vf-metadata: fix handling of NULL metadata

lavfi would segfault due to a NULL dereference if it was asked for its
metadata and none had been allocated (oops). This happens for libav
which has no concept of filter metadata.

2 files changed, 23 insertions, 15 deletions

diff --git a/player/command.c b/player/command.c
index d938e48162..da978d2846 100644
--- a/player/command.c
+++ b/player/command.c
@@ -950,19 +950,24 @@ static int mp_property_vf_metadata(m_option_t *prop, int action, void *arg,
         char *rem;
         m_property_split_path(ka->key, &key, &rem);
         struct mp_tags vf_metadata;
-        if (vf_control_by_label(vf, VFCTRL_GET_METADATA, &vf_metadata, key)
-                == CONTROL_UNKNOWN)
+        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;
-
-        if (strlen(rem)) {
-            struct m_property_action_arg next_ka = *ka;
-            next_ka.key = rem;
-            return tag_property(prop, M_PROPERTY_KEY_ACTION, &next_ka,
-                                &vf_metadata);
-        } else {
-            return tag_property(prop, ka->action, ka->arg, &vf_metadata);
+        case CONTROL_OK:
+            if (strlen(rem)) {
+                struct m_property_action_arg next_ka = *ka;
+                next_ka.key = rem;
+                return tag_property(prop, M_PROPERTY_KEY_ACTION, &next_ka,
+                                    &vf_metadata);
+            } else {
+                return tag_property(prop, ka->action, ka->arg, &vf_metadata);
+            }
+            return M_PROPERTY_OK;
+        default:
+            return M_PROPERTY_ERROR;
         }
-        return M_PROPERTY_OK;
     }
     }
     return M_PROPERTY_NOT_IMPLEMENTED;
diff --git a/video/filter/vf_lavfi.c b/video/filter/vf_lavfi.c
index f2de4fe9a4..2002c97d16 100644
--- a/video/filter/vf_lavfi.c
+++ b/video/filter/vf_lavfi.c
@@ -334,10 +334,13 @@ static int control(vf_instance_t *vf, int request, void *data)
     case VFCTRL_SEEK_RESET:
         reset(vf);
         return CONTROL_OK;
-    case VFCTRL_GET_METADATA:{
-        *(struct mp_tags*) data = *vf->priv->metadata;
-        return CONTROL_OK;
-    }
+    case VFCTRL_GET_METADATA:
+      if (vf->priv && vf->priv->metadata) {
+          *(struct mp_tags*) data = *vf->priv->metadata;
+          return CONTROL_OK;
+      } else {
+          return CONTROL_NA;
+      }
     }
     return CONTROL_UNKNOWN;
 }