D3953: mail: fix _encode to be more correct on Python 3

[durin42 (Augie Fackler)]

durin42 created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  This code appears to be on the wrong side of the law in Python 2, at
  least some of the time. In Python 3, it's definitely wrong in places,
  but fortunately that's easy to fix.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D3953

AFFECTED FILES
  mercurial/mail.py

CHANGE DETAILS

diff --git a/mercurial/mail.py b/mercurial/mail.py
--- a/mercurial/mail.py
+++ b/mercurial/mail.py
@@ -252,18 +252,35 @@
     order. Tries both encoding and fallbackencoding for input. Only as
     last resort send as is in fake ascii.
     Caveat: Do not use for mail parts containing patches!'''
+    sendcharsets = charsets or _charsets(ui)
+    if not isinstance(s, bytes):
+        # We have unicode data, which we need to try and encode to
+        # some reasonable-ish encoding. Try the encodings the user
+        # wants, and fall back to garbage-in-ascii.
+        for ocs in sendcharsets:
+            try:
+                return s.encode(pycompat.sysstr(ocs)), ocs
+            except UnicodeEncodeError:
+                pass
+            except LookupError:
+                ui.warn(_('ignoring invalid sendcharset: %s\n') % ocs)
+        else:
+            # Everything failed, ascii-armor what we've got and send it.
+            return s.encode('ascii', 'backslashreplace')
+    # We have a bytes of unknown encoding. We'll try and guess a valid
+    # encoding, falling back to pretending we had ascii even though we
+    # know that's wrong.
     try:
         s.decode('ascii')
     except UnicodeDecodeError:
-        sendcharsets = charsets or _charsets(ui)
         for ics in (encoding.encoding, encoding.fallbackencoding):
             try:
                 u = s.decode(ics)
             except UnicodeDecodeError:
                 continue
             for ocs in sendcharsets:
                 try:
-                    return u.encode(ocs), ocs
+                    return u.encode(pycompat.sysstr(ocs)), ocs
                 except UnicodeEncodeError:
                     pass
                 except LookupError:



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