* Add a buffer at head of the circular buffer. 'c' is a pointer to a
* buffer, and n is the number of char to add. Return the number of
* copied bytes on success, or a negative value on error.
*/
int cirbuf_add_buf_head(struct cirbuf *cbuf, const char *c, unsigned int n);
* Add a buffer at head of the circular buffer. 'c' is a pointer to a
* buffer, and n is the number of char to add. Return the number of
* copied bytes on success, or a negative value on error.
*/
int cirbuf_add_buf_head(struct cirbuf *cbuf, const char *c, unsigned int n);