Re: gethostname max len

[Wolfgang Jaehrling]

On Mon, Mar 22, 2004 at 08:22:52AM +1000, Kevin Ryde wrote:
>         * posix.c (scm_gethostname): Use sysconf(_SC_HOST_NAME_MAX) and
>         MAXHOSTNAMELEN when available.
> 
> It's possible MAXHOSTNAMELEN is enough in practice, but posix
> specifies HOST_NAME_MAX instead of MAXHOSTNAMELEN, so it seems
> worthwhile checking that too.

The Single Unix Specification says about sysconf():

  "If name is an invalid value, sysconf() shall return -1 and set
  errno to indicate the error. If the variable corresponding to name
  has no limit, sysconf() shall return -1 without changing the value
  of errno."

And in the following informative section:

  "As -1 is a permissible return value in a successful situation, an
  application wishing to check for error situations should set errno
  to 0, then call sysconf(), and, if it returns -1, check to see if
  errno is non-zero."

Which is what Guile probably also should do, otherwise it won't work
correctly on the GNU system, which has no limit on the length of host
names; the current code that checks for ENAMETOOLONG looks quite
GNU/Linux-specific.

Cheers,
Wolfgang

-- 
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