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

1 files 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)