303_advanced.c File Reference

Tests advanced reverse trampoline (callback) patterns. More...

#include "common/double_tap.h"
#include "types.h"
#include <infix/infix.h>
#include <string.h>

Include dependency graph for 303_advanced.c:

Macros
#define	DBLTAP_IMPLEMENTATION

Typedefs
typedef int(*	int_func_int) (int)
	A harness that receives the provider, calls it to get the real callback, and then calls that.
typedef int_func_int(*	callback_provider) (void)

Functions
void	pointer_modify_handler (int *p)
	Handler that dereferences a pointer and writes a new value.
void	execute_pointer_modify_callback (void(*func_ptr)(int *), int *p)
	Harness that calls the provided function pointer, passing it an address.
void	inner_callback_handler (int val)
	The inner callback that will be passed as an argument.
void	execute_callback_as_arg_harness (void(*cb)(int))
	The harness function that accepts a function pointer as its argument.
int	final_multiply_handler (int val)
	The innermost handler that will be returned and ultimately called.
void	closure_provider_handler (infix_context_t *context, void *ret, void **args)
	A generic handler for the "provider" closure.
int	call_returned_callback_harness (callback_provider provider, int val)
	subtest ("Callback modifies data via pointer")
	subtest ("Callback passed as an argument")
	subtest ("Closure returns a function pointer (via user_data)")

Variables
	TEST

Detailed Description

Tests advanced reverse trampoline (callback) patterns.

Copyright (c) 2025 Sanko Robinson

This source code is dual-licensed under the Artistic License 2.0 or the MIT License. You may choose to use this code under the terms of either license.

SPDX-License-Identifier: (Artistic-2.0 OR MIT)

The documentation blocks within this file are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

SPDX-License-Identifier: CC-BY-4.0

This test suite verifies the library's ability to handle complex, higher-order function patterns involving callbacks. It consolidates several previous tests to create a focused suite for advanced use cases.

The scenarios tested are:

1. Pointer Modification: A callback receives a pointer to a variable in the caller's scope and modifies its value, a common pattern for "out" parameters.
2. Callback as an Argument: A generated callback (reverse trampoline) is passed as a function pointer argument to a different function (called via a forward trampoline). This tests the interplay between the two FFI mechanisms.
3. Closure Returning a Function Pointer: A closure is generated whose sole purpose is to return a different, dynamically-generated function pointer. This is achieved by storing the target function pointer in the user_data field of the reverse trampoline context, demonstrating a powerful feature for creating stateful, dynamic callback providers.

Macro Definition Documentation

DBLTAP_IMPLEMENTATION

#define DBLTAP_IMPLEMENTATION

Typedef Documentation

callback_provider

typedef int_func_int(* callback_provider) (void)

int_func_int

typedef int(* int_func_int) (int)

A harness that receives the provider, calls it to get the real callback, and then calls that.

Function Documentation

call_returned_callback_harness()

int call_returned_callback_harness	(	callback_provider	provider,
		int	val
	)

closure_provider_handler()

void closure_provider_handler	(	infix_context_t *	context,
		void *	ret,
		void **	args
	)

A generic handler for the "provider" closure.

This handler leverages user_data to return another function pointer. It retrieves the function pointer from its context and writes it to the return buffer.

execute_callback_as_arg_harness()

void execute_callback_as_arg_harness

(

void(*)(int)

cb

)

The harness function that accepts a function pointer as its argument.

execute_pointer_modify_callback()

void execute_pointer_modify_callback	(	void(*)(int *)	func_ptr,
		int *	p
	)

Harness that calls the provided function pointer, passing it an address.

final_multiply_handler()

int final_multiply_handler

(

int

val

)

The innermost handler that will be returned and ultimately called.

inner_callback_handler()

void inner_callback_handler

(

int

val

)

The inner callback that will be passed as an argument.

pointer_modify_handler()

void pointer_modify_handler

(

int *

p

)

Handler that dereferences a pointer and writes a new value.

subtest() [1/3]

subtest

(

"Callback modifies data via pointer"

)

subtest() [2/3]

subtest

(

"Callback passed as an argument"

)

subtest() [3/3]

subtest

(

"Closure returns a function pointer (via user_data)"

)

Variable Documentation

TEST

TEST

Initial value:

{
    plan(3)