[gimp] Issue #3275 - Crash when opening an image after closing existing image

[Ell <ell src gnome org>]

commit b01113741e35f68e3a40b792e0daa2676f7eafd2
Author: Ell <ell_se yahoo com>
Date:   Sat Apr 20 14:30:43 2019 -0400

    Issue #3275 - Crash when opening an image after closing existing image
    
    In gimp_open_dialog_set_image(), use a weak pointer for storing the
    current image, to avoid a segfault in file_open_dialog_response()
    if the active image at the time of the open action has been closed
    before confirming the dialog.

 app/dialogs/file-open-dialog.c | 11 +++++++----
 app/widgets/gimpopendialog.c   | 38 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 6 deletions(-)
---
diff --git a/app/dialogs/file-open-dialog.c b/app/dialogs/file-open-dialog.c
index b28c07b08c..379cf12a72 100644
--- a/app/dialogs/file-open-dialog.c
+++ b/app/dialogs/file-open-dialog.c
@@ -139,10 +139,13 @@ file_open_dialog_response (GtkWidget *dialog,
         {
           if (! file_dialog->image)
             {
-              file_dialog->image = file_open_dialog_open_image (dialog,
-                                                                gimp,
-                                                                file,
-                                                                file_dialog->file_proc);
+              gimp_open_dialog_set_image (
+                open_dialog,
+                file_open_dialog_open_image (dialog,
+                                             gimp,
+                                             file,
+                                             file_dialog->file_proc),
+                TRUE);
 
               if (file_dialog->image)
                 {
diff --git a/app/widgets/gimpopendialog.c b/app/widgets/gimpopendialog.c
index 8a203935e9..7525ab1d7e 100644
--- a/app/widgets/gimpopendialog.c
+++ b/app/widgets/gimpopendialog.c
@@ -37,15 +37,25 @@
 #include "gimp-intl.h"
 
 
+/*  local function prototypes  */
+
+static void   gimp_open_dialog_dispose (GObject *object);
+
+
 G_DEFINE_TYPE (GimpOpenDialog, gimp_open_dialog,
                GIMP_TYPE_FILE_DIALOG)
 
 #define parent_class gimp_open_dialog_parent_class
 
 
+/*  private functions  */
+
 static void
 gimp_open_dialog_class_init (GimpOpenDialogClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = gimp_open_dialog_dispose;
 }
 
 static void
@@ -53,6 +63,14 @@ gimp_open_dialog_init (GimpOpenDialog *dialog)
 {
 }
 
+static void
+gimp_open_dialog_dispose (GObject *object)
+{
+  gimp_open_dialog_set_image (GIMP_OPEN_DIALOG (object), NULL, FALSE);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
 
 /*  public functions  */
 
@@ -83,9 +101,25 @@ gimp_open_dialog_set_image (GimpOpenDialog *dialog,
                             GimpImage      *image,
                             gboolean        open_as_layers)
 {
+  GimpFileDialog *file_dialog;
+
   g_return_if_fail (GIMP_IS_OPEN_DIALOG (dialog));
   g_return_if_fail (image == NULL || GIMP_IS_IMAGE (image));
 
-  GIMP_FILE_DIALOG (dialog)->image = image;
-  dialog->open_as_layers           = open_as_layers;
+  file_dialog = GIMP_FILE_DIALOG (dialog);
+
+  if (file_dialog->image)
+    {
+      g_object_remove_weak_pointer (G_OBJECT (file_dialog->image),
+                                    (gpointer *) &file_dialog->image);
+    }
+
+  file_dialog->image     = image;
+  dialog->open_as_layers = open_as_layers;
+
+  if (file_dialog->image)
+    {
+      g_object_add_weak_pointer (G_OBJECT (file_dialog->image),
+                                 (gpointer *) &file_dialog->image);
+    }
 }