Regex fix for $pagelinkedfrom (xmlrpc.php)

[tenpura]

xmlrpc.php line 1937:

$pagelinkedfrom = preg_replace('#&([^amp\;])#is', '&$1', $pagelinkedfrom);

doesn't seem to work like it was intended.
It should be something like:

$pagelinkedfrom = preg_replace('#amp;#is', '&', $pagelinkedfrom);
$pagelinkedfrom = preg_replace('#&(.)#is', '&$1', $pagelinkedfrom);

[tenpura]

Oops, It should be like:

$pagelinkedfrom = preg_replace('#&#is', '&', $pagelinkedfrom);
$pagelinkedfrom = preg_replace('#&(.)#is', '&$1', $pagelinkedfrom);

[josephscott]

It looks like your first item:

$pagelinkedfrom = preg_replace('#&#is', '&', $pagelinkedfrom);

is already being done on 1810 using str_replace:

$pagelinkedfrom = str_replace('&', '&', $pagelinkedfrom);

Is there a specific example of where the current code doesn't work as expected?

[tenpura]

I found another one to fix. Please see the attachment.

Is there a specific example of where the current code doesn't work as expected?

Yes. The current code contains a misuse of character class (Square brackets).

Example:

$pagelinkedfrom = '&a=1&m=2&p=3&ok=4&';
$pagelinkedfrom = preg_replace('#&([^amp\;])#is', '&$1', $pagelinkedfrom);
echo $pagelinkedfrom; // result is &a=1&m=2&p=3&ok=4&

[ryan]

(In [6127]) Replace faulty regex. Props tenpura. fixes #4820