This Week on perl5-porters - 25-31 May 2008
"I've fixed the bug itself as change #33952. (Whoo hoo! A bug that
was easy to locate, fix, and test for. You don't see that very often
:-)" -- Dave Mitchell, happy man.
Topics of Interest
"File::Path::mkpath()" incompatibility in perl-5.10
David Landgren replied to Jan Dubois on the subject of inodes on
Win32. "perlport" says the second value in the return list from "stat"
is always 0, and this throws off the code that detects race
conditions. As such, there's no way to determine if an attacker is
manipulating the filesystem for some nefarious purpose while a
long-running "rmtree()" call is running.
As it turns out, Windows filesystems may be intrinsically immune to
the attack, since you cannot move (or remove) a directory if any
process whatsoever has set their current working directory to it, or
any directory underneath it.
different strokes for different folks
http://xrl.us/bmj52
"Data::Dumper" patch
Earlier this month, Rafaël Garcia-Suarez applied a patch from Alexandr
Ciornii to get the bleading "Data::Dumper" to compile on older perls.
Dave Mitchell wondered whether C compilers understood Perl comments.
If not, this may mean that the patch needs patching.
slash that hash
http://xrl.us/bmj56
Change 30608 (17 March 2007)
Bram looked at change #30608, which involved commenting out a "study"
operation in op/taint.t. This results in the tests not really testing
what they set out to test.
He asked if anyone could recall why the line was commented out. No
takers, but I wonder if it has something to do with Yves Orton
discovering and UTF-8 and "study" studiously ignored each other in the
regexp engine.
http://xrl.us/bmj58
Consistent use of honor (instead of honour)
The British speller in me hates this idea.
but consistency has a lot going for it
http://xrl.us/bmj6a
"Module::Build" changes for VMS
John E. Malmberg revived the stranded changes for "Module::Build" that
were put aside in the lead up to 5.10.0. Essentially a number of
Unixisms needed to be excised from the code.
Craig A. Berry went through the changes with a fine-toothed comb and
picked up a number of glitches that needed work. John revised his work
and then had a patch ready for consideration by Ken Williams.
Craig found it hard to reconcile blead's "Module::Build" with Ken's
own repository. Ken found himself regretting Perforce's ability to
track the integration of patches. The plan at the end of the week was
to attack Ken's repository directly, and then dump something from that
back into blead.
John also figured out what was going wrong with "Archive::Tar"
creating an unopenable archive on VMS, which would have them within an
inch of having "Module::Build" build and test perfectly on VMS.
tales of the reconstruction
http://xrl.us/bmj6c
John detailed the "Archive::Tar" issue with VMS regarding
Module/Build/t/ppm.t in more detail in another thread. The problem
boils down to the different ways (stream and record oriented) that one
may employ to read a file on VMS. After this is fixed all that will be
needed is to mark VMS as having case-insensitive file names.
http://xrl.us/bmj6e
Confused about "close STDIN"
Bram was looking over an old bug report and trying to understand what
happens when one closes "STDIN", and wondered if the documentation for
"close" needed improvement.
Mark Mielke explained the difference between file descriptor 0 and the
"STDIN" file handle, which, through an extraordinary coincidence of
fate are usually the same, but sometimes aren't.
In which case, the documentation about "STDIN" needs to be worked on,
rather than "close".
closer
http://xrl.us/bmj6g
ext/POISX/t/sigaction.t failing under harness
(And the rest of the title of the thread is "...but not under test
(and not failing with threads under harness)"). Bram spent some time
working to reduce the problem down to the tiniest test case possible,
and in getting down to about five lines of real code, succeeded.
When he asked if anyone had an explanation for what was happening,
however, he met with less success.
http://xrl.us/bmj6i
TODO of the week
Something for a person with basic Perl skills.
Profile "installman"
The "installman" script is slow. All it is doing text processing,
which we're told is something Perl is good at. So it would be nice to
know what it is doing that is taking so much CPU, and where possible
address it.
(And there's a hot new profiler in town, "Devel::NYTProf").
