ctdb-daemon: Avoid referencing NULL pointer due to unknown old interface

This doesn't currently happen but it will in a subsequent commit.
That commit and this one could be squashed but then the functional
change gets lost in amongst this one.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

diff --git a/ctdb/server/ctdb_takeover.c b/ctdb/server/ctdb_takeover.c
index 879b2171840a58b5e76d32e2208c0befcdec0b5b..fe4a234c55ff102a85af11251ab4e2bf387e70f2 100644 (file)
--- a/ctdb/server/ctdb_takeover.c
+++ b/ctdb/server/ctdb_takeover.c
@@ -88,13 +88,14 @@ struct ctdb_vnn {
        bool delete_pending;
 };
 
-static const char *ctdb_vnn_iface_string(const struct ctdb_vnn *vnn)
+static const char *iface_string(const struct ctdb_interface *iface)
 {
-       if (vnn->iface) {
-               return vnn->iface->name;
-       }
+       return (iface != NULL ? iface->name : "__none__");
+}
 
-       return "__none__";
+static const char *ctdb_vnn_iface_string(const struct ctdb_vnn *vnn)
+{
+       return iface_string(vnn->iface);
 }
 
 static int ctdb_add_local_iface(struct ctdb_context *ctdb, const char *iface)
@@ -580,10 +581,11 @@ static void ctdb_do_updateip_callback(struct ctdb_context *ctdb, int status,
                if (status == -ETIME) {
                        ctdb_ban_self(ctdb);
                }
-               DEBUG(DEBUG_ERR,(__location__ " Failed to move IP %s from interface %s to %s\n",
-                       ctdb_addr_to_str(&state->vnn->public_address),
-                       state->old->name,
-                       ctdb_vnn_iface_string(state->vnn)));
+               DEBUG(DEBUG_ERR,
+                     ("Failed update of IP %s from interface %s to %s\n",
+                      ctdb_addr_to_str(&state->vnn->public_address),
+                      iface_string(state->old),
+                      ctdb_vnn_iface_string(state->vnn)));
 
                /*
                 * All we can do is reset the old interface
@@ -631,6 +633,7 @@ static int32_t ctdb_do_updateip(struct ctdb_context *ctdb,
        int ret;
        struct ctdb_do_updateip_state *state;
        struct ctdb_interface *old = vnn->iface;
+       const char *old_name = iface_string(old);
        const char *new_name;
 
        if (vnn->update_in_flight) {
@@ -644,16 +647,17 @@ static int32_t ctdb_do_updateip(struct ctdb_context *ctdb,
        ctdb_vnn_unassign_iface(ctdb, vnn);
        ret = ctdb_vnn_assign_iface(ctdb, vnn);
        if (ret != 0) {
-               DEBUG(DEBUG_ERR,("update of IP %s/%u failed to "
-                                "assin a usable interface (old iface '%s')\n",
+               DEBUG(DEBUG_ERR,("Update of IP %s/%u failed to "
+                                "assign a usable interface (old iface '%s')\n",
                                 ctdb_addr_to_str(&vnn->public_address),
                                 vnn->public_netmask_bits,
-                                old->name));
+                                old_name));
                return -1;
        }
 
        new_name = ctdb_vnn_iface_string(vnn);
-       if (old->name != NULL && new_name != NULL && !strcmp(old->name, new_name)) {
+       if (old_name != NULL && new_name != NULL &&
+           strcmp(old_name, new_name) == 0) {
                /* A benign update from one interface onto itself.
                 * no need to run the eventscripts in this case, just return
                 * success.
@@ -676,7 +680,7 @@ static int32_t ctdb_do_updateip(struct ctdb_context *ctdb,
                            "interface %s to %s\n",
                            ctdb_addr_to_str(&vnn->public_address),
                            vnn->public_netmask_bits,
-                           old->name,
+                           old_name,
                            new_name));
 
        ret = ctdb_event_script_callback(ctdb,
@@ -685,14 +689,15 @@ static int32_t ctdb_do_updateip(struct ctdb_context *ctdb,
                                         state,
                                         CTDB_EVENT_UPDATE_IP,
                                         "%s %s %s %u",
-                                        state->old->name,
+                                        old_name,
                                         new_name,
                                         ctdb_addr_to_str(&vnn->public_address),
                                         vnn->public_netmask_bits);
        if (ret != 0) {
-               DEBUG(DEBUG_ERR,(__location__ " Failed update IP %s from interface %s to %s\n",
-                                ctdb_addr_to_str(&vnn->public_address),
-                                old->name, new_name));
+               DEBUG(DEBUG_ERR,
+                     ("Failed update IP %s from interface %s to %s\n",
+                      ctdb_addr_to_str(&vnn->public_address),
+                      old_name, new_name));
                talloc_free(state);
                return -1;
        }