msgb(9S)

NAME

msgb − STREAMS message block structure

SYNOPSIS

#include <sys/stream.h>

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

DESCRIPTION

A STREAMS message is made up of one or more message blocks, referenced by a pointer to a msgb structure. The b_next and b_prev pointers are used to link messages together on a QUEUE. The b_cont pointer links message blocks together when a message is composed of more than one block.

Each msgb structure also includes a pointer to a datab(9S) structure, the data block (which contains pointers to the actual data of the message), and the type of the message.

STRUCTURE MEMBERS

struct msgb	∗b_next;	/∗ next message on queue ∗/
struct msgb	∗b_prev;	/∗ previous message on queue ∗/
struct msgb	∗b_cont;	/∗ next message block ∗/
unsigned char	∗b_rptr;	/∗ 1st unread data byte of buffer ∗/
unsigned char	∗b_wptr;	/∗ 1st unwritten data byte of buffer ∗/
struct datab	∗b_datap;	/∗ pointer to data block ∗/
unsigned char	b_band;	/∗ message priority ∗/
unsigned short	b_flag;	/∗ used by stream head ∗/

Valid flags are as follows:

MSGMARK last byte of message is "marked".

MSGDELIM message is delimited.

The msgb structure is defined as type mblk_t.

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