Refactoring

Added comments. Removed fifth line from test because it was unnecessary
since the final line could be used instead.

2 files changed, 10 insertions, 6 deletions

diff --git a/paramiko/file.py b/paramiko/file.py
index f549cb99..1c99abeb 100644
--- a/paramiko/file.py
+++ b/paramiko/file.py
@@ -204,7 +204,7 @@ class BufferedFile (object):
         if not (self._flags & self.FLAG_READ):
             raise IOError('File not open for reading')
         line = self._rbuffer
-        truncated = False;
+        truncated = False
         while True:
             if self._at_trailing_cr and (self._flags & self.FLAG_UNIVERSAL_NEWLINE) and (len(line) > 0):
                 # edge case: the newline may be '\r\n' and we may have read
@@ -246,12 +246,15 @@ class BufferedFile (object):
             if (rpos >= 0) and (rpos < pos or pos < 0):
                 pos = rpos
         if pos == -1:
+            # we couldn't find a newline in the truncated string, return it
             self._pos += len(line)
             return line if self._flags & self.FLAG_BINARY else u(line)
         xpos = pos + 1
         if (line[pos] == cr_byte_value) and (xpos < len(line)) and (line[xpos] == linefeed_byte_value):
             xpos += 1
-        
+        # if the string was truncated, _rbuffer needs to have the string after 
+        # the newline character plus the truncated part of the line we stored
+        # earlier in _rbuffer
         self._rbuffer = line[xpos:] + self._rbuffer if truncated else line[xpos:]
         lf = line[pos:xpos]
         line = line[:pos] + linefeed_byte
diff --git a/tests/test_file.py b/tests/test_file.py
index 044dc591..a6ff69e9 100755
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -70,16 +70,17 @@ class BufferedFileTest (unittest.TestCase):
 
     def test_2_readline(self):
         f = LoopbackFile('r+U')
-        f.write(b'First line.\nSecond line.\r\nThird line.\nFourth line.\nFifth line.\nFinal line non-terminated.')
+        f.write(b'First line.\nSecond line.\r\nThird line.\n' + 
+                b'Fourth line.\nFinal line non-terminated.')
+        
         self.assertEqual(f.readline(), 'First line.\n')
         # universal newline mode should convert this linefeed:
         self.assertEqual(f.readline(), 'Second line.\n')
         # truncated line:
         self.assertEqual(f.readline(7), 'Third l')
         self.assertEqual(f.readline(), 'ine.\n')
-        # readline should not read past the fourth line
-        self.assertEqual(f.readline(25), 'Fourth line.\n')
-        self.assertEqual(f.readline(), 'Fifth line.\n')
+        # newline should be detected and only the fourth line returned
+        self.assertEqual(f.readline(39), 'Fourth line.\n')
         self.assertEqual(f.readline(), 'Final line non-terminated.')
         self.assertEqual(f.readline(), '')
         f.close()