Fix ancient connection leak in dblink

When using unnamed connections with dblink, every time a new
connection is made, the old one is leaked. Fix that.

This has been an issue probably since dblink was first committed.
Someone complained almost ten years ago, but apparently I decided
not to pursue it at the time, and neither did anyone else, so it
slipped between the cracks. Now that someone else has complained,
fix in all supported branches.

Discussion: (orig) https://postgr.es/m/flat/F680AB59-6D6F-4026-9599-1BE28880273D%40decibel.org#F680AB59-6D6F-4026-9599-1BE28880273D@decibel.org
Discussion: (new) https://postgr.es/m/flat/0A3221C70F24FB45833433255569204D1F6ADF8C@G01JPEXMBYT05
Reported by: Jim Nasby and Takayuki Tsunakawa

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index c0cdd8f1182271e06c3469758d430ffd15ec14f7..eba6f274dc68e0277f60bb7d1cae5233c36c82c9 100644 (file)
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -304,7 +304,11 @@ dblink_connect(PG_FUNCTION_ARGS)
                createNewConnection(connname, rconn);
        }
        else
+       {
+               if (pconn->conn)
+                       PQfinish(pconn->conn);
                pconn->conn = conn;
+       }
 
        PG_RETURN_TEXT_P(cstring_to_text("OK"));
 }