[perl #21362] positioning after binary read

# New Ticket Created by  "Darwin O.V. Alonso" 
# Please include the string:  [perl #21362]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=21362 >



To: perlbug@perl.org
Subject: positioning after binary read
Cc: dalonso@u.washington.edu
Reply-To: dalonso@u.washington.edu
Message-Id: <5.8.0_5230_1046196265@a9>

This is a bug report for perl from dalonso@u.washington.edu,
generated with the help of perlbug 1.34 running under perl v5.8.0.


-----------------------------------------------------------------

Summary:
The perl function, read(), advances to a different (wrong) position under
Perlv5.8.0/RedHat8.0 as compared to Perlv5.6.1/RedHat7.3.
I use an edited screen capture of -d flag output to show the
positions after a read() under 5.8 and 5.6 below:

*** Under Perlv5.8.0 RedHat 8.0 with -d  ***
 DB<1> b 60
 DB<2> c: MDB main::mdbread(./mdinfo:60):
       read( MDB,$rl, 8) or print( STDERR "failed read\n"), return 0;
 DB<2> p tell(MDB): 0
 DB<3> s main::mdbread(./mdinfo:61):
       ( $recsz, $istep ) = unpack("i2", "$rl" );
 DB<3> p tell(MDB): 10

*** Under Perlv5.6.1 RedHat 7.3 with -d ***
 DB<1> b 60
 DB<2> c: MDB main::mdbread(./mdinfo:60):
 read( MDB,$rl, 8) or print( STDERR "failed read\n"), return 0;
 DB<2> p tell(MDB): 0
 DB<3> s main::mdbread(./mdinfo:61):
       ( $recsz, $istep ) = unpack("i2", "$rl" );
 DB<3> p tell(MDB): 8


[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
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
    /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=/users/alonso
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/net/bin:/usr/local/midas/bin:/users/alonso/bin/sequence:/usr/pgi/linux86/bin:/sbin:/users/alonso/bin:/usr/local/chimera/bin:.
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh

• [perl #21362] positioning after binary read by Darwin O.V. Alonso