diff --git a/subprocess.cc b/subprocess.cc
new file mode 100644
index 0000000..299d758
--- /dev/null
+++ b/subprocess.cc
@@ -0,0 +1,108 @@
+// Copyright (c) 2009 The Chromium 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/subprocess.h"
+#include <stdlib.h>
+#include <string.h>
+#include <string>
+#include <vector>
+#include "chromeos/obsolete_logging.h"
+#include "base/scoped_ptr.h"
+
+using std::string;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+void Subprocess::GChildExitedCallback(GPid pid, gint status, gpointer data) {
+  COMPILE_ASSERT(sizeof(guint) == sizeof(uint32),
+                 guint_uint32_size_mismatch);
+  guint *tag = reinterpret_cast<guint*>(data);
+  const SubprocessCallbackRecord& record = Get().callback_records_[*tag];
+  if (record.callback)
+    record.callback(status, record.callback_data);
+  g_spawn_close_pid(pid);
+  Get().callback_records_.erase(*tag);
+  delete tag;
+}
+
+namespace {
+void FreeArgv(char** argv) {
+  for (int i = 0; argv[i]; i++) {
+    free(argv[i]);
+    argv[i] = NULL;
+  }
+}
+}  // namespace {}
+
+uint32 Subprocess::Exec(const std::vector<std::string>& cmd,
+                        ExecCallback callback,
+                        void *p) {
+  GPid child_pid;
+  GError *err;
+  scoped_array<char *> argv(new char*[cmd.size() + 1]);
+  for (unsigned int i = 0; i < cmd.size(); i++) {
+    argv[i] = strdup(cmd[i].c_str());
+  }
+  argv[cmd.size()] = NULL;
+  char *argp[1];
+  argp[0] = NULL;
+
+  SubprocessCallbackRecord callback_record;
+  callback_record.callback = callback;
+  callback_record.callback_data = p;
+
+  bool success = g_spawn_async(NULL,  // working directory
+                               argv.get(),
+                               argp,
+                               G_SPAWN_DO_NOT_REAP_CHILD,  // flags
+                               NULL,  // child setup function
+                               NULL,  // child setup data pointer
+                               &child_pid,
+                               &err);
+  FreeArgv(argv.get());
+  if (!success) {
+    LOG(ERROR) << "g_spawn_async failed";
+    return 0;
+  }
+  guint *tag = new guint;
+  *tag = g_child_watch_add(child_pid, GChildExitedCallback, tag);
+  callback_records_[*tag] = callback_record;
+  return *tag;
+}
+
+void Subprocess::CancelExec(uint32 tag) {
+  if (callback_records_[tag].callback) {
+    callback_records_[tag].callback = NULL;
+  }
+}
+
+bool Subprocess::SynchronousExec(const std::vector<std::string>& cmd,
+                                 int* return_code) {
+  GError *err;
+  scoped_array<char *> argv(new char*[cmd.size() + 1]);
+  for (unsigned int i = 0; i < cmd.size(); i++) {
+    argv[i] = strdup(cmd[i].c_str());
+  }
+  argv[cmd.size()] = NULL;
+  char *argp[1];
+  argp[0] = NULL;
+
+  bool success = g_spawn_sync(NULL,  // working directory
+                              argv.get(),
+                              argp,
+                              static_cast<GSpawnFlags>(NULL),  // flags
+                              NULL,  // child setup function
+                              NULL,  // data for child setup function
+                              NULL,  // return location for stdout
+                              NULL,  // return location for stderr
+                              return_code,
+                              &err);
+  FreeArgv(argv.get());
+  return success;
+}
+
+Subprocess* Subprocess::subprocess_singleton_ = NULL;
+
+}  // namespace chromeos_update_engine