list.c

#include "list.h"

typedef struct node node_t;
struct node
{
	node_t* next;
	void* data;
};

struct list
{
	node_t* head;
	node_t* back;
	list_value_deleter_t* deleter;
};

// low-level life-time management
static list_t* list_alloc() { return malloc(sizeof(list_t)); }
static void list_free(list_t* list) { free(list); }

static void list_init(list_t* list, list_value_deleter_t* deleter)
{
	list->head = list->back = calloc(1, sizeof(node_t));
	list->deleter = deleter;
}
static void list_deinit(list_t* list) { free(list->head); }

list_t* list_new(list_value_deleter_t* deleter)
{
	list_t* list = list_alloc();
	list_init(list, deleter);
	return list;
}
list_t* list_new_default() { return list_new(&free); }

void list_delete(list_t* list)
{
	list_clear(list);
	list_deinit(list);
	list_free(list);
}

bool list_not_empty(list_t* list) { return list->head->next; }

void list_clear(list_t* list)
{
	while (list_not_empty(list))
		list_pop_front(list);
}

void* list_remove_front(list_t* list)
{
	node_t* front = list->head->next;
	list->head->next = front->next;
	void* data = front->data;
	free(front);
	return data;
}

void list_pop_front(list_t* list)
{
	void* data = list_remove_front(list);
	list->deleter(data);
}

void list_push_back(list_t* list, void* data)
{
	node_t* node = malloc(sizeof(node_t));
	node->next = NULL;
	node->data = data;
	list->back->next = node;
	list->back = node;
}

list.h

#pragma once
#include <stdbool.h>
#include <stdlib.h>

typedef struct list list_t;
typedef void list_value_deleter_t(void*);

list_t* list_new(list_value_deleter_t* deleter);
list_t* list_new_default();
void list_delete(list_t* list);

bool list_not_empty(list_t* list);
void list_clear(list_t* list);

void* list_remove_front(list_t* list);
void list_pop_front(list_t* list);
void list_push_back(list_t* list, void* data);

test.c

#include "list.h"

list_t* int_list_new() { return list_new_default(); }
void int_list_push_back(list_t* list, int x)
{
	int* value = malloc(sizeof(int));
	*value = x;
	list_push_back(list, value);
}

int main()
{
	list_t* list = int_list_new();
	int_list_push_back(list, 1);
	int_list_push_back(list, 2);
	int_list_push_back(list, 3);
}