#9124: mailbox now accepts binary input and uses binary internally

Although this patch contains API changes and is rather weighty for an
RC phase, the mailbox module was essentially unusable without the patch
since it would produce UnicodeErrors when handling non-ascii input
at arbitrary and somewhat mysterious places, and any non-trivial amount
of email processing will encounter messages with non-ascii bytes.
The release manager approved the patch application.

The changes allow binary input, and reject non-ASCII string input early
with a useful message instead of failing mysteriously later.  Binary
is used internally for reading and writing the mailbox files.  StringIO
and Text file input are deprecated.

Initial patch by Victor Stinner, validated and expanded by R. David Murray.

1 files changed, 208 insertions, 119 deletions

diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 520463a..53f4159 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -15,6 +15,7 @@ import calendar
 import socket
 import errno
 import copy
+import warnings
 import email
 import email.message
 import email.generator
@@ -31,6 +32,8 @@ __all__ = [ 'Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF',
             'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage',
             'BabylMessage', 'MMDFMessage']
 
+linesep = os.linesep.encode('ascii')
+
 class Mailbox:
     """A group of messages in a particular place."""
 
@@ -80,7 +83,14 @@ class Mailbox:
         raise NotImplementedError('Method must be implemented by subclass')
 
     def get_string(self, key):
-        """Return a string representation or raise a KeyError."""
+        """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):
@@ -186,31 +196,55 @@ class Mailbox:
         """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")
+
     def _dump_message(self, message, target, mangle_from_=False):
-        # This assumes the target file is open in *text* mode with the
-        # desired encoding and newline setting.
+        # This assumes the target file is open in binary mode.
         """Dump message contents to target file."""
         if isinstance(message, email.message.Message):
-            buffer = io.StringIO()
-            gen = email.generator.Generator(buffer, mangle_from_, 0)
+            buffer = io.BytesIO()
+            gen = email.generator.BytesGenerator(buffer, mangle_from_, 0)
             gen.flatten(message)
             buffer.seek(0)
             data = buffer.read()
-            ##data = data.replace('\n', os.linesep)
+            data = data.replace(b'\n', linesep)
             target.write(data)
-        elif isinstance(message, str):
+        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('\nFrom ', '\n>From ')
-            ##message = message.replace('\n', os.linesep)
+                message = message.replace(b'\nFrom ', b'\n>From ')
+            message = message.replace(b'\n', linesep)
             target.write(message)
         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
             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('From '):
-                    line = '>From ' + line[5:]
-                ##line = line.replace('\n', os.linesep)
+                if mangle_from_ and line.startswith(b'From '):
+                    line = b'>From ' + line[5:]
+                line = line.replace(b'\n', linesep)
                 target.write(line)
         else:
             raise TypeError('Invalid message type: %s' % type(message))
@@ -319,7 +353,7 @@ class Maildir(Mailbox):
     def get_message(self, key):
         """Return a Message representation or raise a KeyError."""
         subpath = self._lookup(key)
-        f = open(os.path.join(self._path, subpath), 'r', newline='')
+        f = open(os.path.join(self._path, subpath), 'rb')
         try:
             if self._factory:
                 msg = self._factory(f)
@@ -334,17 +368,17 @@ class Maildir(Mailbox):
         msg.set_date(os.path.getmtime(os.path.join(self._path, subpath)))
         return msg
 
-    def get_string(self, key):
-        """Return a string representation or raise a KeyError."""
-        f = open(os.path.join(self._path, self._lookup(key)), 'r', newline='')
+    def get_bytes(self, key):
+        """Return a bytes representation or raise a KeyError."""
+        f = open(os.path.join(self._path, self._lookup(key)), 'rb')
         try:
-            return f.read()
+            return f.read().replace(linesep, b'\n')
         finally:
             f.close()
 
     def get_file(self, key):
         """Return a file-like representation or raise a KeyError."""
-        f = open(os.path.join(self._path, self._lookup(key)), 'r', newline='')
+        f = open(os.path.join(self._path, self._lookup(key)), 'rb')
         return _ProxyFile(f)
 
