diff --git a/tools/releasetools/add_img_to_target_files.py b/tools/releasetools/add_img_to_target_files.py
index 8bbe452..97ed873 100755
--- a/tools/releasetools/add_img_to_target_files.py
+++ b/tools/releasetools/add_img_to_target_files.py
@@ -55,14 +55,14 @@
     return
 
   def output_sink(fn, data):
-     ofile = open(os.path.join(OPTIONS.input_tmp,"SYSTEM",fn), "w")
-     ofile.write(data)
-     ofile.close()
+    ofile = open(os.path.join(OPTIONS.input_tmp, "SYSTEM", fn), "w")
+    ofile.write(data)
+    ofile.close()
 
   if OPTIONS.rebuild_recovery:
-    print("Building new recovery patch")
-    common.MakeRecoveryPatch(OPTIONS.input_tmp, output_sink, recovery_img, boot_img,
-                             info_dict=OPTIONS.info_dict)
+    print "Building new recovery patch"
+    common.MakeRecoveryPatch(OPTIONS.input_tmp, output_sink, recovery_img,
+                             boot_img, info_dict=OPTIONS.info_dict)
 
   block_list = common.MakeTempFile(prefix="system-blocklist-", suffix=".map")
   imgname = BuildSystem(OPTIONS.input_tmp, OPTIONS.info_dict,
@@ -88,7 +88,7 @@
 
   block_list = common.MakeTempFile(prefix="vendor-blocklist-", suffix=".map")
   imgname = BuildVendor(OPTIONS.input_tmp, OPTIONS.info_dict,
-                     block_list=block_list)
+                        block_list=block_list)
   common.ZipWrite(output_zip, imgname, prefix + "vendor.img")
   common.ZipWrite(output_zip, block_list, prefix + "vendor.map")
 
@@ -110,18 +110,18 @@
   try:
     os.symlink(os.path.join(input_dir, what.upper()),
                os.path.join(input_dir, what))
-  except OSError, e:
-      # bogus error on my mac version?
-      #   File "./build/tools/releasetools/img_from_target_files", line 86, in AddSystem
-      #     os.path.join(OPTIONS.input_tmp, "system"))
-      # OSError: [Errno 17] File exists
-    if (e.errno == errno.EEXIST):
+  except OSError as e:
+    # bogus error on my mac version?
+    #   File "./build/tools/releasetools/img_from_target_files"
+    #     os.path.join(OPTIONS.input_tmp, "system"))
+    # OSError: [Errno 17] File exists
+    if e.errno == errno.EEXIST:
       pass
 
   image_props = build_image.ImagePropFromGlobalDict(info_dict, what)
   fstab = info_dict["fstab"]
   if fstab:
-    image_props["fs_type" ] = fstab["/" + what].fs_type
+    image_props["fs_type"] = fstab["/" + what].fs_type
 
   if what == "system":
     fs_config_prefix = ""
@@ -130,10 +130,12 @@
 
   fs_config = os.path.join(
       input_dir, "META/" + fs_config_prefix + "filesystem_config.txt")
-  if not os.path.exists(fs_config): fs_config = None
+  if not os.path.exists(fs_config):
+    fs_config = None
 
   fc_config = os.path.join(input_dir, "BOOT/RAMDISK/file_contexts")
-  if not os.path.exists(fc_config): fc_config = None
+  if not os.path.exists(fc_config):
+    fc_config = None
 
   succ = build_image.BuildImage(os.path.join(input_dir, what),
                                 image_props, img,
@@ -173,7 +175,7 @@
 
   fstab = OPTIONS.info_dict["fstab"]
   if fstab:
-    image_props["fs_type" ] = fstab["/data"].fs_type
+    image_props["fs_type"] = fstab["/data"].fs_type
   succ = build_image.BuildImage(user_dir, image_props, img.name)
   assert succ, "build userdata.img image failed"
 
@@ -210,7 +212,7 @@
 
   fstab = OPTIONS.info_dict["fstab"]
   if fstab:
-    image_props["fs_type" ] = fstab["/cache"].fs_type
+    image_props["fs_type"] = fstab["/cache"].fs_type
   succ = build_image.BuildImage(user_dir, image_props, img.name)
   assert succ, "build cache.img image failed"
 
@@ -289,7 +291,7 @@
   output_zip.close()
 
 def main(argv):
-  def option_handler(o, a):
+  def option_handler(o, _):
     if o in ("-a", "--add_missing"):
       OPTIONS.add_missing = True
     elif o in ("-r", "--rebuild_recovery",):
@@ -298,12 +300,10 @@
       return False
     return True
 
-  args = common.ParseOptions(argv, __doc__,
-                             extra_opts="ar",
-                             extra_long_opts=["add_missing",
-                                              "rebuild_recovery",
-                                              ],
-                             extra_option_handler=option_handler)
+  args = common.ParseOptions(
+      argv, __doc__, extra_opts="ar",
+      extra_long_opts=["add_missing", "rebuild_recovery"],
+      extra_option_handler=option_handler)
 
 
   if len(args) != 1:
@@ -317,7 +317,7 @@
   try:
     common.CloseInheritedPipes()
     main(sys.argv[1:])
-  except common.ExternalError, e:
+  except common.ExternalError as e:
     print
     print "   ERROR: %s" % (e,)
     print
diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 5b5c4cc..75379cd 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -20,17 +20,17 @@
 import itertools
 import multiprocessing
 import os
-import pprint
 import re
 import subprocess
-import sys
 import threading
 import tempfile
 
-from rangelib import *
+from rangelib import RangeSet
+
 
 __all__ = ["EmptyImage", "DataImage", "BlockImageDiff"]
 
+
 def compute_patch(src, tgt, imgdiff=False):
   srcfd, srcfile = tempfile.mkstemp(prefix="src-")
   tgtfd, tgtfile = tempfile.mkstemp(prefix="tgt-")
@@ -69,7 +69,16 @@
     except OSError:
       pass
 
-class EmptyImage(object):
+
+class Image(object):
+  def ReadRangeSet(self, ranges):
+    raise NotImplementedError
+
+  def TotalSha1(self):
+    raise NotImplementedError
+
+
+class EmptyImage(Image):
   """A zero-length image."""
   blocksize = 4096
   care_map = RangeSet()
@@ -81,7 +90,7 @@
     return sha1().hexdigest()
 
 
-class DataImage(object):
+class DataImage(Image):
   """An image wrapped around a single string of data."""
 
   def __init__(self, data, trim=False, pad=False):
@@ -126,9 +135,7 @@
     return [self.data[s*self.blocksize:e*self.blocksize] for (s, e) in ranges]
 
   def TotalSha1(self):
-    if not hasattr(self, "sha1"):
-      self.sha1 = sha1(self.data).hexdigest()
-    return self.sha1
+    return sha1(self.data).hexdigest()
 
 
 class Transfer(object):
@@ -196,9 +203,13 @@
   def __init__(self, tgt, src=None, threads=None, version=3):
     if threads is None:
       threads = multiprocessing.cpu_count() // 2
-      if threads == 0: threads = 1
+      if threads == 0:
+        threads = 1
     self.threads = threads
     self.version = version
+    self.transfers = []
+    self.src_basenames = {}
+    self.src_numpatterns = {}
 
     assert version in (1, 2, 3)
 
@@ -247,7 +258,7 @@
     self.ComputePatches(prefix)
     self.WriteTransfers(prefix)
 
-  def HashBlocks(self, source, ranges):
+  def HashBlocks(self, source, ranges): # pylint: disable=no-self-use
     data = source.ReadRangeSet(ranges)
     ctx = sha1()
 
@@ -300,7 +311,7 @@
       free_string = []
 
       if self.version == 1:
-        src_string = xf.src_ranges.to_string_raw()
+        src_str = xf.src_ranges.to_string_raw()
       elif self.version >= 2:
 
         #   <# blocks> <src ranges>
@@ -310,7 +321,7 @@
         #   <# blocks> - <stash refs...>
 
         size = xf.src_ranges.size()
-        src_string = [str(size)]
+        src_str = [str(size)]
 
         unstashed_src_ranges = xf.src_ranges
         mapped_stashes = []
@@ -322,10 +333,10 @@
           sr = xf.src_ranges.map_within(sr)
           mapped_stashes.append(sr)
           if self.version == 2:
-            src_string.append("%d:%s" % (sid, sr.to_string_raw()))
+            src_str.append("%d:%s" % (sid, sr.to_string_raw()))
           else:
             assert sh in stashes
-            src_string.append("%s:%s" % (sh, sr.to_string_raw()))
+            src_str.append("%s:%s" % (sh, sr.to_string_raw()))
             stashes[sh] -= 1
             if stashes[sh] == 0:
               free_string.append("free %s\n" % (sh))
@@ -333,17 +344,17 @@
           heapq.heappush(free_stash_ids, sid)
 
         if unstashed_src_ranges:
-          src_string.insert(1, unstashed_src_ranges.to_string_raw())
+          src_str.insert(1, unstashed_src_ranges.to_string_raw())
           if xf.use_stash:
             mapped_unstashed = xf.src_ranges.map_within(unstashed_src_ranges)
-            src_string.insert(2, mapped_unstashed.to_string_raw())
+            src_str.insert(2, mapped_unstashed.to_string_raw())
             mapped_stashes.append(mapped_unstashed)
             self.AssertPartition(RangeSet(data=(0, size)), mapped_stashes)
         else:
-          src_string.insert(1, "-")
+          src_str.insert(1, "-")
           self.AssertPartition(RangeSet(data=(0, size)), mapped_stashes)
 
-        src_string = " ".join(src_string)
+        src_str = " ".join(src_str)
 
       # all versions:
       #   zero <rangeset>
@@ -356,14 +367,14 @@
       #   move <src rangeset> <tgt rangeset>
       #
       # version 2:
-      #   bsdiff patchstart patchlen <tgt rangeset> <src_string>
-      #   imgdiff patchstart patchlen <tgt rangeset> <src_string>
-      #   move <tgt rangeset> <src_string>
+      #   bsdiff patchstart patchlen <tgt rangeset> <src_str>
+      #   imgdiff patchstart patchlen <tgt rangeset> <src_str>
+      #   move <tgt rangeset> <src_str>
       #
       # version 3:
-      #   bsdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_string>
-      #   imgdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_string>
-      #   move hash <tgt rangeset> <src_string>
+      #   bsdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_str>
+      #   imgdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_str>
+      #   move hash <tgt rangeset> <src_str>
 
       tgt_size = xf.tgt_ranges.size()
 
@@ -383,12 +394,12 @@
           elif self.version == 2:
             out.append("%s %s %s\n" % (
                 xf.style,
-                xf.tgt_ranges.to_string_raw(), src_string))
+                xf.tgt_ranges.to_string_raw(), src_str))
           elif self.version >= 3:
             out.append("%s %s %s %s\n" % (
                 xf.style,
                 self.HashBlocks(self.tgt, xf.tgt_ranges),
-                xf.tgt_ranges.to_string_raw(), src_string))
+                xf.tgt_ranges.to_string_raw(), src_str))
           total += tgt_size
       elif xf.style in ("bsdiff", "imgdiff"):
         performs_read = True
@@ -401,14 +412,14 @@
         elif self.version == 2:
           out.append("%s %d %d %s %s\n" % (
               xf.style, xf.patch_start, xf.patch_len,
-              xf.tgt_ranges.to_string_raw(), src_string))
+              xf.tgt_ranges.to_string_raw(), src_str))
         elif self.version >= 3:
           out.append("%s %d %d %s %s %s %s\n" % (
               xf.style,
               xf.patch_start, xf.patch_len,
               self.HashBlocks(self.src, xf.src_ranges),
               self.HashBlocks(self.tgt, xf.tgt_ranges),
-              xf.tgt_ranges.to_string_raw(), src_string))
+              xf.tgt_ranges.to_string_raw(), src_str))
         total += tgt_size
       elif xf.style == "zero":
         assert xf.tgt_ranges
@@ -417,7 +428,7 @@
           out.append("%s %s\n" % (xf.style, to_zero.to_string_raw()))
           total += to_zero.size()
       else:
-        raise ValueError, "unknown transfer style '%s'\n" % (xf.style,)
+        raise ValueError("unknown transfer style '%s'\n" % xf.style)
 
       if free_string:
         out.append("".join(free_string))
@@ -527,11 +538,13 @@
 
       patches = [None] * patch_num
 
+      # TODO: Rewrite with multiprocessing.ThreadPool?
       lock = threading.Lock()
       def diff_worker():
         while True:
           with lock:
-            if not diff_q: return
+            if not diff_q:
+              return
             tgt_size, src, tgt, xf, patchnum = diff_q.pop()
           patch = compute_patch(src, tgt, imgdiff=(xf.style == "imgdiff"))
           size = len(patch)
@@ -543,7 +556,7 @@
                     xf.tgt_name + " (from " + xf.src_name + ")")))
 
       threads = [threading.Thread(target=diff_worker)
-                 for i in range(self.threads)]
+                 for _ in range(self.threads)]
       for th in threads:
         th.start()
       while threads:
@@ -670,8 +683,6 @@
     stash_size = 0
 
     for xf in self.transfers:
-      lost = 0
-      size = xf.src_ranges.size()
       for u in xf.goes_before.copy():
         # xf should go before u
         if xf.order < u.order:
@@ -737,7 +748,8 @@
       # Put all sinks at the end of the sequence.
       while True:
         sinks = [u for u in G if not u.outgoing]
-        if not sinks: break
+        if not sinks:
+          break
         for u in sinks:
           s2.appendleft(u)
           del G[u]
@@ -747,14 +759,16 @@
       # Put all the sources at the beginning of the sequence.
       while True:
         sources = [u for u in G if not u.incoming]
-        if not sources: break
+        if not sources:
+          break
         for u in sources:
           s1.append(u)
           del G[u]
           for iu in u.outgoing:
             del iu.incoming[u]
 
