diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 940ac1d..06de622 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -754,6 +754,33 @@
   return ReadBytesFromInputFile(input_file, fn).decode()
 
 
+def WriteBytesToInputFile(input_file, fn, data):
+  """Write bytes |data| contents to fn of input zipfile or directory."""
+  if isinstance(input_file, zipfile.ZipFile):
+    with input_file.open(fn, "w") as entry_fp:
+      return entry_fp.write(data)
+  elif zipfile.is_zipfile(input_file):
+    with zipfile.ZipFile(input_file, "r", allowZip64=True) as zfp:
+      with zfp.open(fn, "w") as entry_fp:
+        return entry_fp.write(data)
+  else:
+    if not os.path.isdir(input_file):
+      raise ValueError(
+          "Invalid input_file, accepted inputs are ZipFile object, path to .zip file on disk, or path to extracted directory. Actual: " + input_file)
+    path = os.path.join(input_file, *fn.split("/"))
+    try:
+      with open(path, "wb") as f:
+        return f.write(data)
+    except IOError as e:
+      if e.errno == errno.ENOENT:
+        raise KeyError(fn)
+
+
+def WriteToInputFile(input_file, fn, str: str):
+  """Write str content to fn of input file or directory"""
+  return WriteBytesToInputFile(input_file, fn, str.encode())
+
+
 def ExtractFromInputFile(input_file, fn):
   """Extracts the contents of fn from input zipfile or directory into a file."""
   if isinstance(input_file, zipfile.ZipFile):
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index e40256c..1a4a895 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -270,7 +270,7 @@
 import common
 import ota_utils
 from ota_utils import (UNZIP_PATTERN, FinalizeMetadata, GetPackageMetadata,
-                       PayloadGenerator, SECURITY_PATCH_LEVEL_PROP_NAME, CopyTargetFilesDir)
+                       PayloadGenerator, SECURITY_PATCH_LEVEL_PROP_NAME, ExtractTargetFiles, CopyTargetFilesDir)
 from common import DoesInputFileContain, IsSparseImage
 import target_files_diff
 from check_target_files_vintf import CheckVintfIfTrebleEnabled
@@ -519,15 +519,10 @@
   Returns:
     The filename of target-files.zip that doesn't contain postinstall config.
   """
-  # We should only make a copy if postinstall_config entry exists.
-  with zipfile.ZipFile(input_file, 'r', allowZip64=True) as input_zip:
-    if POSTINSTALL_CONFIG not in input_zip.namelist():
-      return input_file
-
-  target_file = common.MakeTempFile(prefix="targetfiles-", suffix=".zip")
-  shutil.copyfile(input_file, target_file)
-  common.ZipDelete(target_file, POSTINSTALL_CONFIG)
-  return target_file
+  config_path = os.path.join(input_file, POSTINSTALL_CONFIG)
+  if os.path.exists(config_path):
+    os.unlink(config_path)
+  return input_file
 
 
 def ParseInfoDict(target_file_path):
@@ -544,6 +539,17 @@
   Returns:
     The path to modified target-files.zip
   """
+  if os.path.isdir(input_file):
+    dynamic_partition_info_path = os.path.join(
+        input_file, "META", "dynamic_partitions_info.txt")
+    with open(dynamic_partition_info_path, "r") as fp:
+      dynamic_partition_info = fp.read()
+    dynamic_partition_info = ModifyVABCCompressionParam(
+        dynamic_partition_info, vabc_compression_param)
+    with open(dynamic_partition_info_path, "w") as fp:
+      fp.write(dynamic_partition_info)
+    return input_file
+
   target_file = common.MakeTempFile(prefix="targetfiles-", suffix=".zip")
   shutil.copyfile(input_file, target_file)
   common.ZipDelete(target_file, DYNAMIC_PARTITION_INFO)
@@ -571,23 +577,7 @@
     The filename of target-files.zip used for partial ota update.
   """
 
