backq(9F)

NAME

backq − get pointer to the queue behind the current queue

SYNOPSIS

#include <sys/stream.h>

queue_t ∗backq(queue_t ∗cq);

ARGUMENTS

cq The pointer to the current queue. queue_t is an alias for the queue(9S) structure.

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

DESCRIPTION

backq() returns a pointer to the queue preceding cq (the current queue). If cq is a read queue, backq() returns a pointer to the queue downstream from cq, unless it is the stream end. If cq is a write queue, backq() returns a pointer to the next queue upstream from cq, unless it is the stream head.

RETURN VALUES

If successful, backq() returns a pointer to the queue preceding the current queue. Otherwise, it returns NULL.

CONTEXT

backq() can be called from user or interrupt context.

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