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1"""Read/write support for Maildir, mbox, MH, Babyl, and MMDF mailboxes."""
2
3# Notes for authors of new mailbox subclasses:
4#
5# Remember to fsync() changes to disk before closing a modified file
6# or returning from a flush() method.  See functions _sync_flush() and
7# _sync_close().
8
9import sys
10import os
11import time
12import calendar
13import socket
14import errno
15import copy
16import email
17import email.message
18import email.generator
19import StringIO
20try:
21    if sys.platform == 'os2emx':
22        # OS/2 EMX fcntl() not adequate
23        raise ImportError
24    import fcntl
25except ImportError:
26    fcntl = None
27
28import warnings
29with warnings.catch_warnings():
30    if sys.py3kwarning:
31        warnings.filterwarnings("ignore", ".*rfc822 has been removed",
32                                DeprecationWarning)
33    import rfc822
34
35__all__ = [ 'Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF',
36            'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage',
37            'BabylMessage', 'MMDFMessage', 'UnixMailbox',
38            'PortableUnixMailbox', 'MmdfMailbox', 'MHMailbox', 'BabylMailbox' ]
39
40class Mailbox:
41    """A group of messages in a particular place."""
42
43    def __init__(self, path, factory=None, create=True):
44        """Initialize a Mailbox instance."""
45        self._path = os.path.abspath(os.path.expanduser(path))
46        self._factory = factory
47
48    def add(self, message):
49        """Add message and return assigned key."""
50        raise NotImplementedError('Method must be implemented by subclass')
51
52    def remove(self, key):
53        """Remove the keyed message; raise KeyError if it doesn't exist."""
54        raise NotImplementedError('Method must be implemented by subclass')
55
56    def __delitem__(self, key):
57        self.remove(key)
58
59    def discard(self, key):
60        """If the keyed message exists, remove it."""
61        try:
62            self.remove(key)
63        except KeyError:
64            pass
65
66    def __setitem__(self, key, message):
67        """Replace the keyed message; raise KeyError if it doesn't exist."""
68        raise NotImplementedError('Method must be implemented by subclass')
69
70    def get(self, key, default=None):
71        """Return the keyed message, or default if it doesn't exist."""
72        try:
73            return self.__getitem__(key)
74        except KeyError:
75            return default
76
77    def __getitem__(self, key):
78        """Return the keyed message; raise KeyError if it doesn't exist."""
79        if not self._factory:
80            return self.get_message(key)
81        else:
82            return self._factory(self.get_file(key))
83
84    def get_message(self, key):
85        """Return a Message representation or raise a KeyError."""
86        raise NotImplementedError('Method must be implemented by subclass')
87
88    def get_string(self, key):
89        """Return a string representation or raise a KeyError."""
90        raise NotImplementedError('Method must be implemented by subclass')
91
92    def get_file(self, key):
93        """Return a file-like representation or raise a KeyError."""
94        raise NotImplementedError('Method must be implemented by subclass')
95
96    def iterkeys(self):
97        """Return an iterator over keys."""
98        raise NotImplementedError('Method must be implemented by subclass')
99
100    def keys(self):
101        """Return a list of keys."""
102        return list(self.iterkeys())
103
104    def itervalues(self):
105        """Return an iterator over all messages."""
106        for key in self.iterkeys():
107            try:
108                value = self[key]
109            except KeyError:
110                continue
111            yield value
112
113    def __iter__(self):
114        return self.itervalues()
115
116    def values(self):
117        """Return a list of messages. Memory intensive."""
118        return list(self.itervalues())
119
120    def iteritems(self):
121        """Return an iterator over (key, message) tuples."""
122        for key in self.iterkeys():
123            try:
124                value = self[key]
125            except KeyError:
126                continue
127            yield (key, value)
128
129    def items(self):
130        """Return a list of (key, message) tuples. Memory intensive."""
131        return list(self.iteritems())
132
133    def has_key(self, key):
134        """Return True if the keyed message exists, False otherwise."""
135        raise NotImplementedError('Method must be implemented by subclass')
136
137    def __contains__(self, key):
138        return self.has_key(key)
139
140    def __len__(self):
141        """Return a count of messages in the mailbox."""
142        raise NotImplementedError('Method must be implemented by subclass')
143
144    def clear(self):
145        """Delete all messages."""
146        for key in self.iterkeys():
147            self.discard(key)
148
149    def pop(self, key, default=None):
150        """Delete the keyed message and return it, or default."""
151        try:
152            result = self[key]
153        except KeyError:
154            return default
155        self.discard(key)
156        return result
157
158    def popitem(self):
159        """Delete an arbitrary (key, message) pair and return it."""
160        for key in self.iterkeys():
161            return (key, self.pop(key))     # This is only run once.
162        else:
163            raise KeyError('No messages in mailbox')
164
165    def update(self, arg=None):
166        """Change the messages that correspond to certain keys."""
167        if hasattr(arg, 'iteritems'):
168            source = arg.iteritems()
169        elif hasattr(arg, 'items'):
170            source = arg.items()
171        else:
172            source = arg
173        bad_key = False
174        for key, message in source:
175            try:
176                self[key] = message
177            except KeyError:
178                bad_key = True
179        if bad_key:
180            raise KeyError('No message with key(s)')
181
182    def flush(self):
183        """Write any pending changes to the disk."""
184        raise NotImplementedError('Method must be implemented by subclass')
185
186    def lock(self):
187        """Lock the mailbox."""
188        raise NotImplementedError('Method must be implemented by subclass')
189
190    def unlock(self):
191        """Unlock the mailbox if it is locked."""
192        raise NotImplementedError('Method must be implemented by subclass')
193
194    def close(self):
195        """Flush and close the mailbox."""
196        raise NotImplementedError('Method must be implemented by subclass')
197
198    # Whether each message must end in a newline
199    _append_newline = False
200
201    def _dump_message(self, message, target, mangle_from_=False):
202        # Most files are opened in binary mode to allow predictable seeking.
203        # To get native line endings on disk, the user-friendly \n line endings
204        # used in strings and by email.Message are translated here.
205        """Dump message contents to target file."""
206        if isinstance(message, email.message.Message):
207            buffer = StringIO.StringIO()
208            gen = email.generator.Generator(buffer, mangle_from_, 0)
209            gen.flatten(message)
210            buffer.seek(0)
211            data = buffer.read().replace('\n', os.linesep)
212            target.write(data)
213            if self._append_newline and not data.endswith(os.linesep):
214                # Make sure the message ends with a newline
215                target.write(os.linesep)
216        elif isinstance(message, str):
217            if mangle_from_:
218                message = message.replace('\nFrom ', '\n>From ')
219            message = message.replace('\n', os.linesep)
220            target.write(message)
221            if self._append_newline and not message.endswith(os.linesep):
222                # Make sure the message ends with a newline
223                target.write(os.linesep)
224        elif hasattr(message, 'read'):
225            lastline = None
226            while True:
227                line = message.readline()
228                if line == '':
229                    break
230                if mangle_from_ and line.startswith('From '):
231                    line = '>From ' + line[5:]
232                line = line.replace('\n', os.linesep)
233                target.write(line)
234                lastline = line
235            if self._append_newline and lastline and not lastline.endswith(os.linesep):
236                # Make sure the message ends with a newline
237                target.write(os.linesep)
238        else:
239            raise TypeError('Invalid message type: %s' % type(message))
240
241
242class Maildir(Mailbox):
243    """A qmail-style Maildir mailbox."""
244
245    colon = ':'
246
247    def __init__(self, dirname, factory=rfc822.Message, create=True):
248        """Initialize a Maildir instance."""
249        Mailbox.__init__(self, dirname, factory, create)
250        self._paths = {
251            'tmp': os.path.join(self._path, 'tmp'),
252            'new': os.path.join(self._path, 'new'),
253            'cur': os.path.join(self._path, 'cur'),
254            }
255        if not os.path.exists(self._path):
256            if create:
257                os.mkdir(self._path, 0700)
258                for path in self._paths.values():
259                    os.mkdir(path, 0o700)
260            else:
261                raise NoSuchMailboxError(self._path)
262        self._toc = {}
263        self._toc_mtimes = {'cur': 0, 'new': 0}
264        self._last_read = 0         # Records last time we read cur/new
265        self._skewfactor = 0.1      # Adjust if os/fs clocks are skewing
266
267    def add(self, message):
268        """Add message and return assigned key."""
269        tmp_file = self._create_tmp()
270        try:
271            self._dump_message(message, tmp_file)
272        except BaseException:
273            tmp_file.close()
274            os.remove(tmp_file.name)
275            raise
276        _sync_close(tmp_file)
277        if isinstance(message, MaildirMessage):
278            subdir = message.get_subdir()
279            suffix = self.colon + message.get_info()
280            if suffix == self.colon:
281                suffix = ''
282        else:
283            subdir = 'new'
284            suffix = ''
285        uniq = os.path.basename(tmp_file.name).split(self.colon)[0]
286        dest = os.path.join(self._path, subdir, uniq + suffix)
287        if isinstance(message, MaildirMessage):
288            os.utime(tmp_file.name,
289                     (os.path.getatime(tmp_file.name), message.get_date()))
290        # No file modification should be done after the file is moved to its
291        # final position in order to prevent race conditions with changes
292        # from other programs
293        try:
294            if hasattr(os, 'link'):
295                os.link(tmp_file.name, dest)
296                os.remove(tmp_file.name)
297            else:
298                os.rename(tmp_file.name, dest)
299        except OSError, e:
300            os.remove(tmp_file.name)
301            if e.errno == errno.EEXIST:
302                raise ExternalClashError('Name clash with existing message: %s'
303                                         % dest)
304            else:
305                raise
306        return uniq
307
308    def remove(self, key):
309        """Remove the keyed message; raise KeyError if it doesn't exist."""
