Re: new module write-any-file

[Bruno Haible]

Paul Eggert wrote:
> >  And if priv_allocset succeeds, it will not cache the result,
> >  but instead redo the same system calls next time. Is this intentional?
> 
> I don't follow this point; it looks to me like it caches.

When priv_allocset is callable, the function looks like this:

bool
can_write_any_file (void)
{
  static bool initialized;
  static bool can;

  if (! initialized)
    {
      priv_set_t *pset = priv_allocset ();
      if (pset)
        {
          can =
            (getppriv (PRIV_EFFECTIVE, pset) == 0
             && priv_ismember (pset, PRIV_FILE_DAC_WRITE));
          priv_freeset (pset);
        }
      else
        initialized = true;
    }

  return can;
}

So if priv_allocset () succeeds, the 'initialized' variable stays false all
the time, and every invocation calls priv_allocset, getppriv, priv_ismember,
and priv_freeset again.

> Perhaps it's the "else #else" which confused you?  (It certainly confuses
> me...)

If it confuses even you, then it's late time to make this code more
readable! To follow Jim's habit of "no #ifs inside a function", you can for
example put the core of this function into a 'static inline' function
called 'can_write_any_file_uncached'.

Bruno