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 2728216022efaa5de0d6151552622262b99f40cb..6181a6167857b55e99ca4779768a86654d4984a8 100644 (file)
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1753,7 +1753,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
     * positional 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);
@@ -1880,7 +1881,8 @@ 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);