/*
* 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;
import org.apache.harmony.luni.util.Msg;
// BEGIN android-added
import java.util.logging.Logger;
// END android-added
/**
* 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} on the {@link InputStream}
* {@code in}. The default buffer size (8 KB) is allocated and all reads
* can now be filtered through this stream.
*
* @param in
* the InputStream the buffer reads from.
*/
public BufferedInputStream(InputStream in) {
super(in);
buf = new byte[8192];
// BEGIN android-added
/*
* For Android, we want to discourage the use of this constructor (with
* its arguably too-large default), so we note its use in the log. We
* don't disable it, nor do we alter the default, however, because we
* still aim to behave compatibly, and the default value, though not
* documented, is established by convention.
*/
Logger.global.info(
"Default buffer size used in BufferedInputStream " +
"constructor. It would be " +
"better to be explicit if an 8k buffer is required.");
// END android-added
}
/**
* Constructs a new {@code BufferedInputStream} on the {@link InputStream}
* {@code in}. The buffer size is specified by the parameter {@code size}
* and all reads are now filtered through this stream.
*
* @param in
* the input stream the buffer reads from.
* @param size
* the size of buffer to allocate.
* @throws IllegalArgumentException
* if {@code size < 0}.
*/
public BufferedInputStream(InputStream in, int size) {
super(in);
if (size <= 0) {
// K0058=size must be > 0
throw new IllegalArgumentException(Msg.getString("K0058")); //$NON-NLS-1$
}
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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
return count - pos + localIn.available();
}
/**
* 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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
/* 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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
}
/* 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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
// 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(Msg.getString("K0047")); //$NON-NLS-1$
}
if ((offset | length) < 0 || offset > buffer.length - length) {
throw new IndexOutOfBoundsException(Msg.getString("K002f")); //$NON-NLS-1$
}
// END android-changed
if (length == 0) {
return 0;
}
InputStream localIn = in;
if (localIn == null) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
}
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) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
if (amount < 1) {
return 0;
}
if (localIn == null) {
// K0059=Stream is closed
throw new IOException(Msg.getString("K0059")); //$NON-NLS-1$
}
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);
}
}