public synchronized void ftruncate(long newLength)
throws IOException, BadDescriptorException, InvalidValueException {
Channel ch = descriptor.getChannel();
if (!(ch instanceof FileChannel)) {
throw new InvalidValueException();
}
invalidateBuffer();
FileChannel fileChannel = (FileChannel) ch;
long position = fileChannel.position();
if (newLength > fileChannel.size()) {
// truncate can't lengthen files, so we save position, seek/write, and go back
int difference = (int) (newLength - fileChannel.size());
fileChannel.position(fileChannel.size());
// FIXME: This worries me a bit, since it could allocate a lot with a large newLength
fileChannel.write(ByteBuffer.allocate(difference));
} else {
fileChannel.truncate(newLength);
}
fileChannel.position(position);
}
