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Edit File : mailbox.py \| Size : 76.78 KB
"""Read/write support for Maildir, mbox, MH, Babyl, and MMDF mailboxes.""" # Notes for authors of new mailbox subclasses: # # Remember to fsync() changes to disk before closing a modified file # or returning from a flush() method. See functions _sync_flush() and # _sync_close(). import os import time import calendar import socket import errno import copy import warnings import email import email.message import email.generator import io import contextlib try: import fcntl except ImportError: fcntl = None __all__ = ['Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF', 'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage', 'BabylMessage', 'MMDFMessage', 'Error', 'NoSuchMailboxError', 'NotEmptyError', 'ExternalClashError', 'FormatError'] linesep = os.linesep.encode('ascii') class Mailbox: """A group of messages in a particular place.""" def __init__(self, path, factory=None, create=True): """Initialize a Mailbox instance.""" self._path = os.path.abspath(os.path.expanduser(path)) self._factory = factory def add(self, message): """Add message and return assigned key.""" raise NotImplementedError('Method must be implemented by subclass') def remove(self, key): """Remove the keyed message; raise KeyError if it doesn't exist.""" raise NotImplementedError('Method must be implemented by subclass') def __delitem__(self, key): self.remove(key) def discard(self, key): """If the keyed message exists, remove it.""" try: self.remove(key) except KeyError: pass def __setitem__(self, key, message): """Replace the keyed message; raise KeyError if it doesn't exist.""" raise NotImplementedError('Method must be implemented by subclass') def get(self, key, default=None): """Return the keyed message, or default if it doesn't exist.""" try: return self.__getitem__(key) except KeyError: return default def __getitem__(self, key): """Return the keyed message; raise KeyError if it doesn't exist.""" if not self._factory: return self.get_message(key) else: with contextlib.closing(self.get_file(key)) as file: return self._factory(file) def get_message(self, key): """Return a Message representation or raise a KeyError.""" raise NotImplementedError('Method must be implemented by subclass') def get_string(self, key): """Return a string representation or raise a KeyError. Uses email.message.Message to create a 7bit clean string representation of the message.""" return email.message_from_bytes(self.get_bytes(key)).as_string() def get_bytes(self, key): """Return a byte string representation or raise a KeyError.""" raise NotImplementedError('Method must be implemented by subclass') def get_file(self, key): """Return a file-like representation or raise a KeyError.""" raise NotImplementedError('Method must be implemented by subclass') def iterkeys(self): """Return an iterator over keys.""" raise NotImplementedError('Method must be implemented by subclass') def keys(self): """Return a list of keys.""" return list(self.iterkeys()) def itervalues(self): """Return an iterator over all messages.""" for key in self.iterkeys(): try: value = self[key] except KeyError: continue yield value def __iter__(self): return self.itervalues() def values(self): """Return a list of messages. Memory intensive.""" return list(self.itervalues()) def iteritems(self): """Return an iterator over (key, message) tuples.""" for key in self.iterkeys(): try: value = self[key] except KeyError: continue yield (key, value) def items(self): """Return a list of (key, message) tuples. Memory intensive.""" return list(self.iteritems()) def __contains__(self, key): """Return True if the keyed message exists, False otherwise.""" raise NotImplementedError('Method must be implemented by subclass') def __len__(self): """Return a count of messages in the mailbox.""" raise NotImplementedError('Method must be implemented by subclass') def clear(self): """Delete all messages.""" for key in self.keys(): self.discard(key) def pop(self, key, default=None): """Delete the keyed message and return it, or default.""" try: result = self[key] except KeyError: return default self.discard(key) return result def popitem(self): """Delete an arbitrary (key, message) pair and return it.""" for key in self.iterkeys(): return (key, self.pop(key)) # This is only run once. else: raise KeyError('No messages in mailbox') def update(self, arg=None): """Change the messages that correspond to certain keys.""" if hasattr(arg, 'iteritems'): source = arg.iteritems() elif hasattr(arg, 'items'): source = arg.items() else: source = arg bad_key = False for key, message in source: try: self[key] = message except KeyError: bad_key = True if bad_key: raise KeyError('No message with key(s)') def flush(self): """Write any pending changes to the disk.""" raise NotImplementedError('Method must be implemented by subclass') def lock(self): """Lock the mailbox.""" raise NotImplementedError('Method must be implemented by subclass') def unlock(self): """Unlock the mailbox if it is locked.""" raise NotImplementedError('Method must be implemented by subclass') def close(self): """Flush and close the mailbox.""" raise NotImplementedError('Method must be implemented by subclass') def _string_to_bytes(self, message): # If a message is not 7bit clean, we refuse to handle it since it # likely came from reading invalid messages in text mode, and that way # lies mojibake. try: return message.encode('ascii') except UnicodeError: raise ValueError("String input must be ASCII-only; " "use bytes or a Message instead") # Whether each message must end in a newline _append_newline = False def _dump_message(self, message, target, mangle_from_=False): # This assumes the target file is open in binary mode. """Dump message contents to target file.""" if isinstance(message, email.message.Message): buffer = io.BytesIO() gen = email.generator.BytesGenerator(buffer, mangle_from_, 0) gen.flatten(message) buffer.seek(0) data = buffer.read() data = data.replace(b'\n', linesep) target.write(data) if self._append_newline and not data.endswith(linesep): # Make sure the message ends with a newline target.write(linesep) elif isinstance(message, (str, bytes, io.StringIO)): if isinstance(message, io.StringIO): warnings.warn("Use of StringIO input is deprecated, " "use BytesIO instead", DeprecationWarning, 3) message = message.getvalue() if isinstance(message, str): message = self._string_to_bytes(message) if mangle_from_: message = message.replace(b'\nFrom ', b'\n>From ') message = message.replace(b'\n', linesep) target.write(message) if self._append_newline and not message.endswith(linesep): # Make sure the message ends with a newline target.write(linesep) elif hasattr(message, 'read'): if hasattr(message, 'buffer'): warnings.warn("Use of text mode files is deprecated, " "use a binary mode file instead", DeprecationWarning, 3) message = message.buffer lastline = None while True: line = message.readline() # Universal newline support. if line.endswith(b'\r\n'): line = line[:-2] + b'\n' elif line.endswith(b'\r'): line = line[:-1] + b'\n' if not line: break if mangle_from_ and line.startswith(b'From '): line = b'>From ' + line[5:] line = line.replace(b'\n', linesep) target.write(line) lastline = line if self._append_newline and lastline and not lastline.endswith(linesep): # Make sure the message ends with a newline target.write(linesep) else: raise TypeError('Invalid message type: %s' % type(message)) class Maildir(Mailbox): """A qmail-style Maildir mailbox.""" colon = ':' def __init__(self, dirname, factory=None, create=True): """Initialize a Maildir instance.""" Mailbox.__init__(self, dirname, factory, create) self._paths = { 'tmp': os.path.join(self._path, 'tmp'), 'new': os.path.join(self._path, 'new'), 'cur': os.path.join(self._path, 'cur'), } if not os.path.exists(self._path): if create: os.mkdir(self._path, 0o700) for path in self._paths.values(): os.mkdir(path, 0o700) else: raise NoSuchMailboxError(self._path) self._toc = {} self._toc_mtimes = {'cur': 0, 'new': 0} self._last_read = 0 # Records last time we read cur/new self._skewfactor = 0.1 # Adjust if os/fs clocks are skewing def add(self, message): """Add message and return assigned key.""" tmp_file = self._create_tmp() try: self._dump_message(message, tmp_file) except BaseException: tmp_file.close() os.remove(tmp_file.name) raise _sync_close(tmp_file) if isinstance(message, MaildirMessage): subdir = message.get_subdir() suffix = self.colon + message.get_info() if suffix == self.colon: suffix = '' else: subdir = 'new' suffix = '' uniq = os.path.basename(tmp_file.name).split(self.colon)[0] dest = os.path.join(self._path, subdir, uniq + suffix) if isinstance(message, MaildirMessage): os.utime(tmp_file.name, (os.path.getatime(tmp_file.name), message.get_date())) # No file modification should be done after the file is moved to its # final position in order to prevent race conditions with changes # from other programs try: try: os.link(tmp_file.name, dest) except (AttributeError, PermissionError): os.rename(tmp_file.name, dest) else: os.remove(tmp_file.name) except OSError as e: os.remove(tmp_file.name) if e.errno == errno.EEXIST: raise ExternalClashError('Name clash with existing message: %s' % dest) else: raise return uniq def remove(self, key): """Remove the keyed message; raise KeyError if it doesn't exist.""" os.remove(os.path.join(self._path, self._lookup(key))) def discard(self, key): """If the keyed message exists, remove it.""" # This overrides an inapplicable implementation in the superclass. try: self.remove(key) except (KeyError, FileNotFoundError): pass def __setitem__(self, key, message): """Replace the keyed message; raise KeyError if it doesn't exist.""" old_subpath = self._lookup(key) temp_key = self.add(message) temp_subpath = self._lookup(temp_key) if isinstance(message, MaildirMessage): # temp's subdir and suffix were specified by message. dominant_subpath = temp_subpath else: # temp's subdir and suffix were defaults from add(). dominant_subpath = old_subpath subdir = os.path.dirname(dominant_subpath) if self.colon in dominant_subpath: suffix = self.colon + dominant_subpath.split(self.colon)[-1] else: suffix = '' self.discard(key) tmp_path = os.path.join(self._path, temp_subpath) new_path = os.path.join(self._path, subdir, key + suffix) if isinstance(message, MaildirMessage): os.utime(tmp_path, (os.path.getatime(tmp_path), message.get_date())) # No file modification should be done after the file is moved to its # final position in order to prevent race conditions with changes # from other programs os.rename(tmp_path, new_path) def get_message(self, key): """Return a Message representation or raise a KeyError.""" subpath = self._lookup(key) with open(os.path.join(self._path, subpath), 'rb') as f: if self._factory: msg = self._factory(f) else: msg = MaildirMessage(f) subdir, name = os.path.split(subpath) msg.set_subdir(subdir) if self.colon in name: msg.set_info(name.split(self.colon)[-1]) msg.set_date(os.path.getmtime(os.path.join(self._path, subpath))) return msg def get_bytes(self, key): """Return a bytes representation or raise a KeyError.""" with open(os.path.join(self._path, self._lookup(key)), 'rb') as f: return f.read().replace(linesep, b'\n') def get_file(self, key): """Return a file-like representation or raise a KeyError.""" f = open(os.path.join(self._path, self._lookup(key)), 'rb') return _ProxyFile(f) def iterkeys(self): """Return an iterator over keys.""" self._refresh() for key in self._toc: try: self._lookup(key) except KeyError: continue yield key def __contains__(self, key): """Return True if the keyed message exists, False otherwise.""" self._refresh() return key in self._toc def __len__(self): """Return a count of messages in the mailbox.""" self._refresh() return len(self._toc) def flush(self): """Write any pending changes to disk.""" # Maildir changes are always written immediately, so there's nothing # to do. pass def lock(self): """Lock the mailbox.""" return def unlock(self): """Unlock the mailbox if it is locked.""" return def close(self): """Flush and close the mailbox.""" return def list_folders(self): """Return a list of folder names.""" result = [] for entry in os.listdir(self._path): if len(entry) > 1 and entry[0] == '.' and \ os.path.isdir(os.path.join(self._path, entry)): result.append(entry[1:]) return result def get_folder(self, folder): """Return a Maildir instance for the named folder.""" return Maildir(os.path.join(self._path, '.' + folder), factory=self._factory, create=False) def add_folder(self, folder): """Create a folder and return a Maildir instance representing it.""" path = os.path.join(self._path, '.' + folder) result = Maildir(path, factory=self._factory) maildirfolder_path = os.path.join(path, 'maildirfolder') if not os.path.exists(maildirfolder_path): os.close(os.open(maildirfolder_path, os.O_CREAT \| os.O_WRONLY, 0o666)) return result def remove_folder(self, folder): """Delete the named folder, which must be empty.""" path = os.path.join(self._path, '.' + folder) for entry in os.listdir(os.path.join(path, 'new')) + \ os.listdir(os.path.join(path, 'cur')): if len(entry) < 1 or entry[0] != '.': raise NotEmptyError('Folder contains message(s): %s' % folder) for entry in os.listdir(path): if entry != 'new' and entry != 'cur' and entry != 'tmp' and \ os.path.isdir(os.path.join(path, entry)): raise NotEmptyError("Folder contains subdirectory '%s': %s" % (folder, entry)) for root, dirs, files in os.walk(path, topdown=False): for entry in files: os.remove(os.path.join(root, entry)) for entry in dirs: os.rmdir(os.path.join(root, entry)) os.rmdir(path) def clean(self): """Delete old files in "tmp".""" now = time.time() for entry in os.listdir(os.path.join(self._path, 'tmp')): path = os.path.join(self._path, 'tmp', entry) if now - os.path.getatime(path) > 129600: # 60 * 60 * 36 os.remove(path) _count = 1 # This is used to generate unique file names. def _create_tmp(self): """Create a file in the tmp subdirectory and open and return it.""" now = time.time() hostname = socket.gethostname() if '/' in hostname: hostname = hostname.replace('/', r'\057') if ':' in hostname: hostname = hostname.replace(':', r'\072') uniq = "%s.M%sP%sQ%s.%s" % (int(now), int(now % 1 * 1e6), os.getpid(), Maildir._count, hostname) path = os.path.join(self._path, 'tmp', uniq) try: os.stat(path) except FileNotFoundError: Maildir._count += 1 try: return _create_carefully(path) except FileExistsError: pass # Fall through to here if stat succeeded or open raised EEXIST. raise ExternalClashError('Name clash prevented file creation: %s' % path) def _refresh(self): """Update table of contents mapping.""" # If it has been less than two seconds since the last _refresh() call, # we have to unconditionally re-read the mailbox just in case it has # been modified, because os.path.mtime() has a 2 sec resolution in the # most common worst case (FAT) and a 1 sec resolution typically. This # results in a few unnecessary re-reads when _refresh() is called # multiple times in that interval, but once the clock ticks over, we # will only re-read as needed. Because the filesystem might be being # served by an independent system with its own clock, we record and # compare with the mtimes from the filesystem. Because the other # system's clock might be skewing relative to our clock, we add an # extra delta to our wait. The default is one tenth second, but is an # instance variable and so can be adjusted if dealing with a # particularly skewed or irregular system. if time.time() - self._last_read > 2 + self._skewfactor: refresh = False for subdir in self._toc_mtimes: mtime = os.path.getmtime(self._paths[subdir]) if mtime > self._toc_mtimes[subdir]: refresh = True self._toc_mtimes[subdir] = mtime if not refresh: return # Refresh toc self._toc = {} for subdir in self._toc_mtimes: path = self._paths[subdir] for entry in os.listdir(path): p = os.path.join(path, entry) if os.path.isdir(p): continue uniq = entry.split(self.colon)[0] self._toc[uniq] = os.path.join(subdir, entry) self._last_read = time.time() def _lookup(self, key): """Use TOC to return subpath for given key, or raise a KeyError.""" try: if os.path.exists(os.path.join(self._path, self._toc[key])): return self._toc[key] except KeyError: pass self._refresh() try: return self._toc[key] except KeyError: raise KeyError('No message with key: %s' % key) # This method is for backward compatibility only. def next(self): """Return the next message in a one-time iteration.""" if not hasattr(self, '_onetime_keys'): self._onetime_keys = self.iterkeys() while True: try: return self[next(self._onetime_keys)] except StopIteration: return None except KeyError: continue class _singlefileMailbox(Mailbox): """A single-file mailbox.""" def __init__(self, path, factory=None, create=True): """Initialize a single-file mailbox.""" Mailbox.