Using tell(DATA) within __DATA__ file buffer is broken on Win32

Cc: [email protected]
Subject: Using tell(DATA) within __DATA__ file buffer is broken on Win32
Message-Id: <[email protected]>
Reply-To: [email protected]
To: [email protected]


This is a bug report for perl from [email protected],
generated with the help of perlbug 1.39 running under perl 5.12.0.


-----------------------------------------------------------------
[Please describe your issue here]

When I use <DATA> to read part of the DATA file and then "tell DATA", the value returned by "tell DATA" is off by the number of newlines that
have been read.

This has been discussed at perlmonks and another experienced programmer agreed that it is likely a bug. I tested it on Knoppix Linux and it does not happen there.
Another user checked it on ActivePerl 5.12.1 with the code below and it occurred there also.

Thanks,
Brent Shields



http://www.perlmonks.com/?node_id=892784

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

my @data_positions = tell(DATA);
while (<DATA>){
    if (/^__DATA__$/) {
        push @data_positions, tell(DATA);
    }
}

my @fh_positions;
open(my $fh, '<', $0) or die;
while (<$fh>){
    if (/^__DATA__$/) {
        push @fh_positions, tell($fh);
    }
}

print("@data_positions\n");
print("@fh_positions\n");

__DATA__
ab
__DATA__
ab

__DATA__
ab
__DATA__
lotsa junk
nothing


*****************************************************
Output:
389 401 414 426
389 403 419 433





[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.12.0:

Configured by 1 at Thu May  6 16:22:52 2010.

Summary of my perl5 (revision 5 version 12 subversion 0) configuration:
   
  Platform:
    osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
    uname='Win32 strawberryperl 5.12.0.1 #1 Thu May  6 16:09:27 2010 i386'
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags =' -s -O2 -DWIN32 -DHAVE_DES_FCRYPT  -DUSE_SITECUSTOMIZE -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fno-strict-aliasing -mms-bitfields -DPERL_MSVCRT_READFIX',
    optimize='-s -O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='4.4.3', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='long long', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags ='-s -L"C:\strawberry\perl\lib\CORE" -L"C:\strawberry\c\lib"'
    libpth=C:\strawberry\c\lib C:\strawberry\c\i686-w64-mingw32\lib
    libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=, so=dll, useshrplib=true, libperl=libperl512.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -s -L"C:\strawberry\perl\lib\CORE" -L"C:\strawberry\c\lib"'

Locally applied patches:
    

---
@INC for perl 5.12.0:
    C:/strawberry/perl/site/lib
    C:/strawberry/perl/vendor/lib
    C:/strawberry/perl/lib
    .

---
Environment for perl 5.12.0:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=C:\WINNT;C:\WINNT\system32;C:\WINNT\System32\Wbem;C:\Program Files\Intel\DMIX;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Ulead Systems\MPEG;C:\Program Files\ThinkPad\ConnectUtilities;C:\Program Files\Common Files\Lenovo;C:\SQLLIB\BIN;C:\SQLLIB\FUNCTION;C:\Program Files\Utimaco\SafeGuard Easy\;C:\strawberry\c\bin;C:\strawberry\perl\site\bin;C:\strawberry\perl\bin;C:\Program Files\VanDyke Software\SecureFX\;C:\Program Files\GnuWin32\bin\;c:\b\;c:\usr\bin\;C:\Eterra\e_terrabrowser\
    PERL_BADLANG (unset)
    SHELL (unset)