Disable VABC if either source/target doesn't support it

If source supports VABC, delta_generator/update_engine will attempt to
use VABC. This dangerous, as the target build won't have snapuserd to
serve I/O request when device boots. Therefore, disable VABC if source
build doesn't supports it.

Test: downgrade from VABC enabled build to a build w/o VABC

Change-Id: Ie8353e00f65354c2242ee5255b6652c6b62483a4

tools/releasetools/common.py

@@ -138,6 +138,7 @@ PARTITIONS_WITH_BUILD_PROP = PARTITIONS_WITH_CARE_MAP + ['boot']
 # existing search paths.
 RAMDISK_BUILD_PROP_REL_PATHS = ['system/etc/ramdisk/build.prop']
 
+
 class ErrorCode(object):
   """Define error_codes for failures that happen during the actual
   update package installation.
@@ -226,6 +227,7 @@ def InitLogging():
 def SetHostToolLocation(tool_name, location):
   OPTIONS.host_tools[tool_name] = location
 
+
 def FindHostToolPath(tool_name):
   """Finds the path to the host tool.
 
@@ -246,6 +248,7 @@ def FindHostToolPath(tool_name):
 
   return tool_name
 
+
 def Run(args, verbose=None, **kwargs):
   """Creates and returns a subprocess.Popen object.
 
@@ -433,6 +436,13 @@ class BuildInfo(object):
   def fingerprint(self):
     return self._fingerprint
 
+  @property
+  def is_vabc(self):
+    vendor_prop = self.info_dict.get("vendor.build.prop")
+    vabc_enabled = vendor_prop and \
+        vendor_prop.GetProp("ro.virtual_ab.compression.enabled") == "true"
+    return vabc_enabled
+
   @property
   def oem_props(self):
     return self._oem_props
@@ -652,10 +662,12 @@ def ExtractFromInputFile(input_file, fn):
       raise KeyError(fn)
     return file
 
+
 class RamdiskFormat(object):
   LZ4 = 1
   GZ = 2
 
+
 def _GetRamdiskFormat(info_dict):
   if info_dict.get('lz4_ramdisks') == 'true':
     ramdisk_format = RamdiskFormat.LZ4
@@ -663,6 +675,7 @@ def _GetRamdiskFormat(info_dict):
     ramdisk_format = RamdiskFormat.GZ
   return ramdisk_format
 
+
 def LoadInfoDict(input_file, repacking=False):
   """Loads the key/value pairs from the given input target_files.
 
@@ -781,7 +794,8 @@ def LoadInfoDict(input_file, repacking=False):
     for partition in PARTITIONS_WITH_BUILD_PROP:
       fingerprint = build_info.GetPartitionFingerprint(partition)
       if fingerprint:
-        d["avb_{}_salt".format(partition)] = sha256(fingerprint.encode()).hexdigest()
+        d["avb_{}_salt".format(partition)] = sha256(
+            fingerprint.encode()).hexdigest()
   try:
     d["ab_partitions"] = read_helper("META/ab_partitions.txt").split("\n")
   except KeyError:
@@ -789,7 +803,6 @@ def LoadInfoDict(input_file, repacking=False):
   return d
 
 
-
 def LoadListFromFile(file_path):
   with open(file_path) as f:
     return f.read().splitlines()
@@ -859,7 +872,8 @@ class PartitionBuildProps(object):
     """Loads the build.prop file and builds the attributes."""
 
     if name == "boot":
-      data = PartitionBuildProps._ReadBootPropFile(input_file, ramdisk_format=ramdisk_format)
+      data = PartitionBuildProps._ReadBootPropFile(
+          input_file, ramdisk_format=ramdisk_format)
     else:
       data = PartitionBuildProps._ReadPartitionPropFile(input_file, name)
 
@@ -1371,7 +1385,8 @@ def AppendGkiSigningArgs(cmd):
 
   # Checks key_path exists, before appending --gki_signing_* args.
   if not os.path.exists(key_path):
-    raise ExternalError('gki_signing_key_path: "{}" not found'.format(key_path))
+    raise ExternalError(
+        'gki_signing_key_path: "{}" not found'.format(key_path))
 
