Hi Simcha,
I tried your suggestion and it does prevent the SID from being inserted
inside the extension, but causes double ?'s and SID's in some cases.
Thanks,
Cameron
On 8/18/08 2:25 AM, "Simcha Younger" <[EMAIL PROTECTED]> wrote:
>
> Hi
>
>
> You did not put a question mark in your character class ([\/\w\.-] and
> instead you put it together with the session id.
> The expression looks for a sequence without which is not followed by the
> next expression --- ?PHPSESSID\=2u0cca.....
> If it would count the last `p` of `.php` then the next expression would
> violate the negative lookahead.
> Instead it stops just before it, after the `.ph` which is the longest
> expression it could find that fulfills your negative lookahead, and then it
> inserts the new sessionid over there.
>
> Try instead
> $buffer =
> preg_replace('/"http\:\/\/www\.domain\.com([\/\w\.\-]*\??)(?!PHPSESSID\=2u0c
> caffoh6jaeapkke35qpp87;?)/',
> '"http://www.domain.com$1?PHPSESSID=t9gksvpdcuobsnqt98qloe6lg4;', $buffer);
>
> (not tested)
>
>
>
> Simcha Younger
>
> -----Original Message-----
> From: Cameron B. Prince [mailto:[EMAIL PROTECTED]
> Sent: Monday, August 18, 2008 12:56 AM
> To: [email protected]
> Subject: [PHP] Negative Look Ahead Regex - Code Mistake or Bug?
>
> Hello,
>
> I¹ve run into a problem with a regex and need help determining if this is my
> mistake or a bug. The regex is for inserting a SID into every link in the
> buffer before it¹s flushed, but only when each link doesn¹t already have a
> SID.
>
> An example of the code is here:
>
> $buffer =
> preg_replace('/"http\:\/\/www\.domain\.com([\/\w\.-]*)(?!\?PHPSESSID\=2u0cca
> ffoh6jaeapkke35qpp87;?)/',
> '"http://www.domain.com$1?PHPSESSID=t9gksvpdcuobsnqt98qloe6lg4;', $buffer);
>
> The code works correctly in most cases except when a SID already exists and
> there is a path after the .com such as:
>
> http://www.domain.com/path1/path2.php?PHPSESSID=2u0ccaffoh6jaeapkke35qpp87;
>
> When this URL is processed by the regex, it becomes:
>
> http://www.domain.com/path1/path2.ph?PHPSESSID=t9gksvpdcuobsnqt98qloe6lg4;p?
> PHPSESSID=2u0ccaffoh6jaeapkke35qpp87;
>
>
> So the problem is the regex not only falsely matches, it's inserting the SID
> in between 2nd and 3rd letters of the extension.
>
> You can see the code in action here:
>
> http://kottmann.com/test.php
>
> The full source for the test code is also available when viewing the source
> of this page.
>
> I've tested this on PHP v5.1.6 and PHP v5.2.6.
>
> TIA,
> Cameron
>
>
>
>
>
>
>
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