command: make empty vf-metadata not an error

If a filter exists, but has no metadata, just return success. This
allows the user to distinguish between no metadata available, and filter
not inserted.

See #1408.

2 files changed, 10 insertions, 14 deletions

diff --git a/player/command.c b/player/command.c
index b44d218f52..893bbd9a94 100644
--- a/player/command.c
+++ b/player/command.c
@@ -1034,8 +1034,10 @@ static int tag_property(int action, void *arg, struct mp_tags *tags)
             res = talloc_asprintf_append_buffer(res, "%s: %s\n",
                                                 tags->keys[n], tags->values[n]);
         }
+        if (!res)
+            res = talloc_strdup(NULL, "(empty)");
         *(char **)arg = res;
-        return res ? M_PROPERTY_OK : M_PROPERTY_UNAVAILABLE;
+        return M_PROPERTY_OK;
     }
     case M_PROPERTY_KEY_ACTION: {
         struct m_property_action_arg *ka = arg;
@@ -1102,22 +1104,16 @@ static int mp_property_vf_metadata(void *ctx, struct m_property *prop,
         return M_PROPERTY_UNAVAILABLE;
     struct vf_chain *vf = mpctx->d_video->vfilter;
 
-    switch(action) {
-    case M_PROPERTY_GET_TYPE:
-    case M_PROPERTY_GET:
-    case M_PROPERTY_GET_NODE:
-        return M_PROPERTY_NOT_IMPLEMENTED;
-    case M_PROPERTY_KEY_ACTION: {
+    if (action == M_PROPERTY_KEY_ACTION) {
         struct m_property_action_arg *ka = arg;
         bstr key;
         char *rem;
         m_property_split_path(ka->key, &key, &rem);
-        struct mp_tags vf_metadata;
+        struct mp_tags vf_metadata = {0};
         switch (vf_control_by_label(vf, VFCTRL_GET_METADATA, &vf_metadata, key)) {
-        case CONTROL_NA:
-            return M_PROPERTY_UNAVAILABLE;
         case CONTROL_UNKNOWN:
             return M_PROPERTY_UNKNOWN;
+        case CONTROL_NA: // empty
         case CONTROL_OK:
             if (strlen(rem)) {
                 struct m_property_action_arg next_ka = *ka;
@@ -1131,7 +1127,6 @@ static int mp_property_vf_metadata(void *ctx, struct m_property *prop,
             return M_PROPERTY_ERROR;
         }
     }
-    }
     return M_PROPERTY_NOT_IMPLEMENTED;
 }
 
diff --git a/video/filter/vf.c b/video/filter/vf.c
index 7a5b08bcd9..6a7c98aef2 100644
--- a/video/filter/vf.c
+++ b/video/filter/vf.c
@@ -174,10 +174,11 @@ int vf_control_by_label(struct vf_chain *c,int cmd, void *arg, bstr label)
     char *label_str = bstrdup0(NULL, label);
     struct vf_instance *cur = vf_find_by_label(c, label_str);
     talloc_free(label_str);
-    if (cur && cur->control)
-        return cur->control(cur, cmd, arg);
-    else
+    if (cur) {
+        return cur->control ? cur->control(cur, cmd, arg) : CONTROL_NA;
+    } else {
         return CONTROL_UNKNOWN;
+    }
 }
 
 static void vf_control_all(struct vf_chain *c, int cmd, void *arg)