-      if not G: break
+      if not G:
+        break
 
       # Find the "best" vertex to put next.  "Best" is the one that
       # maximizes the net difference in source blocks saved we get by
@@ -792,7 +806,8 @@
     print("Generating digraph...")
     for a in self.transfers:
       for b in self.transfers:
-        if a is b: continue
+        if a is b:
+          continue
 
         # If the blocks written by A are read by B, then B needs to go before A.
         i = a.tgt_ranges.intersect(b.src_ranges)
@@ -807,7 +822,6 @@
           a.goes_after[b] = size
 
   def FindTransfers(self):
-    self.transfers = []
     empty = RangeSet()
     for tgt_fn, tgt_ranges in self.tgt.file_map.items():
       if tgt_fn == "__ZERO":
@@ -847,9 +861,6 @@
       Transfer(tgt_fn, None, tgt_ranges, empty, "new", self.transfers)
 
   def AbbreviateSourceNames(self):
-    self.src_basenames = {}
-    self.src_numpatterns = {}
-
     for k in self.src.file_map.keys():
       b = os.path.basename(k)
       self.src_basenames[b] = k
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index 55f0058..359489f 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -72,14 +72,15 @@
   """
   success, verity_tree_size = GetVerityTreeSize(partition_size)
   if not success:
-    return 0;
+    return 0
   success, verity_metadata_size = GetVerityMetadataSize(partition_size)
   if not success:
     return 0
   return partition_size - verity_tree_size - verity_metadata_size
 
 def BuildVerityTree(sparse_image_path, verity_image_path, prop_dict):
-  cmd = ("build_verity_tree -A %s %s %s" % (FIXED_SALT, sparse_image_path, verity_image_path))
+  cmd = "build_verity_tree -A %s %s %s" % (
+      FIXED_SALT, sparse_image_path, verity_image_path)
   print cmd
   status, output = commands.getstatusoutput(cmd)
   if status:
@@ -92,14 +93,10 @@
 
 def BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
                         block_device, signer_path, key):
-  cmd = ("system/extras/verity/build_verity_metadata.py %s %s %s %s %s %s %s" %
-              (image_size,
-              verity_metadata_path,
-              root_hash,
-              salt,
-              block_device,
-              signer_path,
-              key))
+  cmd_template = (
+      "system/extras/verity/build_verity_metadata.py %s %s %s %s %s %s %s")
+  cmd = cmd_template % (image_size, verity_metadata_path, root_hash, salt,
+                        block_device, signer_path, key)
   print cmd
   status, output = commands.getstatusoutput(cmd)
   if status:
@@ -125,10 +122,13 @@
     return False
   return True
 
-def BuildVerifiedImage(data_image_path, verity_image_path, verity_metadata_path):
-  if not Append2Simg(data_image_path, verity_metadata_path, "Could not append verity metadata!"):
+def BuildVerifiedImage(data_image_path, verity_image_path,
+                       verity_metadata_path):
+  if not Append2Simg(data_image_path, verity_metadata_path,
+                     "Could not append verity metadata!"):
     return False
-  if not Append2Simg(data_image_path, verity_image_path, "Could not append verity tree!"):
+  if not Append2Simg(data_image_path, verity_image_path,
+                     "Could not append verity tree!"):
     return False
   return True
 
@@ -153,7 +153,8 @@
 
   Args:
     out_file: the location to write the verifiable image at
-    prop_dict: a dictionary of properties required for image creation and verification
+    prop_dict: a dictionary of properties required for image creation and
+               verification
   Returns:
     True on success, False otherwise.
   """
@@ -178,13 +179,8 @@
   # build the metadata blocks
   root_hash = prop_dict["verity_root_hash"]
   salt = prop_dict["verity_salt"]
-  if not BuildVerityMetadata(image_size,
-                              verity_metadata_path,
-                              root_hash,
-                              salt,
-                              block_dev,
-                              signer_path,
-                              signer_key):
+  if not BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
+                             block_dev, signer_path, signer_key):
     shutil.rmtree(tempdir_name, ignore_errors=True)
     return False
 
@@ -223,7 +219,8 @@
 
   is_verity_partition = "verity_block_device" in prop_dict
   verity_supported = prop_dict.get("verity") == "true"
-  # adjust the partition size to make room for the hashes if this is to be verified
+  # adjust the partition size to make room for the hashes if this is to be
+  # verified
   if verity_supported and is_verity_partition:
     partition_size = int(prop_dict.get("partition_size"))
     adjusted_size = AdjustPartitionSizeForVerity(partition_size)
@@ -329,7 +326,8 @@
   d["mount_point"] = mount_point
   if mount_point == "system":
     copy_prop("fs_type", "fs_type")
-    # Copy the generic sysetem fs type first, override with specific one if available.
+    # Copy the generic sysetem fs type first, override with specific one if
+    # available.
     copy_prop("system_fs_type", "fs_type")
     copy_prop("system_size", "partition_size")
     copy_prop("system_journal_size", "journal_size")
@@ -397,7 +395,8 @@
 
   image_properties = ImagePropFromGlobalDict(glob_dict, mount_point)
   if not BuildImage(in_dir, image_properties, out_file):
-    print >> sys.stderr, "error: failed to build %s from %s" % (out_file, in_dir)
+    print >> sys.stderr, "error: failed to build %s from %s" % (out_file,
+                                                                in_dir)
     exit(1)
 
 
diff --git a/tools/releasetools/check_target_files_signatures b/tools/releasetools/check_target_files_signatures
new file mode 120000
index 0000000..9f62aa3
--- /dev/null
+++ b/tools/releasetools/check_target_files_signatures
@@ -0,0 +1 @@
+check_target_files_signatures.py
\ No newline at end of file
diff --git a/tools/releasetools/check_target_files_signatures b/tools/releasetools/check_target_files_signatures.py
similarity index 96%
rename from tools/releasetools/check_target_files_signatures
rename to tools/releasetools/check_target_files_signatures.py
index b2f46c1..dd57033 100755
--- a/tools/releasetools/check_target_files_signatures
+++ b/tools/releasetools/check_target_files_signatures.py
@@ -49,14 +49,8 @@
 import re
 import shutil
 import subprocess
-import tempfile
 import zipfile
 
-try:
-  from hashlib import sha1 as sha1
-except ImportError:
-  from sha import sha as sha1
-
 import common
 
 # Work around a bug in python's zipfile module that prevents opening
@@ -127,7 +121,7 @@
   def FindLocalCerts(self):
     to_load = []
     for top in OPTIONS.local_cert_dirs:
-      for dirpath, dirnames, filenames in os.walk(top):
+      for dirpath, _, filenames in os.walk(top):
         certs = [os.path.join(dirpath, i)
                  for i in filenames if i.endswith(".x509.pem")]
         if certs:
@@ -172,6 +166,10 @@
 class APK(object):
   def __init__(self, full_filename, filename):
     self.filename = filename
+    self.certs = None
+    self.shared_uid = None
+    self.package = None
+
     Push(filename+":")
     try:
       self.RecordCerts(full_filename)
@@ -212,7 +210,7 @@
 
     for line in manifest.split("\n"):
       line = line.strip()
-      m = re.search('A: (\S*?)(?:\(0x[0-9a-f]+\))?="(.*?)" \(Raw', line)
+      m = re.search(r'A: (\S*?)(?:\(0x[0-9a-f]+\))?="(.*?)" \(Raw', line)
       if m:
         name = m.group(1)
         if name == "android:sharedUserId":
@@ -232,13 +230,16 @@
   def __init__(self):
     self.max_pkg_len = 30
     self.max_fn_len = 20
+    self.apks = None
+    self.apks_by_basename = None
+    self.certmap = None
 
   def LoadZipFile(self, filename):
     d, z = common.UnzipTemp(filename, '*.apk')
     try:
       self.apks = {}
       self.apks_by_basename = {}
-      for dirpath, dirnames, filenames in os.walk(d):
+      for dirpath, _, filenames in os.walk(d):
         for fn in filenames:
           if fn.endswith(".apk"):
             fullname = os.path.join(dirpath, fn)
@@ -323,8 +324,8 @@
     """Look for instances where a given package that exists in both
     self and other have different certs."""
 
-    all = set(self.apks.keys())
-    all.update(other.apks.keys())
+    all_apks = set(self.apks.keys())
+    all_apks.update(other.apks.keys())
 
     max_pkg_len = max(self.max_pkg_len, other.max_pkg_len)
 
@@ -434,7 +435,7 @@
   try:
     r = main(sys.argv[1:])
     sys.exit(r)
-  except common.ExternalError, e:
+  except common.ExternalError as e:
     print
     print "   ERROR: %s" % (e,)
     print
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 6903dc66..63e438a 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -30,44 +30,45 @@
 import zipfile
 
 import blockimgdiff
-from rangelib import *
+import rangelib
 
 try:
   from hashlib import sha1 as sha1
 except ImportError:
   from sha import sha as sha1
 
-# missing in Python 2.4 and before
-if not hasattr(os, "SEEK_SET"):
-  os.SEEK_SET = 0
 
-class Options(object): pass
-OPTIONS = Options()
-
-DEFAULT_SEARCH_PATH_BY_PLATFORM = {
-    "linux2": "out/host/linux-x86",
-    "darwin": "out/host/darwin-x86",
+class Options(object):
+  def __init__(self):
+    platform_search_path = {
+        "linux2": "out/host/linux-x86",
+        "darwin": "out/host/darwin-x86",
     }
-OPTIONS.search_path = DEFAULT_SEARCH_PATH_BY_PLATFORM.get(sys.platform, None)
 
-OPTIONS.signapk_path = "framework/signapk.jar"  # Relative to search_path
-OPTIONS.extra_signapk_args = []
-OPTIONS.java_path = "java"  # Use the one on the path by default.
-OPTIONS.java_args = "-Xmx2048m" # JVM Args
-OPTIONS.public_key_suffix = ".x509.pem"
-OPTIONS.private_key_suffix = ".pk8"
-OPTIONS.verbose = False
-OPTIONS.tempfiles = []
-OPTIONS.device_specific = None
-OPTIONS.extras = {}
-OPTIONS.info_dict = None
+    self.search_path = platform_search_path.get(sys.platform, None)
+    self.signapk_path = "framework/signapk.jar"  # Relative to search_path
+    self.extra_signapk_args = []
+    self.java_path = "java"  # Use the one on the path by default.
+    self.java_args = "-Xmx2048m" # JVM Args
+    self.public_key_suffix = ".x509.pem"
+    self.private_key_suffix = ".pk8"
+    self.verbose = False
+    self.tempfiles = []
+    self.device_specific = None
+    self.extras = {}
+    self.info_dict = None
+    self.worker_threads = None
+
+
+OPTIONS = Options()
 
 
 # Values for "certificate" in apkcerts that mean special things.
 SPECIAL_CERT_STRINGS = ("PRESIGNED", "EXTERNAL")
 
 
-class ExternalError(RuntimeError): pass
+class ExternalError(RuntimeError):
+  pass
 
 
 def Run(args, **kwargs):
@@ -94,19 +95,19 @@
       pass
 
 
-def LoadInfoDict(input):
+def LoadInfoDict(input_file):
   """Read and parse the META/misc_info.txt key/value pairs from the
   input target files and return a dict."""
 
   def read_helper(fn):
-    if isinstance(input, zipfile.ZipFile):
-      return input.read(fn)
+    if isinstance(input_file, zipfile.ZipFile):
+      return input_file.read(fn)
     else:
-      path = os.path.join(input, *fn.split("/"))
+      path = os.path.join(input_file, *fn.split("/"))
       try:
         with open(path) as f:
           return f.read()
-      except IOError, e:
+      except IOError as e:
         if e.errno == errno.ENOENT:
           raise KeyError(fn)
   d = {}
@@ -122,14 +123,16 @@
 
   if "mkyaffs2_extra_flags" not in d:
     try:
-      d["mkyaffs2_extra_flags"] = read_helper("META/mkyaffs2-extra-flags.txt").strip()
+      d["mkyaffs2_extra_flags"] = read_helper(
+          "META/mkyaffs2-extra-flags.txt").strip()
     except KeyError:
       # ok if flags don't exist
       pass
 
   if "recovery_api_version" not in d:
     try:
-      d["recovery_api_version"] = read_helper("META/recovery-api-version.txt").strip()
+      d["recovery_api_version"] = read_helper(
+          "META/recovery-api-version.txt").strip()
     except KeyError:
       raise ValueError("can't find recovery API version in input target-files")
 
