diff --git a/tools/releasetools/add_img_to_target_files.py b/tools/releasetools/add_img_to_target_files.py
index 7984ad6..eab8113 100755
--- a/tools/releasetools/add_img_to_target_files.py
+++ b/tools/releasetools/add_img_to_target_files.py
@@ -33,10 +33,6 @@
 import tempfile
 import zipfile
 
-# missing in Python 2.4 and before
-if not hasattr(os, "SEEK_SET"):
-  os.SEEK_SET = 0
-
 import build_image
 import common
 
@@ -189,7 +185,7 @@
   assert succ, "build userdata.img image failed"
 
   common.CheckSize(img.name, "userdata.img", OPTIONS.info_dict)
-  output_zip.write(img.name, prefix + "userdata.img")
+  common.ZipWrite(output_zip, img.name, prefix + "userdata.img")
   img.close()
   os.rmdir(user_dir)
   os.rmdir(temp_dir)
@@ -226,7 +222,7 @@
   assert succ, "build cache.img image failed"
 
   common.CheckSize(img.name, "cache.img", OPTIONS.info_dict)
-  output_zip.write(img.name, prefix + "cache.img")
+  common.ZipWrite(output_zip, img.name, prefix + "cache.img")
   img.close()
   os.rmdir(user_dir)
   os.rmdir(temp_dir)
@@ -252,7 +248,7 @@
     OPTIONS.info_dict["selinux_fc"] = os.path.join(
         OPTIONS.input_tmp, "BOOT", "RAMDISK", "file_contexts")
 
-  input_zip.close()
+  common.ZipClose(input_zip)
   output_zip = zipfile.ZipFile(filename, "a",
                                compression=zipfile.ZIP_DEFLATED)
 
@@ -297,7 +293,7 @@
   banner("cache")
   AddCache(output_zip)
 
-  output_zip.close()
+  common.ZipClose(output_zip)
 
 def main(argv):
   def option_handler(o, _):
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index 04ced09..cbcad6d 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -205,8 +205,8 @@
   Returns:
     True iff the image is built successfully.
   """
-  # system_root_image=true: build a system.img that combines the contents of /system
-  # and the ramdisk, and can be mounted at the root of the file system.
+  # system_root_image=true: build a system.img that combines the contents of
+  # /system and the ramdisk, and can be mounted at the root of the file system.
   origin_in = in_dir
   fs_config = prop_dict.get("fs_config")
   if (prop_dict.get("system_root_image") == "true"
@@ -375,8 +375,8 @@
     copy_prop("system_size", "partition_size")
     copy_prop("system_journal_size", "journal_size")
     copy_prop("system_verity_block_device", "verity_block_device")
-    copy_prop("system_root_image","system_root_image")
-    copy_prop("ramdisk_dir","ramdisk_dir")
+    copy_prop("system_root_image", "system_root_image")
+    copy_prop("ramdisk_dir", "ramdisk_dir")
   elif mount_point == "data":
     # Copy the generic fs type first, override with specific one if available.
     copy_prop("fs_type", "fs_type")
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index e05ee3c..ab58fa7 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -32,10 +32,7 @@
 import blockimgdiff
 import rangelib
 
-try:
-  from hashlib import sha1 as sha1
-except ImportError:
-  from sha import sha as sha1
+from hashlib import sha1 as sha1
 
 
 class Options(object):
@@ -384,6 +381,10 @@
     p.communicate()
     assert p.returncode == 0, "vboot_signer of %s image failed" % path
 
+    # Clean up the temp files.
+    img_unsigned.close()
+    img_keyblock.close()
+
   img.seek(os.SEEK_SET, 0)
   data = img.read()
 
