Function parseScanCursorOrReply

app/redis-6.2.6/src/db.c:811–824

Try to parse a SCAN cursor stored at object 'o': * if the cursor is valid, store it as unsigned integer into *cursor and * returns C_OK. Otherwise return C_ERR and send an error to the * client. */

 * returns C_OK. Otherwise return C_ERR and send an error to the
 * client. */
int parseScanCursorOrReply(client *c, robj *o, unsigned long *cursor) {
    char *eptr;

    /* Use strtoul() because we need an *unsigned* long, so
     * getLongLongFromObject() does not cover the whole cursor space. */
    errno = 0;
    *cursor = strtoul(o->ptr, &eptr, 10);
    if (isspace(((char*)o->ptr)[0]) || eptr[0] != '\0' || errno == ERANGE)
    {
        addReplyError(c, "invalid cursor");
        return C_ERR;
    }
    return C_OK;
}

/* This command implements SCAN, HSCAN and SSCAN commands.
 * If object 'o' is passed, then it must be a Hash, Set or Zset object, otherwise