private ByteList bufferedRead(int number) throws IOException, BadDescriptorException {
checkReadable();
ensureRead();
int resultSize = 0;
// 128K seems to be the minimum at which the stat+seek is faster than reallocation
final int BULK_THRESHOLD = 128 * 1024;
if (number >= BULK_THRESHOLD
&& descriptor.isSeekable()
&& descriptor.getChannel() instanceof FileChannel) {
//
// If it is a file channel, then we can pre-allocate the output buffer
// to the total size of buffered + remaining bytes in file
//
FileChannel fileChannel = (FileChannel) descriptor.getChannel();
resultSize =
(int)
Math.min(
fileChannel.size() - fileChannel.position() + bufferedInputBytesRemaining(),
number);
} else {
//
// Cannot discern the total read length - allocate at least enough for the buffered data
//
resultSize = Math.min(bufferedInputBytesRemaining(), number);
}
ByteList result = new ByteList(resultSize);
bufferedRead(result, number);
return result;
}
private void resetForWrite() throws IOException {
if (descriptor.isSeekable()) {
FileChannel fileChannel = (FileChannel) descriptor.getChannel();
if (buffer.hasRemaining()) { // we have read ahead, and need to back up
fileChannel.position(fileChannel.position() - buffer.remaining());
}
}
// FIXME: Clearing read buffer here...is this appropriate?
buffer.clear();
reading = false;
}
/** @throws IOException */
public synchronized long fgetpos()
throws IOException, PipeException, InvalidValueException, BadDescriptorException {
// Correct position for read / write buffering (we could invalidate, but expensive)
if (descriptor.isSeekable()) {
FileChannel fileChannel = (FileChannel) descriptor.getChannel();
long pos = fileChannel.position();
// Adjust for buffered data
if (reading) {
pos -= buffer.remaining();
return pos - (pos > 0 && ungotc != -1 ? 1 : 0);
} else {
return pos + buffer.position();
}
} else if (descriptor.isNull()) {
return 0;
} else {
throw new PipeException();
}
}
/**
* Implementation of libc "lseek", which seeks on seekable streams, raises EPIPE if the fd is
* assocated with a pipe, socket, or FIFO, and doesn't do anything for other cases (like stdio).
*
* @throws IOException
* @throws InvalidValueException
*/
public synchronized void lseek(long offset, int type)
throws IOException, InvalidValueException, PipeException, BadDescriptorException {
if (descriptor.isSeekable()) {
FileChannel fileChannel = (FileChannel) descriptor.getChannel();
ungotc = -1;
int adj = 0;
if (reading) {
// for SEEK_CUR, need to adjust for buffered data
adj = buffer.remaining();
buffer.clear();
buffer.flip();
} else {
flushWrite();
}
try {
switch (type) {
case SEEK_SET:
fileChannel.position(offset);
break;
case SEEK_CUR:
fileChannel.position(fileChannel.position() - adj + offset);
break;
case SEEK_END:
fileChannel.position(fileChannel.size() + offset);
break;
}
} catch (IllegalArgumentException e) {
throw new InvalidValueException();
} catch (IOException ioe) {
throw ioe;
}
} else if (descriptor.getChannel() instanceof SelectableChannel) {
// TODO: It's perhaps just a coincidence that all the channels for
// which we should raise are instanceof SelectableChannel, since
// stdio is not...so this bothers me slightly. -CON
throw new PipeException();
} else {
}
}
/**
* @deprecated readall do busy loop for the IO which has NONBLOCK bit. You should implement the
* logic by yourself with fread().
*/
@Deprecated
public synchronized ByteList readall() throws IOException, BadDescriptorException {
final long fileSize =
descriptor.isSeekable() && descriptor.getChannel() instanceof FileChannel
? ((FileChannel) descriptor.getChannel()).size()
: 0;
//
// Check file size - special files in /proc have zero size and need to be
// handled by the generic read path.
//
if (fileSize > 0) {
ensureRead();
FileChannel channel = (FileChannel) descriptor.getChannel();
final long left = fileSize - channel.position() + bufferedInputBytesRemaining();
if (left <= 0) {
eof = true;
return null;
}
if (left > Integer.MAX_VALUE) {
if (getRuntime() != null) {
throw getRuntime().newIOError("File too large");
} else {
throw new IOException("File too large");
}
}
ByteList result = new ByteList((int) left);
ByteBuffer buf = ByteBuffer.wrap(result.getUnsafeBytes(), result.begin(), (int) left);
//
// Copy any buffered data (including ungetc byte)
//
copyBufferedBytes(buf);
//
// Now read unbuffered directly from the file
//
while (buf.hasRemaining()) {
final int MAX_READ_CHUNK = 1 * 1024 * 1024;
//
// When reading into a heap buffer, the jvm allocates a temporary
// direct ByteBuffer of the requested size. To avoid allocating
// a huge direct buffer when doing ludicrous reads (e.g. 1G or more)
// we split the read up into chunks of no more than 1M
//
ByteBuffer tmp = buf.duplicate();
if (tmp.remaining() > MAX_READ_CHUNK) {
tmp.limit(tmp.position() + MAX_READ_CHUNK);
}
int n = channel.read(tmp);
if (n <= 0) {
break;
}
buf.position(tmp.position());
}
eof = true;
result.length(buf.position());
return result;
} else if (descriptor.isNull()) {
return new ByteList(0);
} else {
checkReadable();
ByteList byteList = new ByteList();
ByteList read = fread(BUFSIZE);
if (read == null) {
eof = true;
return byteList;
}
while (read != null) {
byteList.append(read);
read = fread(BUFSIZE);
}
return byteList;
}
}