@@ -146,9 +149,11 @@
   try:
     data = read_helper("META/imagesizes.txt")
     for line in data.split("\n"):
-      if not line: continue
+      if not line:
+        continue
       name, value = line.split(" ", 1)
-      if not value: continue
+      if not value:
+        continue
       if name == "blocksize":
         d[name] = value
       else:
@@ -186,7 +191,8 @@
   d = {}
   for line in lines:
     line = line.strip()
-    if not line or line.startswith("#"): continue
+    if not line or line.startswith("#"):
+      continue
     if "=" in line:
       name, value = line.split("=", 1)
       d[name] = value
@@ -194,7 +200,12 @@
 
 def LoadRecoveryFSTab(read_helper, fstab_version):
   class Partition(object):
-    pass
+    def __init__(self, mount_point, fs_type, device, length, device2):
+      self.mount_point = mount_point
+      self.fs_type = fs_type
+      self.device = device
+      self.length = length
+      self.device2 = device2
 
   try:
     data = read_helper("RECOVERY/RAMDISK/etc/recovery.fstab")
@@ -206,68 +217,65 @@
     d = {}
     for line in data.split("\n"):
       line = line.strip()
-      if not line or line.startswith("#"): continue
+      if not line or line.startswith("#"):
+        continue
       pieces = line.split()
-      if not (3 <= len(pieces) <= 4):
+      if not 3 <= len(pieces) <= 4:
         raise ValueError("malformed recovery.fstab line: \"%s\"" % (line,))
-
-      p = Partition()
-      p.mount_point = pieces[0]
-      p.fs_type = pieces[1]
-      p.device = pieces[2]
-      p.length = 0
       options = None
       if len(pieces) >= 4:
         if pieces[3].startswith("/"):
-          p.device2 = pieces[3]
+          device2 = pieces[3]
           if len(pieces) >= 5:
             options = pieces[4]
         else:
-          p.device2 = None
+          device2 = None
           options = pieces[3]
       else:
-        p.device2 = None
+        device2 = None
 
+      mount_point = pieces[0]
+      length = 0
       if options:
         options = options.split(",")
         for i in options:
           if i.startswith("length="):
-            p.length = int(i[7:])
+            length = int(i[7:])
           else:
-              print "%s: unknown option \"%s\"" % (p.mount_point, i)
+            print "%s: unknown option \"%s\"" % (mount_point, i)
 
-      d[p.mount_point] = p
+      d[mount_point] = Partition(mount_point=mount_point, fs_type=pieces[1],
+                                 device=pieces[2], length=length,
+                                 device2=device2)
 
   elif fstab_version == 2:
     d = {}
     for line in data.split("\n"):
       line = line.strip()
-      if not line or line.startswith("#"): continue
+      if not line or line.startswith("#"):
+        continue
       pieces = line.split()
       if len(pieces) != 5:
         raise ValueError("malformed recovery.fstab line: \"%s\"" % (line,))
 
       # Ignore entries that are managed by vold
       options = pieces[4]
-      if "voldmanaged=" in options: continue
+      if "voldmanaged=" in options:
+        continue
 
       # It's a good line, parse it
-      p = Partition()
-      p.device = pieces[0]
-      p.mount_point = pieces[1]
-      p.fs_type = pieces[2]
-      p.device2 = None
-      p.length = 0
-
+      length = 0
       options = options.split(",")
       for i in options:
         if i.startswith("length="):
-          p.length = int(i[7:])
+          length = int(i[7:])
         else:
           # Ignore all unknown options in the unified fstab
           continue
 
-      d[p.mount_point] = p
+      mount_point = pieces[1]
+      d[mount_point] = Partition(mount_point=mount_point, fs_type=pieces[2],
+                                 device=pieces[0], length=length, device2=None)
 
   else:
     raise ValueError("Unknown fstab_version: \"%d\"" % (fstab_version,))
@@ -279,6 +287,7 @@
   for k, v in sorted(d.items()):
     print "%-25s = (%s) %s" % (k, type(v).__name__, v)
 
+
 def BuildBootableImage(sourcedir, fs_config_file, info_dict=None):
   """Take a kernel, cmdline, and ramdisk directory from the input (in
   'sourcedir'), and turn them into a boot image.  Return the image
@@ -305,8 +314,8 @@
 
   p2.wait()
   p1.wait()
-  assert p1.returncode == 0, "mkbootfs of %s ramdisk failed" % (targetname,)
-  assert p2.returncode == 0, "minigzip of %s ramdisk failed" % (targetname,)
+  assert p1.returncode == 0, "mkbootfs of %s ramdisk failed" % (sourcedir,)
+  assert p2.returncode == 0, "minigzip of %s ramdisk failed" % (sourcedir,)
 
   # use MKBOOTIMG from environ, or "mkbootimg" if empty or not set
   mkbootimg = os.getenv('MKBOOTIMG') or "mkbootimg"
@@ -347,7 +356,8 @@
 
   if info_dict.get("verity_key", None):
     path = "/" + os.path.basename(sourcedir).lower()
-    cmd = ["boot_signer", path, img.name, info_dict["verity_key"] + ".pk8", info_dict["verity_key"] + ".x509.pem", img.name]
+    cmd = ["boot_signer", path, img.name, info_dict["verity_key"] + ".pk8",
+           info_dict["verity_key"] + ".x509.pem", img.name]
     p = Run(cmd, stdout=subprocess.PIPE)
     p.communicate()
     assert p.returncode == 0, "boot_signer of %s image failed" % path
@@ -453,7 +463,7 @@
               stdin=devnull.fileno(),
               stdout=devnull.fileno(),
               stderr=subprocess.PIPE)
-      stdout, stderr = p.communicate()
+      _, stderr = p.communicate()
       if p.returncode == 0:
         # Encrypted key with empty string as password.
         key_passwords[k] = ''
@@ -524,20 +534,23 @@
   any, for the given target.  Raise exception if the data is too big.
   Print a warning if the data is nearing the maximum size."""
 
-  if target.endswith(".img"): target = target[:-4]
+  if target.endswith(".img"):
+    target = target[:-4]
   mount_point = "/" + target
 
   fs_type = None
   limit = None
   if info_dict["fstab"]:
-    if mount_point == "/userdata": mount_point = "/data"
+    if mount_point == "/userdata":
+      mount_point = "/data"
     p = info_dict["fstab"][mount_point]
     fs_type = p.fs_type
     device = p.device
     if "/" in device:
       device = device[device.rfind("/")+1:]
     limit = info_dict.get(device + "_size", None)
-  if not fs_type or not limit: return
+  if not fs_type or not limit:
+    return
 
   if fs_type == "yaffs2":
     # image size should be increased by 1/64th to account for the
@@ -562,7 +575,8 @@
   certmap = {}
   for line in tf_zip.read("META/apkcerts.txt").split("\n"):
     line = line.strip()
-    if not line: continue
+    if not line:
+      continue
     m = re.match(r'^name="(.*)"\s+certificate="(.*)"\s+'
                  r'private_key="(.*)"$', line)
     if m:
@@ -622,13 +636,11 @@
          "java_path=", "java_args=", "public_key_suffix=",
          "private_key_suffix=", "device_specific=", "extra="] +
         list(extra_long_opts))
-  except getopt.GetoptError, err:
+  except getopt.GetoptError as err:
     Usage(docstring)
     print "**", str(err), "**"
     sys.exit(2)
 
-  path_specified = False
-
   for o, a in opts:
     if o in ("-h", "--help"):
       Usage(docstring)
@@ -707,7 +719,8 @@
         if i not in current or not current[i]:
           missing.append(i)
       # Are all the passwords already in the file?
-      if not missing: return current
+      if not missing:
+        return current
 
       for i in missing:
         current[i] = ""
@@ -721,7 +734,7 @@
 
       current = self.UpdateAndReadFile(current)
 
-  def PromptResult(self, current):
+  def PromptResult(self, current): # pylint: disable=no-self-use
     """Prompt the user to enter a value (password) for each key in
     'current' whose value is fales.  Returns a new dict with all the
     values.
@@ -732,9 +745,10 @@
         result[k] = v
       else:
         while True:
-          result[k] = getpass.getpass("Enter password for %s key> "
-                                      % (k,)).strip()
-          if result[k]: break
+          result[k] = getpass.getpass(
+              "Enter password for %s key> " % k).strip()
+          if result[k]:
+            break
     return result
 
   def UpdateAndReadFile(self, current):
@@ -742,14 +756,13 @@
       return self.PromptResult(current)
 
     f = open(self.pwfile, "w")
-    os.chmod(self.pwfile, 0600)
+    os.chmod(self.pwfile, 0o600)
     f.write("# Enter key passwords between the [[[ ]]] brackets.\n")
     f.write("# (Additional spaces are harmless.)\n\n")
 
     first_line = None
-    sorted = [(not v, k, v) for (k, v) in current.iteritems()]
-    sorted.sort()
-    for i, (_, k, v) in enumerate(sorted):
+    sorted_list = sorted([(not v, k, v) for (k, v) in current.iteritems()])
+    for i, (_, k, v) in enumerate(sorted_list):
       f.write("[[[  %s  ]]] %s\n" % (v, k))
       if not v and first_line is None:
         # position cursor on first line with no password.
@@ -763,19 +776,21 @@
 
   def ReadFile(self):
     result = {}
-    if self.pwfile is None: return result
+    if self.pwfile is None:
+      return result
     try:
       f = open(self.pwfile, "r")
       for line in f:
         line = line.strip()
-        if not line or line[0] == '#': continue
+        if not line or line[0] == '#':
+          continue
         m = re.match(r"^\[\[\[\s*(.*?)\s*\]\]\]\s*(\S+)$", line)
         if not m:
           print "failed to parse password file: ", line
         else:
           result[m.group(2)] = m.group(1)
       f.close()
-    except IOError, e:
+    except IOError as e:
       if e.errno != errno.ENOENT:
         print "error reading password file: ", str(e)
     return result
@@ -821,16 +836,16 @@
     zipfile.ZIP64_LIMIT = saved_zip64_limit
 
 
-def ZipWriteStr(zip, filename, data, perms=0644, compression=None):
+def ZipWriteStr(zip_file, filename, data, perms=0o644, compression=None):
   # use a fixed timestamp so the output is repeatable.
   zinfo = zipfile.ZipInfo(filename=filename,
                           date_time=(2009, 1, 1, 0, 0, 0))
   if compression is None:
-    zinfo.compress_type = zip.compression
+    zinfo.compress_type = zip_file.compression
   else:
     zinfo.compress_type = compression
   zinfo.external_attr = perms << 16
-  zip.writestr(zinfo, data)
+  zip_file.writestr(zinfo, data)
 
 
 class DeviceSpecificParams(object):
@@ -845,7 +860,8 @@
 
     if self.module is None:
       path = OPTIONS.device_specific
-      if not path: return
+      if not path:
+        return
       try:
         if os.path.isdir(path):
           info = imp.find_module("releasetools", [path])
@@ -983,7 +999,8 @@
       err = []
       def run():
         _, e = p.communicate()
-        if e: err.append(e)
+        if e:
+          err.append(e)
       th = threading.Thread(target=run)
       th.start()
       th.join(timeout=300)   # 5 mins
@@ -1050,7 +1067,7 @@
           print "%8.2f sec %8d / %8d bytes (%6.2f%%) %s" % (
               dur, len(patch), tf.size, 100.0 * len(patch) / tf.size, name)
       lock.release()
-    except Exception, e:
+    except Exception as e:
       print e
       raise
 
@@ -1063,8 +1080,9 @@
     threads.pop().join()
 
 
-class BlockDifference:
-  def __init__(self, partition, tgt, src=None, check_first_block=False, version=None):
+class BlockDifference(object):
+  def __init__(self, partition, tgt, src=None, check_first_block=False,
+               version=None):
     self.tgt = tgt
     self.src = src
     self.partition = partition
@@ -1094,7 +1112,8 @@
     else:
       script.Print("Patching %s image after verification." % (self.partition,))
 
