Function _save_plain_upload

Scripts/ButSystem.py:504–534

Save uploaded file to disk quickly (plain) and return size. Speed notes: - Prefer Werkzeug's built-in `save()` which streams efficiently to disk. - Fallback to a large-buffer copy for environments where `save()` misbehaves.

(file_storage, tmp_path: str)

        pass
    return key

MASTER_KEY = load_or_create_master_key()

def aesgcm_encrypt_stream(src_fp, dst_path: str):
    """File format: MAGIC || NONCE || TAG || CIPHERTEXT"""
    nonce = os.urandom(NONCE_LEN)
    cipher = Cipher(algorithms.AES(MASTER_KEY), modes.GCM(nonce))
    encryptor = cipher.encryptor()

    os.makedirs(os.path.dirname(dst_path), exist_ok=True)
    with open(dst_path, "wb") as out:
        out.write(MAGIC)
        out.write(nonce)
        out.write(b"\x00" * TAG_LEN)  # tag placeholder

        while True:
            chunk = src_fp.read(CHUNK)
            if not chunk:
                break
            out.write(encryptor.update(chunk))
        encryptor.finalize()
        tag = encryptor.tag

        out.seek(len(MAGIC) + NONCE_LEN)
        out.write(tag)

def _filestorage_size(file_storage) -> Optional[int]:
    """Return the size (bytes) of an uploaded FileStorage if possible.

    We prefer stream seeking because Content-Length is not always available for
    multipart parts on all clients.
    """
    if file_storage is None:
        return None