add from_open_file to match libmagic binding featureset

2 files changed, 17 insertions, 0 deletions

diff --git a/magic/__init__.py b/magic/__init__.py
index 3b351e2..fae6620 100644
--- a/magic/__init__.py
+++ b/magic/__init__.py
@@ -104,6 +104,13 @@ class Magic:
             except MagicException as e:
                 return self._handle509Bug(e)
 
+    def from_open_file(self, open_file):
+        with self.lock:
+            try:
+                return maybe_decode(magic_descriptor(self.cookie, open_file.fileno()))
+            except MagicException as e:
+                return self._handle509Bug(e)
+
     def from_file(self, filename):
         # raise FileNotFoundException or IOError if the file does not exist
         with open(filename):
@@ -318,6 +325,10 @@ _magic_buffer.errcheck = errorcheck_null
 def magic_buffer(cookie, buf):
     return _magic_buffer(cookie, buf, len(buf))
 
+magic_descriptor = libmagic.magic_descriptor
+magic_descriptor.restype = c_char_p
+magic_descriptor.argtypes = [magic_t, c_int]
+magic_descriptor.errcheck = errorcheck_null
 
 _magic_descriptor = libmagic.magic_descriptor
 _magic_descriptor.restype = c_char_p
diff --git a/test/test.py b/test/test.py
index 3097e6e..2865a66 100755
--- a/test/test.py
+++ b/test/test.py
@@ -74,6 +74,12 @@ class MagicTest(unittest.TestCase):
             in ("text/x-python", "text/x-script.python"))
 
 
+
+    def test_open_file(self):
+        m = magic.Magic(mime=True)
+        with open(os.path.join(self.TESTDATA_DIR, "test.pdf")) as f:
+            self.assertEqual("application/pdf", m.from_open_file(f))
+
     def test_mime_types(self):
         dest = os.path.join(MagicTest.TESTDATA_DIR,
                             b'\xce\xbb'.decode('utf-8'))