__init__(self, path, factory, create) try: f = open(self._path, 'rb+') except OSError as e: if e.errno == errno.ENOENT: if create: f = open(self._path, 'wb+') else: raise NoSuchMailboxError(self._path) elif e.errno in (errno.EACCES, errno.EROFS): f = open(self._path, 'rb') else: raise self._file = f self._toc = None self._next_key = 0 self._pending = False # No changes require rewriting the file. self._pending_sync = False # No need to sync the file self._locked = False self._file_length = None # Used to record mailbox size def add(self, message): """Add message and return assigned key.""" self._lookup() self._toc[self._next_key] = self._append_message(message) self._next_key += 1 # _append_message appends the message to the mailbox file. We # don't need a full rewrite + rename, sync is enough. self._pending_sync = True return self._next_key - 1 def remove(self, key): """Remove the keyed message; raise KeyError if it doesn't exist.""" self._lookup(key) del self._toc[key] self._pending = True def __setitem__(self, key, message): """Replace the keyed message; raise KeyError if it doesn't exist.""" self._lookup(key) self._toc[key] = self._append_message(message) self._pending = True def iterkeys(self): """Return an iterator over keys.""" self._lookup() yield from self._toc.keys() def __contains__(self, key): """Return True if the keyed message exists, False otherwise.""" self._lookup() return key in self._toc def __len__(self): """Return a count of messages in the mailbox.""" self._lookup() return len(self._toc) def lock(self): """Lock the mailbox.""" if not self._locked: _lock_file(self._file) self._locked = True def unlock(self): """Unlock the mailbox if it is locked.""" if self._locked: _unlock_file(self._file) self._locked = False def flush(self): """Write any pending changes to disk.""" if not self._pending: if self._pending_sync: # Messages have only been added, so syncing the file # is enough. _sync_flush(self._file) self._pending_sync = False return # In order to be writing anything out at all, self._toc must # already have been generated (and presumably has been modified # by adding or deleting an item). assert self._toc is not None # Check length of self._file; if it's changed, some other process # has modified the mailbox since we scanned it. self._file.seek(0, 2) cur_len = self._file.tell() if cur_len != self._file_length: raise ExternalClashError('Size of mailbox file changed ' '(expected %i, found %i)' % (self._file_length, cur_len)) new_file = _create_temporary(self._path) try: new_toc = {} self._pre_mailbox_hook(new_file) for key in sorted(self._toc.keys()): start, stop = self._toc[key] self._file.seek(start) self._pre_message_hook(new_file) new_start = new_file.tell() while True: buffer = self._file.read(min(4096, stop - self._file.tell())) if not buffer: break new_file.write(buffer) new_toc[key] = (new_start, new_file.tell()) self._post_message_hook(new_file) self._file_length = new_file.tell() except: new_file.close() os.remove(new_file.name) raise _sync_close(new_file) # self._file is about to get replaced, so no need to sync. self._file.close() # Make sure the new file's mode is the same as the old file's mode = os.stat(self._path).st_mode os.chmod(new_file.name, mode) try: os.rename(new_file.name, self._path) except FileExistsError: os.remove(self._path) os.rename(new_file.name, self._path) self._file = open(self._path, 'rb+') self._toc = new_toc self._pending = False self._pending_sync = False if self._locked: _lock_file(self._file, dotlock=False) def _pre_mailbox_hook(self, f): """Called before writing the mailbox to file f.""" return def _pre_message_hook(self, f): """Called before writing each message to file f.""" return def _post_message_hook(self, f): """Called after writing each message to file f.""" return def close(self): """Flush and close the mailbox.""" try: self.flush() finally: try: if self._locked: self.unlock() finally: self._file.close() # Sync has been done by self.flush() above. def _lookup(self, key=None): """Return (start, stop) or raise KeyError.""" if self._toc is None: self._generate_toc() if key is not None: try: return self._toc[key] except KeyError: raise KeyError('No message with key: %s' % key) def _append_message(self, message): """Append message to mailbox and return (start, stop) offsets.""" self._file.seek(0, 2) before = self._file.tell() if len(self._toc) == 0 and not self._pending: # This is the first message, and the _pre_mailbox_hook # hasn't yet been called. If self._pending is True, # messages have been removed, so _pre_mailbox_hook must # have been called already. self._pre_mailbox_hook(self._file) try: self._pre_message_hook(self._file) offsets = self._install_message(message) self._post_message_hook(self._file) except BaseException: self._file.truncate(before) raise self._file.flush() self._file_length = self._file.tell() # Record current length of mailbox return offsets class _mboxMMDF(_singlefileMailbox): """An mbox or MMDF mailbox.""" _mangle_from_ = True def get_message(self, key): """Return a Message representation or raise a KeyError.""" start, stop = self._lookup(key) self._file.seek(start) from_line = self._file.readline().replace(linesep, b'') string = self._file.read(stop - self._file.tell()) msg = self._message_factory(string.replace(linesep, b'\n')) msg.set_from(from_line[5:].decode('ascii')) return msg def get_string(self, key, from_=False): """Return a string representation or raise a KeyError.""" return email.message_from_bytes( self.get_bytes(key)).as_string(unixfrom=from_) def get_bytes(self, key, from_=False): """Return a string representation or raise a KeyError.""" start, stop = self._lookup(key) self._file.seek(start) if not from_: self._file.readline() string = self._file.read(stop - self._file.tell()) return string.replace(linesep, b'\n') def get_file(self, key, from_=False): """Return a file-like representation or raise a KeyError.""" start, stop = self._lookup(key) self._file.seek(start) if not from_: self._file.readline() return _PartialFile(self._file, self._file.tell(), stop) def _install_message(self, message): """Format a message and blindly write to self._file.""" from_line = None if isinstance(message, str): message = self._string_to_bytes(message) if isinstance(message, bytes) and message.startswith(b'From '): newline = message.find(b'\n') if newline != -1: from_line = message[:newline] message = message[newline + 1:] else: from_line = message message = b'' elif isinstance(message, _mboxMMDFMessage): author = message.get_from().encode('ascii') from_line = b'From ' + author elif isinstance(message, email.message.Message): from_line = message.get_unixfrom() # May be None. if from_line is not None: from_line = from_line.encode('ascii') if from_line is None: from_line = b'From MAILER-DAEMON ' + time.asctime(time.gmtime()).encode() start = self._file.tell() self._file.write(from_line + linesep) self._dump_message(message, self._file, self._mangle_from_) stop = self._file.tell() return (start, stop) class mbox(_mboxMMDF): """A classic mbox mailbox.""" _mangle_from_ = True # All messages must end in a newline character, and # _post_message_hooks outputs an empty line between messages. _append_newline = True def __init__(self, path, factory=None, create=True): """Initialize an mbox mailbox.""" self._message_factory = mboxMessage _mboxMMDF.__init__(self, path, factory, create) def _post_message_hook(self, f): """Called after writing each message to file f.""" f.write(linesep) def _generate_toc(self): """Generate key-to-(start, stop) table of contents.""" starts, stops = [], [] last_was_empty = False self._file.seek(0) while True: line_pos = self._file.tell() line = self._file.readline() if line.startswith(b'From '): if len(stops) < len(starts): if last_was_empty: stops.append(line_pos - len(linesep)) else: # The last line before the "From " line wasn't # blank, but we consider it a start of a # message anyway. stops.append(line_pos) starts.append(line_pos) last_was_empty = False elif not line: if last_was_empty: stops.append(line_pos - len(linesep)) else: stops.append(line_pos) break elif line == linesep: last_was_empty = True else: last_was_empty = False self._toc = dict(enumerate(zip(starts, stops))) self._next_key = len(self._toc) self._file_length = self._file.tell() class MMDF(_mboxMMDF): """An MMDF mailbox.""" def __init__(self, path, factory=None, create=True): """Initialize an MMDF mailbox.""" self._message_factory = MMDFMessage _mboxMMDF.__init__(self, path, factory, create) def _pre_message_hook(self, f): """Called before writing each message to file f.""" f.write(b'\001\001\001\001' + linesep) def _post_message_hook(self, f): """Called after writing each message to file f.""" f.write(linesep + b'\001\001\001\001' + linesep) def _generate_toc(self): """Generate key-to-(start, stop) table of contents.""" starts, stops = [], [] self._file.seek(0) next_pos = 0 while True: line_pos = next_pos line = self._file.readline() next_pos = self._file.tell() if line.startswith(b'\001\001\001\001' + linesep): starts.append(next_pos) while True: line_pos = next_pos line = self._file.readline() next_pos = self._file.tell() if line == b'\001\001\001\001' + linesep: stops.append(line_pos - len(linesep)) break elif not line: stops.append(line_pos) break elif not line: break self._toc = dict(enumerate(zip(starts, stops))) self._next_key = len(self._toc) self._file.seek(0, 2) self._file_length = self._file.tell() class MH(Mailbox): """An MH mailbox.""" def __init__(self, path, factory=None, create=True): """Initialize an MH instance.""" Mailbox.__init__(self, path, factory, create) if not os.path.exists(self._path): if create: os.mkdir(self._path, 0o700) os.close(os.open(os.path.join(self._path, '.mh_sequences'), os.O_CREAT \| os.O_EXCL \| os.O_WRONLY, 0o600)) else: raise NoSuchMailboxError(self._path) self._locked = False def add(self, message): """Add message and return assigned key.""" keys = self.keys() if len(keys) == 0: new_key = 1 else: new_key = max(keys) + 1 new_path = os.path.join(self._path, str(new_key)) f = _create_carefully(new_path) closed = False try: if self._locked: _lock_file(f) try: try: self._dump_message(message, f) except BaseException: # Unlock and close so it can be deleted on Windows if self._locked: _unlock_file(f) _sync_close(f) closed = True os.remove(new_path) raise if isinstance(message, MHMessage): self._dump_sequences(message, new_key) finally: if self._locked: _unlock_file(f) finally: if not closed: _sync_close(f) return new_key def remove(self, key): """Remove the keyed message; raise KeyError if it doesn't exist.""" path = os.path.join(self._path, str(key)) try: f = open(path, 'rb+') except OSError as e: if e.errno == errno.ENOENT: raise KeyError('No message with key: %s' % key) else: raise else: f.close() os.remove(path) def __setitem__(self, key, message): """Replace the keyed message; raise KeyError if it doesn't exist.""" path = os.path.join(self._path, str(key)) try: f = open(path, 'rb+') except OSError as e: if e.errno == errno.ENOENT: raise KeyError('No message with key: %s' % key) else: raise try: if self._locked: _lock_file(f) try: os.close(os.open(path, os.O_WRONLY \| os.O_TRUNC)) self._dump_message(message, f) if isinstance(message, MHMessage): self._dump_sequences(message, key) finally: if self._locked: _unlock_file(f) finally: _sync_close(f) def get_message(self, key): """Return a Message representation or raise a KeyError.""" try: if self._locked: f = open(os.path.join(self._path, str(key)), 'rb+') else: f = open(os.path.join(self._path, str(key)), 'rb') except OSError as e: if e.errno == errno.ENOENT: raise KeyError('No message with key: %s' % key) else: raise with f: if self._locked: _lock_file(f) try: msg = MHMessage(f) finally: if self._locked: _unlock_file(f) for name, key_list in self.get_sequences().items(): if key in key_list: msg.add_sequence(name) return msg def get_bytes(self, key): """Return a bytes representation or raise a KeyError.""" try: if self._locked: f = open(os.path.join(self._path, str(key)), 'rb+') else: f = open(os.path.join(self._path, str(key)), 'rb') except OSError as e: if e.errno == errno.ENOENT: raise KeyError('No message with key: %s' % key) else: raise with f: if self._locked: _lock_file(f) try: return f.read().replace(linesep, b'\n') finally: if self._locked: _unlock_file(f) def get_file(self, key): """Return a file-like representation or raise a KeyError.""" try: f = open(os.path.join(self._path, str(key)), 'rb') except OSError as e: if e.errno == errno.ENOENT: raise KeyError('No message with key: %s' % key) else: raise return _ProxyFile(f) def iterkeys(self): """Return an iterator over keys.""" return iter(sorted(int(entry) for entry in os.listdir(self._path) if entry.isdigit())) def __contains__(self, key): """Return True if the keyed message exists, False otherwise.""" return os.path.exists(os.path.join(self._path, str(key))) def __len__(self): """Return a count of messages in the mailbox.""" return len(list(self.iterkeys())) def lock(self): """Lock the mailbox.""" if not self._locked: self._file = open(os.path.join(self._path, '.mh_sequences'), 'rb+') _lock_file(self._file) self._locked = True def unlock(self): """Unlock the mailbox if it is locked.""" if self._locked: _unlock_file(self._file) _sync_close(self._file) del self._file self._locked = False def flush(self): """Write any pending changes to the disk.""" return def close(self): """Flush and close the mailbox.""" if self._locked: self.unlock() def list_folders(self): """Return a list of folder names.""" result = [] for entry in os.listdir(self._path): if os.path.isdir(os.path.join(self._path, entry)): result.append(entry) return result def get_folder(self, folder): """Return an MH instance for the named folder.""" return MH(os.path.join(self._path, folder), factory=self._factory, create=False) def add_folder(self, folder): """Create a folder and return an MH instance representing it.""" return MH(os.path.join(self._path, folder), factory=self._factory) def remove_folder(self, folder): """Delete the named folder, which must be empty.""" path = os.path.join(self._path, folder) entries = os.listdir(path) if entries == ['.mh_sequences']: os.remove(os.path.join(path, '.mh_sequences')) elif entries == []: pass else: raise NotEmptyError('Folder not empty: %s' % self._path) os.rmdir(path) def get_sequences(self): """Return a name-to-key-list dictionary to define each sequence.""" results = {} with open(os.path.join(self._path, '.mh_sequences'), 'r', encoding='ASCII') as f: all_keys = set(self.keys()) for line in f: try: name, contents = line.split(':') keys = set() for spec in contents.split(): if spec.isdigit(): keys.add(int(spec)) else: start, stop = (int(x) for x in spec.split('-')) keys.update(range(start, stop + 1)) results[name] = [key for key in sorted(keys) \ if key in all_keys] if len(results[name]) == 0: del results[name] except ValueError: raise FormatError('Invalid sequence specification: %s' % line.rstrip()) return results def set_sequences(self, sequences): """Set sequences using the given name-to-key-list dictionary.""" f = open(os.path.join(self._path, '.mh_sequences'), 'r+', encoding='ASCII') try: os.close(os.open(f.name, os.O_WRONLY \| os.O_TRUNC)) for name, keys in sequences.items(): if len(keys) == 0: continue f.write(name + ':') prev = None completing = False for key in sorted(set(keys)): if key - 1 == prev: if not completing: completing = True f.write('-') elif completing: completing = False f.write('%s %s' % (prev, key)) else: f.write(' %s' % key) prev = key if completing: f.write(str(prev) + '\n') else: f.write('\n') finally: _sync_close(f) def pack(self): """Re-name messages to eliminate numbering gaps. Invalidates keys.""" sequences = self.get_sequences() prev = 0 changes = [] for key in self.iterkeys(): if key - 1 != prev: changes.append((key, prev + 1)) try: os.link(os.path.join(self._path, str(key)), os.path.join(self._path, str(prev + 1))) except (AttributeError, PermissionError): os.rename(os.path.join(self._path, str(key)), os.path.join(self._path, str(prev + 1))) else: os.unlink(os.path.join(self._path, str(key))) prev += 1 self._next_key = prev + 1 if len(changes) == 0: return for name, key_list in sequences.items(): for old, new in changes: if old in key_list: key_list[key_list.index(old)] = new self.set_sequences(sequences) def _dump_sequences(self, message, key): """Inspect a new MHMessage and update sequences appropriately.""" pending_sequences = message.get_sequences() all_sequences = self.get_sequences() for name, key_list in all_sequences.items(): if name in pending_sequences: key_list.append(key) elif key in key_list: del key_list[key_list.index(key)] for sequence in pending_sequences: if sequence not in all_sequences: all_sequences[sequence] = [key] self.set_sequences(all_sequences) class Babyl(_singlefileMailbox): """An Rmail-style Babyl mailbox.""" _special_labels = frozenset({'unseen', 'deleted', 'filed', 'answered', 'forwarded', 'edited', 'resent'}) def __init__(self, path, factory=None, create=True): """Initialize a Babyl mailbox.""" _singlefileMailbox.__init__(self, path, factory, create) self._labels = {} def add(self, message): """Add message and return assigned key.""" key = _singlefileMailbox.add(self, message) if isinstance(message, BabylMessage): self._labels[key] = message.get_labels() return key def remove(self, key): """Remove the keyed message; raise KeyError if it doesn't exist.""" _singlefileMailbox.remove(self, key) if key in self._labels: del self._labels[key] def __setitem__(self, key, message): """Replace the keyed message; raise KeyError if it doesn't exist.""" _singlefileMailbox.__setitem__(self, key, message) if isinstance(message, BabylMessage): self._labels[key] = message.get_labels() def get_message(self, key): """Return a Message representation or raise a KeyError.""" start, stop = self._lookup(key) self._file.seek(start) self._file.readline() # Skip b'1,' line specifying labels. original_headers = io.BytesIO() while True: line = self._file.readline() if line == b'* EOOH ' + linesep or not line: break original_headers.write(line.replace(linesep, b'\n')) visible_headers = io.BytesIO() while True: line = self._file.readline() if line == linesep or not line: break visible_headers.write(line.replace(linesep, b'\n')) # Read up to the stop, or to the end n = stop - self._file.tell() assert n >= 0 body = self._file.read(n) body = body.replace(linesep, b'\n') msg = BabylMessage(original_headers.getvalue() + body) msg.set_visible(visible_headers.getvalue()) if key in self._labels: msg.set_labels(self._labels[key]) return msg def get_bytes(self, key): """Return a string representation or raise a KeyError.""" start, stop = self._lookup(key) self._file.seek(start) self._file.readline() # Skip b'1,' line specifying labels. original_headers = io.BytesIO() while True: line = self._file.readline() if line == b' EOOH ' + linesep or not line: break original_headers.write(line.replace(linesep, b'\n')) while True: line = self._file.readline() if line == linesep or not line: break headers = original_headers.getvalue() n = stop - self._file.tell() assert n >= 0 data = self._file.read(n) data = data.replace(linesep, b'\n') return headers + data def get_file(self, key): """Return a file-like representation or raise a KeyError.""" return io.BytesIO(self.get_bytes(key).replace(b'\n', linesep)) def get_labels(self): """Return a list of user-defined labels in the mailbox.""" self._lookup() labels = set() for label_list in self._labels.values(): labels.update(label_list) labels.difference_update(self._special_labels) return list(labels) def _generate_toc(self): """Generate key-to-(start, stop) table of contents.""" starts, stops = [], [] self._file.seek(0) next_pos = 0 label_lists = [] while True: line_pos = next_pos line = self._file.readline() next_pos = self._file.tell() if line == b'\037\014' + linesep: if len(stops) < len(starts): stops.append(line_pos - len(linesep)) starts.append(next_pos) labels = [label.strip() for label in self._file.readline()[1:].split(b',') if label.strip()] label_lists.append(labels) elif line == b'\037' or line == b'\037' + linesep: if len(stops) < len(starts): stops.append(line_pos - len(linesep)) elif not line: stops.append(line_pos - len(linesep)) break self._toc = dict(enumerate(zip(starts, stops))) self._labels = dict(enumerate(label_lists)) self._next_key = len(self._toc) self._file.seek(0, 2) self._file_length = self._file.tell() def _pre_mailbox_hook(self, f): """Called before writing the mailbox to file f.""" babyl = b'BABYL OPTIONS:' + linesep babyl += b'Version: 5' + linesep labels = self.get_labels() labels = (label.encode() for label in labels) babyl += b'Labels:' + b','.join(labels) + linesep babyl += b'\037' f.write(babyl) def _pre_message_hook(self, f): """Called before writing each message to file f.""" f.write(b'\014' + linesep) def _post_message_hook(self, f): """Called after writing each message to file f.""" f.write(linesep + b'\037') def _install_message(self, message): """Write message contents and return (start, stop).""" start = self._file.tell() if isinstance(message, BabylMessage): special_labels = [] labels = [] for label in message.get_labels(): if label in self._special_labels: special_labels.append(label) else: labels.append(label) self._file.write(b'1') for label in special_labels: self._file.write(b', ' + label.encode()) self._file.write(b',,') for label in labels: self._file.write(b' ' + label.encode() + b',') self._file.write(linesep) else: self._file.write(b'1,,' + linesep) if isinstance(message, email.message.Message): orig_buffer = io.BytesIO() orig_generator = email.generator.BytesGenerator(orig_buffer, False, 0) orig_generator.flatten(message) orig_buffer.seek(0) while True: line = orig_buffer.readline() self._file.write(line.replace(b'\n', linesep)) if