Minutes of the 29th May 2014 Teleconference

[Andrew Josey]

All
Enclosed are the minutes of the latest meeting
regards
Andrew
-----

Minutes of the 29th May 2014 Teleconference Austin-657 Page 1 of 1
Submitted by Andrew Josey, The Open Group. 30th May 2014

Attendees:

Nick Stoughton, USENIX, ISO/IEC JTC 1/SC 22 OR
Mark Ziegast, SHware Systems
Geoff Clare, The Open Group
Don Cragun, IEEE PASC OR
Andrew Josey, The Open Group
David Clissold, IBM
Richard Hansen, BBN
Eric Blake, Red Hat
Martin Rehak, Oracle
Mark Brown, Canonical

Apologies
Joerg Schilling


* General news

A query was raised about table labelling in the specification.
Andrew took an action to check with our editor and report back to the group.


* Outstanding actions

+Bug 0000251: Forbid newline, or even bytes 1 through 31 (inclusive), in filenames OPEN
http://austingroupbugs.net/view.php?id=251
Don has an action to produce a proposal.

+Bug 0000561: NUL-termination of sun_path in Unix sockets OPEN
http://austingroupbugs.net/view.php?id=561
Eric has an action to update the proposal.

+Bug 0000573: Please add '+' to the portable filename character set OPEN
http://austingroupbugs.net/view.php?id=573
Joerg has an action to prepare a proposed change.

+Bug 0000592: consistent use of struct timespec OPEN
http://austingroupbugs.net/view.php?id=592
Jim had provided additional information in bugnote 1627.
This was discussed and Jim took an action to provide further information.

+Bug 0000598: OH shading and new interfaces OPEN
http://austingroupbugs.net/view.php?id=598
Eric has an action to propose a new solution with self-contained headers.

+Bug 0000517: EBNF support OPEN
http://austingroupbugs.net/view.php?id=517
Action on Joerg to look at this.

+Bug 0000633: SIGEV_THREAD delivery renders many signal interfaces unsafe
OPEN
http://austingroupbugs.net/view.php?id=633
We noted that feedback has settled down on the mailing list, and
will discuss next session.

+Bug 0000657: Conditions under which fmemopen() write a NUL to the buffer
are insufficiently specified OPEN
http://austingroupbugs.net/view.php?id=657
Eric has an action to propose wording to clarify the behavior for
fmemopen(), and also to contact the glibc developers to get their
feedback.

+Bug 0000658: Undefined/unspecified behavior clauses in description of
open have race conditions OPEN
http://austingroupbugs.net/view.php?id=658
It was noted that there is some overlap with changes in TC1. Eric took an
action to update the proposal to resolve the overlaps appropriately.

+Bug 0000615: pthread_setcancelstate should be async-signal-safe OPEN
http://austingroupbugs.net/view.php?id=615
We now have reports on AIX and Apple. Jim to report back on whether
pthread_cancelstate() is async-signal-safe on Solaris. Andrew to ask
HP whether pthread_cancelstate() is async-signal-safe on HP-UX.

+Bug 622 left open pending resolution of 615.
http://austingroupbugs.net/view.php?id=622

+Bug 0000672: Necessary step(s) to synchronize filename operations on disk
OPEN
http://austingroupbugs.net/view.php?id=672

Geoff has a new proposed resolution in note 1618. Decided to solicit input
from FS developers. Eric to go to Linux, David to AIX and Jim to Solaris.
Jim has completed his action (see bugnote 1691).
Andrew should chase HP and Apple for input.

+Bug 0000663: Specification of str[n]casecmp is ambiguous reopened
http://austingroupbugs.net/view.php?id=663

Action on David to follow up with the IBM developers about the EBCDIC
collation sequence.

Bug 696 either NAME_MAX shouldn't be optional, or readdir_r() needs clarification
http://www.austingroupbugs.net/view.php?id=696

Don has an action to propose a resolution.

Bug 0000721: Internal storage vs static storage OPEN
http://austingroupbugs.net/view.php?id=721

This item is still open.

