3 files changed, 141 insertions, 1 deletions
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 0cac6d707a..d25ff483eb 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -2,6 +2,7 @@ common-obj-y += migration.o tcp.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
 common-obj-y += xbzrle.o postcopy-ram.o
+common-obj-y += qjson.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
 common-obj-$(CONFIG_POSIX) += exec.o unix.o fd.o
diff --git a/migration/qjson.c b/migration/qjson.c
new file mode 100644
index 0000000000..cb479fe0eb
--- /dev/null
+++ b/migration/qjson.c
@@ -0,0 +1,140 @@
+/*
+ * A simple JSON writer
+ *
+ * Copyright Alexander Graf
+ *
+ * Authors:
+ *  Alexander Graf <agraf@suse.de>
+ *
+ * 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.
+ *
+ */
+
+/*
+ * Type QJSON lets you build JSON text.  Its interface mirrors (a
+ * subset of) abstract JSON syntax.
+ *
+ * It does *not* detect incorrect use.  It happily produces invalid
+ * JSON then.  This is what migration wants.
+ *
+ * QAPI output visitors also produce JSON text.  However, they do
+ * assert their preconditions and invariants, and therefore abort on
+ * incorrect use.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/qmp/qstring.h"
+#include "migration/qjson.h"
+#include "qemu/module.h"
+#include "qom/object.h"
+
+struct QJSON {
+    Object obj;
+    QString *str;
+    bool omit_comma;
+};
+
+#define QJSON(obj) OBJECT_CHECK(QJSON, (obj), TYPE_QJSON)
+
+static void json_emit_element(QJSON *json, const char *name)
+{
+    /* Check whether we need to print a , before an element */
+    if (json->omit_comma) {
+        json->omit_comma = false;
+    } else {
+        qstring_append(json->str, ", ");
+    }
+
+    if (name) {
+        qstring_append(json->str, "\"");
+        qstring_append(json->str, name);
+        qstring_append(json->str, "\" : ");
+    }
+}
+
+void json_start_object(QJSON *json, const char *name)
+{
+    json_emit_element(json, name);
+    qstring_append(json->str, "{ ");
+    json->omit_comma = true;
+}
+
+void json_end_object(QJSON *json)
+{
+    qstring_append(json->str, " }");
+    json->omit_comma = false;
+}
+
+void json_start_array(QJSON *json, const char *name)
+{
+    json_emit_element(json, name);
+    qstring_append(json->str, "[ ");
+    json->omit_comma = true;
+}
+
+void json_end_array(QJSON *json)
+{
+    qstring_append(json->str, " ]");
+    json->omit_comma = false;
+}
+
+void json_prop_int(QJSON *json, const char *name, int64_t val)
+{
+    json_emit_element(json, name);
+    qstring_append_int(json->str, val);
+}
+
+void json_prop_str(QJSON *json, const char *name, const char *str)
+{
+    json_emit_element(json, name);
+    qstring_append_chr(json->str, '"');
+    qstring_append(json->str, str);
+    qstring_append_chr(json->str, '"');
+}
+
+const char *qjson_get_str(QJSON *json)
+{
+    return qstring_get_str(json->str);
+}
+
+QJSON *qjson_new(void)
+{
+    QJSON *json = QJSON(object_new(TYPE_QJSON));
+    return json;
+}
+
+void qjson_finish(QJSON *json)
+{
+    json_end_object(json);
+}
+
+static void qjson_initfn(Object *obj)
+{
+    QJSON *json = QJSON(obj);
+
+    json->str = qstring_from_str("{ ");
+    json->omit_comma = true;
+}
+
+static void qjson_finalizefn(Object *obj)
+{
+    QJSON *json = QJSON(obj);
+
+    qobject_decref(QOBJECT(json->str));
+}
+
+static const TypeInfo qjson_type_info = {
+    .name = TYPE_QJSON,
+    .parent = TYPE_OBJECT,
+    .instance_size = sizeof(QJSON),
+    .instance_init = qjson_initfn,
+    .instance_finalize = qjson_finalizefn,
+};
+
+static void qjson_register_types(void)
+{
+    type_register_static(&qjson_type_info);
+}
+
+type_init(qjson_register_types)
diff --git a/migration/vmstate.c b/migration/vmstate.c
index bf3d5db301..46dc55ea40 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -6,7 +6,6 @@
 #include "qemu/bitops.h"
 #include "qemu/error-report.h"
 #include "trace.h"
-#include "qjson.h"
 
 static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
                                     void *opaque, QJSON *vmdesc);