From 23f5f657392e50036f6de4129f58061f682bd968 Mon Sep 17 00:00:00 2001
From: Sebastien Binet <binet@cern.ch>
Date: Mon, 7 Aug 2017 16:17:24 +0200
Subject: [PATCH] bind/cffi: handle strings from error.Error

This CL introduces a convenience function cffi_cgopy_cnv_c2py_errstring
to properly handle (and decode) strings coming from error.Error calls.
---
 _examples/pyerrors/test.py |  2 +-
 bind/gencffi.go            |  9 +++++++++
 bind/gencffi_func.go       | 16 ++++------------
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/_examples/pyerrors/test.py b/_examples/pyerrors/test.py
index 5211b01..587145b 100644
--- a/_examples/pyerrors/test.py
+++ b/_examples/pyerrors/test.py
@@ -12,7 +12,7 @@ def div(a, b):
         r = pyerrors.Div(a, b)
         print("pyerrors.Div(%d, %d) = %d"% (a, b, r))
     except Exception as e:
-        print(str(e))
+        print(e)
 
 div(5,0)
 div(5,2)
diff --git a/bind/gencffi.go b/bind/gencffi.go
index d280f4b..c0a1e84 100644
--- a/bind/gencffi.go
+++ b/bind/gencffi.go
@@ -129,6 +129,15 @@ class _cffi_helper(object):
             pystr = pystr.decode('ascii')
         return pystr
 
+    @staticmethod
+    def cffi_cgopy_cnv_c2py_errstring(c):
+        s = _cffi_helper.lib._cgopy_ErrorString(c)
+        pystr = ffi.string(s)
+        _cffi_helper.lib._cgopy_FreeCString(s)
+        if _PY3:
+            pystr = pystr.decode('ascii')
+        return pystr
+
     @staticmethod
     def cffi_cgopy_cnv_c2py_int(c):
         return int(c)
diff --git a/bind/gencffi_func.go b/bind/gencffi_func.go
index 080b56e..c5eae16 100644
--- a/bind/gencffi_func.go
+++ b/bind/gencffi_func.go
@@ -64,9 +64,7 @@ func (g *cffiGen) genMethodBody(s Struct, m Func) {
 		case 1:
 			g.wrapper.Printf("if not _cffi_helper.lib._cgopy_ErrorIsNil(cret):\n")
 			g.wrapper.Indent()
-			g.wrapper.Printf("c_err_str = _cffi_helper.lib._cgopy_ErrorString(cret)\n")
-			g.wrapper.Printf("py_err_str = ffi.string(c_err_str)\n")
-			g.wrapper.Printf("_cffi_helper.lib._cgopy_FreeCString(c_err_str)\n")
+			g.wrapper.Printf("py_err_str = _cffi_helper.cffi_cgopy_cnv_c2py_errstring(cret)\n")
 			g.wrapper.Printf("raise RuntimeError(py_err_str)\n")
 			g.wrapper.Outdent()
 			g.wrapper.Printf("return\n")
@@ -74,9 +72,7 @@ func (g *cffiGen) genMethodBody(s Struct, m Func) {
 		case 2:
 			g.wrapper.Printf("if not _cffi_helper.lib._cgopy_ErrorIsNil(cret.r1):\n")
 			g.wrapper.Indent()
-			g.wrapper.Printf("c_err_str = _cffi_helper.lib._cgopy_ErrorString(cret.r1)\n")
-			g.wrapper.Printf("py_err_str = ffi.string(c_err_str)\n")
-			g.wrapper.Printf("_cffi_helper.lib._cgopy_FreeCString(c_err_str)\n")
+			g.wrapper.Printf("py_err_str = _cffi_helper.cffi_cgopy_cnv_c2py_errstring(cret.r1)\n")
 			g.wrapper.Printf("raise RuntimeError(py_err_str)\n")
 			g.wrapper.Outdent()
 			if res[0].sym.hasConverter() {
@@ -212,9 +208,7 @@ func (g *cffiGen) genFuncBody(f Func) {
 		case 1:
 			g.wrapper.Printf("if not _cffi_helper.lib._cgopy_ErrorIsNil(cret):\n")
 			g.wrapper.Indent()
-			g.wrapper.Printf("c_err_str = _cffi_helper.lib._cgopy_ErrorString(cret)\n")
-			g.wrapper.Printf("py_err_str = ffi.string(c_err_str)\n")
-			g.wrapper.Printf("_cffi_helper.lib._cgopy_FreeCString(c_err_str)\n")
+			g.wrapper.Printf("py_err_str = _cffi_helper.cffi_cgopy_cnv_c2py_errstring(cret)\n")
 			g.wrapper.Printf("raise RuntimeError(py_err_str)\n")
 			g.wrapper.Outdent()
 			g.wrapper.Printf("return\n")
@@ -222,9 +216,7 @@ func (g *cffiGen) genFuncBody(f Func) {
 		case 2:
 			g.wrapper.Printf("if not _cffi_helper.lib._cgopy_ErrorIsNil(cret.r1):\n")
 			g.wrapper.Indent()
-			g.wrapper.Printf("c_err_str = _cffi_helper.lib._cgopy_ErrorString(cret.r1)\n")
-			g.wrapper.Printf("py_err_str = ffi.string(c_err_str)\n")
-			g.wrapper.Printf("_cffi_helper.lib._cgopy_FreeCString(c_err_str)\n")
+			g.wrapper.Printf("py_err_str = _cffi_helper.cffi_cgopy_cnv_c2py_errstring(cret.r1)\n")
 			g.wrapper.Printf("raise RuntimeError(py_err_str)\n")
 			g.wrapper.Outdent()
 			if res[0].sym.hasConverter() {