[perl #24818] bug in fh pointers w/perlio on dup()
Stas Bekman
# Please include the string: [perl #24818]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=24818 >
This is a bug report for perl from st...@stason.org,
generated with the help of perlbug 1.34 running under perl v5.8.1.
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[Please enter your report here]
Consider the following short program:
# using Symbol to support older perls
use Symbol;
for (1..2) {
my $dup = Symbol::gensym();
open $dup, "<&DATA" or die "Can't dup DATA: $!";
print "DATA: " . tell(DATA) . "\n";
print "dup : " . tell($dup) . "\n";
#seek $dup, tell(DATA), 0; # rewind to the beginning
<$dup>;
}
__DATA__
foo
bar
w/o perlio we get:
DATA: 309
dup : 309
DATA: 318
dup : 318
the DATA fh pointer is correctly moved along with 'dup'
as per dup(2).
w/ perlio we get:
DATA: 309
dup : 309
DATA: 309
dup : 313
the DATA fh pointer is frozen and doesn't get moved to
the same pointer as the 'dup' fh.
as rgs quoted on irc:
<rgs> that's what my dup(2) manpage says
<rgs> "After successful return of dup or dup2, the old
and new descriptors may be used interchangeably."
and Nicolas has followed up:
<Nicholas> problem (presumably) is that duping by file
number means that the original file handle has buffered
data, while the new one does not. so underlying Unix fh
is not at the same file offset as the return from ftell
might lead you to think
This is observed with any perl 5.8.x
[Please do not change anything below this line]
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---
Flags:
category=core
severity=medium
---
Site configuration information for perl v5.8.1:
Configured by gb at Mon Sep 1 17:25:48 CEST 2003.
Summary of my perl5 (revision 5.0 version 8 subversion 1) configuration:
Platform:
osname=linux, osvers=2.4.18-23mdksmp, archname=i386-linux-thread-multi
uname='linux hp6.mandrakesoft.com 2.4.18-23mdksmp #1 smp fri aug 2
12:31:40 cest 2002 i686 unknown unknown gnulinux '
config_args='-des -Dinc_version_list=5.8.0/i386-linux-thread-multi 5.8.0
5.6.1 5.6.0 -Darchname=i386-linux -Dcc=gcc -Doptimize=-O2 -fomit-frame-pointer
-pipe -march=i586 -mcpu=pentiumpro -Dprefix=/usr -Dvendorprefix=/usr
-Dsiteprefix=/usr -Dman3ext=3pm -Dcf_by=MandrakeSoft -Dmyhostname=localhost
-Dperladmin=root@localhost -Dd_dosuid -Ud_csh -Duseshrplib -Dusethreads'
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 -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
optimize='-O2 -fomit-frame-pointer -pipe -march=i586 -mcpu=pentiumpro ',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.3.1 (Mandrake Linux 9.2 3.3.1-1mdk)',
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 -lndbm -lgdbm -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.2'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic
-Wl,-rpath,/usr/lib/perl5/5.8.1/i386-linux-thread-multi/CORE'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
RC4
---
@INC for perl v5.8.1:
/usr/lib/perl5/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/5.8.1
/usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.1
/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
/usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.1
/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 v5.8.1:
HOME=/home/stas
LANG=en_GB
LANGUAGE=en_GB:en
LC_ADDRESS=en_CA
LC_COLLATE=en_GB
LC_CTYPE=en_GB
LC_IDENTIFICATION=en_CA
LC_MEASUREMENT=en_CA
LC_MESSAGES=en_GB
LC_MONETARY=en_CA
LC_NAME=en_CA
LC_NUMERIC=en_CA
LC_PAPER=en_CA
LC_TELEPHONE=en_CA
LC_TIME=en_GB
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/usr//bin:/bin:/usr/bin:.:/usr/local/bin:/usr/X11R6/bin:/usr/games:/home/stas/bin:/home/stas/bin:/usr/local/bin:/usr/X11R6/bin:/usr/java/j2re1.4.0/bin/
PERLDOC_PAGER=less -R
PERL_BADLANG (unset)
SHELL=/bin/tcsh
__________________________________________________________________
Stas Bekman JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide ---> http://perl.apache.org
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