qemu-char: add create to register_char_driver

Having creation as a member of the CharDriver struct removes the need
to export functions for qemu-char.c's usage.  After the conversion,
chardev backends implemented outside qemu-char.c will not need a stub
creation function anymore.

Ultimately all drivers will be converted.  For now, support the case
where cd->create == NULL.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

backends/baum.c

@@ -629,7 +629,8 @@ fail_handle:
 
 static void register_types(void)
 {
-    register_char_driver("braille", CHARDEV_BACKEND_KIND_BRAILLE, NULL);
+    register_char_driver("braille", CHARDEV_BACKEND_KIND_BRAILLE, NULL,
+                         NULL);
 }
 
 type_init(register_types);

backends/msmouse.c

@@ -79,7 +79,8 @@ CharDriverState *qemu_chr_open_msmouse(void)
 
 static void register_types(void)
 {
-    register_char_driver("msmouse", CHARDEV_BACKEND_KIND_MSMOUSE, NULL);
+    register_char_driver("msmouse", CHARDEV_BACKEND_KIND_MSMOUSE, NULL,
+                         NULL);
 }
 
 type_init(register_types);

backends/testdev.c

@@ -125,7 +125,8 @@ CharDriverState *chr_testdev_init(void)
 
 static void register_types(void)
 {
-    register_char_driver("testdev", CHARDEV_BACKEND_KIND_TESTDEV, NULL);
+    register_char_driver("testdev", CHARDEV_BACKEND_KIND_TESTDEV, NULL,
+                         NULL);
 }
 
 type_init(register_types);

include/sysemu/char.h

@@ -345,7 +345,9 @@ bool chr_is_ringbuf(const CharDriverState *chr);
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
 
 void register_char_driver(const char *name, ChardevBackendKind kind,
-        void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp));
+        void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp),
+        CharDriverState *(*create)(const char *id, ChardevBackend *backend,
+                                   ChardevReturn *ret, Error **errp));
 
 /* add an eventfd to the qemu devices that are polled */
 CharDriverState *qemu_chr_open_eventfd(int eventfd);

qemu-char.c

@@ -3644,12 +3644,16 @@ typedef struct CharDriver {
     const char *name;
     ChardevBackendKind kind;
     void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
+    CharDriverState *(*create)(const char *id, ChardevBackend *backend,
+                               ChardevReturn *ret, Error **errp);
 } CharDriver;
 
 static GSList *backends;
 
 void register_char_driver(const char *name, ChardevBackendKind kind,
-        void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp))
+        void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp),
+        CharDriverState *(*create)(const char *id, ChardevBackend *backend,
+                                   ChardevReturn *ret, Error **errp))
 {
     CharDriver *s;
 
@@ -3657,6 +3661,7 @@ void register_char_driver(const char *name, ChardevBackendKind kind,
     s->name = g_strdup(name);
     s->kind = kind;
     s->parse = parse;
+    s->create = create;
 
     backends = g_slist_append(backends, s);
 }
@@ -4211,6 +4216,8 @@ ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
     ChardevReturn *ret = g_new0(ChardevReturn, 1);
     CharDriverState *base, *chr = NULL;
     Error *local_err = NULL;
+    GSList *i;
+    CharDriver *cd;
 
     chr = qemu_chr_find(id);
     if (chr) {
@@ -4219,6 +4226,20 @@ ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
         return NULL;
     }
 
+    for (i = backends; i; i = i->next) {
+        cd = i->data;
+
+        if (cd->kind == backend->kind && cd->create) {
+            chr = cd->create(id, backend, ret, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                goto out_error;
+            }
+            break;
+        }
+    }
+
+    if (chr == NULL) {
         switch (backend->kind) {
         case CHARDEV_BACKEND_KIND_FILE:
             chr = qmp_chardev_open_file(backend->file, &local_err);
@@ -4312,6 +4333,7 @@ ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
             }
             goto out_error;
         }
+    }
 
     chr->label = g_strdup(id);
     chr->avail_connections =
@@ -4349,32 +4371,37 @@ void qmp_chardev_remove(const char *id, Error **errp)
 
