Add a driver for YALPT

YALPT (https://github.com/directxman12/yalpt) now support "environment
drivers" which setup and teardown an environment for the console
sessions.  This commit adds a GSSAPI environment driver so that
GSSAPI Console functionality can be used to run YALPT files.

Author: DirectXMan12

gssapi_console/yalpt_driver.py

@@ -0,0 +1,64 @@
+import pkg_resources as pkgres
+import copy
+import os
+
+class GSSAPIYalptDriver(object):
+    DRIVER_NAME = "GSSAPI"
+    BANNER = """Functions for controlling the realm are available in `REALM`.
+Mechansim: {mech} ({driver}), Realm: {realm}, User: {user}, Host: {host}"""
+
+    def __init__(self, args=None):
+        self._realm_args = {}
+
+        if args is None:
+            driver = 'krb5'
+        else:
+            args_parts = args.split(';')
+            driver = args_parts[0]
+
+            if len(args_parts) > 1:
+                realm_args_raw = args_parts[1]
+                for arg in realm_args_raw.split(','):
+                    key, raw_val = arg.split('=')
+                    self._realm_args[key] = (raw_val.lower() == 'true')
+
+        try:
+            driver_loader = next(
+                pkgres.iter_entry_points('gssapi_console.drivers',
+                                         name=driver))
+        except StopIteration:
+            raise ValueError("No such GSSAPI Console driver %s." % driver)
+
+        self._driver = driver_loader.load()()
+
+        self._saved_env = None
+        self._realm = None
+
+    def setup(self):
+        self._saved_env = copy.deepcopy(os.environ)
+        self._realm = self._driver.create_realm(self._realm_args)
+        for k, v in self._realm.env.items():
+            os.environ[k] = v
+
+        return {'REALM': self._realm}
+
+    def teardown(self):
+        if self._saved_env is not None:
+            for k in copy.deepcopy(os.environ):
+                if k in self._saved_env:
+                    os.environ[k] = self._saved_env[k]
+                else:
+                    del os.environ[k]
+
+            self._saved_env = None
+
+        self._driver.destroy_realm(self._realm)
+
+    @property
+    def banner(self):
+        return self.BANNER.format(mech=self._driver.MECH_NAME,
+                                  driver=self._driver.PROVIDER_NAME,
+                                  realm=self._realm.realm,
+                                  user=self._realm.user_princ,
+                                  host=self._realm.host_princ)
+

setup.py

@@ -29,6 +29,9 @@
         'gssapi_console.drivers': [
             'krb5 = gssapi_console.drivers:Krb5Console',
         ],
+        'yalpt.env_drivers': [
+            'gssapi = gssapi_console.yalpt_driver:GSSAPIYalptDriver',
+        ],
     },
     install_requires=[
         'gssapi',