diff --git a/updater/include/updater/build_info.h b/updater/include/updater/build_info.h
new file mode 100644
index 0000000..a1355e8
--- /dev/null
+++ b/updater/include/updater/build_info.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <list>
+#include <map>
+#include <string>
+#include <string_view>
+
+#include <android-base/file.h>
+
+// This class serves as the aggregation of the fake block device information during update
+// simulation on host. In specific, it has the name of the block device, its mount point, and the
+// path to the temporary file that fakes this block device.
+class FakeBlockDevice {
+ public:
+  FakeBlockDevice(std::string block_device, std::string mount_point, std::string temp_file_path)
+      : blockdev_name(std::move(block_device)),
+        mount_point(std::move(mount_point)),
+        mounted_file_path(std::move(temp_file_path)) {}
+
+  std::string blockdev_name;
+  std::string mount_point;
+  std::string mounted_file_path;  // path to the temp file that mocks the block device
+};
+
+// This class stores the information of the source build. For example, it creates and maintains
+// the temporary files to simulate the block devices on host. Therefore, the simulator runtime can
+// query the information and run the update on host.
+class BuildInfo {
+ public:
+  explicit BuildInfo(const std::string_view work_dir) : work_dir_(work_dir) {}
+  // Returns the value of the build properties.
+  std::string GetProperty(const std::string_view key, const std::string_view default_value) const;
+  // Returns the path to the mock block device.
+  std::string FindBlockDeviceName(const std::string_view name) const;
+  // Parses the given target-file, initializes the build properties and extracts the images.
+  bool ParseTargetFile(const std::string_view target_file_path, bool extracted_input);
+
+ private:
+  // A map to store the system properties during simulation.
+  std::map<std::string, std::string, std::less<>> build_props_;
+  // A map from the blockdev_name to the FakeBlockDevice object, which contains the path to the
+  // temporary file.
+  std::map<std::string, FakeBlockDevice, std::less<>> blockdev_map_;
+
+  std::list<TemporaryFile> temp_files_;
+  std::string work_dir_;  // A temporary directory to store the extracted image files
+};
diff --git a/updater/include/updater/simulator_runtime.h b/updater/include/updater/simulator_runtime.h
index 93fa2a4..6290958 100644
--- a/updater/include/updater/simulator_runtime.h
+++ b/updater/include/updater/simulator_runtime.h
@@ -24,11 +24,11 @@
 #include <vector>
 
 #include "edify/updater_runtime_interface.h"
-#include "updater/target_files.h"
+#include "updater/build_info.h"
 
 class SimulatorRuntime : public UpdaterRuntimeInterface {
  public:
-  explicit SimulatorRuntime(TargetFiles* source) : source_(source) {}
+  explicit SimulatorRuntime(BuildInfo* source) : source_(source) {}
 
   bool IsSimulator() const override {
     return true;
@@ -53,6 +53,6 @@
  private:
   std::string FindBlockDeviceName(const std::string_view name) const override;
 
-  TargetFiles* source_;
+  BuildInfo* source_;
   std::map<std::string, std::string, std::less<>> mounted_partitions_;
 };
diff --git a/updater/include/updater/target_files.h b/updater/include/updater/target_files.h
index 9ef1a5b..860d47a 100644
--- a/updater/include/updater/target_files.h
+++ b/updater/include/updater/target_files.h
@@ -16,21 +16,56 @@
 
 #pragma once
 
+#include <map>
 #include <string>
+#include <string_view>
+#include <vector>
 
-// This class parses a given target file for the build properties and image files. Then it creates
-// and maintains the temporary files to simulate the block devices on host.
-class TargetFiles {
+#include <android-base/file.h>
+#include <ziparchive/zip_archive.h>
+
+// This class represents the mount information for each line in a fstab file.
+class FstabInfo {
  public:
-  TargetFiles(std::string path, std::string work_dir)
-      : path_(std::move(path)), work_dir_(std::move(work_dir)) {}
+  FstabInfo(std::string blockdev_name, std::string mount_point, std::string fs_type)
+      : blockdev_name(std::move(blockdev_name)),
+        mount_point(std::move(mount_point)),
+        fs_type(std::move(fs_type)) {}
 
-  std::string GetProperty(const std::string_view key, const std::string_view default_value) const;
+  std::string blockdev_name;
+  std::string mount_point;
+  std::string fs_type;
+};
 
-  std::string FindBlockDeviceName(const std::string_view name) const;
+// This class parses a target file from a zip file or an extracted directory. It also provides the
+// function to read the its content for simulation.
+class TargetFile {
+ public:
+  TargetFile(std::string path, bool extracted_input)
+      : path_(std::move(path)), extracted_input_(extracted_input) {}
+
+  // Opens the input target file (or extracted directory) and parses the misc_info.txt.
+  bool Open();
+  // Parses the build properties in all possible locations and save them in |props_map|
+  bool GetBuildProps(std::map<std::string, std::string, std::less<>>* props_map) const;
+  // Parses the fstab and save the information about each partition to mount into |fstab_info_list|.
+  bool ParseFstabInfo(std::vector<FstabInfo>* fstab_info_list) const;
+  // Returns true if the given entry exists in the target file.
+  bool EntryExists(const std::string_view name) const;
+  // Extracts the image file |entry_name|. Returns true on success.
+  bool ExtractImage(const std::string_view entry_name, const FstabInfo& fstab_info,
+                    const std::string_view work_dir, TemporaryFile* image_file) const;
 
  private:
-  std::string path_;  // Path to the target file.
+  // Wrapper functions to read the entry from either the zipped target-file, or the extracted input
+  // directory.
+  bool ReadEntryToString(const std::string_view name, std::string* content) const;
+  bool ExtractEntryToTempFile(const std::string_view name, TemporaryFile* temp_file) const;
 
-  std::string work_dir_;  // A temporary directory to store the extracted image files
+  std::string path_;      // Path to the zipped target-file or an extracted directory.
+  bool extracted_input_;  // True if the target-file has been extracted.
+  ZipArchiveHandle handle_{ nullptr };
+
+  // The properties under META/misc_info.txt
+  std::map<std::string, std::string, std::less<>> misc_info_;
 };