Add exit function to Zend API

[wojrut-dt]

Hi, https://wiki.php.net/rfc/exit-as-function has impacted one of Dynatrace functionalities. When "exit" was an opcode it wasn't an issue, but now since the opcode is gone We must have a different way of access in order to keep Dynatrace fully compatible with PHP-8.4.x. I think making zend_exit function pointer and adding ZEND_API directive will solve the problem for us and won't break any third-party projects.

[Girgias]

You should use zend_is_unwind_exit(EG(exception)) to check if exit() has been called. This API exist since 8.0.

[dstogov]

I think you don't need this API.
In your extension MINIT (or post_statup callback), you may find zend_function corresponding to "exit" and override its internal handler.
Similar trick is implemented in opcache

php-src/ext/opcache/zend_accelerator_module.c

Line 436 in 2609127

if ((old_function = zend_hash_str_find_ptr(CG(function_table), "file_exists", sizeof("file_exists")-1)) != NULL) {