Patches of Interest
Testing $/ with in memory files
Back in April, Bram had added some new regression tests for bug
#44833, that had itself been resolved many moons ago. At the time,
Rafaël applied them. Early in May, Ben Morrow suggested that Bram's
technique was not very cross-platform compatible, relying as it did on
a specific environment variable that specific Unix shells leave
behind. At the same time, Ben suggested a better internal-to-Perl
condition, so Bram rewrote the test to use that.
This week Bram pinged the list since the change still hadn't been
committed.
http://xrl.us/bmj6k
Recent lib.pm change imposes dual-life
Steffen Mïller was keen to see an updated lib.pm make it out to CPAN,
since that would allow him to upgrade older perl installations. This
in turn would stop "use lib 'foo.par'" from issuing a useless warning.
He tracked down Tim Bunce, who was listed as the current author. Tim
pleaded amnesia. Steffen took over maintenance, and posted a few
tweaks that would allow him to ready the module for a CPAN release.
Rafaël tweaked the license section to make it friendlier to license
lawyers.
lib liberation front
http://xrl.us/bmj6n
Watching the smoke signals
Smoke [5.11.0] 33949 FAIL(F) MSWin32 WinXP/.Net SP3 (x86/2 cpu)
Craig Berry glanced at one of Steve Hay's regular reports of smoke
failures to the list, and suggested he try one of Craig's own tweaks
to fix a failure that he had seen appearing on VMS.
preserving bits with File::Copy
http://xrl.us/bmj6p
New and old bugs from RT
Document behaviour when optional match does not match (#3589)
Reini Urban wrote a patch for "perlre" in an attempt to resolve an
eight year old bug report from Hugo van der Sanden, in which he was
misled by the documentation (or rather, its ambiguity) to think that
"babadad" =~ /^((.)?a\2)+$/
should succeed. Other porters explained the reasoning behind the
observed behaviour, and it was agreed that the documentation needed to
clarify this issue.
And so it came to pass that Reini added a paragraph to "perlre" to do
just that. Bram considered the explanation without looking at the bug
report, and admitted that he didn't have a clue as to what it meant.
needs work
http://xrl.us/bmj6r
\n after $ in regex (was: Strange regex failure?) (#35877)
As Bram continued his culling of RT issues, he came across the issue
of "qq[>10\n] =~ />\d+$ \n/ix" failing, where the original ticket
author thought it should succeed.
As it turns out, on 5.10 and beyond, it does in fact succeed. But then
Bram thought it might be worthwhile checking what happens when one
omits the "/x" modifier, and was surprised to see that it failed,
along with four other variations on a theme.
Zefram explained that this was to be expected, since the lack of
spaces meant that "dollar something" turned into a real Perl scalar
that contained something completely different, thus causing the match
to fail.
meta dollar
http://xrl.us/bmj6t
"sub foo(@$) {}" should generate an error (#36673)
Renée Bäcker thought that a prototyped function that has no body
should be an error. Rafaël thought so too, but said that he needed to
think about the ramifications a bit more. In the meantime, Renée
revised the path.
http://xrl.us/bmj6v
Certain string handling functions don't warn on undef (#36875)
Now that "uc", "lc" and the like warn if asked to operate on "undef",
Bram completed the picture by making "reverse undef" warn as well.
http://xrl.us/bmj6x
Threads + "require IO" causes segmentation fault (#37076)
Bram reported that this bug does not manifest itself on 5.8.9-tobe,
nor on 5.10 and beyond. He concluded that the bug had likely been
fixed, but asked for people on other platforms to take the test script
for a spin.
reflexions in a threaded perl
http://xrl.us/bmj6z
Back reference problem with quantified groups (#38133)
Bram supplied a TODO test for this problem, which was still waiting to
be applied at the end of the week.
http://xrl.us/bmj63
Fix bit-fields for VC ("GIMME_Vbroken" with 5.10.0/GCC and XS?) (#50386)
Dave Mitchell asked if the patch that resolved this bug was safe for
5.10.1, but Jan Dubois admitted that it wasn't binary compatible. But
it's not that bad, just a bit of bloat.
http://xrl.us/bmj65
Prototypes sneakily break :lvalue subs (#51408)
Rafaël Garcia-Suarez wondered if this problem could be solved through
some judicious tweaking of ENTERSUB flags.
