I think it probably is a good idea to supply a way to find the maximum
file name size on a file system.  For most programs it doesn't matter,
but programs that tack on a suffix would like to make sure that the
new name is really different from the old.  Otherwise foo~ or foo.Z
overwrite foo, This is an issue that SVr4 also has to deal with, since
they also have multiple file types, both sys5 -- with short names, and
ufs -- with long names.  Why not do it compatibly?  Implement statvfs.
One of the fields it returns is f_namemax, the maximum file name size
for the file system.