keys %SIG contains 'SIGUNUSED'

[p5pRT]

Migrated from rt.perl.org#132631 (status was 'rejected')

Searchable as RT132631$

[p5pRT]

From @jimav

This is a bug report for perl from jim.avera@​gmail.com,
generated with the help of perlbug 1.40 running under perl 5.26.0.

---

$ perl -we 'local @​SIG{ keys %SIG };'
No such signal​: SIGUNUSED at -e line 1.
No such signal​: SIGUNUSED at -e line 1.

There is an easy work-around, namely localizing only the specific
signals which are about to be temporarily changed (e.g. HUP INT TERM)
(and setting any to undef has, I guess, undefined effects).

However something isn't right if there is a key in %SIG which
can not be used for anything.

---

---

Flags​:
  category=core
  severity=low

---

Site configuration information for perl 5.26.0​:

Configured by Debian Project at Fri Sep 15 16​:13​:42 UTC 2017.

Summary of my perl5 (revision 5 version 26 subversion 0) configuration​:
 
  Platform​:
  osname=linux
  osvers=4.9.0
  archname=x86_64-linux-gnu-thread-multi
  uname='linux localhost 4.9.0 #1 smp debian 4.9.0 x86_64 gnulinux '
  config_args='-Dusethreads -Duselargefiles -Dcc=x86_64-linux-gnu-gcc -Dcpp=x86_64-linux-gnu-cpp -Dld=x86_64-linux-gnu-gcc -Dccflags=-DDEBIAN -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fdebug-prefix-map=/build/perl-4JQEGJ/perl-5.26.0=. -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-Bsymbolic-functions -Wl,-z,relro -Dlddlflags=-shared -Wl,-Bsymbolic-functions -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.26 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.26 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.26 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.26.0 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.26.0 -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 -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -dEs -Duseshrplib -Dlibperl=libperl.so.5.26.0'
  hint=recommended
  useposix=true
  d_sigaction=define
  useithreads=define
  usemultiplicity=define
  use64bitint=define
  use64bitall=define
  uselongdouble=undef
  usemymalloc=n
  default_inc_excludes_dot=define
  bincompat5005=undef
  Compiler​:
  cc='x86_64-linux-gnu-gcc'
  ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
  optimize='-O2 -g'
  cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include'
  ccversion=''
  gccversion='7.2.0'
  gccosandvers=''
  intsize=4
  longsize=8
  ptrsize=8
  doublesize=8
  byteorder=12345678
  doublekind=3
  d_longlong=define
  longlongsize=8
  d_longdbl=define
  longdblsize=16
  longdblkind=3
  ivtype='long'
  ivsize=8
  nvtype='double'
  nvsize=8
  Off_t='off_t'
  lseeksize=8
  alignbytes=8
  prototype=define
  Linker and Libraries​:
  ld='x86_64-linux-gnu-gcc'
  ldflags =' -fstack-protector-strong -L/usr/local/lib'
  libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
  libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
  perllibs=-ldl -lm -lpthread -lc -lcrypt
  libc=libc-2.26.so
  so=so
  useshrplib=true
  libperl=libperl.so.5.26
  gnulibc_version='2.26'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs
  dlext=so
  d_dlsymun=undef
  ccdlflags='-Wl,-E'
  cccdlflags='-fPIC'
  lddlflags='-shared -L/usr/local/lib -fstack-protector-strong'

