qio: Provide accessor around QIONetListener->sioc

An upcoming patch needs to pass more than just sioc as the opaque
pointer to an AioContext; but since our AioContext code in general
(and its QIO Channel wrapper code) lacks a notify callback present
with GSource, we do not have the trivial option of just g_malloc'ing a
small struct to hold all that data coupled with a notify of g_free.
Instead, the data pointer must outlive the registered handler; in
fact, having the data pointer have the same lifetime as QIONetListener
is adequate.

But the cleanest way to stick such a helper struct in QIONetListener
will be to rearrange internal struct members.  And that in turn means
that all existing code that currently directly accesses
listener->nsioc and listener->sioc[] should instead go through
accessor functions, to be immune to the upcoming struct layout
changes.  So this patch adds accessor methods qio_net_listener_nsioc()
and qio_net_listener_sioc(), and puts them to use.

While at it, notice that the pattern of grabbing an sioc from the
listener only to turn around can call
qio_channel_socket_get_local_address is common enough to also warrant
the helper of qio_net_listener_get_local_address, and fix a copy-paste
error in the corresponding documentation.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20251113011625.878876-24-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

chardev/char-socket.c

@@ -1255,7 +1255,7 @@ static int qmp_chardev_open_socket_server(Chardev *chr,
     }
 
     qapi_free_SocketAddress(s->addr);
-    s->addr = qio_channel_socket_get_local_address(s->listener->sioc[0], errp);
+    s->addr = qio_net_listener_get_local_address(s->listener, 0, errp);
 
 skip_listen:
     update_disconnected_filename(s);

include/io/channel-socket.h

@@ -228,7 +228,7 @@ void qio_channel_socket_dgram_async(QIOChannelSocket *ioc,
  * release with a call qapi_free_SocketAddress() when no
  * longer required.
  *
- * Returns: 0 on success, -1 on error
+ * Returns: the socket address struct, or NULL on error
  */
 SocketAddress *
 qio_channel_socket_get_local_address(QIOChannelSocket *ioc,

include/io/net-listener.h

@@ -185,4 +185,46 @@ void qio_net_listener_disconnect(QIONetListener *listener);
  */
 bool qio_net_listener_is_connected(QIONetListener *listener);
 
+
+/**
+ * qio_net_listener_nsioc:
+ * @listener: the network listener object
+ *
+ * Determine the number of listener channels currently owned by the
+ * given listener.
+ *
+ * Returns: number of channels, or 0 if not listening
+ */
+size_t qio_net_listener_nsioc(QIONetListener *listener);
+
+
+/**
+ * qio_net_listener_sioc:
+ * @listener: the network listener object
+ * @n: index of the sioc to grab
+ *
+ * Accessor for the nth sioc owned by the listener.
+ *
+ * Returns: the requested listener, or NULL if not in bounds
+ */
+QIOChannelSocket *qio_net_listener_sioc(QIONetListener *listener, size_t n);
+
+/**
+ * qio_net_listener_get_local_address:
+ * @listener: the network listener object
+ * @n: index of the sioc to grab
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Get the string representation of the local socket
+ * address. A pointer to the allocated address information
+ * struct will be returned, which the caller is required to
+ * release with a call qapi_free_SocketAddress() when no
+ * longer required.
+ *
+ * Returns: the socket address struct, or NULL on error
+ */
+SocketAddress *
+qio_net_listener_get_local_address(QIONetListener *listener, size_t n,
+                                   Error **errp);
+
 #endif /* QIO_NET_LISTENER_H */

io/net-listener.c

@@ -316,6 +316,33 @@ bool qio_net_listener_is_connected(QIONetListener *listener)
     return listener->connected;
 }
 
+size_t qio_net_listener_nsioc(QIONetListener *listener)
+{
+    return listener->nsioc;
+}
+
+QIOChannelSocket *qio_net_listener_sioc(QIONetListener *listener, size_t n)
+{
+    if (n >= listener->nsioc) {
+        return NULL;
+    }
+    return listener->sioc[n];
+}
+
+SocketAddress *
+qio_net_listener_get_local_address(QIONetListener *listener, size_t n,
+                                   Error **errp)
+{
+    QIOChannelSocket *sioc = qio_net_listener_sioc(listener, n);
+
+    if (!sioc) {
+        error_setg(errp, "Listener index out of range");
+        return NULL;
+    }
+
+    return qio_channel_socket_get_local_address(sioc, errp);
+}
+
 static void qio_net_listener_finalize(Object *obj)
 {
     QIONetListener *listener = QIO_NET_LISTENER(obj);

migration/socket.c

@@ -170,9 +170,9 @@ void socket_start_incoming_migration(SocketAddress *saddr,
                                           NULL, NULL,
                                           g_main_context_get_thread_default());
 
