1    :  // Copyright 2015 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    :  // Declares RawArgumentConverter, a utility class for wrapping up generic
  16    :  // function arguments of different sizes and retrieving them in the necessary
  17    :  // types.
  18    :  #ifndef SYZYGY_BARD_RAW_ARGUMENT_CONVERTER_H_
  19    :  #define SYZYGY_BARD_RAW_ARGUMENT_CONVERTER_H_
  20    :  
  21    :  #include <stdint.h>
  22    :  
  23    :  #include "base/logging.h"
  24    :  #include "base/memory/scoped_ptr.h"
  25    :  
  26    :  namespace bard {
  27    :  
  28    :  // A simple class for wrapping function arguments of different sizes and safely
  29    :  // retrieving them in the desired type.
  30    :  class RawArgumentConverter {
  31    :   public:
  32    :    // Initializes a new raw argument.
  33    :    // @param arg_data a pointer to the argument to be saved.
  34    :    // @param arg_size the size in bytes of the argument.
  35    :    RawArgumentConverter(const void* const arg_data, const uint32_t arg_size);
  36    :  
  37    :    // Explicitly allow copy and assign for use with STL containers.
  38    :    RawArgumentConverter(const RawArgumentConverter&) = default;
  39    :    RawArgumentConverter& operator=(const RawArgumentConverter&) = default;
  40    :  
  41    :    // Retrieve this argument in the desired type.
  42    :    // @tparam Type The type that this argument should to be retrieved as.
  43    :    // @param value The value to be populated.
  44    :    // @returns true on success, false otherwise.
  45    :    template <typename Type>
  46    :    bool RetrieveAs(Type* value) const;
  47    :  
  48    :   private:
  49    :    static const size_t kMaxArgSize = 8;
  50    :    uint8_t arg_[kMaxArgSize];
  51    :    uint32_t arg_size_;
  52    :  };
  53    :  
  54    :  template <typename Type>
  55  E :  bool RawArgumentConverter::RetrieveAs(Type* value) const {
  56  E :    DCHECK_NE(static_cast<Type*>(nullptr), value);
  57  E :    if (sizeof(Type) != arg_size_)
  58  E :      return false;
  59  E :    ::memcpy(value, arg_, arg_size_);
  60  E :    return true;
  61  E :  }
  62    :  
  63    :  }  // namespace bard
  64    :  
  65    :  #endif  // SYZYGY_BARD_RAW_ARGUMENT_CONVERTER_H_