[lug] Perl and large numbers on (K)ubuntu

[Gary Hodges]

On 09/23/2011 01:49 PM, Gaurav Vaidya wrote:
> Hi there,
>
> On 23 September 2011 11:24, Gary Hodges<Gary.Hodges at noaa.gov>  wrote:
>> I have some Perl code I have used successfully in the past. Â It makes
>> use of the Date::Manip module. Â I pass seconds to it for time
>> calculations. Â Yesterday I tried running it on my Kubuntu 10.04 machine,
>> and it didn't work. Â I noticed a small number, say one day or one year,
>> of seconds worked, but not on the order of 100 years. Â With iterative
>> trials I found the largest number that works. Â 2147483647. Â I did a
>> google search on that number, and it turns out it has its own Wikipedia
>> page<http://en.wikipedia.org/wiki/2147483647>. Â That number is of
>> course the max value for a 32-bit signed integer.
>>
>> I have tested this on another Ubuntu 10.04 install without success. Â The
>> code does work on a Debian lenny machine. Â I've tried a few things such
>> as "use Math::BigInt" and "use bignum", but neither made any difference.
>> Â None of the machines I have run this on are running 64-bit Linux.
>> perl -V doesn't yield anything obvious.
> Hmm, that is strange. A bit of googling didn't show up any reported
> bugs regarding Date::Manip and 32-bit integers. I'd be curious to see
> the 'perl -V' output anyway, the version number of Date::Manip you're
> using, and - ideally - a small program which demonstrates this bug.
>
> If all else fails, try asking your question at StackOverflow, tagged
> 'perl': there's quite a lot of people hanging out there answering
> questions: http://stackoverflow.com/questions/tagged/perl

Thank you for the reply.  Here is a short program that shows what I am 
describing.
----------
#!/usr/bin/perl
use Date::Manip;
my $secs = 2147483647;  # Increment by one to see the error
my $time = &DateCalc("Jan 1, 1900  00:00:00","+ $secs");
print "$secs $time\n";  # $time is in yyyymmddhh:mn:ss format

# My output (second line is w/secs incremented by one):
# 2147483647 1968012003:14:07
# 2147483648 1831121320:45:56
----------

Here is the output of "perl -V".  The Perl install on this machine is 
whatever came with Kubuntu 10.04 LTS, along with any updates that have 
come along.
==========
Summary of my perl5 (revision 5 version 10 subversion 1) configuration:

   Platform:
     osname=linux, osvers=2.6.24-28-server, 
archname=i486-linux-gnu-thread-multi
     uname='linux roseapple 2.6.24-28-server #1 smp wed aug 18 21:17:51 
utc 2010 i686 gnulinux '
     config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN 
-Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr 
-Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local 
-Dsitelib=/usr/local/share/perl/5.10.1 
-Dsitearch=/usr/local/lib/perl/5.10.1 -Dman1dir=/usr/share/man/man1 
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl 
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio 
-Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib 
-Dlibperl=libperl.so.5.10.1 -Dd_dosuid -des'
     hint=recommended, useposix=true, d_sigaction=define
     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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN 
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include 
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
     optimize='-O2 -g',
     cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing 
-pipe -fstack-protector -I/usr/local/include'
     ccversion='', gccversion='4.4.3', 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='cc', ldflags =' -fstack-protector -L/usr/local/lib'
     libpth=/usr/local/lib /lib /usr/lib /usr/lib64
     libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
     perllibs=-ldl -lm -lpthread -lc -lcrypt
     libc=/lib/libc-2.11.1.so, so=so, useshrplib=true, 
libperl=libperl.so.5.10.1
     gnulibc_version='2.11.1'
   Dynamic Linking:
     dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
     cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib 
-fstack-protector'


Characteristics of this binary (from libperl):
   Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
                         PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP USE_ITHREADS
                         USE_LARGE_FILES USE_PERLIO USE_REENTRANT_API
   Built under linux
   Compiled at Apr 22 2011 18:17:20
   @INC:
     /etc/perl
     /usr/local/lib/perl/5.10.1
     /usr/local/share/perl/5.10.1
     /usr/lib/perl5
     /usr/share/perl5
     /usr/lib/perl/5.10
     /usr/share/perl/5.10
     /usr/local/lib/site_perl
     .