STDIN <> and PerlIO doc

[p5pRT]

Migrated from rt.perl.org#105658 (status was 'open')

Searchable as RT105658$

[p5pRT]

From @Greenfactory

Created by @Greenfactory

#!/usr/bin/perl
use strict;
use warnings;

my $data = "aaa\nbbb\nccc\n";

# Ok
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<STDIN>)
{
  print "[[$ARGV]]***$_";
}

# Bug
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<>)
{
  # print PerlIO.pod
  print "[[$ARGV]]***$_";
}

Perl Info

Flags:
    category=core
    severity=low

Site configuration information for perl 5.10.1:

Configured by Debian Project at Fri Apr 22 19:20:15 UTC 2011.

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

  Platform:
    osname=linux, osvers=2.6.24-28-server,
archname=x86_64-linux-gnu-thread-multi
    uname='linux allspice 2.6.24-28-server #1 smp wed aug 18 21:17:51 utc
2010 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.10.1
-Dsitearch=/usr/local/lib/perl/5.10.1 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm
-DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.1
-Dd_dosuid -des'
    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
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.4.5', 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='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.12.1.so, so=so, useshrplib=true,
libperl=libperl.so.5.10.1
    gnulibc_version='2.12.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib
-fstack-protector'

Locally applied patches:
    DEBPKG:debian/arm_thread_stress_timeout -
http://bugs.debian.org/501970Raise the timeout of
ext/threads/shared/t/stress.t to accommodate slower
build hosts
    DEBPKG:debian/cpan_config_path - Set location of CPAN::Config to
/etc/perl as /usr may not be writable.
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS
default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - http://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 - http://bugs.debian.org/290336 Tweak enc2xs
to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno
version check due to upgrade problems with long-running processes.
    DEBPKG:debian/extutils_hacks - Various debian-specific ExtUtils changes
    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/m68k_thread_stress -
http://bugs.debian.org/495826Disable some threads tests on m68k for
now due to missing TLS.
    DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
    DEBPKG:debian/module_build_man_extensions -
http://bugs.debian.org/479460 Adjust Module::Build manual page extensions
for the Debian Perl policy
    DEBPKG:debian/perl_synopsis - http://bugs.debian.org/278323 Rearrange
perl.pod
    DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list
of libraries wanted to what we actually need.
    DEBPKG:debian/use_gdbm - Explicitly link against -lgdbm_compat in
ODBM_File/NDBM_File.
    DEBPKG:fixes/assorted_docs - http://bugs.debian.org/443733 [384f06a]
Math::BigInt::CalcEmu documentation grammar fix
    DEBPKG:fixes/net_smtp_docs - http://bugs.debian.org/100195
[rt.cpan.org#36038] Document the Net::SMTP 'Port' option
    DEBPKG:fixes/processPL - http://bugs.debian.org/357264
[rt.cpan.org#17224] Always use PERLRUNINST when building perl modules.
    DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip
include directories in /usr/local
    DEBPKG:fixes/pod2man-index-backslash -
http://bugs.debian.org/521256Escape backslashes in .IX entries
    DEBPKG:debian/disable-zlib-bundling - Disable zlib bundling in
Compress::Raw::Zlib
    DEBPKG:fixes/kfreebsd_cppsymbols -
http://bugs.debian.org/533098[3b910a0] Add gcc predefined macros to
$Config{cppsymbols} on GNU/kFreeBSD.
    DEBPKG:debian/cpanplus_definstalldirs -
http://bugs.debian.org/533707Configure CPANPLUS to use the site
directories by default.
    DEBPKG:debian/cpanplus_config_path - Save local versions of
CPANPLUS::Config::System into /etc/perl.
    DEBPKG:fixes/kfreebsd-filecopy-pipes -
http://bugs.debian.org/537555[16f708c] Fix File::Copy::copy with pipes
on GNU/kFreeBSD
    DEBPKG:fixes/anon-tmpfile-dir - http://bugs.debian.org/528544 [perl
#66452] Honor TMPDIR when open()ing an anonymous temporary file
    DEBPKG:fixes/abstract-sockets - http://bugs.debian.org/329291 [89904c0]
Add support for Abstract namespace sockets.
    DEBPKG:fixes/hurd_cppsymbols - http://bugs.debian.org/544307 [eeb92b7]
Add gcc predefined macros to $Config{cppsymbols} on GNU/Hurd.
    DEBPKG:fixes/autodie-flock - http://bugs.debian.org/543731 Allow for
flock returning EAGAIN instead of EWOULDBLOCK on linux/parisc
    DEBPKG:fixes/archive-tar-instance-error - http://bugs.debian.org/539355[
rt.cpan.org #48879] Separate Archive::Tar instance error strings from each
other
    DEBPKG:fixes/positive-gpos - http://bugs.debian.org/545234 [perl
#69056] [c584a96] Fix \\G crash on first match
    DEBPKG:debian/devel-ppport-ia64-optim -
http://bugs.debian.org/548943Work around an ICE on ia64
    DEBPKG:fixes/trie-logic-match - http://bugs.debian.org/552291 [perl
#69973] [0abd0d7] Fix a DoS in Unicode processing [CVE-2009-3626]
    DEBPKG:fixes/hppa-thread-eagain - http://bugs.debian.org/554218 make
the threads-shared test suite more robust, fixing failures on hppa
    DEBPKG:fixes/crash-on-undefined-destroy -
http://bugs.debian.org/564074[perl #71952] [1f15e67] Fix a NULL
pointer dereference when looking for a
DESTROY method
    DEBPKG:fixes/tainted-errno - http://bugs.debian.org/574129 [perl
#61976] [be1cf43] fix an errno stringification bug in taint mode
    DEBPKG:patchlevel - http://bugs.debian.org/567489 List packaged patches
for 5.10.1-12 in patchlevel.h


@INC for perl 5.10.1:
    /etc/perl
    /usr/local/lib/perl/5.10.1
    /usr/local/share/perl/5.10.1
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.10
    /usr/share/perl/5.10
    /usr/local/lib/site_perl
    .


