Add compare_versions method to common_lib/utils

Signed-off-by: John Huang <johnhuang@google.com>



git-svn-id: http://test.kernel.org/svn/autotest/trunk@4442 592f7852-d20e-0410-864c-8624ca9c26a4
diff --git a/client/common_lib/utils.py b/client/common_lib/utils.py
index 996a240..2ceca35 100644
--- a/client/common_lib/utils.py
+++ b/client/common_lib/utils.py
@@ -1268,3 +1268,21 @@
 
     system('%s %s' % (configure, ' '.join(args)))
 
+
+def compare_versions(ver1, ver2):
+    """Compares two dot-delimited version strings.
+
+    Version number comparison between ver1 and ver2 of the form 'x.y.z'
+
+    Args:
+        ver1: dot-delimited string in 'x.y.z' form
+        ver2: dot-delimited string in 'x.y.z' form
+
+    Returns:
+        int:  1 if ver1 >  ver2
+              0 if ver1 == ver2
+             -1 if ver1 <  ver2
+    """
+    v1 = [int(x) for x in ver1.split('.')]
+    v2 = [int(x) for x in ver2.split('.')]
+    return cmp(v1, v2)