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Communications Technical Reference, Volume 2

I_ATMARK streamio Operation

Purpose

Checks to see if a message is marked.

Description

The I_ATMARK operation shows the user if the current message on the stream-head read queue is marked by a downstream module. The arg parameter determines how the checking is done when there are multiple marked messages on the stream-head read queue. The possible values for the arg parameter are:

ANYMARK Read to determine if the message is marked by a downstream module.
LASTMARK Read to determine if the message is the last one marked on the queue by a downstream module.

The I_ATMARK operation returns a value of 1 if the mark condition is satisfied. Otherwise, it returns a value of 0.

Error Codes

If unsuccessful, the errno global variable is set to the following value:

EINVAL The value of the arg parameter could not be used.

Implementation Specifics

This operation is part of STREAMS Kernel Extensions.

Related Information

The streamio operations.

Understanding STREAMS Messages in AIX Version 4.3 Communications Programming Concepts.


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