IEEE Standards Interpretation for IEEE Std 1003.1™-1990 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)
Copyright © 2001 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 #85
Topic: signal.h and namespace Relevant Sections: Subclause 3.3.1, P70 & subclause 18.104.22.168, P80 (sigtimedwait())
POSIX defines the sigtimedwait() function, which takes a const struct timespec * as one of it's arguments. This function is declared in the <signal.h> header. However, the synopsis for sigtimedwait() does not specify inclusion of <time.h> which is where the timespec structure is defined. Likewise, the sigtimedwait() description does not state any requirements for defining struct timespec, nor does it allow for the visibility of symbols in <time.h> when including <signal.h>. To include <signal.h> and not define struct timespec will result in compilers generating a warning about a dubious tag declaration for struct timespec. Though POSIX references <time.h> in the Cross- References and See Also sections respectively, and talks about the timespec structure in the text, there is no indication as to how one should go about making this visible.
Add a paragraph after POSIX.1-1996, P70, L50 (description of <signal.h>): Inclusion of the <signal.h> header may make visible symbols allowed by this part of ISO/IEC 9945 to be in the <time.h> header. (This matches the wording used on POSIX.1-1996, P319 for <mqueue.h>.)
The standard does not speak to this issue, and as such no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor.
There appear to be some omissions in the specification. It is recommend that a future revision address this issue. Forwarded to Interpretations group: 26 Feb 1998 Finalized: 30 March 1998