[Xcb] [PATCH:xcb-util] Make sure wm_class name strings are null-terminated

[Peter Harris]

On 2010-06-14 15:28, Alan Coopersmith wrote:
> 
> After digging into this more, I'm not sure if any patch is needed here.
> It depends on whether you want to expose bugs in other people's code, or
> protect API callers from them.
> 
> ICCCM says WM_CLASS contains two null-terminated strings.

How about something like:

(Completely untested. Not even compiled. For discussion only.)

diff --git a/icccm/icccm.c b/icccm/icccm.c
index 1c66a74..9ada18d 100644
--- a/icccm/icccm.c
+++ b/icccm/icccm.c
@@ -359,8 +359,17 @@ xcb_get_wm_class_from_reply
   prop->_reply = reply;
   prop->instance_name = (char *) xcb_get_property_value(prop->_reply);

+  int len = xcb_get_property_value_length(prop->_reply);
+  /* Ensure there's a C end-of-string at the end of the property.
+     Truncate the property if necessary (the spec says there's already
+     a 0 in the last position, so this only hurts invalid props). */
+  if(len < reply->length * 4)
+    prop->instance_name[len] = 0;
+  else
+    prop->instance_name[len-1] = 0;
+
   int name_len = strlen(prop->instance_name);
-  if(name_len == xcb_get_property_value_length(prop->_reply))
+  if(name_len == len)
     name_len--;

   prop->class_name = prop->instance_name + name_len + 1;
--
1.7.0.6

-- 
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Peter Harris                    http://connectivity.opentext.com/
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