releasetools: Move the AVB salt setup into common.LoadInfoDict().

We used to do this in add_img_to_target_files.AddImagesToTargetFiles(),
which didn't cover the path when calling from make_recovery_patch. As a
result, /system/bin/install-recovery.sh contains different SHA values
from the actual images.

Test: Set up aosp_bullhead to use AVB. `m dist`, then run the following
      command to verify the generated install-recovery.sh.

  $ ./build/make/tools/releasetools/validate_target_files.py \
      out/dist/aosp_bullhead-target_files-eng.zip

Change-Id: Id7be8fb17072252fcd4d08db2057b8c4af053376

tools/releasetools/add_img_to_target_files.py

@@ -46,7 +46,6 @@ Usage:  add_img_to_target_files [flag] target_files
 from __future__ import print_function
 
 import datetime
-import hashlib
 import os
 import shlex
 import shutil
@@ -668,17 +667,6 @@ def AddImagesToTargetFiles(filename):
 
   has_recovery = (OPTIONS.info_dict.get("no_recovery") != "true")
 
-  if OPTIONS.info_dict.get("avb_enable") == "true":
-    fp = None
-    if "build.prop" in OPTIONS.info_dict:
-      build_prop = OPTIONS.info_dict["build.prop"]
-      if "ro.build.fingerprint" in build_prop:
-        fp = build_prop["ro.build.fingerprint"]
-      elif "ro.build.thumbprint" in build_prop:
-        fp = build_prop["ro.build.thumbprint"]
-    if fp:
-      OPTIONS.info_dict["avb_salt"] = hashlib.sha256(fp).hexdigest()
-
   # A map between partition names and their paths, which could be used when
   # generating AVB vbmeta image.
   partitions = dict()

tools/releasetools/common.py

@@ -31,12 +31,10 @@ import tempfile
 import threading
 import time
 import zipfile
+from hashlib import sha1, sha256
 
 import blockimgdiff
 
-from hashlib import sha1 as sha1
-
-
 class Options(object):
   def __init__(self):
     platform_search_path = {
@@ -259,6 +257,20 @@ def LoadInfoDict(input_file, input_dir=None):
 
   d["build.prop"] = LoadBuildProp(read_helper, 'SYSTEM/build.prop')
   d["vendor.build.prop"] = LoadBuildProp(read_helper, 'VENDOR/build.prop')
+
+  # Set up the salt (based on fingerprint or thumbprint) that will be used when
+  # adding AVB footer.
+  if d.get("avb_enable") == "true":
+    fp = None
+    if "build.prop" in d:
+      build_prop = d["build.prop"]
+      if "ro.build.fingerprint" in build_prop:
+        fp = build_prop["ro.build.fingerprint"]
+      elif "ro.build.thumbprint" in build_prop:
+        fp = build_prop["ro.build.thumbprint"]
+    if fp:
+      d["avb_salt"] = sha256(fp).hexdigest()
+
   return d