Closed
Description
Description
With the single-bracket diamond operator (<>, including implicitly via -n or -p), strange warnings appear if the filename list includes fork popens ('-|').
Steps to Reproduce
perl -E '@::ARGV = qw(-| -| -| -| -| -| -| -|); my $x = 0; while (<>) { ++$x; } say $x'
Expected behavior
While it's unlikely anyone expects popens (including forked variety) to be used with simple input, the sample should probably output a line for every process. Other than failures of the relevant fork and pipe calls, there should be no warning messages issued.
Actual results
Warnings similar to the following are issued:
Can't open -|: Success at -e line 1, <> line 1.
Can't open -|: No such file or directory at -e line 1, <> line 1.
The exact number and ordering may be execution-dependent.
From an examination of strace and doio.c, I suspect what is happening is the following:
nextargvcallsdo_open6to do the 2-arg open logic- Per open of "-|",
do_open6does a forked popen. It returns true in the parent and false in the child. - Since
do_open6returned false in the child,nextargvis treating this as a failed open, and issues aninplacewarning, the specific of which is chosen by the result of astatcall, then proceeds to the next ARGV. - Each time this happens in a child forked directly from the toplevel process, errno hasn't been set by anything so it fails because "Success". In all other processes, the failure of the
do_open6that spawned it will have likely set errno to ENOENT, so subsequent cases will report "No such file or directory", sinceerrnois not cleared at any point.
Number 4 at least was confirmed by doing touch -- '-|' and observing that all No such file or directory warnings were replaced with Success.
Workarounds
I do not imagine there is much intentional use of piped opens - especially forks rather than external commands - in argument lists, but if this were a problem it could be worked around by not using <> and processing @ARGV manually. For cases that do not require supporting piped opens from the command-line, the double-diamond variant <<>> is as usual not subject to this issue.
Perl configuration
Summary of my perl5 (revision 5 version 34 subversion 0) configuration:
Platform:
osname=linux
osvers=4.19.0
archname=x86_64-linux-gnu-thread-multi
uname='linux localhost 4.19.0 #1 smp debian 4.19.0 x86_64 gnulinux '
config_args='-Dmksymlinks -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 -ffile-prefix-map=/dummy/build/dir=. -flto=auto -ffat-lto-objects -flto=auto -ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-Bsymbolic-functions -flto=auto -ffat-lto-objects -flto=auto -Wl,-z,relro -Dlddlflags=-shared -Wl,-Bsymbolic-functions -flto=auto -ffat-lto-objects -flto=auto -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.34 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.34 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.34 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.34.0 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.34.0 -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 -Ui_xlocale -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -dEs -Duseshrplib -Dlibperl=libperl.so.5.34.0'
hint=recommended
useposix=true
d_sigaction=define
useithreads=define
usemultiplicity=define
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=n
default_inc_excludes_dot=define
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='12.2.0'
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/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/x86_64-linux-gnu/libc.so.6
so=so
useshrplib=true
libperl=libperl.so.5.34
gnulibc_version='2.36'
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'
Characteristics of this binary (from libperl):
Compile-time options:
HAS_TIMES
MULTIPLICITY
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_IMPLICIT_CONTEXT
PERL_MALLOC_WRAP
PERL_OP_PARENT
PERL_PRESERVE_IVUV
USE_64_BIT_ALL
USE_64_BIT_INT
USE_ITHREADS
USE_LARGE_FILES
USE_LOCALE
USE_LOCALE_COLLATE
USE_LOCALE_CTYPE
USE_LOCALE_NUMERIC
USE_LOCALE_TIME
USE_PERLIO
USE_PERL_ATOF
USE_REENTRANT_API
USE_THREAD_SAFE_LOCALE
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/perlivp - https://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
DEBPKG:debian/squelch-locale-warnings - https://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
DEBPKG:debian/patchlevel - https://bugs.debian.org/567489 List packaged patches for 5.34.0-5ubuntu1.2 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/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/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: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: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:debian/perldoc-pager - https://bugs.debian.org/870340 [rt.cpan.org #120229] Fix perldoc terminal escapes when sensible-pager is less
DEBPKG:debian/prune_libs - https://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
DEBPKG:debian/deprecate-with-apt - https://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules
DEBPKG:debian/disable-stack-check - https://bugs.debian.org/902779 [GH #16607] Disable debugperl stack extension checks for binary compatibility with perl
DEBPKG:debian/perlbug-editor - https://bugs.debian.org/922609 Use "editor" as the default perlbug editor, as per Debian policy
DEBPKG:debian/eu-mm-perl-base - https://bugs.debian.org/962138 Suppress an ExtUtils::MakeMaker warning about our non-default @INC
DEBPKG:fixes/io_socket_ip_ipv6 - Disable getaddrinfo(3) AI_ADDRCONFIG for localhost and IPv4 numeric addresses
DEBPKG:debian/usrmerge-lib64 - https://bugs.debian.org/914128 Configure / libpth.U: Do not adjust glibpth when /usr/lib64 is present.
