gh-78981: Update contentmanager to handle 0/None max_line_length

Lib/email/contentmanager.py

@@ -133,6 +133,8 @@ def _finalize_set(msg, disposition, filename, cid, params):
 # drop both this and quoprimime.body_encode in favor of enhanced binascii
 # routines that accepted a max_line_length parameter.
 def _encode_base64(data, max_line_length):
+    if not max_line_length:
+        return binascii.b2a_base64(data).decode('ascii')
     encoded_lines = []
     unencoded_bytes_per_line = max_line_length // 4 * 3
     for i in range(0, len(data), unencoded_bytes_per_line):
@@ -148,7 +150,10 @@ def embedded_body(lines): return linesep.join(lines) + linesep
     def normal_body(lines): return b'\n'.join(lines) + b'\n'
     if cte is None:
         # Use heuristics to decide on the "best" encoding.
-        if max((len(x) for x in lines), default=0) <= policy.max_line_length:
+        if (
+            not policy.max_line_length or
+            max((len(x) for x in lines), default=0) <= policy.max_line_length
+        ):
             try:
                 return '7bit', normal_body(lines).decode('ascii')
             except UnicodeDecodeError:

Lib/email/quoprimime.py

@@ -40,6 +40,7 @@
     ]
 
 import re
+import sys
 
 from string import ascii_letters, digits, hexdigits
 
@@ -169,6 +170,9 @@ def body_encode(body, maxlinelen=76, eol=NL):
 
     """
 
+    if not maxlinelen:
+        maxlinelen = sys.maxsize
+
     if maxlinelen < 4:
         raise ValueError("maxlinelen must be at least 4")
     if not body:

Lib/test/test_email/test_contentmanager.py

@@ -481,6 +481,45 @@ def test_set_text_11_lines_long_line_maximal_non_ascii_heuristics(self):
         self.assertEqual(m.get_payload(decode=True).decode('utf-8'), content)
         self.assertEqual(m.get_content(), content)
 
+    def test_set_text_non_ascii_with_policy_max_line_length_none_or_0(self):
+        for max_line_length in (0, None):
+            with self.subTest(max_line_length=max_line_length):
+                policy = self.policy.clone(max_line_length=max_line_length)
+                m = self.message(policy=policy)
+                content = ("áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő"
+                        "áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő"
+                        "áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő.\n")
+                raw_data_manager.set_content(m, content)
+                self.assertEqual(bytes(m), (textwrap.dedent("""\
+                    Content-Type: text/plain; charset="utf-8"
+                    Content-Transfer-Encoding: 8bit
+                    """) + "\n" + \
+                    "áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő"
+                    "áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő"
+                    "áàäéèęöőáàäéèęöőáàäéèęöőáàäéèęöő.\n"
+                    ).encode('utf8'))
+                self.assertEqual(
+                    m.get_payload(decode=True).decode('utf-8'), content)
+                self.assertEqual(m.get_content(), content)
+
+    def test_set_bytes_with_policy_max_line_length_none_or_0(self):
+        for max_line_length in (0, None):
+            with self.subTest(max_line_length=max_line_length):
+                policy = self.policy.clone(max_line_length=max_line_length)
+                m = self.message(policy=policy)
+                content = b'b\xFFgus\tcon\nt\rent ' + b'z'*80
+                raw_data_manager.set_content(
+                    m, content, maintype='application', subtype='octet-stream')
+                self.assertEqual(bytes(m), textwrap.dedent("""\
+                    Content-Type: application/octet-stream
+                    Content-Transfer-Encoding: base64
+                    """).encode('ascii') + b"\n" +
+                    b"Yv9ndXMJY29uCnQNZW50IHp6enp6enp6enp6enp6enp6enp6enp6enp6"
+                    b"enp6enp6enp6enp6enp6enp6enp6enp6enp6enp6enp6enp6enp6enp6"
+                    b"enp6enp6enp6enp6\n")
+                self.assertEqual(m.get_payload(decode=True), content)
+                self.assertEqual(m.get_content(), content)
+
     def test_set_text_non_ascii_with_cte_7bit_raises(self):
         m = self._make_message()
         with self.assertRaises(UnicodeError):

Misc/NEWS.d/next/Library/2024-09-01-20-20-49.gh-issue-78981.nNRvSX.rst

@@ -0,0 +1,2 @@
+Fixed a bug where ``email.contentmanager.set_content`` raised error when
+``email.policy.Policy.max_line_length`` is 0 or ``None``. Patch by silane.