qfloat qint: Make conversion from QObject * accept null

qobject_to_qfloat() and qobject_to_qint() crash 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: <1444918537-18107-5-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>

3 files changed, 7 insertions, 12 deletions

diff --git a/qobject/qdict.c b/qobject/qdict.c
index 6b32285..97e881b 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -229,8 +229,7 @@ double qdict_get_double(const QDict *qdict, const char *key)
  */
 int64_t qdict_get_int(const QDict *qdict, const char *key)
 {
-    QObject *obj = qdict_get_obj(qdict, key, QTYPE_QINT);
-    return qint_get_int(qobject_to_qint(obj));
+    return qint_get_int(qobject_to_qint(qdict_get(qdict, key)));
 }
 
 /**
@@ -297,13 +296,9 @@ const char *qdict_get_str(const QDict *qdict, const char *key)
 int64_t qdict_get_try_int(const QDict *qdict, const char *key,
                           int64_t def_value)
 {
-    QObject *obj;
-
-    obj = qdict_get(qdict, key);
-    if (!obj || qobject_type(obj) != QTYPE_QINT)
-        return def_value;
+    QInt *qint = qobject_to_qint(qdict_get(qdict, key));
 
-    return qint_get_int(qobject_to_qint(obj));
+    return qint ? qint_get_int(qint) : def_value;
 }
 
 /**
diff --git a/qobject/qfloat.c b/qobject/qfloat.c
index 7de0992..c865163 100644
--- a/qobject/qfloat.c
+++ b/qobject/qfloat.c
@@ -51,9 +51,9 @@ double qfloat_get_double(const QFloat *qf)
  */
 QFloat *qobject_to_qfloat(const QObject *obj)
 {
-    if (qobject_type(obj) != QTYPE_QFLOAT)
+    if (!obj || qobject_type(obj) != QTYPE_QFLOAT) {
         return NULL;
-
+    }
     return container_of(obj, QFloat, base);
 }
 
diff --git a/qobject/qint.c b/qobject/qint.c
index 86b9b04..999688e 100644
--- a/qobject/qint.c
+++ b/qobject/qint.c
@@ -50,9 +50,9 @@ int64_t qint_get_int(const QInt *qi)
  */
 QInt *qobject_to_qint(const QObject *obj)
 {
-    if (qobject_type(obj) != QTYPE_QINT)
+    if (!obj || qobject_type(obj) != QTYPE_QINT) {
         return NULL;
-
+    }
     return container_of(obj, QInt, base);
 }