310        os.remove(os.path.join(self._path, self._lookup(key)))
311
312    def discard(self, key):
313        """If the keyed message exists, remove it."""
314        # This overrides an inapplicable implementation in the superclass.
315        try:
316            self.remove(key)
317        except KeyError:
318            pass
319        except OSError, e:
320            if e.errno != errno.ENOENT:
321                raise
322
323    def __setitem__(self, key, message):
324        """Replace the keyed message; raise KeyError if it doesn't exist."""
325        old_subpath = self._lookup(key)
326        temp_key = self.add(message)
327        temp_subpath = self._lookup(temp_key)
328        if isinstance(message, MaildirMessage):
329            # temp's subdir and suffix were specified by message.
330            dominant_subpath = temp_subpath
331        else:
332            # temp's subdir and suffix were defaults from add().
333            dominant_subpath = old_subpath
334        subdir = os.path.dirname(dominant_subpath)
335        if self.colon in dominant_subpath:
336            suffix = self.colon + dominant_subpath.split(self.colon)[-1]
337        else:
338            suffix = ''
339        self.discard(key)
340        tmp_path = os.path.join(self._path, temp_subpath)
341        new_path = os.path.join(self._path, subdir, key + suffix)
342        if isinstance(message, MaildirMessage):
343            os.utime(tmp_path,
344                     (os.path.getatime(tmp_path), message.get_date()))
345        # No file modification should be done after the file is moved to its
346        # final position in order to prevent race conditions with changes
347        # from other programs
348        os.rename(tmp_path, new_path)
349
350    def get_message(self, key):
351        """Return a Message representation or raise a KeyError."""
352        subpath = self._lookup(key)
353        f = open(os.path.join(self._path, subpath), 'r')
354        try:
355            if self._factory:
356                msg = self._factory(f)
357            else:
358                msg = MaildirMessage(f)
359        finally:
360            f.close()
361        subdir, name = os.path.split(subpath)
362        msg.set_subdir(subdir)
363        if self.colon in name:
364            msg.set_info(name.split(self.colon)[-1])
365        msg.set_date(os.path.getmtime(os.path.join(self._path, subpath)))
366        return msg
367
368    def get_string(self, key):
369        """Return a string representation or raise a KeyError."""
370        f = open(os.path.join(self._path, self._lookup(key)), 'r')
371        try:
372            return f.read()
373        finally:
374            f.close()
375
376    def get_file(self, key):
377        """Return a file-like representation or raise a KeyError."""
378        f = open(os.path.join(self._path, self._lookup(key)), 'rb')
379        return _ProxyFile(f)
380
381    def iterkeys(self):
382        """Return an iterator over keys."""
383        self._refresh()
384        for key in self._toc:
385            try:
386                self._lookup(key)
387            except KeyError:
388                continue
389            yield key
390
391    def has_key(self, key):
392        """Return True if the keyed message exists, False otherwise."""
393        self._refresh()
394        return key in self._toc
395
396    def __len__(self):
397        """Return a count of messages in the mailbox."""
398        self._refresh()
399        return len(self._toc)
400
401    def flush(self):
402        """Write any pending changes to disk."""
403        # Maildir changes are always written immediately, so there's nothing
404        # to do.
405        pass
406
407    def lock(self):
408        """Lock the mailbox."""
409        return
410
411    def unlock(self):
412        """Unlock the mailbox if it is locked."""
413        return
414
415    def close(self):
416        """Flush and close the mailbox."""
417        return
418
419    def list_folders(self):
420        """Return a list of folder names."""
421        result = []
422        for entry in os.listdir(self._path):
423            if len(entry) > 1 and entry[0] == '.' and \
424               os.path.isdir(os.path.join(self._path, entry)):
425                result.append(entry[1:])
426        return result
427
428    def get_folder(self, folder):
429        """Return a Maildir instance for the named folder."""
430        return Maildir(os.path.join(self._path, '.' + folder),
431                       factory=self._factory,
432                       create=False)
433
434    def add_folder(self, folder):
435        """Create a folder and return a Maildir instance representing it."""
436        path = os.path.join(self._path, '.' + folder)
437        result = Maildir(path, factory=self._factory)
438        maildirfolder_path = os.path.join(path, 'maildirfolder')
439        if not os.path.exists(maildirfolder_path):
440            os.close(os.open(maildirfolder_path, os.O_CREAT | os.O_WRONLY,
441                0666))
442        return result
443
444    def remove_folder(self, folder):
445        """Delete the named folder, which must be empty."""
446        path = os.path.join(self._path, '.' + folder)
447        for entry in os.listdir(os.path.join(path, 'new')) + \
448                     os.listdir(os.path.join(path, 'cur')):
449            if len(entry) < 1 or entry[0] != '.':
450                raise NotEmptyError('Folder contains message(s): %s' % folder)
451        for entry in os.listdir(path):
452            if entry != 'new' and entry != 'cur' and entry != 'tmp' and \
453               os.path.isdir(os.path.join(path, entry)):
454                raise NotEmptyError("Folder contains subdirectory '%s': %s" %
455                                    (folder, entry))
456        for root, dirs, files in os.walk(path, topdown=False):
457            for entry in files:
458                os.remove(os.path.join(root, entry))
459            for entry in dirs:
460                os.rmdir(os.path.join(root, entry))
461        os.rmdir(path)
462
463    def clean(self):
464        """Delete old files in "tmp"."""
465        now = time.time()
466        for entry in os.listdir(os.path.join(self._path, 'tmp')):
467            path = os.path.join(self._path, 'tmp', entry)
468            if now - os.path.getatime(path) > 129600:   # 60 * 60 * 36
469                os.remove(path)
470
471    _count = 1  # This is used to generate unique file names.
472
473    def _create_tmp(self):
474        """Create a file in the tmp subdirectory and open and return it."""
475        now = time.time()
476        hostname = socket.gethostname()
477        if '/' in hostname:
478            hostname = hostname.replace('/', r'\057')
479        if ':' in hostname:
480            hostname = hostname.replace(':', r'\072')
481        uniq = "%s.M%sP%sQ%s.%s" % (int(now), int(now % 1 * 1e6), os.getpid(),
482                                    Maildir._count, hostname)
483        path = os.path.join(self._path, 'tmp', uniq)
484        try:
485            os.stat(path)
486        except OSError, e:
487            if e.errno == errno.ENOENT:
488                Maildir._count += 1
489                try:
490                    return _create_carefully(path)
491                except OSError, e:
492                    if e.errno != errno.EEXIST:
493                        raise
494            else:
495                raise
496
497        # Fall through to here if stat succeeded or open raised EEXIST.
498        raise ExternalClashError('Name clash prevented file creation: %s' %
499                                 path)
500
501    def _refresh(self):
502        """Update table of contents mapping."""
503        # If it has been less than two seconds since the last _refresh() call,
504        # we have to unconditionally re-read the mailbox just in case it has
505        # been modified, because os.path.mtime() has a 2 sec resolution in the
506        # most common worst case (FAT) and a 1 sec resolution typically.  This
507        # results in a few unnecessary re-reads when _refresh() is called
508        # multiple times in that interval, but once the clock ticks over, we
509        # will only re-read as needed.  Because the filesystem might be being
510        # served by an independent system with its own clock, we record and
511        # compare with the mtimes from the filesystem.  Because the other
512        # system's clock might be skewing relative to our clock, we add an
513        # extra delta to our wait.  The default is one tenth second, but is an
514        # instance variable and so can be adjusted if dealing with a
515        # particularly skewed or irregular system.
516        if time.time() - self._last_read > 2 + self._skewfactor:
517            refresh = False
518            for subdir in self._toc_mtimes:
519                mtime = os.path.getmtime(self._paths[subdir])
520                if mtime > self._toc_mtimes[subdir]:
521                    refresh = True
522                self._toc_mtimes[subdir] = mtime
523            if not refresh:
524                return
525        # Refresh toc
526        self._toc = {}
527        for subdir in self._toc_mtimes:
528            path = self._paths[subdir]
529            for entry in os.listdir(path):
530                p = os.path.join(path, entry)
531                if os.path.isdir(p):
532                    continue
533                uniq = entry.split(self.colon)[0]
534                self._toc[uniq] = os.path.join(subdir, entry)
535        self._last_read = time.time()
536
537    def _lookup(self, key):
538        """Use TOC to return subpath for given key, or raise a KeyError."""
539        try:
540            if os.path.exists(os.path.join(self._path, self._toc[key])):
541                return self._toc[key]
542        except KeyError:
543            pass
544        self._refresh()
545        try:
546            return self._toc[key]
547        except KeyError:
548            raise KeyError('No message with key: %s' % key)
549
550    # This method is for backward compatibility only.
551    def next(self):
552        """Return the next message in a one-time iteration."""
553        if not hasattr(self, '_onetime_keys'):
554            self._onetime_keys = self.iterkeys()
555        while True:
556            try:
557                return self[self._onetime_keys.next()]
558            except StopIteration:
559                return None
560            except KeyError:
561                continue
562
563
564class _singlefileMailbox(Mailbox):
565    """A single-file mailbox."""
566
567    def __init__(self, path, factory=None, create=True):
568        """Initialize a single-file mailbox."""