Locally applied patches​:
  DEBPKG​:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
  DEBPKG​:debian/db_file_ver - https://bugs.debian.org/340047 Remove overly restrictive DB_File version check.
  DEBPKG​:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.
  DEBPKG​:debian/enc2xs_inc - https://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @​INC directories.
  DEBPKG​:debian/errno_ver - https://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
  DEBPKG​:debian/libperl_embed_doc - https://bugs.debian.org/186778 Note that libperl-dev package is required for embedded linking
  DEBPKG​:fixes/respect_umask - Respect umask during installation
  DEBPKG​:debian/writable_site_dirs - Set umask approproately for site install directories
  DEBPKG​:debian/extutils_set_libperl_path - EU​:MM​: set location of libperl.a under /usr/lib
  DEBPKG​:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor
  DEBPKG​:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.
  DEBPKG​:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.
  DEBPKG​:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.
  DEBPKG​:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.
  DEBPKG​:debian/mod_paths - Tweak @​INC ordering for Debian
  DEBPKG​:debian/prune_libs - https://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
  DEBPKG​:debian/perlivp - https://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
  DEBPKG​:debian/deprecate-with-apt - https://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules
  DEBPKG​:debian/squelch-locale-warnings - https://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
  DEBPKG​:debian/skip-upstream-git-tests - Skip tests specific to the upstream Git repository
  DEBPKG​:debian/patchlevel - https://bugs.debian.org/567489 List packaged patches for 5.26.0-8ubuntu1 in patchlevel.h
  DEBPKG​:fixes/document_makemaker_ccflags - https://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}
  DEBPKG​:debian/find_html2text - https://bugs.debian.org/640479 Configure CPAN​::Distribution with correct name of html2text
  DEBPKG​:debian/perl5db-x-terminal-emulator.patch - https://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl
  DEBPKG​:debian/cpan-missing-site-dirs - https://bugs.debian.org/688842 Fix CPAN​::FirstTime defaults with nonexisting site dirs if a parent is writable
  DEBPKG​:fixes/memoize_storable_nstore - [rt.cpan.org #77790] https://bugs.debian.org/587650 Memoize​::Storable​: respect 'nstore' option not respected
  DEBPKG​:debian/regen-skip - Skip a regeneration check in unrelated git repositories
  DEBPKG​:debian/makemaker-pasthru - https://bugs.debian.org/758471 Pass LD settings through to subdirectories
  DEBPKG​:debian/makemaker-manext - https://bugs.debian.org/247370 Make EU​::MakeMaker honour MANnEXT settings in generated manpage headers
  DEBPKG​:debian/kfreebsd-softupdates - https://bugs.debian.org/796798 Work around Debian Bug#796798
  DEBPKG​:fixes/autodie-scope - https://bugs.debian.org/798096 Fix a scoping issue with "no autodie" and the "system" sub
  DEBPKG​:fixes/memoize-pod - [rt.cpan.org #89441] Fix POD errors in Memoize
  DEBPKG​:debian/hurd-softupdates - https://bugs.debian.org/822735 Fix t/op/stat.t failures on hurd
  DEBPKG​:fixes/math_complex_doc_great_circle - https://bugs.debian.org/697567 [rt.cpan.org #114104] Math​::Trig​: clarify definition of great_circle_midpoint
  DEBPKG​:fixes/math_complex_doc_see_also - https://bugs.debian.org/697568 [rt.cpan.org #114105] Math​::Trig​: add missing SEE ALSO
  DEBPKG​:fixes/math_complex_doc_angle_units - https://bugs.debian.org/731505 [rt.cpan.org #114106] Math​::Trig​: document angle units
  DEBPKG​:fixes/cpan_web_link - https://bugs.debian.org/367291 CPAN​: Add link to main CPAN web site
  DEBPKG​:fixes/time_piece_doc - https://bugs.debian.org/817925 Time​::Piece​: Improve documentation for add_months and add_years
  DEBPKG​:fixes/extutils_makemaker_reproducible - https​://bugs.debian.org/835815 https://bugs.debian.org/834190 Make perllocal.pod files reproducible
  DEBPKG​:fixes/file_path_hurd_errno - File-Path​: Fix test failure in Hurd due to hard-coded ENOENT
  DEBPKG​:debian/hppa_op_optimize_workaround - https://bugs.debian.org/838613 Temporarily lower the optimization of op.c on hppa due to gcc-6 problems
  DEBPKG​:debian/installman-utf8 - https://bugs.debian.org/840211 Generate man pages with UTF-8 characters
  DEBPKG​:fixes/file_path_chmod_race - https://bugs.debian.org/863870 [rt.cpan.org #121951] Prevent directory chmod race attack.
  DEBPKG​:fixes/extutils_file_path_compat - Correct the order of tests of chmod(). (#294)
  DEBPKG​:fixes/getopt-long-2 - [rt.cpan.org #120300] Withdraw part of commit 5d9947fb445327c7299d8beb009d609bc70066c0, which tries to implement more GNU getopt_long campatibility. GNU
  DEBPKG​:fixes/getopt-long-3 - provide a default value for optional arguments
  DEBPKG​:fixes/getopt-long-4 - https://bugs.debian.org/864544 [rt.cpan.org #122068] Fix issue #122068.
  DEBPKG​:fixes/fbm-instr-crash - [bb152a4] [perl #131575] don't call Perl_fbm_instr() with negative length
  DEBPKG​:fixes/test-builder-reset - https://bugs.debian.org/865894 Reset inside subtest maintains parent
  DEBPKG​:debian/CVE-2016-1238/base-pm-amends-pt2 - [a77da41] Limit dotless-INC effect on base.pm with guard​:
  DEBPKG​:debian/hppa_opmini_optimize_workaround - https://bugs.debian.org/869122 Lower the optimization level of opmini.c on hppa
  DEBPKG​:debian/sh4_op_optimize_workaround - https://bugs.debian.org/869373 Also lower the optimization level of op.c and opmini.c on sh4
  DEBPKG​:fixes/json-pp-example - [rt.cpan.org #92793] https://bugs.debian.org/871837 fix RT-92793​: bug in SYNOPSIS
  DEBPKG​:debian/customized - Update customized.dat for files patched in Debian
  DEBPKG​:fixes/CVE-2017-12837 - https://bugs.debian.org/875596 [perl #131582] [66288bb] regcomp [perl #131582]
  DEBPKG​:fixes/CVE-2017-12883 - https://bugs.debian.org/875597 [perl #131598] [2692dda] PATCH​: [perl #131598]

