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[perl #108792] Since perl5.14, prctl is used to modify the process name through $0. prctl may have issues on older kernel

Iker Salmón San Millán
January 22, 2012 15:16
[perl #108792] Since perl5.14, prctl is used to modify the process name through $0. prctl may have issues on older kernel
Message ID:
# New Ticket Created by  Iker Salmón San Millán 
# Please include the string:  [perl #108792]
# in the subject line of all future correspondence about this issue. 
# <URL: >

[Please describe your issue here]
TRying to cross-debootstrap from x86 system to armhf i get an error
configuring cron:
Setting up cron (3.0pl1-120+b1) ...
Can't set $0 with prctl(): Bad address at /usr/sbin/addgroup line 86.

related /usr/sbin/addgroup lines:

85    my $nogroup_id = getgrnam("nogroup") || 65534;
86    $0 =~ s+.*/++;
88    our $verbose = 1;        # should we be verbose?

this does not happen if the target rootfs is armel instead of armhf.  I've
been discussing (asking for help better said),
in arm-debian-mailing list and they 've pointed me in this direction.

Dominic Dumont said:
Well, according to perlvar(1) (look for \$0), modifying $0 is not portable.
(In this case, I don't see the point: addgroup program is short lived, hence
shortening the process name is not likely to be useful.)

Since perl5.14, prctl is used to modify the process name through $0. prctl
have issues on older kernel.

This may be a perl 5.14 bug. OTOH, changing $0 in addgroup is a bad idea.

The weird thing is if i install and amd64 kernel in my x86 system and try
to debootstrap everithing works fine.
So, this bug may be only reproducible in x86 systems with 686 (or below)



[Please do not change anything below this line]
Site configuration information for perl 5.14.2:

Configured by Debian Project at Mon Nov 28 21:49:25 UTC 2011.

Summary of my perl5 (revision 5 version 14 subversion 2) configuration:

    osname=linux, osvers=2.6.32-5-686,
    uname='linux callisto 2.6.32-5-686 #1 smp mon oct 3 04:15:24 utc 2011
i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.14 -Darchlib=/usr/lib/perl/5.14
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitearch=/usr/local/lib/perl/5.14.2 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm
-Ui_libutil -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.6.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/i386-linux-gnu /lib/../lib
/usr/lib/i386-linux-gnu /usr/lib/../lib /lib /usr/lib /usr/lib64
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true,
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib

Locally applied patches:

@INC for perl 5.14.2:

Environment for perl 5.14.2:
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)
    SHELL=/bin/bash Perl Programming lists via nntp and http.
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