569        Mailbox.__init__(self, path, factory, create)
570        try:
571            f = open(self._path, 'rb+')
572        except IOError, e:
573            if e.errno == errno.ENOENT:
574                if create:
575                    f = open(self._path, 'wb+')
576                else:
577                    raise NoSuchMailboxError(self._path)
578            elif e.errno in (errno.EACCES, errno.EROFS):
579                f = open(self._path, 'rb')
580            else:
581                raise
582        self._file = f
583        self._toc = None
584        self._next_key = 0
585        self._pending = False       # No changes require rewriting the file.
586        self._pending_sync = False  # No need to sync the file
587        self._locked = False
588        self._file_length = None    # Used to record mailbox size
589
590    def add(self, message):
591        """Add message and return assigned key."""
592        self._lookup()
593        self._toc[self._next_key] = self._append_message(message)
594        self._next_key += 1
595        # _append_message appends the message to the mailbox file. We
596        # don't need a full rewrite + rename, sync is enough.
597        self._pending_sync = True
598        return self._next_key - 1
599
600    def remove(self, key):
601        """Remove the keyed message; raise KeyError if it doesn't exist."""
602        self._lookup(key)
603        del self._toc[key]
604        self._pending = True
605
606    def __setitem__(self, key, message):
607        """Replace the keyed message; raise KeyError if it doesn't exist."""
608        self._lookup(key)
609        self._toc[key] = self._append_message(message)
610        self._pending = True
611
612    def iterkeys(self):
613        """Return an iterator over keys."""
614        self._lookup()
615        for key in self._toc.keys():
616            yield key
617
618    def has_key(self, key):
619        """Return True if the keyed message exists, False otherwise."""
620        self._lookup()
621        return key in self._toc
622
623    def __len__(self):
624        """Return a count of messages in the mailbox."""
625        self._lookup()
626        return len(self._toc)
627
628    def lock(self):
629        """Lock the mailbox."""
630        if not self._locked:
631            _lock_file(self._file)
632            self._locked = True
633
634    def unlock(self):
635        """Unlock the mailbox if it is locked."""
636        if self._locked:
637            _unlock_file(self._file)
638            self._locked = False
639
640    def flush(self):
641        """Write any pending changes to disk."""
642        if not self._pending:
643            if self._pending_sync:
644                # Messages have only been added, so syncing the file
645                # is enough.
646                _sync_flush(self._file)
647                self._pending_sync = False
648            return
649
650        # In order to be writing anything out at all, self._toc must
651        # already have been generated (and presumably has been modified
652        # by adding or deleting an item).
653        assert self._toc is not None
654
655        # Check length of self._file; if it's changed, some other process
656        # has modified the mailbox since we scanned it.
657        self._file.seek(0, 2)
658        cur_len = self._file.tell()
659        if cur_len != self._file_length:
660            raise ExternalClashError('Size of mailbox file changed '
661                                     '(expected %i, found %i)' %
662                                     (self._file_length, cur_len))
663
664        new_file = _create_temporary(self._path)
665        try:
666            new_toc = {}
667            self._pre_mailbox_hook(new_file)
668            for key in sorted(self._toc.keys()):
669                start, stop = self._toc[key]
670                self._file.seek(start)
671                self._pre_message_hook(new_file)
672                new_start = new_file.tell()
673                while True:
674                    buffer = self._file.read(min(4096,
675                                                 stop - self._file.tell()))
676                    if buffer == '':
677                        break
678                    new_file.write(buffer)
679                new_toc[key] = (new_start, new_file.tell())
680                self._post_message_hook(new_file)
681            self._file_length = new_file.tell()
682        except:
683            new_file.close()
684            os.remove(new_file.name)
685            raise
686        _sync_close(new_file)
687        # self._file is about to get replaced, so no need to sync.
688        self._file.close()
689        # Make sure the new file's mode is the same as the old file's
690        mode = os.stat(self._path).st_mode
691        os.chmod(new_file.name, mode)
692        try:
693            os.rename(new_file.name, self._path)
694        except OSError, e:
695            if e.errno == errno.EEXIST or \
696              (os.name == 'os2' and e.errno == errno.EACCES):
697                os.remove(self._path)
698                os.rename(new_file.name, self._path)
699            else:
700                raise
701        self._file = open(self._path, 'rb+')
702        self._toc = new_toc
703        self._pending = False
704        self._pending_sync = False
705        if self._locked:
706            _lock_file(self._file, dotlock=False)
707
708    def _pre_mailbox_hook(self, f):
709        """Called before writing the mailbox to file f."""
710        return
711
712    def _pre_message_hook(self, f):
713        """Called before writing each message to file f."""
714        return
715
716    def _post_message_hook(self, f):
717        """Called after writing each message to file f."""
718        return
719
720    def close(self):
721        """Flush and close the mailbox."""
722        try:
723            self.flush()
724        finally:
725            try:
726                if self._locked:
727                    self.unlock()
728            finally:
729                self._file.close()  # Sync has been done by self.flush() above.
730
731    def _lookup(self, key=None):
732        """Return (start, stop) or raise KeyError."""
733        if self._toc is None:
734            self._generate_toc()
735        if key is not None:
736            try:
737                return self._toc[key]
738            except KeyError:
739                raise KeyError('No message with key: %s' % key)
740
741    def _append_message(self, message):
742        """Append message to mailbox and return (start, stop) offsets."""
743        self._file.seek(0, 2)
744        before = self._file.tell()
745        if len(self._toc) == 0 and not self._pending:
746            # This is the first message, and the _pre_mailbox_hook
747            # hasn't yet been called. If self._pending is True,
748            # messages have been removed, so _pre_mailbox_hook must
749            # have been called already.
750            self._pre_mailbox_hook(self._file)
751        try:
752            self._pre_message_hook(self._file)
753            offsets = self._install_message(message)
754            self._post_message_hook(self._file)
755        except BaseException:
756            self._file.truncate(before)
757            raise
758        self._file.flush()
759        self._file_length = self._file.tell()  # Record current length of mailbox
760        return offsets
761
762
763
764class _mboxMMDF(_singlefileMailbox):
765    """An mbox or MMDF mailbox."""
766
767    _mangle_from_ = True
768
769    def get_message(self, key):
770        """Return a Message representation or raise a KeyError."""
771        start, stop = self._lookup(key)
772        self._file.seek(start)
773        from_line = self._file.readline().replace(os.linesep, '')
774        string = self._file.read(stop - self._file.tell())
775        msg = self._message_factory(string.replace(os.linesep, '\n'))
776        msg.set_from(from_line[5:])
777        return msg
778
779    def get_string(self, key, from_=False):
780        """Return a string representation or raise a KeyError."""
781        start, stop = self._lookup(key)
782        self._file.seek(start)
783        if not from_:
784            self._file.readline()
785        string = self._file.read(stop - self._file.tell())
786        return string.replace(os.linesep, '\n')
787
788    def get_file(self, key, from_=False):
789        """Return a file-like representation or raise a KeyError."""
790        start, stop = self._lookup(key)
791        self._file.seek(start)
792        if not from_:
793            self._file.readline()
794        return _PartialFile(self._file, self._file.tell(), stop)
795
796    def _install_message(self, message):
797        """Format a message and blindly write to self._file."""
798        from_line = None
799        if isinstance(message, str) and message.startswith('From '):
800            newline = message.find('\n')
801            if newline != -1:
802                from_line = message[:newline]
803                message = message[newline + 1:]
804            else:
805                from_line = message
806                message = ''
807        elif isinstance(message, _mboxMMDFMessage):
808            from_line = 'From ' + message.get_from()
809        elif isinstance(message, email.message.Message):
810            from_line = message.get_unixfrom()  # May be None.
811        if from_line is None:
812            from_line = 'From MAILER-DAEMON %s' % time.asctime(time.gmtime())
813        start = self._file.tell()
814        self._file.write(from_line + os.linesep)
815        self._dump_message(message, self._file, self._mangle_from_)
816        stop = self._file.tell()
817        return (start, stop)
818
819
820class mbox(_mboxMMDF):
821    """A classic mbox mailbox."""
822
823    _mangle_from_ = True
824
825    # All messages must end in a newline character, and
826    # _post_message_hooks outputs an empty line between messages.
827    _append_newline = True
828
829    def __init__(self, path, factory=None, create=True):
830        """Initialize an mbox mailbox."""
831        self._message_factory = mboxMessage
832        _mboxMMDF.__init__(self, path, factory, create)
833
834    def _post_message_hook(self, f):
835        """Called after writing each message to file f."""
836        f.write(os.linesep)
837
838    def _generate_toc(self):
839        """Generate key-to-(start, stop) table of contents."""
840        starts, stops = [], []
841        last_was_empty = False
842        self._file.seek(0)
843        while True:
844            line_pos = self._file.tell()
845            line = self._file.readline()
846            if line.startswith('From '):
847                if len(stops) < len(starts):
848                    if last_was_empty:
849                        stops.append(line_pos - len(os.linesep))
850                    else:
851                        # The last line before the "From " line wasn't
852                        # blank, but we consider it a start of a
853                        # message anyway.
854                        stops.append(line_pos)
855                starts.append(line_pos)
856                last_was_empty = False
857            elif not line:
858                if last_was_empty:
859                    stops.append(line_pos - len(os.linesep))
860                else:
861                    stops.append(line_pos)
862                break
863            elif line == os.linesep:
864                last_was_empty = True
865            else:
866                last_was_empty = False
867        self._toc = dict(enumerate(zip(starts, stops)))
868        self._next_key = len(self._toc)
869        self._file_length = self._file.tell()
870
871
872class MMDF(_mboxMMDF):
873    """An MMDF mailbox."""
