[mutter] screen-cast-stream: Use SPA_META_Header

[Marge Bot <marge-bot src gnome org>]

commit 30b5229e0eeb5117fe3061cfcc1d1e59c199f4d9
Author: columbarius <co1umbarius protonmail com>
Date:   Fri Jul 15 09:13:52 2022 +0200

    screen-cast-stream: Use SPA_META_Header
    
    With this header we can set a flag to signal that the whole buffer is
    corrupt and should be ignored. With this we can cater to all cases:
    * Window buffer fine, but cursor broken:
      Use the spa_meta_cursor properties like id or offset accordingly
    * Window buffer broken, but cursor fine:
      Use the chunk flags
    * Both are broken / the dequeued buffer is not usable
      Use the spa_meta_header flag
    
    Additionally clients can now check if a buffer contains spa_meta_header
    data and can thus only check for the new or the old behaviour.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2516>

 src/backends/meta-screen-cast-stream-src.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
---
diff --git a/src/backends/meta-screen-cast-stream-src.c b/src/backends/meta-screen-cast-stream-src.c
index d25d0c4277..8d0e449557 100644
--- a/src/backends/meta-screen-cast-stream-src.c
+++ b/src/backends/meta-screen-cast-stream-src.c
@@ -598,6 +598,7 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
   MetaRectangle crop_rect;
   struct pw_buffer *buffer;
   struct spa_buffer *spa_buffer;
+  struct spa_meta_header *header;
   uint8_t *data = NULL;
   uint64_t now_us;
   g_autoptr (GError) error = NULL;
@@ -640,9 +641,17 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
   spa_buffer = buffer->buffer;
   data = spa_buffer->datas[0].data;
 
+  header = spa_buffer_find_meta_data (spa_buffer,
+                                      SPA_META_Header,
+                                      sizeof (*header));
+
   if (spa_buffer->datas[0].type != SPA_DATA_DmaBuf && !data)
     {
       g_critical ("Invalid buffer data");
+      if (header)
+        header->flags = SPA_META_HEADER_FLAG_CORRUPTED;
+
+      pw_stream_queue_buffer (priv->pipewire_stream, buffer);
       return;
     }
 
@@ -700,6 +709,9 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
 
   priv->last_frame_timestamp_us = now_us;
 
+  if (header)
+    header->flags = 0;
+
   pw_stream_queue_buffer (priv->pipewire_stream, buffer);
 }
 
@@ -795,7 +807,7 @@ on_stream_param_changed (void                 *data,
   uint8_t params_buffer[1024];
   int32_t width, height, stride, size;
   struct spa_pod_builder pod_builder;
-  const struct spa_pod *params[3];
+  const struct spa_pod *params[4];
   const int bpp = 4;
   int buffer_types;
 
@@ -840,6 +852,12 @@ on_stream_param_changed (void                 *data,
     SPA_PARAM_META_type, SPA_POD_Id (SPA_META_Cursor),
     SPA_PARAM_META_size, SPA_POD_Int (CURSOR_META_SIZE (384, 384)));
 
+  params[3] = spa_pod_builder_add_object (
+    &pod_builder,
+    SPA_TYPE_OBJECT_ParamMeta, SPA_PARAM_Meta,
+    SPA_PARAM_META_type, SPA_POD_Id (SPA_META_Header),
+    SPA_PARAM_META_size, SPA_POD_Int (sizeof (struct spa_meta_header)));
+
   pw_stream_update_params (priv->pipewire_stream, params, G_N_ELEMENTS (params));
 
   if (klass->notify_params_updated)