qapi: convert netdev_add

This is not a full QAPI conversion, but an intermediate step.

In essence, do_netdev_add() is split into three functions:

 1. netdev_add(): performs the actual work. This function is fully
    converted to Error (thus, it's "qapi-friendly")

 2. qmp_netdev_add(): the QMP front-end for netdev_add(). This is
    coded by hand and not auto-generated (gen=no in the schema). The
    reason for this it's a lot easier and simpler to with QemuOpts
    this way

 3. hmp_netdev_add(): HMP front-end.

This design was suggested by Paolo Bonzini.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-By: Laszlo Ersek <lersek@redhat.com>

hmp-commands.hx

@@ -1037,8 +1037,7 @@ ETEXI
         .args_type  = "netdev:O",
         .params     = "[user|tap|socket],id=str[,prop=value][,...]",
         .help       = "add host network device",
-        .user_print = monitor_user_noop,
-        .mhandler.cmd_new = do_netdev_add,
+        .mhandler.cmd = hmp_netdev_add,
     },
 
 STEXI

hmp.c

@@ -14,6 +14,8 @@
  */
 
 #include "hmp.h"
+#include "net.h"
+#include "qemu-option.h"
 #include "qemu-timer.h"
 #include "qmp-commands.h"
 
@@ -969,3 +971,22 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
                           &errp);
     hmp_handle_error(mon, &errp);
 }
+
+void hmp_netdev_add(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+    QemuOpts *opts;
+
+    opts = qemu_opts_from_qdict(qemu_find_opts("netdev"), qdict, &err);
+    if (error_is_set(&err)) {
+        goto out;
+    }
+
+    netdev_add(opts, &err);
+    if (error_is_set(&err)) {
+        qemu_opts_del(opts);
+    }
+
+out:
+    hmp_handle_error(mon, &err);
+}

hmp.h

@@ -62,5 +62,6 @@ void hmp_block_job_cancel(Monitor *mon, const QDict *qdict);
 void hmp_migrate(Monitor *mon, const QDict *qdict);
 void hmp_device_del(Monitor *mon, const QDict *qdict);
 void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict);
+void hmp_netdev_add(Monitor *mon, const QDict *qdict);
 
 #endif

net.c

@@ -1234,27 +1234,39 @@ void net_host_device_remove(Monitor *mon, const QDict *qdict)
     qemu_del_vlan_client(vc);
 }
 
-int do_netdev_add(Monitor *mon, const QDict *qdict, QObject **ret_data)
+void netdev_add(QemuOpts *opts, Error **errp)
+{
+    net_client_init(opts, 1, errp);
+}
+
+int qmp_netdev_add(Monitor *mon, const QDict *qdict, QObject **ret)
 {
     Error *local_err = NULL;
+    QemuOptsList *opts_list;
     QemuOpts *opts;
-    int res;
 
-    opts = qemu_opts_from_qdict(qemu_find_opts("netdev"), qdict, &local_err);
-    if (!opts) {
-        qerror_report_err(local_err);
-        error_free(local_err);
-        return -1;
+    opts_list = qemu_find_opts_err("netdev", &local_err);
+    if (error_is_set(&local_err)) {
+        goto exit_err;
     }
 
-    res = net_client_init(opts, 1, &local_err);
-    if (res < 0) {
-        qerror_report_err(local_err);
-        error_free(local_err);
+    opts = qemu_opts_from_qdict(opts_list, qdict, &local_err);
+    if (error_is_set(&local_err)) {
+        goto exit_err;
+    }
+
+    netdev_add(opts, &local_err);
+    if (error_is_set(&local_err)) {
         qemu_opts_del(opts);
+        goto exit_err;
     }
 
-    return res;
+    return 0;
+
+exit_err:
+    qerror_report_err(local_err);
+    error_free(local_err);
+    return -1;
 }
 
 int do_netdev_del(Monitor *mon, const QDict *qdict, QObject **ret_data)

net.h

@@ -170,7 +170,8 @@ void net_check_clients(void);
 void net_cleanup(void);
 void net_host_device_add(Monitor *mon, const QDict *qdict);
 void net_host_device_remove(Monitor *mon, const QDict *qdict);
-int do_netdev_add(Monitor *mon, const QDict *qdict, QObject **ret_data);
+void netdev_add(QemuOpts *opts, Error **errp);
+int qmp_netdev_add(Monitor *mon, const QDict *qdict, QObject **ret);
 int do_netdev_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
 
 #define DEFAULT_NETWORK_SCRIPT "/etc/qemu-ifup"

qapi-schema.json

@@ -1798,3 +1798,31 @@
 { 'command': 'dump-guest-memory',
   'data': { 'paging': 'bool', 'protocol': 'str', '*begin': 'int',
             '*length': 'int' } }
+##
+# @netdev_add:
+#
+# Add a network backend.
+#
+# @type: the type of network backend.  Current valid values are 'user', 'tap',
+#        'vde', 'socket', 'dump' and 'bridge'
+#
+# @id: the name of the new network backend
+#
+# @props: #optional a list of properties to be passed to the backend in
+#         the format 'name=value', like 'ifname=tap0,script=no'
+#
+# Notes: The semantics of @props is not well defined.  Future commands will be
+#        introduced that provide stronger typing for backend creation.
+#
+# Since: 0.14.0
+#
+# Returns: Nothing on success
+#          If @type is not a valid network backend, DeviceNotFound
+#          If @id is not a valid identifier, InvalidParameterValue
+#          if @id already exists, DuplicateId
+#          If @props contains an invalid parameter for this backend,
+#            InvalidParameter
+##
+{ 'command': 'netdev_add',
+  'data': {'type': 'str', 'id': 'str', '*props': '**'},
+  'gen': 'no' }

qmp-commands.hx

@@ -642,10 +642,7 @@ EQMP
     {
         .name       = "netdev_add",
         .args_type  = "netdev:O",
-        .params     = "[user|tap|socket],id=str[,prop=value][,...]",
-        .help       = "add host network device",
-        .user_print = monitor_user_noop,
-        .mhandler.cmd_new = do_netdev_add,
+        .mhandler.cmd_new = qmp_netdev_add,
     },
 
 SQMP