874
875    def __init__(self, path, factory=None, create=True):
876        """Initialize an MMDF mailbox."""
877        self._message_factory = MMDFMessage
878        _mboxMMDF.__init__(self, path, factory, create)
879
880    def _pre_message_hook(self, f):
881        """Called before writing each message to file f."""
882        f.write('\001\001\001\001' + os.linesep)
883
884    def _post_message_hook(self, f):
885        """Called after writing each message to file f."""
886        f.write(os.linesep + '\001\001\001\001' + os.linesep)
887
888    def _generate_toc(self):
889        """Generate key-to-(start, stop) table of contents."""
890        starts, stops = [], []
891        self._file.seek(0)
892        next_pos = 0
893        while True:
894            line_pos = next_pos
895            line = self._file.readline()
896            next_pos = self._file.tell()
897            if line.startswith('\001\001\001\001' + os.linesep):
898                starts.append(next_pos)
899                while True:
900                    line_pos = next_pos
901                    line = self._file.readline()
902                    next_pos = self._file.tell()
903                    if line == '\001\001\001\001' + os.linesep:
904                        stops.append(line_pos - len(os.linesep))
905                        break
906                    elif line == '':
907                        stops.append(line_pos)
908                        break
909            elif line == '':
910                break
911        self._toc = dict(enumerate(zip(starts, stops)))
912        self._next_key = len(self._toc)
913        self._file.seek(0, 2)
914        self._file_length = self._file.tell()
915
916
917class MH(Mailbox):
918    """An MH mailbox."""
919
920    def __init__(self, path, factory=None, create=True):
921        """Initialize an MH instance."""
922        Mailbox.__init__(self, path, factory, create)
923        if not os.path.exists(self._path):
924            if create:
925                os.mkdir(self._path, 0700)
926                os.close(os.open(os.path.join(self._path, '.mh_sequences'),
927                                 os.O_CREAT | os.O_EXCL | os.O_WRONLY, 0600))
928            else:
929                raise NoSuchMailboxError(self._path)
930        self._locked = False
931
932    def add(self, message):
933        """Add message and return assigned key."""
934        keys = self.keys()
935        if len(keys) == 0:
936            new_key = 1
937        else:
938            new_key = max(keys) + 1
939        new_path = os.path.join(self._path, str(new_key))
940        f = _create_carefully(new_path)
941        closed = False
942        try:
943            if self._locked:
944                _lock_file(f)
945            try:
946                try:
947                    self._dump_message(message, f)
948                except BaseException:
949                    # Unlock and close so it can be deleted on Windows
950                    if self._locked:
951                        _unlock_file(f)
952                    _sync_close(f)
953                    closed = True
954                    os.remove(new_path)
955                    raise
956                if isinstance(message, MHMessage):
957                    self._dump_sequences(message, new_key)
958            finally:
959                if self._locked:
960                    _unlock_file(f)
961        finally:
962            if not closed:
963                _sync_close(f)
964        return new_key
965
966    def remove(self, key):
967        """Remove the keyed message; raise KeyError if it doesn't exist."""
968        path = os.path.join(self._path, str(key))
969        try:
970            f = open(path, 'rb+')
971        except IOError, e:
972            if e.errno == errno.ENOENT:
973                raise KeyError('No message with key: %s' % key)
974            else:
975                raise
976        else:
977            f.close()
978            os.remove(path)
979
980    def __setitem__(self, key, message):
981        """Replace the keyed message; raise KeyError if it doesn't exist."""
982        path = os.path.join(self._path, str(key))
983        try:
984            f = open(path, 'rb+')
985        except IOError, e:
986            if e.errno == errno.ENOENT:
987                raise KeyError('No message with key: %s' % key)
988            else:
989                raise
990        try:
991            if self._locked:
992                _lock_file(f)
993            try:
994                os.close(os.open(path, os.O_WRONLY | os.O_TRUNC))
995                self._dump_message(message, f)
996                if isinstance(message, MHMessage):
997                    self._dump_sequences(message, key)
998            finally:
999                if self._locked:
1000                    _unlock_file(f)
1001        finally:
1002            _sync_close(f)
1003
1004    def get_message(self, key):
1005        """Return a Message representation or raise a KeyError."""
1006        try:
1007            if self._locked:
1008                f = open(os.path.join(self._path, str(key)), 'r+')
1009            else:
1010                f = open(os.path.join(self._path, str(key)), 'r')
1011        except IOError, e:
1012            if e.errno == errno.ENOENT:
1013                raise KeyError('No message with key: %s' % key)
1014            else:
1015                raise
1016        try:
1017            if self._locked:
1018                _lock_file(f)
1019            try:
1020                msg = MHMessage(f)
1021            finally:
1022                if self._locked:
1023                    _unlock_file(f)
1024        finally:
1025            f.close()
1026        for name, key_list in self.get_sequences().iteritems():
1027            if key in key_list:
1028                msg.add_sequence(name)
1029        return msg
1030
1031    def get_string(self, key):
1032        """Return a string representation or raise a KeyError."""
1033        try:
1034            if self._locked:
1035                f = open(os.path.join(self._path, str(key)), 'r+')
1036            else:
1037                f = open(os.path.join(self._path, str(key)), 'r')
1038        except IOError, e:
1039            if e.errno == errno.ENOENT:
1040                raise KeyError('No message with key: %s' % key)
1041            else:
1042                raise
1043        try:
1044            if self._locked:
1045                _lock_file(f)
1046            try:
1047                return f.read()
1048            finally:
1049                if self._locked:
1050                    _unlock_file(f)
1051        finally:
1052            f.close()
1053
1054    def get_file(self, key):
1055        """Return a file-like representation or raise a KeyError."""
1056        try:
1057            f = open(os.path.join(self._path, str(key)), 'rb')
1058        except IOError, e:
1059            if e.errno == errno.ENOENT:
1060                raise KeyError('No message with key: %s' % key)
1061            else:
1062                raise
1063        return _ProxyFile(f)
1064
1065    def iterkeys(self):
1066        """Return an iterator over keys."""
1067        return iter(sorted(int(entry) for entry in os.listdir(self._path)
1068                                      if entry.isdigit()))
1069
1070    def has_key(self, key):
1071        """Return True if the keyed message exists, False otherwise."""
1072        return os.path.exists(os.path.join(self._path, str(key)))
1073
1074    def __len__(self):
1075        """Return a count of messages in the mailbox."""
1076        return len(list(self.iterkeys()))
1077
1078    def lock(self):
1079        """Lock the mailbox."""
1080        if not self._locked:
1081            self._file = open(os.path.join(self._path, '.mh_sequences'), 'rb+')
1082            _lock_file(self._file)
1083            self._locked = True
1084
1085    def unlock(self):
1086        """Unlock the mailbox if it is locked."""
1087        if self._locked:
1088            _unlock_file(self._file)
1089            _sync_close(self._file)
1090            del self._file
1091            self._locked = False
1092
1093    def flush(self):
1094        """Write any pending changes to the disk."""
1095        return
1096
1097    def close(self):
1098        """Flush and close the mailbox."""
1099        if self._locked:
1100            self.unlock()
1101
1102    def list_folders(self):
1103        """Return a list of folder names."""
1104        result = []
1105        for entry in os.listdir(self._path):
1106            if os.path.isdir(os.path.join(self._path, entry)):
1107                result.append(entry)
1108        return result
1109
1110    def get_folder(self, folder):
1111        """Return an MH instance for the named folder."""
1112        return MH(os.path.join(self._path, folder),
1113                  factory=self._factory, create=False)
1114
1115    def add_folder(self, folder):
1116        """Create a folder and return an MH instance representing it."""
1117        return MH(os.path.join(self._path, folder),
1118                  factory=self._factory)
1119
1120    def remove_folder(self, folder):
1121        """Delete the named folder, which must be empty."""
1122        path = os.path.join(self._path, folder)
1123        entries = os.listdir(path)
1124        if entries == ['.mh_sequences']:
1125            os.remove(os.path.join(path, '.mh_sequences'))
1126        elif entries == []:
1127            pass
1128        else:
1129            raise NotEmptyError('Folder not empty: %s' % self._path)
1130        os.rmdir(path)
1131
1132    def get_sequences(self):
1133        """Return a name-to-key-list dictionary to define each sequence."""
1134        results = {}
1135        f = open(os.path.join(self._path, '.mh_sequences'), 'r')
1136        try:
1137            all_keys = set(self.keys())
1138            for line in f:
1139                try:
1140                    name, contents = line.split(':')
1141                    keys = set()
1142                    for spec in contents.split():
1143                        if spec.isdigit():
1144                            keys.add(int(spec))
1145                        else:
1146                            start, stop = (int(x) for x in spec.split('-'))
1147                            keys.update(range(start, stop + 1))
1148                    results[name] = [key for key in sorted(keys) \
1149                                         if key in all_keys]
1150                    if len(results[name]) == 0:
1151                        del results[name]
1152                except ValueError:
1153                    raise FormatError('Invalid sequence specification: %s' %
1154                                      line.rstrip())
1155        finally:
1156            f.close()
1157        return results
1158
1159    def set_sequences(self, sequences):
1160        """Set sequences using the given name-to-key-list dictionary."""
