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 port_alert 3C "1 Oct 2003" "SunOS 5.11" "Standard C Library Functions"
 NAME
port_alert - set a port in alert mode

 SYNOPSIS


#include <port.h>

int port_alert(int port, int flags, int events, void *user);




 DESCRIPTION

The port_alert() function transitions a port into or out of alert mode.
A port in alert mode immediately awakens all threads blocked in
port_get(3C) or port_getn(3C). These threads return with an alert
notification that consists of a single port_event_t structure with the
source PORT_SOURCE_ALERT. Subsequent threads trying to retrieve events
from a port that is in alert mode will return immediately with the alert
notification.


A port is transitioned into alert mode by calling the port_alert()
function with a non-zero events parameter. The specified events
and user parameters will be made available in the portev_events and
the portev_user members of the alert notification, respectively. The
flags argument determines the mode of operation of the alert mode:




If flags is set to PORT_ALERT_SET, port_alert() sets the port
in alert mode independent of the current state of the port. The
portev_events and portev_user members are set or updated
accordingly.






If flags is set to PORT_ALERT_UPDATE and the port is not in alert
mode, port_alert() transitions the port into alert mode. The
portev_events and portev_user members are set accordingly.






If flags is set to PORT_ALERT_UPDATE and the port is already in
alert mode, port_alert() returns with an error value of EBUSY.




PORT_ALERT_SET and PORT_ALERT_UPDATE are mutually exclusive.


A port is transitioned out of alert mode by calling the port_alert()
function with a zero events parameter.


Events can be queued to a port that is in alert mode, but they will not be
retrievable until the port is transitioned out of alert mode.

 RETURN VALUES

Upon succesful completion, 0 is returned. Otherwise, -1 is returned and
errno is set to indicate the error.

 ERRORS

The port_alert() function will fail if:


EBADF


The port identifier is not valid.





EBADFD


The port argument is not an event port file descriptor.





EBUSY


The port is already in alert mode.





EINVAL


Mutually exclusive flags are set.




 ATTRIBUTES

See attributes(5) for descriptions of the following attributes:







ATTRIBUTE TYPEATTRIBUTE VALUE
Architectureall
Interface StabilityEvolving
MT-LevelSafe



 SEE ALSO

port_associate(3C), port_create(3C), port_get(3C),
port_send(3C), attributes(5)