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

NAME

adjmsg - trim bytes from a message

SYNOPSIS

#include <sys/stream.h>


int adjmsg(mblk_t *mp, ssize_t len);

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

mp
Pointer to the message to be trimmed.


len
The number of bytes to be removed.

DESCRIPTION

The adjmsg() function removes bytes from a message. |len| (the absolute
value of len) specifies the number of bytes to be removed. The adjmsg()
function only trims bytes across message blocks of the same type.


The adjmsg() function finds the maximal leading sequence of message
blocks of the same type as that of mp and starts removing bytes either
from the head of that sequence or from the tail of that sequence. If len
is greater than 0, adjmsg() removes bytes from the start of the first
message block in that sequence. If len is less than 0, it removes bytes
from the end of the last message block in that sequence.


The adjmsg() function fails if |len| is greater than the number of bytes
in the maximal leading sequence it finds.


The adjmsg() function may remove any except the first zero-length message
block created during adjusting. It may also remove any zero-length
message blocks that occur within the scope of |len|.

RETURN VALUES

The adjmsg() function returns:

1
Successful completion.


0
An error occurred.

CONTEXT

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

SEE ALSO

STREAMS Programming Guide

January 16, 2006 ADJMSG(9F)