Takatoshi Kondo 3bd0172a9a Unified NULL buf handling for all *buffer.
*buffer means sbuffer, zbuffer, fbuffer, and vrefbuffer.

The logic is as follows:

if buf is NULL
   if len is 0
      do nothing return 0 (success)
   else
      assertion fail
else
   set contants to *buffer
2020-07-03 09:18:00 +09:00
..
2015-11-21 12:41:46 +09:00