Function slaveMode

app/redis-6.2.6/src/redis-cli.c:7129–7187

}

static void slaveMode(void) {
    static char eofmark[RDB_EOF_MARK_SIZE];
    static char lastbytes[RDB_EOF_MARK_SIZE];
    static int usemark = 0;
    unsigned long long payload = sendSync(context,eofmark);
    char buf[1024];
    int original_output = config.output;

    if (payload == 0) {
        payload = ULLONG_MAX;
        memset(lastbytes,0,RDB_EOF_MARK_SIZE);
        usemark = 1;
        fprintf(stderr,"SYNC with master, discarding "
                       "bytes of bulk transfer until EOF marker...\n");
    } else {
        fprintf(stderr,"SYNC with master, discarding %llu "
                       "bytes of bulk transfer...\n", payload);
    }


    /* Discard the payload. */
    while(payload) {
        ssize_t nread;

        nread = readConn(context,buf,(payload > sizeof(buf)) ? sizeof(buf) : payload);
        if (nread <= 0) {
            fprintf(stderr,"Error reading RDB payload while SYNCing\n");
            exit(1);
        }
        payload -= nread;

        if (usemark) {
            /* Update the last bytes array, and check if it matches our delimiter.*/
            if (nread >= RDB_EOF_MARK_SIZE) {
                memcpy(lastbytes,buf+nread-RDB_EOF_MARK_SIZE,RDB_EOF_MARK_SIZE);
            } else {
                int rem = RDB_EOF_MARK_SIZE-nread;
                memmove(lastbytes,lastbytes+nread,rem);
                memcpy(lastbytes+rem,buf,nread);
            }
            if (memcmp(lastbytes,eofmark,RDB_EOF_MARK_SIZE) == 0)
                break;
        }
    }

    if (usemark) {
        unsigned long long offset = ULLONG_MAX - payload;
        fprintf(stderr,"SYNC done after %llu bytes. Logging commands from master.\n", offset);
        /* put the slave online */
        sleep(1);
        sendReplconf("ACK", "0");
    } else
        fprintf(stderr,"SYNC done. Logging commands from master.\n");

    /* Now we can use hiredis to read the incoming protocol. */
    config.output = OUTPUT_CSV;
    while (cliReadReply(0) == REDIS_OK);
    config.output = original_output;