I'm working on untainting some directory path input and I would like a bit of advice on cleaning up directory paths.

I derived the following code from untainting user login information. I added in comments to show what I think is going on. Please correct me if I'm way off base here. $de is just some random variable name I popped in for testing. :p

My goal is to allow people to drill down in a specific directory tree such as Current_Directory/X/Y/Z but to refuse to allow them to use relative paths to leave the directory tree such as Current_Directory/../../Important_File_Name. So I came up with the following. 

$de =~ s([^a-zA-Z0-9 _/\.-])()g; #strip everything that's not approved
+.
$de =~ tr(./)(./)s; #Look for repeats of the . and / and squash them.
$de =~ m/(\w+.*)$/; #Strip off leading . and / just in case.
$de = $1;

[download]
Is there anything important I'm missing here?

Is it fair to stick a link to my site here?

Thanks for you patience.

In reply to Cleaning up directory paths. by SavannahLion

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