@@ -861,16 +862,50 @@
     zipfile.ZIP64_LIMIT = saved_zip64_limit
 
 
-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:
+def ZipWriteStr(zip_file, zinfo_or_arcname, data, perms=0o644,
+                compress_type=None):
+  """Wrap zipfile.writestr() function to work around the zip64 limit.
+
+  Even with the ZIP64_LIMIT workaround, it won't allow writing a string
+  longer than 2GiB. It gives 'OverflowError: size does not fit in an int'
+  when calling crc32(bytes).
+
+  But it still works fine to write a shorter string into a large zip file.
+  We should use ZipWrite() whenever possible, and only use ZipWriteStr()
+  when we know the string won't be too long.
+  """
+
+  saved_zip64_limit = zipfile.ZIP64_LIMIT
+  zipfile.ZIP64_LIMIT = (1 << 32) - 1
+
+  if not isinstance(zinfo_or_arcname, zipfile.ZipInfo):
+    zinfo = zipfile.ZipInfo(filename=zinfo_or_arcname)
     zinfo.compress_type = zip_file.compression
   else:
-    zinfo.compress_type = compression
+    zinfo = zinfo_or_arcname
+
+  # If compress_type is given, it overrides the value in zinfo.
+  if compress_type is not None:
+    zinfo.compress_type = compress_type
+
+  # Use a fixed timestamp so the output is repeatable.
   zinfo.external_attr = perms << 16
+  zinfo.date_time = (2009, 1, 1, 0, 0, 0)
+
   zip_file.writestr(zinfo, data)
+  zipfile.ZIP64_LIMIT = saved_zip64_limit
+
+
+def ZipClose(zip_file):
+  # http://b/18015246
+  # zipfile also refers to ZIP64_LIMIT during close() when it writes out the
+  # central directory.
+  saved_zip64_limit = zipfile.ZIP64_LIMIT
+  zipfile.ZIP64_LIMIT = (1 << 32) - 1
+
+  zip_file.close()
+
+  zipfile.ZIP64_LIMIT = saved_zip64_limit
 
 
 class DeviceSpecificParams(object):
@@ -976,7 +1011,7 @@
     return t
 
   def AddToZip(self, z, compression=None):
-    ZipWriteStr(z, self.name, self.data, compression=compression)
+    ZipWriteStr(z, self.name, self.data, compress_type=compression)
 
 DIFF_PROGRAM_BY_EXT = {
     ".gz" : "imgdiff",
diff --git a/tools/releasetools/img_from_target_files.py b/tools/releasetools/img_from_target_files.py
index 8c5acd8..c486992 100755
--- a/tools/releasetools/img_from_target_files.py
+++ b/tools/releasetools/img_from_target_files.py
@@ -43,8 +43,9 @@
 
 def CopyInfo(output_zip):
   """Copy the android-info.txt file from the input to the output."""
-  output_zip.write(os.path.join(OPTIONS.input_tmp, "OTA", "android-info.txt"),
-                   "android-info.txt")
+  common.ZipWrite(
+      output_zip, os.path.join(OPTIONS.input_tmp, "OTA", "android-info.txt"),
+      "android-info.txt")
 
 
 def main(argv):
@@ -133,13 +134,7 @@
 
   finally:
     print "cleaning up..."
-    # http://b/18015246
-    # See common.py for context.  zipfile also refers to ZIP64_LIMIT during
-    # close() when it writes out the central directory.
-    saved_zip64_limit = zipfile.ZIP64_LIMIT
-    zipfile.ZIP64_LIMIT = (1 << 32) - 1
-    output_zip.close()
-    zipfile.ZIP64_LIMIT = saved_zip64_limit
+    common.ZipClose(output_zip)
     shutil.rmtree(OPTIONS.input_tmp)
 
   print "done."
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index eab3daa..900eaec 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -92,7 +92,6 @@
   print >> sys.stderr, "Python 2.7 or newer is required."
   sys.exit(1)
 
-import copy
 import multiprocessing
 import os
 import tempfile
@@ -371,6 +370,7 @@
         symlinks.append((input_zip.read(info.filename),
                          "/" + partition + "/" + basefilename))
       else:
+        import copy
         info2 = copy.copy(info)
         fn = info2.filename = partition + "/" + basefilename
         if substitute and fn in substitute and substitute[fn] is None:
@@ -380,7 +380,7 @@
             data = substitute[fn]
           else:
             data = input_zip.read(info.filename)
-          output_zip.writestr(info2, data)
+          common.ZipWriteStr(output_zip, info2, data)
         if fn.endswith("/"):
           itemset.Get(fn[:-1], is_dir=True)
         else:
@@ -1581,6 +1581,7 @@
         OPTIONS.package_key = OPTIONS.info_dict.get(
             "default_system_dev_certificate",
             "build/target/product/security/testkey")
+      common.ZipClose(output_zip)
       break
 
     else:
@@ -1601,15 +1602,14 @@
         common.DumpInfoDict(OPTIONS.source_info_dict)
       try:
         WriteIncrementalOTAPackage(input_zip, source_zip, output_zip)
+        common.ZipClose(output_zip)
         break
       except ValueError:
         if not OPTIONS.fallback_to_full:
           raise
         print "--- failed to build incremental; falling back to full ---"
         OPTIONS.incremental_source = None
-        output_zip.close()
-
-  output_zip.close()
+        common.ZipClose(output_zip)
 
