[Zope3-checkins] CVS: Zope3/src/zope/app/mail - maildir.py:1.1

[Marius Gedminas]

Update of /cvs-repository/Zope3/src/zope/app/mail
In directory cvs.zope.org:/tmp/cvs-serv7148/src/zope/app/mail

Added Files:
	maildir.py 
Log Message:
Read-write access for Maildir folders.  First implementation with lots of
XXXes.


=== Added File Zope3/src/zope/app/mail/maildir.py ===
##############################################################################
#
# Copyright (c) 2003 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Read/write access to Maildir folders.

XXX check exception types

$Id: maildir.py,v 1.1 2003/05/21 10:52:52 mgedmin Exp $
"""

import os
import stat
import socket
import time
from zope.interface import implements, classProvides
from zope.app.interfaces.mail import IMaildirFactory, IMaildir
from zope.app.interfaces.mail import IMaildirMessageWriter

__metaclass__ = type

class Maildir:
    """See zope.app.interfaces.mail.IMaildir"""

    classProvides(IMaildirFactory)
    implements(IMaildir)

    def __init__(self, path, create=False):
        "See zope.app.interfaces.mail.IMaildirFactory"
        self.path = path

        def isdir(path):
            return stat.S_ISDIR(os.stat(path)[0])
        def exists(path):
            return os.access(path, os.F_OK)

        subdir_cur = os.path.join(path, 'cur')
        subdir_new = os.path.join(path, 'new')
        subdir_tmp = os.path.join(path, 'tmp')

        if create and not exists(path):
            os.mkdir(path)
            os.mkdir(subdir_cur)
            os.mkdir(subdir_new)
            os.mkdir(subdir_tmp)
            maildir = True
        else:
            maildir = (isdir(subdir_cur) and isdir(subdir_new)
                                         and isdir(subdir_tmp))
        if not maildir:
            raise ValueError('%s is not a Maildir folder' % path)

    def __iter__(self):
        "See zope.app.interfaces.mail.IMaildir"
        join = os.path.join
        subdir_cur = join(self.path, 'cur')
        subdir_new = join(self.path, 'new')
        new_messages = [join(subdir_new, x) for x in os.listdir(subdir_new)]
        cur_messages = [join(subdir_cur, x) for x in os.listdir(subdir_cur)]
        # XXX http://www.qmail.org/man/man5/maildir.html says:
        #     "It is a good idea for readers to skip all filenames in new
        #     and cur starting with a dot.  Other than this, readers
        #     should not attempt to parse filenames."
        return iter(new_messages + cur_messages)

    def newMessage(self):
        "See zope.app.interfaces.mail.IMaildir"
        # XXX http://www.qmail.org/man/man5/maildir.html says, that the first
        #     step of the delivery process should be a chdir.  Chdirs and
        #     threading do not mix.  Is that chdir really necessary?
        join = os.path.join
        subdir_tmp = join(self.path, 'tmp')
        subdir_new = join(self.path, 'new')
        pid = os.getpid()
        host = socket.gethostname()
        counter = 0
        while 1:
            timestamp = int(time.time())
            unique = '%d.%d.%s' % (timestamp, pid, host)
            filename = join(subdir_tmp, unique)
            try:
                os.stat(filename)
            except OSError, e:
                # XXX How can I distinguish ENOENT from other errors?
                break
            else:
                counter += 1
                if counter >= 1000:  # XXX hardcoded magic number
                    raise RuntimeError('Failed to create unique file name in %s,'
                                       ' are we under a DoS attack?' % subdir_tmp)
                # XXX maildir.html (see above) says I should sleep for 2
                # seconds, not 1
                time.sleep(1)
        return MaildirMessageWriter(filename, join(subdir_new, unique))


class MaildirMessageWriter:
    """See zope.app.interfaces.mail.IMaildirMessageWriter"""

    implements(IMaildirMessageWriter)

    def __init__(self, filename, new_filename):
        self._filename = filename
        self._new_filename = new_filename
        self._fd = open(filename, 'w')
        self._closed = False
        self._aborted = False

    def write(self, data):
        self._fd.write(data)

    def writelines(self, lines):
        self._fd.writelines(lines)

    def commit(self):
        if self._closed and self._aborted:
            raise AssertionError('Cannot commit, message already aborted')
        elif not self._closed:
            self._closed = True
            self._aborted = False
            self._fd.close()
            os.rename(self._filename, self._new_filename)
            # XXX the same maildir.html says it should be a link, followed by
            #     unlink.  But Win32 does not necessarily have hardlinks!

    def abort(self):
        if not self._closed:
            self._closed = True
            self._aborted = True
            self._fd.close()
            os.unlink(self._filename)

    # XXX should there be a __del__ that does abort()?