random number generator in c without using srand or rand

rand_gen.c

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int rand_gen_int()
{
    int ret;
    int fd;
    int number = 0;
    
    fd = open("/dev/urandom", O_RDWR);
    if (fd < 0)
        return -1;
    ret = read(fd, (void *)&number, sizeof(number));
    if (ret < 0) {
        close(fd);
        return -1;
    }
    
    close(fd);
    return number;
}