-  def AddImageForPartition(partition_name):
-    """Add the archive name for a given partition to the copy list."""
-    for prefix in ['IMAGES', 'RADIO']:
-      image_path = '{}/{}.img'.format(prefix, partition_name)
-      if image_path in namelist:
-        copy_entries.append(image_path)
-        map_path = '{}/{}.map'.format(prefix, partition_name)
-        if map_path in namelist:
-          copy_entries.append(map_path)
-        return
-
-    raise ValueError("Cannot find {} in input zipfile".format(partition_name))
-
-  with zipfile.ZipFile(input_file, allowZip64=True) as input_zip:
-    original_ab_partitions = input_zip.read(
-        AB_PARTITIONS).decode().splitlines()
-    namelist = input_zip.namelist()
+  original_ab_partitions = common.ReadFromInputFile(input_file, AB_PARTITIONS)
 
   unrecognized_partitions = [partition for partition in ab_partitions if
                              partition not in original_ab_partitions]
@@ -596,50 +586,65 @@
                      unrecognized_partitions)
 
   logger.info("Generating partial updates for %s", ab_partitions)
+  for subdir in ["IMAGES", "RADIO", "PREBUILT_IMAGES"]:
+    image_dir = os.path.join(subdir)
+    if not os.path.exists(image_dir):
+      continue
+    for filename in os.listdir(image_dir):
+      filepath = os.path.join(image_dir, filename)
+      if filename.endswith(".img"):
+        partition_name = filename.removesuffix(".img")
+        if partition_name not in ab_partitions:
+          os.unlink(filepath)
 
-  copy_entries = ['META/update_engine_config.txt']
-  for partition_name in ab_partitions:
-    AddImageForPartition(partition_name)
+  common.WriteToInputFile(input_file, 'META/ab_partitions.txt',
+                          '\n'.join(ab_partitions))
+  CARE_MAP_ENTRY = "META/care_map.pb"
+  if DoesInputFileContain(input_file, CARE_MAP_ENTRY):
+    caremap = care_map_pb2.CareMap()
+    caremap.ParseFromString(
+        common.ReadBytesFromInputFile(input_file, CARE_MAP_ENTRY))
+    filtered = [
+        part for part in caremap.partitions if part.name in ab_partitions]
+    del caremap.partitions[:]
+    caremap.partitions.extend(filtered)
+    common.WriteBytesToInputFile(input_file, CARE_MAP_ENTRY,
+                                 caremap.SerializeToString())
 
-  # Use zip2zip to avoid extracting the zipfile.
-  partial_target_file = common.MakeTempFile(suffix='.zip')
-  cmd = ['zip2zip', '-i', input_file, '-o', partial_target_file]
-  cmd.extend(['{}:{}'.format(name, name) for name in copy_entries])
-  common.RunAndCheckOutput(cmd)
+  for info_file in ['META/misc_info.txt', DYNAMIC_PARTITION_INFO]:
+    if not DoesInputFileContain(input_file, info_file):
+      logger.warning('Cannot find %s in input zipfile', info_file)
+      continue
 
-  partial_target_zip = zipfile.ZipFile(partial_target_file, 'a',
-                                       allowZip64=True)
-  with zipfile.ZipFile(input_file, allowZip64=True) as input_zip:
-    common.ZipWriteStr(partial_target_zip, 'META/ab_partitions.txt',
-                       '\n'.join(ab_partitions))
-    CARE_MAP_ENTRY = "META/care_map.pb"
-    if CARE_MAP_ENTRY in input_zip.namelist():
-      caremap = care_map_pb2.CareMap()
-      caremap.ParseFromString(input_zip.read(CARE_MAP_ENTRY))
-      filtered = [
-          part for part in caremap.partitions if part.name in ab_partitions]
-      del caremap.partitions[:]
-      caremap.partitions.extend(filtered)
-      common.ZipWriteStr(partial_target_zip, CARE_MAP_ENTRY,
-                         caremap.SerializeToString())
+    content = common.ReadFromInputFile(input_file, info_file)
+    modified_info = UpdatesInfoForSpecialUpdates(
+        content, lambda p: p in ab_partitions)
+    if OPTIONS.vabc_compression_param and info_file == DYNAMIC_PARTITION_INFO:
+      modified_info = ModifyVABCCompressionParam(
+          modified_info, OPTIONS.vabc_compression_param)
+    common.WriteToInputFile(input_file, info_file, modified_info)
 
