Eval is great for getting perl to tell you if something is technically legal or not. But I have a concern.

The task is a little more complex than that. You will have to prevent the (?{code}) construct from finding its way into your user's input, lest they manage to inject some unsavory tidbit into your system. That's just the start. Will your users have the ability to input RE's that are expressed in /x terms? (In other words, where whitespace is not relevant.) They could always use (?x:.....), or any of the other legal options to sort of control the RE's destiny, possibly in a way that you weren't intending. I think that the greater task is not in validating the RE's viability, so much as evaluating its security risk.

As for validating its viability, eval isn't such a bad tool. You would be able to let perl tell you if there's a problem. But perl cannot know if there's a security breech.

I don't know all the possible risks that you should test for. But at minimum disallowing code blocks would be a start.


Dave

In reply to Re: Validating Regular Expression by davido
in thread Validating Regular Expression by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.