gh-91217: deprecate uu (GH-92009)

Automerge-Triggered-By: GH:brettcannon

Lib/email/message.py

@@ -6,8 +6,8 @@
 
 __all__ = ['Message', 'EmailMessage']
 
+import binascii
 import re
-import uu
 import quopri
 from io import BytesIO, StringIO
 
@@ -35,7 +35,7 @@ def _splitparam(param):
     if not sep:
         return a.strip(), None
     return a.strip(), b.strip()
-
+
 def _formatparam(param, value=None, quote=True):
     """Convenience function to format and return a key=value pair.
 
@@ -101,7 +101,37 @@ def _unquotevalue(value):
         return utils.unquote(value)
 
 
-
+def _decode_uu(encoded):
+    """Decode uuencoded data."""
+    decoded_lines = []
+    encoded_lines_iter = iter(encoded.splitlines())
+    for line in encoded_lines_iter:
+        if line.startswith(b"begin "):
+            mode, _, path = line.removeprefix(b"begin ").partition(b" ")
+            try:
+                int(mode, base=8)
+            except ValueError:
+                continue
+            else:
+                break
+    else:
+        raise ValueError("`begin` line not found")
+    for line in encoded_lines_iter:
+        if not line:
+            raise ValueError("Truncated input")
+        elif line.strip(b' \t\r\n\f') == b'end':
+            break
+        try:
+            decoded_line = binascii.a2b_uu(line)
+        except binascii.Error:
+            # Workaround for broken uuencoders by /Fredrik Lundh
+            nbytes = (((line[0]-32) & 63) * 4 + 5) // 3
+            decoded_line = binascii.a2b_uu(line[:nbytes])
+        decoded_lines.append(decoded_line)
+
+    return b''.join(decoded_lines)
+
+
 class Message:
     """Basic message object.
 
@@ -288,13 +318,10 @@ class Message:
                 self.policy.handle_defect(self, defect)
             return value
         elif cte in ('x-uuencode', 'uuencode', 'uue', 'x-uue'):
-            in_file = BytesIO(bpayload)
-            out_file = BytesIO()
             try:
-                uu.decode(in_file, out_file, quiet=True)
-                return out_file.getvalue()
-            except uu.Error:
-                # Some decoding problem
+                return _decode_uu(bpayload)
+            except ValueError:
+                # Some decoding problem.
                 return bpayload
         if isinstance(payload, str):
             return bpayload