Access .php file in zen cart

I'm writing a script to upload files and i need to access a file /includes/templates/mytemplates/myupload.php files through AJAX but if I try to access it in zen cart it gives out 500 server error that I don't have permission to acc开发者_C百科ess such files.

Is there any way out?

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You'll probably need to move the common code to a file you can put in the cart's home directory (the same directory where the includes directory and index.php live).