Re: BUG #19547: libpqrcv_create_slot dereferences NULL on a malformed CREATE_REPLICATION_SLOT reply

On Wed, Jul 15, 2026 at 8:51 PM Kenny Chen  wrote:
> Agreed.  IDENTIFY_SYSTEM tolerates 3 columns only because older servers (9.3
> and earlier) actually returned 3, whereas CREATE_REPLICATION_SLOT has always
> returned 4, so there is no reason to be lenient here.  v2 attached requires 4
> fields, and updates the comment and errdetail accordingly.

Agreed. So,

+       if (PQnfields(res) < 4 || PQntuples(res) != 1)
+               ereport(ERROR,
+                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                                errmsg("invalid response from primary server"),
+                                errdetail("Could not create
replication slot \"%s\": got %d rows and %d fields, expected %d rows
and %d or more fields.",
+                                                  slotname,
PQntuples(res), PQnfields(res), 1, 4)));

"PQnfields(res) < 4" should be "PQnfields(res) != 4"?
If so, "or more" in the detail message should be removed as well.

Regards,

-- 
Fujii Masao