How can i check if ini_set will work on the server?

Question

How can i check if server configuration allows me to set an option like:

ini_set('upload_max_filesize', '8M');

in a PHP script? Here is a list of php.ini directives but i can't really figure out how to make a check before tring to change that value.

Answer 1

Check if I'm allowed to use ini_set for some option, how?

ini_set will return the old value on success, and false* on failure. With this knowledge you can write a statement checking if your call went through, like the below.

$result = ini_set ("some_option", "some_value");
$failure = (version_compare(PHP_VERSION, '5.3.0') >= 0) ? false : '';
if ($result === $failure)
   echo "Unable to use ini_set to change 'some_option'!";

(*): Note the return value changed in PHP 5.3.0 from '' (an empty string) to false. So you need to check your current PHP version as well.

---

Another method is to use ini_get_all which will provide you with details regarding every option available, and it's access level.

$all_option_details = ini_get_all ();

/* see the comments in this post regarding PHP_INI_USER vs INI_USER
 * seems like someone writing the relevant PHP documentation fcuked up
 *
 * props to @soulmerge */

if ($all_option_details['upload_max_filesize']['access'] & INI_USER)
   echo "we are allowed to change upload_max_filesize from with ini_set!";

---

I'd like to disable the use of ini_set for some option(s), how?

There are a few methods of making options unchangeable runtime (in a way disabling ini_set), among them are the following two which you can read more about at the provided link.

• PHP: How to change configuration settings

php_admin_value name value

Sets the value of the specified directive. This can not be used in .htaccess files. Any directive type set with php_admin_value can not be overridden by .htaccess or ini_set(). To clear a previously set value use none as the value.

 

php_admin_flag name on|off

Used to set a boolean configuration directive. This can not be used in .htaccess files. Any directive type set with php_admin_flag can not be overridden by .htaccess or ini_set().

---

Example (taken from this documentation)

<IfModule mod_php5.c>
  php_value include_path ".:/usr/local/lib/php"
  php_admin_flag engine on
</IfModule>

<IfModule mod_php4.c>
  php_value include_path ".:/usr/local/lib/php"
  php_admin_flag engine on
</IfModule>