-    if progress: script.ShowProgress(progress, 0)
+    if progress:
+      script.ShowProgress(progress, 0)
     self._WriteUpdate(script, output_zip)
 
   def WriteVerifyScript(self, script):
@@ -1108,11 +1127,11 @@
                             '"%s.new.dat", "%s.patch.dat") then') %
                            (self.device, partition, partition, partition))
       else:
-        script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' %
-                            (self.device, self.src.care_map.to_string_raw(),
-                            self.src.TotalSha1()))
+        script.AppendExtra('if range_sha1("%s", "%s") == "%s" then' % (
+            self.device, self.src.care_map.to_string_raw(),
+            self.src.TotalSha1()))
       script.Print('Verified %s image...' % (partition,))
-      script.AppendExtra('else');
+      script.AppendExtra('else')
 
       # When generating incrementals for the system and vendor partitions,
       # explicitly check the first block (which contains the superblock) of
@@ -1147,9 +1166,9 @@
             'package_extract_file("{partition}.transfer.list"), '
             '"{partition}.new.dat", "{partition}.patch.dat");\n'.format(
                 device=self.device, partition=self.partition))
-    script.AppendExtra(script._WordWrap(call))
+    script.AppendExtra(script.WordWrap(call))
 
-  def _HashBlocks(self, source, ranges):
+  def _HashBlocks(self, source, ranges): # pylint: disable=no-self-use
     data = source.ReadRangeSet(ranges)
     ctx = sha1()
 
@@ -1159,8 +1178,8 @@
     return ctx.hexdigest()
 
   def _CheckFirstBlock(self, script):
-    r = RangeSet((0, 1))
-    srchash = self._HashBlocks(self.src, r);
+    r = rangelib.RangeSet((0, 1))
+    srchash = self._HashBlocks(self.src, r)
 
     script.AppendExtra(('(range_sha1("%s", "%s") == "%s") || '
                         'abort("%s has been remounted R/W; '
@@ -1172,16 +1191,21 @@
 
 
 # map recovery.fstab's fs_types to mount/format "partition types"
-PARTITION_TYPES = { "yaffs2": "MTD", "mtd": "MTD",
-                    "ext4": "EMMC", "emmc": "EMMC",
-                    "f2fs": "EMMC" }
+PARTITION_TYPES = {
+    "yaffs2": "MTD",
+    "mtd": "MTD",
+    "ext4": "EMMC",
+    "emmc": "EMMC",
+    "f2fs": "EMMC"
+}
 
 def GetTypeAndDevice(mount_point, info):
   fstab = info["fstab"]
   if fstab:
-    return PARTITION_TYPES[fstab[mount_point].fs_type], fstab[mount_point].device
+    return (PARTITION_TYPES[fstab[mount_point].fs_type],
+            fstab[mount_point].device)
   else:
-    return None
+    raise KeyError
 
 
 def ParseCertificate(data):
@@ -1243,16 +1267,15 @@
 else
   log -t recovery "Recovery image already installed"
 fi
-""" % { 'boot_size': boot_img.size,
-        'boot_sha1': boot_img.sha1,
-        'recovery_size': recovery_img.size,
-        'recovery_sha1': recovery_img.sha1,
-        'boot_type': boot_type,
-        'boot_device': boot_device,
-        'recovery_type': recovery_type,
-        'recovery_device': recovery_device,
-        'bonus_args': bonus_args,
-        }
+""" % {'boot_size': boot_img.size,
+       'boot_sha1': boot_img.sha1,
+       'recovery_size': recovery_img.size,
+       'recovery_sha1': recovery_img.sha1,
+       'boot_type': boot_type,
+       'boot_device': boot_device,
+       'recovery_type': recovery_type,
+       'recovery_device': recovery_device,
+       'bonus_args': bonus_args}
 
   # The install script location moved from /system/etc to /system/bin
   # in the L release.  Parse the init.rc file to find out where the
@@ -1261,12 +1284,12 @@
   try:
     with open(os.path.join(input_dir, "BOOT", "RAMDISK", "init.rc")) as f:
       for line in f:
-        m = re.match("^service flash_recovery /system/(\S+)\s*$", line)
+        m = re.match(r"^service flash_recovery /system/(\S+)\s*$", line)
         if m:
           sh_location = m.group(1)
           print "putting script in", sh_location
           break
-  except (OSError, IOError), e:
+  except (OSError, IOError) as e:
     print "failed to read init.rc: %s" % (e,)
 
   output_sink(sh_location, sh)
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
index 934d751..3d0da88 100644
--- a/tools/releasetools/edify_generator.py
+++ b/tools/releasetools/edify_generator.py
@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import os
 import re
 
 import common
@@ -36,7 +35,7 @@
     return x
 
   @staticmethod
-  def _WordWrap(cmd, linelen=80):
+  def WordWrap(cmd, linelen=80):
     """'cmd' should be a function call with null characters after each
     parameter (eg, "somefun(foo,\0bar,\0baz)").  This function wraps cmd
     to a given line length, replacing nulls with spaces and/or newlines
@@ -77,32 +76,30 @@
     cmd = ('file_getprop("/oem/oem.prop", "{name}") == "{value}" || '
            'abort("This package expects the value \\"{value}\\" for '
            '\\"{name}\\" on the OEM partition; this has value \\"" + '
-           'file_getprop("/oem/oem.prop", "{name}") + "\\".");'
-           ).format(name=name, value=value)
+           'file_getprop("/oem/oem.prop", "{name}") + "\\".");').format(
+               name=name, value=value)
     self.script.append(cmd)
 
   def AssertSomeFingerprint(self, *fp):
     """Assert that the current recovery build fingerprint is one of *fp."""
     if not fp:
       raise ValueError("must specify some fingerprints")
-    cmd = (
-           ' ||\n    '.join([('getprop("ro.build.fingerprint") == "%s"')
-                        % i for i in fp]) +
+    cmd = (' ||\n    '.join([('getprop("ro.build.fingerprint") == "%s"') % i
+                             for i in fp]) +
            ' ||\n    abort("Package expects build fingerprint of %s; this '
-           'device has " + getprop("ro.build.fingerprint") + ".");'
-           ) % (" or ".join(fp),)
+           'device has " + getprop("ro.build.fingerprint") + ".");') % (
+               " or ".join(fp))
     self.script.append(cmd)
 
   def AssertSomeThumbprint(self, *fp):
     """Assert that the current recovery build thumbprint is one of *fp."""
     if not fp:
       raise ValueError("must specify some thumbprints")
-    cmd = (
-           ' ||\n    '.join([('getprop("ro.build.thumbprint") == "%s"')
-                        % i for i in fp]) +
+    cmd = (' ||\n    '.join([('getprop("ro.build.thumbprint") == "%s"') % i
+                             for i in fp]) +
            ' ||\n    abort("Package expects build thumbprint of %s; this '
-           'device has " + getprop("ro.build.thumbprint") + ".");'
-           ) % (" or ".join(fp),)
+           'device has " + getprop("ro.build.thumbprint") + ".");') % (
+               " or ".join(fp))
     self.script.append(cmd)
 
   def AssertOlderBuild(self, timestamp, timestamp_text):
@@ -111,15 +108,15 @@
     self.script.append(
         ('(!less_than_int(%s, getprop("ro.build.date.utc"))) || '
          'abort("Can\'t install this package (%s) over newer '
-         'build (" + getprop("ro.build.date") + ").");'
-         ) % (timestamp, timestamp_text))
+         'build (" + getprop("ro.build.date") + ").");') % (timestamp,
+                                                            timestamp_text))
 
   def AssertDevice(self, device):
     """Assert that the device identifier is the given string."""
     cmd = ('getprop("ro.product.device") == "%s" || '
            'abort("This package is for \\"%s\\" devices; '
-           'this is a \\"" + getprop("ro.product.device") + "\\".");'
-           ) % (device, device)
+           'this is a \\"" + getprop("ro.product.device") + "\\".");') % (
+               device, device)
     self.script.append(cmd)
 
   def AssertSomeBootloader(self, *bootloaders):
@@ -128,7 +125,7 @@
            " ||\0".join(['getprop("ro.bootloader") == "%s"' % (b,)
                          for b in bootloaders]) +
            ");")
-    self.script.append(self._WordWrap(cmd))
+    self.script.append(self.WordWrap(cmd))
 
   def ShowProgress(self, frac, dur):
     """Update the progress bar, advancing it over 'frac' over the next
@@ -180,9 +177,9 @@
           if "=" in option:
             key, value = option.split("=", 1)
             mount_dict[key] = value
-      self.script.append('mount("%s", "%s", "%s", "%s", "%s");' %
-                         (p.fs_type, common.PARTITION_TYPES[p.fs_type],
-                          p.device, p.mount_point, mount_dict.get(p.fs_type, "")))
+      self.script.append('mount("%s", "%s", "%s", "%s", "%s");' % (
+          p.fs_type, common.PARTITION_TYPES[p.fs_type], p.device,
+          p.mount_point, mount_dict.get(p.fs_type, "")))
       self.mounts.add(p.mount_point)
 
   def UnpackPackageDir(self, src, dst):
@@ -205,18 +202,17 @@
     fstab = self.info.get("fstab", None)
     if fstab:
       p = fstab[partition]
-      if (p.fs_type not in ( "ext2", "ext3", "ext4")):
+      if p.fs_type not in ("ext2", "ext3", "ext4"):
         raise ValueError("Partition %s cannot be tuned\n" % (partition,))
-    self.script.append('tune2fs(' +
-                       "".join(['"%s", ' % (i,) for i in options]) +
-                       '"%s") || abort("Failed to tune partition %s");'
-                       % ( p.device,partition));
+    self.script.append(
+        'tune2fs(' + "".join(['"%s", ' % (i,) for i in options]) +
+        '"%s") || abort("Failed to tune partition %s");' % (
+            p.device, partition))
 
   def FormatPartition(self, partition):
     """Format the given partition, specified by its mount point (eg,
     "/system")."""
 
-    reserve_size = 0
     fstab = self.info.get("fstab", None)
     if fstab:
       p = fstab[partition]
@@ -235,9 +231,10 @@
 
   def DeleteFiles(self, file_list):
     """Delete all files in file_list."""
-    if not file_list: return
+    if not file_list:
+      return
     cmd = "delete(" + ",\0".join(['"%s"' % (i,) for i in file_list]) + ");"
-    self.script.append(self._WordWrap(cmd))
+    self.script.append(self.WordWrap(cmd))
 
   def RenameFile(self, srcfile, tgtfile):
     """Moves a file from one location to another."""
@@ -251,7 +248,7 @@
        skip the action if the file exists.  Used when a patch
        is later renamed."""
     cmd = ('sha1_check(read_file("%s"), %s) || ' % (tgtfile, tgtsha1))
-    self.script.append(self._WordWrap(cmd))
+    self.script.append(self.WordWrap(cmd))
 
   def ApplyPatch(self, srcfile, tgtfile, tgtsize, tgtsha1, *patchpairs):
     """Apply binary patches (in *patchpairs) to the given srcfile to
@@ -265,7 +262,7 @@
       cmd.append(',\0%s, package_extract_file("%s")' % patchpairs[i:i+2])
     cmd.append(');')
     cmd = "".join(cmd)
-    self.script.append(self._WordWrap(cmd))
+    self.script.append(self.WordWrap(cmd))
 
   def WriteRawImage(self, mount_point, fn, mapfn=None):
     """Write the given package file into the partition for the given
@@ -289,33 +286,37 @@
           self.script.append(
               'package_extract_file("%(fn)s", "%(device)s");' % args)
       else:
-        raise ValueError("don't know how to write \"%s\" partitions" % (p.fs_type,))
+        raise ValueError(
+            "don't know how to write \"%s\" partitions" % p.fs_type)
 
   def SetPermissions(self, fn, uid, gid, mode, selabel, capabilities):
     """Set file ownership and permissions."""
     if not self.info.get("use_set_metadata", False):
       self.script.append('set_perm(%d, %d, 0%o, "%s");' % (uid, gid, mode, fn))
     else:
-      if capabilities is None: capabilities = "0x0"
+      if capabilities is None:
+        capabilities = "0x0"
       cmd = 'set_metadata("%s", "uid", %d, "gid", %d, "mode", 0%o, ' \
           '"capabilities", %s' % (fn, uid, gid, mode, capabilities)
       if selabel is not None:
-        cmd += ', "selabel", "%s"' % ( selabel )
+        cmd += ', "selabel", "%s"' % selabel
       cmd += ');'
       self.script.append(cmd)
 
-  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode, selabel, capabilities):
+  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode, selabel,
+                              capabilities):
     """Recursively set path ownership and permissions."""
     if not self.info.get("use_set_metadata", False):
       self.script.append('set_perm_recursive(%d, %d, 0%o, 0%o, "%s");'
                          % (uid, gid, dmode, fmode, fn))
     else:
-      if capabilities is None: capabilities = "0x0"
+      if capabilities is None:
+        capabilities = "0x0"
       cmd = 'set_metadata_recursive("%s", "uid", %d, "gid", %d, ' \
           '"dmode", 0%o, "fmode", 0%o, "capabilities", %s' \
           % (fn, uid, gid, dmode, fmode, capabilities)
       if selabel is not None:
-        cmd += ', "selabel", "%s"' % ( selabel )
+        cmd += ', "selabel", "%s"' % selabel
       cmd += ');'
       self.script.append(cmd)
 
