Re: [GENERAL] Notify argument?

Here is a patch that implements Tom's suggestion of mallocing the
relation name string as part of PQnotify and not depending on
NAMEDATALEN. Nice trick.

---------------------------------------------------------------------------

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > The breakage will come when we lengthen NAMEDATALEN, which I plan to
> > tackle for 7.3. We will need to re-order the NOTIFY structure and put
> > the NAMEDATALEN string at the end of the struct so differing namedatalen
> > backend/clients will work. If you want to break it, 7.3 would probably
> > be the time to do it. :-) Users will need a recompile pre-7.3 to use
> > notify for 7.3 and later anyway.
>
> If we're going to change the structure anyway, let's fix it to be
> independent of NAMEDATALEN. Instead of
>
> char relname[NAMEDATALEN];
> int be_pid;
>
> let's do
>
> char *relname;
> int be_pid;
>
> This should require no source-level changes in calling C code, thanks
> to C's equivalence between pointers and arrays. We can preserve the
> fact that freeing a PQnotifies result takes only one free() with a
> little hacking to make the string be allocated in the same malloc call:
>
> newNotify = (PGnotify *) malloc(sizeof(PGnotify) + strlen(str) + 1);
> newNotify->relname = (char *) newNotify + sizeof(PGnotify);
> strcpy(newNotify->relname, str);
>
> Thus, with one line of extra ugliness inside the library, we solve the
> problem permanently.
>
> regards, tom lane
>

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