SPUG: passing in a reg exp as a string, then interpolating

[ced at carios2.ca.boeing.com]

> does anyone know how to pass a regular expression into a script (in my
> case, from an HTML form) and then evaluate the expression?

> I am passing in a reg exp (like "/^hello/ ")as a string and grabbing it
> (my $regexp = /^hello/ ), and then trying to interpolate:

> push @results, $k if do{ $k =~ @{[ $regexp ]};

> Doesn't seem to be working. Any tricks for doing this?

(The @{[]}  is a mistake and is a severe security  problem if you're 
 pulling the regex in from the command line. Check the CGI books or 
 faqs for details about laundering tainted data) 

The easiest approach would be to pass in the regex without the 
delimiters, e.g., just '^hello', instead of /^hello/. 

Just as a guess you might want something like:

use CGI qw(:standard);
use CGI::Carp qw/fatalsToBrowser/;

...


# launder the user input for dangerous characters, e.g.,
my $regex = param('regex'); 
$regex =~ tr/'"\t\n\r\/<>|;//d; 

# see if there's a match
my $match;
my $k = "foo bar....";

eval { $match = $k =~ /$regex/ };
if ( $@ ) {
   die "regular expression error: $@";
} else {
   push @results, $k if $match;
}


Rgds,
--
Charles DeRykus

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