|SENDSYSLOG(2)||System Calls Manual||SENDSYSLOG(2)|
char *msg, size_t
sendsyslog() function is used to transmit a syslog(3) formatted message direct to syslogd(8) without requiring the allocation of a socket. The msg is not NUL terminated and its len is limited to 8192 bytes. If
LOG_CONSis specified in the flags argument, and syslogd(8) is not accepting messages, the message will be sent to the console. This is used internally by syslog_r(3), so that messages can be sent during difficult situations. If sending to syslogd(8) fails, dropped messages are counted. When syslogd(8) works again, a warning with the counter and error number is logged.
To receive messages from the kernel,
syslogd(8) has to create a datagram
socket pair and register one end. This registration is done by opening the
/dev/klog device and passing one file descriptor of
the socket pair as argument to ioctl(2)
LIOCSFD invoked on the klog file descriptor. After
that the messages can be be read from the other end of the socket pair. By
utilizing /dev/klog the access to log messages is
limited to processes that may open this device.
sendsyslog() can fail if:
sendsyslog() function call appeared in OpenBSD 5.6. The flags argument was added in OpenBSD 6.0.
|September 27, 2017||OpenBSD-current|