illumos: manual page: rmvb.9f

RMVB(9F) Kernel Functions for Drivers RMVB(9F)

NAME

rmvb - remove a message block from a message

SYNOPSIS

#include <sys/stream.h>

mblk_t *rmvb(mblk_t *mp, mblk_t *bp);

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

mp
Message from which a block is to be removed. mblk_t is an instance
of the msgb(9S) structure.

bp
Message block to be removed.

DESCRIPTION

The rmvb() function removes a message block (bp) from a message (mp), and
returns a pointer to the altered message. The message block is not freed,
merely removed from the message. It is the module or driver's
responsibility to free the message block.

RETURN VALUES

If successful, a pointer to the message (minus the removed block) is
returned. The pointer is NULL if bp was the only block of the message
before rmvb() was called. If the designated message block (bp) does not
exist, -1 is returned.

CONTEXT

The rmvb() function can be called from user, interrupt, or kernel
context.

EXAMPLES

This routine removes all zero-length M_DATA message blocks from the given
message. For each message block in the message, save the next message
block (line 10). If the current message block is of type M_DATA and has
no data in its buffer (line 11), then remove it from the message (line
12) and free it (line 13). In either case, continue with the next message
block in the message (line 16).

1 void
2 xxclean(mp)
3 mblk_t *mp;
4 {
5 mblk_t *tmp;
6 mblk_t *nmp;
7
8 tmp = mp;
9 while (tmp) {
10 nmp = tmp->b_cont;
11 if ((tmp->b_datap->db_type == M_DATA) &&
(tmp->b_rptr == tmp->b_wptr)) {
12 (void) rmvb(mp, tmp);
13 freeb(tmp);
14 }
15 tmp = nmp;
16 }
17 }