DEBPKG:debian/usrmerge-realpath - https://bugs.debian.org/914128 Configure / libpth.U: use realpath --no-symlinks on Debian
DEBPKG:debian/configure-regen - https://bugs.debian.org/762638 Regenerate Configure et al. after probe unit changes
DEBPKG:fixes/x32-io-msg-skip - https://bugs.debian.org/922609 Skip io/msg.t on x32 due to broken System V message queues
DEBPKG:fixes/encode-CVE-2021-36770 - mitigate @INC pollution when loading ConfigLocal
DEBPKG:fixes/gdbm-1.20 - https://bugs.debian.org/993514 [GH #18915] Fix GDBM_File to compile with version 1.20 and earlier
DEBPKG:fixes/gcc-braces-1 - [7169efc] https://bugs.debian.org/1009149 skip using gcc brace groups for STMT_START/END
DEBPKG:fixes/gcc-braces-2 - [e08ee3c] https://bugs.debian.org/1009149 Partially Revert "skip using gcc brace groups for STMT_START/END"
DEBPKG:fixes/perl5db-cmd-l - https://bugs.debian.org/1010866 [b7a355b] lib/perl5db.pl: cmd_l() no longer exists.
DEBPKG:disable-libperl-tests -
DEBPKG:CVE-2020-16156-1.patch - [PATCH] bugfix: signature verification type CANNOT_VERIFY was not recognized
DEBPKG:CVE-2020-16156-2.patch - [PATCH] Add two new failure modes based on cpan_path
DEBPKG:CVE-2020-16156-3.patch - [PATCH] use gpg --verify --output ... to disentangle data and signature
DEBPKG:CVE-2020-16156-4.patch - [PATCH] replacing die with mydie in three spots
DEBPKG:CVE-2020-16156-5.patch - [PATCH] disambiguate the call to gpg --output by adding --verify
DEBPKG:CVE-2020-16156-6.patch - [PATCH] s/gpg/$gpg/ in system, add quotes where needed
DEBPKG:CVE-2020-16156-7.patch - [PATCH] s,/dev/null,$devnull,
DEBPKG:CVE-2023-31484.patch - [PATCH] Add verify_SSL=>1 to HTTP::Tiny to verify https server identity
Built under linux
Compiled at May 23 2023 17:18:57
%ENV:
PERL5LIB="/home/aquanight/perl5/lib/perl5"
PERL_LOCAL_LIB_ROOT="/home/aquanight/perl5"
PERL_MB_OPT="--install_base "/home/aquanight/perl5""
PERL_MM_OPT="INSTALL_BASE=/home/aquanight/perl5"
@INC:
/home/aquanight/perl5/lib/perl5/5.34.0/x86_64-linux-gnu-thread-multi
/home/aquanight/perl5/lib/perl5/5.34.0
/home/aquanight/perl5/lib/perl5/x86_64-linux-gnu-thread-multi
/home/aquanight/perl5/lib/perl5
/etc/perl
/usr/local/lib/x86_64-linux-gnu/perl/5.34.0
/usr/local/share/perl/5.34.0
/usr/lib/x86_64-linux-gnu/perl5/5.34
/usr/share/perl5
/usr/lib/x86_64-linux-gnu/perl-base
/usr/lib/x86_64-linux-gnu/perl/5.34
/usr/share/perl/5.34
/usr/local/lib/site_perl
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