line == b'\n' or not line: break self._file.write(b' EOOH ' + linesep) if isinstance(message, BabylMessage): vis_buffer = io.BytesIO() vis_generator = email.generator.BytesGenerator(vis_buffer, False, 0) vis_generator.flatten(message.get_visible()) while True: line = vis_buffer.readline() self._file.write(line.replace(b'\n', linesep)) if line == b'\n' or not line: break else: orig_buffer.seek(0) while True: line = orig_buffer.readline() self._file.write(line.replace(b'\n', linesep)) if line == b'\n' or not line: break while True: buffer = orig_buffer.read(4096) # Buffer size is arbitrary. if not buffer: break self._file.write(buffer.replace(b'\n', linesep)) elif isinstance(message, (bytes, str, io.StringIO)): if isinstance(message, io.StringIO): warnings.warn("Use of StringIO input is deprecated, " "use BytesIO instead", DeprecationWarning, 3) message = message.getvalue() if isinstance(message, str): message = self._string_to_bytes(message) body_start = message.find(b'\n\n') + 2 if body_start - 2 != -1: self._file.write(message[:body_start].replace(b'\n', linesep)) self._file.write(b' EOOH ' + linesep) self._file.write(message[:body_start].replace(b'\n', linesep)) self._file.write(message[body_start:].replace(b'\n', linesep)) else: self._file.write(b' EOOH ' + linesep + linesep) self._file.write(message.replace(b'\n', linesep)) elif hasattr(message, 'readline'): if hasattr(message, 'buffer'): warnings.warn("Use of text mode files is deprecated, " "use a binary mode file instead", DeprecationWarning, 3) message = message.buffer original_pos = message.tell() first_pass = True while True: line = message.readline() # Universal newline support. if line.endswith(b'\r\n'): line = line[:-2] + b'\n' elif line.endswith(b'\r'): line = line[:-1] + b'\n' self._file.write(line.replace(b'\n', linesep)) if line == b'\n' or not line: if first_pass: first_pass = False self._file.write(b' EOOH ' + linesep) message.seek(original_pos) else: break while True: line = message.readline() if not line: break # Universal newline support. if line.endswith(b'\r\n'): line = line[:-2] + linesep elif line.endswith(b'\r'): line = line[:-1] + linesep elif line.endswith(b'\n'): line = line[:-1] + linesep self._file.write(line) else: raise TypeError('Invalid message type: %s' % type(message)) stop = self._file.tell() return (start, stop) class Message(email.message.Message): """Message with mailbox-format-specific properties.""" def __init__(self, message=None): """Initialize a Message instance.""" if isinstance(message, email.message.Message): self._become_message(copy.deepcopy(message)) if isinstance(message, Message): message._explain_to(self) elif isinstance(message, bytes): self._become_message(email.message_from_bytes(message)) elif isinstance(message, str): self._become_message(email.message_from_string(message)) elif isinstance(message, io.TextIOWrapper): self._become_message(email.message_from_file(message)) elif hasattr(message, "read"): self._become_message(email.message_from_binary_file(message)) elif message is None: email.message.Message.__init__(self) else: raise TypeError('Invalid message type: %s' % type(message)) def _become_message(self, message): """Assume the non-format-specific state of message.""" type_specific = getattr(message, '_type_specific_attributes', []) for name in message.__dict__: if name not in type_specific: self.__dict__[name] = message.__dict__[name] def _explain_to(self, message): """Copy format-specific state to message insofar as possible.""" if isinstance(message, Message): return # There's nothing format-specific to explain. else: raise TypeError('Cannot convert to specified type') class MaildirMessage(Message): """Message with Maildir-specific properties.""" _type_specific_attributes = ['_subdir', '_info', '_date'] def __init__(self, message=None): """Initialize a MaildirMessage instance.""" self._subdir = 'new' self._info = '' self._date = time.time() Message.__init__(self, message) def get_subdir(self): """Return 'new' or 'cur'.""" return self._subdir def set_subdir(self, subdir): """Set subdir to 'new' or 'cur'.""" if subdir == 'new' or subdir == 'cur': self._subdir = subdir else: raise ValueError("subdir must be 'new' or 'cur': %s" % subdir) def get_flags(self): """Return as a string the flags that are set.""" if self._info.startswith('2,'): return self._info[2:] else: return '' def set_flags(self, flags): """Set the given flags and unset all others.""" self._info = '2,' + ''.join(sorted(flags)) def add_flag(self, flag): """Set the given flag(s) without changing others.""" self.set_flags(''.join(set(self.get_flags()) \| set(flag))) def remove_flag(self, flag): """Unset the given string flag(s) without changing others.""" if self.get_flags(): self.set_flags(''.join(set(self.get_flags()) - set(flag))) def get_date(self): """Return delivery date of message, in seconds since the epoch.""" return self._date def set_date(self, date): """Set delivery date of message, in seconds since the epoch.""" try: self._date = float(date) except ValueError: raise TypeError("can't convert to float: %s" % date) def get_info(self): """Get the message's "info" as a string.""" return self._info def set_info(self, info): """Set the message's "info" string.""" if isinstance(info, str): self._info = info else: raise TypeError('info must be a string: %s' % type(info)) def _explain_to(self, message): """Copy Maildir-specific state to message insofar as possible.""" if isinstance(message, MaildirMessage): message.set_flags(self.get_flags()) message.set_subdir(self.get_subdir()) message.set_date(self.get_date()) elif isinstance(message, _mboxMMDFMessage): flags = set(self.get_flags()) if 'S' in flags: message.add_flag('R') if self.get_subdir() == 'cur': message.add_flag('O') if 'T' in flags: message.add_flag('D') if 'F' in flags: message.add_flag('F') if 'R' in flags: message.add_flag('A') message.set_from('MAILER-DAEMON', time.gmtime(self.get_date())) elif isinstance(message, MHMessage): flags = set(self.get_flags()) if 'S' not in flags: message.add_sequence('unseen') if 'R' in flags: message.add_sequence('replied') if 'F' in flags: message.add_sequence('flagged') elif isinstance(message, BabylMessage): flags = set(self.get_flags()) if 'S' not in flags: message.add_label('unseen') if 'T' in flags: message.add_label('deleted') if 'R' in flags: message.add_label('answered') if 'P' in flags: message.add_label('forwarded') elif isinstance(message, Message): pass else: raise TypeError('Cannot convert to specified type: %s' % type(message)) class _mboxMMDFMessage(Message): """Message with mbox- or MMDF-specific properties.""" _type_specific_attributes = ['_from'] def __init__(self, message=None): """Initialize an mboxMMDFMessage instance.""" self.set_from('MAILER-DAEMON', True) if isinstance(message, email.message.Message): unixfrom = message.get_unixfrom() if unixfrom is not None and unixfrom.startswith('From '): self.set_from(unixfrom[5:]) Message.__init__(self, message) def get_from(self): """Return contents of "From " line.""" return self._from def set_from(self, from_, time_=None): """Set "From " line, formatting and appending time_ if specified.""" if time_ is not None: if time_ is True: time_ = time.gmtime() from_ += ' ' + time.asctime(time_) self._from = from_ def get_flags(self): """Return as a string the flags that are set.""" return self.get('Status', '') + self.get('X-Status', '') def set_flags(self, flags): """Set the given flags and unset all others.""" flags = set(flags) status_flags, xstatus_flags = '', '' for flag in ('R', 'O'): if flag in flags: status_flags += flag flags.remove(flag) for flag in ('D', 'F', 'A'): if flag in flags: xstatus_flags += flag flags.remove(flag) xstatus_flags += ''.join(sorted(flags)) try: self.replace_header('Status', status_flags) except KeyError: self.add_header('Status', status_flags) try: self.replace_header('X-Status', xstatus_flags) except KeyError: self.add_header('X-Status', xstatus_flags) def add_flag(self, flag): """Set the given flag(s) without changing others.""" self.set_flags(''.join(set(self.get_flags()) \| set(flag))) def remove_flag(self, flag): """Unset the given string flag(s) without changing others.""" if 'Status' in self or 'X-Status' in self: self.set_flags(''.join(set(self.get_flags()) - set(flag))) def _explain_to(self, message): """Copy mbox- or MMDF-specific state to message insofar as possible.""" if isinstance(message, MaildirMessage): flags = set(self.get_flags()) if 'O' in flags: message.set_subdir('cur') if 'F' in flags: message.add_flag('F') if 'A' in flags: message.add_flag('R') if 'R' in flags: message.add_flag('S') if 'D' in flags: message.add_flag('T') del message['status'] del message['x-status'] maybe_date = ' '.join(self.get_from().split()[-5:]) try: message.set_date(calendar.timegm(time.strptime(maybe_date, '%a %b %d %H:%M:%S %Y'))) except (ValueError, OverflowError): pass elif isinstance(message, _mboxMMDFMessage): message.set_flags(self.get_flags()) message.set_from(self.get_from()) elif isinstance(message, MHMessage): flags = set(self.get_flags()) if 'R' not in flags: message.add_sequence('unseen') if 'A' in flags: message.add_sequence('replied') if 'F' in flags: message.add_sequence('flagged') del message['status'] del message['x-status'] elif isinstance(message, BabylMessage): flags = set(self.get_flags()) if 'R' not in flags: message.add_label('unseen') if 'D' in flags: message.add_label('deleted') if 'A' in flags: message.add_label('answered') del message['status'] del message['x-status'] elif isinstance(message, Message): pass else: raise TypeError('Cannot convert to specified type: %s' % type(message)) class mboxMessage(_mboxMMDFMessage): """Message with mbox-specific properties.""" class MHMessage(Message): """Message with MH-specific properties.""" _type_specific_attributes = ['_sequences'] def __init__(self, message=None): """Initialize an MHMessage instance.""" self._sequences = [] Message.__init__(self, message) def get_sequences(self): """Return a list of sequences that include the message.""" return self._sequences[:] def set_sequences(self, sequences): """Set the list of sequences that include the message.""" self._sequences = list(sequences) def add_sequence(self, sequence): """Add sequence to list of sequences including the message.""" if isinstance(sequence, str): if not sequence in self._sequences: self._sequences.append(sequence) else: raise TypeError('sequence type must be str: %s' % type(sequence)) def remove_sequence(self, sequence): """Remove sequence from the list of sequences including the message.""" try: self._sequences.remove(sequence) except ValueError: pass def _explain_to(self, message): """Copy MH-specific state to message insofar as possible.""" if isinstance(message, MaildirMessage): sequences = set(self.get_sequences()) if 'unseen' in sequences: message.set_subdir('cur') else: message.set_subdir('cur') message.add_flag('S') if 'flagged' in sequences: message.add_flag('F') if 'replied' in sequences: message.add_flag('R') elif isinstance(message, _mboxMMDFMessage): sequences = set(self.get_sequences()) if 'unseen' not in sequences: message.add_flag('RO') else: message.add_flag('O') if 'flagged' in sequences: message.add_flag('F') if 'replied' in sequences: message.add_flag('A') elif isinstance(message, MHMessage): for sequence in self.get_sequences(): message.add_sequence(sequence) elif isinstance(message, BabylMessage): sequences = set(self.get_sequences()) if 'unseen' in sequences: message.add_label('unseen') if 'replied' in sequences: message.add_label('answered') elif isinstance(message, Message): pass else: raise TypeError('Cannot convert to specified type: %s' % type(message)) class BabylMessage(Message): """Message with Babyl-specific properties.""" _type_specific_attributes = ['_labels', '_visible'] def __init__(self, message=None): """Initialize a BabylMessage instance.""" self._labels = [] self._visible = Message() Message.__init__(self, message) def get_labels(self): """Return a list of labels on the message.""" return self._labels[:] def set_labels(self, labels): """Set the list of labels on the message.""" self._labels = list(labels) def add_label(self, label): """Add label to list of labels on the message.""" if isinstance(label, str): if label not in self._labels: self._labels.append(label) else: raise TypeError('label must be a string: %s' % type(label)) def remove_label(self, label): """Remove label from the list of labels on the message.""" try: self._labels.remove(label) except ValueError: pass def get_visible(self): """Return a Message representation of visible headers.""" return Message(self._visible) def set_visible(self, visible): """Set the Message representation of visible headers.""" self._visible = Message(visible) def update_visible(self): """Update and/or sensibly generate a set of visible headers.""" for header in self._visible.keys(): if header in self: self._visible.replace_header(header, self[header]) else: del self._visible[header] for header in ('Date', 'From', 'Reply-To', 'To', 'CC', 'Subject'): if header in self and header not in self._visible: self._visible[header] = self[header] def _explain_to(self, message): """Copy Babyl-specific state to message insofar as possible.""" if isinstance(message, MaildirMessage): labels = set(self.get_labels()) if 'unseen' in labels: message.set_subdir('cur') else: message.set_subdir('cur') message.add_flag('S') if 'forwarded' in labels or 'resent' in labels: message.add_flag('P') if 'answered' in labels: message.add_flag('R') if 'deleted' in labels: message.add_flag('T') elif isinstance(message, _mboxMMDFMessage): labels = set(self.get_labels()) if 'unseen' not in labels: message.add_flag('RO') else: message.add_flag('O') if 'deleted' in labels: message.add_flag('D') if 'answered' in labels: message.add_flag('A') elif isinstance(message, MHMessage): labels = set(self.get_labels()) if 'unseen' in labels: message.add_sequence('unseen') if 'answered' in labels: message.add_sequence('replied') elif isinstance(message, BabylMessage): message.set_visible(self.get_visible()) for label in self.get_labels(): message.add_label(label) elif isinstance(message, Message): pass else: raise TypeError('Cannot convert to specified type: %s' % type(message)) class MMDFMessage(_mboxMMDFMessage): """Message with MMDF-specific properties.""" class _ProxyFile: """A read-only wrapper of a file.""" def __init__(self, f, pos=None): """Initialize a _ProxyFile.""" self._file = f if pos is None: self._pos = f.tell() else: self._pos = pos def read(self, size=None): """Read bytes.""" return self._read(size, self._file.read) def read1(self, size=None): """Read bytes.""" return self._read(size, self._file.read1) def readline(self, size=None): """Read a line.""" return self._read(size, self._file.readline) def readlines(self, sizehint=None): """Read multiple lines.""" result = [] for line in self: result.append(line) if sizehint is not None: sizehint -= len(line) if sizehint <= 0: break return result def __iter__(self): """Iterate over lines.""" while True: line = self.readline() if not line: return yield line def tell(self): """Return the position.""" return self._pos def seek(self, offset, whence=0): """Change position.""" if whence == 1: self._file.seek(self._pos) self._file.seek(offset, whence) self._pos = self._file.tell() def close(self): """Close the file.""" if hasattr(self, '_file'): try: if hasattr(self._file, 'close'): self._file.close() finally: del self._file def _read(self, size, read_method): """Read size bytes using read_method.""" if size is None: size = -1 self._file.seek(self._pos) result = read_method(size) self._pos = self._file.tell() return result def __enter__(self): """Context management protocol support.""" return self def __exit__(self, exc): self.close() def readable(self): return self._file.readable() def writable(self): return self._file.writable() def seekable(self): return self._file.seekable() def flush(self): return self._file.flush() @property def closed(self): if not hasattr(self, '_file'): return True if not hasattr(self._file, 'closed'): return False return self._file.closed class _PartialFile(_ProxyFile): """A read-only wrapper of part of a file.""" def __init__(self, f, start=None, stop=None): """Initialize a _PartialFile.""" _ProxyFile.__init__(self, f, start) self._start = start self._stop = stop def tell(self): """Return the position with respect to start.""" return _ProxyFile.tell(self) - self._start def seek(self, offset, whence=0): """Change position, possibly with respect to start or stop.""" if whence == 0: self._pos = self._start whence = 1 elif whence == 2: self._pos = self._stop whence = 1 _ProxyFile.seek(self, offset, whence) def _read(self, size, read_method): """Read size bytes using read_method, honoring start and stop.""" remaining = self._stop - self._pos if remaining <= 0: return b'' if size is None or size < 0 or size > remaining: size = remaining return _ProxyFile._read(self, size, read_method) def close(self): # do not close the underlying file object for partial files, # since it's global to the mailbox object if hasattr(self, '_file'): del self._file def _lock_file(f, dotlock=True): """Lock file f using lockf and dot locking.""" dotlock_done = False try: if fcntl: try: fcntl.lockf(f, fcntl.LOCK_EX \| fcntl.LOCK_NB) except OSError as e: if e.errno in (errno.EAGAIN, errno.EACCES, errno.EROFS): raise ExternalClashError('lockf: lock unavailable: %s' % f.name) else: raise if dotlock: try: pre_lock = _create_temporary(f.name + '.lock') pre_lock.close() except OSError as e: if e.errno in (errno.EACCES, errno.EROFS): return # Without write access, just skip dotlocking. else: raise try: try: os.link(pre_lock.name, f.name + '.lock') dotlock_done = True except (AttributeError, PermissionError): os.rename(pre_lock.name, f.name + '.lock') dotlock_done = True else: os.unlink(pre_lock.name) except FileExistsError: os.remove(pre_lock.name) raise ExternalClashError('dot lock unavailable: %s' % f.name) except: if fcntl: fcntl.lockf(f, fcntl.LOCK_UN) if dotlock_done: os.remove(f.name + '.lock') raise def _unlock_file(f): """Unlock file f using lockf and dot locking.""" if fcntl: fcntl.lockf(f, fcntl.LOCK_UN) if os.path.exists(f.name + '.lock'): os.remove(f.name + '.lock') def _create_carefully(path): """Create a file if it doesn't exist and open for reading and writing.""" fd = os.open(path, os.O_CREAT \| os.O_EXCL \| os.O_RDWR, 0o666) try: return open(path, 'rb+') finally: os.close(fd) def _create_temporary(path): """Create a temp file based on path and open for reading and writing.""" return _create_carefully('%s.%s.%s.%s' % (path, int(time.time()), socket.gethostname(), os.getpid())) def _sync_flush(f): """Ensure changes to file f are physically on disk.""" f.flush() if hasattr(os, 'fsync'): os.fsync(f.fileno()) def _sync_close(f): """Close file f, ensuring all changes are physically on disk.""" _sync_flush(f) f.close() class Error(Exception): """Raised for module-specific errors.""" class NoSuchMailboxError(Error): """The specified mailbox does not exist and won't be created.""" class NotEmptyError(Error): """The specified mailbox is not empty and deletion was requested.""" class ExternalClashError(Error): """Another process caused an action to fail.""" class FormatError(Error): """A file appears to have an invalid format.""" Back

