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 <address@hidden>
---
include/qapi/qmp/qdict.h | 3 +++
qobject/qdict.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 37 insertions(+)
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);
diff --git a/qobject/qdict.c b/qobject/qdict.c
index 2fcb7fe..45ba42c 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -477,6 +477,40 @@ static void qdict_destroy_obj(QObject *obj)
g_free(qdict);
}
+/**
+ * qdict_copy_default(): If no entry mapped by 'key' exists in 'dst' yet, the
+ * value of 'key' in 'src' is copied there (and the refcount increased
+ * accordingly).
+ */
+void qdict_copy_default(QDict *dst, QDict *src, const char *key)
+{
+ QObject *val;
+
+ if (qdict_haskey(dst, key)) {
+ return;
+ }
+
+ val = qdict_get(src, key);
+ if (val) {
+ qobject_incref(val);
+ qdict_put_obj(dst, key, val);
+ }
+}
+
+/**
+ * qdict_set_default_str(): If no entry mapped by 'key' exists in 'dst' yet,
+ * 'val' is put there, with the QDict taking the reference. Otherwise, the
+ * refcount of 'val' is decreased.
+ */
+void qdict_set_default_str(QDict *dst, const char *key, const char *val)
+{
+ if (qdict_haskey(dst, key)) {
+ return;
+ }
+
+ qdict_put(dst, key, qstring_from_str(val));
+}
+
static void qdict_flatten_qdict(QDict *qdict, QDict *target,
const char *prefix);