     def iterkeys(self):
@@ -534,15 +568,15 @@ class _singlefileMailbox(Mailbox):
         """Initialize a single-file mailbox."""
         Mailbox.__init__(self, path, factory, create)
         try:
-            f = open(self._path, 'r+', newline='')
+            f = open(self._path, 'rb+')
         except IOError as e:
             if e.errno == errno.ENOENT:
                 if create:
-                    f = open(self._path, 'w+', newline='')
+                    f = open(self._path, 'wb+')
                 else:
                     raise NoSuchMailboxError(self._path)
             elif e.errno == errno.EACCES:
-                f = open(self._path, 'r', newline='')
+                f = open(self._path, 'rb')
             else:
                 raise
         self._file = f
@@ -708,20 +742,25 @@ class _mboxMMDF(_singlefileMailbox):
         """Return a Message representation or raise a KeyError."""
         start, stop = self._lookup(key)
         self._file.seek(start)
-        from_line = self._file.readline().replace(os.linesep, '')
+        from_line = self._file.readline().replace(linesep, b'')
         string = self._file.read(stop - self._file.tell())
-        msg = self._message_factory(string.replace(os.linesep, '\n'))
-        msg.set_from(from_line[5:])
+        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(os.linesep, '\n')
+        return string.replace(linesep, b'\n')
 
     def get_file(self, key, from_=False):
         """Return a file-like representation or raise a KeyError."""
@@ -734,22 +773,27 @@ class _mboxMMDF(_singlefileMailbox):
     def _install_message(self, message):
         """Format a message and blindly write to self._file."""
         from_line = None
-        if isinstance(message, str) and message.startswith('From '):
-            newline = message.find('\n')
+        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 = ''
+                message = b''
         elif isinstance(message, _mboxMMDFMessage):
-            from_line = 'From ' + message.get_from()
+            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 = 'From MAILER-DAEMON %s' % time.asctime(time.gmtime())
+            from_line = b'From MAILER-DAEMON ' + time.asctime(time.gmtime()).encode()
         start = self._file.tell()
-        self._file.write(from_line + os.linesep)
+        self._file.write(from_line + linesep)
         self._dump_message(message, self._file, self._mangle_from_)
         stop = self._file.tell()
         return (start, stop)
@@ -768,7 +812,7 @@ class mbox(_mboxMMDF):
     def _pre_message_hook(self, f):
         """Called before writing each message to file f."""
         if f.tell() != 0:
-            f.write(os.linesep)
+            f.write(linesep)
 
     def _generate_toc(self):
         """Generate key-to-(start, stop) table of contents."""
@@ -777,9 +821,9 @@ class mbox(_mboxMMDF):
         while True:
             line_pos = self._file.tell()
             line = self._file.readline()
-            if line.startswith('From '):
+            if line.startswith(b'From '):
                 if len(stops) < len(starts):
-                    stops.append(line_pos - len(os.linesep))
+                    stops.append(line_pos - len(linesep))
                 starts.append(line_pos)
             elif not line:
                 stops.append(line_pos)
@@ -799,11 +843,11 @@ class MMDF(_mboxMMDF):
 
     def _pre_message_hook(self, f):
         """Called before writing each message to file f."""
-        f.write('\001\001\001\001' + os.linesep)
+        f.write(b'\001\001\001\001' + linesep)
 
     def _post_message_hook(self, f):
         """Called after writing each message to file f."""
-        f.write(os.linesep + '\001\001\001\001' + os.linesep)
+        f.write(linesep + b'\001\001\001\001' + linesep)
 
     def _generate_toc(self):
         """Generate key-to-(start, stop) table of contents."""
@@ -814,14 +858,14 @@ class MMDF(_mboxMMDF):
             line_pos = next_pos
             line = self._file.readline()
             next_pos = self._file.tell()
-            if line.startswith('\001\001\001\001' + os.linesep):
+            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 == '\001\001\001\001' + os.linesep:
-                        stops.append(line_pos - len(os.linesep))
+                    if line == b'\001\001\001\001' + linesep:
+                        stops.append(line_pos - len(linesep))
                         break
                     elif not line:
                         stops.append(line_pos)
@@ -890,7 +934,7 @@ class MH(Mailbox):
         """Replace the keyed message; raise KeyError if it doesn't exist."""
         path = os.path.join(self._path, str(key))
         try:
-            f = open(path, 'r+', newline='')
+            f = open(path, 'rb+')
         except IOError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
@@ -914,9 +958,9 @@ class MH(Mailbox):
         """Return a Message representation or raise a KeyError."""
         try:
             if self._locked:
-                f = open(os.path.join(self._path, str(key)), 'r+', newline='')
+                f = open(os.path.join(self._path, str(key)), 'rb+')
             else:
-                f = open(os.path.join(self._path, str(key)), 'r', newline='')
+                f = open(os.path.join(self._path, str(key)), 'rb')
         except IOError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
@@ -937,13 +981,13 @@ class MH(Mailbox):
                 msg.add_sequence(name)
         return msg
 
