net: report list of available models according to platform

By noting the models for which a configuration was requested, we can give
the user an accurate list of which NIC models were actually available on
the platform/configuration that was otherwise chosen.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

net/net.c

@@ -75,6 +75,8 @@ typedef QSIMPLEQ_HEAD(, NetdevQueueEntry) NetdevQueue;
 
 static NetdevQueue nd_queue = QSIMPLEQ_HEAD_INITIALIZER(nd_queue);
 
+static GHashTable *nic_model_help;
+
 /***********************************************************/
 /* network device redirectors */
 
@@ -1087,12 +1089,94 @@ static int net_init_nic(const Netdev *netdev, const char *name,
     return idx;
 }
 
+static gboolean add_nic_result(gpointer key, gpointer value, gpointer user_data)
+{
+    GPtrArray *results = user_data;
+    GPtrArray *alias_list = value;
+    const char *model = key;
+    char *result;
+
+    if (!alias_list) {
+        result = g_strdup(model);
+    } else {
+        GString *result_str = g_string_new(model);
+        int i;
+
+        g_string_append(result_str, " (aka ");
+        for (i = 0; i < alias_list->len; i++) {
+            if (i) {
+                g_string_append(result_str, ", ");
+            }
+            g_string_append(result_str, alias_list->pdata[i]);
+        }
+        g_string_append(result_str, ")");
+        result = result_str->str;
+        g_string_free(result_str, false);
+        g_ptr_array_unref(alias_list);
+    }
+    g_ptr_array_add(results, result);
+    return true;
+}
+
+static int model_cmp(char **a, char **b)
+{
+    return strcmp(*a, *b);
+}
+
+static void show_nic_models(void)
+{
+    GPtrArray *results = g_ptr_array_new();
+    int i;
+
+    g_hash_table_foreach_remove(nic_model_help, add_nic_result, results);
+    g_ptr_array_sort(results, (GCompareFunc)model_cmp);
+
+    printf("Available NIC models for this configuration:\n");
+    for (i = 0 ; i < results->len; i++) {
+        printf("%s\n", (char *)results->pdata[i]);
+    }
+    g_hash_table_unref(nic_model_help);
+    nic_model_help = NULL;
+}
+
+static void add_nic_model_help(const char *model, const char *alias)
+{
+    GPtrArray *alias_list = NULL;
+
+    if (g_hash_table_lookup_extended(nic_model_help, model, NULL,
+                                     (gpointer *)&alias_list)) {
+        /* Already exists, no alias to add: return */
+        if (!alias) {
+            return;
+        }
+        if (alias_list) {
+            /* Check if this alias is already in the list. Add if not. */
+            if (!g_ptr_array_find_with_equal_func(alias_list, alias,
+                                                  g_str_equal, NULL)) {
+                g_ptr_array_add(alias_list, g_strdup(alias));
+            }
+            return;
+        }
+    }
+    /* Either this model wasn't in the list already, or a first alias added */
+    if (alias) {
+        alias_list = g_ptr_array_new();
+        g_ptr_array_set_free_func(alias_list, g_free);
+        g_ptr_array_add(alias_list, g_strdup(alias));
+    }
+    g_hash_table_replace(nic_model_help, g_strdup(model), alias_list);
+}
+
 NICInfo *qemu_find_nic_info(const char *typename, bool match_default,
                             const char *alias)
 {
     NICInfo *nd;
     int i;
 
+    if (nic_model_help) {
+        add_nic_model_help(typename, alias);
+    }
+
     for (i = 0; i < nb_nics; i++) {
         nd = &nd_table[i];
 
@@ -1606,6 +1690,10 @@ void net_check_clients(void)
     NetClientState *nc;
     int i;
 
+    if (nic_model_help) {
+        show_nic_models();
+        exit(0);
+    }
     net_hub_check_clients();
 
     QTAILQ_FOREACH(nc, &net_clients, next) {
@@ -1685,6 +1773,12 @@ static int net_param_nic(void *dummy, QemuOpts *opts, Error **errp)
     memset(ni, 0, sizeof(*ni));
     ni->model = qemu_opt_get_del(opts, "model");
 
+    if (!nic_model_help && !g_strcmp0(ni->model, "help")) {
+        nic_model_help = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                               g_free, NULL);
+        return 0;
+    }
+
     /* Create an ID if the user did not specify one */
     nd_id = g_strdup(qemu_opts_id(opts));
     if (!nd_id) {