-    for (i = 0; i < listener->nsioc; i++)  {
+    for (i = 0; i < qio_net_listener_nsioc(listener); i++)  {
         SocketAddress *address =
-            qio_channel_socket_get_local_address(listener->sioc[i], errp);
+            qio_net_listener_get_local_address(listener, i, errp);
         if (!address) {
             return;
         }

ui/vnc.c

@@ -235,12 +235,12 @@ static VncServerInfo *vnc_server_info_get(VncDisplay *vd)
     VncServerInfo *info;
     Error *err = NULL;
 
-    if (!vd->listener || !vd->listener->nsioc) {
+    if (!vd->listener || !qio_net_listener_nsioc(vd->listener)) {
         return NULL;
     }
 
     info = g_malloc0(sizeof(*info));
-    vnc_init_basic_info_from_server_addr(vd->listener->sioc[0],
+    vnc_init_basic_info_from_server_addr(qio_net_listener_sioc(vd->listener, 0),
                                          qapi_VncServerInfo_base(info), &err);
     info->auth = g_strdup(vnc_auth_name(vd));
     if (err) {
@@ -377,7 +377,7 @@ VncInfo *qmp_query_vnc(Error **errp)
     VncDisplay *vd = vnc_display_find(NULL);
     SocketAddress *addr = NULL;
 
-    if (vd == NULL || !vd->listener || !vd->listener->nsioc) {
+    if (vd == NULL || !vd->listener || !qio_net_listener_nsioc(vd->listener)) {
         info->enabled = false;
     } else {
         info->enabled = true;
@@ -386,8 +386,7 @@ VncInfo *qmp_query_vnc(Error **errp)
         info->has_clients = true;
         info->clients = qmp_query_client_list(vd);
 
-        addr = qio_channel_socket_get_local_address(vd->listener->sioc[0],
-                                                    errp);
+        addr = qio_net_listener_get_local_address(vd->listener, 0, errp);
         if (!addr) {
             goto out_error;
         }
@@ -549,6 +548,8 @@ VncInfo2List *qmp_query_vnc_servers(Error **errp)
     size_t i;
 
     QTAILQ_FOREACH(vd, &vnc_displays, next) {
+        size_t nsioc = 0;
+
         info = g_new0(VncInfo2, 1);
         info->id = g_strdup(vd->id);
         info->clients = qmp_query_client_list(vd);
@@ -559,14 +560,21 @@ VncInfo2List *qmp_query_vnc_servers(Error **errp)
                                                   "device", &error_abort));
             info->display = g_strdup(dev->id);
         }
-        for (i = 0; vd->listener != NULL && i < vd->listener->nsioc; i++) {
-            info->server = qmp_query_server_entry(
-                vd->listener->sioc[i], false, vd->auth, vd->subauth,
-                info->server);
+        if (vd->listener != NULL) {
+            nsioc = qio_net_listener_nsioc(vd->listener);
         }
-        for (i = 0; vd->wslistener != NULL && i < vd->wslistener->nsioc; i++) {
+        for (i = 0; i < nsioc; i++) {
             info->server = qmp_query_server_entry(
-                vd->wslistener->sioc[i], true, vd->ws_auth,
+                qio_net_listener_sioc(vd->listener, i), false, vd->auth,
+                vd->subauth, info->server);
+        }
+        nsioc = 0;
+        if (vd->wslistener) {
+            nsioc = qio_net_listener_nsioc(vd->wslistener);
+        }
+        for (i = 0; i < nsioc; i++) {
+            info->server = qmp_query_server_entry(
+                qio_net_listener_sioc(vd->wslistener, i), true, vd->ws_auth,
                 vd->ws_subauth, info->server);
         }
 
@@ -3550,11 +3558,11 @@ static void vnc_display_print_local_addr(VncDisplay *vd)
 {
     SocketAddress *addr;
 
-    if (!vd->listener || !vd->listener->nsioc) {
+    if (!vd->listener || !qio_net_listener_nsioc(vd->listener)) {
         return;
     }
 
-    addr = qio_channel_socket_get_local_address(vd->listener->sioc[0], NULL);
+    addr = qio_net_listener_get_local_address(vd->listener, 0, NULL);
     if (!addr) {
         return;
     }