Function msgbuf_addstr

freebsd/kern/subr_msgbuf.c:183–284

* Append a NUL-terminated string with a priority to a message buffer. * Filter carriage returns if the caller requests it. * * XXX The carriage return filtering behavior is present in the * msglogchar() API, however testing has shown that we don't seem to send * carriage returns down this path. So do we still need it? */

 * carriage returns down this path.  So do we still need it?
 */
void
msgbuf_addstr(struct msgbuf *mbp, int pri, const char *str, int filter_cr)
{
	u_int seq;
	size_t len, prefix_len;
	char prefix[MAXPRIBUF];
	char buf[32];
	int i, j, needtime;

	len = strlen(str);
	prefix_len = 0;

	/* If we have a zero-length string, no need to do anything. */
	if (len == 0)
		return;

	mtx_lock_spin(&mbp->msg_lock);

	/*
	 * If this is true, we may need to insert a new priority sequence,
	 * so prepare the prefix.
	 */
	if (pri != -1)
		prefix_len = sprintf(prefix, "<%d>", pri);

	/*
	 * Starting write sequence number.
	 */
	seq = mbp->msg_wseq;

	/*
	 * Whenever there is a change in priority, we have to insert a
	 * newline, and a priority prefix if the priority is not -1.  Here
	 * we detect whether there was a priority change, and whether we
	 * did not end with a newline.  If that is the case, we need to
	 * insert a newline before this string.
	 */
	if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
		msgbuf_do_addchar(mbp, &seq, '\n');
		mbp->msg_flags &= ~MSGBUF_NEEDNL;
	}

	needtime = 1;
	for (i = 0; i < len; i++) {
		/*
		 * If we just had a newline, and the priority is not -1
		 * (and therefore prefix_len != 0), then we need a priority
		 * prefix for this line.
		 */
		if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
			int j;

			for (j = 0; j < prefix_len; j++)
				msgbuf_do_addchar(mbp, &seq, prefix[j]);
		}

		if (msgbuf_show_timestamp && needtime == 1 &&
		    (mbp->msg_flags & MSGBUF_NEEDNL) == 0) {