[php-src] Issue #7957: ob content cannot be clean from ob callback when exits/throws

Issue: https://github.com/php/php-src/issues/7957 Comment Author: KapitanOczywisty This is a bit hacky, but works. Callback in ob_start have to return value to prevent output, but we can exploit garbage collector to stop execution after handling callback return. As far I know, there is no other way. Also, probably better would be to use Error and set_exception_handler. https://3v4l.org/ZNr6L ```php <?php function debug($msg){ fwrite(STDOUT, sprintf("[Debug] %s\n", $msg)); } // capture any unexpected output and exit execution ob_start(function($buffer, $phase){ // prevent exit on ob_end_*() if(($phase & PHP_OUTPUT_HANDLER_FINAL) === 0){ $f = new class ($buffer) { public function __construct(private $buffer) {} public function __destruct() { debug('exit call'); exit(); // or // throw new UnexpectedOutputException($this->buffer); } }; } debug(sprintf("callback called, buffer: %s, type: %d", var_export($buffer, true), $phase)); // prevent buffer call return null; }, 1); // do some work on shutdown register_shutdown_function(function() { debug('ob_end_clean'); ob_end_clean(); debug('shutting down'); }); debug('echo x1'); echo 'x1'; debug('echo x2'); echo 'x2'; ```