update_payload: Fix most of lint styling issues.

This patch fixes a lot of pylint issues in the update_engine scripts. Majority
of this changes are based on recommendation found in:
	https://www.chromium.org/chromium-os/python-style-guidelines

It is a good idea to do these changes now, because if there are many pylint
errors when performing 'repo upload', serious problems can be overshadowed by a
lot of noise and eventually cause problems.

These fixes include:
	- Fixing executable shebangs to /usr/bin/python2.
	- Fixing import-error problems by disabiling them.
	- Removing pylint disables that are not valid anymore.
	- Changing all imports to proper absolute import format.
	- Change the import of PayloadError from update_payload.PayloadError for
	  simplicity.
	- Add pydoc strings for functions and classes that were missing.

The remaining unchanged pylint problmes include:

	- The header files of these scripts are in CrOS copyright format, but the
      the cros lint hook is configured to AoSP copyright format.
	- The test* functions in unittests are not compatible with CamelCase format.

BUG=chromium:796338
TEST=unittests pass
TEST=start_devserver
TEST=cros flash
TEST=scripts/paycheck.py

Change-Id: I7eed4d1625eb7c510c7949fada120de5a6a26c7b
Reviewed-on: https://chromium-review.googlesource.com/834875
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>

1 files changed, 3 insertions, 10 deletions

diff --git a/scripts/update_payload/test_utils.py b/scripts/update_payload/test_utils.py
index 61a91f53..38712fb1 100644
--- a/scripts/update_payload/test_utils.py
+++ b/scripts/update_payload/test_utils.py
@@ -12,9 +12,9 @@ import os
 import struct
 import subprocess
 
-import common
-import payload
-import update_metadata_pb2
+from update_payload import common
+from update_payload import payload
+from update_payload import update_metadata_pb2
 
 
 class TestError(Exception):
@@ -84,7 +84,6 @@ def SignSha256(data, privkey_file_name):
   Raises:
     TestError if something goes wrong.
   """
-  # pylint: disable=E1101
   data_sha256_hash = common.SIG_ASN1_HEADER + hashlib.sha256(data).digest()
   sign_cmd = ['openssl', 'rsautl', '-sign', '-inkey', privkey_file_name]
   try:
@@ -110,8 +109,6 @@ class SignaturesGenerator(object):
       version: signature version (None means do not assign)
       data: signature binary data (None means do not assign)
     """
-    # Pylint fails to identify a member of the Signatures message.
-    # pylint: disable=E1101
     sig = self.sigs.signatures.add()
     if version is not None:
       sig.version = version
@@ -174,11 +171,9 @@ class PayloadGenerator(object):
       part_hash: the partition hash
     """
     if is_kernel:
-      # pylint: disable=E1101
       part_info = (self.manifest.new_kernel_info if is_new
                    else self.manifest.old_kernel_info)
     else:
-      # pylint: disable=E1101
       part_info = (self.manifest.new_rootfs_info if is_new
                    else self.manifest.old_rootfs_info)
     _SetMsgField(part_info, 'size', part_size)
@@ -188,7 +183,6 @@ class PayloadGenerator(object):
                    data_length=None, src_extents=None, src_length=None,
                    dst_extents=None, dst_length=None, data_sha256_hash=None):
     """Adds an InstallOperation entry."""
-    # pylint: disable=E1101
     operations = (self.manifest.kernel_install_operations if is_kernel
                   else self.manifest.install_operations)
 
@@ -293,7 +287,6 @@ class EnhancedPayloadGenerator(PayloadGenerator):
     data_offset = data_length = data_sha256_hash = None
     if data_blob is not None:
       if do_hash_data_blob:
-        # pylint: disable=E1101
         data_sha256_hash = hashlib.sha256(data_blob).digest()
       data_length, data_offset = self.AddData(data_blob)