-    def get_string(self, key):
-        """Return a string representation or raise a KeyError."""
+    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)), 'r+', newline='')
+                f = open(os.path.join(self._path, str(key)), 'rb+')
             else:
-                f = open(os.path.join(self._path, str(key)), 'r', newline='')
+                f = open(os.path.join(self._path, str(key)), 'rb')
         except IOError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
@@ -953,7 +997,7 @@ class MH(Mailbox):
             if self._locked:
                 _lock_file(f)
             try:
-                return f.read()
+                return f.read().replace(linesep, b'\n')
             finally:
                 if self._locked:
                     _unlock_file(f)
@@ -963,7 +1007,7 @@ class MH(Mailbox):
     def get_file(self, key):
         """Return a file-like representation or raise a KeyError."""
         try:
-            f = open(os.path.join(self._path, str(key)), 'r', newline='')
+            f = open(os.path.join(self._path, str(key)), 'rb')
         except IOError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
@@ -1041,7 +1085,7 @@ class MH(Mailbox):
     def get_sequences(self):
         """Return a name-to-key-list dictionary to define each sequence."""
         results = {}
-        f = open(os.path.join(self._path, '.mh_sequences'), 'r', newline='')
+        f = open(os.path.join(self._path, '.mh_sequences'), 'r')
         try:
             all_keys = set(self.keys())
             for line in f:
@@ -1067,13 +1111,13 @@ class MH(Mailbox):
 
     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+', newline='')
+        f = open(os.path.join(self._path, '.mh_sequences'), 'r+')
         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('%s:' % name)
+                f.write(name + ':')
                 prev = None
                 completing = False
                 for key in sorted(set(keys)):
@@ -1168,50 +1212,55 @@ class Babyl(_singlefileMailbox):
         """Return a Message representation or raise a KeyError."""
         start, stop = self._lookup(key)
         self._file.seek(start)
-        self._file.readline()   # Skip '1,' line specifying labels.
-        original_headers = io.StringIO()
+        self._file.readline()   # Skip b'1,' line specifying labels.
+        original_headers = io.BytesIO()
         while True:
             line = self._file.readline()
-            if line == '*** EOOH ***' + os.linesep or not line:
+            if line == b'*** EOOH ***' + linesep or not line:
                 break
-            original_headers.write(line.replace(os.linesep, '\n'))
-        visible_headers = io.StringIO()
+            original_headers.write(line.replace(linesep, b'\n'))
+        visible_headers = io.BytesIO()
         while True:
             line = self._file.readline()
-            if line == os.linesep or not line:
+            if line == linesep or not line:
                 break
-            visible_headers.write(line.replace(os.linesep, '\n'))
-        body = self._file.read(stop - self._file.tell()).replace(os.linesep,
-                                                                 '\n')
+            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_string(self, key):
+    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 '1,' line specifying labels.
-        original_headers = io.StringIO()
+        self._file.readline()   # Skip b'1,' line specifying labels.
+        original_headers = io.BytesIO()
         while True:
             line = self._file.readline()
-            if line == '*** EOOH ***' + os.linesep or not line:
+            if line == b'*** EOOH ***' + linesep or not line:
                 break
-            original_headers.write(line.replace(os.linesep, '\n'))
+            original_headers.write(line.replace(linesep, b'\n'))
         while True:
             line = self._file.readline()
-            if line == os.linesep or not line:
+            if line == linesep or not line:
                 break
-        return original_headers.getvalue() + \
-               self._file.read(stop - self._file.tell()).replace(os.linesep,
-                                                                 '\n')
+        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.StringIO(self.get_string(key).replace('\n',
-                                                              os.linesep))
+        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."""
@@ -1232,19 +1281,19 @@ class Babyl(_singlefileMailbox):
             line_pos = next_pos
             line = self._file.readline()
             next_pos = self._file.tell()
-            if line == '\037\014' + os.linesep:
+            if line == b'\037\014' + linesep:
                 if len(stops) < len(starts):
-                    stops.append(line_pos - len(os.linesep))
+                    stops.append(line_pos - len(linesep))
                 starts.append(next_pos)
                 labels = [label.strip() for label
-                                        in self._file.readline()[1:].split(',')
+                                        in self._file.readline()[1:].split(b',')
                                         if label.strip()]
                 label_lists.append(labels)
-            elif line == '\037' or line == '\037' + os.linesep:
+            elif line == b'\037' or line == b'\037' + linesep:
                 if len(stops) < len(starts):
-                    stops.append(line_pos - len(os.linesep))
+                    stops.append(line_pos - len(linesep))
             elif not line:
-                stops.append(line_pos - len(os.linesep))
+                stops.append(line_pos - len(linesep))
                 break
         self._toc = dict(enumerate(zip(starts, stops)))
         self._labels = dict(enumerate(label_lists))
@@ -1254,17 +1303,21 @@ class Babyl(_singlefileMailbox):
 
