helper: move guess_mimetype into its own file

4 files changed, 48 insertions, 44 deletions

diff --git a/alot/db/message.py b/alot/db/message.py
index 01d7c7f1..f737721c 100644
--- a/alot/db/message.py
+++ b/alot/db/message.py
@@ -17,9 +17,9 @@ from urwid.util import detected_encoding
 from ..mail.attachment import Attachment
 from ..mail.policy     import p as policy
 from .. import crypto
-from .. import helper
 from ..errors import GPGProblem
 from ..settings.const import settings
+from ..utils.magic   import guess_mimetype
 from ..utils.mailcap import MailcapHandler
 
 charset.add_charset('utf-8', charset.QP, charset.QP, 'utf-8')
@@ -262,7 +262,7 @@ class _MimeTree:
             # replace underspecified mime description by a better guess
             if ctype in ['octet/stream', 'application/octet-stream',
                          'application/octetstream']:
-                ctype = helper.guess_mimetype(self._part.get_content())
+                ctype = guess_mimetype(self._part.get_content())
                 logging.debug('Overriding octet-stream content type to %s', ctype)
 
             maintype, _, subtype = ctype.partition('/')
diff --git a/alot/helper.py b/alot/helper.py
index 08df3667..43732b24 100644
--- a/alot/helper.py
+++ b/alot/helper.py
@@ -6,12 +6,9 @@
 from collections import deque
 import logging
 import os
-import re
 import shlex
 import email
 
-import magic
-
 
 def split_commandline(s):
     """
@@ -120,43 +117,6 @@ def shorten_author_string(authors_string, maxlength):
     authorsstring = ', '.join(authors_chain)
     return authorsstring
 
-
-def guess_mimetype(blob):
-    """
-    uses file magic to determine the mime-type of the given data blob.
-
-    :param blob: file content as read by file.read()
-    :type blob: data
-    :returns: mime-type, falls back to 'application/octet-stream'
-    :rtype: str
-    """
-    mimetype = 'application/octet-stream'
-    # this is a bit of a hack to support different versions of python magic.
-    # Hopefully at some point this will no longer be necessary
-    #
-    # the version with open() is the bindings shipped with the file source from
-    # http://darwinsys.com/file/ - this is what is used by the python-magic
-    # package on Debian/Ubuntu. However, it is not available on pypi/via pip.
-    #
-    # the version with from_buffer() is available at
-    # https://github.com/ahupp/python-magic and directly installable via pip.
-    #
-    # for more detail see https://github.com/pazz/alot/pull/588
-    if hasattr(magic, 'open'):
-        m = magic.open(magic.MAGIC_MIME_TYPE)
-        m.load()
-        magictype = m.buffer(blob)
-    elif hasattr(magic, 'from_buffer'):
-        # cf. issue #841
-        magictype = magic.from_buffer(blob, mime=True) or magictype
-    else:
-        raise Exception('Unknown magic API')
-
-    # libmagic does not always return proper mimetype strings, cf. issue #459
-    if re.match(r'\w+\/\w+', magictype):
-        mimetype = magictype
-    return mimetype
-
 def shell_quote(text):
     """Escape the given text for passing it to the shell for interpretation.
     The resulting string will be parsed into one "word" (in the sense used in
diff --git a/alot/mail/envelope.py b/alot/mail/envelope.py
index d3cace18..0a616a57 100644
--- a/alot/mail/envelope.py
+++ b/alot/mail/envelope.py
@@ -17,10 +17,10 @@ from . import headers as HDR
 
 from .attachment import Attachment
 from .. import __version__
-from .. import helper
 from .. import crypto
 from ..settings.const import settings
 from ..errors import GPGProblem, GPGCode
+from ..utils.magic   import guess_mimetype
 
 charset.add_charset('utf-8', charset.QP, charset.QP, 'utf-8')
 
@@ -239,7 +239,7 @@ class Envelope:
         with open(path, 'rb') as f:
             data = f.read()
 
-        ctype = helper.guess_mimetype(data)
+        ctype = guess_mimetype(data)
 
         params = []
 
diff --git a/alot/utils/magic.py b/alot/utils/magic.py
new file mode 100644
index 00000000..b6bbcfb2
--- /dev/null
+++ b/alot/utils/magic.py
@@ -0,0 +1,44 @@
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+
+import re
+
+import magic
+
+
+def guess_mimetype(blob):
+    """
+    uses file magic to determine the mime-type of the given data blob.
+
+    :param blob: file content as read by file.read()
+    :type blob: data
+    :returns: mime-type, falls back to 'application/octet-stream'
+    :rtype: str
+    """
+    mimetype = 'application/octet-stream'
+    # this is a bit of a hack to support different versions of python magic.
+    # Hopefully at some point this will no longer be necessary
+    #
+    # the version with open() is the bindings shipped with the file source from
+    # http://darwinsys.com/file/ - this is what is used by the python-magic
+    # package on Debian/Ubuntu. However, it is not available on pypi/via pip.
+    #
+    # the version with from_buffer() is available at
+    # https://github.com/ahupp/python-magic and directly installable via pip.
+    #
+    # for more detail see https://github.com/pazz/alot/pull/588
+    if hasattr(magic, 'open'):
+        m = magic.open(magic.MAGIC_MIME_TYPE)
+        m.load()
+        magictype = m.buffer(blob)
+    elif hasattr(magic, 'from_buffer'):
+        # cf. issue #841
+        magictype = magic.from_buffer(blob, mime=True) or magictype
+    else:
+        raise Exception('Unknown magic API')
+
+    # libmagic does not always return proper mimetype strings, cf. issue #459
+    if re.match(r'\w+\/\w+', magictype):
+        mimetype = magictype
+    return mimetype
+