use strict;
use Data::Dumper;

while (<DATA>)
{
    chomp;
    my @rec;
    foreach (split /"(.*?)(?:(?<!")"(?!")|(?<="")"(?!"))|,/)
        { s/""/"/g, push @rec, $_ if $_ }
    print Dumper(\@rec);
}

__DATA__
1,"Hello, world",This is good,2
121212,"Simpson, Bart",Springfield,"Roger"
121212,"2"" tape, ""white",springfield,"Roger"
121212,"Simpson "", Bart",Springfield,"Roger"
121212,"2""",springfield,"Roger"
[download]

use Text::CSV_XS;
use Data::Dumper;

my $csv = Text::CSV_XS->new();
while (<DATA>)
{
    chomp;
    my $status = $csv->parse($_);
    my @rec = $csv->fields();
    print Dumper(\@rec);
}

__DATA__
1,"Hello, world",This is good,2
121212,"Simpson, Bart",Springfield,"Roger"
121212,"2"" tape, ""white",springfield,"Roger"
121212,"Simpson "", Bart",Springfield,"Roger"
121212,"2""",springfield,"Roger"
[download]