[CFR] reflect resolv.conf update to running application

[Sergey Babkin]

>In the last episode (Aug 23), Peter Jeremy said:
>> On Mon, 2005-Aug-22 13:18:46 -0700, Matthew Reimer wrote:
>> >How about just stat'ing resolv.conf if more than X seconds has
>> >passed since the last stat, rather than for every lookup?
>> 
>> That reduces the number of stat() calls but doesn't resolve the
>> possibility of reading a half-written resolv.conf.
>
>Easy enough to only reread the file if stat tells you it's more than 2
>seconds old.

Won't reliably help: the file might change after you've done stat. The real solution would be to :

* do stat, see that the file has changed 
* read the file into an intermediate buffer
* wait 1 or 2 seconds
* do stat again, if the time has not 
changed since the first stat then the 
contents of your buffer is valid and 
yu can use it

-SB