Bug 0000375: Extend test/[...] conditionals: ==, <, >, -nt, -ot, -ef OPEN
http://austingroupbugs.net/view.php?id=375

This is still left open due to discussions pending on the reflector.

Bug 0000789: Add set -o pipefail OPEN
http://austingroupbugs.net/view.php?id=789



* Current Business

Bug #811: precondition for mutex destruction unclear; example contradicts normative text OPEN
http://www.austingroupbugs.net/view.php?id=811

We have left this item open pending further input from Dave Butenhof on
supplying a new example.


Bug #615: pthread_setcancelstate should be async-signal-safe Accepted as Marked
http://austingroupbugs.net/view.php?id=615

This item is tagged for TC2-2008.

An interpretation is required.

Interpretation response:
The standard states that when a thread's cancelability state is
PTHREAD_CANCEL_DEFERRED, cancellation requests are held pending
until a cancellation point is reached, and conforming implementations
must conform to this. However, concerns have been raised about this
which are being referred to the sponsor (some cancellation points
may be reached in an asynchronous signal handler because some
cancellation points are in async-signal-safe functions).

Rationale:
In order to write a signal handler for an asynchronous signal which
can run safely in a cancellable thread, pthread_setcancelstate()
must be used to disable cancellation for the duration of any calls
that the signal handler makes which are cancellation points. However,
the standard does not currently permit strictly conforming applications
to do this since pthread_setcancelstate() is not required to be
async-signal-safe.

Notes to the Editor (not part of this interpretation):

At page 489 line 16756 (XSH 2.4.3 Signal Actions), change:

All functions not in the above table are considered to be unsafe with respect to signals.

to:

Any function not in the above table may be unsafe with respect
to signals. Implementations may make other interfaces
async-signal-safe.

At page 1695 line 54349 (XSH pthread_setcancelstate() future directions), change:

None.
to:
The pthread_setcancelstate() function may be added to the table
of async-signal-safe functions in section 2.4.3 on page 489.


Bug 0000841: pthread_setcancelstate should be async-signal-safe Accepted
http://austingroupbugs.net/view.php?id=841

The item is tagged for Issue 8. See the Desired Action

At page 489 lines 16722-16755 (XSH 2.4.3) insert:
pthread_setcancelstate()


After applying the changes from 0000615, at page 489 line 16756 (XSH 2.4.3 Signal Actions), change:
Implementations may make other interfaces async-signal-safe.
to:
It is implementation-defined which additional interfaces, if
any, are also async-signal-safe.

At page 515 line 17840 section 2.9.5.4 Async-Cancel Safety add two paragraphs:

If a thread has asynchronous cancellation enabled and is cancelled
during execution of a function that is not async-cancel-safe,
the behavior is undefined.

If a thread has deferred cancellation enabled, a signal catching
function is called in that thread during execution of a function
that is not async-cancel-safe, and the signal catching function
calls any function that is a cancellation point while a
cancellation is pending for the thread, without first disabling
cancellation, the behavior is undefined.


At page 1694 after line 54312 (XSH pthread_setcancelstate() description) insert a new paragraph:
The pthread_setcancelstate() function shall be async-signal-safe.

After applying the changes in 0000615, at page 1695 line 54349 (XSH pthread_setcancelstate() future directions), change:
The pthread_setcancelstate() function may be added to the table
of async-signal-safe functions in section 2.4.3 on page 489.
to:
None.

Bug #622: Disallow loophole for asynchronous cancellation of any function OPEN
http://austingroupbugs.net/view.php?id=622

We plan to visit this item next week.

Next Steps
----------

The next call is on June 5, 2014 (a Thursday)

Calls are anchored on US time. (8am Pacific)

This call will be for the regular 90 minutes.

http://austingroupbugs.net

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password=2115756#

--------
Andrew Josey The Open Group
Austin Group Chair Apex Plaza, Forbury Road
Email: a.josey-7882/***@public.gmane.org Reading,Berks.RG1 1AX,England
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