Function xo_send_syslog

tools/libxo/libxo/xo_syslog.c:167–278

* Handle the work of transmitting the syslog message */

 * Handle the work of transmitting the syslog message
 */
static void
xo_send_syslog (char *full_msg, char *v0_hdr,
		char *text_only)
{
    if (xo_syslog_send) {
	xo_syslog_send(full_msg, v0_hdr, text_only);
	return;
    }

    int fd;
    int full_len = strlen(full_msg);

    /* Output to stderr if requested, then we've been passed a v0 header */
    if (v0_hdr) {
        struct iovec iov[3];
        struct iovec *v = iov;
        char newline[] = "\n";

        v->iov_base = v0_hdr;
        v->iov_len = strlen(v0_hdr);
        v += 1;
        v->iov_base = text_only;
        v->iov_len = strlen(text_only);
        v += 1;
        v->iov_base = newline;
        v->iov_len = 1;
        v += 1;
        REAL_VOID(writev(STDERR_FILENO, iov, 3));
    }

    /* Get connected, output the message to the local logger. */
    if (!xo_opened)
        xo_open_log_unlocked(xo_logtag, xo_logstat | LOG_NDELAY, 0);
    xo_connect_log();

    /*
     * If the send() fails, there are two likely scenarios: 
     *  1) syslogd was restarted
     *  2) /var/run/log is out of socket buffer space, which
     *     in most cases means local DoS.
     * If the error does not indicate a full buffer, we address
     * case #1 by attempting to reconnect to /var/run/log[priv]
     * and resending the message once.
     *
     * If we are working with a privileged socket, the retry
     * attempts end there, because we don't want to freeze a
     * critical application like su(1) or sshd(8).
     *
     * Otherwise, we address case #2 by repeatedly retrying the
     * send() to give syslogd a chance to empty its socket buffer.
     */

    if (send(xo_logfile, full_msg, full_len, 0) < 0) {
        if (errno != ENOBUFS) {
            /*
             * Scenario 1: syslogd was restarted
             * reconnect and resend once
             */