linux 获取本机mac地址

/* function to find the local ethernet MAC address */
int GetLocalMacAddr(const char *ifname, unsigned char *mac)
{
    struct ifreq ifr;
    int fd;
    int rv;// return value - error value from df or ioctl call

    /* determine the local MAC address */
    strcpy(ifr.ifr_name, ifname);
    fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
    if (fd < 0)
    {
        rv = fd;
    }
    else
    {
        rv = ioctl(fd, SIOCGIFHWADDR, &ifr);
        if (rv >= 0)            /* worked okay */
        {
            memcpy(mac, ifr.ifr_hwaddr.sa_data, IFHWADDRLEN);
        }
    }

    return rv;
}