |
| return amount; |
| } |
| // Couldn't get all the bytes, skip what we read |
| read += (count - pos); |
| pos = count; |
| return read; |
| } |
| } |
| return read + localIn.skip(amount - read); |
| } |
| } |