1161        f = open(os.path.join(self._path, '.mh_sequences'), 'r+')
1162        try:
1163            os.close(os.open(f.name, os.O_WRONLY | os.O_TRUNC))
1164            for name, keys in sequences.iteritems():
1165                if len(keys) == 0:
1166                    continue
1167                f.write('%s:' % name)
1168                prev = None
1169                completing = False
1170                for key in sorted(set(keys)):
1171                    if key - 1 == prev:
1172                        if not completing:
1173                            completing = True
1174                            f.write('-')
1175                    elif completing:
1176                        completing = False
1177                        f.write('%s %s' % (prev, key))
1178                    else:
1179                        f.write(' %s' % key)
1180                    prev = key
1181                if completing:
1182                    f.write(str(prev) + '\n')
1183                else:
1184                    f.write('\n')
1185        finally:
1186            _sync_close(f)
1187
1188    def pack(self):
1189        """Re-name messages to eliminate numbering gaps. Invalidates keys."""
1190        sequences = self.get_sequences()
1191        prev = 0
1192        changes = []
1193        for key in self.iterkeys():
1194            if key - 1 != prev:
1195                changes.append((key, prev + 1))
1196                if hasattr(os, 'link'):
1197                    os.link(os.path.join(self._path, str(key)),
1198                            os.path.join(self._path, str(prev + 1)))
1199                    os.unlink(os.path.join(self._path, str(key)))
1200                else:
1201                    os.rename(os.path.join(self._path, str(key)),
1202                              os.path.join(self._path, str(prev + 1)))
1203            prev += 1
1204        self._next_key = prev + 1
1205        if len(changes) == 0:
1206            return
1207        for name, key_list in sequences.items():
1208            for old, new in changes:
1209                if old in key_list:
1210                    key_list[key_list.index(old)] = new
1211        self.set_sequences(sequences)
1212
1213    def _dump_sequences(self, message, key):
1214        """Inspect a new MHMessage and update sequences appropriately."""
1215        pending_sequences = message.get_sequences()
1216        all_sequences = self.get_sequences()
1217        for name, key_list in all_sequences.iteritems():
1218            if name in pending_sequences:
1219                key_list.append(key)
1220            elif key in key_list:
1221                del key_list[key_list.index(key)]
1222        for sequence in pending_sequences:
1223            if sequence not in all_sequences:
1224                all_sequences[sequence] = [key]
1225        self.set_sequences(all_sequences)
1226
1227
1228class Babyl(_singlefileMailbox):
1229    """An Rmail-style Babyl mailbox."""
1230
1231    _special_labels = frozenset(('unseen', 'deleted', 'filed', 'answered',
1232                                 'forwarded', 'edited', 'resent'))
1233
1234    def __init__(self, path, factory=None, create=True):
1235        """Initialize a Babyl mailbox."""
1236        _singlefileMailbox.__init__(self, path, factory, create)
1237        self._labels = {}
1238
1239    def add(self, message):
1240        """Add message and return assigned key."""
1241        key = _singlefileMailbox.add(self, message)
1242        if isinstance(message, BabylMessage):
1243            self._labels[key] = message.get_labels()
1244        return key
1245
1246    def remove(self, key):
1247        """Remove the keyed message; raise KeyError if it doesn't exist."""
1248        _singlefileMailbox.remove(self, key)
1249        if key in self._labels:
1250            del self._labels[key]
1251
1252    def __setitem__(self, key, message):
1253        """Replace the keyed message; raise KeyError if it doesn't exist."""
1254        _singlefileMailbox.__setitem__(self, key, message)
1255        if isinstance(message, BabylMessage):
1256            self._labels[key] = message.get_labels()
1257
1258    def get_message(self, key):
1259        """Return a Message representation or raise a KeyError."""
1260        start, stop = self._lookup(key)
1261        self._file.seek(start)
1262        self._file.readline()   # Skip '1,' line specifying labels.
1263        original_headers = StringIO.StringIO()
1264        while True:
1265            line = self._file.readline()
1266            if line == '*** EOOH ***' + os.linesep or line == '':
1267                break
1268            original_headers.write(line.replace(os.linesep, '\n'))
1269        visible_headers = StringIO.StringIO()
1270        while True:
1271            line = self._file.readline()
1272            if line == os.linesep or line == '':
1273                break
1274            visible_headers.write(line.replace(os.linesep, '\n'))
1275        body = self._file.read(stop - self._file.tell()).replace(os.linesep,
1276                                                                 '\n')
1277        msg = BabylMessage(original_headers.getvalue() + body)
1278        msg.set_visible(visible_headers.getvalue())
1279        if key in self._labels:
1280            msg.set_labels(self._labels[key])
1281        return msg
1282
1283    def get_string(self, key):
1284        """Return a string representation or raise a KeyError."""
1285        start, stop = self._lookup(key)
1286        self._file.seek(start)
1287        self._file.readline()   # Skip '1,' line specifying labels.
1288        original_headers = StringIO.StringIO()
1289        while True:
1290            line = self._file.readline()
1291            if line == '*** EOOH ***' + os.linesep or line == '':
1292                break
1293            original_headers.write(line.replace(os.linesep, '\n'))
1294        while True:
1295            line = self._file.readline()
1296            if line == os.linesep or line == '':
1297                break
1298        return original_headers.getvalue() + \
1299               self._file.read(stop - self._file.tell()).replace(os.linesep,
1300                                                                 '\n')
1301
1302    def get_file(self, key):
1303        """Return a file-like representation or raise a KeyError."""
1304        return StringIO.StringIO(self.get_string(key).replace('\n',
1305                                                              os.linesep))
1306
1307    def get_labels(self):
1308        """Return a list of user-defined labels in the mailbox."""
1309        self._lookup()
1310        labels = set()
1311        for label_list in self._labels.values():
1312            labels.update(label_list)
1313        labels.difference_update(self._special_labels)
1314        return list(labels)
1315
1316    def _generate_toc(self):
1317        """Generate key-to-(start, stop) table of contents."""
1318        starts, stops = [], []
1319        self._file.seek(0)
1320        next_pos = 0
1321        label_lists = []
1322        while True:
1323            line_pos = next_pos
1324            line = self._file.readline()
1325            next_pos = self._file.tell()
1326            if line == '\037\014' + os.linesep:
1327                if len(stops) < len(starts):
1328                    stops.append(line_pos - len(os.linesep))
1329                starts.append(next_pos)
1330                labels = [label.strip() for label
1331                                        in self._file.readline()[1:].split(',')
1332                                        if label.strip() != '']
1333                label_lists.append(labels)
1334            elif line == '\037' or line == '\037' + os.linesep:
1335                if len(stops) < len(starts):
1336                    stops.append(line_pos - len(os.linesep))
1337            elif line == '':
1338                stops.append(line_pos - len(os.linesep))
1339                break
1340        self._toc = dict(enumerate(zip(starts, stops)))
1341        self._labels = dict(enumerate(label_lists))
1342        self._next_key = len(self._toc)
1343        self._file.seek(0, 2)
1344        self._file_length = self._file.tell()
1345
1346    def _pre_mailbox_hook(self, f):
1347        """Called before writing the mailbox to file f."""
1348        f.write('BABYL OPTIONS:%sVersion: 5%sLabels:%s%s\037' %
1349                (os.linesep, os.linesep, ','.join(self.get_labels()),
1350                 os.linesep))
1351
1352    def _pre_message_hook(self, f):
1353        """Called before writing each message to file f."""
1354        f.write('\014' + os.linesep)
1355
1356    def _post_message_hook(self, f):
1357        """Called after writing each message to file f."""
1358        f.write(os.linesep + '\037')
1359
1360    def _install_message(self, message):
1361        """Write message contents and return (start, stop)."""
1362        start = self._file.tell()
1363        if isinstance(message, BabylMessage):
1364            special_labels = []
1365            labels = []
1366            for label in message.get_labels():
1367                if label in self._special_labels:
1368                    special_labels.append(label)
1369                else:
1370                    labels.append(label)
1371            self._file.write('1')
1372            for label in special_labels:
1373                self._file.write(', ' + label)
1374            self._file.write(',,')
1375            for label in labels:
1376                self._file.write(' ' + label + ',')
1377            self._file.write(os.linesep)
1378        else:
1379            self._file.write('1,,' + os.linesep)
1380        if isinstance(message, email.message.Message):
1381            orig_buffer = StringIO.StringIO()
1382            orig_generator = email.generator.Generator(orig_buffer, False, 0)
1383            orig_generator.flatten(message)
1384            orig_buffer.seek(0)
1385            while True:
1386                line = orig_buffer.readline()
1387                self._file.write(line.replace('\n', os.linesep))
1388                if line == '\n' or line == '':
1389                    break
1390            self._file.write('*** EOOH ***' + os.linesep)
1391            if isinstance(message, BabylMessage):
1392                vis_buffer = StringIO.StringIO()
1393                vis_generator = email.generator.Generator(vis_buffer, False, 0)
1394                vis_generator.flatten(message.get_visible())
1395                while True:
1396                    line = vis_buffer.readline()
1397                    self._file.write(line.replace('\n', os.linesep))
1398                    if line == '\n' or line == '':
1399                        break
1400            else:
1401                orig_buffer.seek(0)
1402                while True:
1403                    line = orig_buffer.readline()
1404                    self._file.write(line.replace('\n', os.linesep))
1405                    if line == '\n' or line == '':
1406                        break
1407            while True:
1408                buffer = orig_buffer.read(4096) # Buffer size is arbitrary.
