Add a 'smart sync' option to repo sync

This option allows the user to specify a manifest server to use when
syncing. This manifest server will provide a manifest pegging each
project to a known green build. This allows developers to work on a
known good tree that is known to build and pass tests, preventing
failed builds to hamper productivity.

The manifest used is not "sticky" so as to allow subsequent
'repo sync' calls to sync to the tip of the tree.

Change-Id: Id0a24ece20f5a88034ad364b416a1dd2e394226d
diff --git a/subcmds/sync.py b/subcmds/sync.py
index ceb81ea..deff171 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -17,9 +17,11 @@
 import os
 import re
 import shutil
+import socket
 import subprocess
 import sys
 import time
+import xmlrpclib
 
 from git_command import GIT
 from project import HEAD
@@ -57,6 +59,10 @@
 if the project is currently on a topic branch, but the manifest
 revision is temporarily needed.
 
+The -s/--smart-sync option can be used to sync to a known good
+build as specified by the manifest-server element in the current
+manifest.
+
 SSH Connections
 ---------------
 
@@ -97,6 +103,9 @@
     p.add_option('-d','--detach',
                  dest='detach_head', action='store_true',
                  help='detach projects back to manifest revision')
+    p.add_option('-s', '--smart-sync',
+                 dest='smart_sync', action='store_true',
+                 help='smart sync using manifest from a known good build')
 
     g = p.add_option_group('repo Version options')
     g.add_option('--no-repo-verify',
@@ -182,6 +191,49 @@
       print >>sys.stderr, 'error: cannot combine -n and -l'
       sys.exit(1)
 
+    if opt.smart_sync:
+      if not self.manifest.manifest_server:
+        print >>sys.stderr, \
+            'error: cannot smart sync: no manifest server defined in manifest'
+        sys.exit(1)
+      try:
+        server = xmlrpclib.Server(self.manifest.manifest_server)
+        p = self.manifest.manifestProject
+        b = p.GetBranch(p.CurrentBranch)
+        branch = b.merge
+
+        env = dict(os.environ)
+        if (env.has_key('TARGET_PRODUCT') and
+            env.has_key('TARGET_BUILD_VARIANT')):
+          target = '%s-%s' % (env['TARGET_PRODUCT'],
+                              env['TARGET_BUILD_VARIANT'])
+          [success, manifest_str] = server.GetApprovedManifest(branch, target)
+        else:
+          [success, manifest_str] = server.GetApprovedManifest(branch)
+
+        if success:
+          manifest_name = "smart_sync_override.xml"
+          manifest_path = os.path.join(self.manifest.manifestProject.worktree,
+                                       manifest_name)
+          try:
+            f = open(manifest_path, 'w')
+            try:
+              f.write(manifest_str)
+              self.manifest.Override(manifest_name)
+            finally:
+              f.close()
+          except IOError:
+            print >>sys.stderr, 'error: cannot write manifest to %s' % \
+                manifest_path
+            sys.exit(1)
+        else:
+          print >>sys.stderr, 'error: %s' % manifest_str
+          sys.exit(1)
+      except socket.error:
+        print >>sys.stderr, 'error: cannot connect to manifest server %s' % (
+            self.manifest.manifest_server)
+        sys.exit(1)
+
     rp = self.manifest.repoProject
     rp.PreSync()