struct rdline;
-typedef void (rdline_write_char_t)(struct rdline *rdl, char);
+typedef int (rdline_write_char_t)(struct rdline *rdl, char);
typedef void (rdline_validate_t)(struct rdline *rdl,
const char *buf, unsigned int size);
typedef int (rdline_complete_t)(struct rdline *rdl, const char *buf,