On Fri, Jan 14, 2005 at 12:06:32PM -0500, Tom Lane wrote:
> strk <[EMAIL PROTECTED]> writes:
> > A simple patch allow query output in psql PROMPT strings:
> 
> Why is this a good idea?  Having a query implicitly executed during
> every prompt will have a ton of bad side effects, for instance
> prematurely freezing the query snapshot in SERIALIZABLE transactions.

The only purpose for having made the patch is having current_schema()
printed on the prompt (for the first question).

I know the code is very dirty, is there a chance to current_schema()
as a variable if that won't change transaction status ?

--strk;

> 
> The syntax you propose is downright bizarre --- what if I needed a dot
> in the query text?
> 
> > +                                           cmdend = strcspn(cmd, ".");
> > +                                           cmd[cmdend] = '\0';
> > +                                           if (cmd)
> > +                                           {
> > +                                                   res = PSQLexec(cmd, 
> > false);
> > +                                           }
> 
> What's the if for?  cmd can't be NULL (you already dumped core if it
> is).
> 
> > +                                           if (res && PQntuples(res) )
> > +                                           {
> > +                                                   memcpy(buf, 
> > PQgetvalue(res, 0, 0), MAX_PROMPT_SIZE-1);
> > +                                                   PQclear(res);
> > +                                           }
> 
> Leaks memory on query failure.
> 
> > +                                           if (strlen(buf) > 0 && 
> > buf[strlen(buf) - 1] == '\n')
> > +                                                   buf[strlen(buf) - 1] = 
> > '\0';
> 
> Uses undefined contents of buf on query failure.
> 
> > +                                           p += cmdend + 1;
> 
> Falls off the end of the prompt if there was no terminating dot, causing
> subsequent iterations of the loop to continue reading undefined memory.
> 
>                       regards, tom lane

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