Browser watcher first installment.

components/browser_watcher/watcher_win.cc

+// Copyright (c) 2014 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 "components/browser_watcher/watcher_win.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "base/process/kill.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+#include "base/win/registry.h"
+
+namespace browser_watcher {
+
+namespace {
+
+base::string16 GetValueName(const base::Time creation_time,
+                            base::ProcessId pid) {
+  // Convert the PID and creation time to a string value unique to this
+  // process instance.
+  return base::StringPrintf(L"%d-%lld", pid, creation_time.ToInternalValue());
+}
+
+}  // namespace
+
+const char ExitCodeWatcher::kParenthHandleSwitch[] = "parent-handle";
+
+ExitCodeWatcher::ExitCodeWatcher(const base::char16* registry_path) :
+    registry_path_(registry_path),
+    process_pid_(0) {
+}
+
+ExitCodeWatcher::~ExitCodeWatcher() {
+}
+
+bool ExitCodeWatcher::ParseArguments(const base::CommandLine& cmd_line) {
+  std::string process_handle_str =
+      cmd_line.GetSwitchValueASCII(kParenthHandleSwitch);
+  unsigned process_handle_uint = 0;
+  if (process_handle_str.empty() ||
+      !base::StringToUint(process_handle_str, &process_handle_uint)) {
+    LOG(ERROR) << "Missing or invalid parent-handle argument.";
+    return false;
+  }
+
+  HANDLE process_handle = reinterpret_cast<HANDLE>(process_handle_uint);
+  // Initial test of the handle, a zero PID indicates invalid handle, or not
+  // a process handle. In this case, bail immediately and avoid closing the
+  // handle.
+  DWORD process_pid = ::GetProcessId(process_handle);
+  if (process_pid == 0) {
+    LOG(ERROR) << "Invalid parent-handle, can't get parent PID.";
+    return false;
+  }
+
+  FILETIME creation_time = {};
+  FILETIME dummy = {};
+  if (!::GetProcessTimes(process_handle, &creation_time,
+                         &dummy, &dummy, &dummy)) {
+    LOG(ERROR) << "Invalid parent handle, can't get parent process times.";
+    return false;
+  }
+
+  // Success, take ownership of the process handle.
+  process_.Set(process_handle);
+  process_pid_ = process_pid;
+  process_creation_time_ = base::Time::FromFileTime(creation_time);
+
+  // Start by writing the value STILL_ACTIVE to registry, to allow detection
+  // of the case where the watcher itself is somehow terminated before it can
+  // write the process' actual exit code.
+  return WriteProcessExitCode(STILL_ACTIVE);
+}
+
+void ExitCodeWatcher::WaitForExit() {
+  int exit_code = 0;
+  if (!base::WaitForExitCode(process_.Get(), &exit_code)) {
+    LOG(ERROR) << "Failed to wait for process.";
+    return;
+  }
+  // WaitForExitCode closes the handle on success.
+  process_.Take();
+
+  WriteProcessExitCode(exit_code);
+}
+
+bool ExitCodeWatcher::WriteProcessExitCode(int exit_code) {
+  base::win::RegKey key(HKEY_CURRENT_USER,
+                        registry_path_.c_str(),
+                        KEY_WRITE);
+  base::string16 value_name(GetValueName(process_creation_time_, process_pid_));
+
+  ULONG result = key.WriteValue(value_name.c_str(), exit_code);
+  if (result != ERROR_SUCCESS) {
+    LOG(ERROR) << "Unable to write to registry, error " << result;
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace browser_watcher