11544 ofmt(3OFMT) should talk about the callback handler
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Jason King <jason.brian.king@gmail.com>

*** 86,97 ****
  
       of_cb is the application-specified callback function with the following
       prototype that provides a string representation of the value to be
       printed for the field:
  
!            (*of_cb)(ofmt_arg_t *ofmt_arg, char *buf, uint_t bufsize)
  
       The interpretation of the of_id field is completely private to the
       caller, and can be optionally used by the callback function as a cookie
       to identify the field being printed when a single callback function is
       shared between multiple template entries.
  
--- 86,102 ----
  
       of_cb is the application-specified callback function with the following
       prototype that provides a string representation of the value to be
       printed for the field:
  
!            boolean_t (*of_cb)(ofmt_arg_t *ofmt_arg, char *buf, uint_t bufsize)
  
+      The callback must not write beyond bufsize bytes of the string form into
+      buf.  If the function successfully translates the field into its string
+      representation and places it into buf, then the callback function should
+      return B_TRUE.  Otherwise, the callback function should return B_FALSE.
+ 
       The interpretation of the of_id field is completely private to the
       caller, and can be optionally used by the callback function as a cookie
       to identify the field being printed when a single callback function is
       shared between multiple template entries.
  
*** 160,165 ****
       Private.
  
  SEE ALSO
       ioctl(2), strerror(3C), attributes(5)
  
! illumos                          June 1, 2017                          illumos
--- 165,170 ----
       Private.
  
  SEE ALSO
       ioctl(2), strerror(3C), attributes(5)
  
! illumos                        December 20, 2018                       illumos