* default /usr/share/mibs MIB source added

* compiler.addMibCompiler() now supports ifAvailable and ifNotAdded flags
* rfc1902.ObjectIdentity() now always tries to instantiate and attach
  MIB compiler to snmpEngine (if not done yet), also .addMibCompiler()
  renamed to .addAsn1MibSource() to signify the fact that MIB compiler
  is attached behind the scene

5 files changed, 39 insertions, 25 deletions

diff --git a/examples/smi/mib-lookup.py b/examples/smi/mib-lookup.py
index a208897..69bb7dc 100644
--- a/examples/smi/mib-lookup.py
+++ b/examples/smi/mib-lookup.py
@@ -14,7 +14,7 @@ mibVar = rfc1902.ObjectIdentity('IF-MIB', 'ifInOctets', 1)
 # create pysnmp MIBs on demand from ASN.1 sources downloaded from
 # a web site.
 try:
-    mibVar.addMibCompiler('http://mibs.snmplabs.com/asn1/@mib@')
+    mibVar.addAsn1MibSource('http://mibs.snmplabs.com/asn1/@mib@')
 except error.SmiError:
     print('WARNING: not using MIB compiler (PySMI not installed)')
 
diff --git a/examples/v3arch/manager/cmdgen/getnext-v2c-with-mib-compilation-and-lookup.py b/examples/v3arch/manager/cmdgen/getnext-v2c-with-mib-compilation-and-lookup.py
index a8c5b35..eab7906 100644
--- a/examples/v3arch/manager/cmdgen/getnext-v2c-with-mib-compilation-and-lookup.py
+++ b/examples/v3arch/manager/cmdgen/getnext-v2c-with-mib-compilation-and-lookup.py
@@ -21,7 +21,10 @@ from pysnmp.smi import compiler, view, rfc1902
 snmpEngine = engine.SnmpEngine()
 
 # Attach MIB compiler to SNMP Engine (MIB Builder)
+# This call will fail if PySMI is not present on the system
 compiler.addMibCompiler(snmpEngine.getMibBuilder())
+# ... alternatively, this call will not complain on missing PySMI
+#compiler.addMibCompiler(snmpEngine.getMibBuilder(), ifAvailable=True)
 
 # Used for MIB objects resolution
 mibViewController = view.MibViewController(snmpEngine.getMibBuilder())
diff --git a/examples/v3arch/oneliner/manager/cmdgen/get-v2c-with-mib-compilation-and-lookup.py b/examples/v3arch/oneliner/manager/cmdgen/get-v2c-with-mib-compilation-and-lookup.py
index 719460a..9c2db80 100644
--- a/examples/v3arch/oneliner/manager/cmdgen/get-v2c-with-mib-compilation-and-lookup.py
+++ b/examples/v3arch/oneliner/manager/cmdgen/get-v2c-with-mib-compilation-and-lookup.py
@@ -7,6 +7,7 @@
 # * over IPv4/UDP
 # * to an Agent at demo.snmplabs.com:161
 # * for IF-MIB::ifInOctets.1 MIB object
+# * Pass attached MIB compiler non-default ASN.1 MIB source
 #
 from pysnmp.entity.rfc3413.oneliner import cmdgen
 
@@ -15,7 +16,7 @@ cmdGen = cmdgen.CommandGenerator()
 errorIndication, errorStatus, errorIndex, varBinds = cmdGen.getCmd(
     cmdgen.CommunityData('public'),
     cmdgen.UdpTransportTarget(('demo.snmplabs.com', 161)),
-    cmdgen.ObjectIdentity('IF-MIB', 'ifInOctets', 1).addMibCompiler('file:///usr/share/snmp', 'http://mibs.snmplabs.com/asn1/@mib@'),
+    cmdgen.ObjectIdentity('IF-MIB', 'ifInOctets', 1).addAsn1MibSource('file:///usr/share/snmp', 'http://mibs.snmplabs.com/asn1/@mib@'),
     lookupNames=True, lookupValues=True
 )
 
diff --git a/pysnmp/smi/compiler.py b/pysnmp/smi/compiler.py
index 4efb224..0aa07d0 100644
--- a/pysnmp/smi/compiler.py
+++ b/pysnmp/smi/compiler.py
@@ -5,11 +5,12 @@
 import os
 import sys
 
-defaultSources = [ 'file:///usr/share/snmp/mibs' ]
+defaultSources = [ 'file:///usr/share/snmp/mibs',
+                   'file:///usr/share/mibs' ]
 
 if sys.platform[:3] == 'win':
     defaultDest = os.path.join(os.path.expanduser("~"),
-                                   'PySNMP Configuration', 'mibs')
+                               'PySNMP Configuration', 'mibs')
 else:
     defaultDest = os.path.join(os.path.expanduser("~"), '.pysnmp', 'mibs')
 
@@ -29,26 +30,23 @@ try:
 except ImportError:
     from pysnmp.smi import error
 
-    def addMibCompiler(mibBuilder,
-                       sources=[],
-                       destination='',
-                       borrowers=[]):
-        raise error.SmiError('MIB compiler not available (pysmi not installed)')
+    def addMibCompiler(mibBuilder, **kwargs):
+        if not kwargs.get('ifAvailable'):
+            raise error.SmiError('MIB compiler not available (pysmi not installed)')
 
 else:
 
