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#!/usr/bin/env python |
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# -*- coding: UTF-8 -*- |
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import os |
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import json |
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import base64 |
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import logging |
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import hashlib |
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import zlib |
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from flask import request |
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from browsepy.compat import range |
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from .exceptions import InvalidClipboardSizeError |
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logger = logging.getLogger(__name__) |
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class Clipboard(set): |
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''' |
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Clipboard (set) with convenience methods to pick its state from request |
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cookies and save it to response cookies. |
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''' |
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cookie_secret = os.urandom(256) |
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cookie_name = 'clipboard-{:x}' |
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cookie_path = '/' |
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request_cache_field = '_browsepy_file_actions_clipboard_cache' |
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max_pages = 0xffffffff # 2 ** 32 - 1 |
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@classmethod |
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def count(cls, request=request): |
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''' |
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Get how many clipboard items are stores on request cookies. |
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:param request: optional request, defaults to current flask request |
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:type request: werkzeug.Request |
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:return: number of clipboard items on request's cookies |
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:rtype: int |
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''' |
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return len(cls.from_request(request)) |
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@classmethod |
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def from_request(cls, request=request): |
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''' |
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Create clipboard object from request cookies. |
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Uses request itself for cache. |
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:param request: optional request, defaults to current flask request |
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:type request: werkzeug.Request |
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:returns: clipboard instance |
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:rtype: Clipboard |
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''' |
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cached = getattr(request, cls.request_cache_field, None) |
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if cached is not None: |
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return cached |
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self = cls() |
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setattr(request, cls.request_cache_field, self) |
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try: |
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self.__setstate__(cls._read_paginated_cookie(request)) |
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except: |
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pass |
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return self |
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@classmethod |
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def _paginated_cookie_length(cls, page=0): |
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name_fnc = cls.cookie_name.format |
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return 3990 - len(name_fnc(page) + cls.cookie_path) |
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@classmethod |
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def _read_paginated_cookie(cls, request=request): |
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chunks = [] |
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if request: |
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name_fnc = cls.cookie_name.format |
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for i in range(cls.max_pages): # 2 ** 32 - 1 |
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cookie = request.cookies.get(name_fnc(i), '').encode('ascii') |
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chunks.append(cookie) |
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if len(cookie) < cls._paginated_cookie_length(i): |
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break |
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serialized = zlib.decompress(base64.b64decode(b''.join(chunks))) |
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return json.loads(serialized.decode('utf-8')) |
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@classmethod |
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def _write_paginated_cookie(cls, data, response): |
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serialized = zlib.compress(json.dumps(data).encode('utf-8')) |
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data = base64.b64encode(serialized) |
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name_fnc = cls.cookie_name.format |
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start = 0 |
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size = len(data) |
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for i in range(cls.max_pages): |
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end = cls._paginated_cookie_length(i) |
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response.set_cookie(name_fnc(i), data[start:end].decode('ascii')) |
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start = end |
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if start > size: # we need an empty page after start == size |
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return i |
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raise InvalidClipboardSizeError(max_cookies=cls.max_pages) |
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@classmethod |
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def _delete_paginated_cookie(cls, response, start=0, request=request): |
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name_fnc = cls.cookie_name.format |
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for i in range(start, cls.max_pages): |
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name = name_fnc(i) |
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if name not in request.cookies: |
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break |
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response.set_cookie(name, '', expires=0) |
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@classmethod |
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def _signature(cls, items, method): |
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serialized = json.dumps(items).encode('utf-8') |
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data = cls.cookie_secret + method.encode('utf-8') + serialized |
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return base64.b64encode(hashlib.sha512(data).digest()).decode('ascii') |
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def __init__(self, iterable=(), mode='copy'): |
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self.mode = mode |
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super(Clipboard, self).__init__(iterable) |
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def __getstate__(self): |
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items = list(self) |
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return { |
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'mode': self.mode, |
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'items': items, |
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'signature': self._signature(items, self.mode), |
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} |
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def __setstate__(self, data): |
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if data['signature'] == self._signature(data['items'], data['mode']): |
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self.update(data['items']) |
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self.mode = data['mode'] |
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def to_response(self, response, request=request): |
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''' |
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Save clipboard state to response taking care of disposing old clipboard |
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cookies from request. |
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:param response: response object to write cookies on |
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:type response: werkzeug.Response |
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:param request: optional request, defaults to current flask request |
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:type request: werkzeug.Request |
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''' |
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start = 0 |
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if self: |
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data = self.__getstate__() |
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start = self._write_paginated_cookie(data, response) + 1 |
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self._delete_paginated_cookie(response, start, request) |
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