diff --git a/libs/androidfw/FileStream.cpp b/libs/androidfw/FileStream.cpp
new file mode 100644
index 0000000..b86c9cb
--- /dev/null
+++ b/libs/androidfw/FileStream.cpp
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#include "androidfw/FileStream.h"
+
+#include <errno.h>   // for errno
+#include <fcntl.h>   // for O_RDONLY
+#include <unistd.h>  // for read
+
+#include "android-base/errors.h"
+#include "android-base/file.h"  // for O_BINARY
+#include "android-base/macros.h"
+#include "android-base/utf8.h"
+
+#if defined(_WIN32)
+// This is only needed for O_CLOEXEC.
+#include <windows.h>
+#define O_CLOEXEC O_NOINHERIT
+#endif
+
+using ::android::base::SystemErrorCodeToString;
+using ::android::base::unique_fd;
+
+namespace android {
+
+FileInputStream::FileInputStream(const std::string& path, size_t buffer_capacity)
+    : buffer_capacity_(buffer_capacity) {
+  int mode = O_RDONLY | O_CLOEXEC | O_BINARY;
+  fd_.reset(TEMP_FAILURE_RETRY(::android::base::utf8::open(path.c_str(), mode)));
+  if (fd_ == -1) {
+    error_ = SystemErrorCodeToString(errno);
+  } else {
+    buffer_.reset(new uint8_t[buffer_capacity_]);
+  }
+}
+
+FileInputStream::FileInputStream(int fd, size_t buffer_capacity)
+    : fd_(fd), buffer_capacity_(buffer_capacity) {
+  if (fd_ < 0) {
+    error_ = "Bad File Descriptor";
+  } else {
+    buffer_.reset(new uint8_t[buffer_capacity_]);
+  }
+}
+
+bool FileInputStream::Next(const void** data, size_t* size) {
+  if (HadError()) {
+    return false;
+  }
+
+  // Deal with any remaining bytes after BackUp was called.
+  if (buffer_offset_ != buffer_size_) {
+    *data = buffer_.get() + buffer_offset_;
+    *size = buffer_size_ - buffer_offset_;
+    total_byte_count_ += buffer_size_ - buffer_offset_;
+    buffer_offset_ = buffer_size_;
+    return true;
+  }
+
+  ssize_t n = TEMP_FAILURE_RETRY(read(fd_, buffer_.get(), buffer_capacity_));
+  if (n < 0) {
+    error_ = SystemErrorCodeToString(errno);
+    fd_.reset();
+    buffer_.reset();
+    return false;
+  }
+
+  buffer_size_ = static_cast<size_t>(n);
+  buffer_offset_ = buffer_size_;
+  total_byte_count_ += buffer_size_;
+
+  *data = buffer_.get();
+  *size = buffer_size_;
+  return buffer_size_ != 0u;
+}
+
+void FileInputStream::BackUp(size_t count) {
+  if (count > buffer_offset_) {
+    count = buffer_offset_;
+  }
+  buffer_offset_ -= count;
+  total_byte_count_ -= count;
+}
+
+size_t FileInputStream::ByteCount() const {
+  return total_byte_count_;
+}
+
+bool FileInputStream::HadError() const {
+  return fd_ == -1;
+}
+
+std::string FileInputStream::GetError() const {
+  return error_;
+}
+
+bool FileInputStream::ReadFullyAtOffset(void* data, size_t byte_count, off64_t offset) {
+  return base::ReadFullyAtOffset(fd_, data, byte_count, offset);
+}
+
+FileOutputStream::FileOutputStream(const std::string& path, size_t buffer_capacity)
+    : buffer_capacity_(buffer_capacity) {
+  int mode = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_BINARY;
+  owned_fd_.reset(TEMP_FAILURE_RETRY(::android::base::utf8::open(path.c_str(), mode, 0666)));
+  fd_ = owned_fd_.get();
+  if (fd_ < 0) {
+    error_ = SystemErrorCodeToString(errno);
+  } else {
+    buffer_.reset(new uint8_t[buffer_capacity_]);
+  }
+}
+
+FileOutputStream::FileOutputStream(unique_fd fd, size_t buffer_capacity)
+    : FileOutputStream(fd.get(), buffer_capacity) {
+  owned_fd_ = std::move(fd);
+}
+
+FileOutputStream::FileOutputStream(int fd, size_t buffer_capacity)
+    : fd_(fd), buffer_capacity_(buffer_capacity) {
+  if (fd_ < 0) {
+    error_ = "Bad File Descriptor";
+  } else {
+    buffer_.reset(new uint8_t[buffer_capacity_]);
+  }
+}
+
+FileOutputStream::~FileOutputStream() {
+  // Flush the buffer.
+  Flush();
+}
+
+bool FileOutputStream::Next(void** data, size_t* size) {
+  if (HadError()) {
+    return false;
+  }
+
+  if (buffer_offset_ == buffer_capacity_) {
+    if (!FlushImpl()) {
+      return false;
+    }
+  }
+
+  const size_t buffer_size = buffer_capacity_ - buffer_offset_;
+  *data = buffer_.get() + buffer_offset_;
+  *size = buffer_size;
+  total_byte_count_ += buffer_size;
+  buffer_offset_ = buffer_capacity_;
+  return true;
+}
+
+void FileOutputStream::BackUp(size_t count) {
+  if (count > buffer_offset_) {
+    count = buffer_offset_;
+  }
+  buffer_offset_ -= count;
+  total_byte_count_ -= count;
+}
+
+size_t FileOutputStream::ByteCount() const {
+  return total_byte_count_;
+}
+
+bool FileOutputStream::Flush() {
+  if (!HadError()) {
+    return FlushImpl();
+  }
+  return false;
+}
+
+bool FileOutputStream::FlushImpl() {
+  ssize_t n = TEMP_FAILURE_RETRY(write(fd_, buffer_.get(), buffer_offset_));
+  if (n < 0) {
+    error_ = SystemErrorCodeToString(errno);
+    owned_fd_.reset();
+    fd_ = -1;
+    buffer_.reset();
+    return false;
+  }
+
+  buffer_offset_ = 0u;
+  return true;
+}
+
+bool FileOutputStream::HadError() const {
+  return fd_ == -1;
+}
+
+std::string FileOutputStream::GetError() const {
+  return error_;
+}
+
+}  // namespace android