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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 charb_band;/* message priority */
unsigned shortb_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.

See Also

datab(9S)

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