1  # Copyright (C) 2001-2007 Python Software Foundation
       2  # Author: Anthony Baxter
       3  # Contact: email-sig@python.org
       4  
       5  """Class representing audio/* type MIME documents."""
       6  
       7  __all__ = ['MIMEAudio']
       8  
       9  from io import BytesIO
      10  from email import encoders
      11  from email.mime.nonmultipart import MIMENonMultipart
      12  
      13  
      14  class ESC[4;38;5;81mMIMEAudio(ESC[4;38;5;149mMIMENonMultipart):
      15      """Class for generating audio/* MIME documents."""
      16  
      17      def __init__(self, _audiodata, _subtype=None,
      18                   _encoder=encoders.encode_base64, *, policy=None, **_params):
      19          """Create an audio/* type MIME document.
      20  
      21          _audiodata contains the bytes for the raw audio data.  If this data
      22          can be decoded as au, wav, aiff, or aifc, then the
      23          subtype will be automatically included in the Content-Type header.
      24          Otherwise, you can specify  the specific audio subtype via the
      25          _subtype parameter.  If _subtype is not given, and no subtype can be
      26          guessed, a TypeError is raised.
      27  
      28          _encoder is a function which will perform the actual encoding for
      29          transport of the image data.  It takes one argument, which is this
      30          Image instance.  It should use get_payload() and set_payload() to
      31          change the payload to the encoded form.  It should also add any
      32          Content-Transfer-Encoding or other headers to the message as
      33          necessary.  The default encoding is Base64.
      34  
      35          Any additional keyword arguments are passed to the base class
      36          constructor, which turns them into parameters on the Content-Type
      37          header.
      38          """
      39          if _subtype is None:
      40              _subtype = _what(_audiodata)
      41          if _subtype is None:
      42              raise TypeError('Could not find audio MIME subtype')
      43          MIMENonMultipart.__init__(self, 'audio', _subtype, policy=policy,
      44                                    **_params)
      45          self.set_payload(_audiodata)
      46          _encoder(self)
      47  
      48  
      49  _rules = []
      50  
      51  
      52  # Originally from the sndhdr module.
      53  #
      54  # There are others in sndhdr that don't have MIME types. :(
      55  # Additional ones to be added to sndhdr? midi, mp3, realaudio, wma??
      56  def _what(data):
      57      # Try to identify a sound file type.
      58      #
      59      # sndhdr.what() had a pretty cruddy interface, unfortunately.  This is why
      60      # we re-do it here.  It would be easier to reverse engineer the Unix 'file'
      61      # command and use the standard 'magic' file, as shipped with a modern Unix.
      62      hdr = data[:512]
      63      fakefile = BytesIO(hdr)
      64      for testfn in _rules:
      65          if res := testfn(hdr, fakefile):
      66              return res
      67      else:
      68          return None
      69  
      70  
      71  def rule(rulefunc):
      72      _rules.append(rulefunc)
      73      return rulefunc
      74  
      75  
      76  @rule
      77  def _aiff(h, f):
      78      if not h.startswith(b'FORM'):
      79          return None
      80      if h[8:12] in {b'AIFC', b'AIFF'}:
      81          return 'x-aiff'
      82      else:
      83          return None
      84  
      85  
      86  @rule
      87  def _au(h, f):
      88      if h.startswith(b'.snd'):
      89          return 'basic'
      90      else:
      91          return None
      92  
      93  
      94  @rule
      95  def _wav(h, f):
      96      # 'RIFF' <len> 'WAVE' 'fmt ' <len>
      97      if not h.startswith(b'RIFF') or h[8:12] != b'WAVE' or h[12:16] != b'fmt ':
      98          return None
      99      else:
     100          return "x-wav"