util: Introduce virObjectGetRWLockableObj

Introduce a helper to handle the error path more cleanly. The same
as virObjectGetLockableObj in order to essentially follow the original
logic of commit 'b545f65d' to ensure that the input argument at least
has some validity before using.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virobject.c

@@ -383,6 +383,22 @@ virObjectGetLockableObj(void *anyobj)
 }
 
 
+static virObjectRWLockablePtr
+virObjectGetRWLockableObj(void *anyobj)
+{
+    virObjectPtr obj;
+
+    if (virObjectIsClass(anyobj, virObjectRWLockableClass))
+        return anyobj;
+
+    obj = anyobj;
+    VIR_WARN("Object %p (%s) is not a virObjectRWLockable instance",
+              anyobj, obj ? obj->klass->name : "(unknown)");
+
+    return NULL;
+}
+
+
 /**
  * virObjectLock:
  * @anyobj: any instance of virObjectLockable or virObjectRWLockable
@@ -427,14 +443,12 @@ virObjectLock(void *anyobj)
 void
 virObjectRWLockRead(void *anyobj)
 {
-    if (virObjectIsClass(anyobj, virObjectRWLockableClass)) {
-        virObjectRWLockablePtr obj = anyobj;
-        virRWLockRead(&obj->lock);
-    } else {
-        virObjectPtr obj = anyobj;
-        VIR_WARN("Object %p (%s) is not a virObjectRWLockable instance",
-                 anyobj, obj ? obj->klass->name : "(unknown)");
-    }
+    virObjectRWLockablePtr obj = virObjectGetRWLockableObj(anyobj);
+
+    if (!obj)
+        return;
+
+    virRWLockRead(&obj->lock);
 }
 
 
@@ -458,14 +472,12 @@ virObjectRWLockRead(void *anyobj)
 void
 virObjectRWLockWrite(void *anyobj)
 {
-    if (virObjectIsClass(anyobj, virObjectRWLockableClass)) {
-        virObjectRWLockablePtr obj = anyobj;
-        virRWLockWrite(&obj->lock);
-    } else {
-        virObjectPtr obj = anyobj;
-        VIR_WARN("Object %p (%s) is not a virObjectRWLockable instance",
-                 anyobj, obj ? obj->klass->name : "(unknown)");
-    }
+    virObjectRWLockablePtr obj = virObjectGetRWLockableObj(anyobj);
+
+    if (!obj)
+        return;
+
+    virRWLockWrite(&obj->lock);
 }