[Qemu-devel] [PATCH 01/18] qom: add new dynamic property infrastructure based on Visitors

[Anthony Liguori]

qdev properties are settable only during construction and static to classes.
This isn't flexible enough for QOM.

This patch introduces a property interface for qdev that provides dynamic
properties that are tied to objects, instead of classes.  These properties are
Visitor based instead of string based too.

Signed-off-by: Anthony Liguori <address@hidden>
---
 hw/qdev.c |   99 +++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/qdev.h |  118 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qerror.c  |    4 ++
 qerror.h  |    3 ++
 4 files changed, 224 insertions(+), 0 deletions(-)

diff --git a/hw/qdev.c b/hw/qdev.c
index 106407f..ad2d44f 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -390,12 +390,33 @@ void qdev_init_nofail(DeviceState *dev)
     }
 }
 
+static void qdev_property_del_all(DeviceState *dev)
+{
+    while (dev->properties) {
+        GSList *i = dev->properties;
+        DeviceProperty *prop = i->data;
+
+        dev->properties = i->next;
+
+        if (prop->release) {
+            prop->release(dev, prop->name, prop->opaque);
+        }
+
+        g_free(prop->name);
+        g_free(prop->type);
+        g_free(prop);
+        g_free(i);
+    }
+}
+
 /* Unlink device from bus and free the structure.  */
 void qdev_free(DeviceState *dev)
 {
     BusState *bus;
     Property *prop;
 
+    qdev_property_del_all(dev);
+
     if (dev->state == DEV_STATE_INITIALIZED) {
         while (dev->num_child_bus) {
             bus = QLIST_FIRST(&dev->child_bus);
@@ -962,3 +983,81 @@ char* qdev_get_fw_dev_path(DeviceState *dev)
 
     return strdup(path);
 }
+
+void qdev_property_add(DeviceState *dev, const char *name, const char *type,
+                       DevicePropertyEtter *get, DevicePropertyEtter *set,
+                       DevicePropertyRelease *release, void *opaque,
+                       Error **errp)
+{
+    DeviceProperty *prop = g_malloc0(sizeof(*prop));
+
+    prop->name = g_strdup(name);
+    prop->type = g_strdup(type);
+    prop->get = get;
+    prop->set = set;
+    prop->release = release;
+    prop->opaque = opaque;
+
+    dev->properties = g_slist_append(dev->properties, prop);
+}
+
+static DeviceProperty *qdev_property_find(DeviceState *dev, const char *name)
+{
+    GSList *i;
+
+    for (i = dev->properties; i; i = i->next) {
+        DeviceProperty *prop = i->data;
+
+        if (strcmp(prop->name, name) == 0) {
+            return prop;
+        }
+    }
+
+    return NULL;
+}
+
+void qdev_property_get(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return;
+    }
+
+    if (!prop->get) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+    } else {
+        prop->get(dev, v, prop->opaque, name, errp);
+    }
+}
+
+void qdev_property_set(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return;
+    }
+
+    if (!prop->set) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+    } else {
+        prop->set(dev, prop->opaque, v, name, errp);
+    }
+}
+
+const char *qdev_property_get_type(DeviceState *dev, const char *name, Error 
**errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return NULL;
+    }
+
+    return prop->type;
+}
diff --git a/hw/qdev.h b/hw/qdev.h
index 36a4198..0f23677 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -5,6 +5,7 @@
 #include "qemu-queue.h"
 #include "qemu-char.h"
 #include "qemu-option.h"
+#include "qapi/qapi-visit-core.h"
 
 typedef struct Property Property;
 
@@ -27,6 +28,42 @@ enum {
     DEV_NVECTORS_UNSPECIFIED = -1,
 };
 
+/**
+ * @DevicePropertyEtter - called when trying to get/set a property
+ *
+ * @dev the device that owns the property
+ * @v the visitor that contains the property data
+ * @opaque the opaque registered with the property
+ * @name the name of the property
+ * @errp a pointer to an Error that is filled if getting/setting fails.
+ */
+typedef void (DevicePropertyEtter)(DeviceState *dev,
+                                   Visitor *v,
+                                   void *opaque,
+                                   const char *name,
+                                   Error **errp);
+
+/**
+ * @DevicePropertyRelease - called when a property is removed from a device
+ *
+ * @dev the device that owns the property
+ * @name the name of the property
+ * @oapque the opaque registered with the property
+ */
+typedef void (DevicePropertyRelease)(DeviceState *dev,
+                                     const char *name,
+                                     void *opaque);
+
+typedef struct DeviceProperty
+{
+    gchar *name;
+    gchar *type;
+    DevicePropertyEtter *set;
+    DevicePropertyEtter *get;
+    DevicePropertyRelease *release;
+    void *opaque;
+} DeviceProperty;
+
 /* This structure should not be accessed directly.  We declare it here
    so that it can be embedded in individual device state structures.  */
 struct DeviceState {
@@ -45,6 +82,7 @@ struct DeviceState {
     QTAILQ_ENTRY(DeviceState) sibling;
     int instance_id_alias;
     int alias_required_for_version;
+    GSList *properties;
 };
 