Edit File : mailbox.py | Size : 76.78 KB

"""Read/write support for Maildir, mbox, MH, Babyl, and MMDF mailboxes."""

# Notes for authors of new mailbox subclasses:
#
# Remember to fsync() changes to disk before closing a modified file
# or returning from a flush() method.  See functions _sync_flush() and
# _sync_close().

import os
import time
import calendar
import socket
import errno
import copy
import warnings
import email
import email.message
import email.generator
import io
import contextlib
try:
    import fcntl
except ImportError:
    fcntl = None

__all__ = ['Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF',
           'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage',
           'BabylMessage', 'MMDFMessage', 'Error', 'NoSuchMailboxError',
           'NotEmptyError', 'ExternalClashError', 'FormatError']

linesep = os.linesep.encode('ascii')

class Mailbox:
    """A group of messages in a particular place."""

def __init__(self, path, factory=None, create=True):
        """Initialize a Mailbox instance."""
        self._path = os.path.abspath(os.path.expanduser(path))
        self._factory = factory

def add(self, message):
        """Add message and return assigned key."""
        raise NotImplementedError('Method must be implemented by subclass')

def remove(self, key):
        """Remove the keyed message; raise KeyError if it doesn't exist."""
        raise NotImplementedError('Method must be implemented by subclass')

def __delitem__(self, key):
        self.remove(key)

def discard(self, key):
        """If the keyed message exists, remove it."""
        try:
            self.remove(key)
        except KeyError:
            pass

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        raise NotImplementedError('Method must be implemented by subclass')

def get(self, key, default=None):
        """Return the keyed message, or default if it doesn't exist."""
        try:
            return self.__getitem__(key)
        except KeyError:
            return default

def __getitem__(self, key):
        """Return the keyed message; raise KeyError if it doesn't exist."""
        if not self._factory:
            return self.get_message(key)
        else:
            with contextlib.closing(self.get_file(key)) as file:
                return self._factory(file)

def get_message(self, key):
        """Return a Message representation or raise a KeyError."""
        raise NotImplementedError('Method must be implemented by subclass')

def get_string(self, key):
        """Return a string representation or raise a KeyError.

