Function rewriteClientCommandArgument

app/redis-6.2.6/src/networking.c:3141–3161

Rewrite a single item in the command vector. * The new val ref count is incremented, and the old decremented. * * It is possible to specify an argument over the current size of the * argument vector: in this case the array of objects gets reallocated * and c->argc set to the max value. However it's up to the caller to * * 1. Make sure there are no "holes" and all the arguments are set. * 2

 *    want to end with, it's up to the caller to set c->argc and
 *    free the no longer used objects on c->argv. */
void rewriteClientCommandArgument(client *c, int i, robj *newval) {
    robj *oldval;
    retainOriginalCommandVector(c);
    if (i >= c->argc) {
        c->argv = zrealloc(c->argv,sizeof(robj*)*(i+1));
        c->argc = i+1;
        c->argv[i] = NULL;
    }
    oldval = c->argv[i];
    if (oldval) c->argv_len_sum -= getStringObjectLen(oldval);
    if (newval) c->argv_len_sum += getStringObjectLen(newval);
    c->argv[i] = newval;
    incrRefCount(newval);
    if (oldval) decrRefCount(oldval);

    /* If this is the command name make sure to fix c->cmd. */
    if (i == 0) {
        c->cmd = lookupCommandOrOriginal(c->argv[0]->ptr);
        serverAssertWithInfo(c,NULL,c->cmd != NULL);
    }
}

/* This function returns the number of bytes that Redis is
 * using to store the reply still not read by the client.