lib/python/debian_support.py: Normalize version numbers before comparison

In theory, this allows us to use the data for unstable for volatile
and backports.org.  However, more testing is required if this is
indeed effective, and volatile does not actually use the version
number scheme assumed in this change.

git-svn-id: svn+ssh://svn.debian.org/svn/secure-testing@10579 e39458fd-73e7-0310-bf30-c45bca0a0e42

1 files changed, 16 insertions, 4 deletions

diff --git a/lib/python/debian_support.py b/lib/python/debian_support.py
index 827a7a49fb..4c1f758888 100644
--- a/lib/python/debian_support.py
+++ b/lib/python/debian_support.py
@@ -55,8 +55,14 @@ class ParseError(Exception):
         file.write("%s:%d: %s\n" % (self.filename, self.lineno, self.msg))
         file.flush()
 
+# This regular expression is used to strip ~bpo1 and ~volatile1 from
+# version numbers before they are compared.
+_version_normalize_regexp = re.compile(r"~(?:bpo|volatile)[0-9.+]+$")
+
 class Version:
-    """Version class which uses the original APT comparison algorithm."""
+    """Version class which uses the original APT comparison algorithm.
+
+    ~bpo and ~volatile suffixes are ignored."""
 
     def __init__(self, version):
         """Creates a new Version object."""
@@ -67,6 +73,7 @@ class Version:
             assert t == types.StringType, `version`
         assert version <> ""
         self.__asString = version
+        self.__forCompare = _version_normalize_regexp.sub("", version)
 
     def __str__(self):
         return self.__asString
@@ -75,10 +82,15 @@ class Version:
         return 'Version(%s)' % `self.__asString`
 
     def __cmp__(self, other):
-        return apt_pkg.VersionCompare(self.__asString, other.__asString)
+        return apt_pkg.VersionCompare(self.__forCompare, other.__forCompare)
 
-
-version_compare = apt_pkg.VersionCompare
+def version_compare(a, b, vc = apt_pkg.VersionCompare):
+    """Compares two versions according to the Debian algorithm.
+    
+    ~bpo and ~volatile suffixes are ignored."""
+    a = _version_normalize_regexp.sub("", a)
+    b = _version_normalize_regexp.sub("", b)
+    return vc(a, b)
 
 class PackageFile:
     """A Debian package file.