KV数据库读写加head，解head

typedef struct stKvInfo{
    char *key;
    char *value;
    int keyLen;
    int valLen;
}KvInfo;

void EncodeKvInfo(KvInfo *kvSrc, int srvType)
{
    if (kvSrc == NULL || kvSrc->key == NULL) {
        printf("kvSrc or kvSrc->key is NULL");
        return;
    }
    int tmpKeyLen = kvSrc->keyLen * sizeof(char) + sizeof(int);
    char *tmpKey = (char* )malloc(tmpKeyLen);
    if (tmpKey == NULL) {
        printf("tmpKey is NULL");
        return;
    }
    memset(tmpKey, 0 , tmpKeyLen);
    memcpy(tmpKey, &srvType, sizeof(int));
    memcpy(tmpKey + sizeof(int), kvSrc->key, kvSrc->keyLen * sizeof(char));

    KvInfo kv = {0};
    kv.key = tmpKey;
    kv.value = kvSrc->value;
    kv.keyLen = kvSrc->keyLen + sizeof(int);
    kv.valLen = kvSrc->valLen;
    return ;
}

void DecodeKvInfo(KvInfo *kvdst, int *srvType)
{
    if (kvdst == NULL || kvdst->key == NULL) {
        printf("kvdst or kvdst->key is NULL");
        return;
    }

    int tmpKeySrvLen = sizeof(int);
    char *tmpKeySrv = (char* )malloc(tmpKeySrvLen);
    if (tmpKeySrv == NULL) {
        printf("tmpKey is NULL");
        return;
    }
    memset(tmpKeySrv, 0 , tmpKeySrvLen);
    memcpy(tmpKeySrv, kvdst->key, sizeof(int));
    union u{
        int v;
        char key[4];
    }uu;
    uu.key[0] = tmpKeySrv[0];
    uu.key[1] = tmpKeySrv[1];
    uu.key[2] = tmpKeySrv[2];
    uu.key[3] = tmpKeySrv[3];
    *srvType = uu.v;
    return;
}

void KvInfoPrintf(KvInfo kvSrc)
{
    cout << "-----------------------------" << endl;
    cout << "KEY: " ;
    for (int i = 0; i < kvSrc.keyLen; i++) {
            cout << hex << int(kvSrc.key[i]) << " ";
    }
    cout << endl;
    cout << "VALUE: " << kvSrc.value << endl;
    cout << "KEY LEN: " << kvSrc.keyLen << endl;
    cout << "VALUE LEN: " << kvSrc.valLen << endl;
    cout << "-----------------------------" << endl;
}

int main()
{
    KvInfo kv = {0};
    kv.key = (char*)"key1";
    kv.value = (char*)"value1";
    kv.keyLen = strlen(kv.key);
    kv.valLen = strlen(kv.value);
    KvInfoPrintf(kv);
    EncodeKvInfo(&kv, 123455);
    return 0;
}