From c2d6bf758845076eca6eb71af09df77165993270 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Javier=20Jard=C3=B3n?= <javier.jardon@codethink.co.uk>
Date: Mon, 2 Mar 2015 19:14:57 +0000
Subject: morphlib/sourceresolver.py: Check and parse VERSION file

Only fail if:
- VERSION file exists
- and its a yaml file
- and its a dict
- and has the key 'version'
- and the contents of the key 'version' is an int
- and that int is in the list of non_supported_versions (empty
  at the moment)
---
 morphlib/sourceresolver.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/morphlib/sourceresolver.py b/morphlib/sourceresolver.py
index f571d76b..387d2e0d 100644
--- a/morphlib/sourceresolver.py
+++ b/morphlib/sourceresolver.py
@@ -21,6 +21,7 @@ import os
 import pylru
 import shutil
 import tempfile
+import yaml
 
 import cliapp
 
@@ -31,6 +32,7 @@ tree_cache_filename = 'trees.cache.pickle'
 buildsystem_cache_size = 10000
 buildsystem_cache_filename = 'detected-chunk-buildsystems.cache.pickle'
 
+not_supported_versions = []
 
 class PickleCacheManager(object): # pragma: no cover
     '''Cache manager for PyLRU that reads and writes to Pickle files.
@@ -89,6 +91,11 @@ class MorphologyNotFoundError(SourceResolverError): # pragma: no cover
         SourceResolverError.__init__(
             self, "Couldn't find morphology: %s" % filename)
 
+class UnknownVersionError(SourceResolverError): # pragma: no cover
+    def __init__(self, version):
+        SourceResolverError.__init__(
+            self, "Definitions format version %s is not supported" % version)
+
 
 class SourceResolver(object):
     '''Provides a way of resolving the set of sources for a given system.
@@ -338,6 +345,22 @@ class SourceResolver(object):
         loader.set_defaults(morph)
         return morph
 
+    def _check_version_file(self,definitions_repo,
+                            definitions_absref): # pragma: no cover
+        version_file = self._get_file_contents(
+            definitions_repo, definitions_absref, 'VERSION')
+
+        if version_file is None:
+            return
+
+        try:
+            version = yaml.safe_load(version_file)['version']
+        except (yaml.error.YAMLError, KeyError, TypeError):
+            version = 0
+
+        if version in not_supported_versions:
+            raise UnknownVersionError(version)
+
     def _process_definitions_with_children(self, system_filenames,
                                            definitions_repo,
                                            definitions_ref,
@@ -347,6 +370,8 @@ class SourceResolver(object):
         definitions_queue = collections.deque(system_filenames)
         chunk_queue = set()
 
+        self._check_version_file(definitions_repo, definitions_absref)
+
         while definitions_queue:
             filename = definitions_queue.popleft()
 
-- 
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