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PHP and ini_set() – A few things you should know

Today I was writing some code for a website I'm building and came across a problem when trying to set the include path. When I was using set_include_path() and ini_set() to set the include_path, both functions would return false. It took me some time and a bit of help from Davey to finally figure out what was going on.

In my Apache configuration I was using php_admin_value to set an include_path for one of my virtual hosts. If you're not familiar with php_admin_value, you can see the manual page here. By using php_admin_value in the httpd.conf (or a vhost), you're there by telling PHP to force that setting and disallow anything else to change it, meaning PHP scripts or even .htaccess files. That was fine, except what I didn't realize, is that for some reason PHP sees that setting and disallows it to be changed in any other virtual host or PHP script running under Apache. I can only speculate that this behavior is a bug and not intended. I would assume for that value to only affect the virtual host it was declared in, but instead, I spent 30 minutes debugging my code wondering why my calls to set_include_path() were returning false.

Let me just clarify for a second, the virtual host I had php_admin_value on was called, lets say foo.example.com and the code I was working on, that was returning false, was in the virtual host for bar.example.com. So, as soon as I realized that was the only place I was using php_admin_value at was foo.example.com, I changed it to php_value and restarted Apache with the new configuration. Instantly the code on bar.example.com began working as expected and setting my new include_path value. I'm not sure if this is default expected behavior, but it's not what I expected at all. I will be filing a bug report to verify this though.

Well, that was my fun for the evening. I just wanted everyone to be aware of the effects php_admin_value and php_admin_flag have on your Apache configuration. If anyone has any different results or findings, please let me know!