Atmosphere/stratosphere/loader/source/ipc_templating.hpp

#pragma once
#include <switch.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <tuple>
#include <boost/callable_traits.hpp>
#include <type_traits>
#include <iomanip>

/* Represents an A descriptor. */
template <typename T>
struct InBuffer {
    T *buffer;
    size_t num_elements;
    BufferType type;
    
    InBuffer(void *b, size_t n) : buffer((T *)b), num_elements(n/sizeof(T)) { }
};

/* Represents a B descriptor. */
template <typename T>
struct OutBuffer {
    T *buffer;
    size_t num_elements;
    
    OutBuffer(void *b, size_t n) : buffer((T *)b), num_elements(n/sizeof(T)) { }
};

/* Represents an X descriptor. */
template <typename T>
struct InPointer {
    T *pointer;
    size_t num_elements;
    
    InPointer(void *p, size_t n) : pointer((T *)p), num_elements(n/sizeof(T)) { }
};

/* Represents a C descriptor. */
struct OutPointerWithServerSizeBase {};
 
template <typename T, size_t n>
struct OutPointerWithServerSize : OutPointerWithServerSizeBase {
    T *pointer;
    static const size_t num_elements = n;
    
    OutPointerWithServerSize(void *p) : pointer((T *)p) { }
};

/* Represents a C descriptor with size in raw data. */
template <typename T>
struct OutPointerWithClientSize {
    T *pointer;
    size_t num_elements;
    
    OutPointerWithClientSize(void *p, size_t n) : pointer((T *)p), num_elements(n/sizeof(T)) { }
};

/* Represents an input PID. */
struct PidDescriptor {
    u64 pid;
    
    PidDescriptor(u64 p) : pid(p) { }
};

/* Represents a moved handle. */
struct MovedHandle {
    Handle handle;
    
    MovedHandle(Handle h) : handle(h) { }
};

/* Represents a copied handle. */
struct CopiedHandle {
    Handle handle;
    
    CopiedHandle(Handle h) : handle(h) { }
};

/* Utilities. */
template <typename T, template <typename...> class Template>
struct is_specialization_of {
    static const bool value = false;
};

template <template <typename...> class Template, typename... Args>
struct is_specialization_of<Template<Args...>, Template> {
    static const bool value = true;
};

template<typename Tuple>
struct pop_front;

template<typename Head, typename... Tail>
struct pop_front<std::tuple<Head, Tail...>> {
    using type = std::tuple<Tail...>;
};

template <typename T>
struct is_ipc_buffer {
    static const bool value = is_specialization_of<T, InBuffer>::value 
                           || is_specialization_of<T, OutBuffer>::value 
                           || is_specialization_of<T, InPointer>::value 
                           || std::is_base_of<OutPointerWithServerSizeBase, T>::value 
                           || is_specialization_of<T, OutPointerWithClientSize>::value;
};

template <typename T>
struct size_in_raw_data {
    static const size_t value = (is_ipc_buffer<T>::value) ? 0 : ((sizeof(T) < sizeof(u32)) ? sizeof(u32) : (sizeof(T) + 3) & (~3));
};

template <typename ...Args>
struct size_in_raw_data_for_arguments {
    static const size_t value = (size_in_raw_data<Args>::value + ... + 0);
};

template <typename T>
struct size_in_raw_data_with_out_pointers {
    static const size_t value = is_specialization_of<T, OutPointerWithClientSize>::value ? 2 : size_in_raw_data<T>::value;
};

template <typename ...Args>
struct size_in_raw_data_with_out_pointers_for_arguments {
    static const size_t value = ((size_in_raw_data_with_out_pointers<Args>::value + ... + 0) + 3) & ~3;
};

template <typename T>
struct is_ipc_inbuffer {
    static const size_t value = (is_specialization_of<T, InBuffer>::value) ? 1 : 0;
};

template <typename ...Args>
struct num_inbuffers_in_arguments {
    static const size_t value = (is_ipc_inbuffer<Args>::value + ... + 0);
};

template <typename T>
struct is_ipc_inpointer {
    static const size_t value = (is_specialization_of<T, InPointer>::value) ? 1 : 0;
};

template <typename ...Args>
struct num_inpointers_in_arguments {
    static const size_t value = (is_ipc_inpointer<Args>::value + ... + 0);
};

template <typename T>
struct is_ipc_outpointer {
    static const size_t value = (is_specialization_of<T, OutPointerWithClientSize>::value || std::is_base_of<OutPointerWithServerSizeBase, T>::value) ? 1 : 0;
};

template <typename ...Args>
struct num_outpointers_in_arguments {
    static const size_t value = (is_ipc_outpointer<Args>::value + ... + 0);
};

template <typename T>
struct is_ipc_inoutbuffer {
    static const size_t value = (is_specialization_of<T, InBuffer>::value || is_specialization_of<T, OutBuffer>::value) ? 1 : 0;
};

template <typename ...Args>
struct num_inoutbuffers_in_arguments {
    static const size_t value = (is_ipc_inoutbuffer<Args>::value + ... + 0);
};


