Re: [PATCH] Fix buffer not null terminated on (ecpg lib)

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От Ranier Vilela
Тема Re: [PATCH] Fix buffer not null terminated on (ecpg lib)
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Msg-id CAEudQApqcJpAsbhsHM6FOwVxUsKNV=X8WxBpr10ipB-acEpwWw@mail.gmail.com
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Ответ на Re: [PATCH] Fix buffer not null terminated on (ecpg lib)  (Andres Freund <andres@anarazel.de>)
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Em ter., 15 de jun. de 2021 às 15:48, Andres Freund <andres@anarazel.de> escreveu:
Hi,

On 2021-06-15 13:53:08 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2021-06-15 07:40:46 -0300, Ranier Vilela wrote:
> >> memcpy would not suffer from it?
>
> > It'd not be correct for short sqlstates - you'd read beyond the end of
> > the source buffer. There are cases of it in the ecpg code.
>
> What's a "short SQLSTATE"?  They're all five characters by definition.

I thought there were places that just dealt with "00" etc. And there are - but
it's just comparisons.

I still don't fully feel comfortable just using memcpy() though, given that
the sqlstates originate remotely / from libpq, making it hard to rely on the
fact that the buffer "ought to" always be at least 5 bytes long? As far as I
can tell there's no enforcement of PQresultErrorField(..., PG_DIAG_SQLSTATE)
being that long.
And replacing with snprintf, what do you guys think?

    n = snprintf(sqlca->sqlstate, sizeof(sqlca->sqlstate), "%s", sqlstate);
    Assert(n >= 0 && n < sizeof(sqlca->sqlstate));

regards,
Ranier Vilela
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