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From: Nate Williams <nate@mt.sri.com>
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To: "Louis A. Mamakos" <louie@TransSys.COM>
Cc: ognir@humboldt1.com, steve_tarkalson@hotmail.com,
	bmcgover@cisco.com, dan@trinsec.com, hackers@FreeBSD.ORG
Subject: Re: gethostbyaddr() and threads. 
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	<199908092322.TAA68246@whizzo.transsys.com>
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> > ---Steve Tarkalson said:
> > > this is solved by one of two methods:
> > >    1-) require the caller of gethostbyaddr() to supply a pointer to
> > >        a hostent struct which will be filled.
> > > or 2-) the library uses thread specific storage which is re-used in
> > >        each call.
> > > 
> > You could malloc() a struct hostent for each call to
> > gethostby*(), each time registering the hostent in some list along with the
> > thread's PID. If the same thread calls gethostby*, use the same buffer, or
> > allocate a new one if another thread calls it. Have a static function be called
> > atexit to free all the mallocs.
> 
> Yuk!
> 
> If you're writing a multithreaded program, a slightly different API for
> gethostbyname() is likely to be the least of your worries.

Agreed.  gethostbyname_r() on solaris requires the caller to provide the
address to write into, which is IMO the correct solution.

Yes, it's a different API.  But, the other alternatives are worse.  The
user must be able to control his memory allocation.

For example, in a typical networking application, gethostbyname() could
be called thousands or millions of times, and allocating memory
everytime that can't be cleaned up until the program exits is completely
unacceptable.


Nate


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