1409                if buffer == '':
1410                    break
1411                self._file.write(buffer.replace('\n', os.linesep))
1412        elif isinstance(message, str):
1413            body_start = message.find('\n\n') + 2
1414            if body_start - 2 != -1:
1415                self._file.write(message[:body_start].replace('\n',
1416                                                              os.linesep))
1417                self._file.write('*** EOOH ***' + os.linesep)
1418                self._file.write(message[:body_start].replace('\n',
1419                                                              os.linesep))
1420                self._file.write(message[body_start:].replace('\n',
1421                                                              os.linesep))
1422            else:
1423                self._file.write('*** EOOH ***' + os.linesep + os.linesep)
1424                self._file.write(message.replace('\n', os.linesep))
1425        elif hasattr(message, 'readline'):
1426            original_pos = message.tell()
1427            first_pass = True
1428            while True:
1429                line = message.readline()
1430                self._file.write(line.replace('\n', os.linesep))
1431                if line == '\n' or line == '':
1432                    if first_pass:
1433                        first_pass = False
1434                        self._file.write('*** EOOH ***' + os.linesep)
1435                        message.seek(original_pos)
1436                    else:
1437                        break
1438            while True:
1439                buffer = message.read(4096)     # Buffer size is arbitrary.
1440                if buffer == '':
1441                    break
1442                self._file.write(buffer.replace('\n', os.linesep))
1443        else:
1444            raise TypeError('Invalid message type: %s' % type(message))
1445        stop = self._file.tell()
1446        return (start, stop)
1447
1448
1449class Message(email.message.Message):
1450    """Message with mailbox-format-specific properties."""
1451
1452    def __init__(self, message=None):
1453        """Initialize a Message instance."""
1454        if isinstance(message, email.message.Message):
1455            self._become_message(copy.deepcopy(message))
1456            if isinstance(message, Message):
1457                message._explain_to(self)
1458        elif isinstance(message, str):
1459            self._become_message(email.message_from_string(message))
1460        elif hasattr(message, "read"):
1461            self._become_message(email.message_from_file(message))
1462        elif message is None:
1463            email.message.Message.__init__(self)
1464        else:
1465            raise TypeError('Invalid message type: %s' % type(message))
1466
1467    def _become_message(self, message):
1468        """Assume the non-format-specific state of message."""
1469        for name in ('_headers', '_unixfrom', '_payload', '_charset',
1470                     'preamble', 'epilogue', 'defects', '_default_type'):
1471            self.__dict__[name] = message.__dict__[name]
1472
1473    def _explain_to(self, message):
1474        """Copy format-specific state to message insofar as possible."""
1475        if isinstance(message, Message):
1476            return  # There's nothing format-specific to explain.
1477        else:
1478            raise TypeError('Cannot convert to specified type')
1479
1480
1481class MaildirMessage(Message):
1482    """Message with Maildir-specific properties."""
1483
1484    def __init__(self, message=None):
1485        """Initialize a MaildirMessage instance."""
1486        self._subdir = 'new'
1487        self._info = ''
1488        self._date = time.time()
1489        Message.__init__(self, message)
1490
1491    def get_subdir(self):
1492        """Return 'new' or 'cur'."""
1493        return self._subdir
1494
1495    def set_subdir(self, subdir):
1496        """Set subdir to 'new' or 'cur'."""
1497        if subdir == 'new' or subdir == 'cur':
1498            self._subdir = subdir
1499        else:
1500            raise ValueError("subdir must be 'new' or 'cur': %s" % subdir)
1501
1502    def get_flags(self):
1503        """Return as a string the flags that are set."""
1504        if self._info.startswith('2,'):
1505            return self._info[2:]
1506        else:
1507            return ''
1508
1509    def set_flags(self, flags):
1510        """Set the given flags and unset all others."""
1511        self._info = '2,' + ''.join(sorted(flags))
1512
1513    def add_flag(self, flag):
1514        """Set the given flag(s) without changing others."""
1515        self.set_flags(''.join(set(self.get_flags()) | set(flag)))
1516
1517    def remove_flag(self, flag):
1518        """Unset the given string flag(s) without changing others."""
1519        if self.get_flags() != '':
1520            self.set_flags(''.join(set(self.get_flags()) - set(flag)))
1521
1522    def get_date(self):
1523        """Return delivery date of message, in seconds since the epoch."""
1524        return self._date
1525
1526    def set_date(self, date):
1527        """Set delivery date of message, in seconds since the epoch."""
1528        try:
1529            self._date = float(date)
1530        except ValueError:
1531            raise TypeError("can't convert to float: %s" % date)
1532
1533    def get_info(self):
1534        """Get the message's "info" as a string."""
1535        return self._info
1536
1537    def set_info(self, info):
1538        """Set the message's "info" string."""
1539        if isinstance(info, str):
1540            self._info = info
1541        else:
1542            raise TypeError('info must be a string: %s' % type(info))
1543
1544    def _explain_to(self, message):
1545        """Copy Maildir-specific state to message insofar as possible."""
1546        if isinstance(message, MaildirMessage):
1547            message.set_flags(self.get_flags())
1548            message.set_subdir(self.get_subdir())
1549            message.set_date(self.get_date())
1550        elif isinstance(message, _mboxMMDFMessage):
1551            flags = set(self.get_flags())
1552            if 'S' in flags:
1553                message.add_flag('R')
1554            if self.get_subdir() == 'cur':
1555                message.add_flag('O')
1556            if 'T' in flags:
1557                message.add_flag('D')
1558            if 'F' in flags:
1559                message.add_flag('F')
1560            if 'R' in flags:
1561                message.add_flag('A')
1562            message.set_from('MAILER-DAEMON', time.gmtime(self.get_date()))
1563        elif isinstance(message, MHMessage):
1564            flags = set(self.get_flags())
1565            if 'S' not in flags:
1566                message.add_sequence('unseen')
1567            if 'R' in flags:
1568                message.add_sequence('replied')
1569            if 'F' in flags:
1570                message.add_sequence('flagged')
1571        elif isinstance(message, BabylMessage):
1572            flags = set(self.get_flags())
1573            if 'S' not in flags:
1574                message.add_label('unseen')
1575            if 'T' in flags:
1576                message.add_label('deleted')
1577            if 'R' in flags:
1578                message.add_label('answered')
1579            if 'P' in flags:
1580                message.add_label('forwarded')
1581        elif isinstance(message, Message):
1582            pass
1583        else:
1584            raise TypeError('Cannot convert to specified type: %s' %
1585                            type(message))
1586
1587
1588class _mboxMMDFMessage(Message):
1589    """Message with mbox- or MMDF-specific properties."""
1590
1591    def __init__(self, message=None):
1592        """Initialize an mboxMMDFMessage instance."""
1593        self.set_from('MAILER-DAEMON', True)
1594        if isinstance(message, email.message.Message):
1595            unixfrom = message.get_unixfrom()
1596            if unixfrom is not None and unixfrom.startswith('From '):
1597                self.set_from(unixfrom[5:])
1598        Message.__init__(self, message)
1599
1600    def get_from(self):
1601        """Return contents of "From " line."""
1602        return self._from
1603
1604    def set_from(self, from_, time_=None):
1605        """Set "From " line, formatting and appending time_ if specified."""
1606        if time_ is not None:
1607            if time_ is True:
1608                time_ = time.gmtime()
1609            from_ += ' ' + time.asctime(time_)
1610        self._from = from_
1611
1612    def get_flags(self):
1613        """Return as a string the flags that are set."""
1614        return self.get('Status', '') + self.get('X-Status', '')
1615
1616    def set_flags(self, flags):
1617        """Set the given flags and unset all others."""
1618        flags = set(flags)
1619        status_flags, xstatus_flags = '', ''
1620        for flag in ('R', 'O'):
1621            if flag in flags:
1622                status_flags += flag
1623                flags.remove(flag)
1624        for flag in ('D', 'F', 'A'):
1625            if flag in flags:
1626                xstatus_flags += flag
1627                flags.remove(flag)
1628        xstatus_flags += ''.join(sorted(flags))
1629        try:
1630            self.replace_header('Status', status_flags)
1631        except KeyError:
1632            self.add_header('Status', status_flags)
1633        try:
1634            self.replace_header('X-Status', xstatus_flags)
1635        except KeyError:
1636            self.add_header('X-Status', xstatus_flags)
1637
1638    def add_flag(self, flag):
1639        """Set the given flag(s) without changing others."""
1640        self.set_flags(''.join(set(self.get_flags()) | set(flag)))
1641
1642    def remove_flag(self, flag):
1643        """Unset the given string flag(s) without changing others."""
1644        if 'Status' in self or 'X-Status' in self:
1645            self.set_flags(''.join(set(self.get_flags()) - set(flag)))
1646
1647    def _explain_to(self, message):
1648        """Copy mbox- or MMDF-specific state to message insofar as possible."""
