+/* replace any %s with src, or appends " $src" */
+ssize_t m_file_fmt(char *dst, ssize_t n, const char *fmt, const char *src);
+int m_tempfd(char *dst, ssize_t n, const char *dir, const char *fmt);
+FILE *m_tempfile(char *dst, ssize_t n, const char *dir, const char *fmt);
+