template <typename T>
struct is_ipc_handle {
    static const size_t value = (std::is_same<T, MovedHandle>::value || std::is_same<T, CopiedHandle>::value) ? 1 : 0;
};

template <typename ...Args>
struct num_handles_in_arguments {
    static const size_t value = (is_ipc_handle<Args>::value + ... + 0);
};

template <typename ...Args>
struct num_pids_in_arguments {
    static const size_t value = ((std::is_same<Args, PidDescriptor>::value ? 1 : 0) + ... + 0);
};

template<typename T>
T GetValueFromIpcParsedCommand(IpcParsedCommand& r, IpcCommand& out_c, u8 *pointer_buffer, size_t& pointer_buffer_offset, size_t& cur_rawdata_index, size_t& cur_c_size_offset, size_t& a_index, size_t& b_index, size_t& x_index, size_t& c_index, size_t& h_index) {
    const size_t old_rawdata_index = cur_rawdata_index;
    const size_t old_c_size_offset = cur_c_size_offset;
    const size_t old_pointer_buffer_offset = pointer_buffer_offset;
    if constexpr (is_specialization_of<T, InBuffer>::value) {
        return T(r.Buffers[a_index], r.BufferSizes[a_index++]);
    } else if constexpr (is_specialization_of<T, OutBuffer>::value) {
        return T(r.Buffers[b_index], r.BufferSizes[b_index++]);
    } else if constexpr (is_specialization_of<T, InPointer>::value) {
        return T(r.Statics[x_index], r.StaticSizes[x_index++]);
    } else if constexpr (std::is_base_of<OutPointerWithServerSizeBase, T>::value) {
        T t = T(pointer_buffer + old_pointer_buffer_offset);
        ipcAddSendStatic(&out_c, pointer_buffer + old_pointer_buffer_offset, t.num_elements * sizeof(*t.pointer), c_index++);
        return t;
    } else if constexpr (is_specialization_of<T, OutPointerWithClientSize>::value) {
        cur_c_size_offset += sizeof(u16);
        u16 sz = *((u16 *)((u8 *)(r.Raw) + old_c_size_offset));
        pointer_buffer_offset += sz;
        ipcAddSendStatic(&out_c, pointer_buffer + old_pointer_buffer_offset, sz, c_index++);
        return T(pointer_buffer + old_pointer_buffer_offset, sz);
    } else if constexpr (is_ipc_handle<T>::value) {
        return r.Handles[h_index++];
    } else if constexpr (std::is_same<T, PidDescriptor>::value) {
        return PidDescriptor(r.Pid);
    } else {
        cur_rawdata_index += size_in_raw_data<T>::value / sizeof(u32);
        return *((T *)((u32 *)r.Raw + old_rawdata_index));
    }
}

template <typename T>
bool ValidateIpcParsedCommandArgument(IpcParsedCommand& r, size_t& cur_rawdata_index, size_t& cur_c_size_offset, size_t& a_index, size_t& b_index, size_t& x_index, size_t& c_index, size_t& h_index, size_t& total_c_size) {
    const size_t old_c_size_offset = cur_c_size_offset;
    if constexpr (is_specialization_of<T, InBuffer>::value) {
        return r.Buffers[a_index] != NULL && r.BufferDirections[a_index++] == BufferDirection_Send;
    } else if constexpr (is_specialization_of<T, OutBuffer>::value) {
        return r.Buffers[b_index] != NULL && r.BufferDirections[b_index++] == BufferDirection_Recv;
    } else if constexpr (is_specialization_of<T, InPointer>::value) {
        return r.Statics[x_index] != NULL;
    } else if constexpr (std::is_base_of<OutPointerWithServerSizeBase, T>::value) {
        total_c_size += T::num_elements;
        return true;
    } else if constexpr (is_specialization_of<T, OutPointerWithClientSize>::value) {
        cur_c_size_offset += sizeof(u16);
        u16 sz = *((u16 *)((u8 *)(r.Raw) + old_c_size_offset));
        total_c_size += sz;
        return true;
    } else if constexpr (std::is_same<T, MovedHandle>::value) {
        return !r.WasHandleCopied[h_index++];
    } else if constexpr (std::is_same<T, CopiedHandle>::value) {
        return r.WasHandleCopied[h_index++];
    } else {
        return true;
    }
}

/* Validator. */
template <typename ArgsTuple>
struct Validator;

template<typename... Args>
struct Validator<std::tuple<Args...>> {
    IpcParsedCommand &r;
    size_t pointer_buffer_size;
    
