VMAX Truncate Storage Group Name

In the VMAX driver, it generates a storage group name using
the short host name, pool name, etc. However the storage
group name has an upper limit of 64 characters. So it fails
if the length of the name exceeds the limit. This patch
fixes it by truncating the name to fix within the limit.

Change-Id: I18258933591a389691a7b33af2d30a40bb34f09c
Closes-Bug: #1501925

cinder/volume/drivers/emc/emc_vmax_utils.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import datetime
+import hashlib
 import random
 import re
 from xml.dom import minidom
@@ -629,12 +630,12 @@ class EMCVMAXUtils(object):
         shortHostName = None
 
         hostArray = hostName.split('.')
-        if len(hostArray) > 2:
+        if len(hostArray) > 1:
             shortHostName = hostArray[0]
         else:
             shortHostName = hostName
 
-        return shortHostName
+        return self.generate_unique_trunc_host(shortHostName)
 
     def get_instance_name(self, classname, bindings):
         """Get the instance from the classname and bindings.
@@ -2343,3 +2344,35 @@ class EMCVMAXUtils(object):
                       {'volume': volumeInstance.path, 'rc': rc, 'ret': ret})
             memberVolumes = ret['OutElements']
         return memberVolumes
+
+    def generate_unique_trunc_host(self, hostName):
+        """Create a unique short host name under 40 chars
+
+        :param sgName: long storage group name
+        :returns: truncated storage group name
+        """
+        if hostName and len(hostName) > 38:
+            hostName = hostName.lower()
+            m = hashlib.md5()
+            m.update(hostName.encode('utf-8'))
+            uuid = m.hexdigest()
+            return(
+                ("%(host)s%(uuid)s"
+                 % {'host': hostName[-6:],
+                    'uuid': uuid}))
+        else:
+            return hostName
+
+    def generate_unique_trunc_pool(self, poolName):
+        """Create a unique pool name under 16 chars
+
+        :param poolName: long pool name
+        :returns: truncated pool name
+        """
+        if poolName and len(poolName) > 16:
+            return (
+                ("%(first)s_%(last)s"
+                 % {'first': poolName[:8],
+                    'last': poolName[-7:]}))
+        else:
+            return poolName