PORT_ALERT(3C) Standard C Library Functions PORT_ALERT(3C)
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:
o 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.
o 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.
o 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 successful 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(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Architecture | all |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+
SEE ALSO
port_associate(3C),
port_create(3C),
port_get(3C),
port_send(3C),
attributes(7) April 9, 2016 PORT_ALERT(3C)