	Result operator()() {
        if (r.RawSize < size_in_raw_data_with_out_pointers_for_arguments<Args... >::value) {
            return 0xF601;
        }
                        
        if (r.NumBuffers != num_inoutbuffers_in_arguments<Args... >::value) {
            return 0xF601;
        }
        
        if (r.NumStatics != num_inpointers_in_arguments<Args... >::value) {
            return 0xF601;
        }

        if (r.NumStaticsOut != num_outpointers_in_arguments<Args... >::value) {
            return 0xF601;
        }
        
        if (r.NumHandles != num_handles_in_arguments<Args... >::value) {
            return 0xF601;
        }
        
        constexpr size_t num_pids = num_pids_in_arguments<Args... >::value;
        
        static_assert(num_pids <= 1, "Number of PID descriptors in IpcCommandImpl cannot be > 1");
        
        if ((r.HasPid && num_pids == 0) || (!r.HasPid && num_pids)) {
            return 0xF601;
        }
        
        size_t a_index = 0, b_index = num_inbuffers_in_arguments<Args ...>::value, x_index = 0, c_index = 0, h_index = 0;
		size_t cur_rawdata_index = 4;
        size_t cur_c_size_offset = 0x10 + size_in_raw_data_for_arguments<Args... >::value + (0x10 - ((uintptr_t)r.Raw - (uintptr_t)r.RawWithoutPadding));
        size_t total_c_size = 0;
                
        if (!(ValidateIpcParsedCommandArgument<Args>(r, cur_rawdata_index, cur_c_size_offset, a_index, b_index, x_index, c_index, h_index, total_c_size) && ...)) {
            return 0xF601;
        }
        
        if (total_c_size > pointer_buffer_size) {
            return 0xF601;
        }

        return 0;
	}
};


/* Decoder. */
template<typename OutTuple, typename ArgsTuple>
struct Decoder;

template<typename OutTuple, typename... Args>
struct Decoder<OutTuple, std::tuple<Args...>> {
	static std::tuple<Args...> Decode(IpcParsedCommand& r, IpcCommand &out_c, u8 *pointer_buffer) {
        size_t a_index = 0, b_index = num_inbuffers_in_arguments<Args ...>::value, x_index = 0, c_index = 0, h_index = 0;
		size_t cur_rawdata_index = 4;
        size_t cur_c_size_offset = 0x10 + size_in_raw_data_for_arguments<Args... >::value + (0x10 - ((uintptr_t)r.Raw - (uintptr_t)r.RawWithoutPadding));
        size_t pointer_buffer_offset = 0;
		return std::tuple<Args... > {
				GetValueFromIpcParsedCommand<Args>(r, out_c, pointer_buffer, pointer_buffer_offset, cur_rawdata_index, cur_c_size_offset, a_index, b_index, x_index, c_index, h_index)
				...
		};
	}
};

/* Encoder. */
template<typename ArgsTuple>
struct Encoder;

template<typename T>
constexpr size_t GetAndUpdateOffsetIntoRawData(size_t& offset) {
	auto old = offset;
            
    if (old == 0) {
        offset += sizeof(u64);
    } else {
        offset += size_in_raw_data<T>::value;    
    }

	return old;
}

template<typename... Args>
struct Encoder<std::tuple<Args...>> {
    IpcCommand &out_command;
    
	auto operator()(Args... args) {
        static_assert(sizeof...(Args) > 0, "IpcCommandImpls must return std::tuple<Result, ...>");
		size_t offset = 0;
        
        u8 *tls = (u8 *)armGetTls();
        
        std::fill(tls, tls + 0x100, 0x100);
        
        /* Remove the extra space resulting from first Result type. */
        struct {
            u64 magic;
            u64 result;
        } *raw = (decltype(raw))ipcPrepareHeader(&out_command, sizeof(*raw) + size_in_raw_data_for_arguments<Args... >::value - sizeof(Result));
        
        raw->magic = SFCO_MAGIC;
        
        u8 *raw_data = (u8 *)&raw->result;
                
		((*((Args *)(raw_data + GetAndUpdateOffsetIntoRawData<Args>(offset))) = (args)), ...);
        
        if (R_FAILED(raw->result)) {
            ipcPrepareHeader(&out_command, sizeof(raw));
        }
                
        return raw->result;
	}
};


template<auto IpcCommandImpl, typename Class>
Result WrapIpcCommandImpl(Class *myfancypointer, IpcParsedCommand& r, IpcCommand &out_command, u8 *pointer_buffer, size_t pointer_buffer_size) {
    using InArgs = typename boost::callable_traits::args_t<decltype(IpcCommandImpl)>;
    using InArgsWithoutThis = typename pop_front<InArgs>::type;
    using OutArgs = typename boost::callable_traits::return_type_t<decltype(IpcCommandImpl)>;
    
    static_assert(is_specialization_of<OutArgs, std::tuple>::value, "IpcCommandImpls must return std::tuple<Result, ...>");
    static_assert(std::is_same_v<std::tuple_element_t<0, OutArgs>, Result>, "IpcCommandImpls must return std::tuple<Result, ...>");
    
    ipcInitialize(&out_command);

    Result rc = Validator<InArgsWithoutThis>{r, pointer_buffer_size}();
        
    if (R_FAILED(rc)) {
        return 0xF601;
    }

    auto args = Decoder<OutArgs, InArgsWithoutThis>::Decode(r, out_command, pointer_buffer);    
    auto result = std::apply( [=](auto&&... args) { return (myfancypointer->*IpcCommandImpl)(args...); }, args);
    
    return std::apply(Encoder<OutArgs>{out_command}, result);
}