[9fans] return of fd2path

[William Ahern <william@wilbur.25thandclement.com>]

i writing a little program which needs to keep track of paths to open file
descriptors [on *bsd/linux]. i wrote a lexical path normalizer, which
is almost exactly the same as cleanname(), but i only figured that out
afterwards (and after i found SUSv3's realpath() ;).

anyhow, i also found fd2path(). so i'm in the process of shuffling my code
to mimic the semantics of cleanname() and fd2path(), just 'cause i like
their simplicity and might as well work toward an existing interface.

_anyhow_, one thing that bugs me is the return value of fd2path().
why not make the return value similar to SUSv3's snprintf()? that is, return
the length of the logical string? i saw a few posts on this. one was to make
the return value the remainder of the logical length and the buffer length.
another pointed out that inferno just returned a malloc'd string on its own.

but, why force the developer to continually use strlen()? in my application
i am keeping track of the length of the file paths from the instance the
strings enter the program. i try to use only string functions that force
superfluous use strlen(). the semantics of snprintf() seem quite reasonable.
in fact, i can't really figure out a down side... anybody?

i'm not trying to micro-optomize here, but in this case it doesn't make any
sense to continually re-calculate the length of a string.

curious....

- Bill