Uses email.message.Message to create a 7bit clean string
        representation of the message."""
        return email.message_from_bytes(self.get_bytes(key)).as_string()

def get_bytes(self, key):
        """Return a byte string representation or raise a KeyError."""
        raise NotImplementedError('Method must be implemented by subclass')

def get_file(self, key):
        """Return a file-like representation or raise a KeyError."""
        raise NotImplementedError('Method must be implemented by subclass')

def iterkeys(self):
        """Return an iterator over keys."""
        raise NotImplementedError('Method must be implemented by subclass')

def keys(self):
        """Return a list of keys."""
        return list(self.iterkeys())

def itervalues(self):
        """Return an iterator over all messages."""
        for key in self.iterkeys():
            try:
                value = self[key]
            except KeyError:
                continue
            yield value

def __iter__(self):
        return self.itervalues()

def values(self):
        """Return a list of messages. Memory intensive."""
        return list(self.itervalues())

def iteritems(self):
        """Return an iterator over (key, message) tuples."""
        for key in self.iterkeys():
            try:
                value = self[key]
            except KeyError:
                continue
            yield (key, value)

def items(self):
        """Return a list of (key, message) tuples. Memory intensive."""
        return list(self.iteritems())

def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        raise NotImplementedError('Method must be implemented by subclass')

def __len__(self):
        """Return a count of messages in the mailbox."""
        raise NotImplementedError('Method must be implemented by subclass')

def clear(self):
        """Delete all messages."""
        for key in self.keys():
            self.discard(key)

def pop(self, key, default=None):
        """Delete the keyed message and return it, or default."""
        try:
            result = self[key]
        except KeyError:
            return default
        self.discard(key)
        return result

def popitem(self):
        """Delete an arbitrary (key, message) pair and return it."""
        for key in self.iterkeys():
            return (key, self.pop(key))     # This is only run once.
        else:
            raise KeyError('No messages in mailbox')

def update(self, arg=None):
        """Change the messages that correspond to certain keys."""
        if hasattr(arg, 'iteritems'):
            source = arg.iteritems()
        elif hasattr(arg, 'items'):
            source = arg.items()
        else:
            source = arg
        bad_key = False
        for key, message in source:
            try:
                self[key] = message
            except KeyError:
                bad_key = True
        if bad_key:
            raise KeyError('No message with key(s)')

def flush(self):
        """Write any pending changes to the disk."""
        raise NotImplementedError('Method must be implemented by subclass')

def lock(self):
        """Lock the mailbox."""
        raise NotImplementedError('Method must be implemented by subclass')

def unlock(self):
        """Unlock the mailbox if it is locked."""
        raise NotImplementedError('Method must be implemented by subclass')

def close(self):
        """Flush and close the mailbox."""
        raise NotImplementedError('Method must be implemented by subclass')

def _string_to_bytes(self, message):
        # If a message is not 7bit clean, we refuse to handle it since it
        # likely came from reading invalid messages in text mode, and that way
        # lies mojibake.
        try:
            return message.encode('ascii')
        except UnicodeError:
            raise ValueError("String input must be ASCII-only; "
                "use bytes or a Message instead")

# Whether each message must end in a newline
    _append_newline = False

def _dump_message(self, message, target, mangle_from_=False):
        # This assumes the target file is open in binary mode.
        """Dump message contents to target file."""
        if isinstance(message, email.message.Message):
            buffer = io.BytesIO()
            gen = email.generator.BytesGenerator(buffer, mangle_from_, 0)
            gen.flatten(message)
            buffer.seek(0)
            data = buffer.read()
            data = data.replace(b'\n', linesep)
            target.write(data)
            if self._append_newline and not data.endswith(linesep):
                # Make sure the message ends with a newline
                target.write(linesep)
        elif isinstance(message, (str, bytes, io.StringIO)):
            if isinstance(message, io.StringIO):
                warnings.warn("Use of StringIO input is deprecated, "
                    "use BytesIO instead", DeprecationWarning, 3)
                message = message.getvalue()
            if isinstance(message, str):
                message = self._string_to_bytes(message)
            if mangle_from_:
                message = message.replace(b'\nFrom ', b'\n>From ')
            message = message.replace(b'\n', linesep)
            target.write(message)
            if self._append_newline and not message.endswith(linesep):
                # Make sure the message ends with a newline
                target.write(linesep)
        elif hasattr(message, 'read'):
            if hasattr(message, 'buffer'):
                warnings.warn("Use of text mode files is deprecated, "
                    "use a binary mode file instead", DeprecationWarning, 3)
                message = message.buffer
            lastline = None
            while True:
                line = message.readline()
                # Universal newline support.
                if line.endswith(b'\r\n'):
                    line = line[:-2] + b'\n'
                elif line.endswith(b'\r'):
                    line = line[:-1] + b'\n'
                if not line:
                    break
                if mangle_from_ and line.startswith(b'From '):
                    line = b'>From ' + line[5:]
                line = line.replace(b'\n', linesep)
                target.write(line)
                lastline = line
            if self._append_newline and lastline and not lastline.endswith(linesep):
                # Make sure the message ends with a newline
                target.write(linesep)
        else:
            raise TypeError('Invalid message type: %s' % type(message))

class Maildir(Mailbox):
    """A qmail-style Maildir mailbox."""

colon = ':'

def __init__(self, dirname, factory=None, create=True):
        """Initialize a Maildir instance."""
        Mailbox.__init__(self, dirname, factory, create)
        self._paths = {
            'tmp': os.path.join(self._path, 'tmp'),
            'new': os.path.join(self._path, 'new'),
            'cur': os.path.join(self._path, 'cur'),
            }
        if not os.path.exists(self._path):
            if create:
                os.mkdir(self._path, 0o700)
                for path in self._paths.values():
                    os.mkdir(path, 0o700)
            else:
                raise NoSuchMailboxError(self._path)
        self._toc = {}
        self._toc_mtimes = {'cur': 0, 'new': 0}
        self._last_read = 0         # Records last time we read cur/new
        self._skewfactor = 0.1      # Adjust if os/fs clocks are skewing

def add(self, message):
        """Add message and return assigned key."""
        tmp_file = self._create_tmp()
        try:
            self._dump_message(message, tmp_file)
        except BaseException:
            tmp_file.close()
            os.remove(tmp_file.name)
            raise
        _sync_close(tmp_file)
        if isinstance(message, MaildirMessage):
            subdir = message.get_subdir()
            suffix = self.colon + message.get_info()
            if suffix == self.colon:
                suffix = ''
        else:
            subdir = 'new'
            suffix = ''
        uniq = os.path.basename(tmp_file.name).split(self.colon)[0]
        dest = os.path.join(self._path, subdir, uniq + suffix)
        if isinstance(message, MaildirMessage):
            os.utime(tmp_file.name,
                     (os.path.getatime(tmp_file.name), message.get_date()))
        # No file modification should be done after the file is moved to its
        # final position in order to prevent race conditions with changes
        # from other programs
        try:
            try:
                os.link(tmp_file.name, dest)
            except (AttributeError, PermissionError):
                os.rename(tmp_file.name, dest)
            else:
                os.remove(tmp_file.name)
        except OSError as e:
            os.remove(tmp_file.name)
            if e.errno == errno.EEXIST:
                raise ExternalClashError('Name clash with existing message: %s'
                                         % dest)
            else:
                raise
        return uniq

def remove(self, key):
        """Remove the keyed message; raise KeyError if it doesn't exist."""
        os.remove(os.path.join(self._path, self._lookup(key)))

def discard(self, key):
        """If the keyed message exists, remove it."""
        # This overrides an inapplicable implementation in the superclass.
        try:
            self.remove(key)
        except (KeyError, FileNotFoundError):
            pass

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        old_subpath = self._lookup(key)
        temp_key = self.add(message)
        temp_subpath = self._lookup(temp_key)
        if isinstance(message, MaildirMessage):
            # temp's subdir and suffix were specified by message.
            dominant_subpath = temp_subpath
        else:
            # temp's subdir and suffix were defaults from add().
            dominant_subpath = old_subpath
        subdir = os.path.dirname(dominant_subpath)
        if self.colon in dominant_subpath:
            suffix = self.colon + dominant_subpath.split(self.colon)[-1]
        else:
            suffix = ''
        self.discard(key)
        tmp_path = os.path.join(self._path, temp_subpath)
        new_path = os.path.join(self._path, subdir, key + suffix)
        if isinstance(message, MaildirMessage):
            os.utime(tmp_path,
                     (os.path.getatime(tmp_path), message.get_date()))
        # No file modification should be done after the file is moved to its
        # final position in order to prevent race conditions with changes
        # from other programs
        os.rename(tmp_path, new_path)

def get_message(self, key):
        """Return a Message representation or raise a KeyError."""
        subpath = self._lookup(key)
        with open(os.path.join(self._path, subpath), 'rb') as f:
            if self._factory:
                msg = self._factory(f)
            else:
                msg = MaildirMessage(f)
        subdir, name = os.path.split(subpath)
        msg.set_subdir(subdir)
        if self.colon in name:
            msg.set_info(name.split(self.colon)[-1])
        msg.set_date(os.path.getmtime(os.path.join(self._path, subpath)))
        return msg

def get_bytes(self, key):
        """Return a bytes representation or raise a KeyError."""
        with open(os.path.join(self._path, self._lookup(key)), 'rb') as f:
            return f.read().replace(linesep, b'\n')

def get_file(self, key):
        """Return a file-like representation or raise a KeyError."""
        f = open(os.path.join(self._path, self._lookup(key)), 'rb')
        return _ProxyFile(f)

def iterkeys(self):
        """Return an iterator over keys."""
        self._refresh()
        for key in self._toc:
            try:
                self._lookup(key)
            except KeyError:
                continue
            yield key

def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        self._refresh()
        return key in self._toc

def __len__(self):
        """Return a count of messages in the mailbox."""
        self._refresh()
        return len(self._toc)

def flush(self):
        """Write any pending changes to disk."""
        # Maildir changes are always written immediately, so there's nothing
        # to do.
        pass

def lock(self):
        """Lock the mailbox."""
        return

def unlock(self):
        """Unlock the mailbox if it is locked."""
        return

def close(self):
        """Flush and close the mailbox."""
        return

def list_folders(self):
        """Return a list of folder names."""
        result = []
        for entry in os.listdir(self._path):
            if len(entry) > 1 and entry[0] == '.' and \
               os.path.isdir(os.path.join(self._path, entry)):
                result.append(entry[1:])
        return result

def get_folder(self, folder):
        """Return a Maildir instance for the named folder."""
        return Maildir(os.path.join(self._path, '.' + folder),
                       factory=self._factory,
                       create=False)

def add_folder(self, folder):
        """Create a folder and return a Maildir instance representing it."""
        path = os.path.join(self._path, '.' + folder)
        result = Maildir(path, factory=self._factory)
        maildirfolder_path = os.path.join(path, 'maildirfolder')
        if not os.path.exists(maildirfolder_path):
            os.close(os.open(maildirfolder_path, os.O_CREAT | os.O_WRONLY,
                0o666))
        return result

def remove_folder(self, folder):
        """Delete the named folder, which must be empty."""
        path = os.path.join(self._path, '.' + folder)
        for entry in os.listdir(os.path.join(path, 'new')) + \
                     os.listdir(os.path.join(path, 'cur')):
            if len(entry) < 1 or entry[0] != '.':
                raise NotEmptyError('Folder contains message(s): %s' % folder)
        for entry in os.listdir(path):
            if entry != 'new' and entry != 'cur' and entry != 'tmp' and \
               os.path.isdir(os.path.join(path, entry)):
                raise NotEmptyError("Folder contains subdirectory '%s': %s" %
                                    (folder, entry))
        for root, dirs, files in os.walk(path, topdown=False):
            for entry in files:
                os.remove(os.path.join(root, entry))
            for entry in dirs:
                os.rmdir(os.path.join(root, entry))
        os.rmdir(path)

def clean(self):
        """Delete old files in "tmp"."""
        now = time.time()
        for entry in os.listdir(os.path.join(self._path, 'tmp')):
            path = os.path.join(self._path, 'tmp', entry)
            if now - os.path.getatime(path) > 129600:   # 60 * 60 * 36
                os.remove(path)

_count = 1  # This is used to generate unique file names.

def _create_tmp(self):
        """Create a file in the tmp subdirectory and open and return it."""
        now = time.time()
        hostname = socket.gethostname()
        if '/' in hostname:
            hostname = hostname.replace('/', r'\057')
        if ':' in hostname:
            hostname = hostname.replace(':', r'\072')
        uniq = "%s.M%sP%sQ%s.%s" % (int(now), int(now % 1 * 1e6), os.getpid(),
                                    Maildir._count, hostname)
        path = os.path.join(self._path, 'tmp', uniq)
        try:
            os.stat(path)
        except FileNotFoundError:
            Maildir._count += 1
            try:
                return _create_carefully(path)
            except FileExistsError:
                pass

# Fall through to here if stat succeeded or open raised EEXIST.
        raise ExternalClashError('Name clash prevented file creation: %s' %
                                 path)

def _refresh(self):
        """Update table of contents mapping."""
        # If it has been less than two seconds since the last _refresh() call,
        # we have to unconditionally re-read the mailbox just in case it has
        # been modified, because os.path.mtime() has a 2 sec resolution in the
        # most common worst case (FAT) and a 1 sec resolution typically.  This
        # results in a few unnecessary re-reads when _refresh() is called
        # multiple times in that interval, but once the clock ticks over, we
        # will only re-read as needed.  Because the filesystem might be being
        # served by an independent system with its own clock, we record and
        # compare with the mtimes from the filesystem.  Because the other
        # system's clock might be skewing relative to our clock, we add an
        # extra delta to our wait.  The default is one tenth second, but is an
        # instance variable and so can be adjusted if dealing with a
        # particularly skewed or irregular system.
        if time.time() - self._last_read > 2 + self._skewfactor:
            refresh = False
            for subdir in self._toc_mtimes:
                mtime = os.path.getmtime(self._paths[subdir])
                if mtime > self._toc_mtimes[subdir]:
                    refresh = True
                self._toc_mtimes[subdir] = mtime
            if not refresh:
                return
        # Refresh toc
        self._toc = {}
        for subdir in self._toc_mtimes:
            path = self._paths[subdir]
            for entry in os.listdir(path):
                p = os.path.join(path, entry)
                if os.path.isdir(p):
                    continue
                uniq = entry.split(self.colon)[0]
                self._toc[uniq] = os.path.join(subdir, entry)
        self._last_read = time.time()

def _lookup(self, key):
        """Use TOC to return subpath for given key, or raise a KeyError."""
        try:
            if os.path.exists(os.path.join(self._path, self._toc[key])):
                return self._toc[key]
        except KeyError:
            pass
        self._refresh()
        try:
            return self._toc[key]
        except KeyError:
            raise KeyError('No message with key: %s' % key)

# This method is for backward compatibility only.
    def next(self):
        """Return the next message in a one-time iteration."""
        if not hasattr(self, '_onetime_keys'):
            self._onetime_keys = self.iterkeys()
        while True:
            try:
                return self[next(self._onetime_keys)]
            except StopIteration:
                return None
            except KeyError:
                continue

class _singlefileMailbox(Mailbox):
    """A single-file mailbox."""

def __init__(self, path, factory=None, create=True):
        """Initialize a single-file mailbox."""
        Mailbox.__init__(self, path, factory, create)
        try:
            f = open(self._path, 'rb+')
        except OSError as e:
            if e.errno == errno.ENOENT:
                if create:
                    f = open(self._path, 'wb+')
                else:
                    raise NoSuchMailboxError(self._path)
            elif e.errno in (errno.EACCES, errno.EROFS):
                f = open(self._path, 'rb')
            else:
                raise
        self._file = f
        self._toc = None
        self._next_key = 0
        self._pending = False       # No changes require rewriting the file.
        self._pending_sync = False  # No need to sync the file
        self._locked = False
        self._file_length = None    # Used to record mailbox size

def add(self, message):
        """Add message and return assigned key."""
        self._lookup()
        self._toc[self._next_key] = self._append_message(message)
        self._next_key += 1
        # _append_message appends the message to the mailbox file. We
        # don't need a full rewrite + rename, sync is enough.
        self._pending_sync = True
        return self._next_key - 1

def remove(self, key):
        """Remove the keyed message; raise KeyError if it doesn't exist."""
        self._lookup(key)
        del self._toc[key]
        self._pending = True

