monitor: Add set_link arguments completion.

Make it possible to query all net clients without specifying an ID when calling
qemu_find_net_clients_except().

This also adds the add_completion_option() function which is to be used for
other commands completions as well.
Signed-off-by: NHani Benhabiles <hani@linux.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

hmp-commands.hx

@@ -1340,6 +1340,7 @@ ETEXI
         .params     = "name on|off",
         .help       = "change the link status of a network adapter",
         .mhandler.cmd = hmp_set_link,
+        .command_completion = set_link_completion,
     },
 
 STEXI

hmp.h

@@ -100,5 +100,6 @@ void device_del_completion(ReadLineState *rs, int nb_args, const char *str);
 void sendkey_completion(ReadLineState *rs, int nb_args, const char *str);
 void chardev_remove_completion(ReadLineState *rs, int nb_args, const char *str);
 void chardev_add_completion(ReadLineState *rs, int nb_args, const char *str);
+void set_link_completion(ReadLineState *rs, int nb_args, const char *str);
 
 #endif

monitor.c

@@ -4269,6 +4269,17 @@ static const char *next_arg_type(const char *typestr)
     return (p != NULL ? ++p : typestr);
 }
 
+static void add_completion_option(ReadLineState *rs, const char *str,
+                                  const char *option)
+{
+    if (!str || !option) {
+        return;
+    }
+    if (!strncmp(option, str, strlen(str))) {
+        readline_add_completion(rs, option);
+    }
+}
+
 void chardev_add_completion(ReadLineState *rs, int nb_args, const char *str)
 {
     size_t len;
@@ -4444,6 +4455,29 @@ void sendkey_completion(ReadLineState *rs, int nb_args, const char *str)
     }
 }
 
+void set_link_completion(ReadLineState *rs, int nb_args, const char *str)
+{
+    size_t len;
+
+    len = strlen(str);
+    readline_set_completion_index(rs, len);
+    if (nb_args == 2) {
+        NetClientState *ncs[255];
+        int count, i;
+        count = qemu_find_net_clients_except(NULL, ncs,
+                                             NET_CLIENT_OPTIONS_KIND_NONE, 255);
+        for (i = 0; i < count; i++) {
+            const char *name = ncs[i]->name;
+            if (!strncmp(str, name, len)) {
+                readline_add_completion(rs, name);
+            }
+        }
+    } else if (nb_args == 3) {
+        add_completion_option(rs, str, "on");
+        add_completion_option(rs, str, "off");
+    }
+}
+
 static void monitor_find_completion_by_table(Monitor *mon,
                                              const mon_cmd_t *cmd_table,
                                              char **args,

net/net.c

@@ -633,7 +633,7 @@ int qemu_find_net_clients_except(const char *id, NetClientState **ncs,
         if (nc->info->type == type) {
             continue;
         }
-        if (!strcmp(nc->name, id)) {
+        if (!id || !strcmp(nc->name, id)) {
             if (ret < max) {
                 ncs[ret] = nc;
             }