Merge pull request #2 into main

Author: Benjamin Moody

src/plibflac/_decoder.py

@@ -130,6 +130,7 @@ def open(self):
         has already been opened, this method does nothing.
         """
         if not self._opened:
+            self._original_raw_pos = None
             try:
                 if isinstance(self._fileobj, io.FileIO):
                     fd = self._fileobj.fileno()
@@ -138,7 +139,12 @@ def open(self):
                       and isinstance(self._fileobj.raw, io.FileIO)
                       and self._fileobj.seekable()):
                     fd = self._fileobj.fileno()
-                    self._fileobj.seek(0, io.SEEK_CUR)
+                    # Set the raw stream position (where we will begin
+                    # decoding) to the current buffered stream
+                    # position.  Save the original raw stream position
+                    # for later use.
+                    self._original_raw_pos = self._fileobj.raw.tell()
+                    self._fileobj.raw.seek(self._fileobj.tell())
                 else:
                     fd = -1
             except OSError:
@@ -168,6 +174,16 @@ def close(self):
             if self._opened:
                 self._opened = False
                 self._decoder.close()
+                if self._original_raw_pos is not None:
+                    # Set the buffered stream position equal to the
+                    # current raw stream position (where we finished
+                    # decoding).  In order to ensure the internal
+                    # state of the BufferedReader is consistent, we
+                    # must first restore the raw stream to the
+                    # position it had originally.
+                    final_pos = self._fileobj.raw.tell()
+                    self._fileobj.raw.seek(self._original_raw_pos)
+                    self._fileobj.seek(final_pos)
         finally:
             if self._closefile:
                 self._closefile = False

tests/test_decoder.py

@@ -54,6 +54,40 @@ def test_read_fileobj(self):
             with plibflac.Decoder(fileobj) as decoder:
                 self._test_read_sequential(decoder)
 
+    def test_read_buffered(self):
+        """
+        Test reading from a buffered file object.
+        """
+        with open(self.data_path('100s.flac'), 'rb') as fileobj:
+            # Read the first few bytes of the file, then rewind.
+            # Decoder should start reading at the current position in
+            # the buffered stream, not at the underlying file
+            # descriptor position.
+            fileobj.read(50)
+            fileobj.seek(0)
+            with plibflac.Decoder(fileobj) as decoder:
+                self._test_read_sequential(decoder)
+
+        with open(self.data_path('100s.flac'), 'rb') as fileobj:
+            # Check that buffered file object is correctly
+            # resynchronized after the decoder is closed.
+            fileobj.read(50)
+            fileobj.seek(0)
+            with plibflac.Decoder(fileobj) as decoder:
+                decoder.read(5000)
+            next_pos1 = fileobj.tell()
+            next_bytes1 = fileobj.read(100)
+
+            fileobj = fileobj.raw
+            fileobj.seek(0)
+            with plibflac.Decoder(fileobj) as decoder:
+                decoder.read(5000)
+            next_pos2 = fileobj.tell()
+            next_bytes2 = fileobj.read(100)
+
+        self.assertEqual(next_pos1, next_pos2)
+        self.assertEqual(next_bytes1, next_bytes2)
+
     def test_read_bytesio(self):
         """
         Test reading from a BytesIO object.