fxlibc/src/stdlib/calloc.c

#include <stdlib.h>
#include <string.h>

void *calloc(size_t nmemb, size_t size)
{
	unsigned int total_size;

	if(__builtin_umul_overflow(nmemb, size, &total_size))
		return NULL;

	void *mem = malloc(total_size);
	if(mem) memset(mem, 0, total_size);
	return mem;
}