CORE::select ignoring timeout var's magic #13332

p5pRT · 2013-10-04T21:10:47Z

Migrated from rt.perl.org#120102 (status was 'resolved')

Searchable as RT120102$

p5pRT · 2013-10-04T21:10:47Z

From @sanko

This is a bug report for perl from sanko@cpan.org,
generated with the help of perlbug 1.39 running under perl 5.16.3.

Hi!

I've found that CORE::select($$$$) mishandles magical timeout values
unless the var is used by some other means first. A minimum example
of this:

use Tie::Scalar;
tie (my $SLEEP_TIME, 'Tie::StdScalar', 0.25);
#print $SLEEP_TIME; # Uncomment this and select works just fine
select (undef, undef, undef, $SLEEP_TIME);

This blocks indefinitely rather than the quarter second sleep I expect.

An example from dave_the_m shows that it isn't tie()-specific:

"5" =~ /(\d)/;
#my $x = $1; # Uncomment this and select works just fine
select (undef, undef, undef, $1);

Note that if the commented lines are uncommented in the above examples,
select works as is should.

Original discussion found on PerlMonks: perlmonks.org/?node_id=1056913

Flags:
category=core
severity=high

Site configuration information for perl 5.16.3:

Configured by strawberry-perl at Tue Mar 12 13:56:09 2013.

Summary of my perl5 (revision 5 version 16 subversion 3) configuration:

Platform:
osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread
uname='Win32 strawberry-perl 5.16.3.1 #1 Tue Mar 12 13:55:20 2013 i386'
config_args='undef'
hint=recommended, useposix=true, d_sigaction=undef
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=undef, use64bitall=undef, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='gcc', ccflags =' -s -O2 -DWIN32 -DPERL_TEXTMODE_SCRIPTS
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fno-strict-aliasing
-mms-bitfields',
optimize='-s -O2',
cppflags='-DWIN32'
ccversion='', gccversion='4.6.3', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='long long',
lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='g++', ldflags ='-s -L"C:\strawberry\perl\lib\CORE"
-L"C:\strawberry\c\lib"'
libpth=C:\strawberry\c\lib C:\strawberry\c\i686-w64-mingw32\lib
libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
libc=, so=dll, useshrplib=true, libperl=libperl516.a
gnulibc_version=''
Dynamic Linking:
dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
cccdlflags=' ', lddlflags='-mdll -s -L"C:\strawberry\perl\lib\CORE"
-L"C:\strawberry\c\lib"'

Locally applied patches:

@INC for perl 5.16.3:
C:/strawberry/perl/site/lib/MSWin32-x86-multi-thread
C:/strawberry/perl/site/lib
C:/strawberry/perl/vendor/lib
C:/strawberry/perl/lib
.

Environment for perl 5.16.3:
HOME=C:\Users\Sanko
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)

PATH=C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\strawberry\c\bin;C:\strawberry\perl\site\bin;C:\strawberry\perl\bin;C:\Ruby193\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program
Files\Mercurial;C:\strawberry\c\bin;C:\strawberry\perl\site\bin;C:\strawberry\perl\bin;C:\Program
Files\Python32\Lib\site-packages\PyQt4;C:\Program Files\Prio;C:\Program
Files\git-cola\bin;C:\Program Files\Git\cmd;C:\Program Files\Git\bin;;
PERL_BADLANG (unset)
PERL_CPANM_OPT=--mirror http://cpan.cpantesters.org --verbose --notest
--force
SHELL (unset)
--
Sanko Robinson
sanko@cpan.org

p5pRT · 2013-10-04T23:15:34Z

From @jkeenan

On Fri Oct 04 14:10:47 2013, sanko wrote:

This is a bug report for perl from sanko@cpan.org,
generated with the help of perlbug 1.39 running under perl 5.16.3.

-----------------------------------------------------------------
Hi!

I've found that CORE::select($$$$) mishandles magical timeout values
unless the var is used by some other means first. A minimum example
of this:
use Tie&#8203;::Scalar;
tie $my $SLEEP\_TIME\, 'Tie&#8203;::StdScalar'\, 0\.25$;
\#print $SLEEP\_TIME; \# Uncomment this and select works just fine
select $undef\, undef\, undef\, $SLEEP\_TIME$;
This blocks indefinitely rather than the quarter second sleep I
expect.

An example from dave_the_m shows that it isn't tie()-specific:
"5" =~ /$\\d$/;
\#my $x = $1; \# Uncomment this and select works just fine
select $undef\, undef\, undef\, $1$;
Note that if the commented lines are uncommented in the above
examples,
select works as is should.

Original discussion found on PerlMonks: perlmonks.org/?node_id=1056913

Additional data, run on blead on Dromedary:

Both of the following work:

#########
"5" =~ /(\d)/;
my $x = $1;
select (undef, undef, undef, $1);
print "Done 1\n";

my $y = 5;
select (undef, undef, undef, $y);
print "Done 2\n";
#########

Thank you very much.
Jim Keenan

p5pRT · 2013-10-04T23:15:35Z

The RT System itself - Status changed from 'new' to 'open'

p5pRT · 2013-10-05T00:44:59Z

From @ikegami

Patch attached.

On Fri, Oct 4, 2013 at 7:15 PM, James E Keenan via RT <
perlbug-followup@perl.org> wrote:

On Fri Oct 04 14:10:47 2013, sanko wrote:
This is a bug report for perl from sanko@cpan.org,
generated with the help of perlbug 1.39 running under perl 5.16.3.