http://xrl.us/bmj67
Doubled <meta http-equiv> header (#51542)
Renée supplied a patch to fix the two code paths in CGI.pm which could
lead to "<meta http-equiv>" headers being emitted twice.
http://xrl.us/bmj69
Trying to build perl5.8.3 under Maemo environment. (#53328)
After much to'ing and fro'ing, Bram managed to get Devendra Purbiya up
and running. A symbolic link for "pwd" did the trick.
http://xrl.us/bmj7b
Bug with "index()" matching beyond end of string when \0 bytes
(00000000) are involved (#53746)
Once he saw the TODO test, Dave Mitchell realised that there was a
really simple fix for the bug.
so he fixed it
http://xrl.us/bmj7d
"usethread=no" Configure compiler test file try.c is missing. (#54042)
H.Merijn Brand was puzzled as to why Reini Urban had only recently
begun (for some definition of recent) to encounter this error, since
the code in question has been touched in over a year. Andy Dougherty
suspected that something must have changed in Reini's setup, to
trigger a walk down a previously unvisited codepath.
Reini concurred, saying that an upgrade to cygwin2.dll could have
changed the result from a "fflush(NULL)" call, which is what tripped
up "Configure".
all fixed
http://xrl.us/bmj7f
Double free or corruption using threads and goto (#54756)
Luis Lencina reported this problem on 5.8.8, but Dave Mitchell was
unable to reproduce it on 5.10 and beyond.
a good reason to upgrade
http://xrl.us/bmj7h
Perl 5.10 memory corruption (#54758)
George Greer reported a problem with in-place sorts on 5.10. Rafaël
tried to diagnose the problem, and Moritz Lenz tried to bisect the
error to determine what patch caused the error. But while they were
trying to work things out, Dave Mitchell strolled by and tweaked a
couple of spots in pp_sort.c.
George was happy to report that Dave's patch corrected his cut-down
test, as well as the real-life code from whence the problem came.
wrap it up as a test
http://xrl.us/bmkmo
perlio.c has a problem (both 5.8 and 5.10) (#54828)
Goro Fuji reported an issue with "PerlIORaw_pushed()" and offered a
patch to fix things up. Rafaël Garcia-Suarez agreed with the reasoning
and applied one part of the patch. For the second part, he deferred to
people with more experience with Windows, since he wasn't sure why it
was needed.
http://xrl.us/bmj7j
Perl 5.10 segmentation fault using "Net::SSH2::Channel" (#54908)
Sebastien Rodriguez suffered segmentation faults with 5.10 when trying
to use this module. Steve Peters built the module, and was alarmed by
the number of compiler warnings it emitted. He also saw it fail an
assertion.
Ævar Arnfjörð Bjarmason traced the problem down to the fact that it
used the PV slot of a GV to store a pointer to a custom data
structure, which reminded him of "Math::Pari" (another module that
gave the porters grief a few weeks back).
On IRC, the concensus was that it would be very difficult to tweak the
core to play nicely with the module, so the module will just have to
adapt. What is more, despite the extensive test campaign that the
porters conducted, it turns out that the test suite itself was
hopelessly inadequate, since it passed, and yet the most basic real
usage failed.
Which also meant that not a single person had tried 5.9.x with the
module in the months leading up to 5.10.
so when we say test, TEST!
http://xrl.us/bmj7m
IO on active pipes fails after ithread fork in 5.8.8 (#54926)
John Heidemann wrote about a simple program that performs differently
depending on how it is run:
cat data | prog
# or
prog <data
Specifically, according to "strace", the internals perform an "lseek"
after spinning off a new thread, and this appears to fail in the first
example.
that's not supposed to happen
http://xrl.us/bmj7o
Attempt to free unreferenced scalar fiddling with the symbol table (#54934)
Niko Tyni showed a tiny program that demonstrated a larger problem
that occurs when one tries to blow away a dynamically created package.
I give him bonus points for taking the time to bisect the change log
and isolate the offending patch.
