Issues writting to existing file on FAT volumes

[deadwood2]

"I've replicated the FAT32 behavior (at least the one from fasttracker2-clone) with a simple code, the code is a lot similar to code used used in ft2-clone.

The program will:
First run
Verify if the new file exist, if not, create new file and exit <= file created successful
Second run
file exist, try to overwrite file <= file become 0KB (should be 1736)
Third run
file exist, wrong size trow error, try to overwrite file <=file is ok again (1736 byte)
Forth run
Same as second (0KCool and so >"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include "unicode/utypes.h"

int main() {
    const char* filename = "FT2.cfg";
    const size_t requiredSize = 1736;

    // Try to open the file in binary read mode
    FILE* file = fopen(filename, "rb");

    if (file == NULL) {
        // File does not exist, create it
        printf("The file does not exist, creating...\n");
        file = fopen(filename, "wb");
        if (file == NULL) {
            printf("Error creating the file!\n");
            return 1;
        }

        // Create a buffer of 1736 bytes and write it to the file
        char buffer[1736] = {0}; // Initialize buffer to zero
        fwrite(buffer, sizeof(char), requiredSize, file);
        fclose(file);
	// Pause and wait for user input
	printf("File created exiting, press any key to continue...\n");	
    	getchar(); // Wait for user to press any key
	return 0;
    } else {
        // File exists, check its size
        fseek(file, 0, SEEK_END);
        long fileSize = ftell(file);
        fclose(file);

        if (fileSize == requiredSize) {
            printf("The file exists, all good.\n");
        } else {
            printf("The file exists, wrong size!\n");
        }
    }

    // Pause and wait for user input
    printf("Trying to overwrite the file, press any key to continue...\n");
    getchar(); // Wait for user to press any key

    // Overwrite the file with 1736 bytes
    file = fopen(filename, "wb");
    if (file == NULL) {
        printf("Error opening the file for writing!\n");
        return 1;
    }

    char buffer[1736] = {0}; // Initialize buffer to zero
    fwrite(buffer, sizeof(char), requiredSize, file);
    fclose(file);

    printf("The file has been overwritten.\n");
    return 0;
}