| Subject: | User defined functions return values cause overflows in a particular range |
| Date: | Fri, 10 Aug 2007 18:39:21 +0200 |
| To: | <bug-DBD-SQLite [...] rt.cpan.org> |
| From: | "Skora, Thomas" <Thomas.Skora [...] secunet.com> |
Hi!
If a user defined function returns a value between 2^31 and 2^31-1 the
value wraps around into a negative one.
Following example:
---------------------------------------------------
#!/usr/bin/perl
use DBI;
sub return_big {
my ($val) = @_;
return 2**$val;
}
if ($ARGV[0] == 2) {
$dbh = DBI->connect("dbi:SQLite2:dbname=foo", "", "", { PrintError =>
0 } );
} elsif ($ARGV[0] == 3) {
$dbh = DBI->connect("dbi:SQLite:dbname=foo", "", "", { PrintError => 0
} );
}
$dbh->func( "bignumber", 1, \&return_big, "create_function" );
for ( $i = 0; $i <= 40; $i++) {
my $result = $dbh->selectrow_arrayref( "SELECT bignumber($i)" );
print "2^$i = ".$$result[0]."\n";
}
---------------------------------------------------
Causes the output:
---------------------------------------------------
2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 = 1024
2^11 = 2048
2^12 = 4096
2^13 = 8192
2^14 = 16384
2^15 = 32768
2^16 = 65536
2^17 = 131072
2^18 = 262144
2^19 = 524288
2^20 = 1048576
2^21 = 2097152
2^22 = 4194304
2^23 = 8388608
2^24 = 16777216
2^25 = 33554432
2^26 = 67108864
2^27 = 134217728
2^28 = 268435456
2^29 = 536870912
2^30 = 1073741824
2^31 = -2147483648 [Here the error occurs]
2^32 = 4294967296
2^33 = 8589934592
2^34 = 17179869184
2^35 = 34359738368
2^36 = 68719476736
2^37 = 137438953472
2^38 = 274877906944
2^39 = 549755813888
2^40 = 1099511627776
---------------------------------------------------
Seen on a Debian 4.0 on an Athlon 64. The same occurs in DBD::SQLite2.
Regards,
Thomas