   if not OPTIONS.no_signing:
     SignOutput(temp_zip_file.name, args[1])
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index d47cc4f..ec49112 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -196,23 +196,23 @@
       if key not in common.SPECIAL_CERT_STRINGS:
         print "    signing: %-*s (%s)" % (maxsize, name, key)
         signed_data = SignApk(data, key, key_passwords[key])
-        output_tf_zip.writestr(out_info, signed_data)
+        common.ZipWriteStr(output_tf_zip, out_info, signed_data)
       else:
         # an APK we're not supposed to sign.
         print "NOT signing: %s" % (name,)
-        output_tf_zip.writestr(out_info, data)
+        common.ZipWriteStr(output_tf_zip, out_info, data)
     elif info.filename in ("SYSTEM/build.prop",
                            "VENDOR/build.prop",
                            "RECOVERY/RAMDISK/default.prop"):
       print "rewriting %s:" % (info.filename,)
       new_data = RewriteProps(data, misc_info)
-      output_tf_zip.writestr(out_info, new_data)
+      common.ZipWriteStr(output_tf_zip, out_info, new_data)
       if info.filename == "RECOVERY/RAMDISK/default.prop":
         write_to_temp(info.filename, info.external_attr, new_data)
     elif info.filename.endswith("mac_permissions.xml"):
       print "rewriting %s with new keys." % (info.filename,)
       new_data = ReplaceCerts(data)
-      output_tf_zip.writestr(out_info, new_data)
+      common.ZipWriteStr(output_tf_zip, out_info, new_data)
     elif info.filename in ("SYSTEM/recovery-from-boot.p",
                            "SYSTEM/bin/install-recovery.sh"):
       rebuild_recovery = True
@@ -229,7 +229,7 @@
       pass
     else:
       # a non-APK file; copy it verbatim
-      output_tf_zip.writestr(out_info, data)
+      common.ZipWriteStr(output_tf_zip, out_info, data)
 
   if OPTIONS.replace_ota_keys:
     new_recovery_keys = ReplaceOtaKeys(input_tf_zip, output_tf_zip, misc_info)
@@ -243,7 +243,7 @@
         "boot.img", "boot.img", tmpdir, "BOOT", info_dict=misc_info)
 
     def output_sink(fn, data):
-      output_tf_zip.writestr("SYSTEM/"+fn, data)
+      common.ZipWriteStr(output_tf_zip, "SYSTEM/" + fn, data)
 
     common.MakeRecoveryPatch(tmpdir, output_sink, recovery_img, boot_img,
                              info_dict=misc_info)
@@ -488,8 +488,8 @@
   ProcessTargetFiles(input_zip, output_zip, misc_info,
                      apk_key_map, key_passwords)
 
-  input_zip.close()
-  output_zip.close()
+  common.ZipClose(input_zip)
+  common.ZipClose(output_zip)
 
   add_img_to_target_files.AddImagesToTargetFiles(args[1])
 
diff --git a/tools/releasetools/test_common.py b/tools/releasetools/test_common.py
index 5fdc132..f28934d 100644
--- a/tools/releasetools/test_common.py
+++ b/tools/releasetools/test_common.py
@@ -29,15 +29,54 @@
     data[begin:end] = os.urandom(block_size)
   return "".join(data)
 
+def get_2gb_string():
+  kilobytes = 1024
+  megabytes = 1024 * kilobytes
+  gigabytes = 1024 * megabytes
+
+  size = int(2 * gigabytes + 1)
+  block_size = 4 * kilobytes
+  step_size = 4 * megabytes
+  two_gb_string = random_string_with_holes(
+        size, block_size, step_size)
+  return two_gb_string
+
 
 class CommonZipTest(unittest.TestCase):
+  def _verify(self, zip_file, zip_file_name, arcname, contents,
+              test_file_name=None, expected_stat=None, expected_mode=0o644,
+              expected_compress_type=zipfile.ZIP_STORED):
+    # Verify the stat if present.
+    if test_file_name is not None:
+      new_stat = os.stat(test_file_name)
+      self.assertEqual(int(expected_stat.st_mode), int(new_stat.st_mode))
+      self.assertEqual(int(expected_stat.st_mtime), int(new_stat.st_mtime))
+
+    # Reopen the zip file to verify.
+    zip_file = zipfile.ZipFile(zip_file_name, "r")
+
+    # Verify the timestamp.
+    info = zip_file.getinfo(arcname)
+    self.assertEqual(info.date_time, (2009, 1, 1, 0, 0, 0))
+
+    # Verify the file mode.
+    mode = (info.external_attr >> 16) & 0o777
+    self.assertEqual(mode, expected_mode)
+
+    # Verify the compress type.
+    self.assertEqual(info.compress_type, expected_compress_type)
+
+    # Verify the zip contents.
+    self.assertEqual(zip_file.read(arcname), contents)
+    self.assertIsNone(zip_file.testzip())
+
   def _test_ZipWrite(self, contents, extra_zipwrite_args=None):
     extra_zipwrite_args = dict(extra_zipwrite_args or {})
 
