Function genericGetKeys

app/redis-6.2.6/src/db.c:1677–1698

Helper function to extract keys from following commands: * COMMAND [destkey] [...] [...] ... * * eg: * ZUNION ... * ZUNIONSTORE ... * * 'storeKeyOfs': destkey index, 0 means destkey not exists. * 'keyCountOfs': num-keys index. * 'firstKeyOfs': firstkey index. * 'keySte

 * 'keyStep': the interval of each key, usually this value is 1.
 * */
int genericGetKeys(int storeKeyOfs, int keyCountOfs, int firstKeyOfs, int keyStep,
                    robj **argv, int argc, getKeysResult *result) {
    int i, num, *keys;

    num = atoi(argv[keyCountOfs]->ptr);
    /* Sanity check. Don't return any key if the command is going to
     * reply with syntax error. (no input keys). */
    if (num < 1 || num > (argc - firstKeyOfs)/keyStep) {
        result->numkeys = 0;
        return 0;
    }

    int numkeys = storeKeyOfs ? num + 1 : num;
    keys = getKeysPrepareResult(result, numkeys);
    result->numkeys = numkeys;

    /* Add all key positions for argv[firstKeyOfs...n] to keys[] */
    for (i = 0; i < num; i++) keys[i] = firstKeyOfs+(i*keyStep);

    if (storeKeyOfs) keys[num] = storeKeyOfs;
    return result->numkeys;
}

int zunionInterDiffStoreGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
    UNUSED(cmd);