Environment for perl 5.10.1:
    HOME=/home/green
    LANG=ru_RU.utf8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=/home/green/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

[p5pRT]

From @cpansprout

On Thu Dec 08 03​:25​:08 2011, evdokimov.denis@​gmail.com wrote​:

#!/usr/bin/perl
use strict;
use warnings;

my $data = "aaa\nbbb\nccc\n";

# Ok
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<STDIN>)
{
print "[[$ARGV]]***$_";
}

# Bug
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<>)
{
# print PerlIO.pod
print "[[$ARGV]]***$_";
}

By closing STDIN you are closing fd 0, which is reused by the next file
opened.

I seem to remember this came up about three years ago and the consensus
was that it is not a bug. I’m not sure.

If my memory serves me correctly, searching for ‘you passed sub
protections’ and ‘This gotta change’ in the archives will bring it up.

--

Father Chrysostomos

[p5pRT]

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

[p5pRT]

From @moonlibs

The problem is not in closing fd 0

Let's look at the following sample​:

# dup.pl
open my $fh, '<&=',0 or die;
print fileno STDIN, "​:", scalar readline STDIN;
close STDIN;
print fileno $fh, "​:", scalar readline $fh;

########
bash $ { echo 1; sleep 1; echo 2; } | perl dup.pl
0​:1
0​:2

(During this I've investigated, that if we do echo -ne "1\n2\n" | perl
dup.pl, then <$fh> receive nothing. I think that's because of buffered
read. Don't know should be this considered a bug)

Then we add the same

open my $fh, '<&=',0 or die;

to the beginning of the example and check the fileno at the end

0 == fileno $fh or die "fileno fh nonzero";

then we will see, that fileno 0 was kept, it still assigned to stdin (this
could be checked additionally), but the behavior of this program still the
same​: we got an output of PerlIO.pm

On Thu, Dec 8, 2011 at 9​:18 PM, Father Chrysostomos via RT <
perlbug-followup@​perl.org> wrote​:

On Thu Dec 08 03​:25​:08 2011, evdokimov.denis@​gmail.com wrote​:

#!/usr/bin/perl
use strict;
use warnings;

my $data = "aaa\nbbb\nccc\n";

# Ok
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<STDIN>)
{
print "[[$ARGV]]***$_";
}

# Bug
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<>)
{
# print PerlIO.pod
print "[[$ARGV]]***$_";
}

By closing STDIN you are closing fd 0, which is reused by the next file
opened.

I seem to remember this came up about three years ago and the consensus
was that it is not a bug. I’m not sure.

If my memory serves me correctly, searching for ‘you passed sub
protections’ and ‘This gotta change’ in the archives will bring it up.

--

Father Chrysostomos

--
Best wishes,
Vladimir V. Perepelitsa aka Mons Anderson
<inthrax@​gmail.com>, <mons@​cpan.org>
http​://github.com/Mons

[p5pRT]

From mons@rambler-co.ru

The problem is not in closing fd 0

Let's look at the following sample​:

# dup.pl
open my $fh, '<&=',0 or die;
print fileno STDIN, "​:", scalar readline STDIN;
close STDIN;
print fileno $fh, "​:", scalar readline $fh;

########
bash $ { echo 1; sleep 1; echo 2; } | perl dup.pl
0​:1
0​:2

(During this I've investigated, that if we do echo -ne "1\n2\n" | perl dup.pl, then <$fh> receive nothing. I think that's because of buffered read. Don't know should be this considered a bug)

Then we add the same

open my $fh, '<&=',0 or die;

to the beginning of the example and check the fileno at the end

0 == fileno $fh or die "fileno fh nonzero";

then we will see, that fileno 0 was kept, it still assigned to stdin (this could be checked additionally), but the behavior of this program still the same​: we got an output of PerlIO.pm

On 08.12.2011, at 21​:18, Father Chrysostomos via RT wrote​:

On Thu Dec 08 03​:25​:08 2011, evdokimov.denis@​gmail.com wrote​:

#!/usr/bin/perl
use strict;
use warnings;

my $data = "aaa\nbbb\nccc\n";

# Ok
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<STDIN>)
{
print "[[$ARGV]]***$_";
}

# Bug
close STDIN or die $!;
open( STDIN, '<', \$data ) or die $!;
@​ARGV = ();
while (<>)
{
# print PerlIO.pod
print "[[$ARGV]]***$_";
}

By closing STDIN you are closing fd 0, which is reused by the next file
opened.

I seem to remember this came up about three years ago and the consensus
was that it is not a bug. I’m not sure.

If my memory serves me correctly, searching for ‘you passed sub
protections’ and ‘This gotta change’ in the archives will bring it up.

--

Father Chrysostomos