Handle fatal errors in PHP using register_shutdown_function()

Question

According to the comment on this answer it is possible to catch Fatal Errors through a shutdown function which cannot be caught using set_error_handler().

However, I couldn't find out how to determine if the shutdown has occured due to a fatal error or due to the script reaching its end.

Additionally, the debug backtrace functions seem to be defunct in the shutdown function, making it pretty worthless for logging the stack trace where the Fatal Error occured.

So my question is: what's the best way to react on Fatal Errors (especially undefined function calls) while keeping the ability to create a proper backtrace?

Answer 1

This works for me:

function shutdown() {
    $error = error_get_last();
    if ($error['type'] === E_ERROR) {
        // fatal error has occured
    }
}

register_shutdown_function('shutdown');

spl_autoload_register('foo'); 
// throws a LogicException which is not caught, so triggers a E_ERROR

However, you probably know it already, but just to make sure: you can't recover from a E_ERROR in any way.

As for the backtrace, you can't... :( In most cases of a fatal error, especially Undefined function errors, you don't really need it. Pinpointing the file/line where it occured is enough. The backtrace is irrelevant in that case.