     def _pre_mailbox_hook(self, f):
         """Called before writing the mailbox to file f."""
-        f.write('BABYL OPTIONS:%sVersion: 5%sLabels:%s%s\037' %
-                (os.linesep, os.linesep, ','.join(self.get_labels()),
-                 os.linesep))
+        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('\014' + os.linesep)
+        f.write(b'\014' + linesep)
 
     def _post_message_hook(self, f):
         """Called after writing each message to file f."""
-        f.write(os.linesep + '\037')
+        f.write(linesep + b'\037')
 
     def _install_message(self, message):
         """Write message contents and return (start, stop)."""
@@ -1277,68 +1330,80 @@ class Babyl(_singlefileMailbox):
                     special_labels.append(label)
                 else:
                     labels.append(label)
-            self._file.write('1')
+            self._file.write(b'1')
             for label in special_labels:
-                self._file.write(', ' + label)
-            self._file.write(',,')
+                self._file.write(b', ' + label.encode())
+            self._file.write(b',,')
             for label in labels:
-                self._file.write(' ' + label + ',')
-            self._file.write(os.linesep)
+                self._file.write(b' ' + label.encode() + b',')
+            self._file.write(linesep)
         else:
-            self._file.write('1,,' + os.linesep)
+            self._file.write(b'1,,' + linesep)
         if isinstance(message, email.message.Message):
-            orig_buffer = io.StringIO()
-            orig_generator = email.generator.Generator(orig_buffer, False, 0)
+            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('\n', os.linesep))
-                if line == '\n' or not line:
+                self._file.write(line.replace(b'\n', linesep))
+                if line == b'\n' or not line:
                     break
-            self._file.write('*** EOOH ***' + os.linesep)
+            self._file.write(b'*** EOOH ***' + linesep)
             if isinstance(message, BabylMessage):
-                vis_buffer = io.StringIO()
-                vis_generator = email.generator.Generator(vis_buffer, False, 0)
+                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('\n', os.linesep))
-                    if line == '\n' or not line:
+                    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('\n', os.linesep))
-                    if line == '\n' or not line:
+                    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('\n', os.linesep))
-        elif isinstance(message, str):
-            body_start = message.find('\n\n') + 2
+                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('\n',
-                                                              os.linesep))
-                self._file.write('*** EOOH ***' + os.linesep)
-                self._file.write(message[:body_start].replace('\n',
-                                                              os.linesep))
-                self._file.write(message[body_start:].replace('\n',
-                                                              os.linesep))
+                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('*** EOOH ***' + os.linesep + os.linesep)
-                self._file.write(message.replace('\n', os.linesep))
+                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()
-                self._file.write(line.replace('\n', os.linesep))
-                if line == '\n' or not line:
-                    self._file.write('*** EOOH ***' + os.linesep)
+                # 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:
+                    self._file.write(b'*** EOOH ***' + linesep)
                     if first_pass:
                         first_pass = False
                         message.seek(original_pos)
@@ -1348,7 +1413,7 @@ class Babyl(_singlefileMailbox):
                 buffer = message.read(4096)     # Buffer size is arbitrary.
                 if not buffer:
                     break
-                self._file.write(buffer.replace('\n', os.linesep))
+                self._file.write(buffer.replace(b'\n', linesep))
         else:
             raise TypeError('Invalid message type: %s' % type(message))
         stop = self._file.tell()
@@ -1364,10 +1429,14 @@ class 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 hasattr(message, "read"):
+        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:
@@ -1631,7 +1700,7 @@ class MHMessage(Message):
             if not sequence in self._sequences:
                 self._sequences.append(sequence)
         else:
-            raise TypeError('sequence must be a string: %s' % type(sequence))
+            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."""
@@ -1791,6 +1860,10 @@ class _ProxyFile:
         """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)
@@ -1847,6 +1920,22 @@ class _ProxyFile:
     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):
+        return self._file.closed
+
 
 class _PartialFile(_ProxyFile):
     """A read-only wrapper of part of a file."""
@@ -1875,7 +1964,7 @@ class _PartialFile(_ProxyFile):
         """Read size bytes using read_method, honoring start and stop."""
         remaining = self._stop - self._pos
         if remaining <= 0:
-            return ''
+            return b''
         if size is None or size < 0 or size > remaining:
             size = remaining
         return _ProxyFile._read(self, size, read_method)
@@ -1942,7 +2031,7 @@ 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, 'r+', newline='')
+        return open(path, 'rb+')
     finally:
         os.close(fd)