Re: [HACKERS] Re: [HACKERS] Re: [HACKERS] Re: [HACKERS] Windows service is not starting so there’s message in log: FATAL: "could not create shared memory segment “Global/PostgreSQL.851401618”: Permission denied”

On Fri, Sep 23, 2016 at 1:21 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Tue, Sep 20, 2016 at 12:53 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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.
>

Isn't it better if we use the same technique in dsm_create() as well
which uses random() for handle?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com