@@ -328,15 +329,15 @@
     for dest, links in sorted(by_dest.iteritems()):
       cmd = ('symlink("%s", ' % (dest,) +
              ",\0".join(['"' + i + '"' for i in sorted(links)]) + ");")
-      self.script.append(self._WordWrap(cmd))
+      self.script.append(self.WordWrap(cmd))
 
   def AppendExtra(self, extra):
     """Append text verbatim to the output script."""
     self.script.append(extra)
 
   def Unmount(self, mount_point):
-    self.script.append('unmount("%s");' % (mount_point,))
-    self.mounts.remove(mount_point);
+    self.script.append('unmount("%s");' % mount_point)
+    self.mounts.remove(mount_point)
 
   def UnmountAll(self):
     for p in sorted(self.mounts):
@@ -359,4 +360,4 @@
     else:
       data = open(input_path, "rb").read()
     common.ZipWriteStr(output_zip, "META-INF/com/google/android/update-binary",
-                       data, perms=0755)
+                       data, perms=0o755)
diff --git a/tools/releasetools/img_from_target_files.py b/tools/releasetools/img_from_target_files.py
index 4dda0b7..8c5acd8 100755
--- a/tools/releasetools/img_from_target_files.py
+++ b/tools/releasetools/img_from_target_files.py
@@ -32,18 +32,10 @@
   print >> sys.stderr, "Python 2.7 or newer is required."
   sys.exit(1)
 
-import errno
 import os
-import re
 import shutil
-import subprocess
-import tempfile
 import zipfile
 
-# missing in Python 2.4 and before
-if not hasattr(os, "SEEK_SET"):
-  os.SEEK_SET = 0
-
 import common
 
 OPTIONS = common.OPTIONS
@@ -58,7 +50,7 @@
 def main(argv):
   bootable_only = [False]
 
-  def option_handler(o, a):
+  def option_handler(o, _):
     if o in ("-z", "--bootable_zip"):
       bootable_only[0] = True
     else:
@@ -116,7 +108,7 @@
       boot_image = common.GetBootableImage(
           "boot.img", "boot.img", OPTIONS.input_tmp, "BOOT")
       if boot_image:
-          boot_image.AddToZip(output_zip)
+        boot_image.AddToZip(output_zip)
       recovery_image = common.GetBootableImage(
           "recovery.img", "recovery.img", OPTIONS.input_tmp, "RECOVERY")
       if recovery_image:
@@ -157,7 +149,7 @@
   try:
     common.CloseInheritedPipes()
     main(sys.argv[1:])
-  except common.ExternalError, e:
+  except common.ExternalError as e:
     print
     print "   ERROR: %s" % (e,)
     print
diff --git a/tools/releasetools/make_recovery_patch b/tools/releasetools/make_recovery_patch
new file mode 120000
index 0000000..45cec08
--- /dev/null
+++ b/tools/releasetools/make_recovery_patch
@@ -0,0 +1 @@
+make_recovery_patch.py
\ No newline at end of file
diff --git a/tools/releasetools/make_recovery_patch b/tools/releasetools/make_recovery_patch.py
similarity index 100%
rename from tools/releasetools/make_recovery_patch
rename to tools/releasetools/make_recovery_patch.py
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
new file mode 120000
index 0000000..6755a90
--- /dev/null
+++ b/tools/releasetools/ota_from_target_files
@@ -0,0 +1 @@
+ota_from_target_files.py
\ No newline at end of file
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files.py
similarity index 86%
rename from tools/releasetools/ota_from_target_files
rename to tools/releasetools/ota_from_target_files.py
index b71baf9..26fbaf0 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files.py
@@ -88,21 +88,13 @@
   sys.exit(1)
 
 import copy
-import errno
 import multiprocessing
 import os
-import re
-import subprocess
 import tempfile
-import time
 import zipfile
 
-from hashlib import sha1 as sha1
-
 import common
 import edify_generator
-import build_image
-import blockimgdiff
 import sparse_img
 
 OPTIONS = common.OPTIONS
@@ -130,7 +122,8 @@
   """Given a dict, return the key corresponding to the largest
   value.  Returns 'default' if the dict is empty."""
   x = [(v, k) for (k, v) in d.iteritems()]
-  if not x: return default
+  if not x:
+    return default
   x.sort()
   return x[-1][1]
 
@@ -138,12 +131,12 @@
 def IsSymlink(info):
   """Return true if the zipfile.ZipInfo object passed in represents a
   symlink."""
-  return (info.external_attr >> 16) == 0120777
+  return (info.external_attr >> 16) == 0o120777
 
 def IsRegular(info):
   """Return true if the zipfile.ZipInfo object passed in represents a
   symlink."""
-  return (info.external_attr >> 28) == 010
+  return (info.external_attr >> 28) == 0o10
 
 def ClosestFileMatch(src, tgtfiles, existing):
   """Returns the closest file match between a source file and list
@@ -170,15 +163,15 @@
     return result
   return None
 
-class ItemSet:
+class ItemSet(object):
   def __init__(self, partition, fs_config):
     self.partition = partition
     self.fs_config = fs_config
     self.ITEMS = {}
 
-  def Get(self, name, dir=False):
+  def Get(self, name, is_dir=False):
     if name not in self.ITEMS:
-      self.ITEMS[name] = Item(self, name, dir=dir)
+      self.ITEMS[name] = Item(self, name, is_dir=is_dir)
     return self.ITEMS[name]
 
   def GetMetadata(self, input_zip):
@@ -187,7 +180,8 @@
     output = input_zip.read(self.fs_config)
 
     for line in output.split("\n"):
-      if not line: continue
+      if not line:
+        continue
       columns = line.split()
       name, uid, gid, mode = columns[:4]
       selabel = None
@@ -209,20 +203,22 @@
         i.mode = int(mode, 8)
         i.selabel = selabel
         i.capabilities = capabilities
-        if i.dir:
+        if i.is_dir:
           i.children.sort(key=lambda i: i.name)
 
     # set metadata for the files generated by this script.
     i = self.ITEMS.get("system/recovery-from-boot.p", None)
-    if i: i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0644, None, None
+    if i:
+      i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0o644, None, None
     i = self.ITEMS.get("system/etc/install-recovery.sh", None)
-    if i: i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0544, None, None
+    if i:
+      i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0o544, None, None
 
 
-class Item:
+class Item(object):
   """Items represent the metadata (user, group, mode) of files and
   directories in the system image."""
-  def __init__(self, itemset, name, dir=False):
+  def __init__(self, itemset, name, is_dir=False):
     self.itemset = itemset
     self.name = name
     self.uid = None
@@ -230,22 +226,26 @@
     self.mode = None
     self.selabel = None
     self.capabilities = None
-    self.dir = dir
+    self.is_dir = is_dir
+    self.descendants = None
+    self.best_subtree = None
 
     if name:
-      self.parent = itemset.Get(os.path.dirname(name), dir=True)
+      self.parent = itemset.Get(os.path.dirname(name), is_dir=True)
       self.parent.children.append(self)
     else:
       self.parent = None
-    if dir:
+    if self.is_dir:
       self.children = []
 
   def Dump(self, indent=0):
     if self.uid is not None:
-      print "%s%s %d %d %o" % ("  "*indent, self.name, self.uid, self.gid, self.mode)
+      print "%s%s %d %d %o" % (
+          "  " * indent, self.name, self.uid, self.gid, self.mode)
     else:
-      print "%s%s %s %s %s" % ("  "*indent, self.name, self.uid, self.gid, self.mode)
-    if self.dir:
+      print "%s%s %s %s %s" % (
+          "  " * indent, self.name, self.uid, self.gid, self.mode)
+    if self.is_dir:
       print "%s%s" % ("  "*indent, self.descendants)
       print "%s%s" % ("  "*indent, self.best_subtree)
       for i in self.children:
@@ -253,21 +253,24 @@
 
   def CountChildMetadata(self):
     """Count up the (uid, gid, mode, selabel, capabilities) tuples for
-    all children and determine the best strategy for using set_perm_recursive and
-    set_perm to correctly chown/chmod all the files to their desired
+    all children and determine the best strategy for using set_perm_recursive
+    and set_perm to correctly chown/chmod all the files to their desired
     values.  Recursively calls itself for all descendants.
 
-    Returns a dict of {(uid, gid, dmode, fmode, selabel, capabilities): count} counting up
-    all descendants of this node.  (dmode or fmode may be None.)  Also
-    sets the best_subtree of each directory Item to the (uid, gid,
-    dmode, fmode, selabel, capabilities) tuple that will match the most
-    descendants of that Item.
+    Returns a dict of {(uid, gid, dmode, fmode, selabel, capabilities): count}
+    counting up all descendants of this node.  (dmode or fmode may be None.)
+    Also sets the best_subtree of each directory Item to the (uid, gid, dmode,
+    fmode, selabel, capabilities) tuple that will match the most descendants of
+    that Item.
     """
 
-    assert self.dir
-    d = self.descendants = {(self.uid, self.gid, self.mode, None, self.selabel, self.capabilities): 1}
+    assert self.is_dir
+    key = (self.uid, self.gid, self.mode, None, self.selabel,
+           self.capabilities)
+    self.descendants = {key: 1}
+    d = self.descendants
     for i in self.children:
-      if i.dir:
+      if i.is_dir:
         for k, v in i.CountChildMetadata().iteritems():
           d[k] = d.get(k, 0) + v
       else:
@@ -286,17 +289,23 @@
 
     # Now find the dmode, fmode, selabel, and capabilities that match
     # the most descendants with that (uid, gid), and choose those.
-    best_dmode = (0, 0755)
-    best_fmode = (0, 0644)
+    best_dmode = (0, 0o755)
+    best_fmode = (0, 0o644)
     best_selabel = (0, None)
     best_capabilities = (0, None)
     for k, count in d.iteritems():
-      if k[:2] != ug: continue
-      if k[2] is not None and count >= best_dmode[0]: best_dmode = (count, k[2])
-      if k[3] is not None and count >= best_fmode[0]: best_fmode = (count, k[3])
-      if k[4] is not None and count >= best_selabel[0]: best_selabel = (count, k[4])
-      if k[5] is not None and count >= best_capabilities[0]: best_capabilities = (count, k[5])
-    self.best_subtree = ug + (best_dmode[1], best_fmode[1], best_selabel[1], best_capabilities[1])
+      if k[:2] != ug:
+        continue
+      if k[2] is not None and count >= best_dmode[0]:
+        best_dmode = (count, k[2])
+      if k[3] is not None and count >= best_fmode[0]:
+        best_fmode = (count, k[3])
+      if k[4] is not None and count >= best_selabel[0]:
+        best_selabel = (count, k[4])
+      if k[5] is not None and count >= best_capabilities[0]:
+        best_capabilities = (count, k[5])
+    self.best_subtree = ug + (
+        best_dmode[1], best_fmode[1], best_selabel[1], best_capabilities[1])
 
     return d
 
@@ -308,11 +317,11 @@
     self.CountChildMetadata()
 
     def recurse(item, current):
-      # current is the (uid, gid, dmode, fmode, selabel, capabilities) tuple that the current
-      # item (and all its children) have already been set to.  We only
-      # need to issue set_perm/set_perm_recursive commands if we're
+      # current is the (uid, gid, dmode, fmode, selabel, capabilities) tuple
+      # that the current item (and all its children) have already been set to.
+      # We only need to issue set_perm/set_perm_recursive commands if we're
       # supposed to be something different.
-      if item.dir:
+      if item.is_dir:
         if current != item.best_subtree:
           script.SetPermissionsRecursive("/"+item.name, *item.best_subtree)
           current = item.best_subtree
@@ -367,9 +376,9 @@
             data = input_zip.read(info.filename)
           output_zip.writestr(info2, data)
         if fn.endswith("/"):
-          itemset.Get(fn[:-1], dir=True)
+          itemset.Get(fn[:-1], is_dir=True)
         else:
-          itemset.Get(fn, dir=False)
+          itemset.Get(fn)
 
   symlinks.sort()
   return symlinks
@@ -383,17 +392,19 @@
                   whole_file=True)
 
 
-def AppendAssertions(script, info_dict, oem_dict = None):
+def AppendAssertions(script, info_dict, oem_dict=None):
   oem_props = info_dict.get("oem_fingerprint_properties")
   if oem_props is None or len(oem_props) == 0:
     device = GetBuildProp("ro.product.device", info_dict)
     script.AssertDevice(device)
   else:
     if oem_dict is None:
-      raise common.ExternalError("No OEM file provided to answer expected assertions")
+      raise common.ExternalError(
+          "No OEM file provided to answer expected assertions")
     for prop in oem_props.split():
       if oem_dict.get(prop) is None:
-        raise common.ExternalError("The OEM file is missing the property %s" % prop)
+        raise common.ExternalError(
+            "The OEM file is missing the property %s" % prop)
       script.AssertOemProperty(prop, oem_dict.get(prop))
 
