GLib source id wrap around

[Max Krasnyansky <maxk qualcomm com>]

Folks,

Sorry of this has been discussed before.
It seems to me that source id wrap around is not handled properly.
After looking at the source of g_source attach() it was pretty clear 
to me that return 0 means failure. However source id is allocated
by simply incrementing context->next_id, which is unsigned int and is 
initialized to 1. So eventually it will wrap around and become zero.
Am I missing something here ?

Here is the relevant portion of g_source_attach()
/**
 * ...
 * Return value: the ID for the source within the #GMainContext
 **/
guint
g_source_attach (GSource      *source,
                 GMainContext *context)
{
  guint result = 0;
  GSList *tmp_list;

  g_return_val_if_fail (source->context == NULL, 0);
  g_return_val_if_fail (!SOURCE_DESTROYED (source), 0);
  
  if (!context)
    context = g_main_context_default ();

  LOCK_CONTEXT (context);

  source->context = context;
  result = source->source_id = context->next_id++;

  ...

  return result;
}
(latest CVS. HEAD branch.)

I'd say we need to add something like following to that function.
        /* Handle wrap around. id 0 is invalid */
        if (!context->next_id)
                context->next_id = 1;

--

Also it looks like some glib functions don't bother checking for errors ;-).
For example g_source_new() does
          source = (GSource*) g_malloc0 (struct_size);

          source->source_funcs = source_funcs;
g_malloc0() can fail and return NULL.

Thanks

Max

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