Armed with that information, Rafaël Garcia-Suarez was able to supply a
patch that fixed up the problem, but he had a sneaking feeling that it
might cause a memory leak. Alex Vandiver was pretty pleased, since a
corollary of the bug fix was that SVK no longer segfaults on 5.10 and
blead.
heads up for 5.10.1
http://xrl.us/bmj7q
Building 5.6.2 Fails with -Duseshrplib on Leopard (#54952)
David Wheeler had problems with a build of 5.6.2, and despite its
exceptional old age, a number of porters spent a surprising amount of
time trying to figure out why it had stopped working and what one
might to be able to do in order to get it working again.
it's dead Jim
http://xrl.us/bmj7u
Crash on binary-or lvalue operation on "qr//" (#54956)
Steve Peters delved further into this problem and discovered that "&="
fails in the same way (which means "^=" is probably a likely bet too)
and any sort of reference to a non-numeric scalar would suffice.
He graciously stepped aside to wait in case anyone felt like jumping
in and fixing it. He can dream, right?
no, after you
http://xrl.us/bmj7w
Strange "map {}" behavior when returning two values (#54974)
David Wheeler was bitten by the tokeniser choosing between a code
block and an anonymous hash and taking the wrong decision. The
disambiguation involves using a leading semi-colon or parentheses.
Debate raged as to what would be clearest to a maintenance programmer
of little brain.
http://xrl.us/bmj7y
Initial make failing, but don't know why (#55008)
Steve Michel was mystified by a build failing. Andy Dougherty was
quite puzzled as well, but thought some of the configure switches
seemed a little unusual. Jim Cromie pinged the list about his patch
from last year that would outlaw unrecognised switches.
http://xrl.us/bmj72
Problem with porting perl on Armel (#55038)
Devendra Purbiya continued to have build troubles, this time on an ARM
platform. All sorts of weird failures were encountered. Bram patiently
walked Devendra through a series of steps to try and get to the bottom
of the issues.
http://xrl.us/bmj74
Debugger loops infinitely with "__DIE__" and "DESTROY" (#55084)
Peter Scott showed a nifty technique to give the debugger a bad case
of indigestion, and traced the problem all the way back to 5.004.
time to die
http://xrl.us/bmj76
Perl5 Bug Summary
Hey, we cracked he 1600 barrier!
280 new + 1309 open = 1589 (+12 -54)
http://xrl.us/bmj78
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
New Core Modules
Thread::Queue 2.09
Jerry D. Hedden pushed a new version out that deals more
gracefully with older perls.
http://xrl.us/bmj8a
In Brief
Andreas König filed bug #54776 concerning a failure with
"Archive::Extract" on 5.10.1-tobe, and then later reported that change
#33470 corrected the problem.
http://xrl.us/bmj8c
Renée Bäcker found some tickets in RT that had patches ready for the
picking, as well as some more that could be closed.
low hanging fruit
http://xrl.us/bmj8e
Renée also supplied documentation for attributes.pm to render it less
recursive and incomplete (bug #36516)
http://xrl.us/bmj8g
H.Merijn Brand found some warnings in a Unicode test environment when
dealing with "Module::Build".
nasty unexpected non-continuation bytes, we hates them
http://xrl.us/bmj8i
Steve Peters added some more "-fstack-protector" goodness. (bug
#54120)
http://xrl.us/bmj8k
H.Merijn Brand issued a ping for "Math::Complex" regarding smoke
failures on HP-UX. Since maintenance is currently in a state of flux,
somewhere between Jarkko Hietaniemi and Zefram, the message went
adrift.
http://xrl.us/bmj8v
Andy Dougherty and Craig Berry managed to propagate new i_gdbm*ndbm
variables somewhere in the depths of Configure.
http://xrl.us/bmj8x
Last week's summary
I think these must have got wedged in a moderator queue somewhere.
This Week on perl5-porters - 11-17 May 2008
http://xrl.us/bmj8z
This Week on perl5-porters - 18-24 May 2008
http://xrl.us/bmj83
About this summary
This summary was written by David Landgren.
Weekly summaries are published on http://use.perl.org/ and posted on a
mailing list, (subscription: [EMAIL PROTECTED]). The
archive is at http://dev.perl.org/perl5/list-summaries/. Corrections
and comments are welcome.
If you found this summary useful, please consider contributing to the
Perl Foundation or attending a YAPC to help support the development of
Perl.
--
stubborn tiny lights vs. clustering darkness forever ok?
