qdict: Add qdict_{set,copy}_default()

In the block layer functions that determine options for a child block
device, it's a common pattern to either copy options from the parent's
options or to set a default string if the option isn't explicitly set
yet for the child. Provide convenience functions so that it becomes a
one-liner for each option.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
index d20db94..9fbf68e 100644
--- a/include/qapi/qmp/qdict.h
+++ b/include/qapi/qmp/qdict.h
@@ -65,6 +65,9 @@ int64_t qdict_get_try_int(const QDict *qdict, const char *key,
 int qdict_get_try_bool(const QDict *qdict, const char *key, int def_value);
 const char *qdict_get_try_str(const QDict *qdict, const char *key);
 
+void qdict_copy_default(QDict *dst, QDict *src, const char *key);
+void qdict_set_default_str(QDict *dst, const char *key, const char *val);
+
 QDict *qdict_clone_shallow(const QDict *src);
 void qdict_flatten(QDict *qdict);