Merge branch '1.13' into 1.14

3 files changed, 21 insertions, 5 deletions

diff --git a/paramiko/file.py b/paramiko/file.py
index 0a7fbcba..1c99abeb 100644
--- a/paramiko/file.py
+++ b/paramiko/file.py
@@ -204,6 +204,7 @@ class BufferedFile (object):
         if not (self._flags & self.FLAG_READ):
             raise IOError('File not open for reading')
         line = self._rbuffer
+        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
@@ -218,11 +219,11 @@ class BufferedFile (object):
             # enough.
             if (size is not None) and (size >= 0):
                 if len(line) >= size:
-                    # truncate line and return
+                    # truncate line
                     self._rbuffer = line[size:]
                     line = line[:size]
-                    self._pos += len(line)
-                    return line if self._flags & self.FLAG_BINARY else u(line)
+                    truncated = True
+                    break
                 n = size - len(line)
             else:
                 n = self._bufsize
@@ -244,10 +245,17 @@ class BufferedFile (object):
             rpos = line.find(cr_byte)
             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
-        self._rbuffer = line[xpos:]
+        # 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
         if (len(self._rbuffer) == 0) and (lf == cr_byte):
diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index e61614b2..02b42255 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* :bug:`428` Fix an issue in `~paramiko.file.BufferedFile` (primarily used in
+  the SFTP modules) concerning incorrect behavior by
+  `~paramiko.file.BufferedFile.readlines` on files whose size exceeds the
+  buffer size. Thanks to ``@achapp`` for catch & patch.
 * :support:`422` Clean up some unused imports. Courtesy of Olle Lundberg.
 * :bug:`266` Change numbering of `~paramiko.transport.Transport` channels to
   start at 0 instead of 1 for better compatibility with OpenSSH & certain
diff --git a/tests/test_file.py b/tests/test_file.py
index 22a34aca..a6ff69e9 100755
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -70,13 +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.\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')
+        # 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()