Re: pg_ctl/miscinit: print "MyStartTime" as a long long instead of long to avoid 2038 problem. - Mailing list pgsql-hackers

On Tue, Sep 24, 2024 at 07:33:24PM +0000, Max Johnson wrote:
> I have found an instance of a time overflow with the start time that is
> written in "postmaster.pid". On a 32-bit Linux system, if the system date
> is past 01/19/2038, when you start Postgres with `pg_ctl start -D
> {datadir} ...`,  the start time will have rolled back to approximately
> 1900. This is an instance of the "2038 problem". On my system, pg_ctl
> will not exit if the start time has overflowed.

Nice find.  I think this has been the case since the start time was added
to the lock files [0].

> -    snprintf(buffer, sizeof(buffer), "%d\n%s\n%ld\n%d\n%s\n",
> +    snprintf(buffer, sizeof(buffer), "%d\n%s\n%lld\n%d\n%s\n",
>               amPostmaster ? (int) my_pid : -((int) my_pid),
>               DataDir,
> -             (long) MyStartTime,
> +             (long long) MyStartTime,
>               PostPortNumber,
>               socketDir);

I think we should use INT64_FORMAT here.  That'll choose the right length
modifier for the platform.  And I don't think we need to cast MyStartTime,
since it's a pg_time_t (which is just an int64).

[0] https://postgr.es/c/30aeda4

-- 
nathan