PORT_CREATE(3C) Standard C Library Functions PORT_CREATE(3C)


port_create - create a port


#include <port.h>

int port_create(void);


The port_create() function establishes a queue that multiplexes events
from disjoint sources. Each source has a corresponding object type and
source-specific mechanism for associating an object with a port.

source object type association mechanism
PORT_SOURCE_AIO struct aiocb aio_read(3C),
PORT_SOURCE_FD file descriptor port_associate(3C)
PORT_SOURCE_MQ mqd_t mq_notify(3C)
PORT_SOURCE_TIMER timer_t timer_create(3C)
PORT_SOURCE_USER uintptr_t port_send(3C)
PORT_SOURCE_ALERT uintptr_t port_alert(3C)
PORT_SOURCE_FILE file_obj_t port_associate(3C)

PORT_SOURCE_AIO events represent the completion of an asynchronous I/O
transaction. An asynchronous I/O transaction is associated with a port by
specifying SIGEV_PORT as its notification mechanism. See aio_read(3C),
aio_write(3C), lio_listio(3C), and aio.h(3HEAD) for details.

PORT_SOURCE_FD events represent a transition in the poll(2) status of a
given file descriptor. Once an event is delivered, the file descriptor is
no longer associated with the port. A file descriptor is associated (or
re-associated) with a port using the port_associate(3C) function.

PORT_SOURCE_MQ events represent a message queue transition from empty to
non-empty. A message queue is associated with a port by specifying
SIGEV_PORT as its notification mechanism. See mq_notify(3C) for more

PORT_SOURCE_TIMER events represent one or more timer expirations for a
given timer. A timer is associated with a port by specifying SIGEV_PORT
as its notification mechanism. See timer_create(3C) for more information.

PORT_SOURCE_USER events represent user-defined events. These events are
generated by port_send(3C) or port_sendn(3C).

PORT_SOURCE_ALERT events indicate that the port itself is in alert mode.
The mode of the port is changed with port_alert(3C).The port_create()
function returns a file descriptor that represents a newly created port.
The close(2) function destroys the port and frees all allocated

PORT_SOURCE_FILE events represent file/directory status change. Once an
event is delivered, the file object associated with the port is no longer
active. It has to be reassociated to activate. A file object is
associated or reassociated with a port using the port_associate(3C).

The port_get(3C) and port_getn(3C) functions retrieve events from a port.
They ignore non retrievable events (non-own or non-shareable events).

As a port is represented by a file descriptor, ports are shared between
child and parent processes after fork(). Both can continue to associate
sources with the port, both can receive events from the port, and events
associated with and/or generated by either process are retrievable in the
other. Since some events might not have meaning in both parent and child,
care must be taken when using ports after fork().

If a port is exported to other processes, the port is destroyed on last

PORT_SOURCE_USER and PORT_SOURCE_ALERT events can be distributed across
processes. PORT_SOURCE_FD events can only be shared between processes
when child processes inherit opened file decriptors from the parent
process. See fork(2). PORT_SOURCE_TIMER and PORT_SOURCE_AIO cannot be
shared between processes.


Upon successful completion, the port_create() function returns a non-
negative value, the port identifier. Otherwise, -1 is returned and errno
is set to indicate the error.


The port_create() function will fail if:

The maximum allowable number of ports is currently open in the
system. The maximum allowable number of ports is the minimum
value of the project.max-port-ids resource control. See
setrctl(2) and rctladm(8) for information on using resource

The process has too many open descriptors.


See attributes(7) for descriptions of the following attributes:

|Architecture | all |
|Interface Stability | Committed |
|MT-Level | Safe |


close(2), exit(2), fork(2), poll(2), setrctl(2), aio_read(3C),
aio_write(3C), lio_listio(3C), mq_notify(3C), port_associate(3C),
port_get(3C), timer_create(3C), aio.h(3HEAD), attributes(7), rctladm(8)

April 9, 2016 PORT_CREATE(3C)