Calculate the vbmeta digest when building images

Calculate the vbmeta digest if the device builds vbmeta image. The
digest will used later to determine the build fingerprint in new
format.

One sample usage is the ota package generation, where we put the
build fingerprint in the ota metadata. But we don't have the runtime
vbmeta digest provided the bootloader.

Bug: 186786987
Test: unit tests
Change-Id: If572e2b973e295a6c95a9e23a65bb20b3afbf1b0

tools/releasetools/verity_utils.py

@@ -26,6 +26,7 @@ import logging
 import os.path
 import shlex
 import struct
+import sys
 
 import common
 import sparse_img
@@ -739,6 +740,30 @@ def GetDiskUsage(path):
   return int(output.split()[0]) * 1024
 
 
+def CalculateVbmetaDigest(extracted_dir, avbtool):
+  """Calculates the vbmeta digest of the images in the extracted target_file"""
+
+  images_dir = common.MakeTempDir()
+  for name in ("PREBUILT_IMAGES", "RADIO", "IMAGES"):
+    path = os.path.join(extracted_dir, name)
+    if not os.path.exists(path):
+      continue
+
+    # Create symlink for image files under PREBUILT_IMAGES, RADIO and IMAGES,
+    # and put them into one directory.
+    for filename in os.listdir(path):
+      if not filename.endswith(".img"):
+        continue
+      symlink_path = os.path.join(images_dir, filename)
+      # The files in latter directory overwrite the existing links
+      common.RunAndCheckOutput(
+        ['ln', '-sf', os.path.join(path, filename), symlink_path])
+
+  cmd = [avbtool, "calculate_vbmeta_digest", "--image",
+         os.path.join(images_dir, 'vbmeta.img')]
+  return common.RunAndCheckOutput(cmd)
+
+
 def main(argv):
   if len(argv) != 2:
     print(__doc__)