From 962dfdcdaca8255fec5f7197044b7a7c3749a1bf Mon Sep 17 00:00:00 2001
From: Tao Bao <tbao@google.com>
Date: Thu, 14 Apr 2016 15:58:05 -0700
Subject: [PATCH] Skip verifying the partition with no changed blocks.

For incremental BBOTAs, commit [1] changed to verify only the touched
blocks to reduce the update time. This CL fixes the bug when there's no
changed block between the two builds.

[1]: commit d522bdc9edbf64d15a59c6924853b2e2c8c39e90

Bug: 27813356
Bug: 28195498
Change-Id: Ia752d3cf034c544517458ed15df509d4596e21fa
(cherry picked from commit f9efe284a4f8f1e40ea634c5e86f3d5e9935d8c8)
---
 tools/releasetools/common.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index f68596b7b..92af54708 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1472,8 +1472,12 @@ class BlockDifference(object):
 
   def WriteVerifyScript(self, script, touched_blocks_only=False):
     partition = self.partition
+
+    # full OTA
     if not self.src:
       script.Print("Image %s will be patched unconditionally." % (partition,))
+
+    # incremental OTA
     else:
       if touched_blocks_only and self.version >= 3:
         ranges = self.touched_src_ranges
@@ -1481,6 +1485,11 @@ class BlockDifference(object):
       else:
         ranges = self.src.care_map.subtract(self.src.clobbered_blocks)
         expected_sha1 = self.src.TotalSha1()
+
+      # No blocks to be checked, skipping.
+      if not ranges:
+        return
+
       ranges_str = ranges.to_string_raw()
       if self.version >= 4:
         script.AppendExtra(('if (range_sha1("%s", "%s") == "%s" || '