[mutter] screen-cast/src: Make record functions return an error when failing

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 047da80c3b59abb233e50a788a50519bcfc20314
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Jul 3 16:57:01 2020 +0200

    screen-cast/src: Make record functions return an error when failing
    
    Now that we don't use the record function to early out depending on
    implicit state (don't record pixels if only cursor moved for example),
    let it simply report an error when it fails, as we should no longer ever
    return without pixels if nothing failed.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1361

 src/backends/meta-screen-cast-area-stream-src.c    | 18 ++++++------
 src/backends/meta-screen-cast-monitor-stream-src.c | 19 ++++++-------
 src/backends/meta-screen-cast-stream-src.c         | 32 ++++++++++++++--------
 src/backends/meta-screen-cast-stream-src.h         | 10 ++++---
 src/backends/meta-screen-cast-window-stream-src.c  | 16 +++++++----
 5 files changed, 53 insertions(+), 42 deletions(-)
---
diff --git a/src/backends/meta-screen-cast-area-stream-src.c b/src/backends/meta-screen-cast-area-stream-src.c
index e28d52b46f..f010d968d2 100644
--- a/src/backends/meta-screen-cast-area-stream-src.c
+++ b/src/backends/meta-screen-cast-area-stream-src.c
@@ -392,8 +392,9 @@ meta_screen_cast_area_stream_src_disable (MetaScreenCastStreamSrc *src)
 }
 
 static gboolean
-meta_screen_cast_area_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
-                                                   uint8_t                 *data)
+meta_screen_cast_area_stream_src_record_to_buffer (MetaScreenCastStreamSrc  *src,
+                                                   uint8_t                  *data,
+                                                   GError                  **error)
 {
   MetaScreenCastAreaStreamSrc *area_src =
     META_SCREEN_CAST_AREA_STREAM_SRC (src);
@@ -404,7 +405,6 @@ meta_screen_cast_area_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
   float scale;
   int stride;
   ClutterPaintFlag paint_flags = CLUTTER_PAINT_FLAG_NONE;
-  g_autoptr (GError) error = NULL;
 
   stage = get_stage (area_src);
   area = meta_screen_cast_area_stream_get_area (area_stream);
@@ -426,18 +426,16 @@ meta_screen_cast_area_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
                                       stride,
                                       CLUTTER_CAIRO_FORMAT_ARGB32,
                                       paint_flags,
-                                      &error))
-    {
-      g_warning ("Failed to record area: %s", error->message);
-      return FALSE;
-    }
+                                      error))
+    return FALSE;
 
   return TRUE;
 }
 
 static gboolean
-meta_screen_cast_area_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc *src,
-                                                        CoglFramebuffer         *framebuffer)
+meta_screen_cast_area_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc  *src,
+                                                        CoglFramebuffer          *framebuffer,
+                                                        GError                  **error)
 {
   MetaScreenCastAreaStreamSrc *area_src =
     META_SCREEN_CAST_AREA_STREAM_SRC (src);
diff --git a/src/backends/meta-screen-cast-monitor-stream-src.c 
b/src/backends/meta-screen-cast-monitor-stream-src.c
index 1aec6aaefd..760cb00e33 100644
--- a/src/backends/meta-screen-cast-monitor-stream-src.c
+++ b/src/backends/meta-screen-cast-monitor-stream-src.c
@@ -387,8 +387,9 @@ meta_screen_cast_monitor_stream_src_disable (MetaScreenCastStreamSrc *src)
 }
 
 static gboolean
-meta_screen_cast_monitor_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
-                                                      uint8_t                 *data)
+meta_screen_cast_monitor_stream_src_record_to_buffer (MetaScreenCastStreamSrc  *src,
+                                                      uint8_t                  *data,
+                                                      GError                  **error)
 {
   MetaScreenCastMonitorStreamSrc *monitor_src =
     META_SCREEN_CAST_MONITOR_STREAM_SRC (src);
@@ -405,8 +406,9 @@ meta_screen_cast_monitor_stream_src_record_to_buffer (MetaScreenCastStreamSrc *s
 }
 