 
@@ -421,10 +432,10 @@
   if oem_props is None:
     return GetBuildProp("ro.build.fingerprint", info_dict)
   return "%s/%s/%s:%s" % (
-    GetOemProperty("ro.product.brand", oem_props, oem_dict, info_dict),
-    GetOemProperty("ro.product.name", oem_props, oem_dict, info_dict),
-    GetOemProperty("ro.product.device", oem_props, oem_dict, info_dict),
-    GetBuildProp("ro.build.thumbprint", info_dict))
+      GetOemProperty("ro.product.brand", oem_props, oem_dict, info_dict),
+      GetOemProperty("ro.product.name", oem_props, oem_dict, info_dict),
+      GetOemProperty("ro.product.device", oem_props, oem_dict, info_dict),
+      GetBuildProp("ro.build.thumbprint", info_dict))
 
 
 def GetImage(which, tmpdir, info_dict):
@@ -474,15 +485,16 @@
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
     script.Mount("/oem", recovery_mount_options)
-    oem_dict = common.LoadDictionaryFromLines(open(OPTIONS.oem_source).readlines())
+    oem_dict = common.LoadDictionaryFromLines(
+        open(OPTIONS.oem_source).readlines())
 
-  metadata = {"post-build": CalculateFingerprint(
-                               oem_props, oem_dict, OPTIONS.info_dict),
-              "pre-device": GetOemProperty("ro.product.device", oem_props, oem_dict,
+  metadata = {
+      "post-build": CalculateFingerprint(oem_props, oem_dict,
                                          OPTIONS.info_dict),
-              "post-timestamp": GetBuildProp("ro.build.date.utc",
-                                             OPTIONS.info_dict),
-              }
+      "pre-device": GetOemProperty("ro.product.device", oem_props, oem_dict,
+                                   OPTIONS.info_dict),
+      "post-timestamp": GetBuildProp("ro.build.date.utc", OPTIONS.info_dict),
+  }
 
   device_specific = common.DeviceSpecificParams(
       input_zip=input_zip,
@@ -521,7 +533,8 @@
   #    do normal full package installation:
   #       wipe and install system, boot image, etc.
   #       set up system to update recovery partition on first boot
-  #    complete script normally (allow recovery to mark itself finished and reboot)
+  #    complete script normally
+  #    (allow recovery to mark itself finished and reboot)
 
   recovery_img = common.GetBootableImage("recovery.img", "recovery.img",
                                          OPTIONS.input_tmp, "RECOVERY")
@@ -585,7 +598,7 @@
   if not block_based:
     def output_sink(fn, data):
       common.ZipWriteStr(output_zip, "recovery/" + fn, data)
-      system_items.Get("system/" + fn, dir=False)
+      system_items.Get("system/" + fn)
 
     common.MakeRecoveryPatch(OPTIONS.input_tmp, output_sink,
                              recovery_img, boot_img)
@@ -686,7 +699,7 @@
   while len(dirs) > 0:
     path = "/".join(dirs)
     if path in known_paths:
-      break;
+      break
     known_paths.add(path)
     dirs.pop()
 
@@ -701,11 +714,12 @@
   script = edify_generator.EdifyGenerator(source_version,
                                           OPTIONS.target_info_dict)
 
-  metadata = {"pre-device": GetBuildProp("ro.product.device",
-                                         OPTIONS.source_info_dict),
-              "post-timestamp": GetBuildProp("ro.build.date.utc",
-                                             OPTIONS.target_info_dict),
-              }
+  metadata = {
+      "pre-device": GetBuildProp("ro.product.device",
+                                 OPTIONS.source_info_dict),
+      "post-timestamp": GetBuildProp("ro.build.date.utc",
+                                     OPTIONS.target_info_dict),
+  }
 
   device_specific = common.DeviceSpecificParams(
       source_zip=source_zip,
@@ -730,12 +744,8 @@
   updating_boot = (not OPTIONS.two_step and
                    (source_boot.data != target_boot.data))
 
-  source_recovery = common.GetBootableImage(
-      "/tmp/recovery.img", "recovery.img", OPTIONS.source_tmp, "RECOVERY",
-      OPTIONS.source_info_dict)
   target_recovery = common.GetBootableImage(
       "/tmp/recovery.img", "recovery.img", OPTIONS.target_tmp, "RECOVERY")
-  updating_recovery = (source_recovery.data != target_recovery.data)
 
   system_src = GetImage("system", OPTIONS.source_tmp, OPTIONS.source_info_dict)
   system_tgt = GetImage("system", OPTIONS.target_tmp, OPTIONS.target_info_dict)
@@ -753,8 +763,10 @@
   if HasVendorPartition(target_zip):
     if not HasVendorPartition(source_zip):
       raise RuntimeError("can't generate incremental that adds /vendor")
-    vendor_src = GetImage("vendor", OPTIONS.source_tmp, OPTIONS.source_info_dict)
-    vendor_tgt = GetImage("vendor", OPTIONS.target_tmp, OPTIONS.target_info_dict)
+    vendor_src = GetImage("vendor", OPTIONS.source_tmp,
+                          OPTIONS.source_info_dict)
+    vendor_tgt = GetImage("vendor", OPTIONS.target_tmp,
+                          OPTIONS.target_info_dict)
     vendor_diff = common.BlockDifference("vendor", vendor_tgt, vendor_src,
                                          check_first_block=True,
                                          version=blockimgdiff_version)
@@ -762,13 +774,15 @@
     vendor_diff = None
 
   oem_props = OPTIONS.target_info_dict.get("oem_fingerprint_properties")
-  recovery_mount_options = OPTIONS.target_info_dict.get("recovery_mount_options")
+  recovery_mount_options = OPTIONS.target_info_dict.get(
+      "recovery_mount_options")
   oem_dict = None
   if oem_props is not None and len(oem_props) > 0:
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
     script.Mount("/oem", recovery_mount_options)
-    oem_dict = common.LoadDictionaryFromLines(open(OPTIONS.oem_source).readlines())
+    oem_dict = common.LoadDictionaryFromLines(
+        open(OPTIONS.oem_source).readlines())
 
   AppendAssertions(script, OPTIONS.target_info_dict, oem_dict)
   device_specific.IncrementalOTA_Assertions()
@@ -792,7 +806,8 @@
   #       patch system files, etc.
   #       force full install of new boot image
   #       set up system to update recovery partition on first boot
-  #    complete script normally (allow recovery to mark itself finished and reboot)
+  #    complete script normally
+  #    (allow recovery to mark itself finished and reboot)
 
   if OPTIONS.two_step:
     if not OPTIONS.info_dict.get("multistage_support", None):
@@ -805,7 +820,7 @@
     script.AppendExtra("""
 if get_stage("%(bcb_dev)s") == "2/3" then
 """ % bcb_dev)
-    script.AppendExtra("sleep(20);\n");
+    script.AppendExtra("sleep(20);\n")
     script.WriteRawImage("/recovery", "recovery.img")
     script.AppendExtra("""
 set_stage("%(bcb_dev)s", "3/3");
@@ -929,8 +944,9 @@
   WriteMetadata(metadata, output_zip)
 
 
-class FileDifference:
+class FileDifference(object):
   def __init__(self, partition, source_zip, target_zip, output_zip):
+    self.deferred_patch_list = None
     print "Loading target..."
     self.target_data = target_data = LoadPartitionFiles(target_zip, partition)
     print "Loading source..."
@@ -1003,7 +1019,7 @@
 
   def EmitVerification(self, script):
     so_far = 0
-    for tf, sf, size, patch_sha in self.patch_list:
+    for tf, sf, _, _ in self.patch_list:
       if tf.name != sf.name:
         script.SkipNextActionIfTargetExists(tf.name, tf.sha1)
       script.PatchCheck("/"+sf.name, tf.sha1, sf.sha1)
@@ -1011,18 +1027,18 @@
     return so_far
 
   def EmitExplicitTargetVerification(self, script):
-    for fn, size, sha1 in self.verbatim_targets:
-      if (fn[-1] != "/"):
+    for fn, _, sha1 in self.verbatim_targets:
+      if fn[-1] != "/":
         script.FileCheck("/"+fn, sha1)
     for tf, _, _, _ in self.patch_list:
       script.FileCheck(tf.name, tf.sha1)
 
   def RemoveUnneededFiles(self, script, extras=()):
-    script.DeleteFiles(["/"+i[0] for i in self.verbatim_targets] +
-                       ["/"+i for i in sorted(self.source_data)
-                              if i not in self.target_data and
-                              i not in self.renames] +
-                       list(extras))
+    script.DeleteFiles(
+        ["/" + i[0] for i in self.verbatim_targets] +
+        ["/" + i for i in sorted(self.source_data)
+         if i not in self.target_data and i not in self.renames] +
+        list(extras))
 
   def TotalPatchSize(self):
     return sum(i[1].size for i in self.patch_list)
@@ -1030,22 +1046,24 @@
   def EmitPatches(self, script, total_patch_size, so_far):
     self.deferred_patch_list = deferred_patch_list = []
     for item in self.patch_list:
-      tf, sf, size, _ = item
+      tf, sf, _, _ = item
       if tf.name == "system/build.prop":
         deferred_patch_list.append(item)
         continue
-      if (sf.name != tf.name):
+      if sf.name != tf.name:
         script.SkipNextActionIfTargetExists(tf.name, tf.sha1)
-      script.ApplyPatch("/"+sf.name, "-", tf.size, tf.sha1, sf.sha1, "patch/"+sf.name+".p")
+      script.ApplyPatch("/" + sf.name, "-", tf.size, tf.sha1, sf.sha1,
+                        "patch/" + sf.name + ".p")
       so_far += tf.size
       script.SetProgress(so_far / total_patch_size)
     return so_far
 
   def EmitDeferredPatches(self, script):
     for item in self.deferred_patch_list:
-      tf, sf, size, _ = item
-      script.ApplyPatch("/"+sf.name, "-", tf.size, tf.sha1, sf.sha1, "patch/"+sf.name+".p")
-    script.SetPermissions("/system/build.prop", 0, 0, 0644, None, None)
+      tf, sf, _, _ = item
+      script.ApplyPatch("/"+sf.name, "-", tf.size, tf.sha1, sf.sha1,
+                        "patch/" + sf.name + ".p")
+    script.SetPermissions("/system/build.prop", 0, 0, 0o644, None, None)
 
   def EmitRenames(self, script):
     if len(self.renames) > 0:
@@ -1055,8 +1073,6 @@
         script.RenameFile(src, tgt.name)
 
 
-
-
 def WriteIncrementalOTAPackage(target_zip, source_zip, output_zip):
   target_has_recovery_patch = HasRecoveryPatch(target_zip)
   source_has_recovery_patch = HasRecoveryPatch(source_zip)
@@ -1082,13 +1098,15 @@
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
     script.Mount("/oem", recovery_mount_options)
-    oem_dict = common.LoadDictionaryFromLines(open(OPTIONS.oem_source).readlines())
+    oem_dict = common.LoadDictionaryFromLines(
+        open(OPTIONS.oem_source).readlines())
 
-  metadata = {"pre-device": GetOemProperty("ro.product.device", oem_props, oem_dict,
-                                         OPTIONS.source_info_dict),
-              "post-timestamp": GetBuildProp("ro.build.date.utc",
-                                             OPTIONS.target_info_dict),
-              }
+  metadata = {
+      "pre-device": GetOemProperty("ro.product.device", oem_props, oem_dict,
+                                   OPTIONS.source_info_dict),
+      "post-timestamp": GetBuildProp("ro.build.date.utc",
+                                     OPTIONS.target_info_dict),
+  }
 
   device_specific = common.DeviceSpecificParams(
       source_zip=source_zip,
@@ -1108,8 +1126,10 @@
   else:
     vendor_diff = None
 
