ipmid: Compiler-generated unpacking and packing of messages

handler.hpp has the templated wrapping bits for ipmi command handler
callbacks implemented.

message.hpp has the serialization/deserialization of the ipmi data
stream into packed tuples for functions.
message/pack.hpp and message/unpack.hpp contain the actual serialization
and deserialization of types.

Change-Id: If997f8768c8488ab6ac022526a5ef9a1bce57fcb
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>

1 files changed, 210 insertions, 0 deletions

diff --git a/include/ipmid/utility.hpp b/include/ipmid/utility.hpp
new file mode 100644
index 0000000..3a36434
--- /dev/null
+++ b/include/ipmid/utility.hpp
@@ -0,0 +1,210 @@
+/**
+ * Copyright © 2018 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+#include <boost/asio/spawn.hpp>
+#include <boost/callable_traits.hpp>
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <vector>
+
+namespace ipmi
+{
+
+struct Context;
+
+namespace utility
+{
+
+/**
+ * @brief a utility template to extract the args after N from a tuple
+ *
+ * Given a tuple of type <T1, ...TN, TN+1, ...>, provide type = tuple<TN+1,...>
+ */
+template <std::size_t N, typename FirstArg, typename... Rest>
+struct StripFirstArgs;
+
+template <std::size_t N, typename FirstArg, typename... Rest>
+struct StripFirstArgs<N, std::tuple<FirstArg, Rest...>>
+    : StripFirstArgs<N - 1, std::tuple<Rest...>>
+{
+};
+
+template <typename FirstArg, typename... Rest>
+struct StripFirstArgs<0, std::tuple<FirstArg, Rest...>>
+{
+    using type = std::tuple<FirstArg, Rest...>;
+};
+template <std::size_t N>
+struct StripFirstArgs<N, std::tuple<>>
+{
+    using type = std::tuple<>;
+};
+
+/**
+ * @brief a utility template to extract the remaining args from a tuple
+ *
+ * Given a tuple of type <T1, T2,...>, provide type = tuple<T2,...>
+ */
+template <typename T>
+using StripFirstArg = StripFirstArgs<1, T>;
+
+/**
+ * @brief a utility template to find the number of non-special arguments
+ *
+ * Given a tuple, count the args after the first special args
+ */
+template <typename FirstArg, typename... Rest>
+struct NonIpmiArgsCount;
+
+template <>
+struct NonIpmiArgsCount<std::tuple<>>
+{
+    constexpr static std::size_t size()
+    {
+        return 0;
+    }
+};
+template <typename FirstArg, typename... OtherArgs>
+struct NonIpmiArgsCount<std::tuple<FirstArg, OtherArgs...>>
+{
+    constexpr static std::size_t size()
+    {
+        if constexpr (std::is_same<FirstArg, ipmi::Context>::value ||
+                      std::is_same<FirstArg, boost::asio::yield_context>::value)
+        {
+            return 1 + NonIpmiArgsCount<std::tuple<OtherArgs...>>::size();
+        }
+        else
+        {
+            return NonIpmiArgsCount<std::tuple<OtherArgs...>>::size();
+        }
+    }
+};
+
+/**
+ * @brief a utility template to find the type of the first arg
+ *
+ * Given a tuple, provide the type of the first element
+ */
+template <typename T>
+struct GetFirstArg
+{
+    using type = void;
+};
+
+template <typename FirstArg, typename... Rest>
+struct GetFirstArg<std::tuple<FirstArg, Rest...>>
+{
+    using type = FirstArg;
+};
+
+/**
+ * @brief a utility template to remove const and reference from types
+ *
+ * Given a tuple, provide the type of the first element
+ */
+template <typename... Args>
+struct DecayTuple;
+
+template <typename... Args>
+struct DecayTuple<std::tuple<Args...>>
+{
+    using type = std::tuple<typename std::decay<Args>::type...>;
+};
+
+/** @brief Convert T[N] to T* if is_same<Tbase,T>
+ *
+ *  @tparam Tbase - The base type expected.
+ *  @tparam T - The type to convert.
+ */
+template <typename Tbase, typename T>
+using ArrayToPtr_t = typename std::conditional_t<
+    std::is_array<T>::value,
+    std::conditional_t<std::is_same<Tbase, std::remove_extent_t<T>>::value,
+                       std::add_pointer_t<std::remove_extent_t<T>>, T>,
+    T>;
+
+/** @brief Downcast type submembers.
+ *
+ * This allows std::tuple and std::pair members to be downcast to their
+ * non-const, nonref versions of themselves to limit duplication in template
+ * specializations
+ *
+ *  1. Remove references.
+ *  2. Remove 'const' and 'volatile'.
+ *  3. Convert 'char[N]' to 'char*'.
+ */
+template <typename T>
+struct DowncastMembers
+{
+    using type = T;
+};
+template <typename... Args>
+struct DowncastMembers<std::pair<Args...>>
+{
+    using type = std::pair<utility::ArrayToPtr_t<
+        char, std::remove_cv_t<std::remove_reference_t<Args>>>...>;
+};
+
+template <typename... Args>
+struct DowncastMembers<std::tuple<Args...>>
+{
+    using type = std::tuple<utility::ArrayToPtr_t<
+        char, std::remove_cv_t<std::remove_reference_t<Args>>>...>;
+};
+
+template <typename T>
+using DowncastMembers_t = typename DowncastMembers<T>::type;
+
+/** @brief Convert some C++ types to others for 'TypeId' conversion purposes.
+ *
+ *  Similar C++ types have the same dbus type-id, so 'downcast' those to limit
+ *  duplication in TypeId template specializations.
+ *
+ *  1. Remove references.
+ *  2. Remove 'const' and 'volatile'.
+ *  3. Convert 'char[N]' to 'char*'.
+ */
+template <typename T>
+struct TypeIdDowncast
+{
+    using type = utility::ArrayToPtr_t<
+        char, DowncastMembers_t<std::remove_cv_t<std::remove_reference_t<T>>>>;
+};
+
+template <typename T>
+using TypeIdDowncast_t = typename TypeIdDowncast<T>::type;
+
+/** @brief Detect if a type is a tuple
+ *
+ */
+template <typename>
+struct is_tuple : std::false_type
+{
+};
+
+template <typename... T>
+struct is_tuple<std::tuple<T...>> : std::true_type
+{
+};
+
+} // namespace utility
+
+} // namespace ipmi