Chapter 59. Initialization File Support

PHP 4 features a redesigned initialization file support. It's now possible to specify default initialization entries directly in your code, read and change these values at runtime, and create message handlers for change notifications.

To create an .ini section in your own module, use the macros PHP_INI_BEGIN() to mark the beginning of such a section and PHP_INI_END() to mark its end. In between you can use PHP_INI_ENTRY() to create entries.

PHP_INI_BEGIN()
PHP_INI_ENTRY("first_ini_entry",  "has_string_value", PHP_INI_ALL, NULL)
PHP_INI_ENTRY("second_ini_entry", "2",                PHP_INI_SYSTEM, OnChangeSecond)
PHP_INI_ENTRY("third_ini_entry",  "xyz",              PHP_INI_USER, NULL)
PHP_INI_END()

The permissions are grouped into three sections:PHP_INI_SYSTEM allows a change only directly in the php.ini file; PHP_INI_USER allows a change to be overridden by a user at runtime using additional configuration files, such as .htaccess; and PHP_INI_ALL allows changes to be made without restrictions. There's also a fourth level, PHP_INI_PERDIR, for which we couldn't verify its behavior yet.

The fourth parameter consists of a pointer to a change-notification handler. Whenever one of these initialization entries is changed, this handler is called. Such a handler can be declared using the PHP_INI_MH macro:

PHP_INI_MH(OnChangeSecond);             // handler for ini-entry "second_ini_entry"

// specify ini-entries here

PHP_INI_MH(OnChangeSecond)
{

    zend_printf("Message caught, our ini entry has been changed to %s<br>", new_value);

    return(SUCCESS);

}

#define PHP_INI_MH(name) int name(php_ini_entry *entry, char *new_value,
                                  uint new_value_length, void *mh_arg1,
                                  void *mh_arg2, void *mh_arg3)

The change-notification handlers should be used to cache initialization entries locally for faster access or to perform certain tasks that are required if a value changes. For example, if a constant connection to a certain host is required by a module and someone changes the hostname, automatically terminate the old connection and attempt a new one.

Access to initialization entries can also be handled with the macros shown in Table 59-1.

Finally, you have to introduce your initialization entries to PHP. This can be done in the module startup and shutdown functions, using the macros REGISTER_INI_ENTRIES() and UNREGISTER_INI_ENTRIES():

ZEND_MINIT_FUNCTION(mymodule)
{

    REGISTER_INI_ENTRIES();

}

ZEND_MSHUTDOWN_FUNCTION(mymodule)
{

    UNREGISTER_INI_ENTRIES();

}