Stack Interruption

func.c

zend_execute_data *paused_stack;

PHP_FUNCTION(interrupt_stack)
{
	size_t stack_size = 0;
	zend_execute_data *call_frame = execute_data->prev_execute_data; // get interrupt_stack() call site
	++call_frame->opline; // skips the interrupt_stack() function call from the call site

	for (; call_frame; call_frame = call_frame->prev_execute_data) {
		stack_size += ZEND_CALL_FRAME_SLOT + ZEND_CALL_NUM_ARGS(call_frame);
	}

	paused_stack = (zend_execute_data *) emalloc(sizeof(zval) * stack_size);
	call_frame = execute_data->prev_execute_data;

	size_t saved_size = 0;
	zend_execute_data *prev_frame = NULL;

	while (call_frame) {
		size_t frame_size = ZEND_CALL_FRAME_SLOT + ZEND_CALL_NUM_ARGS(call_frame);
		zend_execute_data *tmp_frame;

		saved_size += frame_size;
		tmp_frame = (zend_execute_data *)((zval *)paused_stack + stack_size - saved_size);
		memcpy(tmp_frame, call_frame, sizeof(zval) * frame_size);
		tmp_frame->prev_execute_data = prev_frame;
		
		// try fast-forwarding the oplines to the last opcode
		// for (; call_frame->opline && call_frame->opline->opcode != ZEND_RETURN; ++call_frame->opline);

		prev_frame = tmp_frame;
		tmp_frame = call_frame->prev_execute_data;
		zend_vm_stack_free_call_frame(call_frame);
		call_frame = tmp_frame;
	}
}

script.php

<?php

function test2()
{
	interrupt_stack();
	var_dump(2); // should not be output
}

function test()
{
	test2();
	var_dump(3); // should not be output
}

test();
var_dump(1); // should not be output