0001171: <sys/select.h> doesn’t allow to include <sys/time.h> namespace anymore

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Severity

Type

Date Submitted

Last Update

0001171

[1003.1(2016/18)/Issue7+TC2] Base Definitions and Headers

Objection

Error

2017-11-22 09:52

2019-11-08 10:32

Reporter

martinr

View Status

public

Assigned To

Priority

normal

Resolution

Accepted As Marked

Status

Applied

Name

Martin Rehak

Organization

Oracle Corporation

User Reference

Section

Page Number

399

Line Number

13572

Interp Status

---

Final Accepted Text

See Note: 0004242

Summary

0001171: <sys/select.h> doesn’t allow to include <sys/time.h> namespace anymore

Description

The standard in XPG7 version says for <sys/select.h>:

"Inclusion of the <sys/select.h> header may make visible all symbols from the headers <signal.h> and <time.h>."

In previous version (XPG6) there was also <sys/time.h> allowed to be included in <sys/select.h>, but we were not able to find out why the change happened. We are just guessing that intention was to do reverse inclusion:

The select() was defined in <sys/time.h> in earlier versions of the standard (pre-XPG6). However, with the introduction of pselect() in <sys/select.h> in XPG6, the move was made to define ALL the related definitions for pselect() and select() in <sys/select.h>. As noted on the pselect() page in SUSv4 Rationale section, "Backwards-compatibility to existing XSI implementations is handled by allowing <sys/time.h> to include <sys/select.h>. This is KEY statement.

Looking at the <sys/select.h> header, it appears the intent was that <sys/select.h> would now define the timeval structure and it's members. In XPG7, the specification for both <sys/time.h> and <sys/select.h> states that the respective header:

"...shall define the timeval structure, which shall include at least the following members:

time_t tv_sec Seconds.
suseconds_t tv_usec Microseconds."

This appears to be a bug. Given that <sys/time.h> further states that "Inclusion of the <sys/time.h> header may make visible all the symbols from the <sys/select.h> header", along with the previously quoted Rationale, it appears the intent was indeed to move the timeval structure definition to <sys/select.h>. Hence, the description in <sys/time.h> should probably read:

"The <sys/time.h> header shall define the timeval structure as described in <sys/select.h>.

Desired Action

1) Clarify why the mentioned change happened.

2) If our guessing is right change the <sys/time.h> description (Page 399 / Line: 13572) to:

The <sys/time.h> header shall define the timeval structure as described in <sys/select.h>.

Tags

tc3-2008

Attached Files

Relationships

Notes

(0004242)
nick (manager)
2019-02-07 16:23

Change page 399 lines 13572-13575 (<sys/time.h>) from:

The <sys/time.h> header shall define the timeval structure, which shall include at least the following members:
time_t tv_sec Seconds.
suseconds_t tv_usec Microseconds.

to:

The <sys/time.h> header shall define the fd_set type and
the timeval structure as described in <sys/select.h>.

Delete page 399 line 13582:

The <sys/time.h> header shall define the fd_set type as described in <sys/select.h>.

Change the RATIONALE section on page 400 line 13609 from:

None.

to:

The <sys/time.h> header refers to <sys/select.h> for the definition of the timeval structure, instead of the other way round, because <sys/time.h> is an optional (XSI) header whereas <sys/select.h> is mandatory.

Issue History
Date Modified	Username	Field	Change
2017-11-22 09:52	martinr	New Issue
2017-11-22 09:52	martinr	Name	=> Martin Rehak
2017-11-22 09:52	martinr	Organization	=> Oracle Corporation
2017-11-22 09:52	martinr	Section	=> <sys/time.h>
2017-11-22 09:52	martinr	Page Number	=> 399
2017-11-22 09:52	martinr	Line Number	=> 13572
2019-02-07 16:23	nick	Note Added: 0004242
2019-02-07 16:24	nick	Interp Status	=> ---
2019-02-07 16:24	nick	Final Accepted Text	=> See Note: 0004242
2019-02-07 16:24	nick	Status	New => Resolved
2019-02-07 16:24	nick	Resolution	Open => Accepted As Marked
2019-02-07 16:24	nick	Tag Attached: tc3-2008
2019-11-08 10:32	geoffclare	Status	Resolved => Applied

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