Function freebsd2linux_cmsghdr

lib/ff_syscall_wrapper.c:710–767

}

static inline int
freebsd2linux_cmsghdr(struct linux_msghdr *linux_msg, const struct msghdr *freebsd_msg)
{
    struct cmsghdr *freebsd_cmsg = CMSG_FIRSTHDR(freebsd_msg);
    struct linux_cmsghdr *linux_cmsg = LINUX_CMSG_FIRSTHDR(linux_msg);

    while (freebsd_cmsg && linux_cmsg) {
        unsigned char *freebsd_optval = CMSG_DATA(freebsd_cmsg);
        unsigned char *linux_optval = LINUX_CMSG_DATA(linux_cmsg);

        /*
         * The address of linux_cmsg and freebsd_cmsg coincides while recvmsg,
         * but the position of the variable pointer is different,
         * and the assignment must be reversed.
         *
         * Although sizeof(struct linux_msghdr) and sizeof(struct msghdr) have different lengths,
         * but cmsg_data both skip the same 16 bytes，both aligned to 8 bytes.
         */
        linux_cmsg->cmsg_type = freebsd_cmsg->cmsg_type;
        linux_cmsg->cmsg_level = freebsd_cmsg->cmsg_level;
        linux_cmsg->cmsg_len = LINUX_CMSG_LEN(freebsd_cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)));

        /*
         * The freebsd_msg's cmsg_level and cmsg_type has been moddied while recvmsg,
         * must use linux_cmsg to judge and calculate data length.
         * And don't copy other the bytes that used aligned.
         */
        switch (linux_cmsg->cmsg_level) {
            case IPPROTO_IP:
                switch (linux_cmsg->cmsg_type) {
                    case IP_RECVTOS:
                        linux_cmsg->cmsg_type = LINUX_IP_TOS;
                        *linux_optval = *freebsd_optval;
                        break;
                    case IP_RECVTTL:
                        linux_cmsg->cmsg_len = LINUX_CMSG_LEN(sizeof(int));
                        linux_cmsg->cmsg_type = LINUX_IP_TTL;
                        *(int *)linux_optval = *freebsd_optval;
                        break;
                    /*case XXXX:
                        break;*/
                    default:
                        memcpy(linux_optval, freebsd_optval, linux_cmsg->cmsg_len - sizeof(struct linux_cmsghdr));
                        break;
                }

                break;
            default:
                memcpy(linux_optval, freebsd_optval, linux_cmsg->cmsg_len - sizeof(struct linux_cmsghdr));
                break;
        }

        linux_cmsg = LINUX_CMSG_NXTHDR(linux_msg, linux_cmsg);
        freebsd_cmsg = CMSG_NXTHDR(freebsd_msg, freebsd_cmsg);
    }

    return 0;
}