fix json dbus.Double encoding

- bad formatting showed up in rest server queries
- json used the highest level repr method, which will call the dbus type
tp_repr method. Instead we should use the float specific repr method.

resolves openbmc/openbmc#411

Change-Id: I04eea6d825fe3833accf1625e138abedb0aa7c95
Signed-off-by: Edward A. James <eajames@us.ibm.com>

2 files changed, 67 insertions, 0 deletions

diff --git a/meta-phosphor/common/recipes-devtools/python/python/issue_27934_use-float-repr.patch b/meta-phosphor/common/recipes-devtools/python/python/issue_27934_use-float-repr.patch
new file mode 100644
index 000000000..0f8bb3351
--- /dev/null
+++ b/meta-phosphor/common/recipes-devtools/python/python/issue_27934_use-float-repr.patch
@@ -0,0 +1,66 @@
+# HG changeset patch
+# User Mark Dickinson <dickinsm@gmail.com>
+# Date 1472921100 -3600
+# Node ID 86d66a627b774d741d9a8834f16706ba3de61953
+# Parent  e065aec0e6fa04000e3e57da45139e11df0c675f
+Issue #27934: Use float.__repr__ instead of plain repr when JSON-encoding an instance of a float subclass. Thanks Eddie James.
+
+diff --git a/Lib/json/encoder.py b/Lib/json/encoder.py
+--- a/Lib/json/encoder.py
++++ b/Lib/json/encoder.py
+@@ -28,7 +28,7 @@ for i in range(0x20):
+     #ESCAPE_DCT.setdefault(chr(i), '\\u%04x' % (i,))
+ 
+ INFINITY = float('inf')
+-FLOAT_REPR = repr
++FLOAT_REPR = float.__repr__
+ 
+ def encode_basestring(s):
+     """Return a JSON representation of a Python string
+diff --git a/Lib/json/tests/test_float.py b/Lib/json/tests/test_float.py
+--- a/Lib/json/tests/test_float.py
++++ b/Lib/json/tests/test_float.py
+@@ -32,6 +32,17 @@ class TestFloat(object):
+                 self.assertNotEqual(res[0], res[0])
+             self.assertRaises(ValueError, self.dumps, [val], allow_nan=False)
+ 
++    def test_float_subclasses_use_float_repr(self):
++        # Issue 27934.
++        class PeculiarFloat(float):
++            def __repr__(self):
++                return "I'm not valid JSON"
++            def __str__(self):
++                return "Neither am I"
++
++        val = PeculiarFloat(3.2)
++        self.assertEqual(self.loads(self.dumps(val)), val)
++
+ 
+ class TestPyFloat(TestFloat, PyTest): pass
+ class TestCFloat(TestFloat, CTest): pass
+diff --git a/Misc/ACKS b/Misc/ACKS
+--- a/Misc/ACKS
++++ b/Misc/ACKS
+@@ -636,6 +636,7 @@ Manuel Jacob
+ David Jacobs
+ Kevin Jacobs
+ Kjetil Jacobsen
++Eddie James
+ Bertrand Janin
+ Geert Jansen
+ Jack Jansen
+diff --git a/Modules/_json.c b/Modules/_json.c
+--- a/Modules/_json.c
++++ b/Modules/_json.c
+@@ -1960,8 +1960,8 @@ encoder_encode_float(PyEncoderObject *s,
+             return PyString_FromString("NaN");
+         }
+     }
+-    /* Use a better float format here? */
+-    return PyObject_Repr(obj);
++    /* Make sure to use the base float class repr method */
++    return PyFloat_Type.tp_repr(obj);
+ }
+ 
+ static PyObject *
+
diff --git a/meta-phosphor/common/recipes-devtools/python/python_2.7.11.bbappend b/meta-phosphor/common/recipes-devtools/python/python_2.7.11.bbappend
index 569e75397..f5c58e3d4 100644
--- a/meta-phosphor/common/recipes-devtools/python/python_2.7.11.bbappend
+++ b/meta-phosphor/common/recipes-devtools/python/python_2.7.11.bbappend
@@ -1,5 +1,6 @@
 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
 SRC_URI += "file://__init__.email_min.py"
+SRC_URI += "file://issue_27934_use-float-repr.patch"
 
 do_install_append_class-target() {
 	dir=${libdir}/python${PYTHON_MAJMIN}/email