backq(9F) Kernel Functions for Drivers backq(9F)
NAME
backq - get pointer to the queue behind the current queue
SYNOPSIS
#include <sys/stream.h>
queue_t *backq(queue_t *cq);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
cq The pointer to the current queue. queue_t is an alias for the queue(9S) structure.
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.
SEE ALSO
queue(9S)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.10 11 Apr 1991 backq(9F)