-----------------------------------------------------------------
Hi!

I've found that CORE::select($$$$) mishandles magical timeout values
unless the var is used by some other means first. A minimum example
of this:
use Tie&#8203;::Scalar;
tie $my $SLEEP\_TIME\, 'Tie&#8203;::StdScalar'\, 0\.25$;
\#print $SLEEP\_TIME; \# Uncomment this and select works just fine
select $undef\, undef\, undef\, $SLEEP\_TIME$;
This blocks indefinitely rather than the quarter second sleep I
expect.

An example from dave_the_m shows that it isn't tie()-specific:
"5" =~ /$\\d$/;
\#my $x = $1; \# Uncomment this and select works just fine
select $undef\, undef\, undef\, $1$;
Note that if the commented lines are uncommented in the above
examples,
select works as is should.

Original discussion found on PerlMonks: perlmonks.org/?node_id=1056913
Additional data, run on blead on Dromedary:

Both of the following work:

#########
"5" =~ /(\d)/;
my $x = $1;
select (undef, undef, undef, $1);
print "Done 1\n";

my $y = 5;
select (undef, undef, undef, $y);
print "Done 2\n";
#########

Thank you very much.
Jim Keenan

---
via perlbug: queue: perl5 status: new
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=120102

p5pRT · 2013-10-05T00:44:59Z

From @ikegami

0001-Call-select-s-4th-arg-s-magic.patch

From f27c6568d352c694815e5e1ed29fe30c993deef7 Mon Sep 17 00:00:00 2001
From: Eric Brine <ikegami@adaelis.com>
Date: Fri, 4 Oct 2013 17:42:34 -0700
Subject: [PATCH] Call select's 4th arg's magic

---
 pp_sys.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/pp_sys.c b/pp_sys.c
index 5656e5a..a7ab233 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -1159,6 +1159,7 @@ PP(pp_sselect)
 #  endif
 
     sv = SP[4];
+    SvGETMAGIC(sv);
     if (SvOK(sv)) {
 	value = SvNV(sv);
 	if (value < 0.0)
-- 
1.7.2.5

p5pRT · 2013-10-05T01:04:45Z

From @bulk88

On Fri Oct 04 17:44:59 2013, ikegami@adaelis.com wrote:

Patch attached.

The patch isn't the best. A SvGETMAGIC is added, and then SvNV (another
get magic call) is made. SvNV_nomg and other *_nomg (if any) need to be
used later on.

--
bulk88 ~ bulk88 at hotmail.com

p5pRT · 2013-10-05T04:56:02Z

From @ikegami

On Fri, Oct 4, 2013 at 9:04 PM, bulk88 via RT <perlbug-followup@perl.org>wrote:

On Fri Oct 04 17:44:59 2013, ikegami@adaelis.com wrote:

Patch attached.

The patch isn't the best. A SvGETMAGIC is added, and then SvNV (another
get magic call) is made. SvNV_nomg and other *_nomg (if any) need to be
used later on.

Oops, been a while. Updated patch attached. That's the only other time that
scalar is accessed.

p5pRT · 2013-10-05T04:56:02Z

From @ikegami

0001-Call-select-s-4th-arg-s-magic.patch

From ce86b68b2ced2b12047b58e07b37d9128a9bb1eb Mon Sep 17 00:00:00 2001
From: Eric Brine <ikegami@adaelis.com>
Date: Fri, 4 Oct 2013 17:42:34 -0700
Subject: [PATCH] Call select's 4th arg's magic

---
 pp_sys.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/pp_sys.c b/pp_sys.c
index 5656e5a..b5ed33f 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -1159,8 +1159,9 @@ PP(pp_sselect)
 #  endif
 
     sv = SP[4];
+    SvGETMAGIC(sv);
     if (SvOK(sv)) {
-	value = SvNV(sv);
+	value = SvNV_nomg(sv);
 	if (value < 0.0)
 	    value = 0.0;
 	timebuf.tv_sec = (long)value;
-- 
1.7.2.5

p5pRT · 2013-10-18T15:22:15Z

From @iabyn

On Sat, Oct 05, 2013 at 12:55:26AM -0400, Eric Brine wrote:

On Fri, Oct 4, 2013 at 9:04 PM, bulk88 via RT <perlbug-followup@perl.org>wrote:

On Fri Oct 04 17:44:59 2013, ikegami@adaelis.com wrote:

Patch attached.

The patch isn't the best. A SvGETMAGIC is added, and then SvNV (another
get magic call) is made. SvNV_nomg and other *_nomg (if any) need to be
used later on.

Oops, been a while. Updated patch attached. That's the only other time that
scalar is accessed.

Thanks, applied as

90eaaf0

I added a test in the same commit.

--
Standards (n). Battle insignia or tribal totems.

p5pRT · 2013-10-18T15:23:09Z

@iabyn - Status changed from 'open' to 'resolved'

p5pRT closed this as completed Oct 18, 2013

p5pRT added Severity Low type-OS-interaction labels Oct 19, 2019

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CORE::select ignoring timeout var's magic #13332

CORE::select ignoring timeout var's magic #13332

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CORE::select ignoring timeout var's magic #13332

CORE::select ignoring timeout var's magic #13332

Comments

p5pRT commented Oct 4, 2013

p5pRT commented Oct 4, 2013

From @sanko

p5pRT commented Oct 4, 2013

From @jkeenan

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From @ikegami

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From @bulk88

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From @iabyn

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