[gnome-software/gnome-3-16] screenshot image: Don't crash if we get a libsoup callback after dispose

[Kalev Lember <klember src gnome org>]

commit 645129074ddd589cbb2afd6b939c2eae6bb3ed35
Author: Kalev Lember <kalevlember gmail com>
Date:   Thu Jun 4 22:24:09 2015 +0200

    screenshot image: Don't crash if we get a libsoup callback after dispose
    
    If dispose has already run and we get a callback from libsoup, just
    return immediately, avoiding crashing down below due to cleared priv
    data. Since the priv->session pointer is cleared in destroy(), we can
    check if it's NULL to detect if dispose has already run.
    
    This should fully fix the crash reported in
    https://bugzilla.redhat.com/show_bug.cgi?id=1137027

 src/gs-screenshot-image.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)
---
diff --git a/src/gs-screenshot-image.c b/src/gs-screenshot-image.c
index 59479ae..7234fe6 100644
--- a/src/gs-screenshot-image.c
+++ b/src/gs-screenshot-image.c
@@ -230,15 +230,16 @@ gs_screenshot_image_complete_cb (SoupSession *session,
                                 SoupMessage *msg,
                                 gpointer user_data)
 {
-       GsScreenshotImagePrivate *priv;
+       _cleanup_object_unref_ GsScreenshotImage *ssimg = GS_SCREENSHOT_IMAGE (user_data);
+       GsScreenshotImagePrivate *priv = gs_screenshot_image_get_instance_private (ssimg);
        gboolean ret;
        _cleanup_error_free_ GError *error = NULL;
        _cleanup_object_unref_ AsImage *im = NULL;
        _cleanup_object_unref_ GdkPixbuf *pixbuf = NULL;
        _cleanup_object_unref_ GInputStream *stream = NULL;
-       _cleanup_object_unref_ GsScreenshotImage *ssimg = GS_SCREENSHOT_IMAGE (user_data);
 
-       if (msg->status_code == SOUP_STATUS_CANCELLED)
+       /* return immediately if the message was cancelled or if we're in destruction */
+       if (msg->status_code == SOUP_STATUS_CANCELLED || priv->session == NULL)
                return;
 
        if (msg->status_code != SOUP_STATUS_OK) {
@@ -249,8 +250,6 @@ gs_screenshot_image_complete_cb (SoupSession *session,
                return;
        }
 
-       priv = gs_screenshot_image_get_instance_private (ssimg);
-
        /* create a buffer with the data */
        stream = g_memory_input_stream_new_from_data (msg->response_body->data,
                                                      msg->response_body->length,