   algorithm = OPTIONS.info_dict.get("gki_signing_algorithm")
   if key_path and algorithm:
@@ -1753,14 +1768,17 @@ def _BuildVendorBootImage(sourcedir, info_dict=None):
   if os.access(fn, os.F_OK):
     ramdisk_fragments = shlex.split(open(fn).read().rstrip("\n"))
     for ramdisk_fragment in ramdisk_fragments:
-      fn = os.path.join(sourcedir, "RAMDISK_FRAGMENTS", ramdisk_fragment, "mkbootimg_args")
+      fn = os.path.join(sourcedir, "RAMDISK_FRAGMENTS",
+                        ramdisk_fragment, "mkbootimg_args")
       cmd.extend(shlex.split(open(fn).read().rstrip("\n")))
-      fn = os.path.join(sourcedir, "RAMDISK_FRAGMENTS", ramdisk_fragment, "prebuilt_ramdisk")
+      fn = os.path.join(sourcedir, "RAMDISK_FRAGMENTS",
+                        ramdisk_fragment, "prebuilt_ramdisk")
       # Use prebuilt image if found, else create ramdisk from supplied files.
       if os.access(fn, os.F_OK):
         ramdisk_fragment_pathname = fn
       else:
-        ramdisk_fragment_root = os.path.join(sourcedir, "RAMDISK_FRAGMENTS", ramdisk_fragment)
+        ramdisk_fragment_root = os.path.join(
+            sourcedir, "RAMDISK_FRAGMENTS", ramdisk_fragment)
         ramdisk_fragment_img = _MakeRamdisk(ramdisk_fragment_root,
                                             ramdisk_format=ramdisk_format)
         ramdisk_fragment_imgs.append(ramdisk_fragment_img)
@@ -3693,7 +3711,8 @@ def GetBootImageBuildProp(boot_img, ramdisk_format=RamdiskFormat.LZ4):
   """
   tmp_dir = MakeTempDir('boot_', suffix='.img')
   try:
-    RunAndCheckOutput(['unpack_bootimg', '--boot_img', boot_img, '--out', tmp_dir])
+    RunAndCheckOutput(['unpack_bootimg', '--boot_img',
+                      boot_img, '--out', tmp_dir])
     ramdisk = os.path.join(tmp_dir, 'ramdisk')
     if not os.path.isfile(ramdisk):
       logger.warning('Unable to get boot image timestamp: no ramdisk in boot')
@@ -3704,7 +3723,8 @@ def GetBootImageBuildProp(boot_img, ramdisk_format=RamdiskFormat.LZ4):
     elif ramdisk_format == RamdiskFormat.GZ:
       with open(ramdisk, 'rb') as input_stream:
         with open(uncompressed_ramdisk, 'wb') as output_stream:
-          p2 = Run(['minigzip', '-d'], stdin=input_stream.fileno(), stdout=output_stream.fileno())
+          p2 = Run(['minigzip', '-d'], stdin=input_stream.fileno(),
+                   stdout=output_stream.fileno())
           p2.wait()
     else:
       logger.error('Only support lz4 or minigzip ramdisk format.')
@@ -3721,7 +3741,8 @@ def GetBootImageBuildProp(boot_img, ramdisk_format=RamdiskFormat.LZ4):
       prop_file = os.path.join(extracted_ramdisk, search_path)
       if os.path.isfile(prop_file):
         return prop_file
-      logger.warning('Unable to get boot image timestamp: no %s in ramdisk', search_path)
+      logger.warning(
+          'Unable to get boot image timestamp: no %s in ramdisk', search_path)
 
     return None
 
@@ -3754,7 +3775,8 @@ def GetBootImageTimestamp(boot_img):
     timestamp = props.GetProp('ro.bootimage.build.date.utc')
     if timestamp:
       return int(timestamp)
-    logger.warning('Unable to get boot image timestamp: ro.bootimage.build.date.utc is undefined')
+    logger.warning(
+        'Unable to get boot image timestamp: ro.bootimage.build.date.utc is undefined')
     return None
 
   except ExternalError as e:

tools/releasetools/ota_from_target_files.py

@@ -1051,15 +1051,18 @@ def GenerateAbOtaPackage(target_file, output_file, source_file=None):
         "META/ab_partitions.txt is required for ab_update."
     target_info = common.BuildInfo(OPTIONS.target_info_dict, OPTIONS.oem_dicts)
     source_info = common.BuildInfo(OPTIONS.source_info_dict, OPTIONS.oem_dicts)
-    vendor_prop = source_info.info_dict.get("vendor.build.prop")
+    # If source supports VABC, delta_generator/update_engine will attempt to
-    vabc_used = vendor_prop and \
+    # use VABC. This dangerous, as the target build won't have snapuserd to
-        vendor_prop.GetProp("ro.virtual_ab.compression.enabled") == "true" and \
+    # serve I/O request when device boots. Therefore, disable VABC if source
-        not OPTIONS.disable_vabc
+    # build doesn't supports it.
-    if vabc_used:
+    if not source_info.is_vabc or not target_info.is_vabc:
+      OPTIONS.disable_vabc = True
+    if not OPTIONS.disable_vabc:
       # TODO(zhangkelvin) Remove this once FEC on VABC is supported
       logger.info("Virtual AB Compression enabled, disabling FEC")
       OPTIONS.disable_fec_computation = True
       OPTIONS.disable_verity_computation = True
+
   else:
     assert "ab_partitions" in OPTIONS.info_dict, \
         "META/ab_partitions.txt is required for ab_update."