D1136: templatefilters: defend against evil unicode strs in json filter

[durin42 (Augie Fackler)]

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

REVISION SUMMARY
  We only want to do I/O in terms of bytes, so lets explode early
  instead of recursing forever.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1136

AFFECTED FILES
  mercurial/templatefilters.py

CHANGE DETAILS

diff --git a/mercurial/templatefilters.py b/mercurial/templatefilters.py
--- a/mercurial/templatefilters.py
+++ b/mercurial/templatefilters.py
@@ -233,6 +233,13 @@
         return pycompat.bytestr(obj)
     elif isinstance(obj, bytes):
         return '"%s"' % encoding.jsonescape(obj, paranoid=paranoid)
+    elif isinstance(obj, str):
+        # This branch is unreachable on Python 2, because bytes == str
+        # and we'll return in the next-earlier block in the elif
+        # ladder. On Python 3, this helps us catch bugs before they
+        # hurt someone.
+        raise TypeError(
+            r'Mercurial only does output with bytes on Python 3: %r' % obj)
     elif util.safehasattr(obj, 'keys'):
         out = ['"%s": %s' % (encoding.jsonescape(k, paranoid=paranoid),
                              json(v, paranoid))



To: durin42, #hg-reviewers
Cc: mercurial-devel