[mutter/gnome-3-28] screen-cast: Handle PipeWire errors more gracefully

[Jonas Ådahl <jadahl src gnome org>]

commit 32f02010ae9dea528c3f601b47bccc98f53dbcd2
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu May 3 16:07:22 2018 +0200

    screen-cast: Handle PipeWire errors more gracefully
    
    Various code assumed PipeWire function calls would never fail. Some can
    actually fail for real reasons, and some currently can only fail due to
    OOM situations, but we should still not assume that will always be the
    case.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/102
    
    
    (cherry picked from commit 0f9c6aef99b223a6f520071d640cf34c92046f7a)

 src/backends/meta-screen-cast-stream-src.c | 39 +++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 6 deletions(-)
---
diff --git a/src/backends/meta-screen-cast-stream-src.c b/src/backends/meta-screen-cast-stream-src.c
index 744d116a6..337755002 100644
--- a/src/backends/meta-screen-cast-stream-src.c
+++ b/src/backends/meta-screen-cast-stream-src.c
@@ -153,6 +153,11 @@ meta_screen_cast_stream_src_maybe_record_frame (MetaScreenCastStreamSrc *src)
     return;
 
   buffer = pw_stream_peek_buffer (priv->pipewire_stream, buffer_id);
+  if (!buffer)
+    {
+      g_warning ("Failed to peek at PipeWire buffer");
+      return;
+    }
 
   if (buffer->datas[0].type == priv->pipewire_type->data.MemFd)
     {
@@ -327,10 +332,18 @@ create_pipewire_stream (MetaScreenCastStreamSrc  *src,
   struct spa_fraction max_framerate;
   struct spa_fraction min_framerate;
   const struct spa_pod *params[1];
+  int result;
 
   pipewire_stream = pw_stream_new (priv->pipewire_remote,
                                    "meta-screen-cast-src",
                                    NULL);
+  if (!pipewire_stream)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Failed to create PipeWire stream: %s",
+                   strerror (errno));
+      return NULL;
+    }
 
   meta_screen_cast_stream_src_get_specs (src, &width, &height, &frame_rate);
   frame_rate_fraction = meta_fraction_from_double (frame_rate);
@@ -356,14 +369,15 @@ create_pipewire_stream (MetaScreenCastStreamSrc  *src,
                           &stream_events,
                           src);
 
-  if (pw_stream_connect (pipewire_stream,
-                         PW_DIRECTION_OUTPUT,
-                         NULL,
-                         PW_STREAM_FLAG_NONE,
-                         params, G_N_ELEMENTS (params)) != 0)
+  result = pw_stream_connect (pipewire_stream,
+                              PW_DIRECTION_OUTPUT,
+                              NULL,
+                              PW_STREAM_FLAG_NONE,
+                              params, G_N_ELEMENTS (params));
+  if (result != 0)
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                   "Could not connect");
+                   "Could not connect: %s", spa_strerror (result));
       return NULL;
     }
 
@@ -466,6 +480,12 @@ create_pipewire_source (void)
     (MetaPipeWireSource *) g_source_new (&pipewire_source_funcs,
                                          sizeof (MetaPipeWireSource));
   pipewire_source->pipewire_loop = pw_loop_new (NULL);
+  if (!pipewire_source->pipewire_loop)
+    {
+      g_source_destroy ((GSource *) pipewire_source);
+      return NULL;
+    }
+
   g_source_add_unix_fd (&pipewire_source->base,
                         pw_loop_get_fd (pipewire_source->pipewire_loop),
                         G_IO_IN | G_IO_ERR);
@@ -491,6 +511,13 @@ meta_screen_cast_stream_src_initable_init (GInitable     *initable,
     meta_screen_cast_stream_src_get_instance_private (src);
 
   priv->pipewire_source = create_pipewire_source ();
+  if (!priv->pipewire_source)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Failed to create PipeWire source");
+      return FALSE;
+    }
+
   priv->pipewire_core = pw_core_new (priv->pipewire_source->pipewire_loop,
                                      NULL);
   if (!priv->pipewire_core)