File bpo27321-email-no-replace-header.patch of Package python3

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File bpo27321-email-no-replace-header.patch of Package python3

From 3c864b72138be6a559e36772246215aaef504a11 Mon Sep 17 00:00:00 2001
From: Mark Sapiro <mark@msapiro.net>
Date: Mon, 19 Oct 2020 16:11:37 -0700
Subject: [PATCH] fix email.generator.py to not replace a non-existent header

This PR replaces GH-1977. The reason for the replacement is
two-fold.

The fix itself is different is that if the CTE header doesn't
exist in the original message, it is inserted. This is important
because the new CTE could be quoted-printable whereas the
original is implicit 8bit.

Also the tests are different. The
test_nonascii_as_string_without_cte test in gh-1977 doesn't
actually test the issue in that it passes without the fix. The
test_nonascii_as_string_without_content_type_and_cte test is
improved here, and even though it doesn't fail without the fix,
it is included for completeness.

Fixed KeyError exception when flattening an email to a string
attempts to replace a non-existent Content-Transfer-Encoding
header.

Code is originally from gh#python/cpython@371146a3f8, it was
released upstream in 3.8.7

Co-authored-by: Mark Sapiro <mark@msapiro.net>
Date: Mon, 19 Oct 2020 16:11:37 -0700
Fixes: bsc#1208443
Patch: bpo27321-email-no-replace-header.patch
---
 Lib/email/generator.py                        |  6 +++-
 Lib/test/test_email/test_email.py             | 35 +++++++++++++++++++
 .../2020-01-19-18-40-26.bpo-27321.8e6SpM.rst  |  2 ++
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2020-01-19-18-40-26.bpo-27321.8e6SpM.rst

diff --git a/Lib/email/generator.py b/Lib/email/generator.py
index ae670c2353c..c9b121624e0 100644
--- a/Lib/email/generator.py
+++ b/Lib/email/generator.py
@@ -186,7 +186,11 @@ class Generator:
         # If we munged the cte, copy the message again and re-fix the CTE.
         if munge_cte:
             msg = deepcopy(msg)
-            msg.replace_header('content-transfer-encoding', munge_cte[0])
+            # Preserve the header order if the CTE header already exists.
+            if msg.get('content-transfer-encoding') is None:
+                msg['Content-Transfer-Encoding'] = munge_cte[0]
+            else:
+                msg.replace_header('content-transfer-encoding', munge_cte[0])
             msg.replace_header('content-type', munge_cte[1])
         # Write the headers.  First we see if the message object wants to
         # handle that itself.  If not, we'll do it generically.
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index e4e40b612fe..fc0b8a0d9ba 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -314,6 +314,41 @@ class TestMessageAPI(TestEmailBase):
         g.flatten(msg)
         self.assertEqual(fullrepr, s.getvalue())
 
+    def test_nonascii_as_string_without_cte(self):
+        m = textwrap.dedent("""\
+            MIME-Version: 1.0
+            Content-type: text/plain; charset="iso-8859-1"
+
+            Test if non-ascii messages with no Content-Transfer-Encoding set
+            can be as_string'd:
+            Föö bär
+            """)
+        source = m.encode('iso-8859-1')
+        expected = textwrap.dedent("""\
+            MIME-Version: 1.0
+            Content-type: text/plain; charset="iso-8859-1"
+            Content-Transfer-Encoding: quoted-printable
+
+            Test if non-ascii messages with no Content-Transfer-Encoding set
+            can be as_string'd:
+            F=F6=F6 b=E4r
+            """)
+        msg = email.message_from_bytes(source)
+        self.assertEqual(msg.as_string(), expected)
+
+    def test_nonascii_as_string_without_content_type_and_cte(self):
+        m = textwrap.dedent("""\
+            MIME-Version: 1.0
+
+            Test if non-ascii messages with no Content-Type nor
+            Content-Transfer-Encoding set can be as_string'd:
+            Föö bär
+            """)
+        source = m.encode('iso-8859-1')
+        expected = source.decode('ascii', 'replace')
+        msg = email.message_from_bytes(source)
+        self.assertEqual(msg.as_string(), expected)
+
     def test_as_bytes(self):
         msg = self._msgobj('msg_01.txt')
         with openfile('msg_01.txt') as fp:
diff --git a/Misc/NEWS.d/next/Library/2020-01-19-18-40-26.bpo-27321.8e6SpM.rst b/Misc/NEWS.d/next/Library/2020-01-19-18-40-26.bpo-27321.8e6SpM.rst
new file mode 100644
index 00000000000..28acf7f6ef9
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-01-19-18-40-26.bpo-27321.8e6SpM.rst
@@ -0,0 +1,2 @@
+Fixed KeyError exception when flattening an email to a string attempts to
+replace a non-existent Content-Transfer-Encoding header.
-- 
2.45.0

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File bpo27321-email-no-replace-header.patch of Package python3

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