core: make sure objects retrieved with g_object_get() are valid in the ifaces

The interfaces usually retrieve objects (e.g. skeletons) from the Modem object
using g_object_get(), but we didn't make sure that these objects were actually
valid before using them.

This should clean up errors happening when the modem gets unplugged and still
some actions are ongoing.

Should fix https://bugzilla.gnome.org/show_bug.cgi?id=685933

1 files changed, 75 insertions, 94 deletions

diff --git a/src/mm-iface-modem-location.c b/src/mm-iface-modem-location.c
index d6e897c2..6009fd12 100644
--- a/src/mm-iface-modem-location.c
+++ b/src/mm-iface-modem-location.c
@@ -379,7 +379,8 @@ update_location_source_status (MMIfaceModemLocation *self,
     g_object_get (self,
                   MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &skeleton,
                   NULL);
-    g_assert (skeleton != NULL);
+    if (!skeleton)
+        return;
 
     /* Update status in the interface */
     mask = mm_gdbus_modem_location_get_enabled (skeleton);
@@ -440,7 +441,8 @@ setup_gathering_context_complete_and_free (SetupGatheringContext *ctx)
 {
     g_simple_async_result_complete_in_idle (ctx->result);
     g_object_unref (ctx->result);
-    g_object_unref (ctx->skeleton);
+    if (ctx->skeleton)
+        g_object_unref (ctx->skeleton);
     g_object_unref (ctx->self);
     g_free (ctx);
 }
@@ -598,7 +600,14 @@ setup_gathering (MMIfaceModemLocation *self,
     g_object_get (self,
                   MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
                   NULL);
-    g_assert (ctx->skeleton != NULL);
+    if (!ctx->skeleton) {
+        g_simple_async_result_set_error (ctx->result,
+                                         MM_CORE_ERROR,
+                                         MM_CORE_ERROR_FAILED,
+                                         "Couldn't get interface skeleton");
+        setup_gathering_context_complete_and_free (ctx);
+        return;
+    }
 
     /* Get current list of enabled sources */
     currently_enabled = mm_gdbus_modem_location_get_enabled (ctx->skeleton);
@@ -880,35 +889,14 @@ struct _DisablingContext {
     MmGdbusModemLocation *skeleton;
 };
 
-static DisablingContext *
-disabling_context_new (MMIfaceModemLocation *self,
-                       GAsyncReadyCallback callback,
-                       gpointer user_data)
-{
-    DisablingContext *ctx;
-
-    ctx = g_new0 (DisablingContext, 1);
-    ctx->self = g_object_ref (self);
-    ctx->result = g_simple_async_result_new (G_OBJECT (self),
-                                             callback,
-                                             user_data,
-                                             disabling_context_new);
-    ctx->step = DISABLING_STEP_FIRST;
-    g_object_get (ctx->self,
-                  MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
-                  NULL);
-    g_assert (ctx->skeleton != NULL);
-
-    return ctx;
-}
-
 static void
 disabling_context_complete_and_free (DisablingContext *ctx)
 {
     g_simple_async_result_complete_in_idle (ctx->result);
     g_object_unref (ctx->self);
     g_object_unref (ctx->result);
-    g_object_unref (ctx->skeleton);
+    if (ctx->skeleton)
+        g_object_unref (ctx->skeleton);
     g_free (ctx);
 }
 
@@ -969,9 +957,28 @@ mm_iface_modem_location_disable (MMIfaceModemLocation *self,
                                  GAsyncReadyCallback callback,
                                  gpointer user_data)
 {
-    interface_disabling_step (disabling_context_new (self,
-                                                     callback,
-                                                     user_data));
+    DisablingContext *ctx;
+
+    ctx = g_new0 (DisablingContext, 1);
+    ctx->self = g_object_ref (self);
+    ctx->result = g_simple_async_result_new (G_OBJECT (self),
+                                             callback,
+                                             user_data,
+                                             mm_iface_modem_location_disable);
+    ctx->step = DISABLING_STEP_FIRST;
+    g_object_get (ctx->self,
+                  MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
+                  NULL);
+    if (!ctx->skeleton) {
+        g_simple_async_result_set_error (ctx->result,
+                                         MM_CORE_ERROR,
+                                         MM_CORE_ERROR_FAILED,
+                                         "Couldn't get interface skeleton");
+        disabling_context_complete_and_free (ctx);
+        return;
+    }
+
+    interface_disabling_step (ctx);
 }
 
 /*****************************************************************************/
@@ -993,30 +1000,6 @@ struct _EnablingContext {
     MmGdbusModemLocation *skeleton;
 };
 
