Fix bug 983206 : _try_convert parsing string

* _try_convert in ec2utils.py didn't handle strings starting with "0x"
* Added tests to cover bug
* Add better float support
* remove unused complex number support

Change-Id: I382d36f4a8671bcceccfa1ebdbae89a9d2aca207

1 files changed, 11 insertions, 24 deletions

diff --git a/nova/api/ec2/ec2utils.py b/nova/api/ec2/ec2utils.py
index 045ee12d3..9006da93e 100644
--- a/nova/api/ec2/ec2utils.py
+++ b/nova/api/ec2/ec2utils.py
@@ -220,6 +220,10 @@ def _try_convert(value):
     *             try conversion to int, float, complex, fallback value
 
     """
+    def _negative_zero(value):
+        epsilon = 1e-7
+        return 0 if abs(value) < epsilon else value
+
     if len(value) == 0:
         return ''
     if value == 'None':
@@ -229,31 +233,14 @@ def _try_convert(value):
         return True
     if lowered_value == 'false':
         return False
-    valueneg = value[1:] if value[0] == '-' else value
-    if valueneg == '0':
-        return 0
-    if valueneg == '':
-        return value
-    if valueneg[0] == '0':
-        if valueneg[1] in 'xX':
-            return int(value, 16)
-        elif valueneg[1] in 'bB':
-            return int(value, 2)
-        else:
-            try:
-                return int(value, 8)
-            except ValueError:
-                pass
-    try:
-        return int(value)
-    except ValueError:
-        pass
-    try:
-        return float(value)
-    except ValueError:
-        pass
+    for prefix, base in [('0x', 16), ('0b', 2), ('0', 8), ('', 10)]:
+        try:
+            if lowered_value.startswith((prefix, "-" + prefix)):
+                return int(lowered_value, base)
+        except ValueError:
+            pass
     try:
-        return complex(value)
+        return _negative_zero(float(value))
     except ValueError:
         return value