diff --git a/file_descriptor.cc b/file_descriptor.cc
new file mode 100644
index 0000000..275aa70
--- /dev/null
+++ b/file_descriptor.cc
@@ -0,0 +1,57 @@
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "update_engine/file_descriptor.h"
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <base/eintr_wrapper.h>
+
+namespace chromeos_update_engine {
+
+bool EintrSafeFileDescriptor::Open(const char* path, int flags, mode_t mode) {
+  CHECK_EQ(fd_, -1);
+  return ((fd_ = HANDLE_EINTR(open(path, flags, mode))) >= 0);
+}
+
+bool EintrSafeFileDescriptor::Open(const char* path, int flags) {
+  CHECK_EQ(fd_, -1);
+  return ((fd_ = HANDLE_EINTR(open(path, flags))) >= 0);
+}
+
+ssize_t EintrSafeFileDescriptor::Read(void* buf, size_t count) {
+  CHECK_GE(fd_, 0);
+  return HANDLE_EINTR(read(fd_, buf, count));
+}
+
+ssize_t EintrSafeFileDescriptor::Write(const void* buf, size_t count) {
+  CHECK_GE(fd_, 0);
+
+  // Attempt repeated writes, as long as some progress is being made.
+  char* char_buf = const_cast<char*>(reinterpret_cast<const char*>(buf));
+  ssize_t written = 0;
+  while (count > 0) {
+    ssize_t ret = HANDLE_EINTR(write(fd_, char_buf, count));
+
+    // Fail on either an error or no progress.
+    if (ret <= 0)
+      return (written ? written : ret);
+    written += ret;
+    count -= ret;
+    char_buf += ret;
+  }
+  return written;
+}
+
+bool EintrSafeFileDescriptor::Close() {
+  CHECK_GE(fd_, 0);
+  int ret = HANDLE_EINTR(close(fd_));
+  if (!ret)
+    fd_ = -1;
+  return !ret;
+}
+
+}  // namespace chromeos_update_engine