net: Move NetClientState.info_str to dynamic allocations

The info_str field of the NetClientState structure is static and has a size
of 256 bytes. This amount is often unclaimed, and the field itself is used
exclusively for HMP "info network".

The patch translates info_str to dynamic memory allocation.

This action is also allows us to painlessly discard usage of this field
for backend devices.

Signed-off-by: Alexey Kirillov <lekiravi@yandex-team.ru>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/net.c b/net/net.c
index 9a2a6ab155..277da712eb 100644
--- a/net/net.c
+++ b/net/net.c
@@ -129,11 +129,12 @@ char *qemu_mac_strdup_printf(const uint8_t *macaddr)
 
 void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6])
 {
-    snprintf(nc->info_str, sizeof(nc->info_str),
-             "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-             nc->model,
-             macaddr[0], macaddr[1], macaddr[2],
-             macaddr[3], macaddr[4], macaddr[5]);
+    g_free(nc->info_str);
+    nc->info_str = g_strdup_printf(
+        "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
+        nc->model,
+        macaddr[0], macaddr[1], macaddr[2],
+        macaddr[3], macaddr[4], macaddr[5]);
 }
 
 static int mac_table[256] = {0};
@@ -352,6 +353,7 @@ static void qemu_free_net_client(NetClientState *nc)
     }
     g_free(nc->name);
     g_free(nc->model);
+    g_free(nc->info_str);
     qapi_free_NetdevInfo(nc->stored_config);
     if (nc->destructor) {
         nc->destructor(nc);
@@ -1226,7 +1228,7 @@ void print_net_client(Monitor *mon, NetClientState *nc)
     monitor_printf(mon, "%s: index=%d,type=%s,%s\n", nc->name,
                    nc->queue_index,
                    NetClientDriver_str(nc->info->type),
-                   nc->info_str);
+                   nc->info_str ? nc->info_str : "");
     if (!QTAILQ_EMPTY(&nc->filters)) {
         monitor_printf(mon, "filters:\n");
     }