qbool: Make conversion from QObject * accept null

qobject_to_qbool() crashes on null, which is a trap for the unwary.
Return null instead, and simplify a few callers.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1444918537-18107-3-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>

2 files changed, 5 insertions, 10 deletions

diff --git a/qobject/qbool.c b/qobject/qbool.c
index 5ff69f0..bc6535f 100644
--- a/qobject/qbool.c
+++ b/qobject/qbool.c
@@ -51,9 +51,9 @@ bool qbool_get_bool(const QBool *qb)
  */
 QBool *qobject_to_qbool(const QObject *obj)
 {
-    if (qobject_type(obj) != QTYPE_QBOOL)
+    if (!obj || qobject_type(obj) != QTYPE_QBOOL) {
         return NULL;
-
+    }
     return container_of(obj, QBool, base);
 }
 
diff --git a/qobject/qdict.c b/qobject/qdict.c
index 67b1a58..f179f4e 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -243,8 +243,7 @@ int64_t qdict_get_int(const QDict *qdict, const char *key)
  */
 bool qdict_get_bool(const QDict *qdict, const char *key)
 {
-    QObject *obj = qdict_get_obj(qdict, key, QTYPE_QBOOL);
-    return qbool_get_bool(qobject_to_qbool(obj));
+    return qbool_get_bool(qobject_to_qbool(qdict_get(qdict, key)));
 }
 
 /**
@@ -316,13 +315,9 @@ int64_t qdict_get_try_int(const QDict *qdict, const char *key,
  */
 bool qdict_get_try_bool(const QDict *qdict, const char *key, bool def_value)
 {
-    QObject *obj;
-
-    obj = qdict_get(qdict, key);
-    if (!obj || qobject_type(obj) != QTYPE_QBOOL)
-        return def_value;
+    QBool *qbool = qobject_to_qbool(qdict_get(qdict, key));
 
-    return qbool_get_bool(qobject_to_qbool(obj));
+    return qbool ? qbool_get_bool(qbool) : def_value;
 }
 
 /**