question: @ Override public int read ( byte [ ] b , int off , int len ) throws IOException { if ( closed ) { throw new FileUploadException ( ItemSkippedException ) ; } if ( len == 0 ) { return 0 ; } int res = available ( ) ; if ( res == 0 ) { res = makeAvailable ( ) ; if ( res == 0 ) { return - 1 ; } } res = Math . min ( res , len ) ; System . arraycopy ( buffer , head , b , off , res ) ; head += res ; total += res ; return res ; }
target:  Reads bytes into the given buffer.