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 2483dbbad4797e0d57cc910f2e622e2c3acf1843..aa84237e8b8f898ec7596616273141620930f186 100644 (file)
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1487,7 +1487,8 @@ 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);
@@ -1610,7 +1611,8 @@ 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);