     test_file = tempfile.NamedTemporaryFile(delete=False)
-    zip_file = tempfile.NamedTemporaryFile(delete=False)
-
     test_file_name = test_file.name
+
+    zip_file = tempfile.NamedTemporaryFile(delete=False)
     zip_file_name = zip_file.name
 
     # File names within an archive strip the leading slash.
@@ -52,31 +91,100 @@
       test_file.write(contents)
       test_file.close()
 
-      old_stat = os.stat(test_file_name)
+      expected_stat = os.stat(test_file_name)
       expected_mode = extra_zipwrite_args.get("perms", 0o644)
-
+      expected_compress_type = extra_zipwrite_args.get("compress_type",
+                                                       zipfile.ZIP_STORED)
       time.sleep(5)  # Make sure the atime/mtime will change measurably.
 
       common.ZipWrite(zip_file, test_file_name, **extra_zipwrite_args)
+      common.ZipClose(zip_file)
 
-      new_stat = os.stat(test_file_name)
-      self.assertEqual(int(old_stat.st_mode), int(new_stat.st_mode))
-      self.assertEqual(int(old_stat.st_mtime), int(new_stat.st_mtime))
-      self.assertIsNone(zip_file.testzip())
-
-      zip_file.close()
-      zip_file = zipfile.ZipFile(zip_file_name, "r")
-      info = zip_file.getinfo(arcname)
-
-      self.assertEqual(info.date_time, (2009, 1, 1, 0, 0, 0))
-      mode = (info.external_attr >> 16) & 0o777
-      self.assertEqual(mode, expected_mode)
-      self.assertEqual(zip_file.read(arcname), contents)
-      self.assertIsNone(zip_file.testzip())
+      self._verify(zip_file, zip_file_name, arcname, contents, test_file_name,
+                   expected_stat, expected_mode, expected_compress_type)
     finally:
       os.remove(test_file_name)
       os.remove(zip_file_name)
 
+  def _test_ZipWriteStr(self, zinfo_or_arcname, contents, extra_args=None):
+    extra_args = dict(extra_args or {})
+
+    zip_file = tempfile.NamedTemporaryFile(delete=False)
+    zip_file_name = zip_file.name
+    zip_file.close()
+
+    zip_file = zipfile.ZipFile(zip_file_name, "w")
+
+    try:
+      expected_compress_type = extra_args.get("compress_type",
+                                              zipfile.ZIP_STORED)
+      time.sleep(5)  # Make sure the atime/mtime will change measurably.
+
+      if not isinstance(zinfo_or_arcname, zipfile.ZipInfo):
+        zinfo = zipfile.ZipInfo(filename=zinfo_or_arcname)
+      else:
+        zinfo = zinfo_or_arcname
+      arcname = zinfo.filename
+
+      common.ZipWriteStr(zip_file, zinfo, contents, **extra_args)
+      common.ZipClose(zip_file)
+
+      self._verify(zip_file, zip_file_name, arcname, contents,
+                   expected_compress_type=expected_compress_type)
+    finally:
+      os.remove(zip_file_name)
+
+  def _test_ZipWriteStr_large_file(self, large, small, extra_args=None):
+    extra_args = dict(extra_args or {})
+
+    zip_file = tempfile.NamedTemporaryFile(delete=False)
+    zip_file_name = zip_file.name
+
+    test_file = tempfile.NamedTemporaryFile(delete=False)
+    test_file_name = test_file.name
+
+    arcname_large = test_file_name
+    arcname_small = "bar"
+
+    # File names within an archive strip the leading slash.
+    if arcname_large[0] == "/":
+      arcname_large = arcname_large[1:]
+
+    zip_file.close()
+    zip_file = zipfile.ZipFile(zip_file_name, "w")
+
+    try:
+      test_file.write(large)
+      test_file.close()
+
+      expected_stat = os.stat(test_file_name)
+      expected_mode = 0o644
+      expected_compress_type = extra_args.get("compress_type",
+                                              zipfile.ZIP_STORED)
+      time.sleep(5)  # Make sure the atime/mtime will change measurably.
+
+      common.ZipWrite(zip_file, test_file_name, **extra_args)
+      common.ZipWriteStr(zip_file, arcname_small, small, **extra_args)
+      common.ZipClose(zip_file)
+
+      # Verify the contents written by ZipWrite().
+      self._verify(zip_file, zip_file_name, arcname_large, large,
+                   test_file_name, expected_stat, expected_mode,
+                   expected_compress_type)
+
+      # Verify the contents written by ZipWriteStr().
+      self._verify(zip_file, zip_file_name, arcname_small, small,
+                   expected_compress_type=expected_compress_type)
+    finally:
+      os.remove(zip_file_name)
+      os.remove(test_file_name)
+
+  def _test_reset_ZIP64_LIMIT(self, func, *args):
+    default_limit = (1 << 31) - 1
+    self.assertEqual(default_limit, zipfile.ZIP64_LIMIT)
+    func(*args)
+    self.assertEqual(default_limit, zipfile.ZIP64_LIMIT)
+
   def test_ZipWrite(self):
     file_contents = os.urandom(1024)
     self._test_ZipWrite(file_contents)
@@ -88,23 +196,64 @@
         "perms": 0o777,
         "compress_type": zipfile.ZIP_DEFLATED,
     })
+    self._test_ZipWrite(file_contents, {
+        "arcname": "foobar",
+        "perms": 0o700,
+        "compress_type": zipfile.ZIP_STORED,
+    })
 
