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 dd86389..112ebb6 100644
--- a/magic/__init__.py
+++ b/magic/__init__.py
@@ -81,6 +81,13 @@ 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):
@@ -254,6 +261,10 @@ _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_load = libmagic.magic_load
 _magic_load.restype = c_int
diff --git a/test/test.py b/test/test.py
index c6e2d9c..aa24e5f 100755
--- a/test/test.py
+++ b/test/test.py
@@ -38,6 +38,12 @@ class MagicTest(unittest.TestCase):
         b = b'#!/usr/bin/env python\nprint("foo")'
         self.assertEqual("text/x-python", m.from_buffer(b))
 
+
+    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'))
         shutil.copyfile(os.path.join(MagicTest.TESTDATA_DIR, 'lambda'), dest)