Implement PermissionWizard checker

This adds a PermissionWizard::Delegate implementation which runs the
Me2Me or IT2Me binary with a command-line for checking permissions.

This can be used to create a PermissionWizard which checks the
permissions on either the ME2ME or IT2ME host.

Bug: 1015201
Change-Id: I24f24e5b1928608bbf310b33a6802db86c9f80bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903934Reviewed-by: Gary Kacmarcik <garykac@chromium.org>
Commit-Queue: Lambros Lambrou <lambroslambrou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714621}

remoting/host/mac/BUILD.gn

@@ -20,6 +20,23 @@ source_set("constants") {
   ]
 }
 
+source_set("permission_checking") {
+  sources = [
+    "permission_checker.cc",
+    "permission_checker.h",
+    "permission_process_utils.cc",
+    "permission_process_utils.h",
+    "permission_utils.h",
+    "permission_utils.mm",
+    "permission_wizard.h",
+    "permission_wizard.mm",
+  ]
+
+  deps = [
+    ":constants",
+  ]
+}
+
 executable("remoting_me2me_host_service") {
   sources = [
     "host_service_main.cc",
@@ -95,14 +112,8 @@ target("mac_app_bundle", "remoting_me2me_host") {
   #   defines = [ "REMOTING_ENABLE_BREAKPAD" ]
   # }
 
-  sources = [
-    "permission_utils.h",
-    "permission_utils.mm",
-    "permission_wizard.h",
-    "permission_wizard.mm",
-  ]
-
   deps = [
+    ":permission_checking",
     "//remoting/base:breakpad",
     "//remoting/host:main",
     "//remoting/host:remoting_me2me_host_static",

remoting/host/mac/permission_checker.cc

+// Copyright 2019 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 "remoting/host/mac/permission_checker.h"
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/task_runner_util.h"
+#include "remoting/host/mac/permission_process_utils.h"
+#include "remoting/host/version.h"
+
+namespace remoting {
+namespace mac {
+
+PermissionChecker::PermissionChecker(
+    HostMode mode,
+    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
+    : mode_(mode), io_task_runner_(io_task_runner) {}
+PermissionChecker::~PermissionChecker() = default;
+
+std::string PermissionChecker::GetBundleName() {
+  if (mode_ == HostMode::ME2ME) {
+    std::string host_bundle(HOST_BUNDLE_NAME);
+
+    // Strip off the ".app" suffix.
+    auto dot_position = host_bundle.rfind('.');
+    if (dot_position != std::string::npos) {
+      host_bundle = host_bundle.substr(0, dot_position);
+    }
+    return host_bundle;
+  }
+  return "remote_assistance_host";
+}
+
+void PermissionChecker::CheckAccessibilityPermission(
+    PermissionWizard::ResultCallback onResult) {
+  base::PostTaskAndReplyWithResult(
+      io_task_runner_.get(), FROM_HERE,
+      base::BindOnce(remoting::mac::CheckAccessibilityPermission, mode_),
+      std::move(onResult));
+}
+
+void PermissionChecker::CheckScreenRecordingPermission(
+    PermissionWizard::ResultCallback onResult) {
+  base::PostTaskAndReplyWithResult(
+      io_task_runner_.get(), FROM_HERE,
+      base::BindOnce(remoting::mac::CheckScreenRecordingPermission, mode_),
+      std::move(onResult));
+}
+
+}  // namespace mac
+}  // namespace remoting

remoting/host/mac/permission_checker.h

+// Copyright 2019 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.
+
+#ifndef REMOTING_HOST_MAC_PERMISSION_CHECKER_H_
+#define REMOTING_HOST_MAC_PERMISSION_CHECKER_H_
+
+#include "remoting/host/mac/permission_wizard.h"
+
+#include "base/single_thread_task_runner.h"
+#include "remoting/host/mac/permission_process_utils.h"
+
+namespace remoting {
+namespace mac {
+
+class PermissionChecker : public PermissionWizard::Delegate {
+ public:
+  PermissionChecker(HostMode mode,
+                    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);
+  PermissionChecker(const PermissionChecker&) = delete;
+  PermissionChecker& operator=(const PermissionChecker&) = delete;
+  ~PermissionChecker() override;
+
+  std::string GetBundleName() override;
+  void CheckAccessibilityPermission(
+      PermissionWizard::ResultCallback onResult) override;
+  void CheckScreenRecordingPermission(
+      PermissionWizard::ResultCallback onResult) override;
+
+ private:
+  HostMode mode_;
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+};
+
+}  // namespace mac
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_MAC_PERMISSION_CHECKER_H_

remoting/host/mac/permission_process_utils.cc

+// Copyright 2019 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 "remoting/host/mac/permission_process_utils.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "base/process/launch.h"
+#include "base/process/process.h"
+#include "remoting/host/mac/constants_mac.h"
+
+namespace remoting {
+namespace mac {
+
+namespace {
+
+base::FilePath GetHostExePath(HostMode mode) {
+  // Path to the host bundle top directory.
+  base::FilePath host_path(kHostBinaryPath);
+
+  host_path = host_path.Append("Contents/MacOS");
+  if (mode == HostMode::ME2ME)
+    return host_path.Append("remoting_me2me_host");
+
+  return host_path.Append(
+      "RemoteAssistanceHost.app/Contents/MacOS/remote_assistance_host");
+}
+
+bool CheckHostPermission(base::FilePath exe_path, std::string command_switch) {
+  base::CommandLine cmdLine(exe_path);
+  cmdLine.AppendSwitch(command_switch);
+
+  base::LaunchOptions options;
+  options.disclaim_responsibility = true;
+  base::Process process = base::LaunchProcess(cmdLine, options);
+  if (!process.IsValid()) {
+    LOG(ERROR) << "Unable to launch host process";
+    return false;
+  }
+  int exit_code;
+  process.WaitForExit(&exit_code);
+  LOG(INFO) << "Permission '" << command_switch << "' is "
+            << ((exit_code == 0) ? "granted" : "denied");
+  return exit_code == 0;
+}
+
+}  // namespace
+
+bool CheckAccessibilityPermission(HostMode mode) {
+  return CheckHostPermission(GetHostExePath(mode),
+                             "check-accessibility-permission");
+}
+
+bool CheckScreenRecordingPermission(HostMode mode) {
+  return CheckHostPermission(GetHostExePath(mode),
+                             "check-screen-recording-permission");
+}
+
+}  // namespace mac
+}  // namespace remoting

remoting/host/mac/permission_process_utils.h

+// Copyright 2019 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.
+
+#ifndef REMOTING_HOST_MAC_PERMISSION_PROCESS_UTILS_H_
+#define REMOTING_HOST_MAC_PERMISSION_PROCESS_UTILS_H_
+
+// Utilities for doing permission-checks in a separate process from the
+// ME2ME or IT2ME host binaries. These checks are carried out by running the
+// relevant binary (the one that needs the permission) with a command-line
+// option, and examining the returned exit-code.
+
+namespace remoting {
+namespace mac {
+
+enum class HostMode { ME2ME, IT2ME };
+
+// These methods must be called on a thread which allows blocking I/O.
+bool CheckAccessibilityPermission(HostMode mode);
+bool CheckScreenRecordingPermission(HostMode mode);
+
+}  // namespace mac
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_MAC_PERMISSION_PROCESS_UTILS_H_