man pages section 3: Basic Library Functions

port_dissociate(3C)

Name

port_associate, port_dissociate– associate or dissociate the object with the port

Synopsis

#include <port.h>

int port_associate(int port, int source, uintptr_t object,
     int events, void *user);

int port_dissociate(int port, int source, uintptr_t object);

Description

The port_associate() function associates specific events of a given object with a port. Only objects associated with a particular port are able to generate events that can be retrieved using port_get(3C) or port_getn(3C). The delivery event has its portev_user member set to the value specified in the user parameter. If the specified object is already associated with the specified port, the port_associate() function serves to update the events and user arguments of the association. The port_dissociate() function removes the association of an object with a port.

The only objects associated with a port by way of the port_associate() function are objects of type PORT_SOURCE_FD. Objects of other types have type-specific association mechanisms. A port_notify_t structure, defined in <port.h>, is used to specify the event port and an application-defined cookie to associate with these event sources. See port_create(3C) and signal.h(3HEAD).

The port_notify_t structure contains the following members:

int       portntfy_port;  /* bind request(s) to port */
void      *portntfy_user; /* user defined cookie */

Objects of type PORT_SOURCE_FD are file descriptors. The event types for PORT_SOURCE_FD objects are described in poll(2). At most one event notification will be generated per associated file descriptor. For example, if a file descriptor is associated with a port for the POLLRDNORM event and data is available on the file descriptor at the time the port_associate() function is called, an event is immediately sent to the port. If data is not yet available, one event is sent to the port when data first becomes available.

When an event for a PORT_SOURCE_FD object is retrieved, the object no longer has an association with the port. The event can be processed without the possibility that another thread can retrieve a subsequent event for the same object. After processing of the file descriptor is completed, the port_associate() function can be called to reassociate the object with the port.

The parent and child processes are allowed to retrieve events from file descriptors shared after a call to fork(2). The process performing the first association with a port (parent or child process) is designated as the owner of the association. Only the owner of an association is allowed to dissociate the file descriptor from a port. The association is removed if the owner of the association closes the port .

Return Values

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

Errors

The port_associate() and port_dissociate() functions will fail if:

EBADF: The port identifier is not valid.
EBADFD: The source argument is of type PORT_SOURCE_FD and the object argument is not a valid file descriptor.
EINVAL: The source argument is not valid.

The port_associate() function will fail if:

EAGAIN

The maximum number of objects associated with the port was exceeded. The maximum allowable number of events or association of objects per port is the minimum value of the process.max-port-events resource control at the time port_create(3C) was used to create the port. See setrctl(2) and rctladm(1M) for information on using resource controls.

The number of objects associated with a port is composed of all supported resource types. Some of the source types do not explicitly use the port_associate() function.

ENOMEM

The physical memory limits of the system have been exceeded.

The port_dissociate() function will fail if:

EACCES: The process is not the owner of the association.
ENOENT: The specified object is not associated with the port.

Examples

Example 1 Retrieve data from a pipe file descriptor.

The following example retrieves data from a pipe file descriptor.

#include <port.h>

int               port;
int               fd;
int               error;
int               index;
void              *mypointer;
port_event_t      pev;
struct timespec_t timeout;
char              rbuf[STRSIZE];
int               fds[MAXINDEX];

/* create a port */
port = port_create();

for (index = 0; index < MAXINDEX; index++) {
        error = mkfifo(name[index], S_IRWXU | S_IRWXG | S_IRWXO);
        if (error)
                /* handle error code */
        fds[index] = open(name[index], O_RDWR);

        /* associate pipe file descriptor with the port */
        error = port_associate(port, PORT_SOURCE_FD, fds[index],
            POLLIN, mypointer);
}
...
timeout.tv_sec = 1;     /* user defined */
timeout.tv_nsec = 0;

/* loop to retrieve data from the list of pipe file descriptors */
for (...) {
        /* retrieve a single event */
        error = port_get(port, &pev, &timeout);
        if (error) {
                /* handle error code */
        }
        fd = pev.portev_object;
        if (read(fd, rbuf, STRSIZE)) {
                /* handle error code */
        }
        if (fd-still-accepting-data) {
                /*
                 * re-associate the file descriptor with the port.
                 * The re-association is required for the
                 * re-activation of the data detection.
                 * Internals events and user arguments are set to the
                 * new (or the same) values delivered here.
                 */
                error = port_associate(port, PORT_SOURCE_FD, fd, POLLIN,
                    pev.portev_user);
        } else {
                /*
                 * If file descriptor is no longer required,
                 * - it can remain disabled but still associated with
                 *   the port, or
                 * - it can be dissociated from the port.
                 */
        }

Example 2 Bind AIO transaction to a specific port.

The following example binds the AIO transaction to a specific port.

#include <port.h>

int             port;
port_notify_t   pn;
aiocb_t         aiocb;
aiocb_t         *aiocbp;
void            *mypointer;
int             error;
int             my_errno;
int             my_status;
struct timespec_t timeout;
port_event_t    pev;

port = port_create();
...
/* fill AIO specific part */
aiocb.aio_fildes = fd;
aiocb.aio_nbytes = BUFSIZE;
aiocb.aio_buf = bufp;
aiocb.aio_offset = 0;
aiocb.aio_sigevent.sigev_notify = SIGEV_NONE; /* SIGV_SIGNAL, ... */
aiocb.aio_sigevent.sigev_signo = <signal-no>; /* if SIGV_SIGNAL */

/* port specific part */
pn.portnfy_port = port;
pn.portnfy_user = mypointer;

aiocb.aio_sigevent.sigev_notify = SIGEV_PORT;
aiocb.aio_sigevent.sigev_value.sival_ptr = &pn

/*
 * The aio_read() function binds internally the asynchronous I/O
 * transaction with the port delivered in port_notify_t.
 */
error = aio_read(&aiocb);

timeout.tv_sec = 1;     /* user defined */
timeout.tv_nsec = 0;

/* retrieve a single event */
error = port_get(port, &pev, &timeout);
if (error) {
        /* handle error code */
}

/*
 * pev.portev_object contains a pointer to the aiocb structure
 * delivered in port_notify_t (see aio_read()).
 */
aiocbp = pev.portev_object;

/* check error code and return value in
my_errno = aio_error(aiocbp);
...
my_status = aio_return(aiocbp);
...

Attributes

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

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Architecture	all
Availability	SUNWcsr, SUNWhea
Interface Stability	Evolving
MT-Level	Safe