Re: Import Statistics in postgres_fdw before resorting to sampling. - Mailing list pgsql-hackers

On Sun, Apr 12, 2026 at 11:15 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Coverity doesn't like this patch's uses of strncpy():
>
> >>>     CID 1691464:           (BUFFER_SIZE)
> >>>     Calling "strncpy" with a maximum size argument of 64 bytes on destination array
"remattrmap[attrcnt].local_attname"of size 64 bytes might leave the destination string unterminated. 
> 5960                    strncpy(remattrmap[attrcnt].local_attname, attname, NAMEDATALEN);
> 5961                    strncpy(remattrmap[attrcnt].remote_attname, remote_attname, NAMEDATALEN);
>
> I think it's dead right to complain: remote_attname, in particular,
> could certainly be longer than NAMEDATALEN.
>
> AFAICS, postgres_fdw's subsequent uses of those strings only need
> them to be nul-terminated C strings, so strncpy's property of
> zero-filling the whole buffer is not needed here.  I recommend
> s/strncpy/strlcpy/.

Seems like a good idea.

> It's probably also appropriate to think about using pg_mbcliplen()
> to ensure that this code doesn't result in a broken multibyte
> character.

Will do.

I am currently overseas and will be attending an event this week, so I
will work on this after returning home.  In the meantime, I created an
entry for it in the open items list.

Thanks!

Best regards,
Etsuro Fujita