- * the contents of old strings. Use ASAN in your tests, and pay extra
- * attention to failure paths.
+ * the contents of old strings. If you're lucky you'll get a segfault,
+ * because the kernel is only required to fault in new pages on write
+ * access. MSAN should be able to catch problems in the common case that
+ * the string or vector wasn't previously shrunk.
+ *
+ * Pay extra attention to your failure paths. For example, if you try
+ * to read directly into a caller-provided string, make sure to clear
+ * the string when you get an I/O error.