-  target_fp = CalculateFingerprint(oem_props, oem_dict, OPTIONS.target_info_dict)
-  source_fp = CalculateFingerprint(oem_props, oem_dict, OPTIONS.source_info_dict)
+  target_fp = CalculateFingerprint(oem_props, oem_dict,
+                                   OPTIONS.target_info_dict)
+  source_fp = CalculateFingerprint(oem_props, oem_dict,
+                                   OPTIONS.source_info_dict)
 
   if oem_props is None:
     script.AssertSomeFingerprint(source_fp, target_fp)
@@ -1164,7 +1184,8 @@
   #       patch system files, etc.
   #       force full install of new boot image
   #       set up system to update recovery partition on first boot
-  #    complete script normally (allow recovery to mark itself finished and reboot)
+  #    complete script normally
+  #    (allow recovery to mark itself finished and reboot)
 
   if OPTIONS.two_step:
     if not OPTIONS.info_dict.get("multistage_support", None):
@@ -1177,7 +1198,7 @@
     script.AppendExtra("""
 if get_stage("%(bcb_dev)s") == "2/3" then
 """ % bcb_dev)
-    script.AppendExtra("sleep(20);\n");
+    script.AppendExtra("sleep(20);\n")
     script.WriteRawImage("/recovery", "recovery.img")
     script.AppendExtra("""
 set_stage("%(bcb_dev)s", "3/3");
@@ -1211,9 +1232,11 @@
     so_far += source_boot.size
 
   size = []
-  if system_diff.patch_list: size.append(system_diff.largest_source_size)
+  if system_diff.patch_list:
+    size.append(system_diff.largest_source_size)
   if vendor_diff:
-    if vendor_diff.patch_list: size.append(vendor_diff.largest_source_size)
+    if vendor_diff.patch_list:
+      size.append(vendor_diff.largest_source_size)
   if size or updating_recovery or updating_boot:
     script.CacheFreeSpaceCheck(max(size))
 
@@ -1290,7 +1313,7 @@
     if not target_has_recovery_patch:
       def output_sink(fn, data):
         common.ZipWriteStr(output_zip, "recovery/" + fn, data)
-        system_items.Get("system/" + fn, dir=False)
+        system_items.Get("system/" + fn)
 
       common.MakeRecoveryPatch(OPTIONS.target_tmp, output_sink,
                                target_recovery, target_boot)
@@ -1436,7 +1459,7 @@
       OPTIONS.two_step = True
     elif o == "--no_signing":
       OPTIONS.no_signing = True
-    elif o in ("--verify"):
+    elif o == "--verify":
       OPTIONS.verify = True
     elif o == "--block":
       OPTIONS.block_based = True
@@ -1450,23 +1473,23 @@
 
   args = common.ParseOptions(argv, __doc__,
                              extra_opts="b:k:i:d:wne:t:a:2o:",
-                             extra_long_opts=["board_config=",
-                                              "package_key=",
-                                              "incremental_from=",
-                                              "wipe_user_data",
-                                              "no_prereq",
-                                              "extra_script=",
-                                              "worker_threads=",
-                                              "aslr_mode=",
-                                              "two_step",
-                                              "no_signing",
-                                              "block",
-                                              "binary=",
-                                              "oem_settings=",
-                                              "verify",
-                                              "no_fallback_to_full",
-                                              ],
-                             extra_option_handler=option_handler)
+                             extra_long_opts=[
+                                 "board_config=",
+                                 "package_key=",
+                                 "incremental_from=",
+                                 "wipe_user_data",
+                                 "no_prereq",
+                                 "extra_script=",
+                                 "worker_threads=",
+                                 "aslr_mode=",
+                                 "two_step",
+                                 "no_signing",
+                                 "block",
+                                 "binary=",
+                                 "oem_settings=",
+                                 "verify",
+                                 "no_fallback_to_full",
+                             ], extra_option_handler=option_handler)
 
   if len(args) != 2:
     common.Usage(__doc__)
@@ -1486,8 +1509,8 @@
   # is in the out/ directory tree, but for repacking from target-files.zip it's
   # in the root directory of the ramdisk.
   if "selinux_fc" in OPTIONS.info_dict:
-    OPTIONS.info_dict["selinux_fc"] = os.path.join(OPTIONS.input_tmp, "BOOT", "RAMDISK",
-        "file_contexts")
+    OPTIONS.info_dict["selinux_fc"] = os.path.join(
+        OPTIONS.input_tmp, "BOOT", "RAMDISK", "file_contexts")
 
   if OPTIONS.verbose:
     print "--- target info ---"
@@ -1514,8 +1537,10 @@
   while True:
 
     if OPTIONS.no_signing:
-      if os.path.exists(args[1]): os.unlink(args[1])
-      output_zip = zipfile.ZipFile(args[1], "w", compression=zipfile.ZIP_DEFLATED)
+      if os.path.exists(args[1]):
+        os.unlink(args[1])
+      output_zip = zipfile.ZipFile(args[1], "w",
+                                   compression=zipfile.ZIP_DEFLATED)
     else:
       temp_zip_file = tempfile.NamedTemporaryFile()
       output_zip = zipfile.ZipFile(temp_zip_file, "w",
@@ -1531,12 +1556,13 @@
 
     else:
       print "unzipping source target-files..."
-      OPTIONS.source_tmp, source_zip = common.UnzipTemp(OPTIONS.incremental_source)
+      OPTIONS.source_tmp, source_zip = common.UnzipTemp(
+          OPTIONS.incremental_source)
       OPTIONS.target_info_dict = OPTIONS.info_dict
       OPTIONS.source_info_dict = common.LoadInfoDict(source_zip)
       if "selinux_fc" in OPTIONS.source_info_dict:
-        OPTIONS.source_info_dict["selinux_fc"] = os.path.join(OPTIONS.source_tmp, "BOOT", "RAMDISK",
-                                                              "file_contexts")
+        OPTIONS.source_info_dict["selinux_fc"] = os.path.join(
+            OPTIONS.source_tmp, "BOOT", "RAMDISK", "file_contexts")
       if OPTIONS.package_key is None:
         OPTIONS.package_key = OPTIONS.source_info_dict.get(
             "default_system_dev_certificate",
@@ -1548,7 +1574,8 @@
         WriteIncrementalOTAPackage(input_zip, source_zip, output_zip)
         break
       except ValueError:
-        if not OPTIONS.fallback_to_full: raise
+        if not OPTIONS.fallback_to_full:
+          raise
         print "--- failed to build incremental; falling back to full ---"
         OPTIONS.incremental_source = None
         output_zip.close()
@@ -1566,7 +1593,7 @@
   try:
     common.CloseInheritedPipes()
     main(sys.argv[1:])
-  except common.ExternalError, e:
+  except common.ExternalError as e:
     print
     print "   ERROR: %s" % (e,)
     print
diff --git a/tools/releasetools/pylintrc b/tools/releasetools/pylintrc
new file mode 100644
index 0000000..90de1af
--- /dev/null
+++ b/tools/releasetools/pylintrc
@@ -0,0 +1,382 @@
+[MASTER]
+
+# Specify a configuration file.
+#rcfile=
+
+# Python code to execute, usually for sys.path manipulation such as
+# pygtk.require().
+#init-hook=
+
+# Profiled execution.
+profile=no
+
+# Add files or directories to the blacklist. They should be base names, not
+# paths.
+ignore=CVS
+
+# Pickle collected data for later comparisons.
+persistent=yes
+
+# List of plugins (as comma separated values of python modules names) to load,
+# usually to register additional checkers.
+load-plugins=
+
+# Use multiple processes to speed up Pylint.
+jobs=1
+
+# Allow loading of arbitrary C extensions. Extensions are imported into the
+# active Python interpreter and may run arbitrary code.
+unsafe-load-any-extension=no
+
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code
+extension-pkg-whitelist=
+
+# Allow optimization of some AST trees. This will activate a peephole AST
+# optimizer, which will apply various small optimizations. For instance, it can
+# be used to obtain the result of joining multiple strings with the addition
+# operator. Joining a lot of strings can lead to a maximum recursion error in
+# Pylint and this flag can prevent that. It has one side effect, the resulting
+# AST will be different than the one from reality.
+optimize-ast=no
+
+
+[MESSAGES CONTROL]
+
+# Only show warnings with the listed confidence levels. Leave empty to show
+# all. Valid levels: HIGH, INFERENCE, INFERENCE_FAILURE, UNDEFINED
+confidence=
+
+# Enable the message, report, category or checker with the given id(s). You can
+# either give multiple identifier separated by comma (,) or put this option
+# multiple time. See also the "--disable" option for examples.
+#enable=
+
+# Disable the message, report, category or checker with the given id(s). You
+# can either give multiple identifiers separated by comma (,) or put this
+# option multiple times (only on the command line, not in the configuration
+# file where it should appear only once).You can also use "--disable=all" to
+# disable everything first and then reenable specific checks. For example, if
+# you want to run only the similarities checker, you can use "--disable=all
+# --enable=similarities". If you want to run only the classes checker, but have
+# no Warning level messages displayed, use"--disable=all --enable=classes
+# --disable=W"
+disable=invalid-name,missing-docstring,too-many-branches,too-many-locals,too-many-arguments,too-many-statements,duplicate-code,too-few-public-methods,too-many-instance-attributes,too-many-lines,too-many-public-methods,locally-disabled,fixme
+
+
+[REPORTS]
+
+# Set the output format. Available formats are text, parseable, colorized, msvs
+# (visual studio) and html. You can also give a reporter class, eg
+# mypackage.mymodule.MyReporterClass.
+output-format=text
+
+# Put messages in a separate file for each module / package specified on the
+# command line instead of printing them on stdout. Reports (if any) will be
+# written in a file name "pylint_global.[txt|html]".
+files-output=no
+
+# Tells whether to display a full report or only the messages
+reports=yes
+
+# Python expression which should return a note less than 10 (10 is the highest
+# note). You have access to the variables errors warning, statement which
+# respectively contain the number of errors / warnings messages and the total
+# number of statements analyzed. This is used by the global evaluation report
+# (RP0004).
+evaluation=10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10)
+
+# Add a comment according to your evaluation note. This is used by the global
+# evaluation report (RP0004).
+comment=no
+
+# Template used to display messages. This is a python new-style format string
+# used to format the message information. See doc for all details
+#msg-template=
+
+
+[SIMILARITIES]
+
+# Minimum lines number of a similarity.
+min-similarity-lines=4
+
+# Ignore comments when computing similarities.
+ignore-comments=yes
+
+# Ignore docstrings when computing similarities.
+ignore-docstrings=yes
+
+# Ignore imports when computing similarities.
+ignore-imports=no
+
+
+[TYPECHECK]
+
+# Tells whether missing members accessed in mixin class should be ignored. A
+# mixin class is detected if its name ends with "mixin" (case insensitive).
+ignore-mixin-members=yes
+
+# List of module names for which member attributes should not be checked
+# (useful for modules/projects where namespaces are manipulated during runtime
+# and thus existing member attributes cannot be deduced by static analysis
+ignored-modules=
+
+# List of classes names for which member attributes should not be checked
+# (useful for classes with attributes dynamically set).
+ignored-classes=SQLObject
+
+# When zope mode is activated, add a predefined set of Zope acquired attributes
+# to generated-members.
+zope=no
+
+# List of members which are set dynamically and missed by pylint inference
+# system, and so shouldn't trigger E0201 when accessed. Python regular
+# expressions are accepted.
+generated-members=REQUEST,acl_users,aq_parent
+
+
+[MISCELLANEOUS]
+
+# List of note tags to take in consideration, separated by a comma.
+notes=FIXME,XXX,TODO
+
+
+[BASIC]
+
+# Required attributes for module, separated by a comma
+required-attributes=
+
+# List of builtins function names that should not be used, separated by a comma
+bad-functions=map,filter,input
+
+# Good variable names which should always be accepted, separated by a comma
+good-names=i,j,k,ex,Run,_
+
+# Bad variable names which should always be refused, separated by a comma
+bad-names=foo,bar,baz,toto,tutu,tata
+
+# Colon-delimited sets of names that determine each other's naming style when
+# the name regexes allow several styles.
+name-group=
+
+# Include a hint for the correct naming format with invalid-name
+include-naming-hint=no
+
+# Regular expression matching correct function names
+function-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Naming hint for function names
+function-name-hint=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression matching correct variable names
+variable-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Naming hint for variable names
+variable-name-hint=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression matching correct constant names
+const-rgx=(([A-Z_][A-Z0-9_]*)|(__.*__))$
+
+# Naming hint for constant names
+const-name-hint=(([A-Z_][A-Z0-9_]*)|(__.*__))$
+
+# Regular expression matching correct attribute names
+attr-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Naming hint for attribute names
+attr-name-hint=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression matching correct argument names
+argument-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Naming hint for argument names
+argument-name-hint=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression matching correct class attribute names
+class-attribute-rgx=([A-Za-z_][A-Za-z0-9_]{2,30}|(__.*__))$
+
+# Naming hint for class attribute names
+class-attribute-name-hint=([A-Za-z_][A-Za-z0-9_]{2,30}|(__.*__))$
+
+# Regular expression matching correct inline iteration names
+inlinevar-rgx=[A-Za-z_][A-Za-z0-9_]*$
+
+# Naming hint for inline iteration names
+inlinevar-name-hint=[A-Za-z_][A-Za-z0-9_]*$
+
+# Regular expression matching correct class names
+class-rgx=[A-Z_][a-zA-Z0-9]+$
+
+# Naming hint for class names
+class-name-hint=[A-Z_][a-zA-Z0-9]+$
+
+# Regular expression matching correct module names
+module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$
+
+# Naming hint for module names
+module-name-hint=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$
+
+# Regular expression matching correct method names
+method-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Naming hint for method names
+method-name-hint=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression which should only match function or class names that do
+# not require a docstring.
+no-docstring-rgx=__.*__
+
+# Minimum line length for functions/classes that require docstrings, shorter
+# ones are exempt.
+docstring-min-length=-1
+
+
+[SPELLING]
+
+# Spelling dictionary name. Available dictionaries: none. To make it working
+# install python-enchant package.
+spelling-dict=
+
+# List of comma separated words that should not be checked.
+spelling-ignore-words=
+
+# A path to a file that contains private dictionary; one word per line.
+spelling-private-dict-file=
+
+# Tells whether to store unknown words to indicated private dictionary in
+# --spelling-private-dict-file option instead of raising a message.
+spelling-store-unknown-words=no
+
+
+[FORMAT]
+
+# Maximum number of characters on a single line.
+max-line-length=80
+
+# Regexp for a line that is allowed to be longer than the limit.
+ignore-long-lines=^\s*(# )?<?https?://\S+>?$
+
+# Allow the body of an if to be on the same line as the test if there is no
+# else.
+single-line-if-stmt=no
+
+# List of optional constructs for which whitespace checking is disabled
+no-space-check=trailing-comma,dict-separator
+
+# Maximum number of lines in a module
+max-module-lines=1000
+
+# String used as indentation unit. This is usually " " (4 spaces) or "\t" (1
+# tab).
+indent-string='  '
+
+# Number of spaces of indent required inside a hanging or continued line.
+indent-after-paren=4
+
+# Expected format of line ending, e.g. empty (any line ending), LF or CRLF.
+expected-line-ending-format=LF
+
+
+[LOGGING]
+
+# Logging modules to check that the string format arguments are in logging
+# function parameter format
+logging-modules=logging
+
+
+[VARIABLES]
+
+# Tells whether we should check for unused import in __init__ files.
+init-import=no
+
+# A regular expression matching the name of dummy variables (i.e. expectedly
+# not used).
+dummy-variables-rgx=_$|dummy
+
+# List of additional names supposed to be defined in builtins. Remember that
+# you should avoid to define new builtins when possible.
+additional-builtins=
+
+# List of strings which can identify a callback function by name. A callback
+# name must start or end with one of those strings.
+callbacks=cb_,_cb
+
+
+[DESIGN]
+
+# Maximum number of arguments for function / method
+max-args=5
+
+# Argument names that match this expression will be ignored. Default to name
+# with leading underscore
+ignored-argument-names=_.*
+
+# Maximum number of locals for function / method body
+max-locals=15
+
+# Maximum number of return / yield for function / method body
+max-returns=6
+
+# Maximum number of branch for function / method body
+max-branches=12
+
+# Maximum number of statements in function / method body
+max-statements=50
+
+# Maximum number of parents for a class (see R0901).
+max-parents=7
+
+# Maximum number of attributes for a class (see R0902).
+max-attributes=7
+
+# Minimum number of public methods for a class (see R0903).
+min-public-methods=2
+
+# Maximum number of public methods for a class (see R0904).
+max-public-methods=20
+
+
+[IMPORTS]
+
+# Deprecated modules which should not be used, separated by a comma
+deprecated-modules=regsub,TERMIOS,Bastion,rexec
+
+# Create a graph of every (i.e. internal and external) dependencies in the
+# given file (report RP0402 must not be disabled)
+import-graph=
+
+# Create a graph of external dependencies in the given file (report RP0402 must
+# not be disabled)
+ext-import-graph=
+
+# Create a graph of internal dependencies in the given file (report RP0402 must
+# not be disabled)
+int-import-graph=
+
+
+[CLASSES]
+
+# List of interface methods to ignore, separated by a comma. This is used for
+# instance to not check methods defines in Zope's Interface base class.
+ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by
+
+# List of method names used to declare (i.e. assign) instance attributes.
+defining-attr-methods=__init__,__new__,setUp
+
+# List of valid names for the first argument in a class method.
+valid-classmethod-first-arg=cls
+
+# List of valid names for the first argument in a metaclass class method.
+valid-metaclass-classmethod-first-arg=mcs
+
+# List of member names, which should be excluded from the protected access
+# warning.
+exclude-protected=_asdict,_fields,_replace,_source,_make
+
+
+[EXCEPTIONS]
+
+# Exceptions that will emit a warning when being caught. Defaults to
+# "Exception"
+overgeneral-exceptions=Exception
diff --git a/tools/releasetools/rangelib.py b/tools/releasetools/rangelib.py
index 7279c60..8b327fe 100644
--- a/tools/releasetools/rangelib.py
+++ b/tools/releasetools/rangelib.py
@@ -24,6 +24,7 @@
   lots of runs."""
 
