RES  SIZE FILE
 512K  512K ddtest

whole file
status: 0
RES  SIZE FILE
 0B  512K ddtest

offset: 131072
status: 0
  RES  SIZE FILE
 128K  512K ddtest

length: 262144
status: 0
  RES  SIZE FILE
 256K  512K ddtest

offset: 131072, length: 262144 fd: 42
status: 0
  RES  SIZE FILE
 256K  512K ddtest