Convert chromeos::CryptohomeClient::TpmCanAttemptOwnership to asynchronous

chromeos/dbus/cryptohome_client.h

 // Copyright (c) 2012 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 CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_
 #define CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 12 matching lines @@
 // CryptohomeClient is used to communicate with the Cryptohome service.
 // All method should be called from the origin thread (UI thread) which
 // initializes the DBusThreadManager instance.
 class CHROMEOS_EXPORT CryptohomeClient {
  public:
   // A callback to handle AsyncCallStatus signals.
   typedef base::Callback<void(int async_id, bool return_status, int return_code)
                          > AsyncCallStatusHandler;
   // A callback to handle responses of AsyncXXX methods.
   typedef base::Callback<void(int async_id)> AsyncMethodCallback;
+  // A callback to handle responses of methods without result values.
+  typedef base::Callback<void(
+      DBusMethodCallStatus call_status)> VoidMethodCallback;

[stevenjb, 2012/07/26 17:19:52]

This and the two callbacks below seem generic enough to be defined with
DBusMethodCallStatus?

[hashimoto, 2012/07/27 04:37:18]

Sounds good, will do in a separate patch.

   // A callback to handle responses of methods returning a bool value.
   typedef base::Callback<void(DBusMethodCallStatus call_status,
                               bool result)> BoolMethodCallback;
   // A callback to handle responses of methods returning a string value.
   typedef base::Callback<void(DBusMethodCallStatus call_status,
                               const std::string& result)> StringMethodCallback;
   // A callback to handle responses of Pkcs11GetTpmTokenInfo method.
   typedef base::Callback<void(
       DBusMethodCallStatus call_status,
       const std::string& label,
@@ skipping 72 matching lines @@
   virtual void TpmGetPassword(const StringMethodCallback& callback) = 0;
 
   // Calls TpmIsOwned method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool TpmIsOwned(bool* owned) = 0;
 
   // Calls TpmIsBeingOwned method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool TpmIsBeingOwned(bool* owning) = 0;
 
-  // Calls TpmCanAttemptOwnership method and returns true when the call
-  // succeeds.  This method blocks until the call returns.
-  virtual bool TpmCanAttemptOwnership() = 0;
+  // Calls TpmCanAttemptOwnership method.
+  virtual void TpmCanAttemptOwnership(const VoidMethodCallback& callback) = 0;

[stevenjb, 2012/07/26 17:19:52]

I'm confused about what this method does. It looks like it should return whether
or not we can attempt ownership, but in that case shouldn't the callback pass a
bool? Or does it tell cryptohome that it is OK to attempt ownership, in which
case we should rename this to something like SetTpmCanAttemptOwnership.

[hashimoto, 2012/07/27 04:37:18]

Looks like your latter guess is correct.
(http://git.chromium.org/gitweb/?p=chromiumos/platform/cryptohome.git;a=blob;f...)
This method is named badly from the beginning, I think it should be renamed to
something like MyabeStartInitializeTpm().
Anyway, I'm using the name "TpmCanAttemptOwnership" because the Cryptohome
service is providing the method with this name.
If we are going to rename this method, we should also rename Cryptohome
service's method name too.

[stevenjb, 2012/07/30 22:24:38]

OK, I see. That is definitely badly named. Can you at least comment what it does
and/or include the link?

[hashimoto, 2012/07/31 02:27:34]

Added a comment.

 
   // Calls TpmClearStoredPassword method and returns true when the call
   // succeeds.  This method blocks until the call returns.
   virtual bool TpmClearStoredPassword() = 0;
 
   // Calls Pkcs11IsTpmTokenReady method.
   virtual void Pkcs11IsTpmTokenReady(const BoolMethodCallback& callback) = 0;
 
   // Calls Pkcs11GetTpmTokenInfo method.
   virtual void Pkcs11GetTpmTokenInfo(
@@ skipping 32 matching lines @@
   // Create() should be used instead.
   CryptohomeClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CryptohomeClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_