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:encoding() returns wrong value on eof #9882

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p5pRT opened this issue Sep 23, 2009 · 6 comments
Open

:encoding() returns wrong value on eof #9882

p5pRT opened this issue Sep 23, 2009 · 6 comments
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@p5pRT
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p5pRT commented Sep 23, 2009

Migrated from rt.perl.org#69332 (status was 'open')

Searchable as RT69332$
@p5pRT
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p5pRT commented Sep 23, 2009

From @ikegami

Created by @ikegami

When using :encoding, read() returns undef at eof rather than zero.

----- BEGIN code -----
#!/usr/bin/perl

use strict;
use warnings;

sub test {
  my ($fh) = @​_;
  my $buf = '';
  for (1..3) {
  my $rv = read($fh, $buf, 1, length($buf));
  if (defined($rv)) {
  print("read = $rv\n");
  } else {
  print("read = undef, \$!=$!\n");
  }
  }
}

{ open(my $fh, '<', \'ab') or die; test($fh); }
{ open(my $fh, '<​:encoding(iso-8859-1)', \'ab') or die; test($fh); }
----- END code -----

----- BEGIN output -----
read = 1
read = 1
read = 0

read = 1
read = 1
read = undef, $!=
----- END output -----

(newline added for readability)

I haven't managed to track down the cause.

Perl Info 

Flags:
    category=library
    severity=low
    module=PerlIO::encoding

Site configuration information for perl 5.10.1:

Configured by SYSTEM at Mon Aug 24 13:48:02 2009.

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

  Platform:
    osname=MSWin32, osvers=5.00, archname=MSWin32-x86-multi-thread
    uname=''
    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='cl', ccflags ='-nologo -GF -W3 -MD -Zi -DNDEBUG -O1 -DWIN32
-D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DUSE_SITECUSTOMIZE
-DPRIVLIB_LAST_IN_INC -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS
-DUSE_PERLIO -DPERL_MSVCRT_READFIX',
    optimize='-MD -Zi -DNDEBUG -O1',
    cppflags='-DWIN32'
    ccversion='12.00.8804', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='link', ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf
-libpath:"C:\progs\perl5101\lib\CORE"  -machine:x86'
    libpth=\lib
    libs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib
uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib
msvcrt.lib
    perllibs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib
uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib
msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl510.lib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug
-opt:ref,icf  -libpath:"C:\progs\perl5101\lib\CORE"  -machine:x86'

Locally applied patches:
    ACTIVEPERL_LOCAL_PATCHES_ENTRY
    32728 64-bit fix for Time::Local


@INC for perl 5.10.1:
    c:/Progs/perl5101/site/lib
    c:/Progs/perl5101/lib
    .


Environment for perl 5.10.1:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=c:\bin;c:\progs\perl5101\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\WBEM
    PERL_BADLANG (unset)
    SHELL (unset)

@p5pRT
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p5pRT commented Oct 10, 2009

From @obra

Replicated on 5.10.0, vanilla 5.10.1 and 5.11.0

@p5pRT
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p5pRT commented Oct 10, 2009

@obra - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Oct 10, 2009

From @obra

On Sat Oct 10 12​:33​:53 2009, jesse wrote​:

Replicated on 5.10.0, vanilla 5.10.1 and 5.11.0

Also, 5.8.8

@p5pRT
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p5pRT commented Oct 10, 2009

From @obra

When using :encoding, read() returns undef at eof rather than zero.

Thanks very much for your report, Eric. As it turns out, this is a somewhat
longstanding bug and pertains to all PerlIO layers, not just :encoding().

I've added a TODO test based on your report to blead as of commit 86cb0d3.

Best,
Jesse

@p5pRT
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p5pRT commented Oct 10, 2009

From @obra

16​:21 <@​Nicholas> also, as to PerIO behaviour
16​:21 <@​Nicholas> I think that the answer is "whatever 5.005 does without
  PerlIO is more likely to be the 'right' answer"

@xenu xenu removed the Severity Low label Dec 29, 2021
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