Code stuff for FAT32

struct FILE {
    uint32_t curr_cluster;
    uint32_t file_size;
    uint32_t fptr;
    uint32_t buffptr;
    uint8_t currbuf[];
};

FILE *fopen(const char *pathname, const char *mode) {
    FAT32::DirectoryEntry entry;
    if (!EntryForPath(pathname, &entry)) {
        if (entry.name != nullptr)
            free(entry.name);
        return NULL;
    }

    free(entry.name);

    FILE *f = (FILE *)malloc(sizeof(FILE) + FAT32::MasterFS->cluster_size);
    f->curr_cluster = entry.first_cluster;
    f->file_size = entry.file_size;
    f->fptr = 0;
    f->buffptr = 0;
    FAT32::MasterFS->GetCluster(f->currbuf, f->curr_cluster);
    return f;
}

size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t bytes_to_read = size * nmemb;
    size_t bytes_read = 0;

    if (stream->fptr + bytes_to_read > stream->file_size) {
        bytes_to_read = stream->file_size - stream->fptr;
    }

    while (bytes_to_read > 0) {
        if (stream->buffptr + bytes_to_read > FAT32::MasterFS->cluster_size) {
            size_t to_read_in_this_cluster = FAT32::MasterFS->cluster_size - stream->buffptr;
            memcpy((void *)((uint64_t)ptr + bytes_read), stream->currbuf + stream->buffptr, to_read_in_this_cluster);
            bytes_read += to_read_in_this_cluster;
            stream->buffptr = 0;
            stream->curr_cluster = FAT32::MasterFS->GetNextClusterID(stream->curr_cluster);

            if (stream->curr_cluster >= EOC) {

                stream->fptr += bytes_read;
                return bytes_read;
            }

            FAT32::MasterFS->GetCluster(stream->currbuf, stream->curr_cluster);
            bytes_to_read -= to_read_in_this_cluster;
        } else {
            memcpy((void *)((uint64_t)ptr + bytes_read), stream->currbuf + stream->buffptr, bytes_to_read);
            bytes_read += bytes_to_read;
            stream->buffptr += bytes_to_read;
            bytes_to_read = 0;
        }
    }
    stream->fptr += bytes_read;

    return bytes_read;
}