dummy: Make --enable-dummy=override replace all dpifs, netdevs by dummies.

Plain "--enable-dummy" just creates new dummy dpif and netdev classes.
This commit makes "--enable-dummy=override" go a step farther and actually
delete and replace all the existing dpif and netdev classes by copies of
the dummy class.

This is useful for testing in an environment where changing the classes in
Bridge or Interface records is challenging.

Requested-by: Andrew Lambeth <wal@nicira.com>
Tested-by: Andrew Lambeth <wal@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

lib/dpif-netdev.c

@@ -49,6 +49,7 @@
 #include "poll-loop.h"
 #include "random.h"
 #include "shash.h"
+#include "sset.h"
 #include "timeval.h"
 #include "util.h"
 #include "vlog.h"
@@ -100,7 +101,7 @@ struct dp_netdev_port {
     int port_no;                /* Index into dp_netdev's 'ports'. */
     struct list node;           /* Element in dp_netdev's 'port_list'. */
     struct netdev *netdev;
-    bool internal;              /* Internal port? */
+    char *type;                 /* Port type as requested by user. */
 };
 
 /* A flow in dp_netdev's 'flow_table'. */
@@ -151,8 +152,6 @@ static void dp_netdev_execute_actions(struct dp_netdev *,
                                       const struct nlattr *actions,
                                       size_t actions_len);
 
-static struct dpif_class dpif_dummy_class;
-
 static struct dpif_netdev *
 dpif_netdev_cast(const struct dpif *dpif)
 {
@@ -309,28 +308,17 @@ do_add_port(struct dp_netdev *dp, const char *devname, const char *type,
 {
     struct dp_netdev_port *port;
     struct netdev *netdev;
-    bool internal;
+    const char *open_type;
     int mtu;
     int error;
 
     /* XXX reject devices already in some dp_netdev. */
-    if (type[0] == '\0' || !strcmp(type, "system") || !strcmp(type, "dummy")) {
-        internal = false;
-    } else if (!strcmp(type, "internal")) {
-        internal = true;
-    } else {
-        VLOG_WARN("%s: unsupported port type %s", devname, type);
-        return EINVAL;
-    }
 
     /* Open and validate network device. */
-    if (dp->class == &dpif_dummy_class) {
-        type = "dummy";
-    } else if (internal) {
-        type = "tap";
-    }
-
-    error = netdev_open(devname, type, &netdev);
+    open_type = (strcmp(type, "internal") ? type
+                 : dp->class != &dpif_netdev_class ? "dummy"
+                 : "tap");
+    error = netdev_open(devname, open_type, &netdev);
     if (error) {
         return error;
     }
@@ -354,7 +342,7 @@ do_add_port(struct dp_netdev *dp, const char *devname, const char *type,
     port = xmalloc(sizeof *port);
     port->port_no = port_no;
     port->netdev = netdev;
-    port->internal = internal;
+    port->type = xstrdup(type);
 
     error = netdev_get_mtu(netdev, &mtu);
     if (!error) {
@@ -374,7 +362,7 @@ choose_port(struct dpif *dpif, struct netdev *netdev)
     struct dp_netdev *dp = get_dp_netdev(dpif);
     int port_no;
 
-    if (dpif->dpif_class == &dpif_dummy_class) {
+    if (dpif->dpif_class != &dpif_netdev_class) {
         /* If the port name contains a number, try to assign that port number.
          * This can make writing unit tests easier because port numbers are
          * predictable. */
@@ -476,6 +464,7 @@ do_del_port(struct dp_netdev *dp, uint16_t port_no)
 
     name = xstrdup(netdev_get_name(port->netdev));
     netdev_close(port->netdev);
+    free(port->type);
 
     free(name);
     free(port);
@@ -488,8 +477,7 @@ answer_port_query(const struct dp_netdev_port *port,
                   struct dpif_port *dpif_port)
 {
     dpif_port->name = xstrdup(netdev_get_name(port->netdev));
-    dpif_port->type = xstrdup(port->internal ? "internal"
-                              : netdev_get_type(port->netdev));
+    dpif_port->type = xstrdup(port->type);
     dpif_port->port_no = port->port_no;
 }
 
@@ -581,8 +569,7 @@ dpif_netdev_port_dump_next(const struct dpif *dpif, void *state_,
             free(state->name);
             state->name = xstrdup(netdev_get_name(port->netdev));
             dpif_port->name = state->name;
-            dpif_port->type = (char *) (port->internal ? "internal"
-                                        : netdev_get_type(port->netdev));
+            dpif_port->type = port->type;
             dpif_port->port_no = port->port_no;
             state->port_no = port_no + 1;
             return 0;
@@ -1289,12 +1276,33 @@ const struct dpif_class dpif_netdev_class = {
     dpif_netdev_recv_purge,
 };
 
-void
-dpif_dummy_register(void)
+static void
+dpif_dummy_register__(const char *type)
 {
-    if (!dpif_dummy_class.type) {
-        dpif_dummy_class = dpif_netdev_class;
-        dpif_dummy_class.type = "dummy";
-        dp_register_provider(&dpif_dummy_class);
-    }
+    struct dpif_class *class;
+
+    class = xmalloc(sizeof *class);
+    *class = dpif_netdev_class;
+    class->type = xstrdup(type);
+    dp_register_provider(class);
+}
+
+void
+dpif_dummy_register(bool override)
+{
+    if (override) {
+        struct sset types;
+        const char *type;
+
+        sset_init(&types);
+        dp_enumerate_types(&types);
+        SSET_FOR_EACH (type, &types) {
+            if (!dp_unregister_provider(type)) {
+                dpif_dummy_register__(type);
+            }
+        }
+        sset_destroy(&types);
+    }
+
+    dpif_dummy_register__("dummy");
 }