Re: Small memory fixes for pg_createsubcriber

Hi,

On 2025-02-11 13:32:32 -0300, Euler Taveira wrote:
> On Mon, Feb 10, 2025, at 1:31 PM, Ranier Vilela wrote:
> > Coverity has some reports about pg_createsubcriber.
> >
> > CID 1591322: (#1 of 1): Resource leak (RESOURCE_LEAK)
> > 10. leaked_storage: Variable dbname going out of scope leaks the storage it points to.
> > Additionally there are several calls that are out of the ordinary, according to the Postgres API.
> >
> > According to the documentation:
> > libpq-exec <https://www.postgresql.org/docs/current/libpq-exec.html>
> >
> >
> > The correct function to free memory when using PQescapeLiteral and PQescapeIdentifier would be PQfreemem.
> >
>
> Hi,
>
> From src/common/fe_memutils.c:
>
> void
> pg_free(void *ptr)
> {
> free(ptr);
> }
>
> From src/interfaces/libpq/fe-exec.c:
>
> void
> PQfreemem(void *ptr)
> {
> free(ptr);
> }
>
> There is no bug. They are the same behind the scenes. I'm fine changing it. It
> is a new code and it wouldn't cause a lot of pain to backpatch patches in the
> future.

That *is* a bug. On windows the allocator that a shared library (i.e. libpq)
uses, may *not* be the same as the one that an executable
(i.e. pg_createsubscriber). It's not correct to free memory allocated in a
shared library just with free, it has to go through the library's free.

Greetings,

Andres Freund