---

@​INC for perl 5.26.0​:
  /home/jima/lib/perl
  /home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi
  /home/jima/perl5/lib/perl5/5.26.0/x86_64-linux-gnu-thread-multi
  /home/jima/perl5/lib/perl5/5.26.0
  /home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi
  /home/jima/perl5/lib/perl5
  /etc/perl
  /usr/local/lib/x86_64-linux-gnu/perl/5.26.0
  /usr/local/share/perl/5.26.0
  /usr/lib/x86_64-linux-gnu/perl5/5.26
  /usr/share/perl5
  /usr/lib/x86_64-linux-gnu/perl/5.26
  /usr/share/perl/5.26
  /usr/local/lib/site_perl
  /usr/lib/x86_64-linux-gnu/perl-base

---

Environment for perl 5.26.0​:
  HOME=/home/jima
  LANG=en_US.UTF-8
  LANGUAGE (unset)
  LC_COLLATE=C
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/home/jima/perl5/bin​:/home/jima/bin​:/home/jima/jima_tools/x86_64/bin​:/home/jima/jima_tools/bin​:/usr/bin​:/bin​:/usr/sbin​:/sbin​:/usr/bin/X11​:/usr/local/bin​:/usr/local/sbin​:/usr/games​:/usr/local/games​:/usr/lib/jvm/java-8-oracle/bin​:/usr/lib/jvm/java-8-oracle/db/bin​:/usr/lib/jvm/java-8-oracle/jre/bin​:.
  PERL5LIB=/home/jima/lib/perl​:/home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi​:/home/jima/perl5/lib/perl5
  PERL_BADLANG (unset)
  PERL_LOCAL_LIB_ROOT=/home/jima/perl5
  PERL_MB_OPT=--install_base /home/jima/perl5
  PERL_MM_OPT=INSTALL_BASE=/home/jima/perl5
  SHELL=/bin/bash

[p5pRT]

From @tonycoz

On Wed, Dec 20, 2017 at 01​:55​:45PM -0800, via RT wrote​:

$ perl -we 'local @​SIG{ keys %SIG };'
No such signal​: SIGUNUSED at -e line 1.
No such signal​: SIGUNUSED at -e line 1.

There is an easy work-around, namely localizing only the specific
signals which are about to be temporarily changed (e.g. HUP INT TERM)
(and setting any to undef has, I guess, undefined effects).

However something isn't right if there is a key in %SIG which
can not be used for anything.

Do you see this only with the Debian build of perl, or with a build
from source as well?