 typedef void (*bus_dev_printfn)(Monitor *mon, DeviceState *dev, int indent);
@@ -329,4 +367,84 @@ char *qdev_get_fw_dev_path(DeviceState *dev);
 /* This is a nasty hack to allow passing a NULL bus to qdev_create.  */
 extern struct BusInfo system_bus_info;
 
+/**
+ * @qdev_property_add - add a new property to a device
+ *
+ * @dev - the device to add a property to
+ *
+ * @name - the name of the property.  This can contain any character except for
+ *         a forward slash.  In general, you should use hyphens '-' instead of
+ *         underscores '_' when naming properties.
+ *
+ * @type - the type name of the property.  This namespace is pretty loosely
+ *         defined.  Sub namespaces are constructed by using a prefix and then
+ *         to angle brackets.  For instance, the type 'virtio-net-pci' in the
+ *         'link' namespace would be 'link<virtio-net-pci>'.
+ *
+ * @get - the getter to be called to read a property.  If this is NULL, then
+ *        the property cannot be read.
+ *
+ * @set - the setter to be called to write a property.  If this is NULL, then
+ *        the property cannot be written.
+ *
+ * @release - called when the property is removed from the device.  This is
+ *            meant to allow a property to free its opaque upon device
+ *            destruction.  This may be NULL.
+ *
+ * @opaque - this is user data passed to @get, @set, and @release
+ *
+ * @errp - returns an error if this function fails
+ */
+void qdev_property_add(DeviceState *dev, const char *name, const char *type,
+                       DevicePropertyEtter *get, DevicePropertyEtter *set,
+                       DevicePropertyRelease *release, void *opaque,
+                       Error **errp);
+
+
+/**
+ * @qdev_property_get - reads a property from a device
+ *
+ * @dev - the device
+ *
+ * @v - the visitor that will receive the property value.  This should be an
+ *      Output visitor and the data will be written with @name as the name.
+ *
+ * @name - the name of the property
+ *
+ * @errp - returns an error if this function fails
+ */
+void qdev_property_get(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp);
+
+/**
+ * @qdev_property_set - writes a property to a device
+ *
+ * @dev - the device
+ *
+ * @v - the visitor that will used to write the property value.  This should be
+ *      an Input visitor and the data will be first read with @name as the name
+ *      and then written as the property value.
+ *
+ * @name - the name of the property
+ *
+ * @errp - returns an error if this function fails
+ */
+void qdev_property_set(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp);
+
+/**
+ * @qdev_property_get_type - returns the type of a property
+ *
+ * @dev - the device
+ *
+ * @name - the name of the property
+ *
+ * @errp - returns an error if this function fails
+ *
+ * Returns:
+ *   The type name of the property.
+ */
+const char *qdev_property_get_type(DeviceState *dev, const char *name,
+                                   Error **errp);
+
 #endif
diff --git a/qerror.c b/qerror.c
index fdf62b9..dd0ee76 100644
--- a/qerror.c
+++ b/qerror.c
@@ -178,6 +178,10 @@ static const QErrorStringTable qerror_table[] = {
         .desc      = "Could not open '%(filename)'",
     },
     {
+        .error_fmt = QERR_PERMISSION_DENIED,
+        .desc      = "Insufficient permission to perform this operation",
+    },
+    {
         .error_fmt = QERR_PROPERTY_NOT_FOUND,
         .desc      = "Property '%(device).%(property)' not found",
     },
diff --git a/qerror.h b/qerror.h
index 2d3d43b..2b1d743 100644
--- a/qerror.h
+++ b/qerror.h
@@ -150,6 +150,9 @@ QError *qobject_to_qerror(const QObject *obj);
 #define QERR_OPEN_FILE_FAILED \
     "{ 'class': 'OpenFileFailed', 'data': { 'filename': %s } }"
 
+#define QERR_PERMISSION_DENIED \
+    "{ 'class': 'PermissionDenied', 'data': {} }"
+
 #define QERR_PROPERTY_NOT_FOUND \
     "{ 'class': 'PropertyNotFound', 'data': { 'device': %s, 'property': %s } }"
 
-- 
1.7.4.1