'\" tr.\" -*- nroff -*-.\".\" @(#) backq.9,v 1.1.4.1 2004/01/12 23:32:58 brian Exp.\".\" =========================================================================.\".\" Copyright (C) 2001-2004  OpenSS7 Corp. <www.openss7.com>.\".\" All Rights Reserved..\".\" Permission is granted to make and distribute verbatim copies of this.\" manual provided the copyright notice and this permission notice are.\" preserved on all copies..\".\" Permission is granted to copy and distribute modified versions of this.\" manual under the conditions for verbatim copying, provided that the.\" entire resulting derived work is distributed under the terms of a.\" permission notice identical to this one.\" .\" Since the Linux kernel and libraries are constantly changing, this.\" manual page may be incorrect or out-of-date.  The author(s) assume no.\" responsibility for errors or omissions, or for damages resulting from.\" the use of the information contained herein.  The author(s) may not.\" have taken the same level of care in the production of this manual,.\" which is licensed free of charge, as they might when working.\" professionally..\" .\" Formatted or processed versions of this manual, if unaccompanied by.\" the source, must acknowledge the copyright and authors of this work..\".\" =========================================================================.\".\" Modified 2004/01/12 23:32:58 by brian.\".\" =========================================================================.so lis.macros.R1bracket-label "\fR[\fB" "\fR]" "\fR, \fB"no-default-databasedatabase lis.refsaccumulatemove-punctuationabbreviate Ajoin-authors ", " ", " " and "et-al " et al" 2 3abbreviate-label-ranges ".."sort-adjacent-labels.R2.\".\".TH BACKQ 9 "2004/01/12 23:32:58" "LiS-2_16_18-8" "Linux STREAMS DDI/DKI".SH NAME.B backq\- find the upstream or downstream \fISTREAMS\fR queue.SH SYNOPSIS.PP.B #include <sys/stream.h>.HP 8.BI "queue_t *" bq " = backq(queue_t *" q );.SH DESCRIPTION.PP.BR backq ()returns the queue,.IR bq ,which feeds messages to the specified queue,.IR q ..PPIf the specified queue,.IR q ,is a normal read queue, then the returned back queue,.IR bq ,is the downstream queue.If the specified queue,.IR q ,is a normal write queue, then the returned back queue,.IR bq ,is the upstream queue..PPIf the specified queue,.IR q ,is a FIFO read queue, then the returned back queue,.IR bq ,is the FIFO write queue.If the specified queue,.IR q ,is a FIFO write queue, then the returned back queue,.IR bq ,is the FIFO read queue..PPIf the specified queue,.IR q ,is a pipe read queue, then the returned back queue,.IR bq ,is write queue at the other end of the pipe.If the specified queue,.IR q ,is a pipe write queue, then the returned back queue,.IR bq ,is the read queue at the other end of the pipe..SH "RETURN VALUES".PPUpon success,.BR backq ()returns the pointer to the resulting queue..PPUpon failure,.BR backq ()returns.BR NULL ..SH ERRORS.PP.BR backq ()returns.B NULLwhen the specified queue,.IR q ,is.BR NULL ,the pointer.I qis not a pointer to a queue structure,or there is no upstream queue for a write queue or downstream queue for a readqueue..SH CAVEATS.PP.B LiS.[LiS.]will also return.B NULLif there is an internal error: that is, if the OTHER(q) pointer is.BR NULL ..SH "SEE ALSO".PP.BR strqget "(9) and ".BR strqset (9)..SH HISTORY.PP.BR backq ()first appeared in SVR 3 STREAMS.[svr3.]and continued in SVR 4.2 STREAMS..[svr42.].SH VERSIONS.PPThis manpage was written for.B LiS\c.[LiS.].\".\".[$LIST$.].TA