Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 280 insertions, 0 deletions

diff --git a/qapi/qobject-output-visitor.c b/qapi/qobject-output-visitor.c
new file mode 100644
index 000000000..74770edd7
--- /dev/null
+++ b/qapi/qobject-output-visitor.c
@@ -0,0 +1,280 @@
+/*
+ * Core Definitions for QAPI/QMP Command Registry
+ *
+ * Copyright (C) 2012-2016 Red Hat, Inc.
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/compat-policy.h"
+#include "qapi/qobject-output-visitor.h"
+#include "qapi/visitor-impl.h"
+#include "qemu/queue.h"
+#include "qapi/qmp/qbool.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qlist.h"
+#include "qapi/qmp/qnull.h"
+#include "qapi/qmp/qnum.h"
+#include "qapi/qmp/qstring.h"
+
+typedef struct QStackEntry {
+    QObject *value;
+    void *qapi; /* sanity check that caller uses same pointer */
+    QSLIST_ENTRY(QStackEntry) node;
+} QStackEntry;
+
+struct QObjectOutputVisitor {
+    Visitor visitor;
+
+    QSLIST_HEAD(, QStackEntry) stack; /* Stack of unfinished containers */
+    QObject *root; /* Root of the output visit */
+    QObject **result; /* User's storage location for result */
+};
+
+#define qobject_output_add(qov, name, value) \
+    qobject_output_add_obj(qov, name, QOBJECT(value))
+#define qobject_output_push(qov, value, qapi) \
+    qobject_output_push_obj(qov, QOBJECT(value), qapi)
+
+static QObjectOutputVisitor *to_qov(Visitor *v)
+{
+    return container_of(v, QObjectOutputVisitor, visitor);
+}
+
+/* Push @value onto the stack of current QObjects being built */
+static void qobject_output_push_obj(QObjectOutputVisitor *qov, QObject *value,
+                                    void *qapi)
+{
+    QStackEntry *e = g_malloc0(sizeof(*e));
+
+    assert(qov->root);
+    assert(value);
+    e->value = value;
+    e->qapi = qapi;
+    QSLIST_INSERT_HEAD(&qov->stack, e, node);
+}
+
+/* Pop a value off the stack of QObjects being built, and return it. */
+static QObject *qobject_output_pop(QObjectOutputVisitor *qov, void *qapi)
+{
+    QStackEntry *e = QSLIST_FIRST(&qov->stack);
+    QObject *value;
+
+    assert(e);
+    assert(e->qapi == qapi);
+    QSLIST_REMOVE_HEAD(&qov->stack, node);
+    value = e->value;
+    assert(value);
+    g_free(e);
+    return value;
+}
+
+/* Add @value to the current QObject being built.
+ * If the stack is visiting a dictionary or list, @value is now owned
+ * by that container. Otherwise, @value is now the root.  */
+static void qobject_output_add_obj(QObjectOutputVisitor *qov, const char *name,
+                                   QObject *value)
+{
+    QStackEntry *e = QSLIST_FIRST(&qov->stack);
+    QObject *cur = e ? e->value : NULL;
+
+    if (!cur) {
+        /* Don't allow reuse of visitor on more than one root */
+        assert(!qov->root);
+        qov->root = value;
+    } else {
+        switch (qobject_type(cur)) {
+        case QTYPE_QDICT:
+            assert(name);
+            qdict_put_obj(qobject_to(QDict, cur), name, value);
+            break;
+        case QTYPE_QLIST:
+            assert(!name);
+            qlist_append_obj(qobject_to(QList, cur), value);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
+}
+
+static bool qobject_output_start_struct(Visitor *v, const char *name,
+                                        void **obj, size_t unused, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    QDict *dict = qdict_new();
+
+    qobject_output_add(qov, name, dict);
+    qobject_output_push(qov, dict, obj);
+    return true;
+}
+
+static void qobject_output_end_struct(Visitor *v, void **obj)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    QObject *value = qobject_output_pop(qov, obj);
+    assert(qobject_type(value) == QTYPE_QDICT);
+}
+
+static bool qobject_output_start_list(Visitor *v, const char *name,
+                                      GenericList **listp, size_t size,
+                                      Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    QList *list = qlist_new();
+
+    qobject_output_add(qov, name, list);
+    qobject_output_push(qov, list, listp);
+    return true;
+}
+
+static GenericList *qobject_output_next_list(Visitor *v, GenericList *tail,
+                                             size_t size)
+{
+    return tail->next;
+}
+
+static void qobject_output_end_list(Visitor *v, void **obj)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    QObject *value = qobject_output_pop(qov, obj);
