From c1a09a4237f8af777560789adfef18b2e72672f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Natal=20Ng=C3=A9tal?= <hobbestigrou@erakis.eu>
Date: Tue, 4 Dec 2018 18:03:19 +0100
Subject: [PATCH] bpo-5430: Preservation LF, CR in IMAP4 append method.

Preserve LF, CR in the append method.

Co-authored-by: Ron DuPlain <ron.duplain@gmail.com>
---
 Lib/imaplib.py                                |  3 +--
 Lib/test/test_imaplib.py                      | 19 +++++++++++++++++++
 .../2018-12-04-18-10-11.bpo-5430.5adoEJ.rst   |  1 +
 3 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2018-12-04-18-10-11.bpo-5430.5adoEJ.rst

diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index dd237f7704aca0b..c5967c09a28ffd0 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -111,7 +111,6 @@
         br'"')
 # Literal is no longer used; kept for backward compatibility.
 Literal = re.compile(br'.*{(?P<size>\d+)}$', re.ASCII)
-MapCRLF = re.compile(br'\r\n|\r|\n')
 # We no longer exclude the ']' character from the data portion of the response
 # code, even though it violates the RFC.  Popular IMAP servers such as Gmail
 # allow flags with ']', and there are programs (including imaplib!) that can
@@ -396,7 +395,7 @@ def append(self, mailbox, flags, date_time, message):
             date_time = Time2Internaldate(date_time)
         else:
             date_time = None
-        literal = MapCRLF.sub(CRLF, message)
+        literal = message
         if self.utf8_enabled:
             literal = b'UTF8 (' + literal + b')'
         self.literal = literal
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index a0b598d0c784092..d66904dc1dd2d29 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -22,9 +22,28 @@
 CERTFILE = os.path.join(os.path.dirname(__file__) or os.curdir, "keycert3.pem")
 CAFILE = os.path.join(os.path.dirname(__file__) or os.curdir, "pycacert.pem")
 
+class DummyIMAP(imaplib.IMAP4):
+
+    def __init__(self):
+        """Skip connections, for testing."""
+        self.utf8_enabled = False
+
+    def _simple_command(self, name, *args):
+        """Return self.literal, for testing methods affecting literal."""
+        return self.literal
+
 
 class TestImaplib(unittest.TestCase):
 
+    # CR, LF in literal should not be replaced by CRLF, issue 5430
+    def test_cr_lf_literal_preservation(self):
+        dummy_imap = DummyIMAP()
+        msg_string = 'one\rtwo\nthree\r\n'
+        result = dummy_imap.append(
+            None, None, None, msg_string.encode('utf-8'))
+
+        self.assertEqual(str.encode(msg_string), result)
+
     def test_Internaldate2tuple(self):
         t0 = calendar.timegm((2000, 1, 1, 0, 0, 0, -1, -1, -1))
         tt = imaplib.Internaldate2tuple(
diff --git a/Misc/NEWS.d/next/Library/2018-12-04-18-10-11.bpo-5430.5adoEJ.rst b/Misc/NEWS.d/next/Library/2018-12-04-18-10-11.bpo-5430.5adoEJ.rst
new file mode 100644
index 000000000000000..bedfd80bfd3db72
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-12-04-18-10-11.bpo-5430.5adoEJ.rst
@@ -0,0 +1 @@
+Preserve LF, CR in the ``imaplib.IMAP4.append`` method.