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perl 5.8.0 non-blocking PerlIO issue #6062

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p5pRT opened this issue Nov 7, 2002 · 6 comments
Closed

perl 5.8.0 non-blocking PerlIO issue #6062

p5pRT opened this issue Nov 7, 2002 · 6 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Nov 7, 2002

Migrated from rt.perl.org#18265 (status was 'resolved')

Searchable as RT18265$
@p5pRT
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p5pRT commented Nov 7, 2002

From cturner@redhat.com

Created by cturner@redhat.com

The following script functions inappropriately when PERLIO=perlio is
set, but correctly when PERLIO=stdio is set. It seems that, for
nonblocking descriptors, read() can return undef without setting errno
(which should be set to EAGAIN). This bug originated from the
dvd​::rip people, who filed it in our Bugzilla against 5.8.0 in RHL 8.0
(url below). A quick look through bleedperl doesn't show anything
that would fix this, but I've not tested bleedperl itself.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=75264

use strict;
use POSIX qw(​:errno_h mkfifo);
use Fcntl;

# to test this, run 'mkfifo test-fifo' and then 'cat > test-fifo' in a
# different terminal. the open() call will block until a writer to
# the fifo exists.

open FH, "< test-fifo"
  or die "open​: $!";

print "FIFO opened.\n";

my $flags = 0;
fcntl(FH, F_GETFL, $flags)
  or die "Can't get flags​: $!\n";
$flags |= O_NONBLOCK;
fcntl(FH, F_SETFL, $flags)
  or die "Can't set flags​: $!\n";

while (1) {
  my $data;
  my $nread = read FH, $data, 64;
  if (defined $nread) {
  print "Received data $data";
  }
  else {
  print "read returned undefined, errno $!\n";
  if ($! != EAGAIN) {
  print "read​: $!\n";
  last;
  }
  }
}

Perl Info 

Flags:
    category=core
    severity=high

Site configuration information for perl v5.8.0:

Configured by bhcompile at Sun Sep  1 23:55:07 EDT 2002.

Summary of my perl5 (revision 5.0 version 8 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.4.18-11smp, archname=i386-linux-thread-multi
    uname='linux daffy.perf.redhat.com 2.4.18-11smp #1 smp thu aug 15 06:41:59 edt 2002 i686 i686 i386 gnulinux '
    config_args='-des -Doptimize=-O2 -march=i386 -mcpu=i686 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=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 ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -march=i386 -mcpu=i686',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/usr/include/gdbm'
    ccversion='', gccversion='3.2 20020822 (Red Hat Linux Rawhide 3.2-5)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lgdbm -ldb -ldl -lm -lpthread -lc -lcrypt -lutil
    perllibs=-lnsl -ldl -lm -lpthread -lc -lcrypt -lutil
    libc=/lib/libc-2.2.92.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.2.92'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/usr/lib/perl5/5.8.0/i386-linux-thread-multi/CORE'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    


@INC for perl v5.8.0:
    /usr/lib/perl5/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/5.8.0
    /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl/5.6.1
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl
    .


Environment for perl v5.8.0:
    HOME=/home/devel/cturner
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/opt/oracle/bin:/opt/oracle/bin:/usr/kerberos/bin:/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/home/devel/cturner/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Jan 12, 2003

nick@ing-simmons.net - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Jan 12, 2003

From nick@ing-simmons.net

I can reproduce the problem.
Root cause is :perlio just not considering non-blocking IO at all.
So EAGAIN is just annother error condition and causes an EOF.

Requires some thought.

@p5pRT
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p5pRT commented May 18, 2003

From nick@ing-simmons.net

Fixed by change 19556.
(Patch attached)

@p5pRT
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p5pRT commented May 18, 2003

From nick@ing-simmons.net

patch

@p5pRT
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p5pRT commented May 18, 2003

nick@ing-simmons.net - Status changed from 'open' to 'resolved'

@p5pRT p5pRT closed this as completed May 18, 2003
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