From d522bdc9edbf64d15a59c6924853b2e2c8c39e90 Mon Sep 17 00:00:00 2001
From: Tao Bao <tbao@google.com>
Date: Tue, 12 Apr 2016 15:53:16 -0700
Subject: [PATCH] releasetools: Only verify the blocks to be touched.

For incremental BBOTAs, we used to verify the integrity of all the
blocks in the source partition. In order to reduce the time cost under
recovery, this CL changes to only verify the blocks that will be touched
in the given OTA package (BBOTA >= 3 only). This is a trade-off between
performance and reliability.

Bug: 27813356
Change-Id: I3975ae6f461f0f7e58d24f1df7df46a449d2988b
---
 tools/releasetools/blockimgdiff.py          | 13 +++++++++++++
 tools/releasetools/common.py                | 15 +++++++++++----
 tools/releasetools/ota_from_target_files.py |  4 ++--
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 625dca2c8f..d49112fd16 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -272,6 +272,8 @@ class BlockImageDiff(object):
     self.src_basenames = {}
     self.src_numpatterns = {}
     self._max_stashed_size = 0
+    self.touched_src_ranges = RangeSet()
+    self.touched_src_sha1 = None
 
     assert version in (1, 2, 3, 4)
 
@@ -373,6 +375,7 @@ class BlockImageDiff(object):
           else:
             stashes[sh] = 1
             stashed_blocks += sr.size()
+            self.touched_src_ranges = self.touched_src_ranges.union(sr)
             out.append("stash %s %s\n" % (sh, sr.to_string_raw()))
 
       if stashed_blocks > max_stashed_blocks:
@@ -479,6 +482,9 @@ class BlockImageDiff(object):
               if temp_stash_usage > max_stashed_blocks:
                 max_stashed_blocks = temp_stash_usage
 
+            self.touched_src_ranges = self.touched_src_ranges.union(
+                xf.src_ranges)
+
             out.append("%s %s %s %s\n" % (
                 xf.style,
                 self.HashBlocks(self.tgt, xf.tgt_ranges),
@@ -502,6 +508,9 @@ class BlockImageDiff(object):
             if temp_stash_usage > max_stashed_blocks:
               max_stashed_blocks = temp_stash_usage
 
+          self.touched_src_ranges = self.touched_src_ranges.union(
+              xf.src_ranges)
+
           out.append("%s %d %d %s %s %s %s\n" % (
               xf.style,
               xf.patch_start, xf.patch_len,
@@ -537,6 +546,10 @@ class BlockImageDiff(object):
                    self.tgt.blocksize, max_allowed, cache_size,
                    stash_threshold)
 
+    if self.version >= 3:
+      self.touched_src_sha1 = self.HashBlocks(
+          self.src, self.touched_src_ranges)
+
     # Zero out extended blocks as a workaround for bug 20881595.
     if self.tgt.extended:
       out.append("zero %s\n" % (self.tgt.extended.to_string_raw(),))
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 98e3d0438c..a07643e664 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1314,6 +1314,8 @@ class BlockDifference(object):
     self.path = os.path.join(tmpdir, partition)
     b.Compute(self.path)
     self._required_cache = b.max_stashed_size
+    self.touched_src_ranges = b.touched_src_ranges
+    self.touched_src_sha1 = b.touched_src_sha1
 
     if src is None:
       _, self.device = GetTypeAndDevice("/" + partition, OPTIONS.info_dict)
@@ -1357,26 +1359,31 @@ class BlockDifference(object):
                        self.device))
     script.AppendExtra("")
 
-  def WriteVerifyScript(self, script):
+  def WriteVerifyScript(self, script, touched_blocks_only=False):
     partition = self.partition
     if not self.src:
       script.Print("Image %s will be patched unconditionally." % (partition,))
     else:
-      ranges = self.src.care_map.subtract(self.src.clobbered_blocks)
+      if touched_blocks_only and self.version >= 3:
+        ranges = self.touched_src_ranges
+        expected_sha1 = self.touched_src_sha1
+      else:
+        ranges = self.src.care_map.subtract(self.src.clobbered_blocks)
+        expected_sha1 = self.src.TotalSha1()
       ranges_str = ranges.to_string_raw()
       if self.version >= 4:
         script.AppendExtra(('if (range_sha1("%s", "%s") == "%s" || '
                             'block_image_verify("%s", '
                             'package_extract_file("%s.transfer.list"), '
                             '"%s.new.dat", "%s.patch.dat")) then') % (
-                            self.device, ranges_str, self.src.TotalSha1(),
+                            self.device, ranges_str, expected_sha1,
                             self.device, partition, partition, partition))
       elif self.version == 3:
         script.AppendExtra(('if (range_sha1("%s", "%s") == "%s" || '
                             'block_image_verify("%s", '
                             'package_extract_file("%s.transfer.list"), '
                             '"%s.new.dat", "%s.patch.dat")) then') % (
-                            self.device, ranges_str, self.src.TotalSha1(),
+                            self.device, ranges_str, expected_sha1,
                             self.device, partition, partition, partition))
       else:
         script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' % (
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 4d0d8a5b12..861c4850de 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -996,9 +996,9 @@ else
 """ % bcb_dev)
 
   # Verify the existing partitions.
-  system_diff.WriteVerifyScript(script)
+  system_diff.WriteVerifyScript(script, touched_blocks_only=True)
   if vendor_diff:
-    vendor_diff.WriteVerifyScript(script)
+    vendor_diff.WriteVerifyScript(script, touched_blocks_only=True)
 
   script.Comment("---- start making changes here ----")