extern char *xstrdup(const char *s);
extern int PRINTF(2, 3) xasprintf(char **strp, const char *fmt, ...);
+extern int PRINTF(2, 3) xasprintf_append(char **strp, const char *fmt, ...);
+extern int xavsprintf_append(char **strp, const char *fmt, va_list ap);
extern char *join_path(const char *path, const char *name);
/**