-    for info_file in ['META/misc_info.txt', DYNAMIC_PARTITION_INFO]:
-      if info_file not in input_zip.namelist():
-        logger.warning('Cannot find %s in input zipfile', info_file)
-        continue
-      content = input_zip.read(info_file).decode()
-      modified_info = UpdatesInfoForSpecialUpdates(
-          content, lambda p: p in ab_partitions)
-      if OPTIONS.vabc_compression_param and info_file == DYNAMIC_PARTITION_INFO:
-        modified_info = ModifyVABCCompressionParam(
-            modified_info, OPTIONS.vabc_compression_param)
-      common.ZipWriteStr(partial_target_zip, info_file, modified_info)
+  def IsInPartialList(postinstall_line: str):
+    idx = postinstall_line.find("=")
+    if idx < 0:
+      return False
+    key = postinstall_line[:idx]
+    logger.info("%s %s", key, ab_partitions)
+    for part in ab_partitions:
+      if key.endswith("_" + part):
+        return True
+    return False
 
-    # TODO(xunchang) handle META/postinstall_config.txt'
+  postinstall_config = common.ReadFromInputFile(input_file, POSTINSTALL_CONFIG)
+  postinstall_config = [
+      line for line in postinstall_config.splitlines() if IsInPartialList(line)]
+  if postinstall_config:
+    postinstall_config = "\n".join(postinstall_config)
+    common.WriteToInputFile(input_file, POSTINSTALL_CONFIG, postinstall_config)
+  else:
+    os.unlink(os.path.join(input_file, POSTINSTALL_CONFIG))
 
-  common.ZipClose(partial_target_zip)
-
-  return partial_target_file
+  return input_file
 
 
 def GetTargetFilesZipForRetrofitDynamicPartitions(input_file,
@@ -664,21 +669,12 @@
   replace = {'OTA/super_{}.img'.format(dev): 'IMAGES/{}.img'.format(dev)
              for dev in super_block_devices}
 
-  target_file = common.MakeTempFile(prefix="targetfiles-", suffix=".zip")
-  shutil.copyfile(input_file, target_file)
-
-  with zipfile.ZipFile(input_file, allowZip64=True) as input_zip:
-    namelist = input_zip.namelist()
-
-  input_tmp = common.UnzipTemp(input_file, RETROFIT_DAP_UNZIP_PATTERN)
-
   # Remove partitions from META/ab_partitions.txt that is in
   # dynamic_partition_list but not in super_block_devices so that
   # brillo_update_payload won't generate update for those logical partitions.
-  ab_partitions_file = os.path.join(input_tmp, *AB_PARTITIONS.split('/'))
-  with open(ab_partitions_file) as f:
-    ab_partitions_lines = f.readlines()
-    ab_partitions = [line.strip() for line in ab_partitions_lines]
+  ab_partitions_lines = common.ReadFromInputFile(
+      input_file, AB_PARTITIONS).split("\n")
+  ab_partitions = [line.strip() for line in ab_partitions_lines]
   # Assert that all super_block_devices are in ab_partitions
   super_device_not_updated = [partition for partition in super_block_devices
                               if partition not in ab_partitions]
@@ -686,15 +682,6 @@
       "{} is in super_block_devices but not in {}".format(
           super_device_not_updated, AB_PARTITIONS)
   # ab_partitions -= (dynamic_partition_list - super_block_devices)
-  new_ab_partitions = common.MakeTempFile(
-      prefix="ab_partitions", suffix=".txt")
-  with open(new_ab_partitions, 'w') as f:
-    for partition in ab_partitions:
-      if (partition in dynamic_partition_list and
-              partition not in super_block_devices):
-        logger.info("Dropping %s from ab_partitions.txt", partition)
-        continue
-      f.write(partition + "\n")
   to_delete = [AB_PARTITIONS]
 
   # Always skip postinstall for a retrofit update.
@@ -707,24 +694,28 @@
   # Remove the existing partition images as well as the map files.
   to_delete += list(replace.values())
   to_delete += ['IMAGES/{}.map'.format(dev) for dev in super_block_devices]
-
-  common.ZipDelete(target_file, to_delete)
-
-  target_zip = zipfile.ZipFile(target_file, 'a', allowZip64=True)
+  for item in to_delete:
+    os.unlink(os.path.join(input_file, item))
 
