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[perl #51072] Method dispatch breaks with defined(\&sub)
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From:
nagler @ bivio . biz
Date:
February 21, 2008 08:08
Subject:
[perl #51072] Method dispatch breaks with defined(\&sub)
Message ID:
rt-3.6.HEAD-29454-1203609388-1585.51072-75-0@perl.org
# New Ticket Created by nagler@bivio.biz
# Please include the string: [perl #51072]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=51072 >
This is a bug report for perl from nagler@bivio.biz,
generated with the help of perlbug 1.35 running under perl v5.8.5.
-----------------------------------------------------------------
[Please enter your report here]
From: Rob Nagler <nagler@bivio.biz>
To: boulder-pm@pm.org
Subject: Re: [Boulder.pm] mod_perl package lexicals becoming corrupt
Date: Wed, 20 Feb 2008 12:49:32 -0700
Found the bug. Here's what demonstrates it:
package T1;
use strict;
sub s1 {}
package T2;
use base 'T1';
use strict;
package main;
T2->s1;
print("ok\n");
\&T2::s1;
print("not reached\n");
T2->s1;
The \&T2:s1 autovivifies something in the package hash, which is
"nasty", and actually ends up corrupting the package hash so that
lexicals disappear. We had a function called super_for_method, which
did this:
foreach my $a (@{$proto->inheritance_ancestors}) {
my($sub) = \&{$a . '::' . $method};
next unless defined(&$sub);
return ($sub, $a);
}
The fact that \&{} seems to autovivify an invalid package hash entry
is the problem. You can implement the above this way:
foreach my $a (@{$proto->inheritance_ancestors}) {
my($sub) = $a . '::' . $method;
do {
no strict 'refs';
next unless defined(&$sub);
};
return (\&$sub, $a);
}
The above code does not corrupt the the package hash. Both pieces of
code autovivify the glob for $sub, but in the former case, the
autovivification has a dangerous side effect of corrupting the entire
symbol table (in a subtle way, of course, which is why I got confused
by the number of lexicals).
Rob
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=medium
---
This perlbug was built using Perl v5.8.5 in the Red Hat build system.
It is being executed now by Perl v5.8.5 - Wed Nov 7 16:36:26 EST 2007.
Site configuration information for perl v5.8.5:
Configured by Red Hat, Inc. at Wed Nov 7 16:36:26 EST 2007.
Summary of my perl5 (revision 5 version 8 subversion 5) configuration:
Platform:
osname=linux, osvers=2.6.9-55.0.9.elsmp, archname=i386-linux-thread-multi
uname='linux builder4.centos.org 2.6.9-55.0.9.elsmp #1 smp thu sep 27 18:27:41 edt 2007 i686 i686 i386 gnulinux '
config_args='-des -Doptimize=-O2 -g -pipe -m32 -march=i386 -mtune=pentium4 -Dversion=5.8.5 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dinc_version_list=5.8.4 5.8.3 5.8.2 5.8.1 5.8.0'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=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 ='-D_REENTRANT -D_GNU_SOURCE -DDEBUGGING -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
optimize='-O2 -g -pipe -m32 -march=i386 -mtune=pentium4',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBUGGING -fno-strict-aliasing -pipe -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.4.6 20060404 (Red Hat 3.4.6-8)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='gcc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=/lib/libc-2.3.4.so, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.4'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.8.5/i386-linux-thread-multi/CORE'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.8.5:
/home/nagler/src/perl
/usr/lib/perl5/5.8.5/i386-linux-thread-multi
/usr/lib/perl5/5.8.5
/usr/lib/perl5/site_perl/5.8.5/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.4/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.2/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.5
/usr/lib/perl5/site_perl/5.8.4
/usr/lib/perl5/site_perl/5.8.3
/usr/lib/perl5/site_perl/5.8.2
/usr/lib/perl5/site_perl/5.8.1
/usr/lib/perl5/site_perl/5.8.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.8.5/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.4/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.2/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.5
/usr/lib/perl5/vendor_perl/5.8.4
/usr/lib/perl5/vendor_perl/5.8.3
/usr/lib/perl5/vendor_perl/5.8.2
/usr/lib/perl5/vendor_perl/5.8.1
/usr/lib/perl5/vendor_perl/5.8.0
/usr/lib/perl5/vendor_perl
.
---
Environment for perl v5.8.5:
HOME=/home/nagler
LANG=en_US.UTF-8
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/usr/java/jdk1.5.0_14/bin:/home/nagler/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/local/oracle/product/8.1.6/bin:/home/nagler/bin
PERLLIB=/home/nagler/src/perl
PERL_BADLANG (unset)
PERL_MM_OPT=PREFIX=/home/nagler INSTALLMAN1DIR=/home/nagler/man/man1 INSTALLMAN3DIR=/home/nagler/man/man3
SHELL=/bin/bash
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[perl #51072] Method dispatch breaks with defined(\&sub)
by nagler @ bivio . biz