Fix null pointer dereference in "\c" psql command.

The psql crash happened when no current connection existed.  (The second
new check is optional given today's undocumented NULL argument handling
in PQhost() etc.)  Back-patch to 9.0 (all supported versions).

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 89bda00d1ae09aa772659dae6f94cd2983215660..b65584312256653922a0e521ee9de70ca5c5b300 100644 (file)
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1591,7 +1591,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
     * syntax.
     */
    keep_password =
-       ((strcmp(user, PQuser(o_conn)) == 0) &&
+       (o_conn &&
+        (strcmp(user, PQuser(o_conn)) == 0) &&
         (!host || strcmp(host, PQhost(o_conn)) == 0) &&
         (strcmp(port, PQport(o_conn)) == 0) &&
         !has_connection_string);
@@ -1718,7 +1719,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
    /* Tell the user about the new connection */
    if (!pset.quiet)
    {
-       if (param_is_newly_set(PQhost(o_conn), PQhost(pset.db)) ||
+       if (!o_conn ||
+           param_is_newly_set(PQhost(o_conn), PQhost(pset.db)) ||
            param_is_newly_set(PQport(o_conn), PQport(pset.db)))
        {
            char       *host = PQhost(pset.db);