Add resource message call and reply infrastructure.

ppapi/proxy/resource_message_params.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 PPAPI_PROXY_RESOURCE_MESSAGE_PARAMS_H_
+#define PPAPI_PROXY_RESOURCE_MESSAGE_PARAMS_H_
+
+#include "ipc/ipc_message_utils.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
+
+namespace ppapi {
+namespace proxy {
+
+// Common parameters for call and reply params.

[bbudge, 2012/06/18 17:23:47]

// Common parameters for resource call and reply messages ?

+class PPAPI_PROXY_EXPORT ResourceMessageParams {
+ public:
+  virtual ~ResourceMessageParams();
+
+  PP_Resource pp_resource() const { return pp_resource_; }
+  int32_t sequence() const { return sequence_; }
+
+ protected:
+  ResourceMessageParams();
+  ResourceMessageParams(PP_Resource resource, int32_t sequence);
+
+  virtual void Serialize(IPC::Message* msg) const;
+  virtual bool Deserialize(const IPC::Message* msg, PickleIterator* iter);
+
+ private:
+  PP_Resource pp_resource_;
+
+  // Identifier for this message. Sequence numbers are quasi-unique within a
+  // resource, but will overlap between different resource objects.
+  //
+  // If you send a lot of messages, the ID may wrap around. This is OK. All IDs
+  // are valid and 0 and -1 aren't special, so those cases won't confuse us.
+  // In practice, if you send more than 4 billion messages for a resource, the
+  // old ones will be long gone and there will be no collisions.
+  //
+  // If there is a malicious plugin (or exceptionally bad luck) that causes a
+  // wraparound and collision the worst that will happen is that we can get
+  // confused between different callbacks. But since these can only cause
+  // confusion within the plugin and within callbacks on the same resoruce,

[bbudge, 2012/06/18 17:23:47]

sp. resource

+  // there shouldn't be a security problem.
+  int32_t sequence_;
+};
+
+// Parameters common to all ResourceMessage "Call" requests.
+class PPAPI_PROXY_EXPORT ResourceMessageCallParams
+    : public ResourceMessageParams {
+ public:
+  ResourceMessageCallParams();
+  ResourceMessageCallParams(PP_Resource resource, int32_t sequence);
+  virtual ~ResourceMessageCallParams();
+
+  void set_has_callback() { flags_ |= kFlagHasCallback; }
+  bool has_callback() const { return flags_ & kFlagHasCallback; }
+
+  virtual void Serialize(IPC::Message* msg) const OVERRIDE;
+  virtual bool Deserialize(const IPC::Message* msg,
+                           PickleIterator* iter) OVERRIDE;
+
+ private:
+  uint32 flags_;
+
+  // Values used in the |flags| bitfield of ResourceRequest message.
+  static const unsigned kFlagHasCallback = 1 << 0;

[bbudge, 2012/06/18 17:23:47]

I'm wondering why this isn't just a bool. Will there be more flags? Since this
is private, it won't be possible for derived classes to define their own flags.

+};
+
+// Parameters common to all ResourceMessage "Reply" requests.
+class PPAPI_PROXY_EXPORT ResourceMessageReplyParams
+    : public ResourceMessageParams {
+ public:
+  ResourceMessageReplyParams();
+  ResourceMessageReplyParams(PP_Resource resource, int32_t sequence);
+  virtual ~ResourceMessageReplyParams();
+
+  void set_result(int32_t r) { result_ = r; }
+  int32_t result() const { return result_; }
+
+  virtual void Serialize(IPC::Message* msg) const OVERRIDE;
+  virtual bool Deserialize(const IPC::Message* msg,
+                           PickleIterator* iter) OVERRIDE;
+
+ private:
+  // Pepper "result code" for the callback.
+  int32_t result_;
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+namespace IPC {
+

[bbudge, 2012/06/18 17:23:47]

Is it typical for components that use IPC to put their param types into the IPC
namespace?

[brettw, 2012/06/18 17:33:53]

This is a template specialization so it has to be in the same namespace as the
original template.

+template <> struct PPAPI_PROXY_EXPORT
+ParamTraits<ppapi::proxy::ResourceMessageCallParams> {
+  typedef ppapi::proxy::ResourceMessageCallParams param_type;
+  static void Write(Message* m, const param_type& p) {
+    p.Serialize(m);
+  }
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
+    return r->Deserialize(m, iter);
+  }
+  static void Log(const param_type& p, std::string* l) {
+  }
+};
+
+template <> struct PPAPI_PROXY_EXPORT
+ParamTraits<ppapi::proxy::ResourceMessageReplyParams> {
+  typedef ppapi::proxy::ResourceMessageReplyParams param_type;
+  static void Write(Message* m, const param_type& p) {
+    p.Serialize(m);
+  }
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
+    return r->Deserialize(m, iter);
+  }
+  static void Log(const param_type& p, std::string* l) {
+  }
+};
+
+}  // namespace IPC
+
+#endif  // PPAPI_PROXY_RESOURCE_MESSAGE_PARAMS_H_