   def __init__(self, data=None):
+    self.monotonic = False
     if isinstance(data, str):
       self._parse_internal(data)
     elif data:
@@ -185,7 +186,7 @@
     # This is like intersect, but we can stop as soon as we discover the
     # output is going to be nonempty.
     z = 0
-    for p, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
+    for _, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
                             zip(other.data, itertools.cycle((+1, -1)))):
       if (z == 1 and d == 1) or (z == 2 and d == -1):
         return True
diff --git a/tools/releasetools/sign_target_files_apks b/tools/releasetools/sign_target_files_apks
new file mode 120000
index 0000000..b5ec59a
--- /dev/null
+++ b/tools/releasetools/sign_target_files_apks
@@ -0,0 +1 @@
+sign_target_files_apks.py
\ No newline at end of file
diff --git a/tools/releasetools/sign_target_files_apks b/tools/releasetools/sign_target_files_apks.py
similarity index 94%
rename from tools/releasetools/sign_target_files_apks
rename to tools/releasetools/sign_target_files_apks.py
index 9e61051..d47cc4f 100755
--- a/tools/releasetools/sign_target_files_apks
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -169,22 +169,25 @@
           f.write(data)
 
   for info in input_tf_zip.infolist():
-    if info.filename.startswith("IMAGES/"): continue
+    if info.filename.startswith("IMAGES/"):
+      continue
 
     data = input_tf_zip.read(info.filename)
     out_info = copy.copy(info)
 
     if (info.filename == "META/misc_info.txt" and
         OPTIONS.replace_verity_private_key):
-      ReplaceVerityPrivateKey(input_tf_zip, output_tf_zip, misc_info, OPTIONS.replace_verity_private_key[1])
+      ReplaceVerityPrivateKey(input_tf_zip, output_tf_zip, misc_info,
+                              OPTIONS.replace_verity_private_key[1])
     elif (info.filename == "BOOT/RAMDISK/verity_key" and
-        OPTIONS.replace_verity_public_key):
-      new_data = ReplaceVerityPublicKey(output_tf_zip, OPTIONS.replace_verity_public_key[1])
+          OPTIONS.replace_verity_public_key):
+      new_data = ReplaceVerityPublicKey(output_tf_zip,
+                                        OPTIONS.replace_verity_public_key[1])
       write_to_temp(info.filename, info.external_attr, new_data)
     elif (info.filename.startswith("BOOT/") or
-        info.filename.startswith("RECOVERY/") or
-        info.filename.startswith("META/") or
-        info.filename == "SYSTEM/etc/recovery-resource.dat"):
+          info.filename.startswith("RECOVERY/") or
+          info.filename.startswith("META/") or
+          info.filename == "SYSTEM/etc/recovery-resource.dat"):
       write_to_temp(info.filename, info.external_attr, data)
 
     if info.filename.endswith(".apk"):
@@ -231,7 +234,7 @@
   if OPTIONS.replace_ota_keys:
     new_recovery_keys = ReplaceOtaKeys(input_tf_zip, output_tf_zip, misc_info)
     if new_recovery_keys:
-      write_to_temp("RECOVERY/RAMDISK/res/keys", 0755 << 16, new_recovery_keys)
+      write_to_temp("RECOVERY/RAMDISK/res/keys", 0o755 << 16, new_recovery_keys)
 
   if rebuild_recovery:
     recovery_img = common.GetBootableImage(
@@ -268,8 +271,8 @@
       if OPTIONS.verbose:
         print "    Replaced %d occurence(s) of %s.x509.pem with " \
             "%s.x509.pem" % (num, old, new)
-    except IOError, e:
-      if (e.errno == errno.ENOENT and not OPTIONS.verbose):
+    except IOError as e:
+      if e.errno == errno.ENOENT and not OPTIONS.verbose:
         continue
 
       print "    Error accessing %s. %s. Skip replacing %s.x509.pem " \
@@ -303,7 +306,7 @@
         pieces[-1] = EditTags(pieces[-1])
         value = "/".join(pieces)
       elif (key in ("ro.build.thumbprint", "ro.vendor.build.thumbprint")
-          and misc_info.get("oem_fingerprint_properties") is not None):
+            and misc_info.get("oem_fingerprint_properties") is not None):
         pieces = value.split("/")
         pieces[-1] = EditTags(pieces[-1])
         value = "/".join(pieces)
@@ -380,13 +383,13 @@
   # put into a zipfile system/etc/security/otacerts.zip.
   # We DO NOT include the extra_recovery_keys (if any) here.
 
-  tempfile = cStringIO.StringIO()
-  certs_zip = zipfile.ZipFile(tempfile, "w")
+  temp_file = cStringIO.StringIO()
+  certs_zip = zipfile.ZipFile(temp_file, "w")
   for k in mapped_keys:
     certs_zip.write(k)
   certs_zip.close()
   common.ZipWriteStr(output_tf_zip, "SYSTEM/etc/security/otacerts.zip",
-                     tempfile.getvalue())
+                     temp_file.getvalue())
 
   return new_recovery_keys
 
@@ -397,7 +400,8 @@
   common.ZipWriteStr(targetfile_zip, "BOOT/RAMDISK/verity_key", data)
   return data
 
-def ReplaceVerityPrivateKey(targetfile_input_zip, targetfile_output_zip, misc_info, key_path):
+def ReplaceVerityPrivateKey(targetfile_input_zip, targetfile_output_zip,
+                            misc_info, key_path):
   print "Replacing verity private key with %s" % key_path
   current_key = misc_info["verity_key"]
   original_misc_info = targetfile_input_zip.read("META/misc_info.txt")
diff --git a/tools/releasetools/sparse_img.py b/tools/releasetools/sparse_img.py
index 7574747..b97bb84 100644
--- a/tools/releasetools/sparse_img.py
+++ b/tools/releasetools/sparse_img.py
@@ -14,12 +14,11 @@
 
 import bisect
 import os
-import sys
 import struct
-import pprint
 from hashlib import sha1
 
-from rangelib import *
+import rangelib
+
 
 class SparseImage(object):
   """Wraps a sparse image file (and optional file map) into an image
@@ -39,7 +38,6 @@
     self.blocksize = blk_sz = header[5]
     self.total_blocks = total_blks = header[6]
     total_chunks = header[7]
-    image_checksum = header[8]
 
     if magic != 0xED26FF3A:
       raise ValueError("Magic should be 0xED26FF3A but is 0x%08X" % (magic,))
@@ -64,7 +62,6 @@
       header_bin = f.read(12)
       header = struct.unpack("<2H2I", header_bin)
       chunk_type = header[0]
-      reserved1 = header[1]
       chunk_sz = header[2]
       total_sz = header[3]
       data_sz = total_sz - 12
@@ -102,7 +99,7 @@
         raise ValueError("Unknown chunk type 0x%04X not supported" %
                          (chunk_type,))
 
-    self.care_map = RangeSet(care_data)
+    self.care_map = rangelib.RangeSet(care_data)
     self.offset_index = [i[0] for i in offset_map]
 
     if file_map_fn:
@@ -166,7 +163,7 @@
     with open(fn) as f:
       for line in f:
         fn, ranges = line.split(None, 1)
-        ranges = RangeSet.parse(ranges)
+        ranges = rangelib.RangeSet.parse(ranges)
         out[fn] = ranges
         assert ranges.size() == ranges.intersect(remaining).size()
         remaining = remaining.subtract(ranges)
@@ -186,7 +183,7 @@
     for s, e in remaining:
       for b in range(s, e):
         idx = bisect.bisect_right(self.offset_index, b) - 1
-        chunk_start, chunk_len, filepos, fill_data = self.offset_map[idx]
+        chunk_start, _, filepos, fill_data = self.offset_map[idx]
         if filepos is not None:
           filepos += (b-chunk_start) * self.blocksize
           f.seek(filepos, os.SEEK_SET)
@@ -204,8 +201,8 @@
           nonzero_blocks.append(b)
           nonzero_blocks.append(b+1)
 
-    out["__ZERO"] = RangeSet(data=zero_blocks)
-    out["__NONZERO"] = RangeSet(data=nonzero_blocks)
+    out["__ZERO"] = rangelib.RangeSet(data=zero_blocks)
+    out["__NONZERO"] = rangelib.RangeSet(data=nonzero_blocks)
 
   def ResetFileMap(self):
     """Throw away the file map and treat the entire image as