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        self._lookup(key)
        self._toc[key] = self._append_message(message)
        self._pending = True

def iterkeys(self):
        """Return an iterator over keys."""
        self._lookup()
        yield from self._toc.keys()

def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        self._lookup()
        return key in self._toc

def __len__(self):
        """Return a count of messages in the mailbox."""
        self._lookup()
        return len(self._toc)

def lock(self):
        """Lock the mailbox."""
        if not self._locked:
            _lock_file(self._file)
            self._locked = True

def unlock(self):
        """Unlock the mailbox if it is locked."""
        if self._locked:
            _unlock_file(self._file)
            self._locked = False

def flush(self):
        """Write any pending changes to disk."""
        if not self._pending:
            if self._pending_sync:
                # Messages have only been added, so syncing the file
                # is enough.
                _sync_flush(self._file)
                self._pending_sync = False
            return

# In order to be writing anything out at all, self._toc must
        # already have been generated (and presumably has been modified
        # by adding or deleting an item).
        assert self._toc is not None

# Check length of self._file; if it's changed, some other process
        # has modified the mailbox since we scanned it.
        self._file.seek(0, 2)
        cur_len = self._file.tell()
        if cur_len != self._file_length:
            raise ExternalClashError('Size of mailbox file changed '
                                     '(expected %i, found %i)' %
                                     (self._file_length, cur_len))

new_file = _create_temporary(self._path)
        try:
            new_toc = {}
            self._pre_mailbox_hook(new_file)
            for key in sorted(self._toc.keys()):
                start, stop = self._toc[key]
                self._file.seek(start)
                self._pre_message_hook(new_file)
                new_start = new_file.tell()
                while True:
                    buffer = self._file.read(min(4096,
                                                 stop - self._file.tell()))
                    if not buffer:
                        break
                    new_file.write(buffer)
                new_toc[key] = (new_start, new_file.tell())
                self._post_message_hook(new_file)
            self._file_length = new_file.tell()
        except:
            new_file.close()
            os.remove(new_file.name)
            raise
        _sync_close(new_file)
        # self._file is about to get replaced, so no need to sync.
        self._file.close()
        # Make sure the new file's mode is the same as the old file's
        mode = os.stat(self._path).st_mode
        os.chmod(new_file.name, mode)
        try:
            os.rename(new_file.name, self._path)
        except FileExistsError:
            os.remove(self._path)
            os.rename(new_file.name, self._path)
        self._file = open(self._path, 'rb+')
        self._toc = new_toc
        self._pending = False
        self._pending_sync = False
        if self._locked:
            _lock_file(self._file, dotlock=False)

def _pre_mailbox_hook(self, f):
        """Called before writing the mailbox to file f."""
        return

def _pre_message_hook(self, f):
        """Called before writing each message to file f."""
        return

def _post_message_hook(self, f):
        """Called after writing each message to file f."""
        return

def close(self):
        """Flush and close the mailbox."""
        try:
            self.flush()
        finally:
            try:
                if self._locked:
                    self.unlock()
            finally:
                self._file.close()  # Sync has been done by self.flush() above.

def _lookup(self, key=None):
        """Return (start, stop) or raise KeyError."""
        if self._toc is None:
            self._generate_toc()
        if key is not None:
            try:
                return self._toc[key]
            except KeyError:
                raise KeyError('No message with key: %s' % key)

def _append_message(self, message):
        """Append message to mailbox and return (start, stop) offsets."""
        self._file.seek(0, 2)
        before = self._file.tell()
        if len(self._toc) == 0 and not self._pending:
            # This is the first message, and the _pre_mailbox_hook
            # hasn't yet been called. If self._pending is True,
            # messages have been removed, so _pre_mailbox_hook must
            # have been called already.
            self._pre_mailbox_hook(self._file)
        try:
            self._pre_message_hook(self._file)
            offsets = self._install_message(message)
            self._post_message_hook(self._file)
        except BaseException:
            self._file.truncate(before)
            raise
        self._file.flush()
        self._file_length = self._file.tell()  # Record current length of mailbox
        return offsets

class _mboxMMDF(_singlefileMailbox):
    """An mbox or MMDF mailbox."""

_mangle_from_ = True

def get_message(self, key):
        """Return a Message representation or raise a KeyError."""
        start, stop = self._lookup(key)
        self._file.seek(start)
        from_line = self._file.readline().replace(linesep, b'')
        string = self._file.read(stop - self._file.tell())
        msg = self._message_factory(string.replace(linesep, b'\n'))
        msg.set_from(from_line[5:].decode('ascii'))
        return msg

def get_string(self, key, from_=False):
        """Return a string representation or raise a KeyError."""
        return email.message_from_bytes(
            self.get_bytes(key)).as_string(unixfrom=from_)

def get_bytes(self, key, from_=False):
        """Return a string representation or raise a KeyError."""
        start, stop = self._lookup(key)
        self._file.seek(start)
        if not from_:
            self._file.readline()
        string = self._file.read(stop - self._file.tell())
        return string.replace(linesep, b'\n')

def get_file(self, key, from_=False):
        """Return a file-like representation or raise a KeyError."""
        start, stop = self._lookup(key)
        self._file.seek(start)
        if not from_:
            self._file.readline()
        return _PartialFile(self._file, self._file.tell(), stop)

def _install_message(self, message):
        """Format a message and blindly write to self._file."""
        from_line = None
        if isinstance(message, str):
            message = self._string_to_bytes(message)
        if isinstance(message, bytes) and message.startswith(b'From '):
            newline = message.find(b'\n')
            if newline != -1:
                from_line = message[:newline]
                message = message[newline + 1:]
            else:
                from_line = message
                message = b''
        elif isinstance(message, _mboxMMDFMessage):
            author = message.get_from().encode('ascii')
            from_line = b'From ' + author
        elif isinstance(message, email.message.Message):
            from_line = message.get_unixfrom()  # May be None.
            if from_line is not None:
                from_line = from_line.encode('ascii')
        if from_line is None:
            from_line = b'From MAILER-DAEMON ' + time.asctime(time.gmtime()).encode()
        start = self._file.tell()
        self._file.write(from_line + linesep)
        self._dump_message(message, self._file, self._mangle_from_)
        stop = self._file.tell()
        return (start, stop)

class mbox(_mboxMMDF):
    """A classic mbox mailbox."""

_mangle_from_ = True

# All messages must end in a newline character, and
    # _post_message_hooks outputs an empty line between messages.
    _append_newline = True

def __init__(self, path, factory=None, create=True):
        """Initialize an mbox mailbox."""
        self._message_factory = mboxMessage
        _mboxMMDF.__init__(self, path, factory, create)

def _post_message_hook(self, f):
        """Called after writing each message to file f."""
        f.write(linesep)

def _generate_toc(self):
        """Generate key-to-(start, stop) table of contents."""
        starts, stops = [], []
        last_was_empty = False
        self._file.seek(0)
        while True:
            line_pos = self._file.tell()
            line = self._file.readline()
            if line.startswith(b'From '):
                if len(stops) < len(starts):
                    if last_was_empty:
                        stops.append(line_pos - len(linesep))
                    else:
                        # The last line before the "From " line wasn't
                        # blank, but we consider it a start of a
                        # message anyway.
                        stops.append(line_pos)
                starts.append(line_pos)
                last_was_empty = False
            elif not line:
                if last_was_empty:
                    stops.append(line_pos - len(linesep))
                else:
                    stops.append(line_pos)
                break
            elif line == linesep:
                last_was_empty = True
            else:
                last_was_empty = False
        self._toc = dict(enumerate(zip(starts, stops)))
        self._next_key = len(self._toc)
        self._file_length = self._file.tell()

class MMDF(_mboxMMDF):
    """An MMDF mailbox."""

def __init__(self, path, factory=None, create=True):
        """Initialize an MMDF mailbox."""
        self._message_factory = MMDFMessage
        _mboxMMDF.__init__(self, path, factory, create)

def _pre_message_hook(self, f):
        """Called before writing each message to file f."""
        f.write(b'\001\001\001\001' + linesep)

def _post_message_hook(self, f):
        """Called after writing each message to file f."""
        f.write(linesep + b'\001\001\001\001' + linesep)

def _generate_toc(self):
        """Generate key-to-(start, stop) table of contents."""
        starts, stops = [], []
        self._file.seek(0)
        next_pos = 0
        while True:
            line_pos = next_pos
            line = self._file.readline()
            next_pos = self._file.tell()
            if line.startswith(b'\001\001\001\001' + linesep):
                starts.append(next_pos)
                while True:
                    line_pos = next_pos
                    line = self._file.readline()
                    next_pos = self._file.tell()
                    if line == b'\001\001\001\001' + linesep:
                        stops.append(line_pos - len(linesep))
                        break
                    elif not line:
                        stops.append(line_pos)
                        break
            elif not line:
                break
        self._toc = dict(enumerate(zip(starts, stops)))
        self._next_key = len(self._toc)
        self._file.seek(0, 2)
        self._file_length = self._file.tell()

class MH(Mailbox):
    """An MH mailbox."""

def __init__(self, path, factory=None, create=True):
        """Initialize an MH instance."""
        Mailbox.__init__(self, path, factory, create)
        if not os.path.exists(self._path):
            if create:
                os.mkdir(self._path, 0o700)
                os.close(os.open(os.path.join(self._path, '.mh_sequences'),
                                 os.O_CREAT | os.O_EXCL | os.O_WRONLY, 0o600))
            else:
                raise NoSuchMailboxError(self._path)
        self._locked = False

def add(self, message):
        """Add message and return assigned key."""
        keys = self.keys()
        if len(keys) == 0:
            new_key = 1
        else:
            new_key = max(keys) + 1
        new_path = os.path.join(self._path, str(new_key))
        f = _create_carefully(new_path)
        closed = False
        try:
            if self._locked:
                _lock_file(f)
            try:
                try:
                    self._dump_message(message, f)
                except BaseException:
                    # Unlock and close so it can be deleted on Windows
                    if self._locked:
                        _unlock_file(f)
                    _sync_close(f)
                    closed = True
                    os.remove(new_path)
                    raise
                if isinstance(message, MHMessage):
                    self._dump_sequences(message, new_key)
            finally:
                if self._locked:
                    _unlock_file(f)
        finally:
            if not closed:
                _sync_close(f)
        return new_key

def remove(self, key):
        """Remove the keyed message; raise KeyError if it doesn't exist."""
        path = os.path.join(self._path, str(key))
        try:
            f = open(path, 'rb+')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        else:
            f.close()
            os.remove(path)

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        path = os.path.join(self._path, str(key))
        try:
            f = open(path, 'rb+')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        try:
            if self._locked:
                _lock_file(f)
            try:
                os.close(os.open(path, os.O_WRONLY | os.O_TRUNC))
                self._dump_message(message, f)
                if isinstance(message, MHMessage):
                    self._dump_sequences(message, key)
            finally:
                if self._locked:
                    _unlock_file(f)
        finally:
            _sync_close(f)

def get_message(self, key):
        """Return a Message representation or raise a KeyError."""
        try:
            if self._locked:
                f = open(os.path.join(self._path, str(key)), 'rb+')
            else:
                f = open(os.path.join(self._path, str(key)), 'rb')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        with f:
            if self._locked:
                _lock_file(f)
            try:
                msg = MHMessage(f)
            finally:
                if self._locked:
                    _unlock_file(f)
        for name, key_list in self.get_sequences().items():
            if key in key_list:
                msg.add_sequence(name)
        return msg

def get_bytes(self, key):
        """Return a bytes representation or raise a KeyError."""
        try:
            if self._locked:
                f = open(os.path.join(self._path, str(key)), 'rb+')
            else:
                f = open(os.path.join(self._path, str(key)), 'rb')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        with f:
            if self._locked:
                _lock_file(f)
            try:
                return f.read().replace(linesep, b'\n')
            finally:
                if self._locked:
                    _unlock_file(f)

def get_file(self, key):
        """Return a file-like representation or raise a KeyError."""
        try:
            f = open(os.path.join(self._path, str(key)), 'rb')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        return _ProxyFile(f)

def iterkeys(self):
        """Return an iterator over keys."""
        return iter(sorted(int(entry) for entry in os.listdir(self._path)
                                      if entry.isdigit()))

def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        return os.path.exists(os.path.join(self._path, str(key)))

def __len__(self):
        """Return a count of messages in the mailbox."""
        return len(list(self.iterkeys()))

def lock(self):
        """Lock the mailbox."""
        if not self._locked:
            self._file = open(os.path.join(self._path, '.mh_sequences'), 'rb+')
            _lock_file(self._file)
            self._locked = True

def unlock(self):
        """Unlock the mailbox if it is locked."""
        if self._locked:
            _unlock_file(self._file)
            _sync_close(self._file)
            del self._file
            self._locked = False

def flush(self):
        """Write any pending changes to the disk."""
        return

def close(self):
        """Flush and close the mailbox."""
        if self._locked:
            self.unlock()

def list_folders(self):
        """Return a list of folder names."""
        result = []
        for entry in os.listdir(self._path):
            if os.path.isdir(os.path.join(self._path, entry)):
                result.append(entry)
        return result

def get_folder(self, folder):
        """Return an MH instance for the named folder."""
        return MH(os.path.join(self._path, folder),
                  factory=self._factory, create=False)

def add_folder(self, folder):
        """Create a folder and return an MH instance representing it."""
        return MH(os.path.join(self._path, folder),
                  factory=self._factory)

def remove_folder(self, folder):
        """Delete the named folder, which must be empty."""
        path = os.path.join(self._path, folder)
        entries = os.listdir(path)
        if entries == ['.mh_sequences']:
            os.remove(os.path.join(path, '.mh_sequences'))
        elif entries == []:
            pass
        else:
            raise NotEmptyError('Folder not empty: %s' % self._path)
        os.rmdir(path)