I'm wondering if this was introduced by the patch discussed in​:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=875927

The original issue was also discussed at https://rt-archive.perl.org/perl5/Ticket/Display.html?id=132105

Tony

[p5pRT]

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

[p5pRT]

From @ntyni

On Thu, Dec 21, 2017 at 09​:18​:20AM +1100, Tony Cook wrote​:

On Wed, Dec 20, 2017 at 01​:55​:45PM -0800, via RT wrote​:

$ perl -we 'local @​SIG{ keys %SIG };'
No such signal​: SIGUNUSED at -e line 1.
No such signal​: SIGUNUSED at -e line 1.

There is an easy work-around, namely localizing only the specific
signals which are about to be temporarily changed (e.g. HUP INT TERM)
(and setting any to undef has, I guess, undefined effects).

However something isn't right if there is a key in %SIG which
can not be used for anything.

Do you see this only with the Debian build of perl, or with a build
from source as well?

I'm wondering if this was introduced by the patch discussed in​:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=875927

The original issue was also discussed at https://rt-archive.perl.org/perl5/Ticket/Display.html?id=132105

It's clearly related, but the report is about Ubuntu's perl
(5.26.0-8ubuntu1, visible in the 'Locally applied patches list' at
'DEBPKG​:debian/patchlevel').

I think Ubuntu applied an earlier and different fix as a result of

https://bugs.launchpad.net/ubuntu/+source/libanyevent-perl/+bug/1717367

but I can't seem to find a link the actual patch easily...
--
Niko Tyni ntyni@​debian.org

[p5pRT]

From @jimav

The perl comes with Ubuntu 17.10, which I am guessing is the same as
Debian.

I have not tried compiling Perl from source.

On Dec 20, 2017 2​:18 PM, "Tony Cook via RT" <perlbug-followup@​perl.org>
wrote​:

On Wed, Dec 20, 2017 at 01​:55​:45PM -0800, via RT wrote​:

$ perl -we 'local @​SIG{ keys %SIG };'
No such signal​: SIGUNUSED at -e line 1.
No such signal​: SIGUNUSED at -e line 1.

There is an easy work-around, namely localizing only the specific
signals which are about to be temporarily changed (e.g. HUP INT TERM)
(and setting any to undef has, I guess, undefined effects).

However something isn't right if there is a key in %SIG which
can not be used for anything.

Do you see this only with the Debian build of perl, or with a build
from source as well?

I'm wondering if this was introduced by the patch discussed in​:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=875927

The original issue was also discussed at https://rt-archive.perl.org/perl5/Ticket/
Display.html?id=132105

Tony

[p5pRT]

From @ntyni

On Sun, Dec 24, 2017 at 09​:13​:11PM -0800, Jim Avera wrote​:

The perl comes with Ubuntu 17.10, which I am guessing is the same as
Debian.

No, they are not the same.

I managed to find a link for the relevant Ubuntu change​:

http​://deriv.debian.net/patches/p/perl/Debian_perl_5.26.0-8_Ubuntu_perl_5.26.0-8ubuntu1.debian.patch

while the change that went into Debian later is at

https://anonscm.debian.org/cgit/perl/perl.git/commit/?id=c476030a3d41e535e5f5500fe58df21ffd87c242

Both attempt to re-add SIGUNUSED for binary compatibility when building on
glibc >= 2.26. One clear difference between them is that Ubuntu mangles
config.h after running Configure while Debian uses the config.over
mechanism. I haven't investigated whether this makes any difference in
the behaviour of the build result; config.over just felt like a cleaner
solution to me when I implemented the Debian fix.

However, Ubuntu's adding zero to SIG_NUM looks wrong and the probable
cause of this bug to me. SIGUNUSED is 31 (alias for SIGSYS) on at least
all the Debian architectures where it exists in the first place, and
Perl_magic_setsig() gives the warning reported here ('No such signal')
when the signal number is zero or negative.

So I think this can only be fixed in Ubuntu, and presumably somebody
needs to file a Ubuntu bug for that to happen.

Hope this helps,
--
Niko Tyni ntyni@​debian.org

[p5pRT]

From @jimav

On Tue, 26 Dec 2017 11​:17​:27 -0800, ntyni@​debian.org wrote​:

So I think this can only be fixed in Ubuntu, and presumably somebody
needs to file a Ubuntu bug for that to happen.

Done.
https://bugs.launchpad.net/ubuntu/+source/perl/+bug/1740214

[p5pRT]

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