error when changing ereg_replace to preg_replace - php

Question

I am working on old sites and updating the deprecated php functions. I have the following code, which creates an error when I change the ereg to preg.
private function stripScriptTags($string) {
$pattern = array("'\/\*.*\*\/'si", "'<\?.*?\?>'si", "'<%.*?%>'si", "'<script[^>]*?>.*?</script>'si");
$replace = array("", "", "", "");
return ereg_replace($pattern, $replace, $string);
}
This is the error I get:
Fatal error: Allowed memory size of 10000000 bytes exhausted (tried to allocate 6249373 bytes) in C:\Inetpub\qcppos.com\library\vSearch.php on line 403
Is there something else in that line of code that I need to be changing along with the ereg_replace?

Answer 1

So your regexes are as follows:
"'\/\*.*\*\/'si"
"'<\?.*?\?>'si"
"'<%.*?%>'si"
"'<script[^>]*?>.*?</script>'si"
Taking those one at a time, you are first greedily stripping out multiline comments. This is almost certainly where your memory problem is coming from, you should ungreedify that quantifier.
Next up, you are stipping out anything that looks like a PHP tag. This is done with a lazy quantifier, so I don't see any issue with it. Same goes for the ASP tag, and finally the script tag.
Leaving aside potental XSS threats left out by your regex, the main issue seems to be coming from your first regex. Try "'\/\*.*?\*\/'si" instead.

Answer 2

get your memory limitations value
ini_get('memory_limit');
and check your script with memory_get_usage() and memory_get_peak_usage()
(this one needs php 5.2 or higher)
if this turns out to be too low then you can set it higher with:
ini_set("memory_limit","128M"); // "8M" before PHP 5.2.0, "16M" in PHP 5.2.0, > "128M"
Just put in whatever memory you have and works for your script. Keep in mind that this limits the individual php process; to set it globally you need to adapt your php.ini file.
Obviously if it needs an insane amount to run, then consider it a monkeypatch and start rewriting it for better memory footprint.
for more info look at core php.ini directives, search for Resource Limits

Answer 3

Since allowing higher memory allocation wasn't working, the following functions were updated as follows (due to the fact that they aren't actually doing anything but causing issues):
private function stripScriptTags($string)
{
/* $pattern = array("'\/\*.*\*\/'si", "'<\?.*?\?>'si", "'<%.*?%>'si",
"'<script[^>]*?>.*?</script>'si");
$replace = array("", "", "", "");
return ereg_replace($pattern, $replace, $string);
*/
return $string;
}
private function clearSpaces($string, $clear_enters = true)
{
/*$pattern = ($clear_enters == true) ? ("/\s+/") : ("/[ \t]+/");
return preg_replace($pattern, " ", trim($string));
*/
return $string;
}