extern size_t log_info(const char *format, ...) __attribute__ ((__format__ (__printf__, 1, 2)));
extern size_t __log_buf(struct buf_output *, const char *format, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
extern size_t log_valist(const char *str, va_list);
+extern void log_prevalist(int type, const char *str, va_list);
extern size_t log_info_buf(const char *buf, size_t len);
extern int log_info_flush(void);