1    :  // Copyright 2012 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  //
  15    :  // Helper functions to wrap RPC invocations.
  16    :  
  17    :  #ifndef SYZYGY_COMMON_RPC_HELPERS_H_
  18    :  #define SYZYGY_COMMON_RPC_HELPERS_H_
  19    :  
  20    :  #include <rpc.h>
  21    :  #include <wtypes.h>
  22    :  
  23    :  #include "base/macros.h"
  24    :  #include "base/process/process_handle.h"
  25    :  #include "base/strings/string_piece.h"
  26    :  
  27    :  // TODO(rogerm): Is there directly usable stuff in base/callback.h that
  28    :  //     might make this simpler/cleaner?
  29    :  
  30    :  namespace common {
  31    :  namespace rpc {
  32    :  
  33    :  // Create an RPC binding.
  34    :  //
  35    :  // @param protocol The RPC protocol to bind.
  36    :  // @param endpoint The endpoint/address to bind.
  37    :  // @param out_handle A handle to the rpc binding will be returned here.
  38    :  //
  39    :  // @returns true on success.
  40    :  bool CreateRpcBinding(const base::StringPiece16& protocol,
  41    :                        const base::StringPiece16& endpoint,
  42    :                        handle_t* out_handle);
  43    :  
  44    :  // Retrieves the PID for the RPC client process.
  45    :  //
  46    :  // @param binding An RPC binding.
  47    :  // @returns The client PID on success, or 0.
  48    :  base::ProcessId GetClientProcessID(handle_t binding);
  49    :  
  50    :  // Generic RPC call return structure. The ReturnType must be able to be
  51    :  // initialized with a zero.
  52    :  template<typename ReturnType>
  53    :  struct RpcResult {
  54  E :    RpcResult() : exception_occurred(FALSE), result(0) {}
  55    :  
  56    :    boolean exception_occurred;
  57    :    ReturnType result;
  58    :  
  59  E :    bool succeeded() const {
  60  E :      return exception_occurred == FALSE;
  61  E :    }
  62    :  };
  63    :  
  64    :  // Specialization of RpcResult used by most RPC calls.
  65    :  template<>
  66    :  struct RpcResult<boolean> {
  67  E :    RpcResult() : exception_occurred(FALSE), result(FALSE) {}
  68    :  
  69    :    boolean exception_occurred;
  70    :    boolean result;
  71    :  
  72  E :    bool succeeded() const {
  73  E :      return exception_occurred == FALSE && result == TRUE;
  74  E :    }
  75    :  };
  76    :  using RpcStatus = RpcResult<boolean>;
  77    :  
  78    :  // Helper to invoke an RPC function. Handles any number of paramters and auto
  79    :  // infers the return type based on the function signature.
  80    :  template<typename Func, typename ...Params>
  81    :  RpcResult<decltype(std::declval<Func>()(std::declval<Params>()...))>
  82  i :  InvokeRpc(const Func& func, Params... params) {
  83    :    using ReturnType = decltype(std::declval<Func>()(std::declval<Params>()...));
  84  i :    RpcResult<ReturnType> status;
  85  i :    RpcTryExcept {
  86  i :      status.result = func(params...);
  87  i :    } RpcExcept(1) {
  88  i :      status.exception_occurred = TRUE;
  89    :    } RpcEndExcept;
  90  i :    return status;
  91  i :  }
  92    :  
  93    :  // A helper function to get an @p instance_id specialized version of the
  94    :  // given @p root string.
  95    :  std::wstring GetInstanceString(const base::StringPiece16& root,
  96    :                                 const base::StringPiece16& instance_id);
  97    :  
  98    :  // A helper class to manage an RPC binding handle.
  99    :  class ScopedRpcBinding {
 100    :   public:
 101    :    ScopedRpcBinding();
 102    :    ~ScopedRpcBinding();
 103    :  
 104    :    // @returns the underlying RPC handle.
 105  E :    handle_t Get() const { return rpc_binding_; }
 106    :  
 107    :    // Opens an RPC connection to @p endpoint using @p protocol.
 108    :    bool Open(const base::StringPiece16& protocol,
 109    :              const base::StringPiece16& endpoint);
 110    :  
 111    :    // Closes this RPC connection.
 112    :    bool Close();
 113    :  
 114    :   protected:
 115    :    // The OS level binding to the RPC layer.
 116    :    handle_t rpc_binding_;
 117    :  
 118    :   private:
 119    :    DISALLOW_COPY_AND_ASSIGN(ScopedRpcBinding);
 120    :  };
 121    :  
 122    :  // A helper to manage an RPC interface registration.
 123    :  class ScopedRpcInterfaceRegistration {
 124    :   public:
 125    :    explicit ScopedRpcInterfaceRegistration(RPC_IF_HANDLE if_spec);
 126    :    ~ScopedRpcInterfaceRegistration();
 127    :  
 128    :    RPC_STATUS status() { return status_; }
 129    :  
 130    :   private:
 131    :    RPC_IF_HANDLE if_spec_;
 132    :    RPC_STATUS status_;
 133    :  };
 134    :  
 135    :  namespace internal {
 136    :  
 137    :  template <class T>
 138    :  struct dereference_pointer;
 139    :  
 140    :  template <class T>
 141    :  struct dereference_pointer<T*> {
 142    :    typedef T value;
 143    :  };
 144    :  
 145    :  }  // namespace internal
 146    :  
 147    :  template <class T>
 148  E :  RPC_WSTR AsRpcWstr(T* value) {
 149    :    static_assert(
 150    :        sizeof(internal::dereference_pointer<RPC_WSTR>::value) == sizeof(T),
 151    :        "Type is incompatible.");
 152  E :    return reinterpret_cast<RPC_WSTR>(value);
 153  E :  }
 154    :  
 155    :  }  // namespace rpc
 156    :  }  // namespace common
 157    :  
 158    :  #endif  // SYZYGY_COMMON_RPC_HELPERS_H_