 static gboolean
-meta_screen_cast_monitor_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc *src,
-                                                           CoglFramebuffer         *framebuffer)
+meta_screen_cast_monitor_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc  *src,
+                                                           CoglFramebuffer          *framebuffer,
+                                                           GError                  **error)
 {
   MetaScreenCastMonitorStreamSrc *monitor_src =
     META_SCREEN_CAST_MONITOR_STREAM_SRC (src);
@@ -430,7 +432,6 @@ meta_screen_cast_monitor_stream_src_record_to_framebuffer (MetaScreenCastStreamS
   for (l = meta_renderer_get_views (renderer); l; l = l->next)
     {
       ClutterStageView *view = CLUTTER_STAGE_VIEW (l->data);
-      g_autoptr (GError) error = NULL;
       CoglFramebuffer *view_framebuffer;
       MetaRectangle view_layout;
       int x, y;
@@ -451,12 +452,8 @@ meta_screen_cast_monitor_stream_src_record_to_framebuffer (MetaScreenCastStreamS
                                   x, y,
                                   cogl_framebuffer_get_width (view_framebuffer),
                                   cogl_framebuffer_get_height (view_framebuffer),
-                                  &error))
-        {
-          g_warning ("Error blitting view into DMABuf framebuffer: %s",
-                     error->message);
-          return FALSE;
-        }
+                                  error))
+        return FALSE;
     }
 
   cogl_framebuffer_finish (framebuffer);
diff --git a/src/backends/meta-screen-cast-stream-src.c b/src/backends/meta-screen-cast-stream-src.c
index 6addd16c46..7fe603b746 100644
--- a/src/backends/meta-screen-cast-stream-src.c
+++ b/src/backends/meta-screen-cast-stream-src.c
@@ -135,23 +135,25 @@ meta_screen_cast_stream_src_get_videocrop (MetaScreenCastStreamSrc *src,
 }
 
 static gboolean
-meta_screen_cast_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
-                                              uint8_t                 *data)
+meta_screen_cast_stream_src_record_to_buffer (MetaScreenCastStreamSrc  *src,
+                                              uint8_t                  *data,
+                                              GError                  **error)
 {
   MetaScreenCastStreamSrcClass *klass =
     META_SCREEN_CAST_STREAM_SRC_GET_CLASS (src);
 
-  return klass->record_to_buffer (src, data);
+  return klass->record_to_buffer (src, data, error);
 }
 
 static gboolean
-meta_screen_cast_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc *src,
-                                                   CoglFramebuffer         *framebuffer)
+meta_screen_cast_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc  *src,
+                                                   CoglFramebuffer          *framebuffer,
+                                                   GError                  **error)
 {
   MetaScreenCastStreamSrcClass *klass =
     META_SCREEN_CAST_STREAM_SRC_GET_CLASS (src);
 
-  return klass->record_to_framebuffer (src, framebuffer);
+  return klass->record_to_framebuffer (src, framebuffer, error);
 }
 
 static void
@@ -409,9 +411,10 @@ maybe_record_cursor (MetaScreenCastStreamSrc *src,
 }
 
 static gboolean
-do_record_frame (MetaScreenCastStreamSrc *src,
-                 struct spa_buffer       *spa_buffer,
-                 uint8_t                 *data)
+do_record_frame (MetaScreenCastStreamSrc  *src,
+                 struct spa_buffer        *spa_buffer,
+                 uint8_t                  *data,
+                 GError                  **error)
 {
   MetaScreenCastStreamSrcPrivate *priv =
     meta_screen_cast_stream_src_get_instance_private (src);
@@ -419,7 +422,7 @@ do_record_frame (MetaScreenCastStreamSrc *src,
   if (spa_buffer->datas[0].data ||
       spa_buffer->datas[0].type == SPA_DATA_MemFd)
     {
-      return meta_screen_cast_stream_src_record_to_buffer (src, data);
+      return meta_screen_cast_stream_src_record_to_buffer (src, data, error);
     }
   else if (spa_buffer->datas[0].type == SPA_DATA_DmaBuf)
     {
@@ -430,9 +433,12 @@ do_record_frame (MetaScreenCastStreamSrc *src,
         cogl_dma_buf_handle_get_framebuffer (dmabuf_handle);
 
       return meta_screen_cast_stream_src_record_to_framebuffer (src,
-                                                                dmabuf_fbo);
+                                                                dmabuf_fbo,
+                                                                error);
     }
 
+  g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+               "Unknown SPA buffer type %u", spa_buffer->datas[0].type);
   return FALSE;
 }
 