-    def addMibCompiler(mibBuilder,
-                       sources=defaultSources,
-                       destination=defaultDest,
-                       borrowers=defaultBorrowers):
+    def addMibCompiler(mibBuilder, **kwargs):
+        if kwargs.get('ifNotAdded') and mibBuilder.getMibCompiler():
+            return
 
         compiler = MibCompiler(
             parserFactory(**smiV1Relaxed)(),
             PySnmpCodeGen(),
-            PyFileWriter(destination)
+            PyFileWriter(kwargs.get('destination') or defaultDest)
         )
 
-        compiler.addSources(*getReadersFromUrls(*sources))
+        compiler.addSources(*getReadersFromUrls(*kwargs.get('sources') or defaultSources))
 
         compiler.addSearchers(
             StubSearcher(*baseMibs) # XXX
@@ -56,9 +54,11 @@ else:
         compiler.addSearchers(
             *[ PyPackageSearcher(x.fullPath()) for x in mibBuilder.getMibSources() ]
         )
-
         compiler.addBorrowers(
-            *[ PyFileBorrower(x, genTexts=mibBuilder.loadTexts) for x in getReadersFromUrls(*borrowers, **dict(originalMatching=False, lowcaseMatching=False)) ]
+            *[ PyFileBorrower(x, genTexts=mibBuilder.loadTexts) for x in getReadersFromUrls(*kwargs.get('borrowers') or defaultBorrowers, **dict(originalMatching=False, lowcaseMatching=False)) ]
+        )
+
+        mibBuilder.setMibCompiler(
+            compiler, kwargs.get('destination') or defaultDest
         )
 
-        mibBuilder.setMibCompiler(compiler, destination)
diff --git a/pysnmp/smi/rfc1902.py b/pysnmp/smi/rfc1902.py
index 4c23c31..7fb1013 100644
--- a/pysnmp/smi/rfc1902.py
+++ b/pysnmp/smi/rfc1902.py
@@ -2,7 +2,7 @@ import sys
 from pysnmp.proto import rfc1902, rfc1905
 from pysnmp.proto.api import v2c
 from pysnmp.smi.builder import ZipMibSource
-from pysnmp.smi.compiler import addMibCompiler, defaultDest
+from pysnmp.smi.compiler import addMibCompiler
 from pysnmp.smi.error import SmiError
 from pyasn1.type.base import AbstractSimpleAsn1Item
 from pyasn1.error import PyAsn1Error
@@ -25,7 +25,7 @@ class ObjectIdentity:
         self.__args = args
         self.__kwargs = kwargs
         self.__mibSourcesToAdd = self.__modNamesToLoad = None
-        self.__asn1SourcesToAdd = None
+        self.__asn1SourcesToAdd = self.__asn1SourcesOptions = None
         self.__state  = self.stDirty
 
     #
@@ -59,12 +59,15 @@ class ObjectIdentity:
     # A gateway to MIBs manipulation routines
     #
 
-    def addMibCompiler(self, *asn1Sources, **kwargs):
+    def addAsn1MibSource(self, *asn1Sources, **kwargs):
         if self.__asn1SourcesToAdd is None:
             self.__asn1SourcesToAdd = asn1Sources
         else:
             self.__asn1SourcesToAdd += asn1Sources
-        self.__mibDir = kwargs.get('destDir', defaultDest)
+        if self.__asn1SourcesOptions:
+            self.__asn1SourcesOptions.update(kwargs)
+        else:
+            self.__asn1SourcesOptions = kwargs
         return self
 
     def addMibSource(self, *mibSources):
@@ -92,14 +95,21 @@ class ObjectIdentity:
             )
             self.__mibSourcesToAdd = None
 
-        if self.__asn1SourcesToAdd is not None:
+        if self.__asn1SourcesToAdd is None:
+            addMibCompiler(mibViewController.mibBuilder,
+                           ifAvailable=True, ifNotAdded=True)
+        else:
             debug.logger & debug.flagMIB and debug.logger('adding MIB compiler with source paths %s' % ', '.join(self.__asn1SourcesToAdd))
             addMibCompiler(
                 mibViewController.mibBuilder,
                 sources=self.__asn1SourcesToAdd,
-                destination=self.__mibDir
+                searchers=self.__asn1SourcesOptions.get('searchers'),
+                borrowers=self.__asn1SourcesOptions.get('borrowers'),
+                destination=self.__asn1SourcesOptions.get('destination'),
+                ifAvailable=self.__asn1SourcesOptions.get('ifAvailable'),
+                ifNotAdded=self.__asn1SourcesOptions.get('ifNotAdded')
             )
-            self.__asn1SourcesToAdd = self.__mibDir = None
+            self.__asn1SourcesToAdd = self.__asn1SourcesOptions = None
 
         if self.__modNamesToLoad is not None:
             debug.logger & debug.flagMIB and debug.logger('loading MIB modules %s' % ', '.join(self.__modNamesToLoad))