def get_sequences(self):
        """Return a name-to-key-list dictionary to define each sequence."""
        results = {}
        with open(os.path.join(self._path, '.mh_sequences'), 'r', encoding='ASCII') as f:
            all_keys = set(self.keys())
            for line in f:
                try:
                    name, contents = line.split(':')
                    keys = set()
                    for spec in contents.split():
                        if spec.isdigit():
                            keys.add(int(spec))
                        else:
                            start, stop = (int(x) for x in spec.split('-'))
                            keys.update(range(start, stop + 1))
                    results[name] = [key for key in sorted(keys) \
                                         if key in all_keys]
                    if len(results[name]) == 0:
                        del results[name]
                except ValueError:
                    raise FormatError('Invalid sequence specification: %s' %
                                      line.rstrip())
        return results

def set_sequences(self, sequences):
        """Set sequences using the given name-to-key-list dictionary."""
        f = open(os.path.join(self._path, '.mh_sequences'), 'r+', encoding='ASCII')
        try:
            os.close(os.open(f.name, os.O_WRONLY | os.O_TRUNC))
            for name, keys in sequences.items():
                if len(keys) == 0:
                    continue
                f.write(name + ':')
                prev = None
                completing = False
                for key in sorted(set(keys)):
                    if key - 1 == prev:
                        if not completing:
                            completing = True
                            f.write('-')
                    elif completing:
                        completing = False
                        f.write('%s %s' % (prev, key))
                    else:
                        f.write(' %s' % key)
                    prev = key
                if completing:
                    f.write(str(prev) + '\n')
                else:
                    f.write('\n')
        finally:
            _sync_close(f)

def pack(self):
        """Re-name messages to eliminate numbering gaps. Invalidates keys."""
        sequences = self.get_sequences()
        prev = 0
        changes = []
        for key in self.iterkeys():
            if key - 1 != prev:
                changes.append((key, prev + 1))
                try:
                    os.link(os.path.join(self._path, str(key)),
                            os.path.join(self._path, str(prev + 1)))
                except (AttributeError, PermissionError):
                    os.rename(os.path.join(self._path, str(key)),
                              os.path.join(self._path, str(prev + 1)))
                else:
                    os.unlink(os.path.join(self._path, str(key)))
            prev += 1
        self._next_key = prev + 1
        if len(changes) == 0:
            return
        for name, key_list in sequences.items():
            for old, new in changes:
                if old in key_list:
                    key_list[key_list.index(old)] = new
        self.set_sequences(sequences)

def _dump_sequences(self, message, key):
        """Inspect a new MHMessage and update sequences appropriately."""
        pending_sequences = message.get_sequences()
        all_sequences = self.get_sequences()
        for name, key_list in all_sequences.items():
            if name in pending_sequences:
                key_list.append(key)
            elif key in key_list:
                del key_list[key_list.index(key)]
        for sequence in pending_sequences:
            if sequence not in all_sequences:
                all_sequences[sequence] = [key]
        self.set_sequences(all_sequences)

class Babyl(_singlefileMailbox):
    """An Rmail-style Babyl mailbox."""

_special_labels = frozenset({'unseen', 'deleted', 'filed', 'answered',
                                 'forwarded', 'edited', 'resent'})

def __init__(self, path, factory=None, create=True):
        """Initialize a Babyl mailbox."""
        _singlefileMailbox.__init__(self, path, factory, create)
        self._labels = {}

def add(self, message):
        """Add message and return assigned key."""
        key = _singlefileMailbox.add(self, message)
        if isinstance(message, BabylMessage):
            self._labels[key] = message.get_labels()
        return key

def remove(self, key):
        """Remove the keyed message; raise KeyError if it doesn't exist."""
        _singlefileMailbox.remove(self, key)
        if key in self._labels:
            del self._labels[key]

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        _singlefileMailbox.__setitem__(self, key, message)
        if isinstance(message, BabylMessage):
            self._labels[key] = message.get_labels()

def get_message(self, key):
        """Return a Message representation or raise a KeyError."""
        start, stop = self._lookup(key)
        self._file.seek(start)
        self._file.readline()   # Skip b'1,' line specifying labels.
        original_headers = io.BytesIO()
        while True:
            line = self._file.readline()
            if line == b'*** EOOH ***' + linesep or not line:
                break
            original_headers.write(line.replace(linesep, b'\n'))
        visible_headers = io.BytesIO()
        while True:
            line = self._file.readline()
            if line == linesep or not line:
                break
            visible_headers.write(line.replace(linesep, b'\n'))
        # Read up to the stop, or to the end
        n = stop - self._file.tell()
        assert n >= 0
        body = self._file.read(n)
        body = body.replace(linesep, b'\n')
        msg = BabylMessage(original_headers.getvalue() + body)
        msg.set_visible(visible_headers.getvalue())
        if key in self._labels:
            msg.set_labels(self._labels[key])
        return msg

def get_bytes(self, key):
        """Return a string representation or raise a KeyError."""
        start, stop = self._lookup(key)
        self._file.seek(start)
        self._file.readline()   # Skip b'1,' line specifying labels.
        original_headers = io.BytesIO()
        while True:
            line = self._file.readline()
            if line == b'*** EOOH ***' + linesep or not line:
                break
            original_headers.write(line.replace(linesep, b'\n'))
        while True:
            line = self._file.readline()
            if line == linesep or not line:
                break
        headers = original_headers.getvalue()
        n = stop - self._file.tell()
        assert n >= 0
        data = self._file.read(n)
        data = data.replace(linesep, b'\n')
        return headers + data

def get_file(self, key):
        """Return a file-like representation or raise a KeyError."""
        return io.BytesIO(self.get_bytes(key).replace(b'\n', linesep))

def get_labels(self):
        """Return a list of user-defined labels in the mailbox."""
        self._lookup()
        labels = set()
        for label_list in self._labels.values():
            labels.update(label_list)
        labels.difference_update(self._special_labels)
        return list(labels)

def _generate_toc(self):
        """Generate key-to-(start, stop) table of contents."""
        starts, stops = [], []
        self._file.seek(0)
        next_pos = 0
        label_lists = []
        while True:
            line_pos = next_pos
            line = self._file.readline()
            next_pos = self._file.tell()
            if line == b'\037\014' + linesep:
                if len(stops) < len(starts):
                    stops.append(line_pos - len(linesep))
                starts.append(next_pos)
                labels = [label.strip() for label
                                        in self._file.readline()[1:].split(b',')
                                        if label.strip()]
                label_lists.append(labels)
            elif line == b'\037' or line == b'\037' + linesep:
                if len(stops) < len(starts):
                    stops.append(line_pos - len(linesep))
            elif not line:
                stops.append(line_pos - len(linesep))
                break
        self._toc = dict(enumerate(zip(starts, stops)))
        self._labels = dict(enumerate(label_lists))
        self._next_key = len(self._toc)
        self._file.seek(0, 2)
        self._file_length = self._file.tell()

def _pre_mailbox_hook(self, f):
        """Called before writing the mailbox to file f."""
        babyl = b'BABYL OPTIONS:' + linesep
        babyl += b'Version: 5' + linesep
        labels = self.get_labels()
        labels = (label.encode() for label in labels)
        babyl += b'Labels:' + b','.join(labels) + linesep
        babyl += b'\037'
        f.write(babyl)

def _pre_message_hook(self, f):
        """Called before writing each message to file f."""
        f.write(b'\014' + linesep)

def _post_message_hook(self, f):
        """Called after writing each message to file f."""
        f.write(linesep + b'\037')

def _install_message(self, message):
        """Write message contents and return (start, stop)."""
        start = self._file.tell()
        if isinstance(message, BabylMessage):
            special_labels = []
            labels = []
            for label in message.get_labels():
                if label in self._special_labels:
                    special_labels.append(label)
                else:
                    labels.append(label)
            self._file.write(b'1')
            for label in special_labels:
                self._file.write(b', ' + label.encode())
            self._file.write(b',,')
            for label in labels:
                self._file.write(b' ' + label.encode() + b',')
            self._file.write(linesep)
        else:
            self._file.write(b'1,,' + linesep)
        if isinstance(message, email.message.Message):
            orig_buffer = io.BytesIO()
            orig_generator = email.generator.BytesGenerator(orig_buffer, False, 0)
            orig_generator.flatten(message)
            orig_buffer.seek(0)
            while True:
                line = orig_buffer.readline()
                self._file.write(line.replace(b'\n', linesep))
                if line == b'\n' or not line:
                    break
            self._file.write(b'*** EOOH ***' + linesep)
            if isinstance(message, BabylMessage):
                vis_buffer = io.BytesIO()
                vis_generator = email.generator.BytesGenerator(vis_buffer, False, 0)
                vis_generator.flatten(message.get_visible())
                while True:
                    line = vis_buffer.readline()
                    self._file.write(line.replace(b'\n', linesep))
                    if line == b'\n' or not line:
                        break
            else:
                orig_buffer.seek(0)
                while True:
                    line = orig_buffer.readline()
                    self._file.write(line.replace(b'\n', linesep))
                    if line == b'\n' or not line:
                        break
            while True:
                buffer = orig_buffer.read(4096) # Buffer size is arbitrary.
                if not buffer:
                    break
                self._file.write(buffer.replace(b'\n', linesep))
        elif isinstance(message, (bytes, str, io.StringIO)):
            if isinstance(message, io.StringIO):
                warnings.warn("Use of StringIO input is deprecated, "
                    "use BytesIO instead", DeprecationWarning, 3)
                message = message.getvalue()
            if isinstance(message, str):
                message = self._string_to_bytes(message)
            body_start = message.find(b'\n\n') + 2
            if body_start - 2 != -1:
                self._file.write(message[:body_start].replace(b'\n', linesep))
                self._file.write(b'*** EOOH ***' + linesep)
                self._file.write(message[:body_start].replace(b'\n', linesep))
                self._file.write(message[body_start:].replace(b'\n', linesep))
            else:
                self._file.write(b'*** EOOH ***' + linesep + linesep)
                self._file.write(message.replace(b'\n', linesep))
        elif hasattr(message, 'readline'):
            if hasattr(message, 'buffer'):
                warnings.warn("Use of text mode files is deprecated, "
                    "use a binary mode file instead", DeprecationWarning, 3)
                message = message.buffer
            original_pos = message.tell()
            first_pass = True
            while True:
                line = message.readline()
                # Universal newline support.
                if line.endswith(b'\r\n'):
                    line = line[:-2] + b'\n'
                elif line.endswith(b'\r'):
                    line = line[:-1] + b'\n'
                self._file.write(line.replace(b'\n', linesep))
                if line == b'\n' or not line:
                    if first_pass:
                        first_pass = False
                        self._file.write(b'*** EOOH ***' + linesep)
                        message.seek(original_pos)
                    else:
                        break
            while True:
                line = message.readline()
                if not line:
                    break
                # Universal newline support.
                if line.endswith(b'\r\n'):
                    line = line[:-2] + linesep
                elif line.endswith(b'\r'):
                    line = line[:-1] + linesep
                elif line.endswith(b'\n'):
                    line = line[:-1] + linesep
                self._file.write(line)
        else:
            raise TypeError('Invalid message type: %s' % type(message))
        stop = self._file.tell()
        return (start, stop)

class Message(email.message.Message):
    """Message with mailbox-format-specific properties."""

def __init__(self, message=None):
        """Initialize a Message instance."""
        if isinstance(message, email.message.Message):
            self._become_message(copy.deepcopy(message))
            if isinstance(message, Message):
                message._explain_to(self)
        elif isinstance(message, bytes):
            self._become_message(email.message_from_bytes(message))
        elif isinstance(message, str):
            self._become_message(email.message_from_string(message))
        elif isinstance(message, io.TextIOWrapper):
            self._become_message(email.message_from_file(message))
        elif hasattr(message, "read"):
            self._become_message(email.message_from_binary_file(message))
        elif message is None:
            email.message.Message.__init__(self)
        else:
            raise TypeError('Invalid message type: %s' % type(message))

def _become_message(self, message):
        """Assume the non-format-specific state of message."""
        type_specific = getattr(message, '_type_specific_attributes', [])
        for name in message.__dict__:
            if name not in type_specific:
                self.__dict__[name] = message.__dict__[name]

def _explain_to(self, message):
        """Copy format-specific state to message insofar as possible."""
        if isinstance(message, Message):
            return  # There's nothing format-specific to explain.
        else:
            raise TypeError('Cannot convert to specified type')

class MaildirMessage(Message):
    """Message with Maildir-specific properties."""

_type_specific_attributes = ['_subdir', '_info', '_date']

def __init__(self, message=None):
        """Initialize a MaildirMessage instance."""
        self._subdir = 'new'
        self._info = ''
        self._date = time.time()
        Message.__init__(self, message)

def get_subdir(self):
        """Return 'new' or 'cur'."""
        return self._subdir

def set_subdir(self, subdir):
        """Set subdir to 'new' or 'cur'."""
        if subdir == 'new' or subdir == 'cur':
            self._subdir = subdir
        else:
            raise ValueError("subdir must be 'new' or 'cur': %s" % subdir)

def get_flags(self):
        """Return as a string the flags that are set."""
        if self._info.startswith('2,'):
            return self._info[2:]
        else:
            return ''

def set_flags(self, flags):
        """Set the given flags and unset all others."""
        self._info = '2,' + ''.join(sorted(flags))

def add_flag(self, flag):
        """Set the given flag(s) without changing others."""
        self.set_flags(''.join(set(self.get_flags()) | set(flag)))

def remove_flag(self, flag):
        """Unset the given string flag(s) without changing others."""
        if self.get_flags():
            self.set_flags(''.join(set(self.get_flags()) - set(flag)))

def get_date(self):
        """Return delivery date of message, in seconds since the epoch."""
        return self._date

def set_date(self, date):
        """Set delivery date of message, in seconds since the epoch."""
        try:
            self._date = float(date)
        except ValueError:
            raise TypeError("can't convert to float: %s" % date)

def get_info(self):
        """Get the message's "info" as a string."""
        return self._info

def set_info(self, info):
        """Set the message's "info" string."""
        if isinstance(info, str):
            self._info = info
        else:
            raise TypeError('info must be a string: %s' % type(info))

def _explain_to(self, message):
        """Copy Maildir-specific state to message insofar as possible."""
        if isinstance(message, MaildirMessage):
            message.set_flags(self.get_flags())
            message.set_subdir(self.get_subdir())
            message.set_date(self.get_date())
        elif isinstance(message, _mboxMMDFMessage):
            flags = set(self.get_flags())
            if 'S' in flags:
                message.add_flag('R')
            if self.get_subdir() == 'cur':
                message.add_flag('O')
            if 'T' in flags:
                message.add_flag('D')
            if 'F' in flags:
                message.add_flag('F')
            if 'R' in flags:
                message.add_flag('A')
            message.set_from('MAILER-DAEMON', time.gmtime(self.get_date()))
        elif isinstance(message, MHMessage):
            flags = set(self.get_flags())
            if 'S' not in flags:
                message.add_sequence('unseen')
            if 'R' in flags:
                message.add_sequence('replied')
            if 'F' in flags:
                message.add_sequence('flagged')
        elif isinstance(message, BabylMessage):
            flags = set(self.get_flags())
            if 'S' not in flags:
                message.add_label('unseen')
            if 'T' in flags:
                message.add_label('deleted')
            if 'R' in flags:
                message.add_label('answered')
            if 'P' in flags:
                message.add_label('forwarded')
        elif isinstance(message, Message):
            pass
        else:
            raise TypeError('Cannot convert to specified type: %s' %
                            type(message))

class _mboxMMDFMessage(Message):
    """Message with mbox- or MMDF-specific properties."""

