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[mp2] [BUG] Segfault with Test::More - duping STDOUT?

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merlyn.kline at jobsite

Dec 6, 2011, 9:40 AM

Views: 809
[mp2] [BUG] Segfault with Test::More - duping STDOUT?

(I have read the bug reporting guides but unfortunately cannot follow all the instructions because I am missing Apache::TestReportPerl and do not have the necessary permissions to install it, nor to rebuild perl with debugging turned on. Hopefully I have provided enough information.)

I have discovered that simply "use"ing Test::More in a mod_perl script causes my apache to segfault. I originally reported this to the author of Test::More (see https://rt.cpan.org/Public/Bug/Display.html?id=69687) but now believe the problem to have wider scope. By progressively removing code from my original example I have reduced it to the trivial example that follows.

To REPRODUCE the problem, you need a Broken.pm module like this:

package Broken;
my $Testout;
create(); sub create { # Insert "{#" at the start of this line and the segfault goes away
open( $Testout, ">&STDOUT" ) or die "Can't dup STDOUT: $!";

and a script like this:

#!/usr/bin/perl -w

use Broken;

print "Content-Type: text/html\r\n\r\nhello ";
open TEST, "|/bin/cat";
close TEST;
print "world\n";

Holding down F5 to generate reloads soon causes a segfault (my server is configured for five mod_perl processes).

Note that if the code to dup STDOUT is not in a sub then the fault seems to go away.

Apache, mod_perl and perl version info appended.

I have found a similar(ish) report at http://http://stackoverflow.com/questions/4413411/ but no resolution. Note that removing from my example the code that opens the pipe to cat, solves the problem - this is the similarity here (and I realise that's likely a red herring).

Merlyn Kline

Apache/2.2.15 (Unix) DAV/2 mod_ssl/2.2.15 OpenSSL/1.0.0-fips mod_perl/2.0.4 Perl/v5.10.1 configured -- resuming normal operations

Summary of my perl5 (revision 5 version 10 subversion 1) configuration:

osname=linux, osvers=2.6.18-194.26.1.el5, archname=x86_64-linux-thread-multi
uname='linux x86-003.build.bos.redhat.com 2.6.18-194.26.1.el5 #1 smp fri oct 29 14:21:16 edt 2010 x86_64 x86_64 x86_64 gnulinux '
config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -DDEBUGGING=-g -Dversion=5.10.1 -Dmyhostname=localhost -Dperladmin=root [at] localhos -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl5 -Dsitearch=/usr/local/lib64/perl5 -Dprivlib=/usr/share/perl5 -Darchlib=/usr/lib64/perl5 -Dvendorlib=/usr/share/perl5/vendor_perl -Dvendorarch=/usr/lib64/perl5/vendor_perl -Dinc_version_list=5.10.0 -Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64 -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto -Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto -Ud_endservent_r_proto -Ud_setservent_r_proto -Dscriptdir=/usr/bin'
hint=recommended, useposix=true, d_sigaction=define
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic',
cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.4.4 20100726 (Red Hat 4.4.4-13)', gccosandvers=''
intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='gcc', ldflags =' -fstack-protector'
libpth=/usr/local/lib64 /lib64 /usr/lib64
libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=, so=so, useshrplib=true, libperl=libperl.so
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib64/perl5/CORE'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic'

Characteristics of this binary (from libperl):
Built under linux
Compiled at Apr 19 2011 15:27:31

Subject User Time
[mp2] [BUG] Segfault with Test::More - duping STDOUT? merlyn.kline at jobsite Dec 6, 2011, 9:40 AM
    Re: [mp2] [BUG] Segfault with Test::More - duping STDOUT? bac2bac at bac2bac Dec 7, 2011, 2:37 AM
        Re: [mp2] [BUG] Segfault with Test::More - duping STDOUT? torsten.foertsch at gmx Dec 7, 2011, 4:23 AM
    Re: [mp2] [BUG] Segfault with Test::More - duping STDOUT? torsten.foertsch at gmx Dec 7, 2011, 4:33 AM

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