+
+ Intermediate layers (eg. the string functions) can test for taint, and use this
+ for ensurinng that results have proper state. For example the
+ string_vformat_trc() routing supporting the string_sprintf() interface will
+ recopy a string being built into a tainted allocation if it meets a %s for a
+ tainted argument. Any intermediate-layer function that (can) return a new
+ allocation should behave this way; returning a tainted result if any tainted
+ content is used. Intermediate-layer functions (eg. Ustrncpy) that modify
+ existing allocations fail if tainted data is written into an untainted area.
+ Users of functions that modify existing allocations should check if a tainted
+ source and an untainted destination is used, and fail instead (sprintf() being
+ the classic case).