BGO#665549: add sanity-check of atk_text_get_text parameters

Have atk_text_get_text check that end_offset is either -1 or greater or
equal to the start offset before passing the query to the toolkit. Fixes
a gtk crash.

Also document that an end position of -1 to atk_text_get_text indicates the
end of the string

diff --git a/atk/atktext.c b/atk/atktext.c
index a1e90de..086dd18 100755 (executable)
--- a/atk/atktext.c
+++ b/atk/atktext.c
@@ -237,7 +237,7 @@ atk_text_base_init (AtkTextIface *class)
  * atk_text_get_text:
  * @text: an #AtkText
  * @start_offset: start position
- * @end_offset: end position
+ * @end_offset: end position, or -1 for the end of the string.
  *
  * Gets the specified text.
  *
@@ -255,7 +255,8 @@ atk_text_get_text (AtkText      *text,
 
   iface = ATK_TEXT_GET_IFACE (text);
 
-  if (start_offset < 0 || end_offset < -1)
+  if (start_offset < 0 || end_offset < -1 ||
+      (end_offset != -1 && end_offset < start_offset))
     return NULL;
 
   if (iface->get_text)