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SEEK_END does NOT work - Argument "SEEK_END" isn't numeric in seek at ./bug.p line 20 #21831

Closed JEDtoo closed 10 months ago

JEDtoo commented 10 months ago

Description Can't use SEEK_END because it "isn't numeric" Ubuntu 22.04.3 LTS

In addition, "contributing" and "guidelines" linked here seem to be empty.

Steps to Reproduce

Just try this short program.

#!/usr/bin/perl

# monitor new lines as they are added to the log file
# (real program looks for specific lines)

use strict;
no strict "subs"; #  no seek without this, for some reason
use warnings;

#  Configuration settings.
#       note: all files need full path
my $logfile = "/var/log/syslog";
my $log_wait_interval = 10;
my $inputh;

# Opening a file and reading content
if(open($inputh, '<', $logfile))
{
  print `date +"%d %B %Y"`; # use Un*x date functiona
  seek $inputh, 0, SEEK_END;    # fails
  seek $inputh, 0, 2;           # means SEEK_END, works so program works
  while (1)
  {
    while(<$inputh>)
    {
        my $addr=$_;
        print $addr;
      }
      print "Waiting...\n"; # for someone to add to file
      sleep $log_wait_interval;
    } # wait until there is more in the file with while(1) above

# Executes if file not found
} else {
  warn "Couldn't Open a file $logfile";
  }

Expected behavior It should not issue error message and should work with SEEK_END, as all the documentation says. It took a LONG time to find that 2 means the same

thing.

Perl configuration

jed@mail2024:~/bin$ perl -V
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='11.4.0'
    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='2.35'
  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 5.34.0-3ubuntu1.3 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: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
    DEBPKG:CVE-2023-47038.patch - [PATCH 1/2] Fix read/write past buffer end: perl-security#140
    DEBPKG:CVE-2022-48522.patch - [PATCH] Don't try to Sv[PI]V() on an undef index SV in find_uninit_var()
  Built under linux
  Compiled at Nov 23 2023 14:56:46
  @INC:
    /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
xenu commented 10 months ago

Perldoc says:

For WHENCE you may use the constants SEEK_SET, SEEK_CUR, and SEEK_END (start of the file, current position, end of the file) from the Fcntl module.

So those constants have to be imported from the Fcntl module, e.g. like this: use Fcntl ':seek'.

no strict allows the code to compile because it causes the non-existent constant to be treated as a bareword. This is obviously not the right solution.

Also, Stack Overflow, Perl Monks and the #perl IRC channel on libera.chat are better places for basic Perl questions.