How can I read Extended APDU input to the same buffer

Question

The following is the code I am currently using where inBuffer is an intermediate array of 1000 length. However, I do not want to allocate any buffers at all, and just want to send a command apdu of 1000 byte length and modify it in the code and return the modified buf in the response APDU.
// Read extended APDU input
byte[] buf = apdu.getBuffer();
short bytesRead = apdu.setIncomingAndReceive();
short dataOffset = apdu.getOffsetCdata();
// store first chunk in our intermediate byte array <-- how do i get rid of the intermediate array
Util.arrayCopyNonAtomic(buf, dataOffset, inBuffer, (short) 0, bytesRead);
// what is the overall length?
short overallLength = apdu.getIncomingLength();
short messageOffset = bytesRead;
if (bytesRead != overallLength){ // otherwise we're finished, all bytes received
     short received = 0;
     do{
               received = apdu.receiveBytes((short)0);
               Util.arrayCopyNonAtomic(buf, (short)0, inBuffer, messageOffset, received);
               messageOffset  += received;
          } while(received != 0);
* REST OF CODE IN PROCESS METHOD
I have also tried replacing the above code with the following
short bytesLeft = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
if (bytesLeft < (short)55) ISOException.throwIt( ISO7816.SW_WRONG_LENGTH );
short readCount = apdu.setIncomingAndReceive();
while ( bytesLeft > 0){
  // process bytes in buffer[5] to buffer[readCount+4];
  bytesLeft -= readCount;
  readCount = apdu.receiveBytes ( ISO7816.OFFSET_CDATA );
as shown in the javadocs API, but it does not compile.
This is my command APDU:
/send 800100000003E8000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003E8
As you can see:
CLA - 80
INS - 01
P1 & P2 - 00
LC - 0003E8
Data - 1000 0s
LE - 03E8
I am using JavaCard 3.0 with JCOP in Eclipse. How can I read the extended length apdu to the same buffer? I have no problem in returning an extended length response APDU. Thanks a lot for the help.

Answer 1

You should not call the convenience method setIncomingAndReceive() in your first code. Please find out about the different APDU states. Furthermore, your Applet should implement the ExtendedLength tagging interface.