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Re: One true regexp for untainting windows filenames?

by cdarke (Prior)
on Jan 08, 2009 at 08:47 UTC ( #734842=note: print w/ replies, xml ) Need Help??


in reply to One true regexp for untainting windows filenames?

Strictly speaking it is the filesystem which defines which characters are legal, not the operating system. This means that a drive shared between *nix and Windows (using, say, Samba) can have an interesting effect on file naming. Also remember that NTFS filenames can contain Unicode characters.

Take a look at the .pm for File::Basename (which should be in your base release).


Comment on Re: One true regexp for untainting windows filenames?
Re^2: One true regexp for untainting windows filenames?
by jaldhar (Vicar) on Jan 08, 2009 at 23:42 UTC

    Thanks for the tip. I found slightly more understandable code in File::Spec which has resulted in the following regexps: for Unix...

    qr{(\A (?: .* / (?: \.\.?\z )? )? [^/]* )}msx;
    ...and Windows (includes UNC paths)...
    qr{(\A (?: [a-zA-Z]: | (?:\\\\\\\\|//)[^\\\\/]+[\\\\/][^\\\\/]+ )? (?:.*[\\/](?:\.\.?\Z(?!\n))?)? .* )}msx;

    --
    જલધર

      There is no a string that

      qr{(\A (?: .* / (?: \.\.?\z )? )? [^/]* )}msx

      won't match.

      It's wrong for two reasons.

      • "foo" gets "untainted" as "".
      • "x/xx\0xx"" is believed to be a valid file name, but it isn't.

      Valid unix paths and only valid unix paths match

      qr{^([\0]+)\z}

      (Although that doesn't mean there can ever be a file referenced by that path.)

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