@@ -447,6 +453,7 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
   struct spa_buffer *spa_buffer;
   uint8_t *data = NULL;
   uint64_t now_us;
+  g_autoptr (GError) error = NULL;
 
   now_us = g_get_monotonic_time ();
   if (priv->video_format.max_framerate.num > 0 &&
@@ -474,7 +481,7 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
 
   if (!(flags & META_SCREEN_CAST_RECORD_FLAG_CURSOR_ONLY))
     {
-      if (do_record_frame (src, spa_buffer, data))
+      if (do_record_frame (src, spa_buffer, data, &error))
         {
           struct spa_meta_region *spa_meta_video_crop;
 
@@ -505,6 +512,7 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc  *src,
         }
       else
         {
+          g_warning ("Failed to record screen cast frame: %s", error->message);
           spa_buffer->datas[0].chunk->size = 0;
         }
     }
diff --git a/src/backends/meta-screen-cast-stream-src.h b/src/backends/meta-screen-cast-stream-src.h
index e43e701c17..fe96605645 100644
--- a/src/backends/meta-screen-cast-stream-src.h
+++ b/src/backends/meta-screen-cast-stream-src.h
@@ -59,10 +59,12 @@ struct _MetaScreenCastStreamSrcClass
                       float                   *frame_rate);
   void (* enable) (MetaScreenCastStreamSrc *src);
   void (* disable) (MetaScreenCastStreamSrc *src);
-  gboolean (* record_to_buffer) (MetaScreenCastStreamSrc *src,
-                                 uint8_t                 *data);
-  gboolean (* record_to_framebuffer) (MetaScreenCastStreamSrc *src,
-                                      CoglFramebuffer         *framebuffer);
+  gboolean (* record_to_buffer) (MetaScreenCastStreamSrc  *src,
+                                 uint8_t                  *data,
+                                 GError                  **error);
+  gboolean (* record_to_framebuffer) (MetaScreenCastStreamSrc  *src,
+                                      CoglFramebuffer          *framebuffer,
+                                      GError                  **error);
   gboolean (* get_videocrop) (MetaScreenCastStreamSrc *src,
                               MetaRectangle           *crop_rect);
   void (* set_cursor_metadata) (MetaScreenCastStreamSrc *src,
diff --git a/src/backends/meta-screen-cast-window-stream-src.c 
b/src/backends/meta-screen-cast-window-stream-src.c
index dfc5baa1a2..a504bd1949 100644
--- a/src/backends/meta-screen-cast-window-stream-src.c
+++ b/src/backends/meta-screen-cast-window-stream-src.c
@@ -457,8 +457,9 @@ meta_screen_cast_window_stream_src_disable (MetaScreenCastStreamSrc *src)
 }
 
 static gboolean
-meta_screen_cast_window_stream_src_record_to_buffer (MetaScreenCastStreamSrc *src,
-                                                     uint8_t                 *data)
+meta_screen_cast_window_stream_src_record_to_buffer (MetaScreenCastStreamSrc  *src,
+                                                     uint8_t                  *data,
+                                                     GError                  **error)
 {
   MetaScreenCastWindowStreamSrc *window_src =
     META_SCREEN_CAST_WINDOW_STREAM_SRC (src);
@@ -469,8 +470,9 @@ meta_screen_cast_window_stream_src_record_to_buffer (MetaScreenCastStreamSrc *sr
 }
 
 static gboolean
-meta_screen_cast_window_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc *src,
-                                                          CoglFramebuffer         *framebuffer)
+meta_screen_cast_window_stream_src_record_to_framebuffer (MetaScreenCastStreamSrc  *src,
+                                                          CoglFramebuffer          *framebuffer,
+                                                          GError                  **error)
 {
   MetaScreenCastWindowStreamSrc *window_src =
     META_SCREEN_CAST_WINDOW_STREAM_SRC (src);
@@ -485,7 +487,11 @@ meta_screen_cast_window_stream_src_record_to_framebuffer (MetaScreenCastStreamSr
   if (!meta_screen_cast_window_blit_to_framebuffer (window_src->screen_cast_window,
                                                     &stream_rect,
                                                     framebuffer))
-    return FALSE;
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Failed to blit window content to framebuffer");
+      return FALSE;
+    }
 
   stream = meta_screen_cast_stream_src_get_stream (src);
   switch (meta_screen_cast_stream_get_cursor_mode (stream))