NAME

canputnext, bcanputnext - test for room in next module's message queue

SYNOPSIS

#include <sys/stream.h>

int canputnext(queue_t * q);
int bcanputnext(queue_t * q, unsigned char pri);

ARGUMENTS

q

Pointer to a message queue belonging to the invoking module.

pri

Minimum priority level.

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

DESCRIPTION

The invocation canputnext(q); is an atomic equivalent of the canput(q.q_next); routine. That is, the STREAMS framework provides whatever mutual exclusion is necessary to insure that dereferencing q through its q_next field and then invoking canput(9F) proceeds without interference from other threads.

bcanputnext(q, pri); is the equivalent of the bcanput(q.q_next, pri); routine.

canputnext(q); and bcanputnext(q, pri); should always be used in preference to canput(q.q_next); and bcanput(q.q_next, pri); respectively.

See canput(9F) and bcanput(9F) for further details.

RETURN VALUES

1

If the message queue is not full.

0

If the queue is full.

CONTEXT

canputnext( ) and bcanputnext( ) can be called from user or interrupt context.

WARNINGS

Drivers are responsible for both testing a queue with canputnext( ) or bcanputnext( ) and refraining from placing a message on the queue if the queue is full.

SEE ALSO

bcanput(9F), canput(9F)

Writing Device Drivers

STREAMS Programmer's Guide