A quick way to fetch string from qobject when it's a QString.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/qapi/qmp/qstring.h |  1 +
 qobject/qstring.c          | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h
index 34278bd639..12ae4e1c29 100644
--- a/include/qapi/qmp/qstring.h
+++ b/include/qapi/qmp/qstring.h
@@ -28,6 +28,7 @@ QString *qstring_from_substr(const char *str, int start, int end);
 size_t qstring_get_length(const QString *qstring);
 const char *qstring_get_str(const QString *qstring);
 const char *qstring_get_try_str(const QString *qstring);
+const char *qobject_get_try_str(const QObject *qstring);
 void qstring_append_int(QString *qstring, int64_t value);
 void qstring_append(QString *qstring, const char *str);
 void qstring_append_chr(QString *qstring, int c);
diff --git a/qobject/qstring.c b/qobject/qstring.c
index 9df04e3c7b..bbe689a9e3 100644
--- a/qobject/qstring.c
+++ b/qobject/qstring.c
@@ -139,6 +139,17 @@ const char *qstring_get_try_str(const QString *qstring)
 }
 
 /**
+ * qobject_get_try_str(): Return a pointer of the backstore string
+ *
+ * NOTE: the string will only be returned if the object is valid, and
+ * its type is QString, otherwise NULL is returned.
+ */
+const char *qobject_get_try_str(const QObject *qstring)
+{
+    return qstring_get_try_str(qobject_to_qstring(qstring));
+}
+
+/**
  * qstring_destroy_obj(): Free all memory allocated by a QString
  * object
  */
-- 
2.13.5