How to realloc another size with realloc

Question

I have a program which takes as input a Name and if the input is less then the allowed size it will be saved in a Pointer.

If the input is bigger then allowed size then the realloc function will be used to satisfy the memory needed. The program at this point allocates only 6 bytes, 5 for name MICHI and 1 for '\0'. If the user types MICHAEL then the program allocates enough memory for that pointer to fit MICHAEL inside that pointer.

Here is the Program:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct person{
    char *name;
}pers;

void addMem(void){
    unsigned int length = 6;
    size_t newLength = 0;
    unsigned int newSize = 0;
    unsigned int i =0;
    char *name;
    int c;

    name = malloc(lenght);
    if(name == NULL){
        exit(1);
    }
    newSize = length;

    printf("Enter your name:>  ");

    while ((c = getchar()) != '\n' && c!=EOF){
        name[i++]=(char)c;

        if(i == newSize){
            newSize = i+length;
            name = realloc(name, newSize);
        }
    }

    name[i] = '\0';

    newLength = strlen(name)+1;
    pers.name = malloc(newLength);

    memcpy(pers.name, name, newLength);

    free(name);
    name = NULL;
}

int main(void){
    addMem();

    printf("Your name is:>  %s\n",pers.name);
    free(pers.name);
    pers.name = NULL;
    return 0;
}

The Program works fine, but I need to make it somehow that realloc() will give only a maximum size of memory, because at this point it will realloc until User pres ENTER.

This means that i have 6 byte for Michi (5 + 1 for '\0') and the maximum size should be 8 (7 for Michael and 1 for '\0').

How can I do that?

EDIT:

I hope you understand now.

My program accept only names with 5 letters. At some point I decided that may program should accept names with max 10 Letters. I allocated already memory for 5 (michi). If you type Michael we have 7 letters so the program should allocate another two for Michael. But if i type Schwarzernegger, well this name is too long i do not accept it so i need to make my program to allocate memory only for michael.

Answer 1

As Enzo's answer to stop after 7 letter you can use.

while ((c = getchar()) != '\n' && c != EOF) {
name[i++] = (char) c;

if (i >= length) {
    if(i+1<=7)
       name = realloc(name, i + 1);
    else
       {
          //generate error message
       }
}
}