Debug and Fix C Code

Teradata's batch loaders parse fixed-width customer transaction records out of a raw buffer before they're inserted into the warehouse. A junior engineer's first pass at this parser crashes intermittently on real production files.

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

void parse_record(char *buffer, char *out_customer_id, char *out_amount) {
    char customer_id[10];
    strcpy(customer_id, buffer);

    char *amount_field = buffer + 10;
    int amount = atoi(amount_field);

    strcpy(out_customer_id, customer_id);
    sprintf(out_amount, "%d", amount);
}

int process_batch(char **records, int count) {
    int total = 0;
    for (int i = 0; i <= count; i++) {
        char customer_id[10];
        char amount_str[20];
        parse_record(records[i], customer_id, amount_str);
        total += atoi(amount_str);
    }
    return total;
}

Identify all bugs in this C code and describe what problems each one causes. Explain what you'd change to make this safe to run against real production files, without necessarily rewriting every line.