chardev: Drop useless ChardevDummy type

Commit d0d7708b made ChardevDummy be an empty wrapper type around
ChardevCommon.  But there is no technical reason for this indirection,
so simplify the code by directly using the base type.

Also change the fallback assignment to assign u.null rather than
u.data, since a future patch will remove the data member of the C
struct generated for QAPI unions.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-Id: <1457106160-23614-1-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

backends/baum.c

@@ -567,7 +567,7 @@ static CharDriverState *chr_baum_init(const char *id,
                                       ChardevReturn *ret,
                                       Error **errp)
 {
-    ChardevCommon *common = qapi_ChardevDummy_base(backend->u.braille);
+    ChardevCommon *common = backend->u.braille;
     BaumDriverState *baum;
     CharDriverState *chr;
     brlapi_handle_t *handle;

backends/msmouse.c

@@ -68,7 +68,7 @@ static CharDriverState *qemu_chr_open_msmouse(const char *id,
                                               ChardevReturn *ret,
                                               Error **errp)
 {
-    ChardevCommon *common = qapi_ChardevDummy_base(backend->u.msmouse);
+    ChardevCommon *common = backend->u.msmouse;
     CharDriverState *chr;
 
     chr = qemu_chr_alloc(common, errp);

qapi-schema.json

@@ -3323,23 +3323,20 @@
 #
 # Since: 1.4 (testdev since 2.2)
 ##
-{ 'struct': 'ChardevDummy', 'data': { },
-  'base': 'ChardevCommon' }
-
 { 'union': 'ChardevBackend', 'data': { 'file'   : 'ChardevFile',
                                        'serial' : 'ChardevHostdev',
                                        'parallel': 'ChardevHostdev',
                                        'pipe'   : 'ChardevHostdev',
                                        'socket' : 'ChardevSocket',
                                        'udp'    : 'ChardevUdp',
-                                       'pty'    : 'ChardevDummy',
-                                       'null'   : 'ChardevDummy',
+                                       'pty'    : 'ChardevCommon',
+                                       'null'   : 'ChardevCommon',
                                        'mux'    : 'ChardevMux',
-                                       'msmouse': 'ChardevDummy',
-                                       'braille': 'ChardevDummy',
-                                       'testdev': 'ChardevDummy',
+                                       'msmouse': 'ChardevCommon',
+                                       'braille': 'ChardevCommon',
+                                       'testdev': 'ChardevCommon',
                                        'stdio'  : 'ChardevStdio',
-                                       'console': 'ChardevDummy',
+                                       'console': 'ChardevCommon',
                                        'spicevmc' : 'ChardevSpiceChannel',
                                        'spiceport' : 'ChardevSpicePort',
                                        'vc'     : 'ChardevVC',

qemu-char.c

@@ -420,7 +420,7 @@ static CharDriverState *qemu_chr_open_null(const char *id,
                                            Error **errp)
 {
     CharDriverState *chr;
-    ChardevCommon *common = qapi_ChardevDummy_base(backend->u.null);
+    ChardevCommon *common = backend->u.null;
 
     chr = qemu_chr_alloc(common, errp);
     if (!chr) {
@@ -1366,7 +1366,7 @@ static CharDriverState *qemu_chr_open_pty(const char *id,
     PtyCharDriver *s;
     int master_fd, slave_fd;
     char pty_name[PATH_MAX];
-    ChardevCommon *common = qapi_ChardevDummy_base(backend->u.pty);
+    ChardevCommon *common = backend->u.pty;
 
     master_fd = qemu_openpty_raw(&slave_fd, pty_name);
     if (master_fd < 0) {
@@ -2183,7 +2183,7 @@ static CharDriverState *qemu_chr_open_win_con(const char *id,
                                               ChardevReturn *ret,
                                               Error **errp)
 {
-    ChardevCommon *common = qapi_ChardevDummy_base(backend->u.console);
+    ChardevCommon *common = backend->u.console;
     return qemu_chr_open_win_file(GetStdHandle(STD_OUTPUT_HANDLE),
                                   common, errp);
 }
@@ -3817,7 +3817,7 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
     } else {
         ChardevCommon *cc = g_new0(ChardevCommon, 1);
         qemu_chr_parse_common(opts, cc);
-        backend->u.data = cc;
+        backend->u.null = cc; /* Any ChardevCommon member would work */
     }
 
     ret = qmp_chardev_add(bid ? bid : id, backend, errp);