Spaces:
Sleeping
Sleeping
| # -*- coding: utf-8 -*- | |
| # Copyright (c) 2013, Mahmoud Hashemi | |
| # | |
| # Redistribution and use in source and binary forms, with or without | |
| # modification, are permitted provided that the following conditions are | |
| # met: | |
| # | |
| # * Redistributions of source code must retain the above copyright | |
| # notice, this list of conditions and the following disclaimer. | |
| # | |
| # * Redistributions in binary form must reproduce the above | |
| # copyright notice, this list of conditions and the following | |
| # disclaimer in the documentation and/or other materials provided | |
| # with the distribution. | |
| # | |
| # * The names of the contributors may not be used to endorse or | |
| # promote products derived from this software without specific | |
| # prior written permission. | |
| # | |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| """Useful utilities for working with the `mbox`_-formatted | |
| mailboxes. Credit to Mark Williams for these. | |
| .. _mbox: https://en.wikipedia.org/wiki/Mbox | |
| """ | |
| import mailbox | |
| import tempfile | |
| DEFAULT_MAXMEM = 4 * 1024 * 1024 # 4MB | |
| class mbox_readonlydir(mailbox.mbox): | |
| """A subclass of :class:`mailbox.mbox` suitable for use with mboxs | |
| insides a read-only mail directory, e.g., ``/var/mail``. Otherwise | |
| the API is exactly the same as the built-in mbox. | |
| Deletes messages via truncation, in the manner of `Heirloom mailx`_. | |
| Args: | |
| path (str): Path to the mbox file. | |
| factory (type): Message type (defaults to :class:`rfc822.Message`) | |
| create (bool): Create mailbox if it does not exist. (defaults | |
| to ``True``) | |
| maxmem (int): Specifies, in bytes, the largest sized mailbox | |
| to attempt to copy into memory. Larger mailboxes | |
| will be copied incrementally which is more | |
| hazardous. (defaults to 4MB) | |
| .. note:: | |
| Because this truncates and rewrites parts of the mbox file, | |
| this class can corrupt your mailbox. Only use this if you know | |
| the built-in :class:`mailbox.mbox` does not work for your use | |
| case. | |
| .. _Heirloom mailx: http://heirloom.sourceforge.net/mailx.html | |
| """ | |
| def __init__(self, path, factory=None, create=True, maxmem=1024 * 1024): | |
| mailbox.mbox.__init__(self, path, factory, create) | |
| self.maxmem = maxmem | |
| def flush(self): | |
| """Write any pending changes to disk. This is called on mailbox | |
| close and is usually not called explicitly. | |
| .. note:: | |
| This deletes messages via truncation. Interruptions may | |
| corrupt your mailbox. | |
| """ | |
| # Appending and basic assertions are the same as in mailbox.mbox.flush. | |
| if not self._pending: | |
| if self._pending_sync: | |
| # Messages have only been added, so syncing the file | |
| # is enough. | |
| mailbox._sync_flush(self._file) | |
| self._pending_sync = False | |
| return | |
| # In order to be writing anything out at all, self._toc must | |
| # already have been generated (and presumably has been modified | |
| # by adding or deleting an item). | |
| assert self._toc is not None | |
| # Check length of self._file; if it's changed, some other process | |
| # has modified the mailbox since we scanned it. | |
| self._file.seek(0, 2) | |
| cur_len = self._file.tell() | |
| if cur_len != self._file_length: | |
| raise mailbox.ExternalClashError('Size of mailbox file changed ' | |
| '(expected %i, found %i)' % | |
| (self._file_length, cur_len)) | |
| self._file.seek(0) | |
| # Truncation logic begins here. Mostly the same except we | |
| # can use tempfile because we're not doing rename(2). | |
| with tempfile.TemporaryFile() as new_file: | |
| new_toc = {} | |
| self._pre_mailbox_hook(new_file) | |
| for key in sorted(self._toc.keys()): | |
| start, stop = self._toc[key] | |
| self._file.seek(start) | |
| self._pre_message_hook(new_file) | |
| new_start = new_file.tell() | |
| while True: | |
| buffer = self._file.read(min(4096, | |
| stop - self._file.tell())) | |
| if buffer == '': | |
| break | |
| new_file.write(buffer) | |
| new_toc[key] = (new_start, new_file.tell()) | |
| self._post_message_hook(new_file) | |
| self._file_length = new_file.tell() | |
| self._file.seek(0) | |
| new_file.seek(0) | |
| # Copy back our messages | |
| if self._file_length <= self.maxmem: | |
| self._file.write(new_file.read()) | |
| else: | |
| while True: | |
| buffer = new_file.read(4096) | |
| if not buffer: | |
| break | |
| self._file.write(buffer) | |
| # Delete the rest. | |
| self._file.truncate() | |
| # Same wrap up. | |
| self._toc = new_toc | |
| self._pending = False | |
| self._pending_sync = False | |
| if self._locked: | |
| mailbox._lock_file(self._file, dotlock=False) | |