   def test_ZipWrite_large_file(self):
-    kilobytes = 1024
-    megabytes = 1024 * kilobytes
-    gigabytes = 1024 * megabytes
-
-    size = int(2 * gigabytes + 1)
-    block_size = 4 * kilobytes
-    step_size = 4 * megabytes
-    file_contents = random_string_with_holes(
-        size, block_size, step_size)
+    file_contents = get_2gb_string()
     self._test_ZipWrite(file_contents, {
         "compress_type": zipfile.ZIP_DEFLATED,
     })
 
   def test_ZipWrite_resets_ZIP64_LIMIT(self):
-    default_limit = (1 << 31) - 1
-    self.assertEqual(default_limit, zipfile.ZIP64_LIMIT)
-    self._test_ZipWrite('')
-    self.assertEqual(default_limit, zipfile.ZIP64_LIMIT)
+    self._test_reset_ZIP64_LIMIT(self._test_ZipWrite, "")
+
+  def test_ZipWriteStr(self):
+    random_string = os.urandom(1024)
+    # Passing arcname
+    self._test_ZipWriteStr("foo", random_string)
+
+    # Passing zinfo
+    zinfo = zipfile.ZipInfo(filename="foo")
+    self._test_ZipWriteStr(zinfo, random_string)
+
+    # Timestamp in the zinfo should be overwritten.
+    zinfo.date_time = (2015, 3, 1, 15, 30, 0)
+    self._test_ZipWriteStr(zinfo, random_string)
+
+  def test_ZipWriteStr_with_opts(self):
+    random_string = os.urandom(1024)
+    # Passing arcname
+    self._test_ZipWriteStr("foo", random_string, {
+        "compress_type": zipfile.ZIP_DEFLATED,
+    })
+    self._test_ZipWriteStr("foo", random_string, {
+        "compress_type": zipfile.ZIP_STORED,
+    })
+
+    # Passing zinfo
+    zinfo = zipfile.ZipInfo(filename="foo")
+    self._test_ZipWriteStr(zinfo, random_string, {
+        "compress_type": zipfile.ZIP_DEFLATED,
+    })
+    self._test_ZipWriteStr(zinfo, random_string, {
+        "compress_type": zipfile.ZIP_STORED,
+    })
+
+  def test_ZipWriteStr_large_file(self):
+    # zipfile.writestr() doesn't work when the str size is over 2GiB even with
+    # the workaround. We will only test the case of writing a string into a
+    # large archive.
+    long_string = get_2gb_string()
+    short_string = os.urandom(1024)
+    self._test_ZipWriteStr_large_file(long_string, short_string, {
+        "compress_type": zipfile.ZIP_DEFLATED,
+    })
+
+  def test_ZipWriteStr_resets_ZIP64_LIMIT(self):
+    self._test_reset_ZIP64_LIMIT(self._test_ZipWriteStr, "foo", "")
+    zinfo = zipfile.ZipInfo(filename="foo")
+    self._test_reset_ZIP64_LIMIT(self._test_ZipWriteStr, zinfo, "")