#define _GNU_SOURCE

#include <errno.h>
#include <netdb.h>
#include <stdlib.h>

struct hostent* gethostbyaddr(const void* a, socklen_t l, int af) {
    static struct hostent* h;
    size_t size = 63;
    struct hostent* res;
    int err;
    do {
        free(h);
        h = malloc(size += size + 1);
        if (!h) {
            h_errno = NO_RECOVERY;
            return 0;
        }
        err = gethostbyaddr_r(a, l, af, h, (void*)(h + 1), size - sizeof *h, &res, &h_errno);
    } while (err == ERANGE);
    return err ? 0 : h;
}