From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Amit Kapila <amit.kapila16@gmail.com>,
        Dmitry Vasilyev <d.vasilyev@postgrespro.ru>,
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 20 Sep 2016 13:05:03 -0400"
Date: Thu, 22 Sep 2016 15:51:36 -0400
Message-ID: <11822.1474573896@sss.pgh.pa.us>
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Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Sep 20, 2016 at 12:53 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'd be the first to agree that this point is inadequately documented
>> in the code, but PostmasterRandom should be reserved for its existing
>> security-related uses, not exposed to the world for (ahem) random other
>> uses.

> So, we could have dsm_postmaster_startup() seed the random number
> generator itself, and then let PostmasterRandom() override the seed
> later.  Like maybe:

Works for me, at least as a temporary solution.  The disturbing thing
here is that this still only does what we want if dsm_postmaster_startup
happens before the first PostmasterRandom call --- which is OK today but
seems pretty fragile.  Still, redesigning PostmasterRandom's seeding
technique is not something to do right before 9.6 release.  Let's revert
the prior patch and do it as you have here:

> struct timeval tv;
> gettimeofday(&tv, NULL);
> srandom(tv.tv_sec);
> ...
> dsm_control_handle = random();

for the time being.

			regards, tom lane


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