saved_errno

[Jeremy Allison]

Andrew Tridgell wrote:
> 
> Jeremy,
> 
> What is the logic behind saved_errno in filename.c??
> 
> To me it seems totally spurious, and if you set "case sensitive = yes"
> then the saved_errno code slows down directory reads by a factor of
> about 20 in tests I've done (test with 10000 files took 400 seconds
> with code as is and 20 seconds after removing the saved_errno test in
> unix_convert())
> 
> I don't see what else saved_errno will be set to other than ENOENT and
> I don't see why we should do the search just because it was a
> ENOENT.
> 
> I'll take the test out for the moment - I'm sure it's not correct.

Actually, saved_errno as a variable wasn't needed (it was paranoid code
as I was assuming the debug statement might trash errno), however
the test itself seemed useful and was meant as an optimisation
(although I might have got the logic swapped...).

The original code went :

  if (dos_stat(name,&st) == 0) {
       ...found name...
  }

  /*
   * A special case - if we don't have any mangling chars and are case
   * sensitive then searching won't help.
   */

  if (case_sensitive && !is_mangled(name) &&
      !lp_strip_dot() && !use_mangled_map && (saved_errno != ENOENT))
    return(False);

Ah - now I see the problem. I got the logic on the test wrong
on the case sensitive test. What I *should* have written was

  if (case_sensitive && !is_mangled(name) &&
      !lp_strip_dot() && !use_mangled_map && (saved_errno == ENOENT))
    return(False);

Note the != to == change. Rats :-(. Of course the test
itself was totally bogus anyway, as even if the error was
other than ENOENT we should have been returning at that
point anyway !

Sorry, logic bug. I'll commit it to the release tree.

Jeremy.


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