bus/dir-watch: Do not crash with > 128 dirs

Without this running, dbus-daemon with long XDG_DATA_DIRS
will crash on out-of-bounds write:

	$ XDG_DATA_DIRS=$(seq  -f "/foo/%g" -s ':' 129) dbus-daemon --session
	*** stack smashing detected ***: terminated

2 files changed, 12 insertions, 2 deletions

diff --git a/bus/dir-watch-inotify.c b/bus/dir-watch-inotify.c
index b52a24c0..9beadb0e 100644
--- a/bus/dir-watch-inotify.c
+++ b/bus/dir-watch-inotify.c
@@ -108,12 +108,17 @@ _set_watched_dirs_internal (DBusList **directories)
 
   i = 0;
   link = _dbus_list_get_first_link (directories);
-  while (link != NULL)
+  while (link != NULL && i < MAX_DIRS_TO_WATCH)
     {
       new_dirs[i++] = (char *)link->data;
       link = _dbus_list_get_next_link (directories, link);
     }
 
+  if (link != NULL)
+    {
+      _dbus_warn ("Too many directories to watch them all, only watching first %d.", MAX_DIRS_TO_WATCH);
+    }
+
   /* Look for directories in both the old and new sets, if
    * we find one, move its data into the new set.
    */
diff --git a/bus/dir-watch-kqueue.c b/bus/dir-watch-kqueue.c
index 183db241..15519fcb 100644
--- a/bus/dir-watch-kqueue.c
+++ b/bus/dir-watch-kqueue.c
@@ -218,12 +218,17 @@ bus_set_watched_dirs (BusContext *context, DBusList **directories)
 
   i = 0;
   link = _dbus_list_get_first_link (directories);
-  while (link != NULL)
+  while (link != NULL && i < MAX_DIRS_TO_WATCH)
     {
       new_dirs[i++] = (char *)link->data;
       link = _dbus_list_get_next_link (directories, link);
     }
 
+  if (link != NULL)
+    {
+      _dbus_warn ("Too many directories to watch them all, only watching first %d.", MAX_DIRS_TO_WATCH);
+    }
+
   /* Look for directories in both the old and new sets, if
    * we find one, move its data into the new set.
    */