+    assert(qobject_type(value) == QTYPE_QLIST);
+}
+
+static bool qobject_output_type_int64(Visitor *v, const char *name,
+                                      int64_t *obj, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    qobject_output_add(qov, name, qnum_from_int(*obj));
+    return true;
+}
+
+static bool qobject_output_type_uint64(Visitor *v, const char *name,
+                                       uint64_t *obj, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    qobject_output_add(qov, name, qnum_from_uint(*obj));
+    return true;
+}
+
+static bool qobject_output_type_bool(Visitor *v, const char *name, bool *obj,
+                                     Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    qobject_output_add(qov, name, qbool_from_bool(*obj));
+    return true;
+}
+
+static bool qobject_output_type_str(Visitor *v, const char *name, char **obj,
+                                    Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    if (*obj) {
+        qobject_output_add(qov, name, qstring_from_str(*obj));
+    } else {
+        qobject_output_add(qov, name, qstring_from_str(""));
+    }
+    return true;
+}
+
+static bool qobject_output_type_number(Visitor *v, const char *name,
+                                       double *obj, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    qobject_output_add(qov, name, qnum_from_double(*obj));
+    return true;
+}
+
+static bool qobject_output_type_any(Visitor *v, const char *name,
+                                    QObject **obj, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+
+    qobject_output_add_obj(qov, name, qobject_ref(*obj));
+    return true;
+}
+
+static bool qobject_output_type_null(Visitor *v, const char *name,
+                                     QNull **obj, Error **errp)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    qobject_output_add(qov, name, qnull());
+    return true;
+}
+
+static bool qobject_output_policy_skip(Visitor *v, const char *name,
+                                       unsigned special_features)
+{
+    CompatPolicy *pol = &v->compat_policy;
+
+    return ((special_features & 1u << QAPI_DEPRECATED)
+            && pol->deprecated_output == COMPAT_POLICY_OUTPUT_HIDE)
+        || ((special_features & 1u << QAPI_UNSTABLE)
+            && pol->unstable_output == COMPAT_POLICY_OUTPUT_HIDE);
+}
+
+/* Finish building, and return the root object.
+ * The root object is never null. The caller becomes the object's
+ * owner, and should use qobject_unref() when done with it.  */
+static void qobject_output_complete(Visitor *v, void *opaque)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+
+    /* A visit must have occurred, with each start paired with end.  */
+    assert(qov->root && QSLIST_EMPTY(&qov->stack));
+    assert(opaque == qov->result);
+
+    *qov->result = qobject_ref(qov->root);
+    qov->result = NULL;
+}
+
+static void qobject_output_free(Visitor *v)
+{
+    QObjectOutputVisitor *qov = to_qov(v);
+    QStackEntry *e;
+
+    while (!QSLIST_EMPTY(&qov->stack)) {
+        e = QSLIST_FIRST(&qov->stack);
+        QSLIST_REMOVE_HEAD(&qov->stack, node);
+        g_free(e);
+    }
+
+    qobject_unref(qov->root);
+    g_free(qov);
+}
+
+Visitor *qobject_output_visitor_new(QObject **result)
+{
+    QObjectOutputVisitor *v;
+
+    v = g_malloc0(sizeof(*v));
+
+    v->visitor.type = VISITOR_OUTPUT;
+    v->visitor.start_struct = qobject_output_start_struct;
+    v->visitor.end_struct = qobject_output_end_struct;
+    v->visitor.start_list = qobject_output_start_list;
+    v->visitor.next_list = qobject_output_next_list;
+    v->visitor.end_list = qobject_output_end_list;
+    v->visitor.type_int64 = qobject_output_type_int64;
+    v->visitor.type_uint64 = qobject_output_type_uint64;
+    v->visitor.type_bool = qobject_output_type_bool;
+    v->visitor.type_str = qobject_output_type_str;
+    v->visitor.type_number = qobject_output_type_number;
+    v->visitor.type_any = qobject_output_type_any;
+    v->visitor.type_null = qobject_output_type_null;
+    v->visitor.policy_skip = qobject_output_policy_skip;
+    v->visitor.complete = qobject_output_complete;
+    v->visitor.free = qobject_output_free;
+
+    *result = NULL;
+    v->result = result;
+
+    return &v->visitor;
+}