1 files changed, 44 insertions, 0 deletions
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
+