preserve original traceback on py3

2 files changed, 17 insertions, 9 deletions

diff --git a/pysnmp/proto/mpmod/rfc3412.py b/pysnmp/proto/mpmod/rfc3412.py
index cafa002..801fcbe 100644
--- a/pysnmp/proto/mpmod/rfc3412.py
+++ b/pysnmp/proto/mpmod/rfc3412.py
@@ -524,7 +524,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
                 )
             debug.logger & debug.flagMP and debug.logger('prepareDataElements: SM succeeded')
         except error.StatusInformation:
-            statusInformation = sys.exc_info()[1]
+            statusInformation, origTraceback = sys.exc_info()[1:3]
             debug.logger & debug.flagMP and debug.logger('prepareDataElements: SM failed, statusInformation %s' % statusInformation)
             if 'errorIndication' in statusInformation:
                 # 7.2.6a
@@ -585,7 +585,15 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
                     
                     debug.logger & debug.flagMP and debug.logger('prepareDataElements: error reported')
             # 7.2.6b
-            raise statusInformation
+            if sys.version_info[0] <= 2:
+                raise statusInformation
+            else:
+                try:
+                    raise statusInformation.with_traceback(origTraceback)
+                finally:
+                    # Break cycle between locals and traceback object	
+                    # (seems to be irrelevant on Py3 but just in case)
+                    del origTraceback
         else:
             # Sniff for engineIDs
             k = (transportDomain, transportAddress)
diff --git a/pysnmp/smi/instrum.py b/pysnmp/smi/instrum.py
index c9cba39..f5f085a 100644
--- a/pysnmp/smi/instrum.py
+++ b/pysnmp/smi/instrum.py
@@ -179,7 +179,7 @@ class MibInstrumController:
         mibTree, = self.mibBuilder.importSymbols('SNMPv2-SMI', 'iso')
         outputNameVals = []
         state, status = 'start', 'ok'
-        myErr = None
+        origExc = None
         while 1:
             k = (state, status)
             if k in fsmTable:
@@ -210,8 +210,8 @@ class MibInstrumController:
                     rval = f(tuple(name), val, idx, acInfo)
                 except error.SmiError:
                     debug.logger & debug.flagIns and debug.logger('flipFlopFsm: fun %s failed %s for %s=%r' % (f, sys.exc_info()[1], name, val))
-                    if myErr is None:  # Take the first exception
-                        myErr = sys.exc_info()
+                    if origExc is None:  # Take the first exception
+                        origExc, origTraceback = sys.exc_info()[1:3]
                     status = 'err'
                     break
                 else:
@@ -219,16 +219,16 @@ class MibInstrumController:
                     if rval is not None:
                         outputNameVals.append((rval[0], rval[1]))
                 idx = idx + 1
-        if myErr:
+        if origExc:
             if sys.version_info[0] <= 2:
-                raise myErr[1]
+                raise origExc
             else:
                 try:
-                    raise myErr[1].with_traceback(myErr[2])
+                    raise origExc.with_traceback(origTraceback)
                 finally:
                     # Break cycle between locals and traceback object
                     # (seems to be irrelevant on Py3 but just in case)
-                    del myErr
+                    del origTraceback
         return outputNameVals
     
     def readVars(self, vars, acInfo=(None, None)):