+
+/* Copy the content of a string to tainted memory */
+static void
+gstring_rebuffer(gstring * g)
+{
+uschar * s = store_get(g->size, TRUE);
+memcpy(s, g->s, g->ptr);
+g->s = s;
+}
+
+
+
+/* Build or append to a growing-string, sprintf-style.
+
+If the "extend" flag is true, the string passed in can be NULL,
+empty, or non-empty. Growing is subject to an overall limit given
+by the size_limit argument.
+
+If the "extend" flag is false, the string passed in may not be NULL,
+will not be grown, and is usable in the original place after return.
+The return value can be NULL to signify overflow.
+
+Returns the possibly-new (if copy for growth was needed) string,
+not nul-terminated.
+*/
+
+gstring *
+string_vformat_trc(gstring * g, const uschar * func, unsigned line,
+ unsigned size_limit, unsigned flags, const char *format, va_list ap)