'\" te
.\" Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 1989 AT&T
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.TH DATAB 9S "Oct 24, 2003"
.SH NAME
datab, dblk \- STREAMS message data structure
.SH SYNOPSIS
.LP
.nf
#include <sys/stream.h>
.fi

.SH INTERFACE LEVEL
.sp
.LP
Architecture independent level 1 (DDI/DKI).
.SH DESCRIPTION
.sp
.LP
The \fBdatab\fR structure describes the data of a STREAMS message. The actual
data contained in a STREAMS message is stored in a data buffer pointed to by
this structure. A  \fBmsgb\fR (message block) structure includes a field that
points to a \fBdatab\fR structure.
.sp
.LP
Because a data block can have more than one message block pointing to it at one
time, the \fBdb_ref\fR member keeps track of a data block's references,
preventing it from being deallocated until all message blocks are finished with
it.
.SH STRUCTURE MEMBERS
.sp
.in +2
.nf
unsigned char     *db_base;     /* first byte of buffer */
unsigned char     *db_lim;      /* last byte (+1) of buffer */
unsigned char      db_ref;      /* # of message pointers to this data */
unsigned char      db_type;     /* message type */
.fi
.in -2

.sp
.LP
A \fBdatab\fR structure is defined as type \fBdblk_t\fR.
.SH SEE ALSO
.sp
.LP
\fBfree_rtn\fR(9S), \fBmsgb\fR(9S)
.sp
.LP
\fIWriting Device Drivers\fR
.sp
.LP
\fISTREAMS Programming Guide\fR