-static EnablingContext *
-enabling_context_new (MMIfaceModemLocation *self,
-                      GCancellable *cancellable,
-                      GAsyncReadyCallback callback,
-                      gpointer user_data)
-{
-    EnablingContext *ctx;
-
-    ctx = g_new0 (EnablingContext, 1);
-    ctx->self = g_object_ref (self);
-    ctx->cancellable = g_object_ref (cancellable);
-    ctx->result = g_simple_async_result_new (G_OBJECT (self),
-                                             callback,
-                                             user_data,
-                                             enabling_context_new);
-    ctx->step = ENABLING_STEP_FIRST;
-    g_object_get (ctx->self,
-                  MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
-                  NULL);
-    g_assert (ctx->skeleton != NULL);
-
-    return ctx;
-}
-
 static void
 enabling_context_complete_and_free (EnablingContext *ctx)
 {
@@ -1024,7 +1007,8 @@ enabling_context_complete_and_free (EnablingContext *ctx)
     g_object_unref (ctx->self);
     g_object_unref (ctx->result);
     g_object_unref (ctx->cancellable);
-    g_object_unref (ctx->skeleton);
+    if (ctx->skeleton)
+        g_object_unref (ctx->skeleton);
     g_free (ctx);
 }
 
@@ -1111,10 +1095,29 @@ mm_iface_modem_location_enable (MMIfaceModemLocation *self,
                                 GAsyncReadyCallback callback,
                                 gpointer user_data)
 {
-    interface_enabling_step (enabling_context_new (self,
-                                                   cancellable,
-                                                   callback,
-                                                   user_data));
+    EnablingContext *ctx;
+
+    ctx = g_new0 (EnablingContext, 1);
+    ctx->self = g_object_ref (self);
+    ctx->cancellable = g_object_ref (cancellable);
+    ctx->result = g_simple_async_result_new (G_OBJECT (self),
+                                             callback,
+                                             user_data,
+                                             mm_iface_modem_location_enable);
+    ctx->step = ENABLING_STEP_FIRST;
+    g_object_get (ctx->self,
+                  MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
+                  NULL);
+    if (!ctx->skeleton) {
+        g_simple_async_result_set_error (ctx->result,
+                                         MM_CORE_ERROR,
+                                         MM_CORE_ERROR_FAILED,
+                                         "Couldn't get interface skeleton");
+        enabling_context_complete_and_free (ctx);
+        return;
+    }
+
+    interface_enabling_step (ctx);
 }
 
 /*****************************************************************************/
@@ -1138,30 +1141,6 @@ struct _InitializationContext {
     MMModemLocationSource capabilities;
 };
 
-static InitializationContext *
-initialization_context_new (MMIfaceModemLocation *self,
-                            GCancellable *cancellable,
-                            GAsyncReadyCallback callback,
-                            gpointer user_data)
-{
-    InitializationContext *ctx;
-
-    ctx = g_new0 (InitializationContext, 1);
-    ctx->self = g_object_ref (self);
-    ctx->capabilities = MM_MODEM_LOCATION_SOURCE_NONE;
-    ctx->cancellable = g_object_ref (cancellable);
-    ctx->result = g_simple_async_result_new (G_OBJECT (self),
-                                             callback,
-                                             user_data,
-                                             initialization_context_new);
-    ctx->step = INITIALIZATION_STEP_FIRST;
-    g_object_get (ctx->self,
-                  MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &ctx->skeleton,
-                  NULL);
-    g_assert (ctx->skeleton != NULL);
-    return ctx;
-}
-
 static void
 initialization_context_complete_and_free (InitializationContext *ctx)
 {
@@ -1279,9 +1258,6 @@ mm_iface_modem_location_initialize_finish (MMIfaceModemLocation *self,
                                            GAsyncResult *res,
                                            GError **error)
 {
-    g_return_val_if_fail (MM_IS_IFACE_MODEM_LOCATION (self), FALSE);
-    g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
-
     return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
 }
 
@@ -1291,10 +1267,9 @@ mm_iface_modem_location_initialize (MMIfaceModemLocation *self,
                                     GAsyncReadyCallback callback,
                                     gpointer user_data)
 {
+    InitializationContext *ctx;
     MmGdbusModemLocation *skeleton = NULL;
 
-    g_return_if_fail (MM_IS_IFACE_MODEM_LOCATION (self));
-
     /* Did we already create it? */
     g_object_get (self,
                   MM_IFACE_MODEM_LOCATION_DBUS_SKELETON, &skeleton,
@@ -1315,18 +1290,24 @@ mm_iface_modem_location_initialize (MMIfaceModemLocation *self,
     }
 
     /* Perform async initialization here */
-    interface_initialization_step (initialization_context_new (self,
-                                                               cancellable,
-                                                               callback,
-                                                               user_data));
-    g_object_unref (skeleton);
+
+    ctx = g_new0 (InitializationContext, 1);
+    ctx->self = g_object_ref (self);
+    ctx->capabilities = MM_MODEM_LOCATION_SOURCE_NONE;
+    ctx->cancellable = g_object_ref (cancellable);
+    ctx->result = g_simple_async_result_new (G_OBJECT (self),
+                                             callback,
+                                             user_data,
+                                             mm_iface_modem_location_initialize);
+    ctx->step = INITIALIZATION_STEP_FIRST;
+    ctx->skeleton = skeleton;
+
+    interface_initialization_step (ctx);
 }
 
 void
 mm_iface_modem_location_shutdown (MMIfaceModemLocation *self)
 {
-    g_return_if_fail (MM_IS_IFACE_MODEM_LOCATION (self));
-
     /* Unexport DBus interface and remove the skeleton */
     mm_gdbus_object_skeleton_set_modem_location (MM_GDBUS_OBJECT_SKELETON (self), NULL);
     g_object_set (self,