[gedit] ViewFrame: make the code more robust in case the start_mark is NULL

[Sébastien Wilmet <swilmet src gnome org>]

commit df0868201ebc66119d5130f7ae29e1b0cf47face
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed Jan 13 18:12:29 2016 +0100

    ViewFrame: make the code more robust in case the start_mark is NULL
    
    https://bugzilla.gnome.org/show_bug.cgi?id=760446

 gedit/gedit-view-frame.c |   44 +++++++++++++++++++++++++++-----------------
 1 files changed, 27 insertions(+), 17 deletions(-)
---
diff --git a/gedit/gedit-view-frame.c b/gedit/gedit-view-frame.c
index a7e686e..e54f32a 100644
--- a/gedit/gedit-view-frame.c
+++ b/gedit/gedit-view-frame.c
@@ -105,6 +105,25 @@ get_document (GeditViewFrame *frame)
 }
 
 static void
+get_iter_at_start_mark (GeditViewFrame *frame,
+                       GtkTextIter    *iter)
+{
+       GtkTextBuffer *buffer;
+
+       buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (frame->view));
+
+       if (frame->start_mark != NULL)
+       {
+               gtk_text_buffer_get_iter_at_mark (buffer, iter, frame->start_mark);
+       }
+       else
+       {
+               g_warn_if_reached ();
+               gtk_text_buffer_get_start_iter (buffer, iter);
+       }
+}
+
+static void
 gedit_view_frame_dispose (GObject *object)
 {
        GeditViewFrame *frame = GEDIT_VIEW_FRAME (object);
@@ -337,9 +356,8 @@ start_search_finished (GtkSourceSearchContext *search_context,
 static void
 start_search (GeditViewFrame *frame)
 {
-       GtkTextIter start_at;
-       GtkTextBuffer *buffer;
        GtkSourceSearchContext *search_context;
+       GtkTextIter start_at;
 
        g_return_if_fail (frame->search_mode == SEARCH);
 
@@ -350,11 +368,7 @@ start_search (GeditViewFrame *frame)
                return;
        }
 
-       buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (frame->view));
-
-       gtk_text_buffer_get_iter_at_mark (buffer,
-                                         &start_at,
-                                         frame->start_mark);
+       get_iter_at_start_mark (frame, &start_at);
 
        gtk_source_search_context_forward_async (search_context,
                                                 &start_at,
@@ -1056,11 +1070,7 @@ update_goto_line (GeditViewFrame *frame)
                return;
        }
 
-       doc = get_document (frame);
-
-       gtk_text_buffer_get_iter_at_mark (GTK_TEXT_BUFFER (doc),
-                                         &iter,
-                                         frame->start_mark);
+       get_iter_at_start_mark (frame, &iter);
 
        split_text = g_strsplit (entry_text, ":", -1);
 
@@ -1107,6 +1117,7 @@ update_goto_line (GeditViewFrame *frame)
 
        g_strfreev (split_text);
 
+       doc = get_document (frame);
        moved = gedit_document_goto_line (doc, line);
        moved_offset = gedit_document_goto_line_offset (doc, line, line_offset);
 
@@ -1200,17 +1211,13 @@ get_selected_text (GtkTextBuffer  *doc,
 static void
 init_search_entry (GeditViewFrame *frame)
 {
-       GtkTextBuffer *buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (frame->view));
-
        if (frame->search_mode == GOTO_LINE)
        {
                gint line;
                gchar *line_str;
                GtkTextIter iter;
 
-               gtk_text_buffer_get_iter_at_mark (buffer,
-                                                 &iter,
-                                                 frame->start_mark);
+               get_iter_at_start_mark (frame, &iter);
 
                line = gtk_text_iter_get_line (&iter);
 
@@ -1226,6 +1233,7 @@ init_search_entry (GeditViewFrame *frame)
        else
        {
                /* SEARCH mode */
+               GtkTextBuffer *buffer;
                gboolean selection_exists;
                gchar *search_text = NULL;
                gint selection_len = 0;
@@ -1248,6 +1256,8 @@ init_search_entry (GeditViewFrame *frame)
                        frame->old_search_text = g_strdup (frame->search_text);
                }
 
+               buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (frame->view));
+
                search_context = get_search_context (frame);
 
                if (search_context == NULL)