1649        if isinstance(message, MaildirMessage):
1650            flags = set(self.get_flags())
1651            if 'O' in flags:
1652                message.set_subdir('cur')
1653            if 'F' in flags:
1654                message.add_flag('F')
1655            if 'A' in flags:
1656                message.add_flag('R')
1657            if 'R' in flags:
1658                message.add_flag('S')
1659            if 'D' in flags:
1660                message.add_flag('T')
1661            del message['status']
1662            del message['x-status']
1663            maybe_date = ' '.join(self.get_from().split()[-5:])
1664            try:
1665                message.set_date(calendar.timegm(time.strptime(maybe_date,
1666                                                      '%a %b %d %H:%M:%S %Y')))
1667            except (ValueError, OverflowError):
1668                pass
1669        elif isinstance(message, _mboxMMDFMessage):
1670            message.set_flags(self.get_flags())
1671            message.set_from(self.get_from())
1672        elif isinstance(message, MHMessage):
1673            flags = set(self.get_flags())
1674            if 'R' not in flags:
1675                message.add_sequence('unseen')
1676            if 'A' in flags:
1677                message.add_sequence('replied')
1678            if 'F' in flags:
1679                message.add_sequence('flagged')
1680            del message['status']
1681            del message['x-status']
1682        elif isinstance(message, BabylMessage):
1683            flags = set(self.get_flags())
1684            if 'R' not in flags:
1685                message.add_label('unseen')
1686            if 'D' in flags:
1687                message.add_label('deleted')
1688            if 'A' in flags:
1689                message.add_label('answered')
1690            del message['status']
1691            del message['x-status']
1692        elif isinstance(message, Message):
1693            pass
1694        else:
1695            raise TypeError('Cannot convert to specified type: %s' %
1696                            type(message))
1697
1698
1699class mboxMessage(_mboxMMDFMessage):
1700    """Message with mbox-specific properties."""
1701
1702
1703class MHMessage(Message):
1704    """Message with MH-specific properties."""
1705
1706    def __init__(self, message=None):
1707        """Initialize an MHMessage instance."""
1708        self._sequences = []
1709        Message.__init__(self, message)
1710
1711    def get_sequences(self):
1712        """Return a list of sequences that include the message."""
1713        return self._sequences[:]
1714
1715    def set_sequences(self, sequences):
1716        """Set the list of sequences that include the message."""
1717        self._sequences = list(sequences)
1718
1719    def add_sequence(self, sequence):
1720        """Add sequence to list of sequences including the message."""
1721        if isinstance(sequence, str):
1722            if not sequence in self._sequences:
1723                self._sequences.append(sequence)
1724        else:
1725            raise TypeError('sequence must be a string: %s' % type(sequence))
1726
1727    def remove_sequence(self, sequence):
1728        """Remove sequence from the list of sequences including the message."""
1729        try:
1730            self._sequences.remove(sequence)
1731        except ValueError:
1732            pass
1733
1734    def _explain_to(self, message):
1735        """Copy MH-specific state to message insofar as possible."""
1736        if isinstance(message, MaildirMessage):
1737            sequences = set(self.get_sequences())
1738            if 'unseen' in sequences:
1739                message.set_subdir('cur')
1740            else:
1741                message.set_subdir('cur')
1742                message.add_flag('S')
1743            if 'flagged' in sequences:
1744                message.add_flag('F')
1745            if 'replied' in sequences:
1746                message.add_flag('R')
1747        elif isinstance(message, _mboxMMDFMessage):
1748            sequences = set(self.get_sequences())
1749            if 'unseen' not in sequences:
1750                message.add_flag('RO')
1751            else:
1752                message.add_flag('O')
1753            if 'flagged' in sequences:
1754                message.add_flag('F')
1755            if 'replied' in sequences:
1756                message.add_flag('A')
1757        elif isinstance(message, MHMessage):
1758            for sequence in self.get_sequences():
1759                message.add_sequence(sequence)
1760        elif isinstance(message, BabylMessage):
1761            sequences = set(self.get_sequences())
1762            if 'unseen' in sequences:
1763                message.add_label('unseen')
1764            if 'replied' in sequences:
1765                message.add_label('answered')
1766        elif isinstance(message, Message):
1767            pass
1768        else:
1769            raise TypeError('Cannot convert to specified type: %s' %
1770                            type(message))
1771
1772
1773class BabylMessage(Message):
1774    """Message with Babyl-specific properties."""
1775
1776    def __init__(self, message=None):
1777        """Initialize a BabylMessage instance."""
1778        self._labels = []
1779        self._visible = Message()
1780        Message.__init__(self, message)
1781
1782    def get_labels(self):
1783        """Return a list of labels on the message."""
1784        return self._labels[:]
1785
1786    def set_labels(self, labels):
1787        """Set the list of labels on the message."""
1788        self._labels = list(labels)
1789
1790    def add_label(self, label):
1791        """Add label to list of labels on the message."""
1792        if isinstance(label, str):
1793            if label not in self._labels:
1794                self._labels.append(label)
1795        else:
1796            raise TypeError('label must be a string: %s' % type(label))
1797
1798    def remove_label(self, label):
1799        """Remove label from the list of labels on the message."""
1800        try:
1801            self._labels.remove(label)
1802        except ValueError:
1803            pass
1804
1805    def get_visible(self):
1806        """Return a Message representation of visible headers."""
1807        return Message(self._visible)
1808
1809    def set_visible(self, visible):
1810        """Set the Message representation of visible headers."""
1811        self._visible = Message(visible)
1812
1813    def update_visible(self):
1814        """Update and/or sensibly generate a set of visible headers."""
1815        for header in self._visible.keys():
1816            if header in self:
1817                self._visible.replace_header(header, self[header])
1818            else:
1819                del self._visible[header]
1820        for header in ('Date', 'From', 'Reply-To', 'To', 'CC', 'Subject'):
1821            if header in self and header not in self._visible:
1822                self._visible[header] = self[header]
1823
1824    def _explain_to(self, message):
1825        """Copy Babyl-specific state to message insofar as possible."""
1826        if isinstance(message, MaildirMessage):
1827            labels = set(self.get_labels())
1828            if 'unseen' in labels:
1829                message.set_subdir('cur')
1830            else:
1831                message.set_subdir('cur')
1832                message.add_flag('S')
1833            if 'forwarded' in labels or 'resent' in labels:
1834                message.add_flag('P')
1835            if 'answered' in labels:
1836                message.add_flag('R')
1837            if 'deleted' in labels:
1838                message.add_flag('T')
1839        elif isinstance(message, _mboxMMDFMessage):
1840            labels = set(self.get_labels())
1841            if 'unseen' not in labels:
1842                message.add_flag('RO')
1843            else:
1844                message.add_flag('O')
1845            if 'deleted' in labels:
1846                message.add_flag('D')
1847            if 'answered' in labels:
1848                message.add_flag('A')
1849        elif isinstance(message, MHMessage):
1850            labels = set(self.get_labels())
1851            if 'unseen' in labels:
1852                message.add_sequence('unseen')
1853            if 'answered' in labels:
1854                message.add_sequence('replied')
1855        elif isinstance(message, BabylMessage):
1856            message.set_visible(self.get_visible())
1857            for label in self.get_labels():
1858                message.add_label(label)
1859        elif isinstance(message, Message):
1860            pass
1861        else:
1862            raise TypeError('Cannot convert to specified type: %s' %
1863                            type(message))
1864
1865
1866class MMDFMessage(_mboxMMDFMessage):
1867    """Message with MMDF-specific properties."""
1868
1869
1870class _ProxyFile:
1871    """A read-only wrapper of a file."""
1872
1873    def __init__(self, f, pos=None):
1874        """Initialize a _ProxyFile."""
1875        self._file = f
1876        if pos is None:
1877            self._pos = f.tell()
1878        else:
1879            self._pos = pos
1880
1881    def read(self, size=None):
1882        """Read bytes."""
1883        return self._read(size, self._file.read)
1884
1885    def readline(self, size=None):
1886        """Read a line."""
1887        return self._read(size, self._file.readline)
1888
1889    def readlines(self, sizehint=None):
1890        """Read multiple lines."""
1891        result = []
1892        for line in self:
1893            result.append(line)
1894            if sizehint is not None:
1895                sizehint -= len(line)
1896                if sizehint <= 0:
1897                    break
1898        return result
1899
1900    def __iter__(self):
1901        """Iterate over lines."""
1902        return iter(self.readline, "")
1903
1904    def tell(self):
1905        """Return the position."""
1906        return self._pos
1907
1908    def seek(self, offset, whence=0):
1909        """Change position."""
1910        if whence == 1:
1911            self._file.seek(self._pos)
1912        self._file.seek(offset, whence)
1913        self._pos = self._file.tell()
1914
1915    def close(self):
1916        """Close the file."""
1917        if hasattr(self, '_file'):
1918            if hasattr(self._file, 'close'):
1919                self._file.close()
1920            del self._file
1921
1922    def _read(self, size, read_method):
1923        """Read size bytes using read_method."""
1924        if size is None:
1925            size = -1
1926        self._file.seek(self._pos)
1927        result = read_method(size)
1928        self._pos = self._file.tell()
1929        return result
1930
1931
1932class _PartialFile(_ProxyFile):
1933    """A read-only wrapper of part of a file."""
1934
1935    def __init__(self, f, start=None, stop=None):
1936        """Initialize a _PartialFile."""
1937        _ProxyFile.__init__(self, f, start)
1938        self._start = start
1939        self._stop = stop
1940
1941    def tell(self):
1942        """Return the position with respect to start."""
1943        return _ProxyFile.tell(self) - self._start
1944
1945    def seek(self, offset, whence=0):
1946        """Change position, possibly with respect to start or stop."""
1947        if whence == 0:
1948            self._pos = self._start
1949            whence = 1
1950        elif whence == 2:
1951            self._pos = self._stop
1952            whence = 1
1953        _ProxyFile.seek(self, offset, whence)
1954
1955    def _read(self, size, read_method):
1956        """Read size bytes using read_method, honoring start and stop."""
