IEEE Standards Interpretations for IEEE Std 1003.1b™-1993 IEEE Standard for Information Technology - Portable Operating System Interfaces (POSIX(R)) - Part 1: System Application Program Interface (API) - Amendment 1: Realtime Extension [C language]
Copyright © 1996 by the Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue New York, New York 10016-5997 USA All Rights Reserved.
Interpretations are issued to explain and clarify the intent of a standard and do not constitute an alteration to the original standard. In addition, interpretations are not intended to supply consulting information. Permission is hereby granted to download and print one copy of this document. Individuals seeking permission to reproduce and/or distribute this document in its entirety or portions of this document must contact the IEEE Standards Department for the appropriate license. Use of the information contained in this document is at your own risk.
IEEE Standards Department Copyrights and Permissions 445 Hoes Lane, Piscataway, New Jersey 08855-1331, USA
Interpretation Request #2
Topic: action on synchronous signal acceptance Relevant Sections: 220.127.116.11 Classification: Ambiguous
The circumstance under which these actions are to be taken is termed delivery in 18.104.22.168. Also, in 22.214.171.124, the statement is made that signals can be blocked from delivery, and remain pending until either unblocked or the action is set to ignore. No mention is made of synchronous acceptance, as specified by sigwaitinfo() and sigtimedwait() (3.3.8). When a signal is synchronously accepted. 1) Is an implementation required to take the associated action when a signal is accepted synchronously? 2) Is an implementation permitted to take the associated action when a signal is accepted synchronously? 3) Is an implementation forbidden to take the associated action when a signal is accepted synchronously?
The standard is not clear in this area. It is ambiguous as to whether the synchronous selection of a signal by sigwaitinfo constitutes delivery or not. The interpretation is that an implementation is permitted to take the associated action when a signal is accepted synchronously: neither required nor forbidden. The lack of clarity is being referred to the sponsor for consideration. The interpretations committee suggests that an application would prefer to only receive each signal once and that implementations might wish to implement the facility in this manner (which is allowed but not required). The answers to the requestor's 3 questions are thus: no, yes, no.
Rationale for Interpretation