develooper Front page | perl.perl5.porters | Postings from February 2003

[perl #20727] Segfault in program mingling tie and select

From:
perlbug-followup
Date:
February 5, 2003 10:22
Subject:
[perl #20727] Segfault in program mingling tie and select
Message ID:
rt-20727-50341.1.83440818897864@bugs6.perl.org
# New Ticket Created by  Gregor N. Purdy 
# Please include the string:  [perl #20727]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=20727 >



This is a bug report for perl from gregor@focusresearch.com,
generated with the help of perlbug 1.34 running under perl v5.8.0.


-----------------------------------------------------------------
[Please enter your report here]

The program below segfaults. While I would not be surprised that
it doesn't behave well, segfaulting is a more severe misbehaviour
than I would have expected.

I was exploring the possiblity of a module that made select()
into a variable to be frobbed rather than a builtin sub to be
called. I do not assert that the program below is a correct
implementation of that idea, only that it segfaults.


#!/usr/bin/perl -w
#
# tie-segfault.pl
#
# 2001-09-11: Genesis.
#
# Copyright (C) 2001-2003 Gregor N. Purdy. All rights reserved.
# This program is free software. It is subject to the same license as Perl.
#

use strict;

package File::select;

sub TIESCALAR
{
  my $class = shift; my $self = select();
  return bless \$self, $class
}

sub FETCH { return select(); }
sub STORE { my $self = shift; select(shift); return select(); }

package main;

use vars qw($SELECT); tie $SELECT, 'File::select';

$SELECT = *STDERR;                   # Commenting out this line stops segfault
print STDOUT $SELECT, "\n";          # Commenting out this (typo) line stops segfault
#print $SELECT "Howdy (on STDERR)\n"; # This is what the above should have been.
{ local $SELECT = *STDOUT; }


[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=high
---
Site configuration information for perl v5.8.0:

Configured by bhcompile at Sun Sep  1 23:55:07 EDT 2002.

Summary of my perl5 (revision 5.0 version 8 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.4.18-11smp, archname=i386-linux-thread-multi
    uname='linux daffy.perf.redhat.com 2.4.18-11smp #1 smp thu aug 15 06:41:59 edt 2002 i686 i686 i386 gnulinux '
    config_args='-des -Doptimize=-O2 -march=i386 -mcpu=i686 -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'
    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 -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -march=i386 -mcpu=i686',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/usr/include/gdbm'
    ccversion='', gccversion='3.2 20020822 (Red Hat Linux Rawhide 3.2-5)', 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=-lnsl -lgdbm -ldb -ldl -lm -lpthread -lc -lcrypt -lutil
    perllibs=-lnsl -ldl -lm -lpthread -lc -lcrypt -lutil
    libc=/lib/libc-2.2.92.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.2.92'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/usr/lib/perl5/5.8.0/i386-linux-thread-multi/CORE'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.0:
    /home/gregor/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /home/gregor/lib/perl5/site_perl/5.8.0
    /home/gregor/lib/perl5/site_perl/5.6.1
    /home/gregor/lib/perl5/site_perl
    /usr/lib/perl5/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/5.8.0
    /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl/5.6.1
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl/5.6.1
    /usr/lib/perl5/vendor_perl
    .

---
Environment for perl v5.8.0:
    HOME=/home/gregor
    LANG=en_US.iso885915
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/usr/local/src/xml-xalan/c/lib:/usr/local/src/Sablot-0.44/lib
    LOGDIR (unset)
    PATH=.:/home/gregor/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/java/jdk1.3.1/bin:/usr/lib/ICAClient:/opt/ant/bin:/home/gregor/bin:.
    PERL5LIB=/home/gregor/lib/perl5/site_perl
    PERL_BADLANG (unset)
    SHELL=/bin/bash




nntp.perl.org: Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at ask@perl.org | Group listing | About