#include "std_allocator.h"

#include <stdlib.h>

static void *allocate(size_t size, size_t alignment, void *user_data) {
	(void)user_data;

	// `aligned_alloc(3)` requires that the requested size be a multiple of the requested alignment.
	// this is safe to do, because we ignore `old_size` everywhere else.
	size_t actual_size = (size + alignment - 1) & ~(alignment - 1);

	return aligned_alloc(alignment, actual_size);
}

static void deallocate(void *old_ptr, size_t old_size, void *user_data) {
	(void)old_size;
	(void)user_data;
	free(old_ptr);
}

static void *reallocate(void *old_ptr, size_t old_size, size_t new_size, size_t alignment, void *user_data) {
	(void)old_size;
	(void)alignment;
	(void)user_data;

	// fixme: does `realloc(3)` preserve alignment?
	return realloc(old_ptr, new_size);
}

SandAllocator sand_new_std_allocator() {
	return (SandAllocator) {
		.allocate = allocate,
		.deallocate = deallocate,
		.reallocate = reallocate,
		.user_data = NULL,
	};
}