1957        remaining = self._stop - self._pos
1958        if remaining <= 0:
1959            return ''
1960        if size is None or size < 0 or size > remaining:
1961            size = remaining
1962        return _ProxyFile._read(self, size, read_method)
1963
1964    def close(self):
1965        # do *not* close the underlying file object for partial files,
1966        # since it's global to the mailbox object
1967        if hasattr(self, '_file'):
1968            del self._file
1969
1970
1971def _lock_file(f, dotlock=True):
1972    """Lock file f using lockf and dot locking."""
1973    dotlock_done = False
1974    try:
1975        if fcntl:
1976            try:
1977                fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
1978            except IOError, e:
1979                if e.errno in (errno.EAGAIN, errno.EACCES, errno.EROFS):
1980                    raise ExternalClashError('lockf: lock unavailable: %s' %
1981                                             f.name)
1982                else:
1983                    raise
1984        if dotlock:
1985            try:
1986                pre_lock = _create_temporary(f.name + '.lock')
1987                pre_lock.close()
1988            except IOError, e:
1989                if e.errno in (errno.EACCES, errno.EROFS):
1990                    return  # Without write access, just skip dotlocking.
1991                else:
1992                    raise
1993            try:
1994                if hasattr(os, 'link'):
1995                    os.link(pre_lock.name, f.name + '.lock')
1996                    dotlock_done = True
1997                    os.unlink(pre_lock.name)
1998                else:
1999                    os.rename(pre_lock.name, f.name + '.lock')
2000                    dotlock_done = True
2001            except OSError, e:
2002                if e.errno == errno.EEXIST or \
2003                  (os.name == 'os2' and e.errno == errno.EACCES):
2004                    os.remove(pre_lock.name)
2005                    raise ExternalClashError('dot lock unavailable: %s' %
2006                                             f.name)
2007                else:
2008                    raise
2009    except:
2010        if fcntl:
2011            fcntl.lockf(f, fcntl.LOCK_UN)
2012        if dotlock_done:
2013            os.remove(f.name + '.lock')
2014        raise
2015
2016def _unlock_file(f):
2017    """Unlock file f using lockf and dot locking."""
2018    if fcntl:
2019        fcntl.lockf(f, fcntl.LOCK_UN)
2020    if os.path.exists(f.name + '.lock'):
2021        os.remove(f.name + '.lock')
2022
2023def _create_carefully(path):
2024    """Create a file if it doesn't exist and open for reading and writing."""
2025    fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_RDWR, 0666)
2026    try:
2027        return open(path, 'rb+')
2028    finally:
2029        os.close(fd)
2030
2031def _create_temporary(path):
2032    """Create a temp file based on path and open for reading and writing."""
2033    return _create_carefully('%s.%s.%s.%s' % (path, int(time.time()),
2034                                              socket.gethostname(),
2035                                              os.getpid()))
2036
2037def _sync_flush(f):
2038    """Ensure changes to file f are physically on disk."""
2039    f.flush()
2040    if hasattr(os, 'fsync'):
2041        os.fsync(f.fileno())
2042
2043def _sync_close(f):
2044    """Close file f, ensuring all changes are physically on disk."""
2045    _sync_flush(f)
2046    f.close()
2047
2048## Start: classes from the original module (for backward compatibility).
2049
2050# Note that the Maildir class, whose name is unchanged, itself offers a next()
2051# method for backward compatibility.
2052
2053class _Mailbox:
2054
2055    def __init__(self, fp, factory=rfc822.Message):
2056        self.fp = fp
2057        self.seekp = 0
2058        self.factory = factory
2059
2060    def __iter__(self):
2061        return iter(self.next, None)
2062
2063    def next(self):
2064        while 1:
2065            self.fp.seek(self.seekp)
2066            try:
2067                self._search_start()
2068            except EOFError:
2069                self.seekp = self.fp.tell()
2070                return None
2071            start = self.fp.tell()
2072            self._search_end()
2073            self.seekp = stop = self.fp.tell()
2074            if start != stop:
2075                break
2076        return self.factory(_PartialFile(self.fp, start, stop))
2077
2078# Recommended to use PortableUnixMailbox instead!
2079class UnixMailbox(_Mailbox):
2080
2081    def _search_start(self):
2082        while 1:
2083            pos = self.fp.tell()
2084            line = self.fp.readline()
2085            if not line:
2086                raise EOFError
2087            if line[:5] == 'From ' and self._isrealfromline(line):
2088                self.fp.seek(pos)
2089                return
2090
2091    def _search_end(self):
2092        self.fp.readline()      # Throw away header line
2093        while 1:
2094            pos = self.fp.tell()
2095            line = self.fp.readline()
2096            if not line:
2097                return
2098            if line[:5] == 'From ' and self._isrealfromline(line):
2099                self.fp.seek(pos)
2100                return
2101
2102    # An overridable mechanism to test for From-line-ness.  You can either
2103    # specify a different regular expression or define a whole new
2104    # _isrealfromline() method.  Note that this only gets called for lines
2105    # starting with the 5 characters "From ".
2106    #
2107    # BAW: According to
2108    #http://home.netscape.com/eng/mozilla/2.0/relnotes/demo/content-length.html
2109    # the only portable, reliable way to find message delimiters in a BSD (i.e
2110    # Unix mailbox) style folder is to search for "\n\nFrom .*\n", or at the
2111    # beginning of the file, "^From .*\n".  While _fromlinepattern below seems
2112    # like a good idea, in practice, there are too many variations for more
2113    # strict parsing of the line to be completely accurate.
2114    #
2115    # _strict_isrealfromline() is the old version which tries to do stricter
2116    # parsing of the From_ line.  _portable_isrealfromline() simply returns
2117    # true, since it's never called if the line doesn't already start with
2118    # "From ".
2119    #
2120    # This algorithm, and the way it interacts with _search_start() and
2121    # _search_end() may not be completely correct, because it doesn't check
2122    # that the two characters preceding "From " are \n\n or the beginning of
2123    # the file.  Fixing this would require a more extensive rewrite than is
2124    # necessary.  For convenience, we've added a PortableUnixMailbox class
2125    # which does no checking of the format of the 'From' line.
2126
2127    _fromlinepattern = (r"From \s*[^\s]+\s+\w\w\w\s+\w\w\w\s+\d?\d\s+"
2128                        r"\d?\d:\d\d(:\d\d)?(\s+[^\s]+)?\s+\d\d\d\d\s*"
2129                        r"[^\s]*\s*"
2130                        "$")
2131    _regexp = None
2132
2133    def _strict_isrealfromline(self, line):
2134        if not self._regexp:
2135            import re
2136            self._regexp = re.compile(self._fromlinepattern)
2137        return self._regexp.match(line)
2138
2139    def _portable_isrealfromline(self, line):
2140        return True
2141
2142    _isrealfromline = _strict_isrealfromline
2143
2144
2145class PortableUnixMailbox(UnixMailbox):
2146    _isrealfromline = UnixMailbox._portable_isrealfromline
2147
2148
2149class MmdfMailbox(_Mailbox):
2150
2151    def _search_start(self):
2152        while 1:
2153            line = self.fp.readline()
2154            if not line:
2155                raise EOFError
2156            if line[:5] == '\001\001\001\001\n':
2157                return
2158
2159    def _search_end(self):
2160        while 1:
2161            pos = self.fp.tell()
2162            line = self.fp.readline()
2163            if not line:
2164                return
2165            if line == '\001\001\001\001\n':
2166                self.fp.seek(pos)
2167                return
2168
2169
2170class MHMailbox:
2171
2172    def __init__(self, dirname, factory=rfc822.Message):
2173        import re
2174        pat = re.compile('^[1-9][0-9]*$')
2175        self.dirname = dirname
2176        # the three following lines could be combined into:
2177        # list = map(long, filter(pat.match, os.listdir(self.dirname)))
2178        list = os.listdir(self.dirname)
2179        list = filter(pat.match, list)
2180        list = map(long, list)
2181        list.sort()
2182        # This only works in Python 1.6 or later;
2183        # before that str() added 'L':
2184        self.boxes = map(str, list)
2185        self.boxes.reverse()
2186        self.factory = factory
2187
2188    def __iter__(self):
2189        return iter(self.next, None)
2190
2191    def next(self):
2192        if not self.boxes:
2193            return None
2194        fn = self.boxes.pop()
2195        fp = open(os.path.join(self.dirname, fn))
2196        msg = self.factory(fp)
2197        try:
2198            msg._mh_msgno = fn
2199        except (AttributeError, TypeError):
2200            pass
2201        return msg
2202
2203
2204class BabylMailbox(_Mailbox):
2205
2206    def _search_start(self):
2207        while 1:
2208            line = self.fp.readline()
2209            if not line:
2210                raise EOFError
2211            if line == '*** EOOH ***\n':
2212                return
2213
2214    def _search_end(self):
2215        while 1:
2216            pos = self.fp.tell()
2217            line = self.fp.readline()
2218            if not line:
2219                return
2220            if line == '\037\014\n' or line == '\037':
2221                self.fp.seek(pos)
2222                return
2223
2224## End: classes from the original module (for backward compatibility).
2225
2226
2227class Error(Exception):
2228    """Raised for module-specific errors."""
2229
2230class NoSuchMailboxError(Error):
2231    """The specified mailbox does not exist and won't be created."""
2232
2233class NotEmptyError(Error):
2234    """The specified mailbox is not empty and deletion was requested."""
2235
2236class ExternalClashError(Error):
2237    """Another process caused an action to fail."""
2238
2239class FormatError(Error):
2240    """A file appears to have an invalid format."""
2241