文章讲得很清楚 看一下兼容老版本的逻辑

c
    /* Select the corresponding verification method according to the input file type. */
    input_file_type type = getInputFileType(filepath);
    switch (type) {
    case AOF_MULTI_PART:
        checkMultiPartAof(dirpath, filepath, fix); //新版本
        break;
    case AOF_RESP:
        checkOldStyleAof(filepath, fix, 0); //老版本
        break;
    case AOF_RDB_PREAMBLE:
        checkOldStyleAof(filepath, fix, 1)// 老版本
        break;
    }
    
//****************************************************************************************
/* Check if Multi Part AOF is valid. It will check the BASE file and INCR files 
 * at once according to the manifest instructions (this is somewhat similar to 
 * redis' AOF loading).
 * 
 * When the verification is successful, we can guarantee:
 * 1. The manifest file format is valid
 * 2. Both BASE AOF and INCR AOFs format are valid
 * 3. No BASE or INCR AOFs files are missing
 * 
 * Note that in Multi Part AOF, we only allow truncation for the last AOF file.
 * */
void checkMultiPartAof(char *dirpath, char *manifest_filepath, int fix) {
    int total_num = 0, aof_num = 0, last_file;
    int ret;

    printf("Start checking Multi Part AOF\n");
    aofManifest *am = aofLoadManifestFromFile(manifest_filepath);

    if (am->base_aof_info) total_num++;
    if (am->incr_aof_list) total_num += listLength(am->incr_aof_list);

    if (am->base_aof_info) {
        sds aof_filename = am->base_aof_info->file_name;
        sds aof_filepath = makePath(dirpath, aof_filename);
        last_file = ++aof_num == total_num;
        int aof_preable = fileIsRDB(aof_filepath);

        printf("Start to check BASE AOF (%s format).\n", aof_preable ? "RDB":"RESP");
        ret = checkSingleAof(aof_filename, aof_filepath, last_file, fix, aof_preable);
        printAofStyle(ret, aof_filename, (char *)"BASE AOF");
        sdsfree(aof_filepath);
    }

    if (listLength(am->incr_aof_list)) {
        listNode *ln;
        listIter li;

        printf("Start to check INCR files.\n");
        listRewind(am->incr_aof_list, &li);
        while ((ln = listNext(&li)) != NULL) {
            aofInfo *ai = (aofInfo*)ln->value;
            sds aof_filename = (char*)ai->file_name;
            sds aof_filepath = makePath(dirpath, aof_filename);
            last_file = ++aof_num == total_num;
            ret = checkSingleAof(aof_filename, aof_filepath, last_file, fix, 0);
            printAofStyle(ret, aof_filename, (char *)"INCR AOF");
            sdsfree(aof_filepath);
        }
    }

    aofManifestFree(am);
    printf("All AOF files and manifest are valid\n");
}



/* Check if old style AOF is valid. Internally, it will identify whether 
 * the AOF is in RDB-preamble format, and will eventually call `checkSingleAof`
 * to do the check. */
void checkOldStyleAof(char *filepath, int fix, int preamble) {
    printf("Start checking Old-Style AOF\n");
    int ret = checkSingleAof(filepath, filepath, 1, fix, preamble);
    printAofStyle(ret, filepath, (char *)"AOF");
}

以上都是在校验AOF文件及其完整性