 static void register_types(void)
 {
-    register_char_driver("null", CHARDEV_BACKEND_KIND_NULL, NULL);
+    register_char_driver("null", CHARDEV_BACKEND_KIND_NULL, NULL,
+                         NULL);
     register_char_driver("socket", CHARDEV_BACKEND_KIND_SOCKET,
-                         qemu_chr_parse_socket);
+                         qemu_chr_parse_socket, NULL);
-    register_char_driver("udp", CHARDEV_BACKEND_KIND_UDP, qemu_chr_parse_udp);
+    register_char_driver("udp", CHARDEV_BACKEND_KIND_UDP, qemu_chr_parse_udp,
+                         NULL);
     register_char_driver("ringbuf", CHARDEV_BACKEND_KIND_RINGBUF,
-                         qemu_chr_parse_ringbuf);
+                         qemu_chr_parse_ringbuf, NULL);
     register_char_driver("file", CHARDEV_BACKEND_KIND_FILE,
-                         qemu_chr_parse_file_out);
+                         qemu_chr_parse_file_out, NULL);
     register_char_driver("stdio", CHARDEV_BACKEND_KIND_STDIO,
-                         qemu_chr_parse_stdio);
+                         qemu_chr_parse_stdio, NULL);
     register_char_driver("serial", CHARDEV_BACKEND_KIND_SERIAL,
-                         qemu_chr_parse_serial);
+                         qemu_chr_parse_serial, NULL);
     register_char_driver("tty", CHARDEV_BACKEND_KIND_SERIAL,
-                         qemu_chr_parse_serial);
+                         qemu_chr_parse_serial, NULL);
     register_char_driver("parallel", CHARDEV_BACKEND_KIND_PARALLEL,
-                         qemu_chr_parse_parallel);
+                         qemu_chr_parse_parallel, NULL);
     register_char_driver("parport", CHARDEV_BACKEND_KIND_PARALLEL,
-                         qemu_chr_parse_parallel);
+                         qemu_chr_parse_parallel, NULL);
-    register_char_driver("pty", CHARDEV_BACKEND_KIND_PTY, NULL);
+    register_char_driver("pty", CHARDEV_BACKEND_KIND_PTY, NULL,
-    register_char_driver("console", CHARDEV_BACKEND_KIND_CONSOLE, NULL);
+                         NULL);
+    register_char_driver("console", CHARDEV_BACKEND_KIND_CONSOLE, NULL,
+                         NULL);
     register_char_driver("pipe", CHARDEV_BACKEND_KIND_PIPE,
-                         qemu_chr_parse_pipe);
+                         qemu_chr_parse_pipe, NULL);
-    register_char_driver("mux", CHARDEV_BACKEND_KIND_MUX, qemu_chr_parse_mux);
+    register_char_driver("mux", CHARDEV_BACKEND_KIND_MUX, qemu_chr_parse_mux,
+                         NULL);
     /* Bug-compatibility: */
     register_char_driver("memory", CHARDEV_BACKEND_KIND_MEMORY,
-                         qemu_chr_parse_ringbuf);
+                         qemu_chr_parse_ringbuf, NULL);
     /* this must be done after machine init, since we register FEs with muxes
      * as part of realize functions like serial_isa_realizefn when -nographic
      * is specified

spice-qemu-char.c

@@ -379,9 +379,9 @@ static void qemu_chr_parse_spice_port(QemuOpts *opts, ChardevBackend *backend,
 static void register_types(void)
 {
     register_char_driver("spicevmc", CHARDEV_BACKEND_KIND_SPICEVMC,
-                         qemu_chr_parse_spice_vmc);
+                         qemu_chr_parse_spice_vmc, NULL);
     register_char_driver("spiceport", CHARDEV_BACKEND_KIND_SPICEPORT,
-                         qemu_chr_parse_spice_port);
+                         qemu_chr_parse_spice_port, NULL);
 }
 
 type_init(register_types);

ui/console.c

@@ -2093,7 +2093,8 @@ static const TypeInfo qemu_console_info = {
 static void register_types(void)
 {
     type_register_static(&qemu_console_info);
-    register_char_driver("vc", CHARDEV_BACKEND_KIND_VC, qemu_chr_parse_vc);
+    register_char_driver("vc", CHARDEV_BACKEND_KIND_VC, qemu_chr_parse_vc,
+                         NULL);
 }
 
 type_init(register_types);