_type_specific_attributes = ['_from']

def __init__(self, message=None):
        """Initialize an mboxMMDFMessage instance."""
        self.set_from('MAILER-DAEMON', True)
        if isinstance(message, email.message.Message):
            unixfrom = message.get_unixfrom()
            if unixfrom is not None and unixfrom.startswith('From '):
                self.set_from(unixfrom[5:])
        Message.__init__(self, message)

def get_from(self):
        """Return contents of "From " line."""
        return self._from

def set_from(self, from_, time_=None):
        """Set "From " line, formatting and appending time_ if specified."""
        if time_ is not None:
            if time_ is True:
                time_ = time.gmtime()
            from_ += ' ' + time.asctime(time_)
        self._from = from_

def get_flags(self):
        """Return as a string the flags that are set."""
        return self.get('Status', '') + self.get('X-Status', '')

def set_flags(self, flags):
        """Set the given flags and unset all others."""
        flags = set(flags)
        status_flags, xstatus_flags = '', ''
        for flag in ('R', 'O'):
            if flag in flags:
                status_flags += flag
                flags.remove(flag)
        for flag in ('D', 'F', 'A'):
            if flag in flags:
                xstatus_flags += flag
                flags.remove(flag)
        xstatus_flags += ''.join(sorted(flags))
        try:
            self.replace_header('Status', status_flags)
        except KeyError:
            self.add_header('Status', status_flags)
        try:
            self.replace_header('X-Status', xstatus_flags)
        except KeyError:
            self.add_header('X-Status', xstatus_flags)

def add_flag(self, flag):
        """Set the given flag(s) without changing others."""
        self.set_flags(''.join(set(self.get_flags()) | set(flag)))

def remove_flag(self, flag):
        """Unset the given string flag(s) without changing others."""
        if 'Status' in self or 'X-Status' in self:
            self.set_flags(''.join(set(self.get_flags()) - set(flag)))

def _explain_to(self, message):
        """Copy mbox- or MMDF-specific state to message insofar as possible."""
        if isinstance(message, MaildirMessage):
            flags = set(self.get_flags())
            if 'O' in flags:
                message.set_subdir('cur')
            if 'F' in flags:
                message.add_flag('F')
            if 'A' in flags:
                message.add_flag('R')
            if 'R' in flags:
                message.add_flag('S')
            if 'D' in flags:
                message.add_flag('T')
            del message['status']
            del message['x-status']
            maybe_date = ' '.join(self.get_from().split()[-5:])
            try:
                message.set_date(calendar.timegm(time.strptime(maybe_date,
                                                      '%a %b %d %H:%M:%S %Y')))
            except (ValueError, OverflowError):
                pass
        elif isinstance(message, _mboxMMDFMessage):
            message.set_flags(self.get_flags())
            message.set_from(self.get_from())
        elif isinstance(message, MHMessage):
            flags = set(self.get_flags())
            if 'R' not in flags:
                message.add_sequence('unseen')
            if 'A' in flags:
                message.add_sequence('replied')
            if 'F' in flags:
                message.add_sequence('flagged')
            del message['status']
            del message['x-status']
        elif isinstance(message, BabylMessage):
            flags = set(self.get_flags())
            if 'R' not in flags:
                message.add_label('unseen')
            if 'D' in flags:
                message.add_label('deleted')
            if 'A' in flags:
                message.add_label('answered')
            del message['status']
            del message['x-status']
        elif isinstance(message, Message):
            pass
        else:
            raise TypeError('Cannot convert to specified type: %s' %
                            type(message))

class mboxMessage(_mboxMMDFMessage):
    """Message with mbox-specific properties."""

class MHMessage(Message):
    """Message with MH-specific properties."""

_type_specific_attributes = ['_sequences']

def __init__(self, message=None):
        """Initialize an MHMessage instance."""
        self._sequences = []
        Message.__init__(self, message)

def get_sequences(self):
        """Return a list of sequences that include the message."""
        return self._sequences[:]

def set_sequences(self, sequences):
        """Set the list of sequences that include the message."""
        self._sequences = list(sequences)

def add_sequence(self, sequence):
        """Add sequence to list of sequences including the message."""
        if isinstance(sequence, str):
            if not sequence in self._sequences:
                self._sequences.append(sequence)
        else:
            raise TypeError('sequence type must be str: %s' % type(sequence))

def remove_sequence(self, sequence):
        """Remove sequence from the list of sequences including the message."""
        try:
            self._sequences.remove(sequence)
        except ValueError:
            pass

def _explain_to(self, message):
        """Copy MH-specific state to message insofar as possible."""
        if isinstance(message, MaildirMessage):
            sequences = set(self.get_sequences())
            if 'unseen' in sequences:
                message.set_subdir('cur')
            else:
                message.set_subdir('cur')
                message.add_flag('S')
            if 'flagged' in sequences:
                message.add_flag('F')
            if 'replied' in sequences:
                message.add_flag('R')
        elif isinstance(message, _mboxMMDFMessage):
            sequences = set(self.get_sequences())
            if 'unseen' not in sequences:
                message.add_flag('RO')
            else:
                message.add_flag('O')
            if 'flagged' in sequences:
                message.add_flag('F')
            if 'replied' in sequences:
                message.add_flag('A')
        elif isinstance(message, MHMessage):
            for sequence in self.get_sequences():
                message.add_sequence(sequence)
        elif isinstance(message, BabylMessage):
            sequences = set(self.get_sequences())
            if 'unseen' in sequences:
                message.add_label('unseen')
            if 'replied' in sequences:
                message.add_label('answered')
        elif isinstance(message, Message):
            pass
        else:
            raise TypeError('Cannot convert to specified type: %s' %
                            type(message))

class BabylMessage(Message):
    """Message with Babyl-specific properties."""

_type_specific_attributes = ['_labels', '_visible']

def __init__(self, message=None):
        """Initialize a BabylMessage instance."""
        self._labels = []
        self._visible = Message()
        Message.__init__(self, message)

def get_labels(self):
        """Return a list of labels on the message."""
        return self._labels[:]

def set_labels(self, labels):
        """Set the list of labels on the message."""
        self._labels = list(labels)

def add_label(self, label):
        """Add label to list of labels on the message."""
        if isinstance(label, str):
            if label not in self._labels:
                self._labels.append(label)
        else:
            raise TypeError('label must be a string: %s' % type(label))

def remove_label(self, label):
        """Remove label from the list of labels on the message."""
        try:
            self._labels.remove(label)
        except ValueError:
            pass

def get_visible(self):
        """Return a Message representation of visible headers."""
        return Message(self._visible)

def set_visible(self, visible):
        """Set the Message representation of visible headers."""
        self._visible = Message(visible)

def update_visible(self):
        """Update and/or sensibly generate a set of visible headers."""
        for header in self._visible.keys():
            if header in self:
                self._visible.replace_header(header, self[header])
            else:
                del self._visible[header]
        for header in ('Date', 'From', 'Reply-To', 'To', 'CC', 'Subject'):
            if header in self and header not in self._visible:
                self._visible[header] = self[header]

def _explain_to(self, message):
        """Copy Babyl-specific state to message insofar as possible."""
        if isinstance(message, MaildirMessage):
            labels = set(self.get_labels())
            if 'unseen' in labels:
                message.set_subdir('cur')
            else:
                message.set_subdir('cur')
                message.add_flag('S')
            if 'forwarded' in labels or 'resent' in labels:
                message.add_flag('P')
            if 'answered' in labels:
                message.add_flag('R')
            if 'deleted' in labels:
                message.add_flag('T')
        elif isinstance(message, _mboxMMDFMessage):
            labels = set(self.get_labels())
            if 'unseen' not in labels:
                message.add_flag('RO')
            else:
                message.add_flag('O')
            if 'deleted' in labels:
                message.add_flag('D')
            if 'answered' in labels:
                message.add_flag('A')
        elif isinstance(message, MHMessage):
            labels = set(self.get_labels())
            if 'unseen' in labels:
                message.add_sequence('unseen')
            if 'answered' in labels:
                message.add_sequence('replied')
        elif isinstance(message, BabylMessage):
            message.set_visible(self.get_visible())
            for label in self.get_labels():
                message.add_label(label)
        elif isinstance(message, Message):
            pass
        else:
            raise TypeError('Cannot convert to specified type: %s' %
                            type(message))

class MMDFMessage(_mboxMMDFMessage):
    """Message with MMDF-specific properties."""

class _ProxyFile:
    """A read-only wrapper of a file."""

def __init__(self, f, pos=None):
        """Initialize a _ProxyFile."""
        self._file = f
        if pos is None:
            self._pos = f.tell()
        else:
            self._pos = pos

def read(self, size=None):
        """Read bytes."""
        return self._read(size, self._file.read)

def read1(self, size=None):
        """Read bytes."""
        return self._read(size, self._file.read1)

def readline(self, size=None):
        """Read a line."""
        return self._read(size, self._file.readline)

def readlines(self, sizehint=None):
        """Read multiple lines."""
        result = []
        for line in self:
            result.append(line)
            if sizehint is not None:
                sizehint -= len(line)
                if sizehint <= 0:
                    break
        return result

def __iter__(self):
        """Iterate over lines."""
        while True:
            line = self.readline()
            if not line:
                return
            yield line

def tell(self):
        """Return the position."""
        return self._pos

def seek(self, offset, whence=0):
        """Change position."""
        if whence == 1:
            self._file.seek(self._pos)
        self._file.seek(offset, whence)
        self._pos = self._file.tell()

def close(self):
        """Close the file."""
        if hasattr(self, '_file'):
            try:
                if hasattr(self._file, 'close'):
                    self._file.close()
            finally:
                del self._file

def _read(self, size, read_method):
        """Read size bytes using read_method."""
        if size is None:
            size = -1
        self._file.seek(self._pos)
        result = read_method(size)
        self._pos = self._file.tell()
        return result

def __enter__(self):
        """Context management protocol support."""
        return self

def __exit__(self, *exc):
        self.close()

def readable(self):
        return self._file.readable()

def writable(self):
        return self._file.writable()

def seekable(self):
        return self._file.seekable()

def flush(self):
        return self._file.flush()

@property
    def closed(self):
        if not hasattr(self, '_file'):
            return True
        if not hasattr(self._file, 'closed'):
            return False
        return self._file.closed

class _PartialFile(_ProxyFile):
    """A read-only wrapper of part of a file."""

def __init__(self, f, start=None, stop=None):
        """Initialize a _PartialFile."""
        _ProxyFile.__init__(self, f, start)
        self._start = start
        self._stop = stop

def tell(self):
        """Return the position with respect to start."""
        return _ProxyFile.tell(self) - self._start

def seek(self, offset, whence=0):
        """Change position, possibly with respect to start or stop."""
        if whence == 0:
            self._pos = self._start
            whence = 1
        elif whence == 2:
            self._pos = self._stop
            whence = 1
        _ProxyFile.seek(self, offset, whence)

def _read(self, size, read_method):
        """Read size bytes using read_method, honoring start and stop."""
        remaining = self._stop - self._pos
        if remaining <= 0:
            return b''
        if size is None or size < 0 or size > remaining:
            size = remaining
        return _ProxyFile._read(self, size, read_method)

def close(self):
        # do *not* close the underlying file object for partial files,
        # since it's global to the mailbox object
        if hasattr(self, '_file'):
            del self._file

def _lock_file(f, dotlock=True):
    """Lock file f using lockf and dot locking."""
    dotlock_done = False
    try:
        if fcntl:
            try:
                fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
            except OSError as e:
                if e.errno in (errno.EAGAIN, errno.EACCES, errno.EROFS):
                    raise ExternalClashError('lockf: lock unavailable: %s' %
                                             f.name)
                else:
                    raise
        if dotlock:
            try:
                pre_lock = _create_temporary(f.name + '.lock')
                pre_lock.close()
            except OSError as e:
                if e.errno in (errno.EACCES, errno.EROFS):
                    return  # Without write access, just skip dotlocking.
                else:
                    raise
            try:
                try:
                    os.link(pre_lock.name, f.name + '.lock')
                    dotlock_done = True
                except (AttributeError, PermissionError):
                    os.rename(pre_lock.name, f.name + '.lock')
                    dotlock_done = True
                else:
                    os.unlink(pre_lock.name)
            except FileExistsError:
                os.remove(pre_lock.name)
                raise ExternalClashError('dot lock unavailable: %s' %
                                         f.name)
    except:
        if fcntl:
            fcntl.lockf(f, fcntl.LOCK_UN)
        if dotlock_done:
            os.remove(f.name + '.lock')
        raise

def _unlock_file(f):
    """Unlock file f using lockf and dot locking."""
    if fcntl:
        fcntl.lockf(f, fcntl.LOCK_UN)
    if os.path.exists(f.name + '.lock'):
        os.remove(f.name + '.lock')

def _create_carefully(path):
    """Create a file if it doesn't exist and open for reading and writing."""
    fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_RDWR, 0o666)
    try:
        return open(path, 'rb+')
    finally:
        os.close(fd)

def _create_temporary(path):
    """Create a temp file based on path and open for reading and writing."""
    return _create_carefully('%s.%s.%s.%s' % (path, int(time.time()),
                                              socket.gethostname(),
                                              os.getpid()))

def _sync_flush(f):
    """Ensure changes to file f are physically on disk."""
    f.flush()
    if hasattr(os, 'fsync'):
        os.fsync(f.fileno())

def _sync_close(f):
    """Close file f, ensuring all changes are physically on disk."""
    _sync_flush(f)
    f.close()

class Error(Exception):
    """Raised for module-specific errors."""

class NoSuchMailboxError(Error):
    """The specified mailbox does not exist and won't be created."""

class NotEmptyError(Error):
    """The specified mailbox is not empty and deletion was requested."""

class ExternalClashError(Error):
    """Another process caused an action to fail."""

class FormatError(Error):
    """A file appears to have an invalid format."""

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