   # Write super_{foo}.img as {foo}.img.
   for src, dst in replace.items():
-    assert src in namelist, \
+    assert DoesInputFileContain(input_file, src), \
         'Missing {} in {}; {} cannot be written'.format(src, input_file, dst)
-    unzipped_file = os.path.join(input_tmp, *src.split('/'))
-    common.ZipWrite(target_zip, unzipped_file, arcname=dst)
+    source_path = os.path.join(input_file, *src.split("/"))
+    target_path = os.path.join(input_file, *dst.split("/"))
+    os.rename(source_path, target_path)
 
   # Write new ab_partitions.txt file
-  common.ZipWrite(target_zip, new_ab_partitions, arcname=AB_PARTITIONS)
+  new_ab_partitions = os.paht.join(input_file, AB_PARTITIONS)
+  with open(new_ab_partitions, 'w') as f:
+    for partition in ab_partitions:
+      if (partition in dynamic_partition_list and
+              partition not in super_block_devices):
+        logger.info("Dropping %s from ab_partitions.txt", partition)
+        continue
+      f.write(partition + "\n")
 
-  common.ZipClose(target_zip)
-
-  return target_file
+  return input_file
 
 
 def GetTargetFilesZipForCustomImagesUpdates(input_file, custom_images):
@@ -833,14 +824,20 @@
   return pattern.search(output) is not None
 
 
+def ExtractOrCopyTargetFiles(target_file):
+  if os.path.isdir(target_file):
+    return CopyTargetFilesDir(target_file)
+  else:
+    return ExtractTargetFiles(target_file)
+
+
 def GenerateAbOtaPackage(target_file, output_file, source_file=None):
   """Generates an Android OTA package that has A/B update payload."""
   # If input target_files are directories, create a copy so that we can modify
   # them directly
-  if os.path.isdir(target_file):
-    target_file = CopyTargetFilesDir(target_file)
-  if source_file is not None and os.path.isdir(source_file):
-    source_file = CopyTargetFilesDir(source_file)
+  target_file = ExtractOrCopyTargetFiles(target_file)
+  if source_file is not None:
+    source_file = ExtractOrCopyTargetFiles(source_file)
   # Stage the output zip package for package signing.
   if not OPTIONS.no_signing:
     staging_file = common.MakeTempFile(suffix='.zip')
@@ -851,7 +848,7 @@
                                allowZip64=True)
 
   if source_file is not None:
-    source_file = ota_utils.ExtractTargetFiles(source_file)
+    source_file = ExtractTargetFiles(source_file)
     assert "ab_partitions" in OPTIONS.source_info_dict, \
         "META/ab_partitions.txt is required for ab_update."
     assert "ab_partitions" in OPTIONS.target_info_dict, \
@@ -948,10 +945,10 @@
   elif OPTIONS.partial:
     target_file = GetTargetFilesZipForPartialUpdates(target_file,
                                                      OPTIONS.partial)
-  elif OPTIONS.vabc_compression_param:
+  if OPTIONS.vabc_compression_param:
     target_file = GetTargetFilesZipForCustomVABCCompression(
         target_file, OPTIONS.vabc_compression_param)
-  elif OPTIONS.skip_postinstall:
+  if OPTIONS.skip_postinstall:
     target_file = GetTargetFilesZipWithoutPostinstallConfig(target_file)
   # Target_file may have been modified, reparse ab_partitions
   target_info.info_dict['ab_partitions'] = common.ReadFromInputFile(target_file,
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index 3291d56..9067e78 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -1047,10 +1047,15 @@
 
 def CopyTargetFilesDir(input_dir):
   output_dir = common.MakeTempDir("target_files")
-  shutil.copytree(os.path.join(input_dir, "IMAGES"), os.path.join(
-      output_dir, "IMAGES"), dirs_exist_ok=True)
+  IMAGES_DIR = ["IMAGES", "PREBUILT_IMAGES", "RADIO"]
+  for subdir in IMAGES_DIR:
+    if not os.path.exists(os.path.join(input_dir, subdir)):
+      continue
+    shutil.copytree(os.path.join(input_dir, subdir), os.path.join(
+        output_dir, subdir), dirs_exist_ok=True, copy_function=os.link)
   shutil.copytree(os.path.join(input_dir, "META"), os.path.join(
       output_dir, "META"), dirs_exist_ok=True)
+
   for (dirpath, _, filenames) in os.walk(input_dir):
     for filename in filenames:
       path = os.path.join(dirpath, filename)