py3: Monkey-patch json.loads to accept bytes on py35

I'm tired of creating code churn where I just slap

    .decode("nearly arbitrary choice of encoding")

in a bunch of places.

Change-Id: I79b2bc59fed130ca537e96c1074212861d7db6b8

1 files changed, 35 insertions, 0 deletions

diff --git a/swift/__init__.py b/swift/__init__.py
index 9d0e8896f..f9f093132 100644
--- a/swift/__init__.py
+++ b/swift/__init__.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import os
+import sys
 import gettext
 
 import pkg_resources
@@ -39,3 +40,37 @@ _t = gettext.translation('swift', localedir=_localedir, fallback=True)
 
 def gettext_(msg):
     return _t.gettext(msg)
+
+
+if (3, 0) <= sys.version_info[:2] <= (3, 5):
+    # In the development of py3, json.loads() stopped accepting byte strings
+    # for a while. https://bugs.python.org/issue17909 got fixed for py36, but
+    # since it was termed an enhancement and not a regression, we don't expect
+    # any backports. At the same time, it'd be better if we could avoid
+    # leaving a whole bunch of json.loads(resp.body.decode(...)) scars in the
+    # code that'd probably persist even *after* we drop support for 3.5 and
+    # earlier. So, monkey patch stdlib.
+    import json
+    if not getattr(json.loads, 'patched_to_decode', False):
+        class JsonLoadsPatcher(object):
+            def __init__(self, orig):
+                self._orig = orig
+
+            def __call__(self, s, **kw):
+                if isinstance(s, bytes):
+                    # No fancy byte-order mark detection for us; just assume
+                    # UTF-8 and raise a UnicodeDecodeError if appropriate.
+                    s = s.decode('utf8')
+                return self._orig(s, **kw)
+
+            def __getattribute__(self, attr):
+                if attr == 'patched_to_decode':
+                    return True
+                if attr == '_orig':
+                    return super().__getattribute__(attr)
+                # Pass through all other attrs to the original; among other
+                # things, this preserves doc strings, etc.
+                return getattr(self._orig, attr)
+
+        json.loads = JsonLoadsPatcher(json.loads)
+        del JsonLoadsPatcher